OFDM协作中继网络射频资源优化机制研究

发布时间：2018-05-15 08:18

本文选题：OFDM协作中继网络 + 射频资源分配　；参考：《武汉理工大学》2014年博士论文

【摘要】：正交频分复用（Orthogonal Frequency Division Multiplexing，OFDM）无线协作中继网络因其在提升网络容量域、增强端到端链路传输可靠性、扩大无线覆盖范围等方面的巨大优势以及在设计和部署上的灵活性，已受到学术界和产业界的广泛关注。在这种网络中，协作策略和射频资源分配是保证或提升其性能的两大关键研究点。另一方面，随着类型多样的高速高带宽新兴无线应用呈井喷式增长，无线频谱资源供给与用户服务需求之间的矛盾愈发加剧。再者，无线通信的能量消耗也逐渐变得不可忽略，构建绿色网络的需求也变得日益紧迫。因此，，如何提升无线网络的频谱效率、能量效率以及对各类应用服务的良好支持能力，将成为增强无线通信网络性能并缓解持续增长的无线应用需求压力的关键问题之一。鉴于此，本论文重点从频谱效率、能量效率和业务服务质量增强三个角度对OFDM无线协作中继网络射频资源优化相关理论与关键技术展开研究，以期获取高能谱效率和业务支持增强的射频资源优化分配方案，并为未来研究和部署以资源优化为核心的应用系统提供前期理论参考，从而为解决以上关键问题做出有益贡献。本文开展的主要研究工作如下：（1）综述分析并总结了无线协作中继网络相关研究工作。针对协作中继策略和射频资源优化分配两大关键研究点，以OFDM无线协作中继网络为重点，从协作策略、有专用中继节点辅助的单向协作中继网络资源分配、有专用中继节点辅助的双向协作中继网络资源分配、基于用户协作的中继网络资源分配以及系统设计几大方面，分类综述分析了与无线协作中继网络相关的国内外研究成果，并从网络场景因素和总体设计因素角度，分别比较与分析了已有典型方案的特点。在此基础上，对当前研究所存在的问题给出了几点总结和建议，并指出了网络编码、非完美信道状态信息（Channel State Information，CSI）和多目标优化设计在获取实用化高能谱效率射频资源优化方案上的重要性。（2）研究了单向多用户多中继OFDM网络异质业务增强及频谱效率优化问题。以单向多用户多中继OFDM系统为目标网络对象，综合考虑了实时业务流的最小速率需求、基于子载波配对的子载波分配、子载波级功率分配、子载波级中继-用户对选择等因素，以最大化非实时业务总传输速率为优化目标，研究了融入子载波配对技术的自适应射频资源分配方案，以期增强异质业务服务支持并优化频谱效率。针对总网络功率约束和独立节点功率约束两种网络配置场景，分别开发了相应的渐近最优资源分配算法，以期为不同的场景提供参考方案。仿真评估结果验证了所提算法在保证实时业务速率需求和系统频谱效率上的有效性，以及在依据流量需求和信道状态变化自适应调整射频资源分配方面的灵活性。（3）研究了融合动态网络编码的双向多中继OFDM网络频谱效率优化问题。针对基本的双向多中继OFDM系统，分析了网络编码在提升频谱效率和能量效率方面的优势，并对比分析了静态网络编码与动态网络编码的性能。以融合动态网络编码的双向多中继OFDM系统为目标网络，考虑含有概率性估计差错项的非完美CSI，阐述了一个最坏情形优化问题，并设计了一种具备对抗非完美CSI的鲁棒性射频资源优化策略。通过与拥有完美CSI假设的方案和运用静态网络编码的方案对比，仿真评估结果验证了所提算法在对抗非完美CSI方面的有效性，并揭示了动态网络编码在提升频谱效率上的优势。（4）研究了融合动态网络编码的双向多中继OFDM网络能量效率和业务体验质量（Quality of Experience，QoE）折衷优化。以融合动态网络编码的双向多中继OFDM系统为目标网络，面向能量效率和用户业务感知质量的多目标优化，研究了QoE与能量消耗的折衷优化问题。为获取QoE与能量的最佳折衷，提出了新的判据QEE（QoE-Energy），表征单位能量所产生的总QoE增益，并证明了QEE是QoE的准凹函数。QEE的准凹特性使得所阐述的以QEE为优化目标的射频资源分配问题成为准凹优化问题，且存在全局唯一最优化解。通过将所阐述的优化问题转化为一系列凸性可行性问题，提出了一种高效的低复杂度优化框架。在此优化框架下，分别针对解码-转发（Decode-and-Forward，DF）和计算-转发（Compute-and-Forward，CPF）两中继策略，开发了相应的渐近最优算法。仿真评估结果证实了所提算法在获取最优折衷点上的有效性。进一步地，在此研究基础上，通过对QoE和能量项引入加权因子，设计了一种QoE与能量折衷可控的射频资源优化策略，可实现由网络管理者可控可调的QoE-能量折衷。（5）研究了OFDM无线协作中继网络射频资源优化系统初步设计方案。基于GNU Radio/USRP开源认知软件无线电平台，研究了融合网络编码的OFDM协作中继网络资源优化系统试验床的初步设计方案，以期为未来实施系统部署工作提供指导和参考。具体地，给出了试验床的具体功能需求、硬件配置参数，并提出了一种模块化的节点软件架构和节点间交互流程。对具备频谱认知功能的OFDM物理层主要功能进了分析并提供了参考思路，包括：频谱帧听、多带滤波、单天线多包发送与多包接收和OFDM参数配置接口。提出了一种同步媒质接入控制（Medium Access Control，MAC）协议，给出了其帧结构、操作状态和协议流程设计参考方案，以期为未来部署和评估射频资源分配策略及网络编码等功能模块提供实施承载体。
[Abstract]:Orthogonal Frequency Division Multiplexing (OFDM) wireless cooperative relay network has received extensive attention in academic and industrial circles because of its great advantages in enhancing the network capacity domain, enhancing the reliability of end-to-end link transmission, expanding wireless coverage, and its flexibility in design and deployment. In the network, the collaboration strategy and radio frequency resource allocation are two key research points to guarantee or improve their performance. On the other hand, with the variety of high speed and high bandwidth emerging wireless applications in blowout, the contradiction between the supply of wireless spectrum resource and the demand of user service is becoming more and more serious. The demand for building a green network is becoming increasingly urgent. Therefore, how to improve the spectrum efficiency, energy efficiency and the ability to support all kinds of application services will become one of the key issues for enhancing the performance of wireless communication networks and alleviating the continued growth of the demand for line free applications. This paper focuses on the theory and key technology of radio frequency resource optimization in OFDM wireless cooperative relay network from three aspects: spectrum efficiency, energy efficiency and service quality enhancement, in order to obtain high energy spectral efficiency and business support enhanced radio frequency resource optimization, and to optimize the resources for future research and deployment. The core application system provides a theoretical reference for the early stage, thus making a useful contribution to solve the above key problems.
(1) the research work of wireless cooperative relay network is summarized and summarized. Aiming at the two key research points of cooperative relay strategy and optimal allocation of radio frequency resources, the OFDM wireless cooperative relay network is focused on, from the cooperative strategy, the network resource allocation is followed by the special relay node assisted unidirectional cooperation, and the special relay node is assisted. The resource allocation of two-way cooperative relay network, the resource allocation of the relay network and the system design based on the user collaboration, the research results about the wireless cooperative relay network are summarized and analyzed, and the characteristics of the existing typical schemes are compared and analyzed from the perspective of the network scene factors and the overall design factors. On this basis, some summaries and suggestions are given for the problems existing in the current research institute, and the importance of network coding, imperfect channel state information (Channel State Information, CSI) and multi-objective optimization design are pointed out in the acquisition of practical high energy spectral efficiency radio frequency resource optimization scheme.
(2) the problem of heterogeneous service enhancement and spectral efficiency optimization of unidirectional multiuser and multi relay OFDM networks is studied. One way multiuser multi relay OFDM system is used as the target network object, and the minimum rate requirement of real-time traffic is considered. Subcarrier allocation based on subcarrier pair, subcarrier level power allocation, subcarrier level relay - user selection In order to maximize the total transmission rate of non real time service as the optimization target, the adaptive radio frequency resource allocation scheme incorporating subcarrier pairing technology is studied to enhance the support of heterogeneous service service and optimize the spectrum efficiency. The phase of the two network configuration scenarios is developed for the total network power constraint and the independent node power rate constraint. An asymptotically optimal resource allocation algorithm is proposed to provide a reference scheme for different scenarios. The simulation results verify the effectiveness of the proposed algorithm in ensuring real-time service rate requirements and system spectrum efficiency, as well as flexibility in adaptive tuning of radio frequency resource allocation in accordance with flow requirements and channel state changes.
(3) the optimization of frequency spectrum efficiency of bidirectional multiple relay OFDM networks with dynamic network coding is studied. Based on the basic bidirectional multiple relay OFDM system, the advantages of network coding in enhancing spectrum efficiency and energy efficiency are analyzed, and the performance of static network coding and dynamic network coding is compared and analyzed in order to fuse dynamic network coding. The bidirectional multi relay OFDM system is the target network. Considering the imperfect CSI containing the probability estimation error term, this paper expounds a worst case optimization problem, and designs a robust radio frequency resource optimization strategy with anti imperfect CSI. It is compared with the scheme with the perfect CSI hypothesis and the scheme using the static network coding. The simulation results verify the effectiveness of the proposed algorithm in resisting imperfect CSI, and reveal the advantage of dynamic network coding in improving spectrum efficiency.
(4) the tradeoff optimization of energy efficiency and business experience quality (Quality of Experience, QoE) of the bidirectional multi relay OFDM network, which is fused with dynamic network coding, is studied. The multi-objective optimization of the bidirectional multi relay OFDM system which combines the dynamic network coding and the energy efficiency and the user's service perception quality is studied. The energy consumption and the energy consumption are studied. In order to obtain the best tradeoff between QoE and energy, a new criterion QEE (QoE-Energy) is proposed to characterize the total QoE gain generated by the unit energy, and it is proved that the quasi concave property of the QEE is a quasi concave function of the QoE, which makes the radio frequency resource allocation problem with the QEE as the optimization goal as a quasi concave optimization problem, and there is a whole problem. By converting the optimization problem to a series of convex feasibility problems, an efficient low complexity optimization framework is proposed. Under this optimization framework, the corresponding asymptotic best is developed for the two relay strategy of decoding forward (Decode-and-Forward, DF) and computing forwarding (Compute-and-Forward, CPF). The simulation evaluation results confirm the effectiveness of the proposed algorithm on obtaining the optimal tradeoff point. Further, on the basis of this study, a QoE and energy tradeoff controlled radio frequency resource optimization strategy is designed by introducing weighting factors to QoE and energy terms, which can achieve controllable and adjustable QoE- energy tradeoff from network managers.
(5) the preliminary design of the radio frequency resource optimization system of OFDM wireless cooperative relay network is studied. Based on the GNU Radio/USRP open source cognitive software radio platform, the preliminary design scheme of the OFDM cooperative relay network resource optimization system test bed is studied, in order to provide guidance and reference for the implementation of the system deployment in the future. Specifically, the specific functional requirements and hardware configuration parameters of the test bed are given, and a modular node software architecture and the interaction flow between nodes are proposed. The main functions of the OFDM physical layer with spectrum cognitive function are analyzed and some reference ideas are provided, including frequency spectrum frame listening, multi band filtering, single antenna multi packet transmission and multiple packets. The receiver and OFDM parameter configuration interface. A Medium Access Control (MAC) protocol is proposed. The frame structure, operation state and protocol flow design reference scheme are given in order to provide the implementation carrier for the future deployment and evaluation of radio frequency resource allocation strategy and network coding.

【学位授予单位】：武汉理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.53

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