Space-time coding for time and frequency asynchronous CoMP transmissions

This paper deals with time and frequency offset in coordinated multipoint (CoMP) transmission/reception networks by using distributed linear convolutional space-time coding (DLC-STC). We first prove that perfect time synchronization is impractical for CoMP transmission/reception networks. Then the DLC-STC scheme, in which exact time synchronization at the relay nodes is unnecessary, is proposed for the CoMP joint processing mode (CoMP-JP). Finally, we show the detecting method by minimum mean-squared error decision-feedback equalizer (MMSE-DFE) receivers with any frequency offsets. Simulation results show that with MMSE-DFE receivers, the proposed DLC-STC scheme outperforms the delay diversity scheme and the MMSE-DFE receivers can achieve the same diversity orders as the maximum likelihood sequence detection (MLSD) receivers.