【作者】 贾楠；

【导师】 吴文礼；

【作者基本信息】 北京邮电大学 ， 信号与信息处理， 2008， 硕士

【摘要】 移动通信系统应用需求迅速增长,要求在更复杂的通信环境中提供给更多的用户以更好的通信服务质量,对通信技术的发展提出更高的要求。正交频分复用(OFDM)技术可以有效的抵抗多径衰落,具有非常高的频带利用率,可以很好的满足通信技术进一步发展的要求。对OFDM系统来说,需要进行相干解调,而进行相干解调需要知道信道的信息,因此信道估计具有重要的意义。对OFDM传输系统中的关键技术信道估计技术进行研究。针对OFDM传输系统介绍了信道估计技术。信道估计技术分为非盲估计与盲估计两类,本文主要研究非盲信道估计中的数据辅助信道估计,首先介绍辅助数据分布需满足的一般原则,之后介绍三种具体的辅助数据信道估计算法,包括LS信道估计、变换域信道估计与LMMSE信道估计。从实际应用的角度出发,在WiMAX标准与LTE标准单天线系统中仿真实现LS信道估计与变换域、线性插值方法。WiMAX下行链路仿真实现LS信道估计与线性插值法,分析权重因子对信道估计结果的影响;LTE下行链路中仿真实现在LS信道估计基础上同时使用变换域插值与线性插值,以及在LS估计基础上仅使用线性插值,比较这两种方式的系统性能差异;LTE上行链路中分析不同运动速率条件下LS信道估计的系统性能差异;比较LTE上行、下行链路LS信道估计系统性能差异,并对其原因进行理论分析;对MIMO-OFDM系统辅助数据分布进行分析并证明一种辅助数据取值可达到最佳信道估计条件。更多还原

【Abstract】 With the development of the mobile telecommunication implementation, it is required that the telecommunication systems supply better communication service quality to more customers even in complicated environment. The communication technology development is highly required. Orthogonal frequency division multiplexing modulation technology, which effectively resists multi-path fading interference and being with high spectrum efficiency, perfectly satisfy the requirement of the telecommunication development. The coherent demodulation is used in the OFDM system and in this case the channel information is needed so the channel estimation technique is of great significance.The channel estimation schemes are studied. The channel estimation schemes for OFDM based system are introduced in detail. Channel estimation technique for OFDM based systems can be grouped into two main categories: blind and non-blind. The non-blind channel estimation with aided data is studied. The basic principles of the aided data location are introduced, and three kinds of channel estimation schemes, the Least Squares (LS) channel estimation technology, transform domain technology and Linear Minimum Mean Square Error (LMMSE) channel estimation technology, are described.From the point of view of practical implementation, the simulation of LS technology, transform channel estimation and linear interpolation technology are based on WiMAX and LTE single-input single-output systems. In the WiMAX downlink system the comparison of effect of the two kinds of aided data is simulated, and the weight factor’s effect on the system performance is analysed. In the LTE downlink system the effect of the transform estimation with the LS estimation scheme to the system performance compaired with the linear interpolation with LS scheme is simulated and analysed. In the LTE uplink system the resistance of the LS estimation scheme against moving speed is simulated. And the performance difference of the LTE uplink and downlink system respectively with LS estimation scheme and ideal estimation scheme is analyzed both in simulation result and in theory. In the end a kind of aided data value is proved theoretically which can supply the best condition for channel estimation.更多还原