AN ADVANCED MAC PROTOCOL MIMO WLANS
[attachment=16629]

INTRODUCTION
WLANS can be largely benefited by utilizing distributed spatial multiplexing gain that can be achieved by cancelling multiuser interference using multiple antennas at transmitter/receiver side. However, the distributed coordination function (DCF) which is the fundamental channel access method of IEEE 802.11n is based on CSMA/CA[1] and thereby prevents the distributed spatial multiplexing by collision avoidance scheme[3]


NEW-CSMA/CA PROTOCOL
The standard CSMA/CA protocol does not allow multiple STA’s to transmit concurrently. In order to do so, we grouped the nodes of a network to multiple clusters. Each cluster is assigned with a fixed number of nodes. A cluster, which generates the data packets, is termed as source cluster. The number of concurrent streams that can be efficiently decoded limits maximum number of nodes in a cluster



PERFORMANCE ANALYSIS
In this paper we focus on Zero-forcing relaying network where all stations and relays are equipped with single antenna. We analyze the MAC layer performance by calculating and simulating the MAC throughput, head-of-line (HoL) delay and packet collision probability respectively .


CONCLUSION
In this paper we proposed an advanced CSMA/CA scheme which enables multiuser streams and reduces the collision probability in a network.This protocol showed a promising throughput and delay improvement compared to a reference system based on the IEEE 802.11. The proposed protocol can support applications with high data rate requirements as well as the ones with low delay constraints in a variety of networks.