协同中继选择与传输策略设计

发布时间：2018-07-01 18:41

本文选题：协同通信 + 协同中继　；参考：《重庆大学》2014年博士论文

【摘要】：“协同”的基本属性是参与协作的相关实体通过贡献、共享资源以实现某个共同目标，并获取额外收益。协同通信通过网元之间彼此共享信道资源构成虚拟MIMO（virtual multi-input multi-output）获得离散网元提供的空间分集增益或通过中继接力传输扩展覆盖范围、提高通信可靠性。协同通信的理论依据源于中继信道容量能提供比直传方式更高的信道容量这一重要结论，随后，协同通信的研究和应用范畴不断扩展，如在同构无线通信网络内部不同终端或不同技术协同，以提高系统性能；在异构无线通信网络之间相互协同，以获得“涌现”增益。虽然协同的思想为无线通信的发展和应用提供了一种新的实现途径，但协同通信策略对系统性能也会产生影响，如选择位于不同位置的网元参与协同，由于信道条件不同，协同能获得的性能增益也不同；在无线通信网络中，由于存在多个潜在的协同网元，如何从这些候选网元集合中快捷而有效的选取协同网元，是协同中继选择关注的重要内容。特别地，当多个用户并发通信时，如何选择协同网元对系统性能的提升最大，并考虑业务QoS（quality of service）需求、传输时延、性能增益以及公平性等将使问题更加复杂。此外，基于中继选择的协同资源分配能进一步优化网络性能，将中继选择与资源分配融合是协同策略研究的另一个重要内容。已有的协同中继选择和传输策略设计研究成果大多是针对单源协作应用场景下的系统性能和分集性能分析，而针对多源多中继、融合OFDM技术的中继选择以及双向中继传输等方面的中继策略和资源分配仍存在大量关键技术亟待深入分析研究。本文围绕协同通信中继选择和传输策略设计展开研究，重点探索OFDM下的中继策略、高密度网络的多用户中继策略、基于地理位置的中继策略以及不对称双向中继传输策略，主要内容和成果包括： 1）针对单源多中继单目标协同通信应用场景，研究协同传输与OFDM技术结合的协同中继选择与资源分配问题。为消除选择性OFDM中继传输中协同分集的实现受制于最差配对子载波信道质量的瓶颈，提出一种比特重加载的选择性OFDM协同中继方案。该方案仅选择单中继节点重传整个OFDM符号，通过在每跳执行自适应比特加载并采用最小最大法选择最佳中继节点，能获得选择协同的中断概率性能下界。理论分析了该中继方案的中断性能，并在固定传输速率和固定发送功率两种情形下给出了详细的中继选择和功率分配策略，通过仿真验证了所提方案的中断性能和端到端可达速率。 2）针对多用户协同MANET网络，依据随机方式或基于接收信噪比最大准则选择协作节点均不能通过用户间协作获得满分集，而采用固定顺序协作又忽略了信道状态因素，会降低协同增益。为了获得满分集，提出一种基于用户域协同和中继域协同的两阶段自治式协同中继选择算法，即将协同中继选择过程划分为源节点组中继选择阶段和空闲节点组中继选择阶段。在中继选择过程中，各节点独立决策是否中继和为谁中继，由于源节点组中继选择不能保证每个源节点都能找到中继，再利用空闲节点组中继选择为未找到中继的源节点选择中继。为了避免多个源节点选择同一中继节点，引入中继域的概念，空闲节点集合自主形成中继域，每个源节点在各自中继域内选取中继。通过与固定优先级传输机制，就包传输率和误符号率等性能指标进行的对比仿真测试，验证了算法的有效性。 3）针对多跳移动ad hoc网络，在已知节点位置信息的前提下，研究基于位置信息的能效最优中继选择策略。将协同通信技术引入移动ad hoc网络，根据节点位置信息进行下一跳节点选取和相应的中继选择。针对单用户多跳场景，设计了一种根据位置信息判断下一跳节点以及相应的中继节点选择方案。为了提高频谱效率，针对处于不同方位的两用户多跳场景，设计了一种能耗最小的中继选择方案。在下一跳节点选取中，利用无信标贪婪前传和无信标恢复前传分别在前向步进区域和后向步进区域进行下一跳节点选取；在中继选择中，根据节点位置信息，以系统能耗为优化目标，设计了一种基于位置的优先级判定和中继选取策略。 4）针对AF-OFDM双向中继系统，研究不对称通信需求约束下系统总能效优化策略。由于两个用户具有不同的通信速率要求，为速率要求高者分配更多的子载波；由于两个用户分配的子载波数不同，一部分子载波将工作在双向传输模式，而另一部分子载波将工作在单向传输模式。以系统能效为优化目标，构建联合中继传输模式选择、功率分配和比特加载的组合优化模型。针对该混合整数规划问题，提出一种结构近似优化算法。算法运行分为两阶段：第一阶段，固定子载波分配集合，优化单向中继传输和双向中继传输的功率分配，将原优化问题分解为两个子优化问题求解；第二阶段，利用子载波配对形成的线性结构搜索双向中继传输的最佳子载波数，避免穷举搜索造成的大运算量。
[Abstract]:The basic attribute of "synergy" is that the related entities involved in collaboration contribute to the sharing of resources to achieve a common goal and gain additional benefits. The cooperative communication is a virtual MIMO (virtual multi-input multi-output) sharing channel resources among the network elements to obtain the spatial diversity gain or through relay connection provided by the dispersed network element. The theoretical basis of cooperative communication is based on the capacity of the relay channel to provide an important conclusion that the channel capacity is higher than the direct transmission mode. Subsequently, the research and application category of cooperative communication is expanding, for example, the coordination of different terminals or different technologies within the isomorphic wireless communication network, High system performance; synergy between heterogeneous wireless communication networks to gain "emergent" gain.
Although the cooperative idea provides a new way for the development and application of wireless communication, the cooperative communication strategy will also affect the performance of the system. For example, the performance gain is different because of the different channel conditions. How to select the cooperative network element quickly and effectively from these candidate network elements is an important content of cooperative relay selection. In particular, how to select the cooperative network element to improve the performance of the system when multiple users are concurrently communicating, and consider the service QoS (quality of service) requirement, transmission delay and sex Energy gain and fairness will make the problem more complex. In addition, cooperative resource allocation based on relay selection can further optimize the performance of the network. The fusion of relay selection and resource allocation is another important part of the research of cooperative strategy.
The existing research results of cooperative relay selection and transmission strategy design are mostly aimed at system performance and diversity performance analysis in single source cooperative application scenarios. For multi source and multi relay, the relay selection and two-way relay transmission, such as relay selection and two-way relay transmission, still exist a large number of key technologies, and there are still a large number of key technologies. This paper focuses on the relay selection and transmission strategy design of cooperative communication, focusing on the relay strategy under OFDM, the multi user relay strategy of high density network, the relay strategy based on the geographic location and the asymmetric two-way relay transmission strategy. The main contents and results include:
1) aiming at the single source multi relay single target cooperative communication application scenario, the cooperative relay selection and resource allocation problem combined with the cooperative transmission and OFDM technology is studied. In order to eliminate the bottleneck in the quality of the worst matched sub carrier channel in the selective OFDM relay transmission, a selective OFDM collaboration with bit reloading is proposed. The scheme only chooses the single relay node to retransmit the whole OFDM symbol. By performing adaptive bit loading in each hop and selecting the best relay node with the minimum maximum method, this scheme can obtain the lower bounds of the probability performance of the selected cooperative. The interruption performance of the relay scheme is analyzed theoretically, and the fixed transmission rate and the fixed transmission power are fixed. In the two case, detailed relay selection and power allocation strategy are given, and the interrupt performance and end to end achievable rate of the proposed scheme are verified by simulation.
2) aiming at multi user cooperative MANET network, the cooperative nodes can not get full diversity through the cooperation between users according to the random mode or the maximum criterion based on the reception signal to noise ratio, and the cooperative gain will be reduced by using the fixed sequence cooperation and ignoring the channel state factors. In order to obtain full diversity, a kind of user domain collaboration and relay is proposed. The two phase autonomous cooperative relay selection algorithm of domain collaboration is divided into the source node group relay selection stage and the free node group relay selection stage. In the relay selection process, the nodes independently decide whether to relay and relay the relay, because the source node group relay selection cannot guarantee that each source node can be used. In order to avoid multiple source nodes select the same relay node, to avoid multiple source nodes to select the same relay node, the concept of the relay domain is introduced. The free node sets form the relay domain independently. Each source node selects the relay in the respective relay domain. The performance of the packet transmission rate and the symbol error rate are compared and simulated, and the effectiveness of the algorithm is verified.
3) aiming at the multi hop mobile ad hoc network, the optimal relay selection strategy based on location information is studied on the premise of the location information known. The cooperative communication technology is introduced into the mobile ad hoc network to select the next hop node and the corresponding relay selection according to the node location information. A kind of root is designed for the single user multi hop scene. According to the location information, the next hop node and the corresponding relay node selection scheme are determined. In order to improve the spectrum efficiency, a relay selection scheme is designed for the minimum energy consumption for the multi hop multi hop scene in different directions. In the next hop node selection, the forward and unbeacless forward passes are used in the forward step respectively. In the relay selection, a position based priority decision and relay selection strategy is designed in the relay selection, based on the location information of the node and the system energy consumption as the optimization goal.
4) aiming at the AF-OFDM two-way relay system, the total energy efficiency optimization strategy under the demand constraint of asymmetric communication is studied. Because two users have different communication rate requirements, more subcarriers are allocated for the higher rate required. Because the number of subcarriers allocated by the two users is different, some subcarriers will work in the bidirectional transmission mode, and the other is the other. A molecular carrier will work in a one-way transmission mode. Based on the system energy efficiency as the optimization target, a combined optimization model of joint relay transmission mode selection, power allocation and bit loading is constructed. A structure approximation optimization algorithm is proposed for the mixed integer programming problem. The algorithm runs into two stages: the first stage, fixed subcarrier division. In order to optimize the power allocation of one-way relay transmission and two-way relay transmission, the original optimization problem is decomposed into two sub optimization problems. In the second stage, the optimal subcarrier number of two-way relay transmission is searched by the linear structure formed by the subcarrier pair, so as to avoid the large amount of computation caused by the exhaustive search.
【学位授予单位】：重庆大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.5

【参考文献】