In recent years, terrorist attacks have been spreading worldwide and become a public hazard to human society. The suspicious object detection system is an effective way to prevent terrorist attacks in public places. However, traditional systems face two main challenges: First, they need to conduct security checks at the entrance one by one, which leads to crowding; second, they rely heavily on screeners’ ability to understand security images, which can easily lead to misjudgment. To address these issues, we propose an AI-based W-band suspicious object detection system for moving persons that can perform a two-stage walkthrough screening for suspicious objects in an open area to maintain high throughput. The 1st screening uses millimeter wave radar and cameras to automatically screen suspects who may have concealed suspicious objects in an open area. The 2nd screening involves security personnel using a hybrid imager with active and passive imaging capabilities to identify the specific suspicious objects carried by the suspect. Convolutional neural network (CNN) based artificial intelligence (AI) technology will be used to improve the accuracy and speed of suspicious object detection. We performed an experiment to validate the proposed system. The usability and safety of the system are demonstrated by recognition rate (aka accuracy rate) or both recall and precision rate. In addition, in the process of improving the suspicious object recognition rate by AI techniques, we use generative adversarial network to help build a suspicious object database and successfully validate the effectiveness of the method and the factors affecting the suspicious object recognition rate to optimize the system.

This paper presents radio propagation characteristics in a typical indoor space in a 300 GHz Sub-THz broadband channel. We clarified path loss and cross-polarization characteristics in multiple spaces using a linearly polarized horn antenna with 24.6 dBi (E-plane beamwidth 4.5°) and 8.7 dBi (E-plane beamwidth 35°) and a newly developed RHCP circularly polarized patch array antenna which has a gain of 3.4 dBi (E-plane beamwidth 10°) at 300 GHz. We also clarified the effect of shielding by the human body. Furthermore, a comprehensive analysis using ray tracing confirms the accurate agreement of the root mean square delay spread.

The fifth generation (5G) aims to connect massive amounts of devices with higher reliability, lower latency, and faster transmission speed, which are vital for implementing e-health systems. However, the current efforts on 5G e-health systems are still not enough to accomplish its full blueprint. In this article, we first discuss the related technologies from the physical layer, upper layer, and cross-layer perspectives on designing 5G e-health systems. We then elaborate two use cases according to our implementations (i.e., 5G e-health systems for remote health and 5G e-health systems for Covid-19 pandemic containment). We finally envision the future research trends and challenges of 5G e-health systems.

The emergence of Artificial Intelligence of Things (AIoT) has provided novel insights for many social computing applications such as group recommender systems. As the distances between people have been greatly shortened, there has been more general demand for the provision of personalized services aimed at groups instead of individuals. The existing methods for capturing group-level preference features from individuals have mostly been established via aggregation and face two challenges: secure data management workflows are absent, and implicit preference feedback is ignored. To tackle these current difficulties, this paper proposes secure AIoT for implicit group recommendations (SAIoT-GR). For the hardware module, a secure IoT structure is developed as the bottom support platform. For the software module, a collaborative Bayesian network model and noncooperative game are introduced as algorithms. This secure AIoT architecture is able to maximize the advantages of the two modules. In addition, a large number of experiments are carried out to evaluate the performance of SAIoT-GR in terms of efficiency and robustness.

Along with the rapid development of IoT technology, Low power wide area network (LPWAN) has become the primary technology for IoT access today due to its characteristics of low cost, low power consumption, long-distance, and mass connections. At the same time, the points transfer system, as a typical third-party payment application, is attracting more and more extensive attention from academia and industry. Therefore, the research and development of a points transfer system for LPWAN are of great practical importance. However, the current points transfer systems often face problems such as centralization, high requirements on node computing power, and low robustness, which are difficult to adapt to the development of IoT. To address these problems, we propose a lightweight ledger-based points transfer system for application-oriented LPWAN. The system enables the points transfer between tags in LPWAN, where both tags and nodes are limited. Furthermore, it can be utilized even in disaster situations. Experimental results show that our proposed system is intensely robust and has a lower processing time than Bitcoin-like systems to cope with LPWAN's requirement.

In this paper, we propose a novel two-dimensional (2D) non-stationary geometry-based stochastic model (GBSM) for wideband multiple-input multiple-output (MIMO) base station-to-vehicle (B2V) channels. The proposed model combines one-ring and multiple ellipses with time-variant parameters, which can capture the channel non-stationary characteristics more precisely. The corresponding stochastic simulation model is then developed with finite number of effective scatterers. In addition, the birth-death process is applied to determine the number of ellipses in the proposed model at different time instants. Afterwards, the time-variant parameters and time-variant space cross-correlation functions (CCFs) are derived and analyzed. The impact of different parameters on the space CCFs such as vehicle traffic density (VTD) is investigated. Numerical results illustrate that the simulation model has great agreement with the reference model at different time instants, which indicates the correctness of our derivations.

Artificial Intelligence (AI) based millimeter wave radiometric imaging has become popular in a wide range of public security check systems, such as concealed object detection and identification. However, the low radiometric temperature contrast between small objects and low sensitivity is restricted to some extent. In this paper, an advanced radiometric passive imaging simulation model is proposed to improve the radiometric temperature contrast. This model considers additional noise, such as blur, variation in sensors, noise sources and summation of the number of frames. We establish a comprehensive training dataset that considers the physical characteristics of concealed objects. It can effectively fill the lack of a large database to avoid deteriorating the identification accuracy of AI applications. Moreover, it is also a key solution for improving the robustness of AI based object identification by using a convolutional neural network (CNN). Finally, simulation results are presented and analyzed to validate the proposed comprehensive training dataset and simulation model. Consequently, the proposed simulation model can effectively improve the robustness and accuracy of AI-based concealed object identification.

In the 5th generation mobile communication system (5G), there is a strong demand for higher speed and higher capacity. The beamforming technique using phased-array antennas is effective for long-distance radio propagation and for reducing interference signals in the high SHF (super high frequency) band because the phase shift of the antenna array elements can be controlled to produce a narrow-band beam and to control the directivity. We have developed the 28 GHz array antenna for small cells and evaluated the beamforming characteristics using an RF analog phase shifter control scheme. In this paper, we verify the computer simulation and evaluation results of the beamforming characteristics of a newly developed 4x4 phased array antenna.

Artificial Intelligence (AI) based millimeter wave radiometric imaging has become popular in a wide range of public security check systems, such as concealed object detection and identification. However, the low radiometric temperature contrast between small objects and low sensitivity is restricted to some extent. In this paper, an advanced radiometric passive imaging simulation model is proposed to improve the radiometric temperature contrast. This model considers additional noise, such as blur, variation in sensors, noise sources and summation of the number of frames. We establish a comprehensive training dataset that considers the physical characteristics of concealed objects. It can effectively fill the lack of a large database to avoid deteriorating the identification accuracy of AI applications. Moreover, it is also a key solution for improving the robustness of AI based object identification by using a convolutional neural network (CNN). Finally, simulation results are presented and analyzed to validate the proposed comprehensive training dataset and simulation model. Consequently, the proposed simulation model can effectively improve the robustness and accuracy of AI-based concealed object identification.

In the literature, Information communication technology (ICT)-assisted health systems have been intensively discussed. However, it has seldom become a reality. This is mainly due to the current wireless technologies' limited transmission rate, few connected devices and high latency. On the contrary, the fifth generation (5G) wireless communications can connect more devices, provide faster transmission rates and a lower latency. In this article, we first introduce the 5G-enabled health systems and our specific implementation in the first affiliated hospital of Zhengzhou University (FAHZZU). Afterwards, the potential challenges and future research trends on demonstrating the 5G-enabled health systems are discussed.

The location estimation accuracy of range-free localization (RFL) is a crucial issue in Wireless Sensor Networks (WSNs). The accuracy has significant impact on localization dependent routing protocols and applications. The assumption that the sensor nodes are deployed in regular areas without any obstacles do not match the practical deployment scenarios, especially for scenarios like outdoor deployment of WSNs. In this paper, we propose a hybrid solution by combining a RFL method and range-based localization (RBL) method namely Received Signal Strength Indication (RSSI) to tackle the detoured path between sensors in anisotropic network and to combat the last hop distance calculation problem respectively. As a result, our hybrid approach significantly improves the localization accuracy in anisotropic network as compared to range free method only. We calculate the average hop distance (AHD) of detoured path by estimating the angle of the middle of the transmission path between every two anchor pairs one by one. The AHD is finally adjusted by estimating the RSSI based last hop distance measurement. Based on the simulation results, it is observed that our hybrid approach with few anchor nodes outperforms other RFL algorithms in anisotropic network and indicates an improvement in the localization accuracy.

With the explosive growth of Internet of Things (IoT) devices, the demand for network systems is increasing rapidly. In terms of bandwidth, security, management, and more, there are many bottlenecks in current network systems. To address the above issues, future network technology, such as information-centric networking, is proposed to provide a good solution for IoT applications. However, new communications technologies need to be implemented with new communications applications. The traditional client/server-based network applications will become one of the bottlenecks in information-centric networking (ICN). In this paper, the work of the Ministry of Internal Affairs and Communications project at Waseda University over the past three years is summarized, and a highly efficient content-oriented common IoT platform for emergency management scenarios is proposed.

In fifth-generation wireless communications, data transmission is challenging due to the occurrence of burst errors and packet losses that are caused by multipath fading in multipath transmissions. To acquire more efficient and reliable data transmissions and to mitigate the transmission medium degradation in the 5G networks, it is important to study the error patterns or burst the error sequences that can provide insights into the behavior of 5G wireless data transmissions. In this paper, a two-state Markov-based 5G error model is investigated and developed to model the statistical characteristics of the underlying error process in the 5G network. The underlying 5G error process was obtained from our 5G wireless simulation, which was implemented based on three different kinds of modulation methods, including QPSK, 16QAM, and 64QAM, and was employed using the LDPC and TURBO coding methods. By comparing the burst or gap error statistics of the reference error sequences from the 5G wireless simulations and those of the generated error sequences from the two-state Markov error model, we show that the error behaviors of the coded OFDM 5G simulations can be adequately modeled by using the two-state Markov error model. Our proposed two-state Markov-based wireless error model can help to provide a more thorough understanding of the error process in 5G wireless communications and to evaluate the error control strategies with less computational complexity and shorter simulation times.

Information-centric networking (ICN) is a new approach to networking contents rather than devices that hold the contents. It has recently attracted much attention of network research and standardization communities. National and multi-national funded research projects have progressed worldwide. International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) started ICN standardization activities in 2012. In parallel, the standards-oriented research cooperation is progressing in the Information-Centric Networking Research Group (ICNRG) of the Internet Research Task Force (IRTF). All these global efforts have been collectively advancing the novel network architecture of ICN. However, there are very few surveys and discussions on the detailed ICN standardization status. To update the reader with information about the ICN research and standardization related activities, this paper starts with the history of global activities on ICN from 2010, giving references to various projects. It then describes the recent progress in the standardization of ICN component technologies in ITU-T and various documents produced by ICNRG. Lastly, it discusses the future directions for progressing ICN.

This research proposes an intelligent classification framework for quality of service (QoS) performance improvement in information-centric networking (ICN). The proposal works towards keyword classification techniques to obtain the most valuable information via suitable content prefixes in ICN. In this study, we have achieved the intelligent function using Artificial Intelligence (AI) implementation. Particularly, to find the most suitable and promising intelligent approach for maintaining QoS matrices, we have evaluated various AI algorithms, including evolutionary algorithms (EA), swarm intelligence (SI), and machine learning (ML) by using the cost function to assess their classification performances. With the goal of enabling a complete ICN prefix classification solution, we also propose a hybrid implementation to optimize classification performances by integration of relevant AI algorithms. This hybrid mechanism searches for a final minimum structure to prevent the local optima from happening. By simulation, the evaluation results show that the proposal outperforms EA and ML in terms of network resource utilization and response delay for QoS performance optimization.

This research proposes a novel wireless information-centric networking (ICN) architecture, namely, Context-Aware Green ICN Model (CAGIM), which can adapt the power consumption of network nodes to optimized values according to the associated link utilization. The power adaption in ICN nodes is conducted through dynamically adjusting the link-rate corresponding to content popularity and traffic load to reduce wasteful energy consumption. Moreover, we propose a smart popularity-based caching strategy, called distinguished caching scheme (DCS), with the introduction of hot and cold-caching partitions of ICN node's cache storage for popular and non-popular content objects, respectively. DCS improves the content diversity of the cache storage by adjusting, for each content, the number of chunks to be cached at ICN nodes based on its type and popularity level. DCS thus can further decrease the network system power consumption, thanks to its improved cache hit that reduces network traffic load. Toward the goal of realizing a context-aware green wireless network system with efficient content delivery, we also design a Wi-Fi Direct based scheme as an alternative approach to minimize power consumption and latency by sharing essential/important content objects via direct communications with power-saving mechanisms in the case that wireless local area network connections are not available. The evaluation results show that CAGIM can improve network efficiency by reducing both hop-count and power consumption considerably compared with existing wireless network systems with different well-known caching schemes. This proposal enables a flexible and efficient content delivery mechanism for future networks with various real-life scenarios, like Green building, Green company, and Green campus content accesses.

In this article, the transmission performance of a circle polarization shift keying (CPolSK)-based free space optical (FSO) system working in space-to-ground channel is analyzed. Formulas describing the optical polarization distortion caused by the atmospheric turbulence and the communication qualities in terms of signal-to-noise-ratio (SNR), bit-error-ratio (BER) and outage probability of the proposed system are derived. Based on the Stokes parameters data measured by a Japanese optical communication satellite, we evaluate the space-to-ground FSO link and simulate the system performance under a varying regime of turbulence strength. The proposed system provides a more efficient way to compensate scintillation effects in a comparison with the on-off-keying (OOK)-based FSO system. These results are useful to the designing and evaluating of a deep space FSO communication system.

The Macro-Femtocell system is widely used in current society because the cooperation between Macrocell base stations and Femtocell base stations can improve the communication capacity of certain areas and adapt to the large multi-user demand. To increase the system's communication quality, the handover scheme should be utilized when the user is moving within the limited coverage of Femtocell base stations. Generally, the Markov decision strategy is used for mobile users in the process of handover. However, the Markov decision process can't ensure the maximum utilization balance of Macrocell base stations and Femtocell base stations. In this case, users often choose the base station offering the highest signal strength, which will cause a Macrocell base station's load to be too large and Femtocell base stations to be idle, so the system's utilization is very low. To address this problem, we propose the utilization efficient game-theoretical handover scheme based on Starckberg competition theory for appropriately increasing a Femtocell base station's transmitting power. This can ensure the communication quality of the system and guarantees the system's load balance to induce users to take the initiative in processing the handover scheme. Finally, the simulation results show that our strategy is effective in choosing the best base station to receive the highest signal strength by predicting the user's movement. It could also realize the load balance of the antenna in the system. The overall transmission quality of the user group is optimized.

The non-regenerative massive multi-input-multi-output (MIMO) non-orthogonal multiple access (NOMA) relay systems are introduced in this paper. The NOMA is invoked with a superposition coding technique at the transmitter and successive interference cancellation (SIC) technique at the receiver. In addition, a maximum mean square error-SIC receiver design is adopted. With the aid of deterministic equivalent and matrix analysis tools, a closed-form expression of the signal to interference plus noise ratio (SINR) is derived. To characterize the performance of the considered systems, closed-form expressions of the capacity and sum rate are further obtained based on the derived SINR expression. Insights from the derived analytical results demonstrate that the ratio between the transmitter antenna number and the relay number is a dominate factor of the system performance. Afterward, the correctness of the derived expressions are verified by the Monte Carlo simulations with numerical results. Simulation results also illustrate that: 1) the transmitter antenna, averaged power value, and user number display the positive correlations on the capacity and sum rate performances, whereas the relay number displays a negative correlation on the performance and 2) the combined massive-MIMO-NOMA scheme is capable of achieving higher capacity performance compared with the conventional MIMO-NOMA, relay-assisted NOMA, and massive-MIMO orthogonal multiple access (OMA) scheme.

Localization is an important aspect in the field of wireless sensor networks (WSNs) that has developed significant research interest among academia and research community. Wireless sensor network is formed by a large number of tiny, low energy, limited processing capability and low-cost sensors that communicate with each other in ad-hoc fashion. The task of determining physical coordinates of sensor nodes in WSNs is known as localization or positioning and is a key factor in today’s communication systems to estimate the place of origin of events. As the requirement of the positioning accuracy for different applications varies, different localization methods are used in different applications and there are several challenges in some special scenarios such as forest fire detection. In this paper, we survey different measurement techniques and strategies for range based and range free localization with an emphasis on the latter. Further, we discuss different localization-based applications, where the estimation of the location information is crucial. Finally, a comprehensive discussion of the challenges such as accuracy, cost, complexity, and scalability are given.

In order to support seamless mobility in the Information- Centric Networking (ICN) Architecture we propose the Named-Node Network Architecture (3NA). 3NA introduces two independent namespaces to ICN, the 3N namespace used to uniquely identify nodes within a network and the Point of Attachment (PoA) namespace to identify a node's PoA to the network. The mappings between the two namespaces, along with all the necessary mechanisms to keep the mappings updated over time, are used when routing ICN packets to improve delay and the goodput when either the producer or the consumer are mobile. To support simultaneous producer and consumer mobility, we expand on the 3NA by adding a new Protocol Data Unit (PDU), the DU PDU. The DU PDU permits the encapsulation of ICN packets in a header that has source and destination name fields which belong to 3NA's 3N namespace. The new PDU permits seamless connectivity as long as 3NA's point of attachment signaling is strictly followed. We demonstrate the performance of the DU PDU against our previous defined communication methods and Named Data Networking's (NDN) Smart Flooding forwarding strategy using our open source nnnSIM module for the ns-3 framework. The new PDU outperforms all existing alternatives when the producer or both consumer and provider are mobile, obtaining overall lower mean network delay and higher median goodput.

Non-orthogonal multiple access (NOMA), millimeter wave (mmWave), and massive multiple-input-multiple-output (MIMO) have been emerging as key technologies for fifth generation mobile communications. However, less studies have been done on combining the three technologies into the converged systems. In addition, how many capacity improvements can be achieved via this combination remains unclear. In this paper, we provide an in-depth capacity analysis for the integrated NOMA-mmWave-massive-MIMO systems. First, a simplified mmWave channel model is introduced by extending the uniform random single-path model with angle of arrival. Afterward, we divide the capacity analysis into the low signal to noise ratio (SNR) and high-SNR regimes based on the dominant factors of signal to interference plus noise ratio. In the noise-dominated low-SNR regime, the capacity analysis is derived by the deterministic equivalent method with the Stieltjes-Shannon transform. In contrast, the statistic and eigenvalue distribution tools are invoked for the capacity analysis in the interference-dominated high-SNR regime. The exact capacity expression and the low-complexity asymptotic capacity expression are derived based on the probability distribution function of the channel eigenvalue. Finally, simulation results validate the theoretical analysis and demonstrate that significant capacity improvements can be achieved by the integrated NOMA-mmWave-massive-MIMO systems.

In this paper, we introduce a key technology, polarization modulation (PM), which should be taken into account when standardizing outdoor optical wireless communications (OWC), also known as free-space optical communications (FSO). We analyze the distortion of the polarization state when a laser beam propagates through the atmospheric channel. The floating range of the optical polarization was estimated and the necessity of researching the proposed technology was discussed. Moreover, we conducted a comparison between the PM-based FSO system and intensity modulation-based FSO system. The conclusions will be helpful in establishing the FSO standard architectures.

We propose the node name routing (NNR) strategy for information-centric ad-hoc networks based on the named-node networking (3N). This strategy is especially valuable for use in disaster areas because, when the Internet is out of service during a disaster, our strategy can be used to set up a self-organizing network via cell phones or other terminal devices that have a sharing ability, and it does not rely on a base station (BS) or similar providers. Our proposed strategy can solve the multiple-name problem that has arisen in prior 3N proposals, as well as the dead loop problems in both 3N ad-hoc networks and TCP/IP ad-hoc networks. To evaluate the NNR strategy, it is compared with the optimized link state routing protocol (OLSR) and the dynamic source routing (DSR) strategy. Computer-based comprehensive simulations showed that our NNR proposal exhibits a better performance in this environment when all of the users are moving randomly. We further observed that with a growing number of users, our NNR protocol performs better in terms of packet delivery, routing cost, etc.

© 2017 The Institute of Electronics, Information and Communication Engineers. We propose the node name routing (NNR) strategy for information-centric ad-hoc networks based on the named-node networking (3N). This strategy is especially valuable for use in disaster areas because, when the Internet is out of service during a disaster, our strategy can be used to set up a self-organizing network via cell phones or other terminal devices that have a sharing ability, and it does not rely on a base station (BS) or similar providers. Our proposed strategy can solve the multiple-name problem that has arisen in prior 3N proposals, as well as the dead loop problems in both 3N ad-hoc networks and TCP/IP ad-hoc networks. To evaluate the NNR strategy, it is compared with the optimized link state routing protocol (OLSR) and the dynamic source routing (DSR) strategy. Computer-based comprehensive simulations showed that our NNR proposal exhibits a better performance in this environment when all of the users are moving randomly. We further observed that with a growing number of users, our NNR protocol performs better in terms of packet delivery, routing cost, etc.

<p>In order to support seamless mobility in the Information-Centric Networking (ICN) Architecture we propose the Named-Node Network Architecture (3NA). 3NA introduces two independent namespaces to ICN, the 3N namespace used to uniquely identify nodes within a network and the Point of Attachment (PoA) namespace to identify a node's PoA to the network. The mappings between the two namespaces, along with all the necessary mechanisms to keep the mappings updated over time, are used when routing ICN packets to improve delay and the goodput when either the producer or the consumer are mobile. To support simultaneous producer and consumer mobility, we expand on the 3NA by adding a new Protocol Data Unit (PDU), the DU PDU. The DU PDU permits the encapsulation of ICN packets in a header that has source and destination name fields which belong to 3NA's 3N namespace. The new PDU permits seamless connectivity as long as 3NA's point of attachment signaling is strictly followed. We demonstrate the performance of the DU PDU against our previous defined communication methods and Named Data Networking's (NDN) Smart Flooding forwarding strategy using our open source nnnSIM module for the ns-3 framework. The new PDU outperforms all existing alternatives when the producer or both consumer and provider are mobile, obtaining overall lower mean network delay and higher median goodput.</p>

<p>In order to support seamless mobility in the Information-Centric Networking (ICN) Architecture we propose the Named-Node Network Architecture (3NA). 3NA introduces two independent namespaces to ICN, the 3N namespace used to uniquely identify nodes within a network and the Point of Attachment (PoA) namespace to identify a node's PoA to the network. The mappings between the two namespaces, along with all the necessary mechanisms to keep the mappings updated over time, are used when routing ICN packets to improve delay and the goodput when either the producer or the consumer are mobile.</p><p> To support simultaneous producer and consumer mobility, we expand on the 3NA by adding a new Protocol Data Unit (PDU), the DU PDU. The DU PDU permits the encapsulation of ICN packets in a header that has source and destination name fields which belong to 3NA's 3N namespace. The new PDU permits seamless connectivity as long as 3NA's point of attachment signaling is strictly followed. We demonstrate the performance of the DU PDU against our previous defined communication methods and Named Data Networking's (NDN) Smart Flooding forwarding strategy using our open source nnnSIM module for the ns-3 framework. The new PDU outperforms all existing alternatives when the producer or both consumer and provider are mobile, obtaining overall lower mean network delay and higher median goodput.</p>

In order to address the energy issue and enhance the feasibility of Information-Centric Networking (ICN) in the case of access networks, this research proposes a novel Green ICN design which can adapt power consumption of network devices to their optimized real-time link-utilizations based on content popularity levels. We utilize dynamic ALR (Adaptive Link Rate) based scheme for content nodes to provide efficient content delivery as a realistic approach for the economically viable green network. We also develop a game-theoretical model to study the interaction between an ISP and a network equipment company in the context of green networking. Specifically, we present the system concept and some demonstration results of game-based Green ICN model to analyze the economic incentives of players. Moreover, we discuss ICN deployment and standardization challenges, then show that the proposal is robust, easy to deploy and practically relevant for the network players.

Besides the prior study of energy efficiency (EE) that focuses on single component (antenna, radio frequency (RF) chain, circuit, etc.), or limited to one base station (BS) area, in this paper, EE is integrated, investigated with various components (antenna, RF chain, circuit, coverage area) considering in, based on an optimized system model. That is, one optimized multi-BS system model is introduced beforehand with the cloud radio access network (C-RAN) for easier deployment of the selecting/sleeping mechanism. In addition, the system EE is described by an optimization problem while taking more component factors into consideration. While solving, this integrated optimization problem in all time intervals of all BS areas is proved to be equal to an optimization problem of each single BS area within each single time interval. After that, the integrated optimization solution is obtained while adding up the single-BS-single-interval optimization solutions, whereas the later solution is addressed by an offline decision method plus a convex optimization strategy. Observation from the numerical results demonstrates that the antenna power consumption is the dominant factor of the power consumption, which therefore, the dominant factor of EE performance.

Besides the prior study of energy efficiency (EE) that focuses on single component (antenna, radio frequency (RF) chain, circuit, etc.), or limited to one base station (BS) area, in this paper, EE is integrated, investigated with various components (antenna, RF chain, circuit, coverage area) considering in, based on an optimized system model. That is, one optimized multi-BS system model is introduced beforehand with the cloud radio access network (C-RAN) for easier deployment of the selecting/sleeping mechanism. In addition, the system EE is described by an optimization problem while taking more component factors into consideration. While solving, this integrated optimization problem in all time intervals of all BS areas is proved to be equal to an optimization problem of each single BS area within each single time interval. After that, the integrated optimization solution is obtained while adding up the single-BS-single-interval optimization solutions, whereas the later solution is addressed by an offline decision method plus a convex optimization strategy. Observation from the numerical results demonstrates that the antenna power consumption is the dominant factor of the power consumption, which therefore, the dominant factor of EE performance.

To further enhance the energy efficiency (EE) performance of fifth generation (5G) Internet of Things systems, an integrated structure is proposed in this paper. That is, other than prior studies that separately study the wireless and wired parts, the wireless and wired parts are holistically combined together to comprehensively optimize the EE of the whole system. The integrated system structure is introduced beforehand with the proposed unified control center components for better deployment of the select-and-sleep mechanism. In addition, in the wireless part, one cellular partition zooming (CPZ) mechanism is proposed. In contrast, in the wired part, a precaching mechanism is introduced. With these proposals, the proposed system EE performance is investigated. Comprehensive computer-based simulation results demonstrate that the proposed schemes display better EE performance. This is due to the fact that system power consumption is further reduced with these schemes as compared to the prior work.

In order to provide high-quality and highly reliable video delivery services for mobile users, especially train passengers, we propose a proactive content caching scheme that uses transportation systems. In our system, we place content servers with cache capability [e.g., content centric networking/named data networking (CCN/NDN)] in every train and station. Video segments encapsulated by MPEG-Dynamic Adaptive Streaming over HTTP (MPEG-DASH) are distributed and pre-cached by the station servers before the trains arrive at the stations. The trains receive content via high-speed wireless transport, such as wireless LANs or millimeter waves, when they stop at the stations. We developed prototype systems based on hypertext transfer protocol and CCN/NDN protocol, evaluate their performance through two field experiments that uses actual trains, and compare with traditional video streaming over cellular networks. Such evaluations indicate that our system can achieve high-quality video delivery without interruption for up to 50 users simultaneously.

Energy efficient object detection and image transmission are one of the key issues in wireless multimedia sensor networks (WMSN). Recent approaches in the WMSN propose in-node object detection and tracking algorithms. However, a little effort has been made to effectively detect object presence and absence in images in the WMSN. Since object detection has a direct relation with image transmission, therefore effective object detection algorithm would provide a reduction in the false transmission of image information. In this paper, a novel object presence model and an image transmission scheme are proposed for the WMSN. This scheme uses the transmission of image segments rather than a complete image. It guarantees in-node energy conservation and minimal image content transmission to the sink node. The proposed scheme is evaluated based on in-node energy consumption and reconstructed image peak signal-to-noise ratio (PSNR). Simulation results show that the proposed approach saves 95% of the node energy with the received image PSNR of 46 dB as compared with other state-of-the- art approaches.

In this paper, we propose to implement a consecutive polarization modulation (CPolM) scheme to transmit orthogonal frequency division multiplexing (OFDM) signal over the turbulent free-space optical (FSO) links. We analyze the fluctuation of polarization states of an optical wave while propagating through the turbulence channel of which the refractive-index property is described by Kolmogorov spectrum. The transmission performance in terms of signal-to-noise-ratio (SNR), symbol-error-ratio (SER) and outage probability of the proposed system are evaluated. The proposed system provides a more efficient way to compensate scintillation effects in a comparison with the intensity modulation (IM) based OFDM FSO system under a varying degrees of turbulence strength regimes. (C) 2016 Elsevier B.V. All rights reserved.

The information revolution process is boosting the development of social big data. Other than the use of traditional sampling of statistical methods to analysis data, people nowadays shifts to use the real-time data. And the transmission of massive data puts forward new demands. Here in this paper, to cater this trend, with the proposed new way of packets transmission management with Information-Centric Network (ICN), the transmission is compared with traditional IP based transmission, which simulation results demonstrated that both the network transmission speed and efficiency improved significantly by our method.

In this article, we construct a concrete model as the prototype of efficient and reliable wireless Information Centric Networking (ICN) within the context of Intelligent Transport System (ITS). This research proposes a novel proactive-caching technique in ICN providing the robust and effective content delivery to the mobile nodes (commuters) for transportation system and fitting numerous ICN mobility scenarios of transportation system thanks to our "smart scheduler". We also propose a wireless ICN architecture which can adapt the power consumption of network nodes to the actual values of their optimized utilizations for greening the transportation communication network. Moreover, we identify that there are currently various ICN-based models and emphasize the need of an official international standard for wireless communication in general and transportation system in particular. Then by evaluating our proposal, we show that our proposal is a promising and feasible contribution for the ITU standardization process of Data Aware Networking (DAN) by integrating Green networking into DAN to combine the benefits of innovated rate-adaptivity and proactive-caching based schemes for achieving highly scalable, reliable and energy-efficient network performance in future transportation Information-centric communication system with data-awareness.

Home network (HOMENET) performs multiple important functions such as energy management, multimedia sharing, lighting and climate control in smart grid (SG). In HOMENET there are numerous challenges among which mobility and security are the basic requirements that need to be addressed with priority. The information-centric networking (ICN) is regarded as the future Internet that subscribes data in a content-centric manner irrespective of its location. Furthermore, it has pecial merit in mobility and security since ICN supports in-network caching and self-contained security, these make ICN a potential solution for home communication fabric. This paper aims to apply the ICN approach on HOMENET system, which we called ICN-HOMENET. Then, a proof-of-concept evaluation is employed to evaluate the effectiveness of the proposed ICN-HOMENET approach in data security, device mobility and efficient content distribution for developing HOMENET system in SG. In addition, we proposed a cost-efficient residential energy management (REM) scheme called ICN-REM scheme for ICN-HOMENET system which encourages consumers to shift the start time of appliances from peak hours to off-peak hours to reduce the energy bills. To the best of our knowledge, this is the first attempt to propose an ICN-based REM scheme for HOMENET system. In this proposal, we not only consider the conflicting requests from appliances and domestic power generation, but also think the energy management unit (EMU) should cooperate with measurement sensors to control some specific appliances in some specific conditions. Moreover, the corresponding performance evaluation validates its correctness and effectiveness.

Recently, miniaturization, low cost and standardization activates of the wireless sensor network technologies has been remarkably advanced, because of advancement of the wireless technologies. Especially smart grid is important application of the wireless sensor network technologies. In the smart grid network, the network congestion occurs caused by huge traffic in real time transmission of energy usage data or environment information data in the house or building. It is required to effectively collect the data and improve the network efficiency. We describes the scheme and the results in this paper since we clarified the efficient data transmission based on data fusion method for the energy usage data using Back Propagation (BP) algorithm with Artificial Neural Network.

A Pseudo Double Scattering Channel (PDSC) Matrix assumption is proposed here for downlink Non-Orthogonal Multiple Access (NOMA) within massive Multi-Input Multi-Output (MIMO) systems. Afterwards, outage probability analysis of such a system is investigated. That is, with the aid of random matrix and statistics theories, the Cumulative Probability Distribution (CDF) and also the outage probability performance are addressed. After that, the mathematics derivations obtained here are verified through numerical simulation results, wherein we further find out that with antenna number increasing, the system outage probability performance is reduced.

Based on the Cloud-Radio Access Network (C-RAN) structure and massive Multi-Input Multi-Output (MIMO), we propose one comprehensive system model and give the Energy Efficiency (EE) analysis of this system. The C-RAN structure is amended for better antenna control in massive MIMO based C-RAN system model. Furthermore, system EE optimization problem is modeled from a comprehensive way, and its solution is addressed with a convex optimization method plus an offline decision. In EE analysis, apart from the prior literature, Carrier Capacity (CC), antenna, Radio-Frequency (RF) chain, machine room and also the electron circuits are integrally taken into consideration. A positive correlation is observed between CC and the EE performance prior to the optimal value, after this optimal value, further increase CC has little help to EE enhancement.

Urban surveillance systems are being applied in a rapid pace with mature but inefficient solutions. The inefficiency is revealed with two aspects, too concentrated bandwidth and processing requirement. To solve this problem, we proposed a content oriented surveillance system based on Information-Centric Network. However, we can't simply replace TCP/IP streaming structure with named contents streaming structure because it can't improve the surveillance system's efficiency enough. In this paper, we took the ICN network's profits even further with the named contents. Instead of streaming live video to the central data center and processing multiple data stream in the same time, we have designed the nodes to process the captured raw data and produce objective contents for the central data center. With the extremely size difference in raw data and actual valued contents from it, we could apply the method in investigating area people traffic conditions and even in disaster and anti-terrorism scenarios. There was a field experiment performed to evaluate tourists' densities and dressing habits during winter season of March. The experiment expressed the benefits of our system and compared our method with traditional surveillance systems in saving network bandwidth and functionalities.

This paper presents a novel model of heterodyne-detected optical code-division multiple-access (OCDMA) systems employing polarization shift keying (PolSK) modulation over a free-space optical (FSO) turbulence channel. In this article, a new transceiver configuration and detailed analytical model for the proposed system are provided and discussed, taking into consideration the potential of heterodyne detection on mitigating the impact of turbulence-induced irradiance fluctuation on the performance of the proposed system under the gamma-gamma turbulence channel. Furthermore, we derived the closed-form expressions for the system error probability and outage probability, respectively. We determine the advantages of the proposed modeling by performing a comparison with a direct detection scheme obtained from an evaluation of link performance under the same environment conditions. The presented work also shows the most significant impact factor that degrades the performance of the proposed system and indicates that the proposed approach offers an optimum link performance compared to conventional cases.

© 2015 American Physical Society.We studied the physical properties of hollandite titanates, BaxTi8O16+δ, which have double chains of edge-sharing TiO6 octahedra with d electrons in the t2g states. We found that there is an electronic phase transition at ∼220 K, at which various properties exhibit anomalies. This phase transition is characterized by a modulation in the TiO6 chains and a spectral weight transfer of over 2 eV in the optical conductivity spectrum, which are presumably caused by charge and orbital ordering of the Ti t2g electrons.

Advanced metering infrastructure (AMI), as the totality of systems and networks to measure, collect, store, analyze, and use energy usage data, is supposed to be the core component in smart grid. In AMI, there are numerous challenges among which cyber security is a major one that needs to be addressed with priority. The information centric networking (ICN) is a promising architecture for the future Internet that disseminates content based on named data instead of named hosts. The congestion control and self-security can enable more scalable, secure, collaborative, and pervasive networking, these make the ICN a potential network architecture for smart grid. This paper aims to apply the ICN approach on AMI system, which we termed as information centric AMI (ICN-AMI). To the best of our knowledge, this is the first attempt to distribute contents (or requests for contents) based on ICN in AMI system. Moreover, a simulation-based performance evaluation is employed to evaluate the effectiveness of the proposed ICN-AMI approach in traffic control for developing AMI system in smart grid. In addition, we proposed a novel key management scheme (KMS) for a large number of smart meters in this system to ensure confidentiality, integrality, and authentication. To validate the scheme, the security analysis, comparisons are done to demonstrate that the proposed information centric KMS (ICN-KMS) is possible and a promising solution for ICN-AMI system.

Information Centric Networking (ICN) had merits in terms of mobility, security, power consumption and network traffic. When a large-scale disaster occurred, the current communication system might be fragile and the server based network service might be unavailable due to the damages, network congestions, and power failure, etc. In this paper, we proposed an ICN based Disaster Information Sharing Service (DISS) [1], [2] system. DISS could provide robust information sharing service. Users could publish disaster information as a content message with the help of our DISS. In addition, by utilizing DISS's message naming strategy, users could retrieve disaster information even without a server connection. The ICN based DISS could reduce the probability of network congestion when a large number of simultaneous connections occurring. It could provide server-less service in poor network condition. DISS allows users retrieve disaster information from terminals or ICN nodes. During disasters, sharing information timely and effective could protect people from disaster, ensure people's safety.

Information Centric Networking (ICN) had merits in terms of mobility, security, power consumption and network traffic. When a large-scale disaster occurred, the current communication system might be fragile and the server based network service might be unavailable due to the damages, network congestions, and power failure, etc. In this paper, we proposed an ICN based Disaster Information Sharing Service (DISS) [1], [2] system. DISS could provide robust information sharing service. Users could publish disaster information as a content message with the help of our DISS. In addition, by utilizing DISSïs message naming strategy, users could retrieve disaster information even without a server connection. The ICN based DISS could reduce the probability of network congestion when a large number of simultaneous connections occurring. It could provide server-less service in poor network condition. DISS allows users retrieve disaster information from terminals or ICN nodes. During disasters, sharing information timely and effective could protect people from disaster, ensure peopleïs safety.

Despite the numerous benefits brought by device-to-device (D2D) communications, the introduction of D2D into cellular networks poses many new challenges in the resource allocation design because of the co-channel interference caused by spectrum reuse and limited battery life of user equipment's (UEs). Most of the previous studies mainly focus on how to maximise the spectral efficiency and ignore the energy consumption of UEs. In this study, the authors study how to maximise each UE's Energy Efficiency (EE) in an interference-limited environment subject to its specific quality of service and maximum transmission power constraints. The authors model the resource allocation problem as a non-cooperative game, in which each player is self-interested and wants to maximise its own EE. A distributed interference-aware energy-efficient resource allocation algorithm is proposed by exploiting the properties of the nonlinear fractional programming. The authors prove that the optimal solution obtained by the proposed algorithm is the Nash equilibrium of the non-cooperative game. The authors also analyse the tradeoff between EE and SE and derive closed-form expressions for EE and SE gaps.

In 5G research the spectrum efficiency (SE) and energy efficiency (EE) are two crucial issue. Some scholars propose the Massive Multiple-Input Multiple-Output (Massive MIMO) technology as a essential element to achieve the targets. In addition, the non-orthogonal multiple access (NOMA) and mm Wave technologies are proposed towards SE in 5G. In this paper, apart from the previous studies, we study the EE issue while combining the massive MIMO and NOMA together. Which can take advantage of the NOMA for better SE and antenna selection for better EE performance within the background of massive MIMO in 5G.

In order to provide the robust and energy-efficiency contents delivery to the mobile terminals in Information Centric Networking (ICN), this paper proposes a dynamic proactive-scheme and evaluates its performance as an effective mechanism for green mobility in ICN. In our scheme, when a mobile node expresses an Interest for a content then neighbor Aggregation Nodes (possible future points of attachment) also generate the "fake interest" for this content to the Content Provider. As a result, after the handoff, when the mobile node re-issues the same interest, the desired content can be found en-route and can be retrieved immediately. To diminish the ICN energy consumption by utilizing this scheme (the interest needs not to travel to the Content Server), we design different operating modes for the server based on the interest traffic. We verify the effectiveness and reliability of our proposed scheme by simulating the model with ndnSIM.

The information exchange in the power grid has been undergoing through crucial changes. With the application of advanced Information and Communication Technologies (ICT) to the existing power network; the future grid sees incredible enhancements. However the huge amount of data to transfer over the network becomes challenging. Many literatures show the benefits of applying Information-Centric Network to the power system. In this paper we propose an application of 1CN to Smart Grid system. We evaluate the robustness of the ICN over IP.

In recent years, train passengers have been transferring increasing amounts of data using mobile devices. Wireless networks with mobile relay nodes support broadband wireless communications for passengers of such vehicles using backhaul links. However, the mobility management entity reuses the handover of existing user equipment, resulting in the handover of the Long-Term Evolution network being unsuitable for user equipment within the cabins of vehicles traveling at high speed. In this paper, we propose a self-optimizing handover hysteresis scheme with dual mobile relay nodes for wireless networks in high-speed mobile environments. The proposed mechanism tunes the hysteresis and cell individual offset handover parameters based on the velocity of the vehicle and the handover performance indicator, which affects the handover triggering decision and performance. The results of simulations conducted in which the performance of the proposed scheme was compared to that of an existing scheme show that the proposed scheme can reduce the number of radio link failures and service interruptions during handover procedures.

In Information Centric Networking (ICN), besides Off-path caching, On-path caching is an integrated caching solution with-in an ISP's local network. However, in On-path caching, content is cached en-route in the backward path towards the Interest generator and local RENE1/NRS2 (in routing through name resolution) or FIB3 (in name-based routing) is not aware of the cached data. Hence, the most widely used intra-domain routing protocol and their forwarding strategy cannot address all available temporary cached copies of content. Thus, on-path caching strategy usually suffers from either of the two drawbacks-1) too many replications within AS (Autonomous system) which do not add substantial value in terms of cache resource utilization. 2) An attempt to minimize redundancy ends up with the cost of fetching more copy of the same content from the repository (i.e., the closest cache copy is unknown/not en-route). We propose an integrated routing and caching solution which reduces the caching redundancy and maximize the probability of finding nearby cached content, resulting in efficient utilization of available cache resources of ISP's as a whole. We introduce novel concepts of naming the content router and caching the content's cache-route to address the issue. We leverage NDN node architecture and the forwarding plane/strategy (of routing) as well to achieve our goal.

Information Centric Networking (ICN) had merits in terms of mobility, security, power consumption and network traffic. When a large-scale disaster occurred, the current communication system might be fragile and the server based network service might be unavailable due to the damages, network congestions, and power failure, etc. In this paper, we proposed an ICN based Disaster Information Sharing Service (DISS) [1], [2] system. DISS could provide robust information sharing service. Users could publish disaster information as a content message with the help of our DISS. In addition, by utilizing DISSs message naming strategy, users could retrieve disaster information even without a server connection. The ICN based DISS could reduce the probability of network congestion when a large number of simultaneous connections occurring. It could provide server-less service in poor network condition. DISS allows users retrieve disaster information from terminals or ICN nodes. During disasters, sharing information timely and effective could protect people from disaster, ensure peoples safety.

This paper aims to focus on the standardization process and its consequences in the field of information and communication technologies (ICT) , with a view to understanding the significance of the standardization in academia and inclusion to this subject in academic curricula. Particularly, we take the scenario of cellular communication industry and as an evolutionary technology we take CDMA (Code Division Multiple Access) as a case study. Game theory is chosen as a tool for analysis of the business decision of stakeholder of an innovative technology. CDMA' s spread spectrum approach was unique. However, the good technology doesn' t always win out. A good example is VHS ; which is successful and won out the market though technically inferior to Betamax. For the case of CDMA, we explain the case of good technological innovation, strategic management by the innovator and the role of standardization as a pre-requisite to win the market. We designed the game based on the scenario while a technology licensor (Qualcomm) simultaneously works as a product manufacturer and make a role overlapping with the licensee (Motorola, Nokia, Ericson etc) . We also give a brief mathematical analysis with the Stackelberg leadership Game Model for the Qualcomm' s Royalty and Chip business.

In order to address the energy flaw and enhance the energy efficiency of Information Centric Networking (ICN) Architecture, this research proposes an innovated optimal ICN model with adaptive power consumption ability based on the popularity of the content to adapt content router link rate to its real-time utilization for optimizing the ICN router operating power value and based on the interest traffic to the server to select the optimal working mode for the server/content provider. With this dynamic control/adaptive mechanism, the proposed architecture can provide higher reliability with dynamic energy efficiency consumption and better cost-effectiveness for the future ICN infrastructure system to reduce electricity usage, cost and greenhouse gases, then solve global warming issues.

Massive Multiple-Input Multiple-Output (Massive MIMO) has been realized as a promising technology element for 5G wireless mobile communications, in which Spectral Efficiency (SE) and Energy Efficiency (EE) are two critical issues. Prior estimates have indicated that 57% energy consumption of cellular system comes from the operator, mostly used to feed the base station (BS). Yet previously, the User Equipment (UE) is focused on while studying the EE issue instead of BS. In this case, in this paper, an EE scheme that focuses on the optimization of BS energy consumption is proposed. Apart from the previous studies, which divides the coverage area by circuit section, the coverage area is divided by fan section with the help of Propagation theory for zoom in or zoom out. In the proposal, transmission model and parameters related to EE is deduced first. Afterwards, the Cellular Partition Zooming (CPZ) scheme is proposed where the BS can zoom in to maintain the coverage area or zoom out to save the energy. Comprehensive simulation results demonstrate that CPZ presents better EE performance with negligible impact on the transmission rate.

The Large Scale Antenna System is expected to bring significant improvements to overall Communication System Performance. However the use of so many antennas in Massive Multiple Inputs Multiple Outputs (Massive MIMO) architectures highlights the cost implication of the technology. It is therefore possible that Massive MIMO may be deployed using low cost equipment to avoid HUGE implementation costs. The use of Low Cost Equipment will results into significant Radio Frequency Impairments (RF-Impairments) such as Phase Noise, IQ Imbalance and Nonlinearities, which will affect the overall system performance. Among other aspects channel estimations will also be affected since the signal used for these estimations will be affected by the RF-Impairments. This paper analyzes a way to exploit correlation during Minimum Mean Square Error (MMSE) Channel Estimation of a Massive MIMO System in presence of aggregated RF-Impairments (i.e. combined effects of the impairments). Specifically it derived the statistical distribution of the equivalent aggregated error/noise term using statistical identities and uses the derived term to obtain temporal channel estimation error and consequently the correlation matrix necessary to minimizes the channel Mean Square Error (MSE) of the channel estimate.

Providing robust content delivery service, such as Video on Demand, with efficient wireless resource usage is important for mobile users. To achieve this, we have proposed a proactive content caching scheme utilizing transportation systems (e.g., train). Because our previous prototype is immature and has a scalability issue, in this paper, we introduce an efficient transmission mechanism of Interest messages to improve throughput efficiency in mobile NDN, develop two prototypes based on NDN and HTTP, and then evaluate prototype performances by performing larger-scale field experiments on actual commercial railroad line. Evaluations conclude that our system can achieve high efficient content transfer and fully utilize wireless network bandwidth. As a result, our system can provide high-quality video streaming for up to 50 users simultaneously.

In this letter, we investigate the tradeoff between energy efficiency (EE) and spectral efficiency (SE) in device-to-device communications underlaying cellular networks with uplink channel reuse. The resource allocation problem is modeled as a noncooperative game, in which each user equipment is self-interested and wants to maximize its own EE. Given the SE requirement and maximum transmission power constraints, a distributed energy-efficient resource allocation algorithm is proposed by exploiting the properties of the nonlinear fractional programming. The relationships between the EE and SE tradeoff of the proposed algorithm and system parameters are analyzed and verified through computer simulations.

移動中での高速インターネット環境が整備される中,新幹線やリニア新幹線での実用化に向けて無線問題が上がった.今後更なる普及が見込まれるクラウドサービスを支えるためには,更なる安定かつ高速な無線通信環境が要求される.本稿では,GPS(Global Positioning System)の測位誤差を考慮する事で,移動局の位置情報の誤差に対するスループットの低下を補償する一手法を提案する.通信状態に応じて送信および受信アンテナ数を適応的に切り換えるビームマネージメント・アルゴリズムにより,移動局の測位誤差による影響を最小限に抑える事で,平均スループットの改善を得た.

筆者らは,近年のモバイルトラフイックの爆発的な増加に対処するために,交通機関を活用したコンテンツ先回り配信システムを提案している.本稿では,その性能評価をするために,フィールド実験として,試験線を用いた実車両実験を行った.従来の CDN を想定したセルラーによる配信と比較し,先回り配信システムの有効性を明らかにした.

筆者らが研究するSSB-QPSK変復調方式に多値化対策を提案し、SSB-QAM方式を提案した。QPSKモードではrolloff率を0に近づけた場合に4bit/s/Hzとなる。また多値化変調16QAM、64QAMにおいてもOFDMの性能の2倍になることを原理的に示せるとした。本報告では、本提案方式がBit誤り率の劣化要因として及ぼす範囲を検証した。またAWGNに対しては本方式が相関検波と同様の作用を有することで、SSBとしてのCNR劣化作用を克服できることを示した。

筆者らは,近年のモバイルトラフイックの爆発的な増加に対処するために,交通機関を活用したコンテンツ先回り配信システムを提案している.本稿では,その性能評価をするために,フィールド実験として,試験線を用いた実車両実験を行った.従来の CDN を想定したセルラーによる配信と比較し,先回り配信システムの有効性を明らかにした.

コンテンツセントリックネットワーク(Contents Centric Network; CCN)は、従来、ノードを基準として行われていた通信形態をコンテンツを主体として行う形態へと変革させる新しい通信パラダイムである.本文はその特徴を利用して、CCNにおけるVoDサービスについて研究している.そして、新たな効率的キャッシュアルゴリズムの検討を行った。

本論文では、情報通信技術(ICT)のアプローチの近代的な概念を使用して、災害シナリオのコンテンツ中心ネットワーク(CCN)スキームを提示する。コンテンツ中心ネットワークは必要がある場所に関連するコンテンツをプッシュすることを特徴として新しいネットワークである。そのキャッシュとリポジトリ機能を使用して、バックボーンネットワークの輻輳や遅延を低減することができる。災害シナリオでは、完備していないネットワーク環境のため、通信障害が発生しやすい。また、被災地の内と外両側から通常より災害に関する情報配信の高い需要、がバックボーンネットワークに大きな圧力をもたらす。事前キャッシュされた内容を詰め込みするリポジトリ機能を持つコンテンツ中心ネットワークは、キャッシュヒットとホップ距離で、堅牢性と高い性能を表す。バックボーンネットワークにおける輻輳やスループットの圧力を解放に活用できる。

筆者らが研究するSSB-QPSK変復調方式において、新たな検波方式を考案した。この結果、最大の課題の一つであった隣接シンボル間干渉を理論的に皆無にした。これにより希望波の振幅情報をほぼ干渉なく復調できることとなり、シンボル信号の多値化が可能となり、OFDM方式の持つ周波数利用効率2bit/s/Hzに匹敵する新たな変復調方式を具現化した。NyquistフィルタのRolloff率を0に近づけた場合の周波数利用効率は4bit/s/Hzとなる。今後、SSBキャリアのインターリーブ化を図りOFDMタイプのマルチキャリア化による新変復調方式を検討する。

In this paper, we present a new Wi-Fi roaming selection scheme as a solution for macro-cell traffic offloading. The idea is to take advantage of the Access Network Discovery and Selection Function (ANDSF) policies and the IEEE 802.11k standard for Wi-Fi access point (AP) selecting process. Although ANDSF can provide the list of candidate APs with preferred selection policies, due to the fact that ANDSF's selection policies are static and are not based on the real-time network condition, it cannot be considered as a solution for traffic steering and offloading issue in heterogeneous network. In our proposed scheme for Wi-Fi offloading, we address this issue by taking into account the real-time traffic load of Wi-Fi AP as one criterion for selection. We simulate and verify the proposed scheme on NCTUNS 6.0. The simulation result shows that our scheme can effectively offload the data traffic from cellular network to Wi-Fi and improve the overall network throughput.

Despite the numerous benefits brought by device-to-device (D2D) communications, user equipments (UEs) are typically handheld devices with limited battery life and can quickly run out of battery if power consumption is ignored in the system design. Compared to previous works that have not taken power consumption into consideration, we model the utility function as a weighted sum of achievable transmission rate, power consumption, and interference revenue (or cost) based on multi-objective optimization (MOO) methods. The resource allocation process is modeled as a two-stage Stackelberg game with transmission power and quality of service (QoS) constraints, in which cellular UEs are game leaders who charges D2D UEs for reusing channels, and D2D UEs are game followers who buy channel resources from cellular UEs. Simulation results show the effectiveness of the proposed algorithm and how the system parameters affect the pricing and transmission power strategies.

In this paper, we consider the application scenario where multiple Base Stations (BSs) cooperate to transmit signals to a mobile terminal in the same frequency and any of the cooperative BSs is allowed to enter into sleeping mode to save energy. The mobile terminal employs the Joint Maximum Likelihood Sequence Estimation (JMLSE) based Joint Signal Detection (JSD) to simultaneously detect multiple co-channel signals and judge whether a cooperative BS is active or not. The detection error probability of JSD is analyzed in this paper. For the case of BS sleeping, the error probability is computed based on a tentative modulation scheme which incorporates the M constellation points of conventional M-QAM and the additional constellation point 0. For the case of BS cooperation, the error probability bounds are derived based on a genie-aided receiver, and a new Tighter Lower Bound (TLB) is derived by replacing the genie with a less generous one. Simulation results have verified that the computed error probability can provide a rapid and accurate estimation of the Symbol Error Rate (SER) performance.

The introduction of device-to-device (D2D) into cellular networks poses many new challenges in the resource allocation design due to the co-channel interference caused by spectrum reuse and limited battery life of user equipments (UEs). In this paper, we propose a distributed interference-aware energyefficient resource allocation algorithm to maximize each UE's energy efficiency (EE) subject to its specific quality of service (QoS) and maximum transmission power constraints. We model the resource allocation problem as a noncooperative game, in which each player is self-interested and wants to maximize its own EE. The formulated EE maximization problem is a nonconvex problem and is transformed into a convex optimization problem by exploiting the properties of the nonlinear fractional programming. An iterative optimization algorithm is proposed and verified through computer simulations.

This paper proposes the effective data gathering and energy efficient communication scheme for Wireless Sensor Networks employing Unmanned Aerial Vehicle. In this scheme, we minimize the number of redundant sensors communicating with UAV by assigning the sensors inside the coverage area of UAV's beacon signal into different priority groups. Once the priority segments, Circularly Optimized Frame Selection (COFS), are defined, data communication is handled from higher to lower transmission priority frame sequentially. The work presented in the paper is based on multi-hop approach. Therefore, the plausible algorithms employing the scheme COFS are proposed to engage in effective data collection. As a result, both the proposed scheme and algorithms are significant to obtain low energy consumption as well as increase the lifetime of sensors inside the network. The energy consumption model is also presented. This study is confirmed by simulating the WSN-UAV system employing our proposed model.

This paper proposes the effective data gathering and energy efficient communication scheme for Wireless Sensor Networks employing Unmanned Aerial Vehicle. In this scheme, we minimize the number of redundant sensors communicating with UAV by assigning the sensors inside the coverage area of UAV's beacon signal into different priority groups. Once the priority segments, Circularly Optimized Frame Selection (COFS), are defined, data communication is handled from higher to lower transmission priority frame sequentially. The work presented in the paper is based on multi-hop approach. Therefore, the plausible algorithms employing the scheme COFS are proposed to engage in effective data collection. As a result, both the proposed scheme and algorithms are significant to obtain low energy consumption as well as increase the lifetime of sensors inside the network. The energy consumption model is also presented. This study is confirmed by simulating the WSN-UAV system employing our proposed model.

The Advanced Metering Infrastructure (AMI) is the core component in Smart Grid. The cyber security is one of the major concerns and challenges should be prior considered. The Information Centric Networking (ICN) is a promising architecture for the future Internet that disseminates content based on named data instead of named hosts. It will be involved into Smart Grid because its excellent congestion control and self-security can enable more scalable, secure, collaborative and pervasive networking. This paper aims at proposing an Information Centric AMI (ICN-AMI) structure and a novel key management scheme (KMS) for a large number of smart meters (SMs) in this system to ensure confidentiality, integrality and authentication. To validate the scheme, the security analysis, comparisons and NDNsim simulation are done to demonstrate that the proposed ICN-KMS is possible solution for ICN-AMI system.

Providing robust content delivery along with efficient wireless resource usage is important for next generation wireless networks. To achieve this, we propose a proactive content caching scheme utilizing transportation systems, especially trains. In our system, we place content servers with CCN capability to every train and station. Segments of video contents are pre-cached by the station servers before trains arrive at stations. Trains receive the contents via high-speed wireless transport while they stop at the stations. We develop a prototype system based on IP and CCN Hybrid protocols. We evaluate its performance by field experiment and compare with traditional CDN scenarios using cellular networks. Evaluations conclude that our system can achieve high-speed and high-reliable video delivery without freezing.

In the long term evolution (LTE), Relay node architectures included in order to increase the coverage and system capacity. But designed in the LTE-A and release 12, the Relay node architectures supported mobility. An LTE system based on the network-controlled hard handoff and handoff reuses existing user equipment. In this paper, we propose an adaptive handoff hysteresis scheme with a simplified cost function considering some dominant factors for Mobile Relay such as the load difference target cells, the velocity, and the service type. The performances of the traditional handoff scheme and the proposal are analyzed and compared in details.

In Japan a feed-in tariff scheme has promoted the utilization of photovoltaic power generators in combination with electric batteries. Although many researchers have assessed the operations of grid-connected photovoltaic systems with electric batteries, little attention has been paid to the impact of the electric batteries' degradation characteristics. This paper presents an evaluation of the operation of a grid-connected photovoltaic/electric battery system in a house from energy saving and economy viewpoints. We constructed a long-term operational optimization model considering the degradation characteristics of the electric battery. This model contains two objective functions: energy saving and operating cost. We set a scenario of power rate and photovoltaic/battery system configurations. In order to reveal the optimal operational strategy of the photovoltaic/battery system, the multi-objective optimization problem was solved. As a result, pareto optimal solutions were obtained, and trade-off relationships between economy and energy saving are presented. In this study, the utilization of the grid-connected photovoltaic system with an electric battery was expected to be effective in an energy saving priority operation.

Advanced Metering Infrastructure (AMI), as the totality of systems and networks to measure, collect, store, analyze, and use energy usage data, is supposed to the key component that should be preferentially constructed for smart grid. In the meanwhile, content-centric networking (CCN) is perceived as a promising approach where the content itself becomes the core of communication instead of the address or location in the future internet research. Based on its caching advantage, it is widely believed that CCN can effectively reduce the AMI network bandwidth. This paper aims to apply the CCN approach on AMI system, which is called CCN-AMI. To the best of our knowledge, this is the first attempt to distribute contents or requests based on CCN in AMI system. Moreover, a simulation-based performance evaluation is employed to evaluate the effectiveness of the proposed CCN-AMI approach in traffic control for developing AMI system in smart grid.

The contributions of this paper are twofold. Firstly, we analyze the decision making problem of caching contents by the network players of Information Centric Networking (ICN) from a game theoretic perspective. We also mention a possible content distribution model for ICN. By our proposed game theory, different network players can find the optimality taking into consideration which benefits them with optimum revenue. Secondly, we present a solution for Live Streaming Media broadcast in ICN and analyze the economic part with a decision tree. We believe, our paper clearly shows the economic incentives for major network players which can stand as a motivation to achieve the faster accommodation of ICN architecture. Besides, we identify some standardization issue in ICN architecture and we emphasize on the need for a common standard for content routers (CR) so that as a node in the ICN, CR ensure scalable content delivery as well as its functionalities match with the Internet open standard philosophy.

The Advanced Metering Infrastructure (AMI) is the core component in Smart Grid. The cyber security is one of the major concerns and challenges should be prior considered. The Information Centric Networking (ICN) is a promising architecture for the future Internet that disseminates content based on named data instead of named hosts. It will be involved into Smart Grid because its excellent congestion control and self-security can enable more scalable, secure, collaborative and pervasive networking. This paper aims at proposing an Information Centric AMI (ICN-AMI) structure and a novel key management scheme (KMS) for a large number of smart meters (SMs) in this system to ensure confidentiality, integrality and authentication. To validate the scheme, the security analysis, comparisons and NDNsim simulation are done to demonstrate that the proposed ICN-KMS is possible solution for ICN-AMI system.

災害時には災害情報の発信と受信のために,膨大なアクセスが短時間にネットワークに対して行われる.それら通信サービスに対応するための通信処理能力が大幅に不足することから,通信途絶等の状態が生じたことを踏まえ,通信ネットワークの耐災害性強化に向けるネットワークを統合的に構成することが必要である.本研究では,ネットワーク全体のトラヒックを削減するには,コンテンツ中心ネットワークを用い,ルータ上でキャッシュを行う方法を検討する.さらに,キャッシュヒット率の向上を図るために,パスキャパシティとコンテンツ人気度を考慮するキャッシュを適切に多重化するキャッシュデシジョンポリシの提案とその評価を行う.

In this paper, we present the Intelligent Hybrid MAC (IH-MAC), a novel low power with quality of service guaranteed medium access control protocol for wireless sensor networks (WSNs). The IH-MAC achieves high energy efficiency under wide range of traffic load. It ensures shorter latency to critical and delay-sensitive packets. The IH-MAC protocol achieves high channel utilization during high traffic load without compromising energy efficiency. The IH-MAC does it by using the strength of CSMA and TDMA approach with intelligence. The novel idea behind the IH-MAC is that it uses both the broadcast scheduling and link scheduling. Depending on the network loads, the IH-MAC protocol dynamically switches from broadcast scheduling to link scheduling and vice versa in order to achieve better efficiency. The scheduling is done in the IH-MAC with a novel decentralized approach where the nodes locally use the clock arithmetic to find the time slot, allocated for it. Furthermore, the IH-MAC uses Request-To-Send, Clear-To-send handshakes with methods for adapting the transmit power to the minimum level necessary to reach the intended neighbor. Thus, the IH-MAC reduces energy consumption by suitably varying the transmit power. The IH-MAC also uses the concept of parallel transmission that further reduces delay. The analytical and simulation results corroborate the theoretical idea, and show the efficiency of our proposed protocol.

In this paper, we present the Intelligent Hybrid MAC (IH-MAC), a novel low power with quality of service guaranteed medium access control protocol for wireless sensor networks (WSNs). The IH-MAC achieves high energy efficiency under wide range of traffic load. It ensures shorter latency to critical and delay-sensitive packets. The IH-MAC protocol achieves high channel utilization during high traffic load without compromising energy efficiency. The IH-MAC does it by using the strength of CSMA and TDMA approach with intelligence. The novel idea behind the IH-MAC is that it uses both the broadcast scheduling and link scheduling. Depending on the network loads, the IH-MAC protocol dynamically switches from broadcast scheduling to link scheduling and vice versa in order to achieve better efficiency. The scheduling is done in the IH-MAC with a novel decentralized approach where the nodes locally use the clock arithmetic to find the time slot, allocated for it. Furthermore, the IH-MAC uses Request-To-Send, Clear-To-send handshakes with methods for adapting the transmit power to the minimum level necessary to reach the intended neighbor. Thus, the IH-MAC reduces energy consumption by suitably varying the transmit power. The IH-MAC also uses the concept of parallel transmission that further reduces delay. The analytical and simulation results corroborate the theoretical idea, and show the efficiency of our proposed protocol.

近年、無線技術の進歩に伴い無線センサ端末の小型化,低価格化および標準化の進展が著しいである.スマートグリッド分野において、膨大な数の住宅やビルに対して、情報を収集する無線センサネットワーク技術が注目を集めている.私は各家庭やビルなどにある環境清報を長期間の観測及び監視をするため、大規模なセンサネットワークに対応できるデータの処理方法が必要だと考えている.スマートグリッド分野における、センサ収集データの処理方法による高精度のデータを取得し、最適な省エネルギー手法やデマンドレスポンス手法が生み出すことができる.本提案は、スマートグリットのHEMSとBEMS分野における、センサ収集データの処理方法に注目し、従来の処理方法より高い精度なデータ処理を提案し、提案する処理方法で評価を行い、従来型のデータ処理方法より優れた事が分かった.

過去、日本の農業の70%以上を占めしていた里山は、天然資源の使用変化と社会問題により相次いて消失した。里山の復興に目を置き、筆者は農業におけるワイヤレス・センサ・ネットワークを用いた温度、湿度の監視と制御を提案する。本稿では、効果的なデータ収集や省エネーのクラスタリングスキームを確保できる方法について研究を行った結果、センサノートが定期的なデータ収集により良く対応できることを明らかにした。その結論によって、人口の減少に対応し里山の生産性と効率性を向上させることが可能になった。

本稿では、情報通信技術(ICT)のアプローチの近代的な概念を使用して情報共有システムを提案する。濃縮された首都圏の災害は、人間の生命や財産に深刻な被害の重大な損失を引き起こす。災害が発生すると被害地域外の救助者は避難所の場所はそれほど頻繁に提供されるより集約された情報を必要とするなどのサービスを提供しながら、被害者は、リアルタイムで離散的事件の情報を受信する必要があります。スマートフォンの需要は驚異的な成長、私たちの災害管理システムのウェブサービスは、スマートフォンに提供することができたので。さらに救助を評価するために、モバイルユーザーがワイヤレス測位技術を通じて現在位置を取得し、システムに災害関連情報をアップロードすることもできますが、この論文では、情報共有システムの設計について説明し、損傷領域外の救助者かウェブサイト上でこれらのデータを確認する操作。

Wireless communication technologies bring numerous bene. ts for smart grid applications including lower cost, more. exibility, easier installation, etc. In this paper, the performance of wireless local area network (WLAN) under impulse electromagnetic interference (EMI) in a substation is evaluated. Simulation results have demonstrated that the impulsive EMI causes more severe degradations compared with additive white Gaussian noise (AWGN), especially when the signal to interference plus noise ratio (SINR) is high. Although multiple-antenna based diversity schemes achieve better performance than the single-antenna scheme, the diversity gain is not sufficient to compensate for the performance loss caused by the impulsive EMI. Therefore, how to mitigate the impulsive EMI is essential for deploying WLAN systems in a substation. This paper also summarized conventional interference mitigation techniques, and their adaptability to the impulsive EMI. The analysis provides an insight to future research.

In this paper, we propose an average connectivity degree cluster (ACDC) scheme gossip algorithm to improve the convergence speed and the accuracy of the consensus, when a common decision is needed for a certain phenomenon in a distributed network. We analyze the effects of the initial value, the network topology (regular and irregular), and the number of clusters on the algorithm convergence rate as well as the accuracy of the value when reaching consensus. A utility function is developed based on two parameters, iteration and relative error, to help the network designers make an optimal decision based on their requirements. An irregular sensor model which is based on the degree of irregular (DOI) radius is introduced to evaluate the robustness of the algorithm. The simulation results demonstrate that for any initial value and network topology, the proposed ACDC gossip algorithm can yield results that are 50% closer to the real average value than the referenced standard gossip and grid cluster gossip algorithms. With different DOI values, our ACDC gossip algorithm can still reach lower relative error compared with other gossip algorithms, which demonstrates that our algorithm is robust enough to be executed in the network. © 2013 Yanwei Li et al.

In this paper, we propose an average connectivity degree cluster (ACDC) scheme gossip algorithm to improve the convergence speed and the accuracy of the consensus, when a common decision is needed for a certain phenomenon in a distributed network. We analyze the effects of the initial value, the network topology (regular and irregular), and the number of clusters on the algorithm convergence rate as well as the accuracy of the value when reaching consensus. A utility function is developed based on two parameters, iteration and relative error, to help the network designers make an optimal decision based on their requirements. An irregular sensor model which is based on the degree of irregular (DOI) radius is introduced to evaluate the robustness of the algorithm. The simulation results demonstrate that for any initial value and network topology, the proposed ACDC gossip algorithm can yield results that are 50% closer to the real average value than the referenced standard gossip and grid cluster gossip algorithms. With different DOI values, our ACDC gossip algorithm can still reach lower relative error compared with other gossip algorithms, which demonstrates that our algorithm is robust enough to be executed in the network. © 2013 Yanwei Li et al.

The extensive deployment of femtocells introduces co-channel interference to the macro cell-edge users (MCEUs), which degrades the throughput improvement of the total network. In this paper, we consider the scenario in which the femtocell base station (FBS) allows the hybrid access of MCEUs on the condition that the MCEUs rent the power resource from it. However, the FBS is power limited. If almost all of its power is used to serve the MCEUs and its original femtocell users (FUEs), when newly authoritized FUEs are switched on, there will be little power left to serve these newly authoritized FUEs. In this situation, the FBS can select one MCEU as a relay to coordinate its information transmission to the FUE. To reward the cooperation of the MCEUs, the FBS will agree to support the service of MCEUs without charging. Stackelberg game is used to find the optimal power and price value for this procedure. An MCEU relay selection criterion is proposed for the FBS. The optimal power that the MCEU can obtain from the FBS and the power that the MCEU can obtain from the FBS and the power that the MCEU can share with the FUEs are obtained. The simulation results show that the throughputs of both the FUEs and the MCEUs are improved.

In previous works, a blind single antenna interference cancellation (SAIC) algorithm named least mean squareblind joint maximum likelihood sequence estimation (LMS-BJMLSE) has been proposed for OFDM systems. It is blind with respect to interference and is able to cancel interference by only one receive antenna. However, LMS-BJMLSE requires a long training sequence (TS) for channel estimation, which greatly reduces the transmission efficiency. Furthermore, since TS is not available in 4G LTE systems, LMS-BJMLSE can not be applied directly. In this paper, in order to solve this problem, a SINR and symbol position weight adaptive algorithm is proposed, and named as adaptive LMS-BJMLSE (ALMS-BJMLSE). For each slot, ALMS-BJMLSE dynamically decides the number of antennas used for interference cancellation and adjusts the step size, based on estimated SINR conditions and symbol position weight. Simulation results demonstrate that ALMS-BJMLSE achieves a much better balance between performance and transmission efficiency compared to the conventional LMS-BJMLSE algorithm, and can be applied for 4G LTE systems.

We propose a resource allocation method which guarantees a throughput of each mobile station (MS) in a Base Station (BS) cooperated MIMO. A previously proposed method for guaranteeing MS throughputs allocates resource to MSs which can not guarantee throughput with a bad channel quality. Our method excludes MSs with a bad channel quality and allocates resource to the other MSs with a good channel quality. The simulation result showed our method guaranteed more MSs' throughput and achieved a higher system throughput than the previous method.

This paper aims at improving the demodulation performances of Four-element Single Sideband signals by proposing a new receiver structure involving an Inter-Signal Interference cancellation filter. The filter makes use of the estimated symbols generated by the receiver to approximate the interference between multiplexed signals inherent to the use of low complexity Hilbert Transform filters at the transmitter. Simulation results show that the new receiver structure performs better than the one formerly proposed in early works on this topic.

The involvement of smart grid in home and building automation systems has led to the development of diverse standards for interoperable products to control appliances, lighting, energy management and security. Smart grid enables a user to control the energy usage according to the price and demand. These standards have been developed in parallel by different organizations, which are either open or proprietary. It is necessary to arrange these standards in such a way that it is easier for potential readers to easily understand and select a suitable standard according to their functionalities without going into the depth of each standard. In this paper, we review the main smart grid standards proposed by different organizations for home and building automation in terms of different function fields. In addition, we evaluate the scope of interoperability, benefits and drawbacks of the standard.

In previous works, a blind single antenna interference cancellation (SAIC) algorithm named least mean squareblind joint maximum likelihood sequence estimation (LMS-BJMLSE) has been proposed for OFDM systems. It is blind with respect to interference and is able to cancel interference by only one receive antenna. However, LMS-BJMLSE requires a long training sequence (TS) for channel estimation, which greatly reduces the transmission efficiency. Furthermore, since TS is not available in 4G LTE systems, LMS-BJMLSE can not be applied directly. In this paper, in order to solve this problem, a SINR and symbol position weight adaptive algorithm is proposed, and named as adaptive LMS-BJMLSE (ALMS-BJMLSE). For each slot, ALMS-BJMLSE dynamically decides the number of antennas used for interference cancellation and adjusts the step size, based on estimated SINR conditions and symbol position weight. Simulation results demonstrate that ALMS-BJMLSE achieves a much better balance between performance and transmission efficiency compared to the conventional LMS-BJMLSE algorithm, and can be applied for 4G LTE systems.

The involvement of IEEE 802.15.4 Wireless Sensor Networks (WSNs) in diverse applications has made the realistic analysis of sensor power dissipation in distributed network environments an essential research issue. In this paper, we propose and thoroughly analyze a power dissipation model for Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) based IEEE 802.15.4 distributed multi-hop WSNs. Our model takes the loss rate of frames, neighbor sensors density in communication range of a sensor, number of hops, distance of source to the sink, and density of the network into account. We evaluate the impact of these factors on overall power dissipation. We also perform comprehensive analysis of overheads caused by message routing through multi-hop distributed networks. We validate our proposed model through Monte Carlo simulations. Results show that our power dissipation model is more realistic compared to other proposed models in terms of accuracy and multiplicity of the environments.

本論文は,複数基地局環境において,個々の端末のスループットを保証可能な基地局制御装置(RNC:Radio Network Controller)を用いた集約的な動的チャネル割当方式(DCA:Dynamic Channel Allocation)について提案する.これまで複数基地局環境において提案されたDCAとしては,個別の端末のスループットを考慮せずにシステム全体の端末のスループットの和を最大化する方式や,ある大きさ以上の基地局間干渉波を抑止する条件のもとでシステム全体の端末のスループットを最大化する方式はあったが,個々の端末のスループットを保証した上でシステム全体における端末のスループットの和を最大化するようなDCAの方式は提案されていなかった.本論文では,提案方式についてシミュレーションを実施し,あらかじめ設定したスループットを保証するチャネル割当が実現可能なことを示す.また従来方式によるシミュレーション結果と比較を行い,提案方式の有効性を示す.

The involvement of IEEE 802.15.4 Wireless Sensor Networks (WSNs) in diverse applications has made the realistic analysis of sensor power dissipation in distributed network environments an essential research issue. In this paper, we propose and thoroughly analyze a power dissipation model for Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) based IEEE 802.15.4 distributed multi-hop WSNs. Our model takes the loss rate of frames, neighbor sensors density in communication range of a sensor, number of hops, distance of source to the sink, and density of the network into account. We evaluate the impact of these factors on overall power dissipation. We also perform comprehensive analysis of overheads caused by message routing through multi-hop distributed networks. We validate our proposed model through Monte Carlo simulations. Results show that our power dissipation model is more realistic compared to other proposed models in terms of accuracy and multiplicity of the environments.

With Wireless Sensor Networks (WSNs) involving in diverse applications, the realistic analysis of energy consumption of a sensor node in an error-prone network environment is emerging as an elementary research issue. In this paper, we introduce a Distributed Communication Model (DCM) that can accurately determine the energy consumption through data communication from source to destination in error-prone network environments. The energy consumption is affected with the quality of link, which is characterized by symmetry, directivity, instability, and irregularity of the communication range of a sensor node. Due to weak communication links, significant packet loss occurs that affects the overall energy consumption. While other models unable to determine energy consumption due to lossy links in error-prone and unstable network environments, DCM can accurately estimate the energy consumption in such situations. We also perform comprehensive analysis of overheads caused by data propagation through multi-hop distributed networks. We validate DCM through both simulations and experiments using MICAz motes. Similarity of the results from energy consumption analysis with both simulations and experimentations shows that DCM is realistic, compared to other models in terms of accuracy and diversity of the environments.

Many sensor applications are aimed for mobile objects, where conventional routing approaches of data delivery might fail. Such applications are habitat monitoring, human probes or vehicular sensing systems. This paper targets such applications and proposes lightweight proactive distributed data collection scheme for Mobile Sensor Networks (MSN) based on the theory of thermal fields. By proper mapping, we create distribution function which allows considering characteristics of a sensor node. We show the functionality of our proposed forwarding method when adapted to the energy of sensor node. We also propose enhancement in order to maximize lifetime of the sensor nodes. We thoroughly evaluate proposed solution and discuss the tradeoffs.

Many sensor applications are aimed for mobile objects, where conventional routing approaches of data delivery might fail. Such applications are habitat monitoring, human probes or vehicular sensing systems. This paper targets such applications and proposes lightweight proactive distributed data collection scheme for Mobile Sensor Networks (MSN) based on the theory of thermal fields. By proper mapping, we create distribution function which allows considering characteristics of a sensor node. We show the functionality of our proposed forwarding method when adapted to the energy of sensor node. We also propose enhancement in order to maximize lifetime of the sensor nodes. We thoroughly evaluate proposed solution and discuss the tradeoffs.

Due to the reuse factor reduction, the same frequencies are reused in adjacent neighboring cells, which causes an attendant increase in co-channel interference (CCI). CCI has already become the limiting factor in the performance of orthogonal frequency division multiplexing (OFDM) based cellular systems. Joint maximum likelihood sequence estimation (JMLSE) based interference cancellation algorithms have been under intense research. However, despite the fact that the error probability of JMLSE is critical for analyzing the performance, to the best of our knowledge, the mathematical expression has not been derived for MQAM-OFDM yet. Direct computation of the error probability involves integrating a multi-dimensional Gaussian distribution that has no closed-form solution. Therefore, an alternative way is to upper and lower bound the error probability with computable quantities. In this paper, firstly, both the upper and the conventional lower error probability bounds of JMLSE are derived for MQAM-OFDM systems based on a genie-aided receiver. Secondly, in order to reduce the gap between the conventional lower bound and the simulation results, a tighter lower bound is derived by replacing the genie with a less generous one. Thirdly, those derived error probability bounds are generalized to the receiver diversity scheme. These error probability bounds are important new analytical results that can be used to provide rapid and accurate estimation of the BER performance over any MQAM scheme and an arbitrary number of interferers and receive antennas.

Many sensor applications are aimed for mobile objects, where conventional routing approaches of data delivery might fail. Such applications are habitat monitoring, human probes or vehicular sensing systems. This paper targets such applications and proposes lightweight proactive distributed data collection scheme for Mobile Sensor Networks (MSN) based on the theory of thermal fields. By proper mapping, we create distribution function which allows considering characteristics of a sensor node. We show the functionality of our proposed forwarding method when adapted to the energy of sensor node. We also propose enhancement in order to maximize lifetime of the sensor nodes. We thoroughly evaluate proposed solution and discuss the tradeoffs.

Due to the reuse factor reduction, the attendant increase in co-channel interference (CCI) becomes the limiting factor in the performance of the orthogonal frequency division multiplexing (OFDM) based cellular systems. In the previous work, we proposed the least mean square-blind joint maximum likelihood sequence estimation (LMS-BJMLSE) algorithm, which is effective for CCI cancellation in OFDM systems with only one receive antenna. However, LMS-BJMLSE requires a long training sequence (TS) for channel estimation, which reduces the transmission efficiency. In this paper, we propose a subcarrier identification and interpolation algorithm, in which the subcarriers are divided into groups based on the coherence bandwidth, and the slowest converging subcarrier in each group is identified by exploiting the correlation between the mean-square error (MSE) produced by LMS and the mean-square deviation (MSD) of the desired channel estimate. The identified poor channel estimate is replaced by the interpolation result using the adjacent subcarriers' channel estimates. Simulation results demonstrate that the proposed algorithm can reduce the required training sequence dramatically for both the cases of single interference and dual interference. We also generalize LMS-BJMLSE from single antenna to receiver diversity, which is shown to provide a huge improvement.

In the previous work, a single antenna interference cancellation (SAIC) algorithm named least mean square-blind joint maximum likelihood sequence estimation (LMS-BJMLSE) has been proposed. However, LMS-BJMLSE requires a long training sequence (TS) for channel estimation, which reduces the transmission efficiency. In another work, in order to solve this problem, a subcarrier identification and interpolation algorithm was proposed, in which the slowly converging subcarriers are identified by exploiting the correlation between the mean-square error (MSE) produced by LMS and the mean-square deviation (MSD) of the desired channel estimate. However, this correlation relationship was only found based on simulation results and no clear mathematical proof was given. The performance of the algorithm was only evaluated for the case of single interference. In this paper, the mathematical proof of the correlation relationship between MSE and MSD is given. Furthermore, we generalize LMS-BJMLSE from single antenna to receiver diversity, which is shown to provide a huge improvement over single antenna. The performance of LMS-BJMLSE is also evaluated for the case of dual interference.

The wireless communication system is evolving towards a ubiquitous wireless network in which multiple-radio devices can roam anytime and anywhere across different access networks. Minimal latency and low packet loss ratio during handover (HO) are the indispensable requirements to reduce service disruption and support real-time services. However, minimizing service disruption is a challenging issue to multiple access networks since HO latency is much higher than that of homogeneous networks. Link layer trigger or layer 2 trigger has been proposed to address this issue. Nevertheless, the precise timing and definitive criteria for initiating L2 trigger which can greatly affect the handover performance is not specified. This paper considers the issue of how to timely initiate handover decision from the link layer by using adaptive filtering algorithm to predict forthcoming received signal. Particularly, we propose Recursive Least Squares (RLS) as the predictive method for layer 2 triggering and compare its performance with various conventional filtering techniques. A simulation in which the proposed predictive algorithm is implemented to a handover scenario from Wi-Fi to WIMAX is also presented. Our numerical analysis and simulation results show that the proposed algorithm can achieve better performance than that of the other algorithms and can be used to enhance the handover performance in heterogeneous wireless networks.

This paper proposes a study of performances of the Orthogonal Four Single Sideband elements modulation previously proposed by Ohta [1]. Realistic parameters such as receiver noise and various channel effects are introduced in the derivation of the modulation. Transmission of two QPSK signals multiplexed in one 4-SSB (Single Sideband) signal over OFDM (Orthogonal frequency-division multiplexing) is considered and a demodulation process exploiting a turbo equalizer is presented. Computer simulations are used to verify the performances of the proposed modulation scheme. Results show that 4-SSB QPSK signal over OFDM can achieve performances close to QPSK-OFDM scheme while carrying twice more information, provided perfect channel equalization. However, we also show that in a non-ideal equalization case, performances of 4-SSB QPSK OFDM become highly sensitive to channel effects.

Peer-to-Peer file sharing, computing and communication services are widely used by internet community and thoroughly studied by academia. However, main utilization of such services is in the wired networks due to several significant issues in the wireless world like connectivity, bandwidth, battery, unwillingness of cellular operators, etc. In the recent years, offering femtocell access points to subscribers became very promising business model for cellular operator. It also opens space for a variety of new services at the users premises. In this paper, we propose novel architecture for mobile peer-to-peer file sharing based on the femtocell deployment and describe a role of the femtocell in such scenario. We also describe traditional architecture and previously proposed solutions for mobile P2P. We evaluate these approaches and clearly show that the femtocell plays significant role and moves mobile P2P services into reality. We also discuss several current issues which can be easily solved by this architecture.

The wireless communication system is evolving towards a ubiquitous wireless network in which multiple-radio devices can roam anytime and anywhere across different access networks. Minimal latency and low packet loss ratio during handover (HO) are the indispensable requirements to reduce service disruption and support real-time services. However, minimizing service disruption is a challenging issue to multiple access networks since HO latency is much higher than that of homogeneous networks. Link layer trigger or layer 2 trigger has been proposed to address this issue. Nevertheless, the precise timing and denitive criteria for initiating L2 trigger which can greatly affect the handover performance is not specified. This paper considers the issue of how to timely initiate handover decision from the link layer by using adaptive filtering algorithm to predict forthcoming received signal. Particularly, we propose Recursive Least Squares (RLS) as the predictive method for layer 2 triggering and compare its performance with various conventional filtering techniques. A simulation in which the proposed predictive algorithm is implemented to a handover scenario from Wi-Fi to WIMAX is also presented. Our numerical analysis and simulation results show that the proposed algorithm can achieve better performance than that of the other algorithms and can be used to enhance the handover performance in heterogeneous wireless networks. © 2011 IEEE.

In the previous work, a single antenna interference cancellation (SAIC) algorithm named least mean square-blind joint maximum likelihood sequence estimation (LMS-BJMLSE) has been proposed. However, LMS-BJMLSE requires a long training sequence (TS) for channel estimation, which reduces the transmission efficiency. In another work, in order to solve this problem, a subcarrier identification and interpolation algorithm was proposed, in which the slowly converging subcarriers are identified by exploiting the correlation between the mean-square error (MSE) produced by LMS and the mean-square deviation (MSD) of the desired channel estimate. However, this correlation relationship was only found based on simulation results and no clear mathematical proof was given. The performance of the algorithm was only evaluated for the case of single interference. In this paper, the mathematical proof of the correlation relationship between MSE and MSD is given. Furthermore, we generalize LMS-BJMLSE from single antenna to receiver diversity, which is shown to provide a huge improvement over single antenna. The performance of LMS-BJMLSE is also evaluated for the case of dual interference. © 2011 IEEE.

This paper proposes a study of performances of the Orthogonal Four Single Sideband elements modulation previously proposed by Ohta [1]. Realistic parameters such as receiver noise and various channel effects are introduced in the derivation of the modulation. Transmission of two QPSK signals multiplexed in one 4-SSB (Single Sideband) signal over OFDM (Orthogonal frequency-division multiplexing) is considered and a demodulation process exploiting a turbo equalizer is presented. Computer simulations are used to verify the performances of the proposed modulation scheme. Results show that 4-SSB QPSK signal over OFDM can achieve performances close to QPSK-OFDM scheme while carrying twice more information, provided perfect channel equalization. However, we also show that in a non-ideal equalization case, performances of 4-SSB QPSK OFDM become highly sensitive to channel effects.

Performance evaluation in terms of energy conservation and data reliability of the IEEE 802.15.4 multi-hop communications in error-prone Wireless Sensor Networks (WSNs) is an emerging research issue. In order to accurately evaluate the energy consumption of a sensor node and ultimately the lifetime of WSNs, it is highly desired to thoroughly analyze data reliability through variety of aspects. In this paper, we analyze data reliability in the IEEE 802.15.4 multi-hop communications in error-prone WSNs, by assessing the channel quality using both physical and logical channel quality estimators with different set of parametric values of IEEE 802.15.4 Medium Access Control (MAC) protocol. On the basis of these estimators, we approximate the energy consumption of a sensor node. We also analyze the overheads caused by packet forwarding in the multi-hop WSNs. Simulation results indicate that although physical channel quality estimators are dependent on hardware characteristics, they show better performance in terms of energy consumption and successful data delivery compared to logical channel quality estimators.

This paper proposes a hybrid network scheme combining ad-hoc networks into cellular networks. The scheme is aimed to help the networks to recover to service as much as possible after a disaster strike, by maintaining the connection between Base Stations (BSs) and nodes via multi-hopping, where if a node cannot connect to a BS directly, it switches its working mode from cellular mode to ad-hoc mode. A location-based routing protocol has been proposed for building a route from the node to the BS. Simulation results shows that even if only a small part of the nodes can directly connect to a BS, most of the nodes can find a route to a BS via multi-hopping. And it is found that it outperforms a previously proposed solution which is via beaconing in terms of resistance to mobility.

A handoff algorithm with the criterion of linear combination of RSSI (Received Signal Strength Indicator) and distance is proposed. The system model under study is a multi-hop network with two fixed access points, some moving terminal repeaters, and a mobile terminal. The mobile terminal moves from one access point to the other, and makes handoff thru the terminal repeaters to maintain access to service. Simulation is made and the results are compared against the RSSI-only algorithm and the distance-assisted algorithm [2]. It is found that the proposed algorithm achieves lower handoff percentage and outage occurrence.

In anycast routing the packet is routed to anyone of the anycast group members. Anycast allows supporting many services and can significantly improve network performance of wireless networks. In this paper, we provide an analysis of anycast routing in mobile ad hoc networks. We also show the correlation between mobility and the probability of connected route in anycast scenario and impact of the node degree density. To evaluate improvement of the network performance we design anycast proactive protocol with two modes. The first routing mode considers only the shortest path routing and another considers also the node degree density through the count of routes to the anycast group member. We also compare the performance with a potential field-based proactive anycast protocol.

本論文では直交周波数分割多重(OFDM:Orthogonal Frequency Division Multiplexing)システムに対して高速フェージング環境下においても高精度に動作できる逐次型チャネル推定(SCE:Sequential Channel Estimation)と適応同時最大事後確率(AJMAP:Adaptive Joint Maximum A Posterior Probability)を用いた単一アンテナ同一チャネル干渉除去方式を検討したので提案する.本論文で提案したSCE-AJMAPアルゴリズムは,シンボルごとに各基地局のチャネル応答を推定し,受信機側にあるジョイントトレリス生成出力をシンボルごとに更新することにより,高速フェージングによる希望信号と干渉信号が合成された受信信号の振幅変動をより精密に追従できる.本論文では計算器シミュレーションにより,提案したSCE-AJMAP復号器が従来のJMAP復号器に比べて高速フェージング環境における受信機の特性を大きく改善できることを確認した.

We study a cognitive channel reuse approach for autonomous femtocell deployment in an OFDMA-based cellular network. The objective is to manage the uplink interference from macrocell users to femtocell access points. Macrocell users are normally far away from the base station and may cause strong uplink interference to the close-by femtocells. By cognitive interference recognition, a femtocell access point autonomously reuse the proper channel modes for interference minimization. We propose an opportunistic channel scheduling scheme that determines optimal channel and power allocation to femtocell users. Simulation results show improved uplink performance in terms of the average channel outage probability in femtocells.

Mobile sensor networks have received significant attention recently. Mobile sensors are deployed to achieve network load balancing, prolonging network lifetime, and improving network coverage, by monitoring critical areas where manual sensor deployment cannot be performed. To achieve these goals, energy estimation is one of the main constraints and concerns to consider, while deploying mobile sensors in a sensor field. Most of the energy models designed for sensor networks assumed static sensors. In this paper, we propose a comprehensive energy model to estimate the overall energy consumption through power dissipation, for both static and mobile sensors in the potential sensor fields. We calculate the total remaining lifetime of mobile sensor networks from the total power dissipation. By predicting the remaining lifetime of any network in different network scenarios at a given instance of time, an optimum network strategy can be designed for a given application. © 2010 IEEE.

In orthogonal frequency division multiplexing (OFDM) based cellular systems, co-channel interference (CCI) would greatly degrade the bit error rate (BER) performance of cell-border users. Joint maximum likelihood sequence estimation (JMLSE) based single antenna interference cancellation (SAIC) algorithms have been under intense research. In this paper, both the upper and lower error probability bounds for JMLSE are extended to MQAM-OFDM systems based on a genie-aided receiver. The derived upper and lower bounds are valid for any MQAM and an arbitrary number of interferers. A tighter lower bound is derived by replacing the genie with a less generous one. We prove that this new lower bound is much tighter compared to the conventional lower bound.

Mobile Sensor Networks (MSN) are used for network load balancing, prolonging network lifetime, and improving network coverage by monitoring critical areas where manual sensor deployment cannot be performed. Addressing the problem of how to achieve maximum network coverage and network uniformity, after deploying sensors in critical areas randomly, is of significant importance recently. In this paper, we design an energy efficient distributed self-deployment algorithm, which is based on the diffusion of mobile sensors in the Region of Interest (ROI). Mobile sensors are diffused from denser sensors area to lesser or uncovered area in ROI, on the basis of localized information. Our algorithm considers ROI with the absence as well as presence of obstacles. Resemblance in the numerical and simulation analysis confirms the concreteness of our algorithm.

In orthogonal frequency division multiplexing (OFDM) based cellular systems, co-channel interference (CCI) from adjacent interfering base stations (BSs) would greatly degrade the bit error rate (BER) performance of cell-border users. In the previous work, a blind single antenna interference cancellation (SAIC) algorithm named least mean square-blind joint maximum likelihood sequence estimation (LMS-BJMLSE) has been proposed. The proposed LMS-BJMLSE algorithm is blind with respect to interfering signals and neither the training sequence (TS) nor pilot signal from interferers is needed. However, the conventional LMS-BJMLSE requires a long training sequence (TS) for channel estimation. In this paper, we propose a TS reduction scheme in which the subcarriers are divided into small groups based on the coherence bandwidth, and the slowest converging subcarrier in each group is identified by exploiting the correlation between the mean-square error (MSE) produced by LMS and the mean-square deviation (MSD) of the desired signal. The identified subcarrier's channel estimate is replaced by the interpolation result using the adjacent subcarriers' channel estimates. Simulation results demonstrate that the proposed algorithm could reduce the required TS length by 80%. ©2010 IEEE.

Mobile Sensor Networks (MSN) are used for network load balancing, prolonging network lifetime, and improving network coverage by monitoring critical areas where manual sensor deployment cannot be performed. Addressing the problem of how to achieve maximum network coverage and network uniformity, after deploying sensors in critical areas randomly, is of significant importance recently. In this paper, we design an energy efficient distributed self-deployment algorithm, which is based on the diffusion of mobile sensors in the Region of Interest (ROI). Mobile sensors are diffused from denser sensors area to lesser or uncovered area in ROI, on the basis of localized information. Our algorithm considers ROI with the absence as well as presence of obstacles. Resemblance in the numerical and simulation analysis confirms the concreteness of our algorithm. ©2010 IEEE.

近年,マルチキャリヤ変調方式は高効率データ伝送を実現することから,多くの無線システムに採用されている.一方,受信機の小型化のためには,中間周波数の処理がないダイレクトコンバージョン方式を用いることは重要である.しかし,マルチキャリヤ変調方式は,高速伝送化に伴いDFT(Discrete Fourier Transform)の次数を高めることでPAPR(Peak-to-Average Power Ratio)が大きくなるという問題点がある.このため,LTE(Long Term Evolution)では,下りリンクではOFDM(Orthogonal Frequency Division Multiplexing),上りリンクではSC-FDMA(Single Carrier Frequency Division Multiple Access)方式が採用されている.マルチキャリヤ伝送方式にダイレクトコンバージョン受信機を採用する場合,広帯域化による受信機内部の自己混合によりDCオフセットが発生し,受信感度の劣化が大きな問題となる.本論文では,ダイレクトコンバージョン受信機におけるOFDM,SC-FDMA変調方式の受信信号におけるDCオフセットひずみの軽減方法を提案し,伝送特性を計算機シミュレーションにより評価した結果,従来の単純な平均振幅によるDC除去方式と比較してシンボル誤り率を改善できることを示す.

近年,マルチキャリヤ変調方式は高効率データ伝送を実現することから,多くの無線システムに採用されている.一方,受信機の小型化のためには,中間周波数の処理がないダイレクトコンバージョン方式を用いることは重要である.しかし,マルチキャリヤ変調方式は,高速伝送化に伴いDFT(Discrete Fourier Transform)の次数を高めることでPAPR(Peak-to-Average Power Ratio)が大きくなるという問題点がある.このため,LTE(Long Term Evolution)では,下りリンクではOFDM(Orthogonal Frequency Division Multiplexing),上りリンクではSC-FDMA(Single Carrier Frequency Division Multiple Access)方式が採用されている.マルチキャリヤ伝送方式にダイレクトコンバージョン受信機を採用する場合,広帯域化による受信機内部の自己混合によりDCオフセットが発生し,受信感度の劣化が大きな問題となる.本論文では,ダイレクトコンバージョン受信機におけるOFDM,SC-FDMA変調方式の受信信号におけるDCオフセットひずみの軽減方法を提案し,伝送特性を計算機シミュレーションにより評価した結果,従来の単純な平均振幅によるDC除去方式と比較してシンボル誤り率を改善できることを示す.

For wireless multicast applications like multimedia conferencing. voice over IP and video/audio streaming, a reliable transmission of packets within short delivery delay is needed. Moreover, reliability is crucial to the performance of error intolerant applications like file transfer. distributed computing, chat and whiteboard sharing. Forward Error Correction (FEC) is frequently used in wireless multicast, to enhance Packet Error Rate (PER) performance, but cannot assure full reliability unless coupled with Automatic Repeat Request forming what is knows as Hybrid-ARQ. While reliable FEC can be deployed at different levels of the protocol stack, it cannot be deployed on the MAC layer of the unreliable IEEE802.11 WLAN due to its inability to exchange ACKs with multiple recipients. In this paper. we propose a Multicast MAC protocol that enhances WLAN reliability by using Adaptive FEC and study it's performance through mathematical analysis and simulation. Our results show that our protocol can deliver high reliability and throughput performance.

We study a method of cognitive interference management in user-deployed 3G femtocell networks. Each femtocell cognitively recognizes an interference signature from the network environment and opportunistically allocates the proper channel patterns for interference minimization. Simulation results show great channel SINR improvement by implementing our opportunistic channel scheduler. The approach offers a novel view of autonomous spectrum management based on cognitive interference recognition and adaptive channel management. ©2009 IEEE.

This paper describes the velocity adaptive vertical handoff algorithm on multi-frequency band wireless systems (V-MFVHO: Velocity adaptive Multi Frequency Vertical HandOff) in order to achieve the homogeneous handoff decision strategy. WiMAX Forum has published three licensed spectrum profiles: 2.3GHz, 2.5GHz and 3.5GHz. These frequency bands operated by WiMAX coexist on the same service area. In heterogeneous wireless networks, the problem is complicated since there are many differences cell coverage due to the frequency band, traffic conditions, data rate, and moving speed of MS (Mobile Station). This paper clarifies the design a scheme for selecting the candidate cells to satisfy the QoS requirements from each MS using the estimation of the location and the velocity of each MS by back-propagation neural network and the traffic and RSSI (Received Signal Strength Indicator) conditions of MS for each cell allocated for different frequency bands.

In orthogonal frequency division multiplexing (OFDM) based cellular systems, co-channel interference (CCI) from adjacent interfering base stations (BSs) operating and co-existing with the desired BS in the same frequency channel would greatly degrade the bit error rate (BER) performance of mobile receivers which are near to cell borders. CCI cancellation algorithms by using only one receiving antenna named single antenna interference cancellation (SAIC) have been under intense research. However, most of these algorithms require additional information from interfering signals. Furthermore, the orthogonality of a asynchronous interfering signal is destroyed and therefore, conventional SAIC algorithms cannot be applied. In this paper, we propose a blind SAIC algorithm named least mean square-blind joint maximum likelihood sequence estimation (LMS-BJMLSE) for asynchronous interference cancellation. The proposed LMS-BJMLSE algorithm is blind with respect to interfering signals and neither the training sequence (TS) nor pilot signal from interfering signals is needed. Its complexity is independent of channel length compared to the conventional time domain JMLSE algorithm. Simulation results show that the proposed LMS-BJMLSE algorithm could greatly improve the BER performance in both synchronous and asynchronous interference conditions.

In anycast routing the packet is routed to anyone of the anycast group members. Anycast allows supporting many services and can significantly improve network performance of ad hoc networks. Unicast protocols have been extended to support anycast routing, however, these protocols consider solely the shortest path routing. The protocols based on a theory of potential fields have been proposed to improve packet delivery ratio in large mesh networks by routing to area with higher density of nodes instead of the shortest path routing. In this paper, we consider the density of nodes through count of routes. We propose simple anycast protocol which utilizes count of routes to the anycast group member as a routing metric and evaluate its performance.

Routing in Ad-hoc networks is unreliable due to the mobility of the nodes. Location-based routing protocols, unlike other protocols which rely on flooding, excel in network scalability. Furthermore, new location-based routing protocols, like, e.g. BLR [1], IGF [2], & CBF [3] have been proposed, with the feature of not requiring beacons in MAG layer, which improve more in terms of scalability. Such beaconless routing protocols can work efficiently in dense network areas. However, these protocols' algorithms have no ability to avoid from routing into sparse areas. In this article, historical signal strength has been added as a factor into the BLR algorithm, which avoids routing into sparse area, and consequently improves the global routing efficiency.

Mobile sensor networks have received significant attention recently. Mobile sensors are deployed to achieve network load balancing, prolonging network lifetime, and improving network coverage, by monitoring critical areas where manual sensor deployment cannot be performed. To achieve these goals, energy estimation is one of the main constraints and concerns to consider, while deploying mobile sensors in a sensor field. Most of the energy models designed for sensor networks assumed static sensors. In this paper, we propose a comprehensive energy model to estimate the overall energy consumption through power dissipation, for both static and mobile sensors in the potential sensor fields. We calculate the total remaining lifetime of mobile sensor networks from the total power dissipation. By predicting the remaining lifetime of any network in different network scenarios at a given instance of time, an optimum network strategy can be designed for a given application.

For end-to-end wireless multicast applications like multimedia conferencing, voice over IP and video/audio streaming applications which require reliable transmission of frames within short delivery delay, adding MAC layer H-ARQ (Hybrid Automatic Repeat Request) can enhance reliability and delivery delay. However, IEEE802.11 does not support reliable multicast due to its inability to exchange ACKs with multiple recipients. In this paper, we propose a protocol that enhances WLAN reliability performances by using Adaptive FEC (Forward Error Correction) while maintaining an optimal throughput performance.

IEEE802.11b standard provides 1, 2, 5.5, 11 Mbps data rates. These data rates can be made possible by using different modulation techniques: DBPSK, DQPSK, CCK5.5 and CCK11 respectively. Rate adaptation is the process of dynamically selecting a proper modulation scheme depending on channel conditions in order to improve total throughput. Current rate adaptation protocols deal with unicast links rather than multicast. Measuring the received Signal Strength (RSS) of a feedback message (CTS, ACK) to estimate the receiver's link condition, can be one way to do this. A receiver may send its channel condition information to the sender allowing it to adapt its data rate for the following transmission. IEEE802.11 standard however, does not provide feedback messages for MAC layer recovery on multicast frames. This is due to collisions occurring if multicast group members simultaneously initiate a feedback message. Therefore, in order to link adapt multicast, a reliable multicast MAC protocol has to be introduced. In this paper, we propose a Rate Adaptive Multicast (RAM) protocol which provides reliability to WLANS and enhances its throughput by using Rate Adaptation. Further, we evaluate our protocol by throughput analysis and computer simulation. Simulation results suggest that our protocol performs better than related/existing protocols in both throughput as well as reliability.

IEEE802.11b standard provides 1, 2, 5.5, 11 Mbps data rates. These data rates can be made possible by using different modulation techniques: DBPSK, DQPSK, CCK5.5 and CCK11 respectively. Rate adaptation is the process of dynamically selecting a proper modulation scheme depending on channel conditions in order to improve total throughput. Current rate adaptation protocols deal with unicast links rather than multicast. Channel conditions can be estimated by measuring the Received Signal Strength (RSS) of a feedback message (CTS, ACK). However, IEEE802.11 standard does not provide feedback messages for MAC layer recovery on multicast frames. This is due to collisions which may occur to simultaneous feedback messages from multicast group members. Therefore, in order to rate adapt multicast, a reliable multicast MAC protocol has to be introduced. In this paper, we propose a protocol which provides multicast reliability to WLANs and enhances its throughput by using rate adaptation. Further, we evaluate our protocol by throughput analysis and computer simulation. Simulation results suggest that our protocol performs better than a related/existing protocol in both throughput as well as reliability performances.

In this paper, a sub-optimal Rake receiver combined with a Wiener Filter is investigated for use in an indoor environment. InnerChip-interference is dominant when the application is indoors, so the innerchip-interference rejection function becomes critical for the receiver. Pilot symbols in each slot are used for channel estimation and weight calculation of Rake combining through Wiener Filter. Compared to conventional combining which uses maximum ratio combining, Wiener combining using IRC (Interference rejection combining) achieves better ICI (Inner-chipInterference) rejection. This paper clarified that the sub optimal Rake receiver using Wiener Filter is 4 dB better than the conventional Rake receiver under the indoor application.

This paper proposes a new SSB-QPSK modulation/demodulation method. The present method multiplexes the USB (Upper Side Band) and LSB (Lower Side Band) of a QPSK-modulated SSB (Single Side Band) on the same SSB complex frequency band. The present method thus achieves 2 bit/s/Hz. This method is an orthogonal SSB-QPSK method, because the multiplex signals are orthogonal to each other. The demodulator consists of two SSB demodulators. A simulation result in AWGN conditions, shows that the proposed method has better BER (Bit Error Rate) performance than 16 QAM. The degradation of BER in comparison with QPSK is less than 0.2 dB on Eb/No (bit-energy-to-noise-power ratio). In a fading/Doppler environment, the BER performance of the orthogonal SSB-QPSK is the same as that of QPSK.

The performance of a proposed handoff algorithm based on both the distance of a mobile station to neighboring base stations and the relative signal strength measurements is evaluated. The algorithm performs handoff when the measured distance from the serving base station exceeds that from the candidate base station by a given threshold and if the measured signal strength of the adjacent base station exceeds that of the serving base station by a given hysteresis level. The average handoff delay and average number of handoffs are used as criteria for performance. Numerical results are presented to demonstrate the feasibility of the distance-based handoff algorithm, including results for an additional criterion based on relative signal strength. The proposed algorithm is compared with an algorithm based on absolute and relative signal strength measurements and with a solely distance-based algorithm. It is found that the proposed handoff algorithm performs well in a log-normal fading environment when the distance estimate error is modeled by wide-sense stationary additive white Gaussian noise.

This paper assesses the performance of the handoff algorithm based on distance and RSSI measurements in a multi-cellular environment by computer simulation. The algorithm performs a handoff if handoff initiation conditions, handoff possible conditions, and handoff selective conditions are met. The performance criteria are based on the average number of handoffs, the crossover points and the average number of outages. Numerical results are presented to demonstrate the feasibility of the algorithm. The performance of the distance-assisted handoff algorithm is compared with that of a conventional algorithm that utilizes signal strength alone. Overall, the distance-assisted algorithm exhibits higher performance in average number of handoffs and the crossover points, yet exhibits a higher number of outages on average than the conventional algorithm.

In this paper, the performance of a higher data rater OFDM system based on IEEE802.11a is described. The performance of the OFDM system which is applied 256QAM and 1024QAM to obtain higher data rate than 64QAM, are evaluated in A WGN and multi path fading environment. Also the system with ADC performance and required SNR are given. This shows 1024QAM OFDM system has capability of an candidate of the higher data rate wireless LAN system, target to 100Mbps.

In this paper,a simplified and sub-optimal wideband CDM4 downlink rake receiver with Wiener combining is investigated. Pilot symbols in each of slots will be used for channel delay estimation and weight calculation. Compared to conventional combining which uses MRC(maximum ratio combining), Wiener combining which uses IRC (Interference rejection combining) can get better MAI (Multiple Access Interference) rejection. For AWGN channel and Clarke's Rayleigh Fading channel with four performance of the independent paths, We simulate the BER per rake receiver with Wiener filter. From the simulation result, although we get about 1.5dB performance degraded in AWGN and 6 to 7 dB degraded in Rayleigh Fading channel as compared to the ideal performance, its simplified algorithm can be an advantage of implementation.

We analyzed the handoff performance of a multihop-based wireless LAN that uses Access Points (APs) for communication. When a mobile terminal isn't able to communicate with any APs, it uses other mobile terminals as Terminal Repeaters (TRs). The handoff criteria are based on absolute and relative signal strengths. The performance criteria are the average number of handoffis and the average handoff delay. We investigated the relation between the handoff criteria and the performance criteria when both the mobile terminal and the terminal repeaters are moving. Numerical results are presented to show that the average handoff delay decreases but the average number of handoffis increases as the TRs' moving speed is increased.

任意の電波を発射する電波源の位置を双曲線法を用いて推定する.双曲線法における位置測定精度は各センサ間の距離差検出精度に依存する.距離差は電波の伝搬遅延時間差に光速を乗じることにより得られるため, 高精度な時間差検出が必須である.本論文では, 従来時間軸上で直接行っていたセンサ局間の伝搬遅延時間差検出を周波数軸上で行った.周波数上に展開した各周波数成分の位相を検出し, 位相差を各成分の受信電力に応じて合成した後に時間差に換算することにより, 高精度な時間差推定が可能となる.シミュレーションの結果, マルチパスフェージング伝搬環境, 未知局信号のベースバンド帯域幅±3kHz, S/N10dBにおいて, 80〜260mの位置測定精度が得られることを明らかにした.

Burst synchronization scheme for millimeter band OFDM uplink system is proposed. For the estimation of subscribers access and its frequency offset and time offset, OFDM-CDMA pilot signal is adopted. The accuracy and probability of error estimation are investigated by the theoretical analysis and simulations. This paper clarified that the proposed synchronization scheme has the capacity of four users simultaneous access with 10% of error estimation probability, when 64 of the number of subchannels are used for spreading each subscribers pilot signal.

This paper describes a forward subchannel control of multi-carrier scheme intended to compensate for phase/amplitude distortions under frequency selective fading. The forward subchannel control scheme is used for a Time Division Duplex (TDD) multi-carrier system on up-link. The forward subchannel control scheme provides forward subchannel control of phase/amplitude variation and subchannel assignment control. These controls are applied before transmission of an up-link signal. The forward control parameters are estimated by a preamble down-link signal. Simulation results clarify that the BER performance with the forward subchannel control scheme shows a superiority of more than one order at the condition of 22 dB of E-b/N-o and 400 Hz of fading frequency.

This papa describes an equalization scheme of an inner chip distortion which is awed by multi-path fading on a multi-carrier CDMA system. The proposed equalization scheme uses Auto-regressive Process model (AR) and prediction parameters of AR are obtained by Recursive Last Square algorithm (RLS). Simulation results of the multi-carrier CDMA system using the inner chip equalizer clarified that BER is 1.1x10(-2) at 20 dB of Eb/NO under the condition of two multi-path fading environments of which delay time is 2 mu sec and 100 Hz Of fading frequency. In the evaluation of system parameters of the multi-carrier CDMA, number of subchannels are 16, data rate is 32 kbps and spreading ratio is 16.

This paper describes the Bit Error Rate (B.E.R) performance of the mult-carrier CDMA modulation under the frequency selective fading. The multi-carrier CDMA signal is obtained by spreading the multicarrier signal using the peculiar PN (Pseudo Random) code. The received multi-carrier CDMA signal is correlated and demodulated by the rake receiver. The output signal of the rake receiver is converted to subchannel signals through the discrete fourier transform (dft) and the received data is detected through S/P (Serial Parallel converter). This paper clarifies that BER performance of the multi-carrier CDMA becomes 10(-3) under the condition of two multipath condition and 100 Hz of the fading frequency.

This paper describes two dimensional (2D) equalization scheme of orthogonal coding multi-carrier CDMA for reverse link of mobile communication systems. The purpose of the 2D equalization is the reduction of Multiple Access Interference (MAI) which is caused by the random access and the different propagation path from each mobile station. The orthogonal coding multi-carrier CDMA multiplexes all mobile stations' data by Code Division Multiplexing (CDM). The 2D coding scheme spreads a preamble signal at time (in subchannel signals) and frequency (between subchannel signals) domains. The 2D decoding scheme estimates transmission delay time and instantaneous fading frequency from preamble signal for individual mobile stations and compensate the received data using these estimation values to reduce MAI.

This paper describes a delay control scheme for synchronous detection of an orthogonal coding multi-carrier CDMA (Code Division Multiple Access) system. The delay control scheme estimates transmission timing of data from each mobile station. At a base station. delay time is obtained by detecting phase shift value of the preamble signal from each mobile station. The estimated transmission timing information is sent from base station to each mobile station and the mobile station then adjusts its transmission timing. Simulation results clarified that Bit Error Rate (BER) is 2.5 x 10(-3) at 19 dB of E-b/N-0 under conditions of 29.4 msec initial delay time, 32 kbit/sec data rate, 16 subchannels and 100 Hz of fading frequency.

T1P1 J-STD-015 (TIA IS-665) is a 1.9 GHz wideband CDMA personal communications system which was standardized in the U.S.A. during 1995. At present, the W-CDMA maximum data rate is specified at 64 kbps which allows G4 facsimile transmission. W-CDMA is a candidate for wireless local loop (WLL) applications. The WLL requires ISDN compatibility at the air interface. This paper describes an improvement to the W-CDMA data transmission system which provides full 2B+D ISDN (Integrated Services Digital Network) capability.

This paper clarifies an estimation method of a carrier offset frequency of an orthogonal coding multi-carrier CDMA system under a multi-path fading. This paper analyzes an inter channel interference and an inner channel interference which are caused by the multicarrier offset frequency. An estimation method of the carrier offset frequency adopts a prediction method. Prediction coefficients are obtained by Burg algorithm of a Maximum entropy method. As a result of a simulation, it shows that Bit Error Rate (BER) is 3.5x10(-2) at 15 dB of E-6/N-0 for 32 kbit/sec of data rate and 16 subchannels of the orthogonal coding multi-carrier CDMA under a multi-path fading environment.

Group 3 error-free facsimile terminal for use in an analog cellular network has been developed. This facsimile terminal is provided with the International Telecommunication Union (ITU-T, formerly CCITT) T.30 recommendation protocol and an adaptive error control scheme (AECS) for Group 3 communication and error-free communication. The AECS monitors the channel conditions and selects the optimum error correction code. ITU-T V.27ter is used as the modulation method and the transmission rate is 4800 bps. This system is compatible with the modified Huffman (MH), modified READ (MR), and modified modified READ (MMR) image data compression codes. The average communication time of this facsimile terminal is 40 s per page under moving condition through the analog cellular network. © 1996 IEEE.

In implementing the future Personal Communication Services (PCS), providing a system allowing simultaneous access by many subscribers is of utmost importance. The study of CDMA, as a candidate for the radio access method is being promoted for this purpose. Increasing the CDMA system capacity is determined by; the selection of a spread code having an excellent correlation characteristic [1]; the interference cancellation method [2], [3], and; the method for controlling the power accordance with the near-far problems [4]. In this paper we considered the cellular system, and have analyzed the correlation characteristic by using the PN or Walsh code as the innercell spreading code and the PN or Gold code as the intercell spreading code. We have also analyzed the system capacity in terms of the correlation characteristics for different combinations of these spreading codes. It has been clarified as a result that 40 subscriber channels can be accommodated per cell by using the Walsh code and PN code as the innercell and intercell codes for the forward link (the Base Station (BS) to the Personal Station (PS)) and the PN code as both the innercell and intercell codes for the reverse link (the PS to the BS).

We presented a definition of a burst error channel using a Markov model in a previous paper [1]. This paper described a throughput analysis method of a hybrid automatic repeat request (ARQ) under the burst error channel using the three-state Markov model. The hybrid ARQ was studied for the random and burst error correction codes as the forward error correction (FEC) code, and multiframe rejection (MREJ) as the ARQ. The throughput efficiency was obtained with both an infinite buffer memory and a finite buffer memory. The applicable range of the burst error channel has been clarified for the hybrid ARQ using random and burst error correction codes. © 1993 IEEE

This paper describes a perspective on Personal Communications Services (PCS) and technological trends. It takes into consideration rules pertaining to the use of PCS for mobile radio communication and countermeasures to cope with the huge increase in PCS subscribers. In this paper, PCS network structures, inter-regional roaming, microcell structure, radio access and channel access methods are also covered as PCS technologies. Furthermore, trends in domestic and international standards are also described. Although these technologies present many difficulties, we believe that they will be overcome and PCS services will be introduced in the near future.

A high-speed and error-free voiceband data communication method using a hybrid automatic repeat request (ARQ) protocol over an analog cellular system is described. The present method adopts an adaptive error control scheme (AECS). This error control scheme automatically selects the optimal error correction code according to circuit bit error rate (BER), so as to match it to the frequently changing mobile radio propagation paths (MRPP) conditions. This method adopts multiframe rejection (MREJ) as a retransmission scheme for a high throughput efficiency on the burst error circuit. Actual field evaluation was made by mounting this protocol on a CCITT V.22bis modem with a data transmission speed of 2400 b/s and a modulation method using 16 carrier states over the Advanced Mobile Phone Service (AMPS) in Atlanta, GA, verifying that data communication can be achieved with an average throughput efficiency of 70% over a radio channel having a BER up to 10(-2).

This paper describes the evaluation results for Group 3 (G3) facsimile transmission in the transparent mode over the digital cellular system. Effectiveness of a convolutional code is clarified for encoding the G3 facsimile data from analysis of error correction capability for the transparent mode. The 1/2 convolutional code is used as the error correction code in the digital cellular circuit, and a simulation experiment is conducted at the data transmission speed of 4,800 bit/sec in a G3 facsimile. It has been clarified that the transparent transmission system is applicable up to a fading frequency of 80 Hz, a received power of -100 dBm and a handoff occupancy frequency of 4 times per minute on asumption of handoff occurrence probability in a Poisson distribution. This scheme presents the high reliable G3 facsimile transmission which does not depend on delay time of the digital cellular system.

To realize high speed data communication in a cellular system, the characteristics of mobile radio propagation paths (MRPP), and a robust error control scheme for poor circuit quality must be studied. This paper discusses the following: 1) MRPP are analyzed by computer simulation, and an analysis method is described that used a Markov model for burst errors generated by the simulation. 2) By simulating the locus of moving vehicles, the relationship between the carrier-to-noise ratio (CNR), the fading frequency of a moving vehicle and the three-states Markov model is shown. 3) An adaptive error control scheme (AECS) is constituted as an effective high speed data communication scheme in an analog cellular system. The effectiveness of the AECS is analyzed by simulating its application rate, using the three-states Markov model. 4) An in a subcarrier transmission system with a 4800 b/s data transmission rate, using the three-states Markov model. 4) An assessment using actual field data in the U.S. and the U.K. is also performed, and the analysis method is verified and the characteristics of the AECS are evaluated using the data.