【作者】 曾令康；

【导师】 刘元安；

【作者基本信息】 北京邮电大学 ， 电磁场与微波技术， 2010， 博士

【摘要】 正交频分复用多址(OFDMA)系统已经成为第四代移动通信的主流多址技术,将其与自适应技术相结合,能充分利用无线信道中的频率分集和多用户分集,提升无线通信系统的频谱效率。博弈论是应用数学的重要分支,是研究具有竞争性质现象的数学理论和方法。将博弈论与无线通信系统相结合,能够产生新的研究思路和资源分配算法。本博士论文的主要贡献是基于博弈论为资源分配领域提供有价值的研究成果,包括提出创新性的概念、具有普遍意义的分析思路和多个资源分配算法。在比例公平研究领域,本论文首次将拍卖理论与比例公平准则相结合,采用最优化理论对基于比例公平准则的目标函数进行深入分析,详细讨论资源分配过程中隐含的经济学含义。结合拍卖理论给出基于优先级拍卖的理论框架,并据此提出基于优先级拍卖的资源调度方案。仿真结果表明,基于拍卖理论的资源分配算法能够满足上行OFDMA系统的比例公平调度要求,将比例公平因子设定为特定值时,所提方案还能实现纳什公平、最大-最小公平,表明了研究成果的普遍意义。在OFDMA系统的统一资源分配策略研究领域,本论文克服前人仅局限于某个特定目标函数进行设计算法的缺陷,采用最优化理论、合作博弈论和矩阵论寻找多个目标函数共性。与前人工作最大的不同是,本文重新定义了博弈过程中参与人的概念,提出多个具有创新性的概念、结论以及博弈思路,并据此提出统一资源分配方案——同时议价方案。仿真结果表明,统一资源分配方案不仅能在大多数情况下优于已知频谱效率最高的算法,实现纳什公平准则、最大-最小公平准则的资源调度需求,并能克服前人提出的实现纳什公平算法中的不收敛问题,表明统一资源分配策略研究的广泛意义。在基于部分信道状态信息的资源分配策略研究过程中,本论文主要针对快速衰落信道情形下的通信过程进行分析。依照中断理论中的信道建模过程,将信道分解成快速衰落和慢速衰落两部分,对信道在时间域采用二维建模。以最优化理论为分析工具,对发射功率限制进行放缩,并采用博弈论中的剩余函数对目标函数的最优解进行分析。在将上述分析过程推广到离散数据块情形,修正剩余函数的概念,设计出迭代剩余函数平衡算法,实现了非精确信道情形下的最优资源调度。剩余函数理论是本章研究的核心,为应用博弈论研究更复杂的中断问题做好了理论铺垫。在抑制多小区干扰的研究领域,本论文重点讨论小区间不交互信息前提下的分布式干扰抑制方案。首先分析单载波情形小区间干扰对系统总容量的影响规律,继而将研究结论推广到多载波情形。根据上述理论分析成果设计出分布式干扰抑制算法,使得每个小区独立负责本小区用户的资源调度过程,并且基站控制器负责收集各个小区的分配信息。通过采用适当的方法,基站控制器对各个子载波在各个扇区的使用情况进行判断、调整,以找到合适的纳什均衡点。仿真结果表明,本文提出的算法能够显著提升传统分布式方案的频谱效率和归一化频谱效率,为无线通信系统节省更多的功率。在认知无线电系统的频谱共享领域,本论文主要研究前人没有涉及的基于OFDM的认知无线电系统的频谱共享方案。通过采用干扰温度模型对主用户受到的干扰进行保护,并将每个认知无线电用户建模为一对收发机,本文依照主从系统之间的交互信息种类设计出三个分布式频谱共享方法。为应用经典博弈论,本文提出放缩博弈的概念以处理干扰温度限制,并论证了放缩博弈的收敛性、纳什均衡点的唯一性以及其与原博弈过程的等效性。仿真结果表明,所设计的三个分布式算法能依据交互信息种类实现认知用户的灵活频谱接入,有效解决基于OFDM的认知无线电系统的共道干扰限制问题。更多还原

【Abstract】 OFDMA has become the key transmission technologies for 4G mobile communication systems. Combining with adaptive technologies, frequency diversity and multiuser diversity can be effectively utilized to enhance the spectral efficiency of wireless communication systems. Game theory is a good mathematical tool for researching the competing behaviors and it has been widely used in wireless communication systems. Game theory can provide innovative research thought and algorithms to enhance the performance of wirless communication systems. Based on game theory, the main contribution of this doctoral dissertation is to provide significative research results for resource allocation field, including innovative concepts, universal analytical thought and resource allocation algorithms.In the field of proportional fairness, we introduce auction theory to research it for the first time. Based on optimization theory, the proportional fair objective function is investigated in detail, and the connotive economic meaning of the resource allocation process is also shown. Prirotiy-ranked bargaining framework is then proposed from auction theory. Simulation results show that the proposed scheme can realize proportional fairness criterion for uplink OFDMA system. When the proportional fairness index is set to proper value, the proposed scheme can realize the results of Nash fairness and max-min fairness, which embodies the universial meaning of the research work.Considering the fact that previous work in dynamic resource allocation field mainly focus on designing algorithms for a certain objective function, we target to propose a unified resource allocation framework in this dissertation. The mathematical tools include optimization theory, non-cooperative game theory and matrix theory. The most differences between previous works are:the concept of player is revised; several innovative concepts, theories and bargaining principle are proposed. Then the unified resource allocation scheme-simultaneously bargaining algorithm is proposed. Simulation results show that simultaneously bargaining algorithm can outperform the most efficient suboptimal schemes in most cases, and it can also realize Nash fairness and max-min fairness. In addition, the divergency of previous algorithm for Nash fairness is also overcome. These facts denote the universial meaning of the proposed unified resource allocation scheme.In the case of partial channel side information, we investigate the optimal resource allocation scheme for the case of fast fading. According to outage theory, the fading channel is modeled as two time-scale channel. Optimization theory is utilized to analyze the objective function, and surplus function in the economic field is utilized to characterize the optimal solution. By revising the concept of surplus function, the analyses are extended to discrete block case and optimial resource allocation algorithm is obtained for non-accurate fading channel. Surplus function is the key technology of this chapter’s research work and it can analyze more complex outage issues by combining with more game theoretical thoughts.In the field of multi-cell resource allocation, we dedicate to proposing distributed interference suppressing algorithm. Starting from single subcarrier case, the effect of inter-cell interference to the total capacity is discussed in detail, and then the analytical result is extended to multi-carrier case. The proposed distributed scheme allows each cell to allocate the resources independently, and the base station controller is responsible for gathering the allocation information. By checking out each subcarrier, the base station controller would evaluate each base station’s sharing behavior, and adjust the Nash equilibrium to enhance the performance. Simultion results show that the proposed scheme can greatly enhance conventional distributed scheme’s spectral efficiency and normalized spectral efficiency, and save transmission power for wireless communication system.In the field of cognitive radio, we mainly investigate the distributed spectrum sharing technologies. By modeling each cognitive radio user as a pair of transmitter and receiver, we set interference temperature limit for protecting the primary system and research distributed spectrum sharing behaviors based on the kinds of exchange information. In order to utilize the classic game theory, we propose the concept of relaxed game to deal with the interference temperature limit. The convergence issue, uniqueness of Nash equilibrium and the equivalence to original game are discussed in great detail. Simulation results show that the proposed three schemes can effectively deal with co-channel interference limit issues, and allow the cognitive radio system to flexibly utilize the unlicensed spectrum and work harmoniously with the primary system.更多还原