【作者】 汪德闯；

【导师】 张英海； 王卫东；

【作者基本信息】 北京邮电大学 ， 微电子与固体电子学， 2007， 硕士

【摘要】 随着移动通信技术的发展，人们对于宽带业务的需求日益增多，未来的移动通信系统(Beyond 3G、4G)必须能够提供更高的传输能力。在多种多址技术方案中，OFDMA具有最强的竞争力。OFDMA系统通过把高速串行的数据流变换到一组低速并行的子信道上发送，可以很好的解决宽带无线情况下出现的频率选择性衰落现象。能有效地对抗宽带无线接入系统中存在的符号间干扰，有效地利用信道的衰落特性和频率分集增益，提高系统容量。本文首先介绍了OFDMA系统的原理、子载波分配及其无线资源管理技术；然后深入研究了基于OFDMA系统的切换技术，并分析总结了目前OFDMA系统中切换算法的不足之处：OFDMA系统硬切换、软切换都存在着子载波切换不及时或者滞后的问题，OFDMA软切换还存在同址干扰(CCI)过大的问题。同时也存在着切换用户信道质量不是最佳的问题。在OFDMA系统的基础上，本文针对目前OFDMA切换算法的不足提出了新型的OFDMA切换算法：Level-up和子载波借用切换算法。Level-up算法旨在保证切换用户获得较好的信道质量，配合自适应调制技术从而获得系统吞吐量的提升。子载波借用算法除了具有上述优点，还可以充分利用OFDMA系统的信道资源，提高信道利用率，资源利用更加灵活。本人设计实现了OFDMA系统的仿真平台，并在此系统级仿真平台的基础上，通过仿真分析对本文提出的Level-up切换算法和对比算法的性能进行了评估和比较。仿真结果表明，新型的切换算法能够保证移动用户的信道质量，并带来系统吞吐量的提高，优化了OFDMA系统性能。更多还原

【Abstract】 With the development of mobile communications, people request more and more broad-band traffic. Mobile communication systems in future(such as Beyond 3G and 4G)must support higher transmitting ability. Among many division access technologies, OFDMA(Orthogonal Frequency Division Multiplex access) is best. OFDMA system transforms high-speed serial data streams to low-speed parallel data sub-channels and transmits them. It can well solve frequency-selective fading and effectively deal with ISI(inter symbol interference) in broad-band wireless condition, it can utilize channel fading characteristics and frequency diversity gain, and improve system’s capability.At first this text introduces OFDMA system theory sub-carrier allocation scheme and radio resource management(RRM) technologies; and then researches OFDMA system’s handover technology deeply, analyses and concludes the disadvantages of present handover algorithms.Based on OFDMA system, considering the disadvantages of present handover algorithms, this text puts forward new OFDMA handover algorithms: Level-up handover and sub-carrier borrowing handover. The former can ensure that handover user obtain better channel quality, cooperating with self-adaptive modulation technology, it can enhance OFDMA system’s throughput. The latter not only has the advantages above but aslo makes full use of OFDMA channel resource, improves channel uslizing effectivity and flexibility.After theoretic analysis, the author designs OFDMA system level simulating platform. By simulating, the author compares the Level-up handover algorithm with Proposed handover algorithm. Simulating result proves that new handover algorithm can guarantee the handover users’ sub-carrier channel quality, and improve OFDMA system throughput and optimize system performance.更多还原