Extended low-density parity-check codes for feedback-based cooperative diversity schemes

Cooperative diversity or user cooperation achieves the diversity gain without adding physical antennas to the users or mobile stations. The users work in a cooperative fashion by using their single antennas to create a virtual transmit diversity, called relay diversity or cooperative diversity. The diversity gain achieved by cooperative diversity can be further improved using error correction codes. Low-density parity-check (LDPC) codes are linear block codes with good error correction capabilities. The authors present a novel approach using extended LDPC codes to increase the diversity gain in cooperative diversity. The authors also compare the extended LDPC codes with the punctured LDPC codes in a cooperative diversity and show that there is a performance-complexity tradeoff between the punctured and the extended LDPC codes in the cooperative diversity. Furthermore, the authors will propose two feedback-based protocols for cooperative diversity and compare their throughput with non-feedback-based cooperative diversity using extended LDPC codes.