基于空时分组编码的MC-CDMA下行链路合并方案

基于空时分组编码的发射分集技术利用空间和时间分集 ,能有效抗多径 ,增强信道可靠性。将空时分组编码应用到MC -CDMA下行链路中 ,构建了一种新的多载波CDMA系统 (ST -MC -CD MA) ,通过在每个子载波信道中获得空间分集增益来提高系统性能。具体实现时 ,依据传统MC -CDMA信号合并方案 ,提出了ST -MC -CDMA空时译码后相应的四种合并方案。仿真结果验证了这 4种合并方案的优、缺点 ;并进一步证明 :在频率选择性瑞利衰落信道中 ,该系统比采用相同合并方案的传统MC -CDMA有明显的性能改善。

Combining Schemes in the Downlink of Space-Time Block-Coded MC-CDMA

The transmit diversity based on space-time coding, which exploits the diversities both in space and time domain, can combat fading to enhance the reliability of the wireless channel. In this paper, space-time block code is applied to the downlink MC-CDMA and a novel system called ST-MC-CDMA is proposed. The resulting diversity on each subcarrier combined with the inherent frequency diversity in MC-CDMA can greatly improve the performance of the system. According to the existing combining schemes in MC-CDMA, four corresponding combining formulas of this system are presented. Finally, simulations verify both the advantages and disadvantages of these combining schemes. In addition, the comparison results show that ST-MC-CDMA outperforms vastly the traditional MC-CDMA systems no matter which combining scheme is used in the frequency-selective fading channels.