节点文献
WCDMA系统中MIMO预编码的研究
【作者】 韩玉；
【导师】 王建国；
【作者基本信息】 电子科技大学 ， 信号与信息处理， 2010， 硕士
【摘要】 支持MIMO技术的WCDMA HSPA+是3G到4G的过渡阶段,这一阶段通过在收发端引入多天线技术,将发射端信源输出的串行码转换成多路并行的子码流,在同一频段通过不同的发射天线同时发送。MIMO这个4G系统特有技术的引用,使频率资源得到重复利用,从而在原有的频带内实现信息高速率的传输。支持MIMO技术的WCDMA系统,虽然得益于多天线提供高速率传输,但也在多径干扰的基础上引入更多的码间干扰。码间干扰产生的根本原因是带宽受限和时延扩展,传统的解决方法是在接收端进行均衡处理。本文通过列举几个常用的均衡方法研究了均衡算法的复杂度,如果在下行链路中,均衡算法的复杂度无法消减的话,作为接收端的移动通信设备使用接收滤波器就必须加大体积,以便携为特点的移动接收机是无法做到的。预编码技术就以简化接收端信号处理的目的逐渐发展起来。预编码有线性和非线性之分:线性预编码得益于其实现简单的特点,成为无线移动通信系统最常采用的方法;非线性预编码虽然可以更接近信道容量上限,但其实现的复杂度过大。本文通过研究SVD预编码和通信协议中采用的基于码本的预编码,总结了线性预编码的设计标准,并研究了将码本的方式应用于SVD预编码中。本文还提出了一种综合的相位预编码,其设计思想是在接收端用实、虚部点乘法检测两信道中相互正交的信号,预编码矩阵需要做到消除信道的相位干扰,并且将两天线上的信号正交化。相比几种常用的预编码方法,其差别是并没有彻底改善有效信道的状态,而是以简化信号检测为目的。
【Abstract】 WCDMA HSPA+ which supports MIMO is transition phase from 3G to 4G. In this period, through introducing MIMO, it transforms original serial code to parallel multichannel sub-streams, and scents them from different antennas in the same frequency band. MIMO which is the peculiarly technology in 4G makes frequency resource reuse to achieve high-speed transmission in original frequency band.Although MIMO offers high-speed transmission, WCDMA with MIMO imports more inter-symbol interference (ISI) in the base of multi-path interference. The basic reasons of ISI are constrained strip width and time-delay spreading, equalization in the receiving end which is traditional method can handle it. This paper cite some common equalization method and discuss their complexity which is master key in the downlink, because if we can’t cut down the complexity, the phone behaved as receiving end must enlarge its size. However special with portable feature, the phone can’t accept the reality. To simplify the complexity of the receiving end, precoding technology developed by and by.Precoding includes linear and nonlinear. With simple realization, linear precoding is adopted generally. Although nonlinear precoding can approach the upper limit of channel capacity, it’s defeated because of the implement’s complexity.This paper summarized the criterion of precoding designing by research SVD precoding and the method of codebook which is adopted by communication protocol. And the paper attempted at importing the codebook into SVD precoding.Also the paper put forward a synthetic phase precoding. The idea of designing is that the receiving end detect orthotropic signal with dot product between real and imaginary part. So the precoding needs to remove the phase interference of the channel, and orthogonalize the signals from two antennas. Compare with common precoding, it aims at simplified detecting process instead of modify resultful channel thoroughly.