Enhanced adaptive modulation and coding schemes based on multiple channel reportings for wireless multicast systems

This paper shows various schemes to change Modulation and Coding Schemes(MCS) adaptively for multicasting. Applying Adaptive Modulation and Coding(AMC) scheme to multicasting mill show better performance in view of spectrum efficiency aspect than fixing MCS level. Since there exist multiple receivers for a data in multicasting, there is much more difficulty in determining the overall MCS level which satisfies all the receivers. Based on the channel quality information of the receivers, the source can determine the overall MCS level by three schemes; minimum MCS algorithm, average MCS algorithm, and weighted average MCS algorithm. Here, a tradeoff between spectrum efficiency and robustness exists: minimum MCS algorithm chooses robustness that guarantees low error rate to all the receivers, while average MCS algorithm chooses spectrum efficiency to improve throughput performance. A compromise between spectrum efficiency and robustness can be made by introducing weights to averaging MCS. Depending on the parameters related to the weights, more robustness or spectrum efficiency can be achieved. This paper presents numerical analysis showing the performance of the proposed schemes and a conventional scheme. Also simulation is presented to verify the numerical analysis results and shows the performance of weighted MCS algorithm.