LA and HARQ combined optimization based on QoS prediction

Link Adaptation (LA) and Hybrid Automatic Repeat reQuest (HARQ) are seen as effective methods to enhance performance of wireless communications. However, most of them tend to divide LA and HARQ into two independent parts, and optimization has been made in each part respectively. It is obvious that LA promotes efficiency by decreasing robustness of wireless transmissions, while HARQ is just the opposite. So LA and HARQ should be optimized with one unified criterion to make full use of capability of wireless communications. To this question, a unified QoS criterion for LA and HARQ is proposed. Then combined optimization on LA and HARQ is deduced based on this proposed criterion. By placing both the two techniques under one evaluating framework of QoS, LA and HARQ are not optimized independently but synthetically from the view of QoS, and performance gain is achieved. Both theoretical demonstration and simulation results have validated that the proposed optimization will enhance QoS for wireless transmissions.