论文标题:OFDMA系统的关键技术研究
Research on the Key Technique for OFDMA System
论文作者
论文导师 李式巨,论文学位 硕士,论文专业 信息与通信工程
论文单位 浙江大学,点击次数 267,论文页数 91页File Size4967K
2007-05-01论文网 http://www.lw23.com/lunwen_71197112/
Orthogonal Frequency Division Multiple Access (OFDMA); Frequency Offset Estimation; Adaptive Resource Allocation
未来的无线移动通信要求能够提供高速数据传输和宽带多媒体业务，正交频分多址技术(OFDMA)凭借其高效的频谱利用率以及优秀的抗多径干扰能力受到越来越多的关注，并被公认为下一代移动通信(4G)的关键技术之一。OFDMA是基于OFDM技术的新一代无线接入技术，它继承了所有OFDM技术的优点同时又具有自身不同的特点。本文通过对OFDM系统及OFDMA系统的介绍，分析了它们之所以能引起人们兴趣的诸多优点，根据OFDMA系统两大突出优点：频率利用率高和抗频率选择性衰落强，针对它们所引出的两个技术问题展开讨论，主要研究OFDMA上行链路频率同步中的频偏盲估计问题以及OFDMA系统下行链路的自适应资源分配问题。针对OFDMA系统上行链路的频偏盲估计，本文提出了两种基于不同子载波分配方式的频偏盲估计算法，在不需要任何训练序列和导频信号的帮助下完成频偏的盲估计。针对OFDMA系统下行链路的自适应资源分配问题，本文提出一种在系统总功率受限情况下，复杂度相对较低，且能保证一定服务质量的子载波和功率分步分配的自适应算法。
The wireless mobile communication in the future needs the ability to transfer the data with high speed and provide the broadband multimedia service. Because of its high spectrum efficiency and good immunity for the effects of frequency selective or multi-path channel propagation, orthogonal frequency division multiplexing access (OFDMA) has drawn much attention and became a hot spot of researching. OFDMA is a new wireless access technique based on orthogonal frequency division multiplexing (OFDM). It not only inherits all the advantages of OFDM, but also has its own characteristics. In this paper, we present the basic principle of OFDM and OFDMA, then analyze many of there advantages. According to the two uppermost advantages in OFDMA system, the high spectrum efficiency and immunity for frequency selective fading, we study the blind estimation of multi-user frequency offset in the OFDMA uplink and the adaptive resource allocation in the OFDMA downlink. For the blind estimation of frequency offset in OFDMA uplink, we propose two blind estimation algorithms based on different sub-carrier allocation strategies, which can estimate the frequency offset without the help of any pilot or training sequence. For the adaptive resource allocation in OFDMA downlink, we propose a QOS guaranteed adaptive sub-carrier and power allocation algorithm, which has low complexity and can fulfill the need of transmission rate or the proportional fairness of the users.
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