直达链路下的全双工能量采集中继系统的吞吐量分析

针对三节点传输系统,研究了基于时间切换能量采集的全双工放大转发协作中继方案。考虑源和目的地之间存在直达链路,全双工中继节点采用天线选择技术以最小化中继自干扰,目的节点采用最大比合并技术以最大化目的地接收信噪比。在延迟受限传输模式下,推出了自干扰信道增益为常数时系统吞吐量近似闭合表达式。运用最佳目的地选择策略和自适应中继选择策略讨论了系统吞吐量性能。如图4所示,在源发送功率为30 dB时,就系统吞吐量而言,本文算法比其他两种算法分别提高了0.22 bits/s/Hz和0.68 bits/s/Hz。数值分析和蒙特卡洛仿真表明,增加中继个数,增加目的地个数或者增大能量采集效率均能够提升系统吞吐量性能。      

多中继与多用户选择的中继系统安全性能分析

为了考察使用多中继选择与多用户选择的放大转发（AF）中继系统的物理层安全性能,推导了其在瑞利衰落信道上和联合发送天线选择/接收最大比合并天线分集下的非零安全容量概率和安全中断概率的精确表达式以及在高信噪比下的渐近安全中断概率解析表达式。AF中继系统的非零安全容量概率和安全中断概率的数值计算和仿真结果相吻合,验证了以上理论分析的正确性;分析结果表明,其安全分集增益为源节点发射天线数、最优中继节点接收天线数、中继节点数的三者乘积与最优中继节点发射天线数、最优用户接收天线数、用户数三者乘积之间的最小值,且与窃听信道无关。     

基于中继择优选择的协同ARQ吞吐量分析

本文分为两个部分:基于中继择优选择,分析选择多个中继情况下系统的中断概率;考虑系统延时,仅仅对双中继协同系统、单中继协同ARQ系统和双中继协同ARQ系统的吞吐量进行比较。理论分析和仿真结果说明,协同系统最优中继选择个数越多,系统中断概率就越小;选择单个中继和两个中继的协同ARQ系统的吞吐量,无论高信噪比还是低信噪比情况下,都明显优于非ARQ协同系统。     

基于能量采集的全双工中继系统时隙优化

针对能量采集基础上的全双工中继系统时隙优化问题,以双跳能量采集全双工中继系统为模型,基于中继工作于时间分割模式,分析了在放大中继转发协议与译码中继转发协议下如何实现系统吞吐量最大化,对能量采集时隙进行了优化研究,推导了瑞利衰落信道下最佳能量采集时间的具体表达式,在仿真中对比了全双工中继系统与半双工中继系统的吞吐量。通过性能分析与仿真实现可知,全双工中继技术可以提高频谱利用效率、系统吞吐量,满足日益增长的高速率要求。     

多接入中继信道中的单中继选择

研究表明,协作中继选择能提高无线中继网络的鲁棒性和能效。文中研究一个多接入中继信道,包含2个信源,N个中继和1个信宿。中继节点为半双工,对两个信源的信号采用非再生的网络编码。考虑直接链路,基于最佳最差信道、最佳信噪比和最佳调和平均选择,提出新的选择策略。仿真结果表明其在性能上优于原有策略。     

一种联合链路持续时间与平均速率的中继选择方法

针对中继系统中节点快速移动时采用传统中继选择方法造成系统可传输数据量较低的问题,提出一种联合链路持续时间与平均速率的中继选择方法.该方法首先分析了系统采用两跳传输及协作传输两种模式下的链路持续时间,分别给出了节点速度及相互之间距离满足不同条件时的链路持续时间表达式,然后计算两种模式下的链路平均可达速率,最后基于所提出的准则完成中继选择.仿真结果表明,与传统的中继选择方法相比,该方法可以使系统获得更多的数据传输,同时具有较低的中断概率.     

多用户MIMO—CDMA系统下行链路设计及MATLAB仿真

MIMO(Multi-Input Multi-Output)技术是最可能应用到未来无线通信系统中的关键技术之一,多用户MIMO-CDMA是MIMO技术领域研究的最新发展。文章概述了多用户MIMO-CDMA下行链路的系统结构,提出了一种基于帧结构的可供DSP实现的多用户MIMO-CDMA全系统的仿真模型,接收端采用MRC最大似然接收提高了系统的接收分集增益,最后对不同用户数和不同PN长度条件下的多用户MIMO-CDMA系统进行了性能分析和评价。     

中继回程链路下的HARQ技术实现

针对Type Ⅰ中继回程链路设计中的HARQ技术实现问题进行讨论,在已有LTE系统标准中对HARQ技术实现细节定义的基础上,结合中继回程链路设计特点,重点讨论了HARQ定时、子帧分配等具体实现细节,分析了出现的主要问题,并给出了对应的解决方案,在中继回程链路HARQ实现中既考虑了与已有LTE系统标准的后向兼容,又简化了...     

能量收集双向中继网络的中继选择和功率分配

结合能量收集技术,研究了放大转发双向中继网络的系统性能。基于双向中继系统中的两个端到端信噪比平衡准则,推导出了单中继选择情况下信源最优的功率分配方案和中继最优的能量收集比例。仿真结果证明所提方法能够实现最好的系统性能。通过比较发现,能量收集双向中继网络比传统双向中继网络能够实现更高的传输速率。     

Relay Selection and Performance Analysis of Wireless Energy Harvesting Networks

Wireless Personal Communications - We proposed an integrated information relay and wireless power supply assisted RF energy harvesting-based cooperative dual-hope decode-and-forward (DF) relaying...     

Secure Energy Harvesting Communications with Relay Selection over Nakagami-m Fading Channels

In this paper, an energy harvesting relay network over Nakagami-m fading is investigated. In the considered system, the power beacon can provide wireless energy for the source and relays which deploy time-switching-based radio frequency energy harvesting technique. Two relay selection schemes, namely partial relay selection and optimal relay selection, are proposed in order to enhance the system performance. In the former, the source only has the channel state information of the first hop, while in the latter it has the full knowledge of the channel state information. The eavesdropper is able to wiretap to the signal transmitted from the source and the relays. The exact closed-form expressions of secrecy outage probability are derived. The results show that optimal relay selection performs better than partial relay selection. With increasing number of relays, the considered system shows better performance. In addition, the energy harvesting duration has a significant effect on the secrecy outage probability.     

能量收集双向中继网络的高能效联合中继选择和功率分配算法

为了实现双向中继系统在满足传输速率要求时的最小功率消耗,基于功率分割中继协议,在完美和非完美的信道估计两种不同的情况下,提出了能量收集双向中继网络的高能效联合中继选择和功率分配算法,得到了两个信源的最优功率分配和中继节点最优的能量收集比例.仿真结果表明,信道估计误差会增加系统的功率消耗;与传统双向中继比较发现,能量收集双向中继能够实现更少的系统功率消耗.     

Joint Source and Relay Precoder Design in Amplify-and-Forward MIMO Relay Systems with Direct Link

This paper investigates the precoder design problem in a two-hop amplify-and-forward multiple-input-multiple-output relay system. Many previous works on this problem are based on the minimum mean-square error criterion and the presence of a direct link between the source and the destination is ignored. In this paper, we propose a new method for joint source and relay precoder design based on maximizing the mutual information between the source and the destination, taking both the relay link and the direct link into account. In contrast to previous works, which consider the transmit power constraints of the source and the relay independently, we assume a total power constraint on the sum transmit power of the source and the relay instead to study also the optimal power distribution over the two nodes. A constrained optimization problem with respect to the unknown source precoder matrix and relay precoder matrix is then formulated, which is nonconvex and very difficult to solve directly. We propose a structural constraint on the precoders by analyzing the structure of the problem and referring to related works. With the proposed precoders’ structure and by applying the Hadamard’s inequality, the original problem is simplified from a matrix-valued problem to a scalar-valued one. However, the new scalar-valued problem is still nonconvex and we manage to convert it into two subproblems and solve it in an iterative fashion. By using the Karash–Kuhn–Tucker (KKT) conditions, we give out the closed-form solutions to the subprobelms. Simulation results demonstrate that the proposed design method converges rapidly and significantly outperforms the existing methods.     

Partial Relay Selection in Energy Harvesting Based NOMA Network with Imperfect CSI

The wireless body area network (WBAN) can effectively modify the health and lifestyle monitoring specifically where multiple body parameters are measured using biomedical sensor devices. However, power consumption and reliability are crucial issues in WBAN. Cooperative Communication usually prolongs the network lifetime of WBAN and allows reliable delivery of bio-medical packets. Hence, the main aim of this investigation is to propose a novel protocol Cooperative Energy efficient and Priority based Reliable routing protocol with Network coding (CEPRAN) to enhance the reliability and energy efficiency of WBAN using cooperative communication method. Firstly, to identify a relay node from the group of sensor nodes for data forwarding, an enhanced Cuckoo search optimization algorithm is proposed. Secondly, Cooperative Random Linear Network Coding approach is incorporated into the relay node to improve the packet transfer rate. CEPRAN is implemented in Ns-3 simulator and the experimental results prove that the proposed protocol outperforms the existing SIMPLE Protocol.

     

基于功率分配能量采集的全双工放大转发中继系统

针对三节点放大转发中继系统,研究了基于功率分配能量采集的全双工中继传输方案。在中继配置大规模天线的情况下,提出了三种天线选择方法,并通过合理的假设分别推导了三种天线选择方法的速率的近似闭合表达式,并设计了天线选择模式切换方案。基于三种不同的天线选择方法,该文分析了基于功率分配采集协议中的最优功率分配因子以及不同方案的算法复杂度。最后,通过蒙特卡洛仿真证明了闭合表达式的准确性,并基于发射功率和信道增益分析了三种方案的优缺点。其中在大发射功率的情况下,方案一的性能最优;在小发射功率的情况下,方案二的性能最优;在中等发射功率的情况下,折中的方案三的性能最优。      

Energy Efficiency Optimization in Relay-Assisted Networks with Energy Harvesting Relay Constraints

In this paper we consider data transmission in a decode-and-forward(DF)relay-assisted network in which the relay is energy harvesting(EH) powered while the base station(BS) is power-grid powered.Our purpose is to maximize the BS’s energy efficiency(EE) while making full use of the relay’s renewable energy and satisfying the specific average throughput requirements.In contrast to existing literature on energy harvesting system which only considers the radio transmission power,we take the static circuit power into account as well.We formulate the EE optimization problem and prove that the EE of the BS and relay are both quasiconvex in the instantaneous transmission rate.Then we divide the complex optimization problem into two point-to-point link level optimization parts and propose an energyefficient resource allocation(EERA) scheme in which power control and sleep mode management are jointly used.The simulation results demonstrate that EERA may achieve good energy saving effects.We also compare the EE of an energy harvesting relay system with a power-grid powered one and provide more insight into the EE problem of energy harvesting relay system.     

Secrecy Outage of a Cognitive Radio Network with Selection of Energy Harvesting Relay and Imperfect CSI

Wireless Personal Communications - This paper investigates the physical layer security of an underlay cognitive radio network with relay selection scheme under threats of an eavesdropper. We...     

能量收集全双工中继网络中的中继策略研究

本文针对双跳全双工多中继系统,研究了在中继节点能量受限情况下的中继选择方案。在该文中,中继工作方式为放大转发（Amplify-and-Forward, AF）,且中继通过收集源节点提供的能量来对源节点信息进行转发。整个通信过程分为两阶段,能量收集阶段与信息传输阶段,即采用的是时域分割方案。为了获得较好的性能与复杂度折中,本文分别研究了三种不同的中继选择策略,即最佳中继选择方案和两种次优中继选择方案。针对所提的三种方案,推导分析了其系统中断概率的理论值和下边界,以及系统的有效吞吐量。最后,利用蒙特卡洛仿真验证了理论分析的正确性,且仿真结果表明最佳中继选择方案的性能优于两种次优的中继选择方案,但其实现的复杂度高。