【作者】 黄蓉；

【导师】 冯春燕；

【作者基本信息】 北京邮电大学 ， 通信与信息系统， 2013， 博士

【摘要】 为应对无线数据业务的不断增长,未来无线网络需要更加密集的部署和复杂的传输技术以保证网络容量和覆盖,这将增加网络能量消耗和运营成本。另一方面,无线网络能耗的增加造成大量的温室气体排放,不利于环境保护和可持续发展。因此,寻找高能效的无线传输技术,降低网络能耗具有重大意义。协作中继传输技术作为一种能够有效提高系统容量、扩展网络覆盖的重要技术,目前已获得了广泛研究,并被各无线标准组织所采用。在中继网络中进行合理的资源管理和传输机制设计,可有效提高网络能量效率,为解决网络能耗问题,实现绿色通信提供新的契机。论文阐述了作者在国家重大科技专项“面向IMT-Advanced跨层优化技术”(2010zX03003-001-01)、中央高校基本科研业务费专项资金资助项目“无线中继网络能量高效传输技术研究”等项目中,对无线中继网络中高能效的资源管理和传输机制进行的深入探讨和相关研究成果。论文以单向中继网络和双向中继网络为研究对象,重点研究了能量高效的资源管理和传输机制,包括：功率分配和中继选择、多天线中继预编码技术、协作自动重传请求(Automatic Repeat reQuest, ARQ)技术,并提出相关算法,实现了中继网络的能效优化。主要研究工作和成果如下：(1)高能效的无线传输技术和相关理论综述与分析。重点总结了中继网络中高能效的中继选择和功率分配、多天线预编码转发以及中继协作ARQ传输技术的研究现状,并指出了目前研究存在的问题及挑战。(2)多中继网络中实现双向业务传输的高能效功率分配和中继选择机制研究。在单向和双向中继网络中,考虑双边用户业务服务质量(Quality of Service, QoS)需求的非对称性特点,首先以最小化系统加权能量效率为优化目标,利用KKT条件求解最优功率分配结果；然后结合跨层优化思想,进行媒体介入控制层(Medium Access Control, MAC)层传输模式和中继选择。所提机制可以有效平衡双向业务QoS需求的差异性,选择出同时满足双边业务QoS需求且降低网络能耗的最优中继。此外,探讨了跨层传输引入的信令交互开销和最优中继部署位置对网络能耗的影响,为实际高能效中继网络部署提供参考。(3)多天线中继网络联合功率分配和波束赋形机制研究。在多天线单向和双向中继网络中,首先将用户双向业务传输平均速率和误比特率需求转化为接收信号均方误差(Mean Square Error, MSE)约束条件,并在此基础上建立多天线中继网络能耗数学模型；然后通过将目标非凸优化问题转化为多个凸优化问题,并利用拉格朗日乘子法进行求解,给出各节点最优功率分配和波束赋形方案的闭式解。仿真结果表明,在单向和双向中继网络中,所提机制均可有效降低多天线中继网络的能耗,且收敛速度较快。为高能效的多天线中继网络应用提供理论依据。(4)中继协作ARQ能量效率研究。在单向中继网络中,提出将电路能耗和传输时延限制同时引入网络每比特传输所需能量建模中。通过穷举搜索法寻找最优传输速率和发送功率；并采用蒙特卡洛仿真验证最大重传次数对电路能耗和发送能耗折中关系,以及时延限制和总能耗折中关系的影响；在此基础上给出高能效的网络参数配置。在双向中继网络中,研究协作ARQ传输的能量效率和吞吐量之间的关系。将中继节点状态进行马尔科夫链建模；推导系统平均吞吐量和能耗；通过数值仿真分析两者之间的折中关系。研究结果表明,在协作ARQ传输过程中通过联合优化最大ARQ次数、传输速率及节点功率等参数,可在满足用户QoS需求条件下降低系统能耗。更多还原

【Abstract】 As the wireless communication data traffic increases rapidly, dense deployment and complex transmission technologies are required in future wireless networks, leading to increasing network energy consumption and operation cost for operators. On the other hand, energy consumption in wireless networks results in a large amount of greenhouse gas emission, which is harmful to environment protection and sustential development. Therefore, it is significant to investigate energy efficient wireless transmission technologies to reduce the network energy consumption. Cooperative relay transmission plays an important role in system capapbility enhancement and network coverage expansion. Recently, relaying has been widely studied and adopted by international standardization organizations. Reasonable resource management and transmission scheme design in the relay network can effectively improve the network energy efficiency, contribute to the solvement of the network energy consumption issues and provde new opportunity to realize green communications.This dissertation summarizes the research work the author accomplished on energy efficient resource management and transmission in relay networks. The research work is finacially supported by National Key Technology R&D Program of China:"IMT-Advanced Oriented Cross Layer Optimization Technologies"(2010ZX03003-001-01); The Fundamental Research Funds for the Central Universities:"Research on Energy Efficient Transmission Technology in the Relay Network".Taking one-way and two-way relay networks into account, the dissertation mainly focuses on energy efficient resource management and transmission in the network, including:relay selection and power allocation, multi-antenna relay precoding technology, cooperative ARQ, and develops related algorithms to acheive energy efficiency optimization. The main research work and achievements of this dissertation are as follows:(1) The related theory and wireless transmission technologies for enengy efficient transmission in the wireless network are analyzed. Existing research on energy efficient transmission issues in the relay network are summarized, including relay selection and power allocation, multi-antenna precoding and cooperative ARQ. The main research questions and challenges are also pointed out.(2) Research on energy efficient relay selection and power allocation scheme while satisfying QoS requirement of bidirectional users. Considering the asymmetric characteristic of bidirectional traffic in the one-way and two-way relay network, the weighted enenrgy efficiency of the system is first modeled as the objective and the optimal power allocation results are given using KKT conditions. Then, the optimal transmission mode and the best relay are selected in MAC layer, using cross layer theory. The proposed bidirectional traffic based transmission scheme can effectively reduce the network energy consumption while satisfying the QoS requirement for users. Furthermore, the impact of the signaling exchange overhead due to cross layer transmission and the optimal relay position on the network energy efficiency are discussed, which can be the reference for practical energy efficient relay network deployment.(3) Research on joint power allocation and beamforming transmission scheme in multi-antenna relay networks. In multi-antenna one-way and two-way relay networks, the average transmission data rate and bit error probablity requirement of birectional traffic are first converted into MSE limitations, and the energy consumption model is set up. By converting the non-convex objective problem into several convex sub-problems and employing Lagrange multiplier methods, the close form expressions of the power allocation and beamforming results for each node are given. Simulations demonstrate that in both one-way and two-way relay networks, the proposed power allocation and beamforming algorithm can improve the energy efficiency of the network effectively while guaranteeing the speed of convergence. The research can provide theory basis for the usage of energy efficiency multi-antenna relay networks.(4) Research on the energy efficiency of cooperative ARQ transmission. In the one-way relay network, the redundant circuit energy consumption and latency caused by retransmissions are introduced into the energy consumption per bit transmitted model. Adopting exhaustive search methods, the optimal instantaneous transmission rate and power are found. The impact of the maximum retransmission number on the tradeoff between circuit energy and tranmission energy consumption, the tradeoff between latency limitation and system energy consumption, are demonstrated through Monte Carlo simulation. Based on the results, energy efficient transmission parameters are discussed. In the two-way relay network, the relationship between system energy efficiency and throughput of ARQ transmission is investigated. By modeling the state transfer process of the relay as a Markov chain and analyzing the transition probability between different states, the throughput and the energy consumption of the network are derived. The tradeoff between the throughput and energy efficiency are discussed using the results of numerical simulations. It is shown that in cooperative ARQ transmission, the energy consumption can be reduce by jointly optimizing the parameters, such as the maximum ARQ retransmission number, transmission data rate and transmit power, etc.更多还原