Energy-Efficient and Reliability-Driven Cooperative Communications in Cognitive Body Area Networks

We study the potential of cognition and cooperation in Body Area Networks (BANs). On one hand, most BAN-based applications involve end-to-end transmission across heterogenous networks. Cognitive communication has been known to be an effective technology for addressing network heterogeneity. On the other hand, a BAN is normally required to provide reliable communications and operate in a very low power level to conserve energy and reduce the electromagnetic radiation impact on human body. Cooperative communication has been known to enhance the transmission reliability and maintain low transmission power. However, the joint cognitive and cooperative mechanism has not been investigated yet in the literature. In this paper, we propose a network architecture for cognitive and cooperative communications in BANs. An intelligent mobile device is introduced as either a cognitive gateway to interconnect heterogenous networks; or a cooperative relay node to achieve transmission diversity. Two cooperative transmission schemes, Energy-conserved Cooperative Transmission and Reliability-driven Cooperative Transmission, are presented for different applications that have distinct energy consumption or reliability requirement. Optimization problems are formulated to optimally allocate power in the cooperative transmission. Results indicate that cooperative transmission schemes can significantly decrease Bit Error Rate (BER) and reduce energy consumption, compared to the non-cooperative schemes. The BER gain is over one order in the high SNR region, while the energy consumption can save up to 50% in the low BER region.     

A Survey of Cooperative Games for Cognitive Radio Networks

Cooperative cognitive radio networks are new cognitive radio paradigm. Cooperative communication approaches, such as cooperative spectrum sensing and cooperative spectrum sharing, are playing key roles in the development of cognitive radio networks. To achieve the high performance, a cooperative cognitive communication framework is often used to model various cooperative spectrum sensing or sharing scenarios. However, its implementation faces numerous challenges due to the complexity of mobility and traffic models, the needs of dynamic spectrum access, the heterogeneous requirements from different users, and the distributed structure of the network. Fortunately, cooperative game theory can be used to formulate and model the interactions among licensed and unlicensed users for spectrum sensing and spectrum sharing to efficiently allocate spectrum resource in the highly dynamic and distributed radio environment. In this paper, we first present the cooperative communication technologies and describe their existing challenges, then introduce different game solutions, after that, we discuss several cooperative game strategies, and analyze the associated their applications in cognitive radio networks, at final, some open directions for future research on economic strategies in cooperative communication in cognitive radio networks are proposed.     

噪声不确定下基于进化博弈论的 协作频谱检测研究

认知无线电中,协作频谱检测已经被证明可以有效提高系统的检测性能。但是在噪声不确定的情况下,认知用户会更加倾向于减少检测消耗来提高自身的吞吐量。本文主要是把进化博弈论应用到噪声不确定下的协作频谱检测中,认知用户可以动态地选择是否参加协作频谱检测,通过不断的迭代学习,得到一个进化稳定策略（ESS）。本文把所有认知用户作为整体参与博弈,由进化博弈论算法,得到其参与协作的认知用户平均吞吐量,并将其与所有用户的平均吞吐量对比。如不等则反复迭代直至相等,从而得到最终的进化稳定策略。仿真结果表明:噪声不确定度越高,达到平衡时认知用户参与协作检测的概率就越高;进化博弈论算法让认知用户选择性地参与协作检测比让所有用户都参与协作检测有更高的系统吞吐量。      

Modeling Mobility in Cooperative Ad Hoc Networks

This paper addresses issues concerned with design and managing of mobile ad hoc networks. We focus on self-organizing, cooperative and coherent networks that enable a continuous communication with a central decision unit and adopt to changes in an unknown environment to achieve a given goal. In general, it is very difficult to model a motion of nodes of a real-life ad hoc network. However, mobility modeling is a critical element that has great influence on the performance characteristics of a cooperative system. In this paper we investigate a novel approach to cooperative and fully connected networks design. We present an algorithm for efficient calculating of motion trajectories of wireless devices. Our computing scheme adopts two techniques, the concept of an artificial potential field and the concept of a particle-based mobility. The utility and efficiency of the proposed approach has been justified through simulation experiments. The results of presented case studies show a wide range of applications of our method starting from simple to more complex ad hoc networks.     

A Low Complexity High Resolution Cooperative Spectrum-Sensing Scheme for Cognitive Radios

Conventional distributed cognitive radio (CR) communication aims to increase the sensing accuracy and reduce the detection time by allowing the CR users to operate in the same frequency band in a cooperative fashion and by forming efficient decision making. In this paper, we propose a spectrum-sensing scheme which provides accurate detection at low complexity, by assigning different sensing tasks to the CRs. If the number of cooperative CRs is N, our method offers an effective sensing resolution of N times higher than that of the conventional method. An inherently low complex progressive decimation filter bank, which provides variable sensing resolutions by software reconfiguration, is employed at each CR. The design example shows that the hardware complexity of our sensing scheme is 41.3% less than that of the conventional spectrum sensor. It is also shown that the proposed system can support multiple communication standards.     

Cooperative communication based access technique for sensor networks

ABSTRACT

The collaboration of users in communication systems is defined as cooperative communication. The cognitive radio, i.e. dynamic spectrum access technique, is a wireless communication technology that provides a great chance for unlicensed users to exploit the frequency bands in an opportunistic way. A wireless sensor network is a widely used communication technology composing of spatially distributed independent sensors in order to monitor physical or environmental circumstances. In this work, a new technique that unlicensed users become a cooperative relay when they are in idle mode is proposed. Along with the proposed technique, unlicensed users help sensor nodes as a cooperative relay when they are in idle mode. Similarly, sensor nodes help unlicensed users for detecting idle frequency bands while in sleep mode. By preventing any disruption that remote users may be exposed owing to signal attenuation, the proposed cooperative relay utilises amplify and forward based cooperative communication protocol. Thanks to this approach; the overall network has greater performance than wireless sensor network that does not use cooperative communication based dynamic access technique in terms of throughput, energy, and delay.     

同步协作通信的发送方时延性能比较

同步协作是计算机支持的协同工作研究的一个重要领域。同步协作对通信提出了多点性、可靠性、可规模化和低时延性的要求。笔者比较了基于两种ＩＰ通信技术（单播和多播）的可靠协作通信的时延特性,并得出了支持同步协同通信的设计方案准则：在低网络差错率下采用多播通信在高网络差错率下,采用单播通信。     

A distributed and policy-free general-purpose shared window system

Shared window systems allow collaboration transparent, single-user applications interacted with on multiple users' workstations, enabling the members of a cooperative ensemble to simultaneously share and revise information. The paper presents a system capable of sharing applications running under the X Window System. In contrast to previously implemented systems, the present shared window system addresses issues that are crucial for general-purpose use. The shared window system is policy-free, i.e., there are no preferred policies for handling issues such as admission and floor control. Instead, it offers a set of essential mechanisms on top of which various policies and user paradigms may be realized. Further, the system distributes the sharing functionality among all sites involved in a cooperative activity. Measurements have shown a positive impact of this on the overall performance of the system and thus justified the viability of the design decisions taken     

Supporting Mobile Collaboration in Spatially Distributed Workgroups with Digital Interactive Maps

Following the mobile computing trend, business logics of distributed, cooperative applications started to move into the mobile client applications. With this shift, the cooperation aspect may also exploit the user??s location and situation context and integrate it into the actual collaboration. In this article, we present an approach for a Collaborative Map that exploits the spatial context of the members of a distributed group as a means to visualize and provide collaboration functionality. Then, a number of location-related cooperation methods become feasible such as getting an overview of the spatial distribution of team members, identify an ad-hoc meeting place nearby, or chat with a group member who has a certain expertise in his profile. With CoMa, we move from standard collaboration tools that marginally consider spatial information towards context-aware mobile collaborative systems that can support a wide range of applications where human resources have to be coordinated in a spatial context and tasks need to be assigned dynamically depending on capabilities and situation context.     

基于认知无线电的无线通信研究现状

归纳了从软件无线电到认知无线电功能的演进。认知无线电是在软件无线电的基础上提出的智能化的无线通信技术,它着力解决频谱资源的有效利用问题;认知无线电概念的提出将对现行的频谱管理体制提出挑战,并给无线通信带来新的发展空间。软件无线电在其系统硬件无需变更的情况下,可以在不同的时候根据需要通过软件加载来完成不同的功能。认知无线电可以感知周围电磁环境,通过无线电知识描述语言（RKRL）与通信网络进行智能交流,并实时调整传输参数,以达到无论何时何地都能达到通信系统的高可靠性和频谱利用的高效性。文中在此基础上探讨了认知无线电技术未来发展值得关注的热点问题。     

Adaptive intervehicle communication control for cooperative safety systems

Vehicular ad hoc networks play a critical role in enabling important active safety applications such as cooperative collision warning. These active safety applications rely on continuous broadcast of self-information by all vehicles, which allows each vehicle to track all its neighboring cars in real time. The most pressing challenge in such safety-driven communication is to maintain acceptable tracking accuracy while avoiding congestion in the shared channel. In this article we propose a transmission control protocol that adapts communication rate and power based on the dynamics of a vehicular network and safety-driven tracking process. The proposed solution uses a closed-loop control concept and accounts for wireless channel unreliability. Simulation results confirm that if packet generation rate and associated transmission power for safety messages are adjusted in an on-demand and adaptive fashion, robust tracking is possible under various traffic conditions.     

Role-based collaboration and its kernel mechanisms

Computer-supported cooperative work (CSCW) systems are computer-based tools that support the collaborative activities of human users. They should not only support virtual face-to-face collaborative environments but also improve face-to-face collaboration by providing more mechanisms to overcome the drawbacks of usual face-to-face collaboration. Introducing roles into CSCW systems is important in achieving this. This paper's contributions include establishing the requirements for a role-based collaboration, presenting the concept, requirements, and principles of role-based collaboration, proposing a model E-CARGO for role-based collaboration, and describing the kernel mechanisms and their implementation to facilitate the development of role-based collaborative systems for industrial applications.     

Two-Way Secure Communication with Multiple Untrusted Half-Duplex AF Relays

Wireless Personal Communications - In this paper, we analyze the secrecy outage probability (SOP) of a cognitive cooperative radio network in a two-way communication in which two secondary source...     

Cooperative MAC Design in Multi-Hop Wireless Networks—Part II: When Source and Destination are Two-Hops Away from Each Other

Ubiquitous and pervasive computing and networking are envisaged as part of the future 5G wireless communication landscape where devices which are multi-hops away from each other are connected in a cooperative way. In this paper, we investigate a challenging case in cooperative communications where source and destination are two-hops away from each other. From the perspective of MAC design, we propose a novel MAC protocol which enables two-hop cooperative communications by involving one or more one-hop neighbors of both source and destination as the relays for cooperative communication. To do so, a concept referred to as Multiple Relay Points (MRPs) has been introduced and the MRPs are selected by jointly considering the link quality of both hops. In addition to employing a static scheme which always uses a fixed number of relays for cooperative communication, we have also proposed an adaptive scheme which can optimally adjust the number of relays flexibly according to channel conditions. Through performance evaluation and comparison with the original IEEE 802.11 based scheme, we demonstrate that more reliable communications, reduced transmission power and significant throughput improvement can be achieved by using our two-hop cooperative MAC protocol, especially when operated in the adaptive mode.     

Joint cooperative spectrum sensing and channel selection optimization for satellite communication systems based on cognitive radio

Cognitive radio has attracted considerable attention because of its ability to make full use of the available spectrum resources for wireless terrestrial communication networks. In addition, the satellite communication scenario, which requires a transparent air interface to integrated/hybrid Satellite–Terrestrial communication systems and provides a supplement for other multimedia services, will cause frequency scarcity. Satellite communication systems based on cognitive radio are available under scenarios that involve transmission with changing communications. In this paper, a cooperative spectrum‐sensing algorithm based on a time or bandwidth‐based cooperative spectrum‐sensing model of an integrated/hybrid cooperative satellite communication system is proposed. Moreover, the concept of weighted cooperative spectrum sensing is introduced. Compared with the traditional single‐user spectrum‐sensing algorithm, the cooperative spectrum sensing is able to cope with the interference to the primary user caused by a secondary user better. In addition, multiple earth stations that use some part of the bandwidth cooperatively to perform spectrum sensing throughout the whole frame can detect the presence of primary user in time. The satellite component combines the sensing results from earth stations to reach a final decision, and the optimal combination weights to maximize the detection probability of the secondary user are obtained. Numerical results that demonstrate the performance of the proposed algorithm are presented. Copyright © 2015 John Wiley & Sons, Ltd.     

Collaborative Relaying Strategies in Autonomic Management of Mobile Robotics

Mobile robotics is a field that presents a surprising set of challenges to communications. One concept that can result in radically different solutions in mobile robotics is that of collaborative and cooperative communications. Cooperative techniques in wireless networks can enhance the performance of communication especially in cases where a small number of robots can be used to aid the establishment of reliable and efficient communication links. In this paper, we present a scenario for hybrid mobile robotics, where a small number of carriers are able to reposition nodes according to communication needs. We developed a common information management layer in order to coordinate cooperation (including communication aspects) between all units (information nodes and robots) according to high level self-established policies. We select IEEE 802.11 technology as the technology for the communication infrastructure and explore its potential for cooperative mobile environments in terms of power and spectrum efficiency presenting the rules required to reconfigure such a mobile robotic environment.     

联合RSSD和TDOA技术的认知协同定位算法研究

在认知无线网络通信中,主用户的位置信息对于认知用户借用信道接入通信具有重要意义,通过协同定位技术来提高定位性能已成为当前认知无线电领域研究热点之一。论文提出了一种基于RSSD/TDOA技术的协同定位算法,该算法适用于对主用户发射功率和主用户信号发射瞬时时间等先验知识未知的应用场景。算法首先通过凸包算法对主用户的位置进行识别,然后再采用RSSD/TDOA协同算法对主用户进行定位,并通过顽健性较强的泰勒级数展开法来提高定位精度。仿真结果表明,论文所提的在认知无线网络中实现对主用户定位的算法相比较而言具有更高的定位精度和时效性。      

无线协作网络中基于数据传输需求的分布式功率控制

在未来无线通信网络中,协作通信的性能依赖于通信资源的有效分配,比如中继选择和功率控制等.在本文中,我们建议了一个分布式买者和卖者博弈理论框架,以满足用户链路质量需求为基础,解决多用户协作通信中最优化中继选择和功率控制.本文联合考虑了源节点和中继节点的功率分配,进而优化源节点和中继节点的收益.这里提出的方法不仅有助于源节点找到相对位置较好的中继节点以及在源和中继之间进行最优化功率分配从而最小化源节点的支付,而且有助于相互竞争的中继节点提供优化的价格以最大化它们各自的收益.此外,这里的优化价格可以仅由局部信道状态信息和其他节点的能量价格决定.如果获得的中继节点总数增加,全网的能量消耗会更低.     

Applying an information gathering architecture to Netfind: a whitepages tool for a changing and growing Internet

The Internet is quickly becoming an indispensable means of communication and collaboration, based on applications such as electronic mail, remote information retrieval, and multimedia conferencing. A fundamental problem for such applications is supporting resource discovery in a fashion that keeps pace with the Internet's exponential growth in size and diversity. Netfind is a scalable tool that locates current electronic mail addresses and other information about Internet users. Since the time we first deployed Netfind in 1990, it has evolved considerably, making use of more types of information sources. As well as more sophisticated mechanisms to gather and cross-correlate information. In this paper, we describe these techniques, and present a general framework for gathering and harnessing widely distributed information in a diverse and growing Internet environment. At present, Netfind gathers information from 17 different types of sources, providing a particularly thorough demonstration of an information gathering architecture     

Cooperative communications with relay selection for wireless networks: design issues and applications

Relay selection schemes for cooperative communications to achieve full cooperative diversity gains while maintaining spectral and energy efficiency have been extensively studied in a recent research. These schemes select only the best relay from multiple relaying candidates to cooperate with a communication link. In the present paper, we reviewed recently proposed cooperative communication protocols that integrate with relay selection mechanisms. The key design issues for relay selection mechanisms, for example, relaying candidate selection, optimal relay assignment, and cooperative transmission, were identified. We further discussed the challenges of optimal relay assignment in multi‐hop wireless sensor networks and presented the potential applications of cooperative communications with a relay selection in such networks. Future research directions were outlined, for example, the issues of service differentiation and system fairness in cooperative communication systems and the joint use of game theory and adaptive learning techniques in relaying candidate selection and optimal‐relay assignment mechanisms for efficient allocation of network resources. Copyright © 2011 John Wiley & Sons, Ltd.