Asymptotic analysis of multi-branch two-way amplify-and-forward relaying in Nakagami-m fading with arbitrary fading parameter

Two-way relay networks have received lots of attention, thanks to its ability to overcome the loss in the spectral efficiency due to half-duplex transmission. Asymptotic performance analysis can provide valuable insights in- to practical system designs. However, this is a gap in two-way relay network. In this paper, the asymptotic performance is studied for multi-branch dual-hop two-way amplify-and-forward （AF） relaying networks in independently but not necessarily identically distributed （i.n.i.d.） Nakagami-m fading channels, with arbitrary m 〉 5. The approximate prob- ability density function （PDF） of the instantaneous dual-hop link power at high SNR region is derived. Then we present the asymptotic outage probability expression, and analyze the diversity order and coding gain. Simulations are per- formed to verify the tightness of the presented analysis at medium and high SNR regions.

PERFORMANCE ANALYSIS OF TWO-WAY AMPLIFY-AND-FORWARD RELAYING SYSTEM WITH MULTIPLE INTERFERERS AT THE RELAY

In this paper,we investigate the performance of the two-way Amplify-and-Forward(AF) relaying systems in an interference-limited Rayleigh fading environment.More specifically,assuming the presence of Rayleigh faded multiple interferers at the AF relay and noisy sources,an approximate closed-form expression for the Overall Outage Probability(OOP) and an integral expression for the average Symbol Error Probability(SEP) are derived.The analysis results are verified through com-parison with the Monte Carlo simulation results.

Outage Performance of Opportunistic Amplify-and-Forward Relaying over Asymmetric Fading Environments

This letter analyzes the outage probability of opportunistic amplify-and-forward relaying over asymmetric and independent but non-identically distributed (i.n.d) fading environments. The work investigates the scenarios where cooperative nodes are located at different geographical locations. As a result, the different signals are affected by different i.n.d fading channels, one may undergo Rician fading distribution and others may undergo Rayleigh fading distribution. In this letter, a lower bound of the outage probability for various asymmetric fading environments is derived at high SNR by applying the initial value theorem. The analytical model is validated through Monte-Carlo simulation results.

Parameter Optimization for Amplify-and-Forward Relaying Systems with Pilot Symbol Assisted Modulation Scheme

Cooperative diversity is a promising technology for future wireless networks. In this paper, we consider a cooperative communication system operating in an amplify-and-forward (AF) mode with a pilot symbol as-sisted modulation (PSAM) scheme. It is assumed that a linear minimum mean square estimator (LMMSE) is used for the channel estimation at the receiver. A simple and easy-to-evaluate asymptotical upper bound (AUB) of the symbol-error-rate (SER) is derived for uncoded AF cooperative communication systems with quadrature amplitude modulation (QAM) constellations. Based on the AUB, we propose a criterion for the parameter optimization in the PSAM scheme. We discuss how the pilot spacing and the length of the Wiener ?lter should be chosen under the constraint of a tradeoff between pilot overhead, estimation accuracy, and receiver complexity. We also formulate an power allocation problem for the considered system. It is shown that the power allocation problem can optimally be solved by means of a gradient search method. Numerical simulations are presented to verify the correctness of the theoretical results and to demonstrate the benefits of the parameter optimization.

Power control for two-way amplify-and-forward relaying over Rayleigh fading channels

We propose two novel power control policies for a two-way amplify-and-forward (AF) relaying system,in which each node (two sources and one relay) is assumed to operate under bothminimum and peak power constraints.Through the exploitation of instantaneous channel gains,the first policy can maximize the sum rate of the system.However,the instantaneous channel gains may be unavailable in a rapid time-varying system,where the first policy is inoperable.Consequently,a robust power control policy which requires only mean channel gains is proposed to maximize the upper bound of the average sum rate,and the properties of this policy are investigated.Simulation results show that,by comparison with the policy in which all the nodes use their peak transmit power,the proposed power control policies can provide considerable system performance improvement.Furthermore,the performance difference between the two proposed policies is negligible when the relay is close to one source.

Performance of two-way amplify-and-forward relaying with adaptive modulation over Nakagami-m fading channels

This paper investigates the performance of a two-way amplify-and-forward （AF） relay system with adaptive modulation over independent and non-identical Nakagami-m fading channels. The tight closed-form cumulative distribution function （CDF） expression of the instantaneous end-to-end signal-to-noise ratio （SNR） is provided. Further, approximate closed-form expression for the average spectral efficiency of the two-way AF system with adaptive modulation is obtained. Then, a tight lower bound of outage probability is derived. Finally, we use numerical simulations to verify the tightness of our analytical results.

Multi-user diversity analysis in MISO amplify-and-forward relaying network

This article analyzed multi-user diversity performance for multiple input single output （MISO） amplify-and-forward （AF） relaying network with selection combiner, and the closed-form outage probabilities for variable gain relaying and fixed gain relaying network are derived. Based on these results, diversity order is presented for variable gain relaying network. Simulation results validate the derived theoretical results, and the diversity order of variable gain relaying network with Nr available relays is K （Nt ＋ Nr） in K users＇ scenario, where Nt is the number of source transmitter antennas.

Beamforming Design for IRS-and-UAV-Aided Two-Way Amplify-and-Forward Relay Networks in Maritime IoT

In this paper,an intelligent reflecting surface(IRS)-and-unmanned aerial vehicle(UAV)-assisted two-way amplify-and-forward(AF)relay network in maritime Internet of Things(IoT)is proposed,where ship1(S1)and ship2(S2)can be viewed as data collecting centers.To enhance the message exchange rate between S1 and S2,a problem of maximizing minimum rate is cast,where the variables,namely AF relay beamforming matrix and IRS phase shifts of two time slots,need to be optimized.To achieve a maximum rate,a low-complexity alternately iterative(AI)scheme based on zero forcing and successive convex approximation(LC-ZF-SCA)algorithm is presented.To obtain a significant rate enhancement,a high-performance AI method based on one step,semidefinite programming and penalty SCA(ONSSDP-PSCA)is proposed.Simulation results show that by the proposed LC-ZF-SCA and ONS-SDP-PSCA methods,the rate of the IRS-and-UAV-assisted AF relay network surpass those of with random phase and only AF relay networks.Moreover,ONS-SDP-PSCA perform better than LC-ZF-SCA in aspect of rate.

Joint Linear Processing Design for Distributed Two-Way Amplify-and-Forward MIMO Relaying Networks

Linear transceiver designs are investigated for distributed two-way relaying networks,which aim at minimising the WeightedMean Square Error(WMSE) of data detections.The forwarding matrices at relays andequalization matrices at destinations are jointly optimised.To overcome the challenginglimitations introduced by individual powerconstraints,a Semi-Definite Relaxation(SDR)called element-wise relaxation is proposed,which can transform the original optimizationproblem into a standard convex optimizationproblem.In this research,two-way relaying isunderstood from a pure signal processing perspective which can potentially simplify thetheoretical analysis.Finally,simulation resultsare used for assessing the performance advantage of the proposed algorithm.

Optimization of Cooperative RelayingMolecular Communications for Nanomedical Applications

Recently,nano-systems based on molecular communications via diffusion(MCvD)have been implemented in a variety of nanomedical applications,most notably in targeted drug delivery system(TDDS)scenarios.Furthermore,because the MCvD is unreliable and there exists molecular noise and inter symbol interference(ISI),cooperative nano-relays can acquire the reliability for drug delivery to targeted diseased cells,especially if the separation distance between the nano transmitter and nano receiver is increased.In this work,we propose an approach for optimizing the performance of the nano system using cooperative molecular communications with a nano relay scheme,while accounting for blood flow effects in terms of drift velocity.The fractions of the molecular drug that should be allocated to the nano transmitter and nano relay positioning are computed using a collaborative optimization problem solved by theModified Central Force Optimization(MCFO)algorithm.Unlike the previous work,the probability of bit error is expressed in a closed-form expression.It is used as an objective function to determine the optimal velocity of the drug molecules and the detection threshold at the nano receiver.The simulation results show that the probability of bit error can be dramatically reduced by optimizing the drift velocity,detection threshold,location of the nano-relay in the proposed nano system,and molecular drug budget.

基于真实世界数据的注射泵临床使用有效性评价研究

目的基于真实世界数据(Real World Data,RWD)对注射泵的主要有效性评价功能进行研究,最大程度反映其临床实践中的真实性能表现,以建立科学有效的评价方法。方法选取本院重症医学科3种品牌(M、F、L)注射泵共计37台次作为研究对象,根据建立的临床使用评价指标,分别在5、25和50 mL/h 3种流速下,获得注射泵出第1滴液的时间和响应时间来测试注射泵快速启动的性能差异,计算流速平均值、相对示值误差和示值重复性来测试注射泵注射精度的性能差异;分别在5、10和15 mL/h 3种流速下,获得注射泵的流速波动下限和间歇时间来测试注射泵联机中继的性能差异。结果在快速启动功能方面,设定流速越大,注射泵出第1滴液的时间和响应时间越短,且在3种流速下,M品牌注射泵出第1滴液的时间和响应时间都最短(P<0.05)。在注射精度功能方面,在3种流速下,M和L品牌的流速控制性能和示值稳定性都显著优于F品牌(P<0.05)。在联机中继功能方面,人工模拟联机中继功能导致的流速波动下限和间歇时间差异显著(P<0.05),且设定流速越大,实时流速从下降到恢复设定值需要的间歇时间就越短。另外,M品牌的自动联机中继功能可有效解决前序泵与后序泵中继过程中产生的药物流量抖动或间断,但有瞬时流速上升,相对能够保证药物流量的稳定性和连续性。结论使用正确的基于RWD的注射泵临床使用评价方法不仅能够规范临床应用行为,还能够为注射泵的评价、准入/淘汰和集中采购/价格谈判提供数据支撑。

样本熵改进EEMD算法在继电器参数异常值处理中的应用

针对继电器参数中存在的异常值问题,文章提出了一种模态异常值处理模型。首先,依据继电器特点对集合经验模态分解(EEMD)算法中的参数进行灵敏性分析,确定优化参数;其次,针对EEMD分解中存在的模态混叠现象,采用样本熵和哈里斯鹰优化算法得到有效的模态分量;最后,分别采用拉依达准则及三次样条插值法对各模态异常数据进行识别及替换,将处理后的所有分量进行重构异常值,得到处理后的数据序列。继电器接触压降参数的实例分析结果表明,该模型具有良好的泛化能力,且能够有效地识别出潜在异常值。

Cognitive amplify-and-forward dual-hop relay networks over α-μ fading channels

This paper provides an analytic performance evaluation of dual-hop cognitive amplify-and-forward (AF) relaying networks over independent nonidentically distributed (i.n.i.d.) fading channels. Two different transmit power constraint strategies at the secondary network are proposed to investigate the performance of the secondary network. In the case of combined power constraint,the maximum tolerable interference power on the primary network and the maximum transmit power at the secondary network are considered. Closed-form lower bound and its asymptotic expression for the outage probability (OP) are achieved. Utilizing the above results,average symbol error probability (ABEP) at high signal-to-noise ratios (SNRs) are also derived. In order to further study the performance of dual-hop cognitive AF relaying networks,the Closed-form lower bounds and asymptotic expressions for OP with single power constraint of the tolerable interference on the primary network is also obtained. Both analytical and simulation are employed to validate the accuracy of the theoretical analysis. The results show that the secondary network obtains a better performance when higher power constraint is employed.

Power Allocation and Performance Analysis of the Collaborative NOMA Assisted Relaying Systems in 5G

Serving multiple cell-edge mobile terminals poses multifaceted challenges due to the increased transmission power and interferences, which could be overcome by relay communications. With the recent advancement of 5G technologies, non-orthogonal multiple access(NOMA) has been used at relay node to transmit multiple messages simultaneously to multiple cell-edge users. In this paper, a Collaborative NOMA Assisted Relaying(CNAR) system for 5G is proposed by enabling the collaboration of source-relay(S-R) and relay-destination(R-D) NOMA links. The relay node of the CNAR decodes the message for itself from S-R NOMA signal and transmits the remaining messages to the multiple cell-edge users in R-D link. A simplified-CNAR(S-CNAR) system is then developed to reduce the relay complexity. The outage probabilities for both systems are analyzed by considering outage behaviors in S-R and R-D links separately. To guarantee the data rate, the optimal power allocation among NOMA users is achieved by minimizing the outage probability. The ergodic sum capacity in high SNR regime is also approximated. Our mathematical analysis and simulation results show that CNAR system outperforms existing transmission strategies and S-CNAR reaches similar performance with much lower complexity.

Performance for Device-to-Device Communication with Three-Time-Slot Two-Way Amplify-and-Forward Relay Protocol

Multi-hop device-to-device(D2D) communication can significantly improve the system performance. This paper studied the outage performance of D2 D communication assisted by another D2 D user using three-timeslot two-way amplify-and-forward relaying protocol over Rayleigh fading channels. Considering the co-channel interference from cellular user at the D2 D node,the approximate expression for the overall outage probability was derived. Furthermore,a power allocation optimum method to minimize the outage probability was developed,and the closed form expression for the optimal power allocation coefficient at the relay was derived. Simulation results demonstrate accuracy of the derived outage probability expressions. Simulation results also demonstrate that the outage performance can be improved using the proposed optimal power allocation method.

城市电网10kV配电系统继电保护研究

城市电网建设质量与供配电活动的开展密切相关,其中10kV配电系统在电网系统中属于重要构成部分,要想保证人们正常生产活动有序开展要加强配电系统继电保护监控管理力度,为配电系统营造良好的运行环境。基于此,本文结合继电保护内容进行了简要概述,分析了城市电网10kV配电系统继电保护配置情况、存在问题和解决策略,以期为供配电管理提供参考。

基于量子加密技术的集中型馈线自动化在20kV电网中的应用研究

新时期,“用好电”成为人民追求美好生活新的意愿,传统单一的继电保护或者馈线自动化无法满足“供好电”要求。根据桐乡20kV配电网网架、设备以及故障特性等入手,减少分支线故障对主线影响,提升干线故障快速隔离及恢复。提出了支线或者环网柜出线保护与变电所出线开关保护极差配合,快速切除支线故障,主干线配置“三遥” 4G+量子开关或环网柜站所“三遥” DTU,大用户及大分支线配置“二遥”智能开关,主干线覆盖全自动FA助力配网秒级复电,保障电力系统安全稳定运行和社会经济高质量发展。

基于相控阵天线的空基多目标综合测控系统设计

为有效提升靶场空天地一体化的综合测控效能,切实满足高空高速目标以及低空多目标等全维度测控需求,提出基于相控阵天线的空基多目标综合测控系统方案。此系统构建了空天地一体化的立体测控架构,其主体由空基平台、机载测控分系统以及数据中继分系统组成,形成大容量测控信息中继传输的关键节点,具备对多目标全方位遥测信息的接收与转发能力,以及高码率测控信息的中继传输等功能,能够适应诸如高原、海上等复杂地域的快速机动布站要求,攻克了共形天线阵列设计、单元级全数字波束形成以及宽带数据中继通信等一系列关键技术难题,为空天武器靶场的测控工作提供至关重要的支撑与保障。

High-Performance Beamformer and Low-Complexity Detector for DF-Based Full-Duplex MIMO Relaying Networks

In this paper, we consider a full.duplex multiple.input multiple.output(MIMO) relaying network with the decode.and.forward(DF) protocol. Due to the full.duplex transmissions, the self.interference from the relay transmitter to the relay receiver degrades the system performance. We thus propose an iterative beamforming structure(IBS) to mitigate the self.interference. In this method, the receive beamforming at the relay is optimized to maximize the signal.to.interference.plus.noise.ratio(Max.SINR), while the transmit beamforming at the relay is optimized to maximize the signal.to.leakage.plusnoise.ratio(Max.SLNR). To further improve the performance, the receive and transmit beamforming matrices are optimized between Max.SINR and Max.SLNR in an iterative manner. Furthermore, in the presence of the residual self.interference, a low.complexity whitening.filter(WF) maximum likelihood(ML) detector is proposed. In this detector, a WF is designed to transform a colored interference.plus.noise to a white noise, while the singular value decomposition is used to convert coupled spatial subchannels to parallelindependent ones. From simulations, we find that the proposed IBS performs much better than the existing schemes. Also, the proposed low.complexity detector significantly reduces the complexity of the conventional ML(CML) detector from exponential time(an exponential function of the number of the source transmit antennas) to polynomial one while achieving a slightly better BER performance than the CML due to interference whitening.

基于电子执行模块场联信号异常关闭问题的解决方案

场联信号是车站2个场间安全高效行车作业的重要保证。将场联继电电路升级为电子执行模块后,应确保两场间敌对照查、邻场信号状态、接近预告等联锁信息的可靠传输。在场联信号设备升级工程分阶段实施过程中,存在已替换的电子执行模块与其余既有场联继电电路结合不匹配问题,导致场间作业过程中,因某些照查继电器短时落下造成出场信号异常关闭。结合实际案例,对现场数据和场联电路设计图进行分析,找出问题的直接原因。通过深入分析电子执行模块的处理逻辑,对比继电电路和电子执行模块在正负电转换过程中无电状态持续时间的差异性,提出相应的解决方案,包括优化电子执行模块处理逻辑、改进场联继电电路。该方案在具体工程项目中得到实际应用,取得较好的实施效果。