MIMO ARQ With Multi-Bit Feedback: Outage Analysis
The authors study the asymptotic outage performance of INcremental Redundancy Automatic-Repeat-Request (INR-ARQ) transmission over Multiple-Input Multiple-Output (MIMO) block-fading channels with discrete input constellations. They first show that transmission with random codes using a discrete signal constellation across all transmit antennas achieves the optimal outage diversity given by the Singleton bound. They, then analyze the optimal SNR-exponent and outage diversity of INR-ARQ transmission over the MIMO block-fading channel. They show that a significant gain in outage diversity is obtained by providing more than one bit feedback at each ARQ round. Thus, the outage performance of INR-ARQ transmission can be remarkably improved with minimal additional overhead.