Layered space-time codes for wireless communications using multiple transmit antennas

Multiple-antenna systems provide very high capacity compared to single antenna systems in a Rayleigh fading environment. Space-time codes are channel codes designed to exploit this high capacity for multiple-antenna systems without requiring instantaneous channel knowledge at the transmitter. A practical concern for high data rate space-time codes is their decoding complexity. The decoding complexity with ML criterion can be prohibitively large. In this paper, we focus on layered space-time (LST) codes. Two types of LST codes, the horizontally-layered space-time (HLST) codes and the diagonally-layered space-time (DLST) codes, are presented. We analyze the performance of both types of LST codes under slow and fast fading conditions. We conclude that, in a slow fading environment, DLST codes have superior performance over HLST codes. The design criteria for DLST codes are proposed.