一种采用松弛正交预编码的多址接入方法

Multiple access method using a relaxed orthogonal precoder

在多址方法设计中,有效管理多个并发通信间的共道干扰是提升系统频谱效率的关键。现有干扰管理的思路是使多路信号在传输过程中相互正交,然而在多用户多输入多输出系统中,发射机和接收机的数量以及它们的天线配置严格制约了系统能够支持的正交并发通信的数量。针对这一问题,提出一种应用于多用户多输入多输出下行通信的基于松弛正交预编码的多址接入方法,通过引入一个正交幅度调节函数,在一个符号周期内对预编码的幅度进行调整,利用调节后的预编码进行信号处理和发送,可以将对多用户信号在空域上严格正交的要求放宽到相关意义上的正交;相应地,接收机采用相关运算对期望信号进行检测,可以利用幅度调节函数之间的正交性在判决时刻消除共道干扰的影响。仿真结果表明,所提方法可以在不增加频谱资源消耗的情况下,显著提高系统容纳的用户数量,改善系统的频谱效率。

In medium access control(MAC)method design,the effective management of co-channel interference(CCI)among multiple concurrent transmissions is critical to enhancing a system’s spectrum efficiency(SE).The main idea of existing interference management(IM)methods is to make multiple signals orthogonal to each other during their transmissions.However,in the multi-user multiple input multiple output(MU-MIMO)system,the numbers of transmitters and receivers and their antenna settings highly restrict the number of orthogonal concurrent data transmissions that the system can support.To remedy such deficiency,this paper proposes a relaxed orthogonal precoder based multiple access(ROPMA)method for MU-MIMO downlink transmission.By introducing an orthogonal amplitude tuning function to adjust the precoder’s amplitude in a symbol duration,and then using the adjusted precoder for signal processing and transmission,the requirement of strict orthogonality of multi-user signals in the spatial domain can be relaxed to the orthogonality in the sense of correlation.Accordingly,the receiver employs correlation based desired signal detection;by exploiting the orthogonality of amplitude tuning functions,the influence of the CCI can be eliminated at the decision time.Our simulation results have shown that the proposed method can significantly increase the number of users that the system can accommodate and improve the system’s SE without consuming the extra spectrum resource.