Supporting MAC Layer Multicast in IEEE 802.11n: Issues and Solutions

In this paper, we propose a MAC layer multicast protocol for 802.11n WLAN for the first time. In IEEE 802.11n, new feature at MAC layer, such as frame aggregation and more flexible link adaptation are defined to increase the effective throughput. Recently, several multicast protocols at MAC layer have been proposed for WLAN. However, these protocols don\´t consider the new features defined in 802.11n, and cannot satisfy the requirement of fast speed transmission. In our proposed multicast protocol, "double piggyback mode multicast protocol (DPMM)", we use new features (frame aggregation and link adaptation) in 802.1 In to improve the multicast throughput. With DPMM, ACK packets are eliminated and collisions of control frames are avoided. A CHs (cluster heads) selection mechanism using success threshold is also developed to further improve upon DPMM. Simulation results, using the OPNET, confirm that the improvements are encouraging.