差分空间调制中的非恒模调制方法

差分空间调制(DSM)由于不依靠信道状态信息(CSI)而备受关注。传统的DSM采用了恒模调制的方法，例如相移键控(PSK)，但是在高速传输时PSK对星座图的空间自由度利用很低。针对该问题提出了一种DSM系统中的非恒模调制方法，通过对发射信号做相关预编码处理，使之消除非恒模调制在DSM系统中存在的幅度迭代问题。除此之外，为了使之可以体现分集增益，通过减小传输速率来达到满分集增益，并且加入一个功率均衡项来使该系统可以利用非恒模调制。仿真结果表明所提算法随着信噪比的提高，性能会逐渐优于PSK。

Differential spatial modulation using non-constant modulus constellations

Differential spatial modulation (DSM) is concerned because it does not rely on any channel state information (CSI). The traditional DSM uses equal energy constellations,such as phase shift keying (PSK). However,in high-speed transmission,PSK has a lower noise immunity than non-constant modulus constellations,and with the improvement of the modulation order,the disadvantage is particularly evident. For this problem,a non-constant modulus modulation method in DSM system is proposed. The amplitude iteration problem of non-constant modulus modulation in DSM system is eliminated by a precoding processing at the transmitter. In addition,in order to obtain the diversity gain,a method that reduces the transmission rate to achieve full diversity gain is adopted and a power balance is added to make the system be able to use non-constant mode modulation. The simulation results show that the performance of the proposed algorithm is better than that of PSK with the improvement of signal-to-noise ratio(SNR).