Design and Implementation of an Efficient and Adaptive Asynchronous MPR MAC Protocol for WLAN

Multi-Packet Reception (MPR) technology helps in increasing throughput of Wireless Local Area Networks (WLANs) significantly by allowing multiple nodes to transmit even in the presence of ongoing transmissions in the wireless medium. Instead of discouraging overlapping transmissions as in 802.11 Distributed Coordinated Function (DCF) Medium Access Control (MAC), the proposed MAC layer must facilitate their occurrence in order to benefit from MPR. At the same time, the MAC should retain the distributed manner in which nodes access the medium, as this is a key reason behind the success of DCF MAC. The proposed algorithm for an efficient and adaptive asynchronous MPR MAC protocol uses the Backoff Timer mechanism of DCF MAC. The MAC rules for a node in terms of freezing or decrementing its Backoff Timer are modified to increase the system throughput, reduce collisions and reduce the ACK delays. The MAC protocols are simulated and their performance parameters like saturation throughput, packet delay, packet dropping probability and packet collision probability are analyzed.