Cross-Layer Subchannel Assignment with Multicast over WiMAX Networks

This paper considers the problem of video stream multicasting over worldwide interoperability for microwave access (WiMAX) networks. Since the MAC layer of a WiMAX network is connection-oriented, each subscriber must be allocated bandwidth from base stations before establishing a connection. However, bad connection quality may decrease the network efficiency. While a base station allocates subchannels to subscribers, variations in channel fading often affect the transmission rate. This paper proposes several transmission scheduling schemes to avoid the effects of channel diversity and improve transmission performance. Our strategy is to divide subscribers into several groups depending on the signal-to-noise rate (SNR) of allocatable channel(s). The objective of this study is to find an optimal schedule to minimize the transmission latency of video streaming and maximize base station capacity. Simulations show that the proposed methods FF and RFF yield efficient multicast scheduling and outperform previous methods.