一种面向电池供电中继节点的中继选择方法

在协作通信网络中,信道条件较好的电池供电中继节点可能被频繁选择用于数据转发,导致电量快速消耗,甚至缩短网络生命周期。针对该问题,提出一种兼顾电池能耗、电池余量和信道状态信息的中继选择方法。根据节点电池能耗与电池余量的比值对链路的信噪比加权,选择加权后中继链路信噪比最大中继链路的源节点或中继节点发送数据。推导系统的平均转发信道容量和中断概率表达式,在此基础上的仿真结果表明,该方法在保证转发信道容量和中断性能的同时,能有效降低中继节点的电池能耗,延长协作通信网络的生命周期。     

窃听环境下轮流中继网络的安全传输方案

针对含有多个窃听者、多个中继的无线通信网络的传输安全问题,提出了一种新的轮流中继安全传输方案。以降低系统平均安全中断概率为目标,所提方案在源节点发送保密信息的过程中,在每个传输时隙均选择一个最优中继对前一时隙接收到的信号进行转发以干扰窃听者,并在目的节点处进行干扰消除。为评估系统性能,推导得到了系统平均安全中断概率的闭式表达式。仿真结果验证了理论分析结果的正确性,并表明与传统中继协作方案相比,所提方案可显著降低系统的平均安全中断概率。     

无线能量收集协作系统的节能中继选择方法

在无线能量收集协作通信系统中,针对中继处可能出现的能量瓶颈,提出优化源节点和中继的传输功率的节能中继选择方法。利用源节点与中继之间发射功率的比例关系计算源节点的发射功率,选择信道容量最大的中继链路进行数据转发,并考虑源节点与中继的发射功率约束。在此基础上,推导系统的平均信道容量和中断性能。仿真结果表明,该方法可显著提高系统能量效率,节约源节点的能量消耗。     

多中继混合转发协作传输策略研究

为了优化多中继协作通信系统的性能,提出了一种多中继混合转发协作传输策略(Multiple-Relay Hybrid-Forwarding Cooperative Transmission Scheme,MRHF-CTS)。该策略考虑多中继协作通信系统中的译码转发与放大转发以及两种转发方式带来的性能缺陷,根据协作中继节点接收信号的译码结果选择转发方式,同时引入协作中继节点之间数据来传输对系统性能的增益。对系统中断概率性能进行了推导与分析,结果表明,该策略在消除放大转发策略噪声累积的基础上,能够有效抑制协作中继节点错误检测译码转发给系统带来的不利影响,明显提升系统性能;在大信噪比情况下,可获得多中继译码转发协作通信系统的最佳性能。     

基于中继联合优化选择的物理层安全方案

针对认知无线电(CR)网络中的安全传输问题,提出基于传输中继和干扰中继联合优化选择的物理层安全方案。在主用户网络和次用户网络共存的环境中,通过优化选取协作传输中继和协作干扰中继实现信息的安全传输,并分析推导出瑞利衰落环境下该方案保密中断概率的闭式表达式。仿真结果表明,在不同参数场景下,该方案均可实现较低的保密中断概率,提升CR网络的信息传输安全性能。     

中继通信系统中的功率分配研究

对中继协作通信系统中的功率分配问题进行了研究。给出了多中继协作通信网络模型,针对该模型,分析了等功率分配、中断概率最小的功率分配、传输速率最大的功率分配和节点选择功率分配等四种功率分配方案,从数学上对各种方案的实现进行了描述,并对各种方案能否实现功率的优化配置及实现难易程度进行了讨论。     

基于能量收集技术的无线协作网络中继选择

针对目前能量收集技术能够收集到的可用能量受限,导致无线协作网络中继节点处易出现能量短板的问题,为了避免整个网络因中继节点大量死亡而瘫痪,提出了一种基于能量收集技术的无线协作网络中继选择方案,即联合最大能量和最大数据传输链路的中继选择方案。首先,基于节点的能量收集状况,选出每跳中能量最大的节点进行解码转发;然后,结合每连续两跳的链路传输状态,选出与源节点和目的节点之间的数据传输信道最优者作为中继节点。结合Nakagami-m信道衰落模型,将该方案与随机选择方案、最大数据链路信道增益(MaDs)方案和基于中继-窃听链路最小信道增益(BNBF)方案进行对比分析,结果表明:在满足收集的能量足够用于下一时隙能量收集和数据传输的前提下,用于能量收集的比例越小,网络中断概率越小;联合最大能量和最大数据传输链路的中继选择方案在网络中断性能方面优于其他方案,其中断概率随信噪比的增大而减小,特别是当平均信噪比为38dB时,网络中断概率降到10^-5。     

VANET中基于约束区域中继的协作通信性能研究

研究了协作通信对车载自组织网络(VANET)性能的影响。中继节点参与通信会提高单链路传输的可靠性,然而大多数研究忽略了采取中继节点会扩大通信干扰范围的影响,从而带来的额外干扰也会影响其他链路的通信。为此,通过构建一个菱形的中继节点选择区域来限制增大干扰区域的不利影响,进而提出一种新的评估协作通信性能的方法,并得到中断概率和网络吞吐量的数学表达式。数值分析和仿真结果表明,协作通信能够显著降低通信中断概率,但其对整个网络的吞吐量性能并不总是有效的,合理地设置中继选择区域大小能有效提高网络吞吐量。     

窃听环境下协作通信网络的机会中继选择方法

传统的最佳中继选择方法仅依赖于合法用户的信道条件,在存在窃听用户的环境中无法保证信息传输的安全性与私密性。针对该问题,以最小化系统安全中断概率为目标,综合考虑合法用户与窃听用户的信道状态信息,提出一种新的机会中继选择方法。针对解码转发协作通信网络,给出系统总发射功率受限条件下的最佳功率分配方案,并在此基础上设计最佳中继节点的选择方法,推导得到系统安全中断概率的闭式表达式。仿真结果验证了该闭式表达式的正确性,并表明与传统中继选择方法相比,提出的中继选择方法可显著降低系统的安全中断概率。     

MIMO系统中的最优中继选择方案

研究多输入多输出中继系统中基于放大转发协议的最优中继选择方案,推导出中断概率和平均信道容量的闭式表达式,并对不同中继节点数时的中断概率和平均信道容量进行仿真。结果表明,该方案可以有效降低系统中断概率,且随着中继节点数的增多,系统平均信道容量优于直接传输方案。     

Relay selection for maximizing the number of successive transmission in cooperative networks

Relay selection has an important effect on improving the performance of cooperative communication system. However, the frequent operation of relay selection can bring enormous control message overhead, and then decrease the performance of cooperative communication. To reduce the relay selection frequency, in this paper, we propose a relay selection scheme to choose the best relay considering successive packets transmission. In this scheme, through the parameters of data transmission rate, the length of data packet and the estimated channel state information, the best relay is selected to maximize the number of successive packets transmission while guaranteeing the given outage probability. It is proven by numerical results that the proposed relay selection scheme can support the successive packets transmission in cooperative wireless networks and the maximum number of successive packets transmission is affected by the different network parameters, i.e. packet length, data transmission rate, signal to noise ratio and Doppler frequency. Compared to previous relay selection schemes by simulation results, it is shown that the proposed relay selection scheme can improve the throughput performance efficiently.     

工业5G的D2D多跳中继辅助传输方法及中断性能分析

面向工业5G网络的超可靠强实时传输要求,研究基于设备到设备通信（device-to-device,D2D）的多跳多中继辅助传输方法。基于随机几何理论,采用泊松点过程对工业现场设备进行建模,并划分中继选择区域。多跳中继过程中,每一跳中继选择信干噪比最大的节点进行解码转发,充分考虑层叠部署的多条D2D传输路径上的节点干扰以及随机噪声,推导出端到端中断概率的闭式表达式。仿真分析了中继节点部署密度、发射功率、路径距离等因素对端到端中断概率的影响。结果表明,采用多跳多中继辅助的D2D传输可以大幅降低工业5G网络的端到端中断概率,提高传输可靠性。     

Optimal algorithm for Multi-hop relay selection based on cognitive radio

Relay selection, also called opportunistic relay, is capable of fast narrowing the search scope, finding the optimal relays and achieving a better cooperative transmission. With the continuous expansion of network capacity, the coverage area and the participating relays, it is unwise to traverse all the nodes to select the best relay. An optimal scheme based on cognitive wireless multi-hop relay selection has been proposed in this study, in which a threshold value is set for the signal-to-interference-plus-noise ratio (SINR). Only when the SINR exceeds the threshold can the node be selected as the relay node. Because of the random distribution and geographical universality of the relay, the candidate relays would better be limited within a particular area. Then a model based on stochastic geometry is established to rapidly find the relay which meets the demand near optimally, without needing of the global channel state information of the network in advance. The simulation results show that the optimized scheme can reduce the searching time and improve the performance of the secondary transmission. In addition, theoretical formula of the outage probability and channel data transmission rate has also been derived and verified its effectiveness through simulation.

     

一种双信道协作中继的认知网络功率分配算法

针对认知无线网络主、次用户的互相干扰对网络中断性能以及系统传输效率的影响进行了研究,采用一种双信道协作中继的传输方案来减少干扰,并提出一种基于中断概率的最优功率分配方案来改善中断性能和传输效率。在该传输方案中,主、次系统通过对接收的主信号和复合信号进行处理,采用连续的干扰解码和消除得到去干扰信号。该功率分配方案在保障主系统中断性能的前提下,提出次系统中断概率的优化方程,通过关联功率分配因子来实现最大化次系统吞吐量。实验结果表明,该算法在改善中断性能和系统吞吐量方面具有较好的效果。     

Joint relay selection and power control for robust cooperative multicast in mmWave WPANs

We propose an optimization algorithm for joint relay selection and source and relay power allocation under mixed line-of-sight (LoS) and non-LoS path scenarios for both power saving and robustness enhancement of cooperative multicast in millimeter-wave wireless personal area networks. Our aims are to reduce power consumption and enhance the robustness of cooperative multicasts in millimeter-wave wireless personal area networks. First, we describe a novel beam training protocol that is capable of overhearing and information feedback to filter relay candidates with non-LoS links and avoid selecting relays for transceivers with LoS paths. Second, the joint relay selection and power allocation issue is formulated as an optimization problem with the objective of minimizing the maximum combined power consumption of the source and relay under maximum tolerable outage probabilities and transmit powers. By introducing relaxation and Lagrange multiplier methods, a closed-form expression for the joint relay selection and power allocation is obtained. Finally, simulation results indicate significant improvements in terms of both outage probability and power consumption over the conventional combined transmit power minimization algorithm.     

A simple amplify-and-forward opportunistic relaying based on outdated channel state information

Opportunistic relay selection(ORS)is a promising approach for cooperative communications owing to its low complexity by activating only the best relay.However,in mobile scenarios,the channel state information(CSI)estimated in relay selection may be different from the actual CSI employed in data transmission due to relatively fast varying channels,i.e.,CSI is outdated,which may lead to incorrect relay selection,and hence system performance deteriorates.To address the problem,this paper designs a relay selection strategy with instaneous and statistical CSIs in amplify-and-forward(AF)cooperative networks whose instantaneous CSIs of two hops employed in relay selection are both outdated.Based on high signal-to-noise ratio(SNR)analysis,we propose a distinctive relay selection strategy which can be described as selecting the relay with the asymptotic optimum average symbol error probability(SEP)and outage probability at high SNR.The corresponding asymptotic outage probability and SEP performance analysis are also provided.Finally,simulation results not only validate our theoretical analysis,but also show that in asymmetrical outdated CSI scenarios,the proposed strategy achieves better performance than existing relay selection strategies at medium and high SNR values.     

同步协作中继系统的波束形成通信方案的设计*

从多输入多输出（multiple-input and multiple-output,MIMO）系统所设计的Alamouti码中得到启发,针对在无线协同信道之上的同步协作中继系统提出了一种新的通信方案。为了在大中断率和低成对误码率(PEP)的情况下能有效地传送信号,源天线采用功率分配波束形成技术,中继节点采用放大转发(amplify and forward,AF)技术。研究和仿真表明,对给定效率R,所提出的模型与以前的通信方案尤其是广播通信模型相比,在中断率和成对误码率上都有明显的改善。这一发现可能会对未     

基于协作通信技术的无线再生中继网络中的功率最优分配

针对无线再生中继网络的系统性能与系统误帧率、中断概率等有关问题,以协作通信技术中的多用户协作分集协议MDP(Multi-user Diversity-cooperative Protocol)为基础,设计了新型的MDPTS(Multi-user Diversity-cooperative Protocol Transmission Scheme)传输方案,优化了信号传输过程,提升了信号传输效率与网络吞吐量。在此基础上以系统误帧率最小为目标,提出了在发射端和中继器间的功率分配方案,以误帧率下届为目标函数,通过拉格朗日法求得系统的功率分配最优解。仿真结果表明,与采用传统传输方案的网络相比,采用MDPTS传输方案的网络具有更高的分集增益和复用增益,因此系统性能也更好。