关键词: 长期演进系统, 循环延迟, 多输入多输出系统, 空间－多径分集, 单载波频域均衡

Abstract: 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 com-plexity． 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 de-modulation complexity; and that，when outage probability reaches 10^-3，the proposed scheme leads to 2 ～4dB of gain under Rayleigh channel and at least 1. 5dB of gain under extended pedestrian channel．

Key words: long-term evolution system, cyclic delay, multiple input multiple output system, spatial-multipath diversity, single-carrier frequency domain equalization