【作者】 王凯蓉；

【导师】 田斌；

【作者基本信息】 西安电子科技大学 ， 通信与信息系统， 2010， 硕士

【摘要】 MIMO技术在提高无线通信系统容量和可靠性上具有的巨大优势,使其成为未来移动通信普遍采用的技术之一。采用时分双工(TDD)的MIMO系统可以利用上下行信道的互易性,使得基站能够直接根据估计得到的上行信道状态信息进行下行发端预处理,而不需要额外的反馈开销。但是信道的时变特性将导致信道互易性的损失,使TDD系统的优势无法发挥。论文分析了信道时变对TDD-MIMO通信系统信道互易性的影响,在此基础上提出了相应的补偿方法。本文主要内容如下:1.分析了时变空间信道模型NE-3GPP SCM(newly extended-3GPP spatial channel model),及TDD系统的帧结构,并在此基础上通过仿真讨论了时变信道的特性;2.基于奇异值分解(SVD)方法,分别推导了信道时不变和信道时变情况下的系统容量公式,并进行了仿真验证,仿真结果表明,采用预编码方式时,信道时变严重影响了系统误码率和容量性能,信道互易性损失;3.为了补偿时变信道引起的信道互易性的损失,给出了基于信道预测的补偿方法,仿真结果表明,该方法能够补偿信道时变造成的TDD-MIMO信道互易性的损失,有效提高TDD-MIMO误码率性能和容量。更多还原

【Abstract】 With an enormous advantage of achieving high system capacity, MIMO technique has been one of the widely used techniques in future wireless communication systems. By using channel reciprocity in time division duplex(TDD) MIMO systems, the base station(BS) can preprocess transmitting data according to the channel state information (CSI) obtained by uplink measurement without additional feedback overhead. But time-varying channel leads to the loss of channel reciprocity, which will invalidate the advantage of TDD systems.This thesis analyzes the impact of time-varying channel on channel reciprocity in TDD-MIMO communication systems. And then method compensating channel reciprocity is proposed. The main contributions are as follows:1. The time-varying channel model NE-3GPP SCM (newly extended-3GPP spatial channel model) and the frame structure applicable to TDD systems are discussed, and the characteristics of time-varying channel are analyzed.2. According to the SVD-based systems, the capacities over time-invariant channel and time-varying channel are derived respectively. Simulation results show that the bit error rate(BER) performance and system capacity are severely degraded over time-varying channel,the channel reciprocity is destroyed.3. A compensation method is given to compensate the loss of channel reciprocity due to time-varying channel. Simulation results show that, using channel prediction in BS can significantly improves the BER performance and the system capacity. Thus, the channel reciprocity is compensated effectively.更多还原