Differential space-code modulation for interference suppression
A differential space-time modulation (DSTM) scheme, which fully exploits the receive/transmit antenna diversity, was recently proposed to perform demodulation without channel state information. DSTM is attractive in fast flat fading channels where accurate channel estimation is difficult to obtain. However, we show that this technique is interference-sensitive and is likely to deteriorate or even break down in the presence of interferences. In this paper, we propose a new coding and modulation scheme, referred to as differential space-code modulation (DSCM), which is interference resistant. We show that DSCM can be used to provide similar bit-error-rate (BER) performance to that of DSTM in the absence of interference, but significantly outperforms the latter when interferences, especially strong ones, are present. Moreover, DSCM requires lower transmission power and hence is more suitable for covert communications.