Novel association strategies for supporting multicast in WLANs with smart antennas

Multicast is an important service in Wireless Local Area Networks (WLANs) as it provides an efficient means to send packets to multiple stations at the same time. Unfortunately, the transmission of multicast packets in current WLANs is bounded by the subscribing stations with the lowest data rate. A key approach to improve multicast capacity is to deploy an association control strategy that maximizes one of the following objectives: multicast throughput or number of supported users. However, past work has not consider the use of smart antennas to minimize these objectives. In fact, they only consider grouping stations according to the data rate afforded by omni directional transmission from Access Points (APs). To this end, we consider a unique association control algorithm that considers the coverage and data rates afforded by smart antennas. Unfortunately, the problem is NP-hard by a reduction from the Maximum Coverage with Group Budget (MCG) problem. We, therefore, propose four heuristics and provide an in-depth study of the best performing heuristic via simulation. Our results show that the average load of APs can be reduced by up to 36.1%, and number of satisfied users can be increased by up to 237%. The average throughput of APs can be increased by up to 57.1%.