Performance evaluation of MIMO-aware media access control protocol

Multiple-Input and Multiple-Output (MIMO) systems are recently being recognized for achieving simultaneous transmissions on wireless channels that overlap in time. As a result, new scheduling mechanisms are required that coordinate these multiple transmissions among wireless stations which share a single wireless channel. This paper proposes a new distributed MIMO-aware medium access control (MA-MAC) protocol which allows two simultaneous transmissions overlapped in time when stations are equipped with MIMO. The proposed MA-MAC protocol is compatible with the existing IEEE 802.11 standard for wireless local area networks (WLANs). It uses weighted nulling and intelligent packet fragmentation for its operation. Detailed performance analysis of MA-MAC protocol is carried out using the NS-2 network simulator. Firstly, this paper presents the concept of weighted nulling that is necessary for simultaneous transmissions on wireless channel, followed by a detailed description of the proposed MA-MAC scheme. Secondly, it presents the performance of MA-MAC scheme under various network scenarios that includes both saturated and unsaturated conditions. This paper presents the performance improvements shown by MA-MAC when compared with an existing medium access control scheme which is also proposed for scheduling simultaneous transmissions for MIMO.