The use of directional antennas provides the spatial reuse of the channel and achieves higher network capacity. New MAC protocol is required for the directional antenna, which is studied in this thesis. This thesis describes the implementation of multibeam directional antenna, and the node based backoff and deafness avoidance schemes in the discrete event network simulator (known as the Riverbed Modeler), for supporting the multibeam communication between nodes using the IEEE 802.11 based CSMA/CA MAC protocol. The issues that arise due to the use of the multibeam directional antenna are considered and the solutions to overcome them provided. A major issue in multibeam communication is the synchronization among all the beams of a node for concurrent packet transmission and reception; this problem is resolved by using the constant backoff after the distributed inter frame spacing (DIFS) for each beam in a node. Another important issue is deafness, which is resolved by improving existing CSMA/CA mechanism by implementing a scheduling control packet. The multibeam directional MAC is able to successfully send packets from multiple beams of a node concurrently as compared to the omnidirectional MAC, which can send only one packet from a single node.