LDPC-coded cooperative communications based on joint signal superposition and iterative decoding

Abstract

Motivated by the recent work on cooperative communications and LowDensity Parity-Check (LDPC) codes, this work introduces a cooperation scheme that integrates both cooperative transmit diversity utilizing signal superposition modulation and LDPC codes. Many wireless devices are unable to support multiple antennas and require being light in weight, consume less power and have affordable cost. In a multi-user environment, cooperative communications enable these single antenna devices to collaborate and share their resources including antennas, signal processing cababilities, power and bandwidth. Thus it provides transmit diversity in a different approach. Similarly, LDPC codes use low complexity iterative decoding algorithms compared to other channel error control codes. Our new scheme provides performance gain offered by integrating user cooperation based on partial signal superposition modulation, LDPC channel coding and soft iterative detection. The new scheme provides about 4 dB gain over direct transmission at interuser channel having only an average SNR of 0 dB.