增强型MBMS系统中应用空时频编码的传输分集策略.pdfVIP

2008年2月 北 京 邮 电 大 学 学 报 Feb．2008 第31卷 第1期 Journal of Beijing University of Posts and Telecommunications VO1．31 NO．1 文章编号：1007—5321(2008)01—0125—05 增强型MBMS系统中应用空时频编码的传输分集策略 盛 煜， 彭木根， 王文博 (北京邮电大学 电信工程学院，北京 100876) 摘要：结合空时编码和循环延迟分集技术，将空时频编码引入增强一多媒体广播／组播业务(E—MBMS)网络中，提出 了一种有效的传输分集策略．该策略对广播／组播网络下的不同小区进行分组，对本小区内正交频分复用(OFDM) 帧f可相同载波上的符号进行空时编码；不同分组的小区在相同OFDM帧内的各子载波符号则使用循环延迟方案引 入频率分集，从而实现E—MBMS网络下的空时频编码．仿真结果表明，该策略可以明显改善小区边界用户的接收性 能，有效提高移动广播／组播网络的覆盖能力及吞吐量． 关 键 词：增强一多媒体广播／组播业务；空时编码；循环延迟分集；正交频分复用 中图分类号：TN929．53 文献标识码：A A Transmit Diversity Strategy with Space·-Time·-Frequency Coding Technique in Enhanced MBMS Networks SHENG Yu， PENG Mu—gen， WANG Wen—bo (School of Telecommunication Engineering，Beijing University of Posts and Telecommunications，Beijing 100876，China) Abstract：A transmit diversity strategy in enhanced multimedia broadcast／multicast service(E— MBMS)networks was proposed，in which the space—time—frequency coding technique was adopted，i． e．，the frequency diversity and the cyclic delay diversity were jointly designed to enhance the tradition— al space-time coding scheme．The broadcast／multicast cells in the proposal were divided into multiple cell groups．And the orthogonal frequency division multiplexing(OFDM)symbols in the same cell be— tween different frames were executed with space—time coding schemes，meanwhile，the proper cyclic delay was obtained to the frequency diversity gain in the different cell groups．Simulation results show that the proposal can improve the bit error rate performances efficiently and get increasing of coverage and throughput，especially for those users who are at the cell edges． Key words：enhanced multimedia broadcast／mult