A precoding technique based on time reversal for single-carrier IDMA systems

According to the high complexity of pre-coder in single-carrier interleave-division multiple access (IDMA) systems, in this paper, we propose a precoding technique based on time-reversal (TR) for single-carrier IDMA systems. The proposed scheme gets the channel impulse responses (CIR) through time-division duplexing (TDD) mode, and uses the time-reversed version of the CIR to pre-coder the transmitted signal at transmitter. The receiver adopts the iterative Linear Minimum Mean Square Error (LMMSE) frequency domain equalization (FDE) algorithm. Thus the pre-coder of transmitter is simple and easy to implement as compared with water filling pre-coder and optimal pre-coder, and the receiver can be simplified by canceling complex computation. The simulation results show that the performance of TR pre-coder is close to that of optimized pre-coder and that of water filling in single-carrier IDMA systems based on iterative LMMSE-FDE algorithm when signal to noise ratio (SNR) is higher than 3.5dB. The simulation results also demonstrate that TR pre-coder has potential advantages.