LTE上行系统循环延迟分集接收方案的设计

Design of Cyclic Delay Diversity Receiving Scheme in LTE Uplink System

在长期演进（LTE）系统上行链路中,基站因受限于发射天线数而无法获得较好的分集增益及系统性能.为此,文中提出了一种利用循环延迟叠加方法获得空间-多径满分集的接收方案.首先直接叠加不同接收天线上经过循环延迟的信号,然后做频域的最小均方误差线性均衡,最后进行逐个符号的检测.当不同接收天线选择合适的循环延迟时,文中方案能够以较低的解调复杂度获得系统的空间-多径满分集增益.仿真结果表明：相对于LTE系统上行链路中现有的接收端天线选择方案,文中方案不仅能够获得与天线选择相同的接收分集增益,而且能够获得比天线选择方案更高的编码增益,同时不增加系统的解调复杂度;在中断概率为10-3时,文中方案在瑞利信道下的系统性能提升2~4d B,在LTE扩展步行信道下的系统性能提升1.5 d B以上.

For the lack of transmitting antenna in long-term evolution（ LTE） uplink system,base stations cannot obtain a good diversity gain and system performance. In order to solve this problem,a novel scheme using cyclic delay combining technique at the receiver is proposed to achieve full spatial-multipath diversity. In this scheme,cyclic delayed copy signals at different receiving antennas are combined. Then,the minimum mean square error equalization in frequency domain is made and the signal is detected symbol by symbol. When an appropriate cyclic delay shift is chosen,the system can obtain a maximum spatial-multipath diversity gain with low demodulation complexity. Simulated results indicate that,in comparison with the existing antenna selection schemes in LTE uplink system,the proposed scheme helps acquire the same diversity gain and a higher coding gain without additional demodulation complexity; and that,when outage probability reaches 10-3,the proposed scheme leads to 2 ~ 4 d B of gain under Rayleigh channel and at least 1. 5 d B of gain under extended pedestrian channel.