Rate Adaptive Space-Time Modulation Techniques for Combating Cochannel Interference

Space-time coding is a highly effective approach for combating fading in wireless communications and improving the capacity of wireless networks. However, a recent paper has shown that cochannel interference can degrade performance significantly in cellular systems. Here we design and demonstrate the interference suppression capability of low rate space-time codes. Optimal 1 b/s/Hz 2-space-time trellis codes with various number of states over and GF(4) are obtained through search. We also propose rate adaptive space-time modulation which can increase the overall throughput. The effectiveness of this proposed method is demonstrated by using 2-space-time codes in an orthogonal frequency division multiplexing (OFDM) system with 2 transmit and 2 receive antennas