Abstract:

To improve energy efficiency in cooperative relay system, an approach to optimize the energy consumption of cooperative hybrid automatic repeat request (HARQ) protocols with adaptive modulation over Nakagami-m fading channel is proposed. Through modeling the state transition diagram, the total energy consumption and outage probability performance are derived. Further, an optimization framework to minimize the total energy consumption is formulated, and an exhaustive search algorithm is presented. It is shown that the performance of cooperative HARQ is better than the noncooperative HARQ. In addition, the proposed crosslayer scheme can reach to about 80% energy savings over the nonoptimized system.

Key words: cross-layer design, hybrid automatic repeat request, adaptive modulation, energy consumption