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采用相干检测的物理层网络编码系统的误比特性能与载波同步精度密切相关,收发双方的载波同步误差将引起系统性能恶化。本文研究了残余载波同步误差对采用相同星座和正交星座BPSK信号的两种物理层网络编码双向中继系统误比特性能的影响。首先基于最大似然准则推导了存在残余载波同步误差时中继节点及源节点处接收信号的判决区域,然后运用Craig极坐标法分析了系统多址接入、广播阶段及总的端到端误比特性能,得出了精确的误比特率表达式,文中的分析方法可推广到采用其他调制方式的物理层网络编码系统。计算机仿真表明:文中的理论分析与仿真结果完全吻合,所推导的理论公式可以效地评估BPSK调制物理层网络编码系统的误比特性能;正交星座系统对载波同步误差更为敏感,相同的同步误差对正交星座系统的性能恶化更为严重。 相似文献
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《无线电通信技术》2017,(6):1-4
针对无线中继网络中物理层网络编码技术的应用,分析验证了其所带来可观的吞吐量性能提升。总结了当前物理层网络编码技术的相关研究方向,归纳了通信理论研究、信息理论研究和网络理论研究三个方面。介绍了物理层网络编码的关键技术,对物理层网络编码技术在实际信道条件下的性能分析及改进、采用高阶调制时的检测模糊及改进、基于嵌套格码的计算-转发策略和结合缓冲中继协议设计进行了深入探讨。以期放宽物理层网络编码对信道模型的限制,拓展其适用条件,同时在保障通信过程可靠性的前提下充分发挥该技术对通信有效性的提升,从而推进物理层网络编码技术在实际无线中继通信系统中的应用。 相似文献
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双向中继信道中物理层网络编码的性能分析 总被引:1,自引:0,他引:1
针对双向中继信道,文章研究采用放大转发协议的物理层网络编码的性能.在考虑直传链路下,给出了3时隙网络编码的可达速率.在高信噪比条件下,推导了 3时隙物理层网络编码方案和2时隙物理层网络编码方案的中断概率近似表达式.通过仿真,验证了理论分析结果.同时,对3时隙物理层网络编码方案中继节点的功率分配因子进行了优化,在中继节点处于不同位置下分节点等功率和不同功率对不同方案进行了最大和速率的仿真,结果表明3时隙物理层网络编码可以利用网络的非对称性提高性能. 相似文献
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物理层网络编码机会中继及中断性能分析 总被引:2,自引:1,他引:1
该文研究了频率非选择性瑞利衰落信道中的物理层网络编码系统容量问题。基于放大转发机制提出了一种基于最大最小互信息准则的机会中继策略。在瑞利衰落信道环境下,从双向通信的角度,通过理论分析得出其中断概率解析式,同时推导了理想物理层网络编码和传统直接传输系统的中断概率解析式。通过理论分析,发现在某些节点发射功率条件下,系统中断概率将完全取决于单向链路。在此基础上完成了数值仿真实验,结果表明所提策略的中断性能与理想物理层网络编码和传统直接传输相比有了显著的提高。 相似文献
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在实际的移动通信环境中,信道的状态复杂多变,该文针对双向中继信道的非对称性,提出采用分层调制方式的物理层网络编码方案。首先构建源节点、中继节点均采用分层(2/4-PSK)调制的双向中继通信系统模型;其次给出了中继节点的物理层网络编码解调及映射规则,推导出加性高斯白噪声下中继误比特率及端到端误比特率理论计算公式;最后仿真验证了理论分析结果。与采用传统QPSK调制技术的物理层网络编码相比,该方案利用分层调制的技术优势,确保较优信道的高速率传输,也兼顾了较差信道的传输可靠性。 相似文献
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空间调制(Spatial Modulation)通过利用天线索引承载数据信息,可以提升复用增益,实现更高速传输。利用这一特性,可针对协同多址接入信道模型设计一种基于空间调制的物理层网络编码方案。在协同节点,将其中一个源信息映射成传统调制符号,而将另一个源信息映射到协同节点的天线序号上。在目的节点,通过最大似然检测,判决接收到的传统调制符号和发射天线序号,分别恢复两个源节点发送的信息。研究结果表明,由于两个源信息载体相互独立,基于空间调制的多址接入方案可以获得优于传统方案的容量区域。仿真结果表明,在高信噪比条件下,系统和速率近提高1倍,同时两路信息误码性能均较好。此外,考虑到实际系统中使用的并非理想的高斯信源,文中分析均基于有限字符集展开。 相似文献
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In this paper,a network scenario of two-way relaying over orthogonal frequency division multiplexing(OFDM) is considered,in which two nodes intend to exchange the information via a relay using physical-layer network coding(PLNC).Assuming that the full channel knowledge is available,an optimization problem,which maximizes the achievable sum rate under a sum-power constraint,is investigated.It is shown that the optimization problem is non-convex,which is difficult to find the global optimum solution in terms of the computational complexity.In consequence,a low-complexity optimal power allocation scheme is proposed for practice implementation.A link capacity diagram is first employed for power allocation on each subcarrier.Subsequently,an equivalent relaxed optimization problem and Karush-Kuhn-Tucker(KKT) conditions are developed for power allocation among each subcarrier.Simulation results demonstrate that the substantial capacity gains are achieved by implementing the proposed schemes efficiently with a low-complexity computational effort. 相似文献
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The capacity issue of a denoise-and-forward(DNF) protocol was focused on based PNC system of frequency non-selective Rayleigh fading channel.First,the total sum-rate of the system was derived.With the derived sum-rate expression,two policies maximizing the system sum-rate are proposed.On this basis,a novel adaptive diversity scheme was proposed.Closed-form expressions of the system outage probability with the new proposed scheme as well as the amplify-and-forward (AF) based PNC system and the conventional direct transmission were derived over frequency-nonselective Rayleigh fading channels.Simulation experiments are conducted and the results show that the outage performance of the system can be im-proved significantly compared to the AF based PNC system and the conventional direct transmission scheme. 相似文献
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This article considers the two-way multiple-input multiple-output (MIMO) relaying channels with multiple users, in which multiple users are served simultaneously by the base station (BS) with the assistance of the relay. The transmission consists of only two phases, doubling the system throughout over traditional one-way half-duplex transmission. A zero-forcing dirty paper coding (ZFDPC) aided physical-layer network coding (PNC) scheme is proposed in this article and the achievable capacity of the ZFDPC aided PNC scheme is derived. Simulation results show that the proposed scheme outperforms the previous decode-and-forward (DF) and zero-forcing beamforming (ZFBF) aided PNC scheme due to more degrees of freedoms and the advantage of PNC. Moreover, we analyze the effect of the imperfect channel state information (CSI) from RS to users at BS side to show the robustness of the proposed ZFDPC aided PNC scheme. 相似文献
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Suman Bhunia Iti Saha Misra Salil K. Sanyal Anindita Kundu 《International Journal of Communication Systems》2011,24(8):1087-1104
WiMAX—the Worldwide Interoperability for Microwave Access is a promising technology for offering high‐speed data, video and multimedia services over mobile platform evolving toward all IP networks. The increasing demand of WiMAX for VoIP and high‐speed multimedia is due to the simplicity of installation and cost reduction compared with the traditional wired DSL cable. The challenges to service providers lie with the Quality of Service (QoS) under varying fading environment while at the same time maximizing for resource utilization. In this paper, a rigorous and comprehensive performance study of mobile WiMAX has been made with respect to adaptive modulation and coding techniques considering the variation in the speed of the mobile, path‐loss, scheduling services and application type for comparing with the fixed type of modulations. The OPNET 14.5.A modeler for WiMAX platform has been used as simulator for adaptation at the physical layer of the transmission in WiMAX OFDMA structure. Observation reveals that dynamic adaptation of modulation and coding schemes based on channel condition enables better QoS while consuming low overall bandwidth of the system. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Combining network coding and compressed sensing for error correction in wireless sensor networks 下载免费PDF全文
Siguang Chen Meng Wu Kun Wang Zhixin Sun Weifeng Lu 《International Journal of Communication Systems》2015,28(7):1303-1315
As the spatial and temporal correlations of sensor readings are common in wireless sensor networks, motivated by these features and the drawbacks of network coding (NC), we introduce compressed sensing (CS) into NC scheme and construct a cooperating coding mechanism, which performs over different data fields with a compatible transformation measure for the combination of NC and CS. This cooperating coding scheme can reduce the amount of redundant information transmission significantly, because the temporal and spatial correlations are explored fully. Meanwhile, the erasures and errors are considered simultaneously in relay transmission process; a NC decoding for error control is proposed to correct the erasures and errors. Although the decoding error of NC is existent, this error can be further reduced by the reconstruction process of CS; as a result, the relative recovery error is small enough in the sink. Finally, the reliability and performance analyses confirm that the proposed cooperating coding scheme obtains considerable compression gain as compared with conventional coding scheme of NC and transmits information reliably with high recovery precision. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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In order to exchange information among k users using the technology of physical-layer network coding in the multiple input multiple output Y two-way relay channels,the GSA-GSA scheme was proposed,using the technology of general signal alignment during the uplink and the downlink.The signals were exchanged between every source node align in a transformed subspace,rather than the direct subspace.This was realized by jointly designing the precoding matrices at all source nodes and the processing matrix at the relay.The constraints of the number of sending and receiving antennas and the sum rate of proposed scheme were analyzed.In simulation,it can figure out that the proposed scheme needs fewer antennas in the whole system and can improve the achievable system sum rate under the same SNR and degrees of freedom. 相似文献
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In this paper, we study the performance of physical-layer network coding in asy- mmetric two-way relay channels using four different cases having different poor channels: phase asymmetry, downlink asymmetry, uplink asymmetry and node asymmetry. The decision and mapping rule for symmetric and asymmetric cases are studied. The performance in terms of bit error rate for each case will be studied and analysed by computer simulation. Analytical and simulation results show that uplink asymmetry is the worst case; intra-phase asymmetry and unreliable uplink channels will more severely affect the performance degradation, which is caused by channel asymmetry. 相似文献