【作者】 杨乐；

【导师】 李维英；

【作者基本信息】 西安电子科技大学 ， 军事通信学， 2008， 硕士

【摘要】 本文主要研究了OFDMA及认知OFDM系统中的无线资源管理技术。文中首先介绍了OFDM及认知无线电的基本原理;其次,对OFDM系统中无线资源分配技术进行了详细的研究,分析了Jang, Yin, Rhee, Shen, Wong等几种经典的子载波-比特-功率分配算法;最后,介绍了一种基于公平约束下的改进的整数比特资源分配算法,该改进的整数比特资源分配算法能有效提高系统吞吐量。在此基础上,给出话音业务与数据业务共存系统模型下的多业务资源优化分配方案。在该方案中,首先,对于时间敏感业务而言,系统优先为其分配资源以保证其对时延的要求,通过为其分配子载波簇以降低所需反馈信息量,通过增加子载波簇上的功率来降低其占用的频带宽度;其次,将剩余资源灵活地分配给数据业务,实现子载波-功率-整数比特分配,同时着重考虑整比特分配后所产生的剩余功率重分配问题,从而进一步提高系统的吞吐量。仿真结果表明,本文多业务资源优化算法相对于固定载波分配算法和最大吞吐量算法达到较好的频谱利用率和较小的掉线率。最后,研究了一种认知OFDM系统中认知用户资源分配方案。在该方案中,通过功率上限的控制,在不干扰授权用户通信的前提下进行子载波-功率分配。仿真结果表明,在满足系统服务质量(QoS)要求的前提下,本文认知用户资源分配算法相对于自适应资源分配算法使频谱资源的利用率有较大提高。更多还原

【Abstract】 Radio Resource Management (RRM) in adaptive OFDMA networks and OFDM based Cognitive Radio Systems is considered in the thesis.Firstly, the basic principles of OFDM and Cognitive Radio are introduced. Secondly, RRM in OFDM Systems is analyzed particularly in this paper. Performances of some typical subcarrier-bit-power allocation algorithms, including Jang algorithm, Yin, Rhee, Shen and Wong algorithm, are analyzed. Thirdly, under the constraints of integer bit allocation and the proportionnatily among the different users’throughput, a subcarrier- power-integer bits allocation scheme is analyzed. This allocation scheme can maximized the throughput of OFDMA Systems.Meanwhile, the scheme of allocating OFDMA radio resource to multiple service,i.e., time sensitive services and time insensitive services, with different Quality of Service (QoS) , is designed in detail. In this scheme, the time sensitive services, with high priority to get the necessary resources to meet their time delay requirements, gain subcarrier clusters to lower the feedbacks and a little more power on each subcarrier cluster to reduce the occupancy of the bandwidth. Then the remaining resources after the first step are adaptively assigned to time insensitive services to realize the subcarrier-power-integer bits allocation to maximize the throughput of the time insensitive services, with the help of remaining power reallocation. Simulation results indicated that drop rate of our method can be decreased greatly compared with the Maximum throughput scheme and Fixed allocation schmem; meanwhile the throughput of our method is simaliar to that of the Maximum throughput scheme and greater than the Fixed allocation schmem.Finally for OFDMA-based cognitive radio system, the radio resource management for cognitive users and primary users are considered with the constraint that no interferences are induced to the primary users by the cognitive users. The simulations verify the performance of the proposed scheme, and the spectrum efficiency of the cognitive system is increased greatly.更多还原