In this paper, a novel triple-band antenna with reflector surface which has the property of both artificial magnetic conductor (AMC) surface and perfect electric conductor (PEC) for WLAN and Sub-6G 5G applications is proposed. The presented antenna is composed of two parts: the AMC surface and the microstrip-fed printed dipole. Baluns are used to excite the dipoles. This antenna design combines the advantages of AMC and PEC. In lower band and middle band, the inserted board works as AMC surface. This AMC surface can help the antenna to achieve unidirectional radiation pattern and low-profile characteristics. While at upper band the antenna works as PEC surface. PEC surface increases the gain of the antenna in upper band. As a result, the proposed antenna can offer an impedance band from 2.39 GHz to 2.63 GHz and from 3.61 GHz to 3.72 GHz and from 5.61 GHz to 5.84 GHz when the S11 is less than - 10dB. Stable radiation patterns with peak gain of 5.6 dBi, 6.5 dBi and 9.6 dBi are obtained in lower band, middle band and upper band, respectively. The proposed antenna can be used for multiband base stations for WLAN and 5G applications.

This article proposes a novel chunk-based caching scheme known as the Progressive Popularity-Aware Caching Scheme (PPCS) to improve content availability and eliminate the cache redundancy issue of Information-Centric Networking (ICN). Particularly, the proposal considers both entire-object caching and partial-progressive caching for popular and non-popular content objects, respectively. In the case that the content is not popular enough, PPCS first caches initial chunks of the content at the edge node and then progressively continues caching subsequent chunks at upstream Content Nodes (CNs) along the delivery path over time, according to the content popularity and each CN position. Therefore, PPCS efficiently avoids wasting cache space for storing on-path content duplicates and improves cache diversity by allowing no more than one replica of a specified content to be cached. To enable a complete ICN caching solution for communication networks, we also propose an autonomous replacement policy to optimize the cache utilization by maximizing the utility of each CN from caching content items. By simulation, we show that PPCS, utilizing edge-computing for the joint optimization of caching decision and replacement policies, considerably outperforms relevant existing ICN caching strategies in terms of latency (number of hops), cache redundancy, and content availability (hit rate), especially when the CN's cache size is small.

This paper explores a cooperative partnership and data forwarding model in wireless sensor networks using unmanned aerial vehicle (UAV) with the goal of enhancing the data collection efforts. A UAV-based data acquisition architecture is presented to suppress the limitations of the traditional wireless sensor network. For this, we introduce a flexible and fast approach to collect data by taking into consideration the mobility of the mobile sink (UAV) and sensor nodes in the network. In other words, leveraging the mobility of the UAV and the location of sensor nodes, we adopt a novel frame selection technique that classifies sensor nodes into different frames. Then we present a cooperative partnership model that allows sensor nodes in the network to individually pair with their peers and thus transmitting data simultaneously. We also aim to alleviate the packet loss originated from certain sensor nodes located in the rear edge-side of the UAV's coverage area. This situation happens when the UAV is moving in the forward direction while collecting data. Thus, to alleviate these packet losses while guaranteeing a higher success rate of packet reception ratio, we propose a novel data forwarding scheme to closely integrate with the aforementioned partnership model. We conduct simulations to verify our proposed framework, and results show huge performance gain is obtained over the traditional data collection technique.

This paper proposes a novel data acquisition framework in sensor networks using an unmanned aerial vehicle (UAV) with the goal of increasing the efficiency of the data gathering efforts. To maximize the system throughput, we introduce a priority-based frame selection scheme to suppress the number of redundant data transmissions between sensor nodes and the UAV. Toward this goal, we classify the nodes inside the UAV's coverage area into different frames according to their locations. Taking advantage of the mobility of the UAV, we assign different transmission priorities to nodes in different frames. To do that, we introduce an adjustment to the contention window value used in IEEE 802.11 MAC, thereby defining a lower contention window range to the frame with higher priority ( urgent area) and a higher contention window range to the frame with lower priority ( less important area). The proposed framework leads to a reduction in packet collisions and, at the same time, minimizes the packet loss originated from nodes in the rear-side of the UAV when the UAV moves in the forward direction. To optimize the networks' energy consumption, we present a novel routing protocol based on the aforementioned framework. By leveraging the proposed framework and routing algorithm, we aim to reduce the transmission distances between senders and receivers. A shorter distance leads to better channel quality and energy savings, as is verified by our simulation studies and results.

This paper presents a novel ticket gate system employing optical wireless communication used at a train station in Japan. The proposed system needs two optical wireless card readers attached to two inner sides of the gate. According to our study, we found that the proposed system has higher received power compared to the conventional train ticket gate system. It also has higher probability of success as long as the communication distance is less than 0.28 meters. As a result, the proposed system has a better performance compared to the conventional one and its availability is guaranteed.

Satellite clusters have been satisfactorily implemented in a number of applications, such as positioning and sensor networks, with the purpose of improving communication system capabilities. However, because the use of clusters requires good management of the resources, those solutions imply new challenges for communication systems. This paper focuses on improving the data management between network elements by considering a network formed by satellite clusters. Satellite clusters work in cooperation to provide real-time and non-real-time services in different footprint areas. This study proposes the adjustable energy consumption access scheme (AECS) as one possible solution response to particular necessities of communication and at the same time, as a way of decreasing the system energy consumption. Energy consumption is a key issue that concerns green network operations and it is directly linked to the cooperation and coordination between network elements. On the other hand, we support the implementation of Optical Inter-Satellite Links (OISL) for communication between cluster elements. The analysis involves the study of energy consumption, transmission delay, specific link margins, bit error rate (BER) and QoS.

多数のセンサやアクチュエータを接続したサーバ集中型の M2M システムのフィードバック制御では,制御遅延および制御競合の課題がある.本稿では,これらの問題を解決するためのルールベース自律制御方式を提案する.提案方式は,トリガとアクションから構成される制御ルールに基づいて,M2M ゲートウェイが自律的にアクチュエータを制御することにより,制御遅延および制御競合を回避する.また,本方式を採用することにより,サーバを経由せずに M2M ゲートウェイ間を自律的に連携させることができる.本稿では,提案方式に基づく自律分散協調 M2M システムのプロトタイプを構築して,その動作検証を行うことにより,その有効性を示す.

サーバ集中型の大規模な M2M システムにおけるデータ収集は,ネットワーク負荷やデータ蓄積コストの増大という課題がある.また,複数の異なるアプリケーションが同一のセンサからデータ収集を行う場合,競合が発生する.本稿では,これらの問題を解決するためのイベント駆動データ収集方式を提案する.提案方式は,M2M ゲートウェイにおいて,閾値,外れ値および変化率の変化をイベントとして,必要最小限のデータを M2M サーバに送信する.また,複数のデータ収集の条件を統合することにより,データ収集の競合を回避する.本研究では,提案方式に基づく自律分散協調 M2M システムのプロトタイプを構築し,提案方式の有効性についての評価を行った.

This paper proposes the Piggyback schemes between each User Equipment (UE) in cellular networks. This scheme is able to reduce a communication traffic volume of base station by each UE cooperates with other one. Therefore, it can make a smaller load in base station. Each UE establishes an independent connection and communication in current mobile network. When a UE accesses a base station, the UE receive data from other UEs nearby by device-to-device communication and the UE sends its own uplink data with the received data in this proposed method. We name the method a "Piggyback scheme". Here we introduce two methods; one is "real-time active calling based piggyback scheme". The calling UE receives uplink data from other UEs and the UE sends the data in free white space of its own real-time active call channel while using call function in this scheme. The second one is "Data aggregation piggyback scheme". In this scheme, when the UE sends its own uplink data to base station, the UE informs that it can piggyback execute for nearby UEs, and the UE receives data from the nearby UEs. And the UE sends data that includes its own and other's data. And piggyback request UEs use broadcast scheme in searching piggyback execution UE and it choice the best condition piggyback execution UE every time with plural evaluation criteria. In this paper, we confirm that performances of the proposed schemes have an effect on the load reduction of cellular network as it has been shown in the simulations.

Satellite clusters have been satisfactorily implemented in a number of applications, such as positioning and sensor networks, with the purpose of improving communication system capabilities. However, because the use of clusters requires good management of the resources, those solutions imply new challenges for communication systems. This paper focuses on improving the data management between network elements by considering a network formed by satellite clusters. Satellite clusters work in cooperation to provide real-time and non-real-time services in different footprint areas. This study proposes the adjustable energy consumption access scheme (AECS) as one possible solution response to particular necessities of communication and at the same time, as a way of decreasing the system energy consumption. Energy consumption is a key issue that concerns green network operations and it is directly linked to the cooperation and coordination between network elements. On the other hand, we support the implementation of Optical Inter-Satellite Links (OISL) for communication between cluster elements. The analysis involves the study of energy consumption, transmission delay, specific link margins, bit error rate (BER) and QoS.

In this paper, a visible light communications (VLC) system prototype using organic light emitting diode (OLED) with dimming support was realized and tested. Frequency response and driving range of OLED were measured and discussed. Considering practical applications of OLED, variable pulse position modulation (VPPM) signal was used to support data transmission under dimming condition. Our prototype was able to transmit up to 85 kbps data rate using an OLED with only 7 kHz 3 dB modulation bandwidth. For the target BER = 10(-3) with FEC, the luminous flux could be varied within 5-8 lm.

In this paper, a visible light communications (VLC) system prototype using OLED was realized and tested. Using simple DPPM technique and comparator, our prototype was able to transmit up to 127.5 kbps data rate using an OLED with only 7 kHz 3 dB modulation bandwidth. Exploiting the frequency response of OLED, we were able to achieve a better data rate to modulation bandwidth ratio than other recent reports using OLED for VLC.

異質ネットワークにおけるエネルギー最適化は、消費電力とキャパシティとの間のバランスを取ることができる緊急のトピックである。本論文では、スリープモードを用いたセルサイズに基づくマクロ-フェムト二層ネットワークにおける電力消費に敏感なハンドオフ手法を提案する。提案手法は、拡張可能な室内フェムトアクセスポイント(FAP)、またはアクティブマクロ基地局(MBS)へ動的な確率で接続に、ユーザ端末(MUE)のハンドオーバを動的スケジューリングすることによって、モバイルユーザ端末の消費電力の削減と共にハンドオフの高安定性を実現することを狙いとする。無線指紋に基づいて位置測定を用いる、柔軟に変更できるマッチング領域付きエネルギー効率なスモールセル検知手法を提供する。FAP感知のために、MUE送信電力はトラフィックの負荷と位置関連性を参考にして適応的に調節されることができる。その上、トレードオフと共に総合的に評価し、提案したハンドオフ手法はマクロ-フェムト二層シナリオにおいてエネルギー効率化かつQoSの実現にポジティブな影響があることを示す。

In this paper, we propose an optical wireless communication service for indoor environment. To seamlessly cover the target area and keep the received signal power strength at an acceptable level, we send the signal from multiple diffused optical emitters and achieve possible transmit diversity. With the proposed diversity scheme, the effective coverage range of the proposed system can be significantly enlarged with a guaranteed BER performance. Simulation results show a 13.4 m(2) area can be effectively covered by two optical emitters with optical emitter spacing of 3 m and average transmit optical power of 28 dBm.

IEEE 1451 standard has been proposed to provide a common communication interface and transducer electric data sheet format for wired and wireless distributed applications in smart transducers (sensors and actuators). Currently, a unified Web service for IEEE 1451 smart transducers is a must. However, ensuring the security of web-services-based communications for IEEE 1451 smart transducers is an unsolved problem. In this paper, we proposed a cross-layer security mechanism that deals with the requirements of authentication, integrity, confidentiality, and availability across the communication process in IEEE 1451 smart transducers. The scheme contains three cross-layer components logically, including XML Encryption and Signature, SOAP Security Extension, and Web Services Description Language (WSDL) Security Checking. The former two components satisfy the requirements of confidentiality, availability, integrity, authentication, nonrepudiation, and freshness. The third component satisfies the requirement of availability, which can protect the system against denial-of-service (DoS) attack. The three cross-layer security components are integrated seamlessly in our scheme. To evaluate the overhead, we perform tests to evaluate the effect of message size on the performance of the access inquiry web service. The result supports the usefulness and feasibility of our scheme. © 2013 Jun Wu et al.

We present a study on evaluating the effects of multipath dispersion on indoor optical code division multiple access (CDMA) systems over optical wireless communication. The indoor propagation channel model which takes multiple reflecting surfaces into account is addressed. Theoretical analysis of the pulse response of direct light and reflected light is given. The bit error rate (BER) of this system is analyzed considering reflected light, background light, avalanche photo-diode noise, thermal noise, and multi-user interference. The results prove that the BER of the system is influenced by reflected light and that the effect of reflected light is related to room size and receiver position. With an increase in the number of users, the effect of reflected light becomes stronger and is a significant source of inter-symbol interference. It becomes clear that when optical CDMA is used in an indoor optical wireless system, the effect of reflected light is a key issue to be considered.

Developments in outdoor free space optical (FSO) communication between buildings using rooftop-mounted units are limited by Point-to-Point wireless links. We propose a space and time division multiple access scheme to perform Point-to-Multi-Point communication employing reflectors. A single reflector controlled by a stepping motor and an array of fixed reflectors are used. The reflection characteristics of the reflector are measured. The relationship characteristics between the static angle error of the stepping motor, the beam fluctuation, and the communication distance are demonstrated. The received optical powers are compared on using one or two reflectors while considering the angle of incidence at the surface of the reflector. Moreover, the received power, the bit error rate and the throughput of the experiment system are measured. In addition, the throughput characteristics of the proposal scheme are made clear by experiments. The result of the experiment shows that the new scheme can provide a low-cost and efficient method for Point-to-Multi-Point FSO communication(1).

We propose a position-based diversity transmission scheme for indoor optical wireless communication. In our scheme, the I (in-phase) and Q (Quadrature) signal of QPSK (quaternary phase-shift keying) modulation are transmitted separately to obtain a secure position-based transmission. We analyze probability of error with different mode numbers of the radiation lobe of Lambertian source, and position of the transmitters to attain single or multiple secure area(s). To obtain different secured areas, TDMA (time-division multiple access) with adaptive transmitted power for each time slot is applied. According to analytical results, the signal can be demodulated correctly only in the specific area and high-level security for optical wireless communication systems can then be achieved. In our scheme, the probability that the intruders can get the correct signal is decreased 90%, compared to conventional QPSK.(1)

This is a study on the effect of reflected light on optical code-division multiple-access (CDMA) system over indoor optical wireless communication (OWC). The indoor propagation channel model which takes multiple reflecting surfaces into account was addressed. Theoretical analysis of the pulse response of direct light and reflected light is given. Bit error rate (BER) of this system is analyzed considering reflected light, background light, avalanche photo-diode (APD) noise, thermal noise, and multi-user interference. The results prove that the BER of the system is influenced by the reflected light and the effect of reflected light is related to the room size and receiver position. With the increase of user number, the effect of reflected light becomes stronger and it is a significant source of inter-symbol interference. It becomes clear that when OCDMA is used to an indoor optical wireless system, the effect of reflected light is a key issue to be considered.

This paper presents a wireless relay scheme for indoor healthcare communication system, in which an optical relay link, instead of a traditional Radio Frequency (RF) relay link, is established between the relay station (RS) and the mobile terminal (MT). To simplify the structures of RS and the additional optical parts that shall be installed in the MT, the subcarrier-modulation based intensity-modulated direct-detection (IM/DD) is also adopted for both the up-link and the down-link. The proposed relay scheme not only enhances the transmission power, but also creates safe signal propagation environment, which is much meaningful for wireless and pervasive healthcare communication. Simulation results show that the proposed interference-reduced relay scheme provides a stable and high quality communication link when the average optical receiving power is larger than -25dBm.

This paper presents an optical intensity-modulated direct-detection (IM/DD) based relay scheme for indoor optical wireless communication system. Multiple distributed optical relay links are set up between relay stations (RS) and mobile terminals (MT) to create multiple safe signal propagation links for wireless communication so that at least one link is available for data streaming. Different from conventional relay scheme, the phase shift of RF signals is pre-adjusted based on maximum ratio transmission (MRT) technique, and then relayed from multiple distributed optical transmitters which are set up in different places. The proposed relay scheme not only enhances signal power and achieves diversity, but also avoids possible obstruction of line-of-sight (LOS) signal. Furthermore since propagation phase variation of incoherent optical signal can be neglected, the propagation space becomes a non-directional scalar space, resulting in a much simpler system structure, where multiple optical antenna elements can be freely arranged, phase shift due to different transmitting paths is solely decided by the distance between transmitter and receiver, etc. The paper presents these features and also provides computer simulation results to demonstrate the performance. Simulation results show that the proposed relay system is much feasible and attractive, and it would be one of the promising candidates for future wireless and pervasive healthcare communication systems.

There has been many developments in long distance optical wireless communication between buildings using rooftop-mounted units over Point-to-Point wireless links. We propose an Angle Division/Time Division Multiple Access scheme to perform Point-to-Multi-Point communication employing reflectors. A single reflector controlled by a stepping motor and an array of fixed reflectors were used. The width of the beam of the infrared rays is measured and the relationship between the width and the stepping angle deviation of the motor are demonstrated. Moreover, the received power, the bit error rate, and throughput of the proposal scheme are measured. The angle of the reflector and the reflection characteristics when using one or two reflectors were compared. In addition, the throughput characteristics of the proposal scheme were made clear by experiments.

  In this research project, a hybridvisible light and radio communication for location-specific services inintelligent transportation system is studied. This location-specificcommunication using visible light allows the receiver at the vehicle to displayto the driver only that traffic information which is relevant to the location, whichthe vehicle is. Moreover, the drivers will not be bothered with trafficinformation irrelevant to them (e.g. those only relevant to neighboring lanes)and the user experience is improved. Nevertheless, it is well known that VLCcannot compete with radio frequency (RF) systems when it comes to long-distancetransmission. A hybrid system that makes use of VLC and RF communication is proposedto solve the above problem. In the proposed hybrid system, the transmittedinformation is divided between the VLC channel and the RF channel. VLC channelis used to maintain the positioning capability and RF channel is used to sendmost of the information. The theoretical work and simulation have been done toshow the effective communication area and the receivable information can beincreased by using the proposed system compared with a pure VLC system. 

光無線通信は，低コスト，電波と干渉しない、法規制を受けにくい，低消費電力を実現可能といった特徴から，データ通信の一手法として注目されてきた。一方で、電波通信とは異なる、いくつの技術的な困難を伴う。その中でも特に困難な問題として、ビームの幅と到達距離のトレードオフが挙げられる。具体的には、光ビームの幅を狭めることにより電力を集中すれば、伝播損失が少なくなり、誤り率特性の劣化を小さくできる。しかし、光は直線で伝搬するため、送信器ビームと受信器の位置を合わせなければ通信ができないため、ビームが狭くなればなるほど、通信可能な範囲が狭くなる。最も容易な解決方法はビームフォーミング方式を利用することであるが、光は周波数が非常に高いため、RFと同様に光信号の位相を調整する方法を用いたビームフォーミング方式は適さない。この問題を解消するため、著者らは、拡散した光ビームを使いながら移動端末が存在する場所に目的とする副搬送波のみをビームフォーミングにより効率良く伝送する、RF副搬送波ビームフォーミング方式を提案する。本研究では光無線通信を移動体通信に適用した場合について考察を行った。著者は以下の手順で進んでいた。まず、光チャンネルとして、外部の背景光雑音やその他のノイズの影響を考慮し、シミュレーションを行い、通信BER(Bit error rate)と光受信電力の関係を明らかにした。結果から、光受信電力が一定の閾値を超えると、良い性能の光無線通信ができることを証明した。次に、閾値以上の電力を達するため、送信機の配置位置、距離などをシミュレーションで考察した。また、ビームパターンを設計し、ビームの電力分布様子を明らかにした。ビームの電力分布を分析した結果、RF副搬送波ビームフォーミング方式が有効であると証明した。