【作者】 李军；

【导师】 吴伟陵；

【作者基本信息】 北京邮电大学 ， 信号与信息处理， 2011， 博士

【摘要】 协作通信技术在原有网络拓扑结构基础上通过多用户协作,提升无线频谱资源利用率和系统功率效率。通过对无线通信系统频率、时间、空间等多维资源的有效复用,协作通信实现和支撑更高速率、更高带宽的无线传输,改善网络覆盖性能,已经成为B3G/4G移动通信的关键技术。本文分析了协作通信在不同系统模型和协作协议情况下的性能(SER误符号率、Outage中断概率和Throughput吞吐量)、协作伙伴选择、协作时机选择和功率分配,等问题。另外,研究了认知与协作技术相结合的问题,包括协作认知系统建模和性能分析。以优化多中继、放大转发协作(AF)通信系统误符号率(SER)性能为目的,我们在本文第三章提出一种多点协作最优功率分配(OPA)和协作伙伴选择方案。首先,分析多中继AF协作通信系统的理论SER。然后,推导出一种在高、低信噪比(SNR)情况下均较紧于SER理论值的下界。最后,以SER下界为代价函数,综合考虑系统整体统计信道增益,提出适用于多中继AF协作通信系统的最优功率分配与协作伙伴选择方案。理论分析和仿真结果表明,在系统总功率受限情况下,基于该方案的SER性能明显优于基于平均功率分配(EPA)方案。与现有算法相比,在低SNR情况下,基于该方案的SER下界较紧于理论值。第四章以优化多MIMO中继节点、译码转发(DF)、选择译码转发协作(SDF)和增强型SDF (ISDF)通信系统中断概率为目的,我们提出一种多点协作最优单MIMO中继选择方案,给出中断概率封闭表达式,并讨论了协作时机的问题。首先给出MIMO中继系统模型,并分析了不同中继节点情况下的中断概率。然后给出最优中继选择方案,在中继采用最大比合并接收和Beam-forming技术的情况下,推导出基于该方案的源-目的节点的互信息和中断概率,并证明了该方案的中断概率是普通SDF/ISDF协作系统中断概率的下界,其次,讨论自适应最优功率分配和协作时机问题,最后给出仿真结果和性能分析。第五章分成两部分。第一部分研究认知MIMO干扰系统中断概率、吞吐量和最优功率分配分析。重点推导了认知MIMO系统在理想、实际系统和平坦、瑞利衰落信道环境下的授权用户和认知用户的中断概率和吞吐量,给出相应的闭合数学表达式。在授权用户分组到达率随机到达,并且确保授权系统稳定的条件下,对授权、认知用户的功率分配和系统吞吐量进行了分析。提出适用于认知MIMO干扰系统的授权和认知用户的最优功率分配方案以及相应的最优吞吐量表达式。最后,通过仿真验证理论分析。仿真结果表明功率优化算法在确保授权用户稳定性前提下,同时提高了授权和认知用户系统吞吐量。为了对比分析,我们还给出了功率参数和信道参数相同情况下的,授权和认知系统均为SISO系统的仿真结果。第二部分研究协作通信与认知干扰无线通信系统结合问题,目的在于提高非对称认知干扰系统的性能。重点推导了放大转发(AF)协作模式的认知干扰系统在平坦、瑞利衰落信道环境下的授权用户和认知用户的中断概率和吞吐量,给出相应的闭合数学表达式。在随机授权用户分组到达率给定,并且确保授权系统稳定的条件下,对认知用户的功率分配和吞吐量进行了分析。提出认知协作干扰系统中的认知用户的最优功率分配算法,以及相应的授权和认知用户最优吞吐量。仿真分析表明协作技术和功率优化算法在确保授权系统稳定性前提下,能同时提高授权和认知系统性能。更多还原

【Abstract】 Cooperative communication is an emerging technology which is based on the existing network topology and has the ability to improve radio spectrum utilization together with system power efficiency through the multi-user collaboration. The technology implements and supports higher rates, higher bandwidth and wider network coverage through resources of the frequency, time, space, multi-dimensional effective multiplexing. Now the technology has become the key one of wireless communications B3G/4G.This paper analyzes the system performances and power allocation schemes under some kinds of model and protocols for cooperative communication systems. In addition, we also study the combination of cooperation and cognitive radio such as modeling and performance analyzing of cognitive and cooperative communication systems.The symbol error rate (SER) performance is analyzed for the optimization of amplify-and-forward (AF) multi-node cooperative communication systems in the third chapter. Firstly, theory SER is analyzed for the systems. Then, the corresponding low bound (LB) is derived, that will be nearing the theory SER between both low and high signal-to-noise ratio conditions. Finally, algorithms used in optimal power allocation (OPA) and partnership selection for the systems by exploring the LB as cost function are formulated. Theoretical analysis and simulation results show that the OPA outperforms traditional EPA in SER performance. Moreover, the LB will be more nearing the theory SER than existing algorithms especially under low SNR conditions.In the fourth chapter optimal relay and cooperation opportunity are analyzed for the outage performance optimization of decode-amplify-forward (DF), selective DF and incremental SDF (ISDF) in multi-node MIMO cooperative communication systems. Firstly, the system model for the proposed multi-node MIMO cooperative protocol is analyzed. Then, the optimal relay selection strategy (routing) is proposed. The mutual information and outage probability between source and destination nodes for the proposed scheme are formulated with the relays have the capability of maximum ratio combining (MRC) receiving and beam-forming transmitting. We proved that the outage performance for the proposed algorithm is the low bound for the general SDF/ISDF. Finally, we discussed the optimal power allocation and cooperation opportunity.The chapterⅤis divided into two sections. The first one analyzed the outage, throughput performance and power allocation for CR MIMO systems. The main contributions are the derivation of the outage and throughput closed-form expressions for licensed and cognitive users in both ideal and real cognitive MIMO flat Rayleigh fading environments. Under the condition of "transparent" from cognitive user to licensed user and random licensed user package arrivals, the paper analyzed the power allocation algorithm and the throughput then derived the optimal power allocation (OPA) algorithm for CR MIMO systems. Numerical results verified the theory analyses and the results show that the OPA algorithms maximize the maximum average throughput both for the licensed users and cognitive users while guarantees stability of the whole systems. For comparing, we also simulate SISO system under the same conditions.The second one studied the performance gain of asymmetry Cognitive Radio (CR) interference communication systems which is combined with amplify-and-forward (AF) cooperation technology. The main contributions are the derivation of outage and throughput closed-form expressions for licensed and cognitive users in cognitive cooperative communication systems under flat Rayleigh fading channel. Under the condition of "transparent" from Cognitive User (CU) to Licensed User (LU) and random LU package arrivals, the paper analyzed the power allocation algorithm and the throughput for the CU and derived the optimal power allocation (OPA) algorithm for cognitive cooperative communication systems. Simulation and analyzing show that the cooperation technology and OPA increase the overall system performance for both licensed and cognitive users while guarantee stability of the LU systems.更多还原