Throughput Maximization by Adaptive Threshold Adjustment for AMC Systems

The mechanisms of adaptive modulation and coding (AMC) and hybrid automatic repeat request (HARQ) are two important schemes in modern wireless communication systems. In practical system design, the AMC mechanism is usually implemented with fixed switching thresholds for the modulation and coding schemes (MCS), and suffers from performance degradation. To mitigate this problem, a novel algorithm is proposed in this paper to maximize the system throughput. The algorithm adaptively adjusts the AMC threshold values according to the HARQ acknowledge (ACK) feedback information in each transmission round so that the AMC mechanism can select the best MCS with nearly optimal thresholds. Simulations are conducted to show that the system throughput is indeed improved by the proposed adaptive threshold adjustment algorithm.