Performance comparison of adaptive modulation scheme for OFDM system using cluster

Adaptive modulation and coding (AMC), which has a number of variation levels in accordance with the fading channel variation, is a promising technique for communication systems. In this paper, we present the AMC method using the cluster in OFDM system for bandwidth efficiency and performance improvement. The AMC schemes applied into each cluster or some clusters are determined by the minimum or the average SNR value among all the subcarriers within the corresponding cluster. It is important to find the optimal information for cluster because AMC performance can be varied according to the number and position of cluster. It is shown by computer simulation that the AMC method outperforms the fixed modulation in terms of outage probability and bandwidth efficiency and its performance can be determined by the position and number of clusters.