Abstract
In performing video multicast over WiMAX networks, AMC enables the BSs to be able to select an appropriate modulation method in accordance with the transmission objective, namely to improve the video quality or to maximize the bandwidth utilization efficiency. However, by choosing the modulation method which maximizes the video quality at all of the SSs, the bandwidth utilization efficiency is reduced and vice versa. In addition, because wireless channels are noisy, FEC is always employed for video multicast. However, by choosing high FEC ratio, the video quality is improved but the bandwidth utilization efficiency is degraded and vice versa. In other words, a tradeoff exists between the video quality and the bandwidth utilization efficiency for video multicast over WiMAX networks. Accordingly, the present study proposes a scheme designated as Performance-Driven Robust Video Multicast (PDRVM), in which both the modulation method and the FEC ratio are determined adaptively in accordance with the network status by mathematical analyses. Simulation results show that PDRVM not only ensures that most of the SSs acquire a good video quality, but also makes the best possible use of the available transmission resources.