Node-blockage reduction and removal of hidden-terminal problem of CSMA/CA MAC protocol

CSMA/CA is an important MAC protocol for wireless LAN that uses short RTS/CTS control messages for the avoidance of collision. Although it has certain advantages for accessing of contended medium, it blocks some other nodes unnecessarily, especially the nodes that reside in the opposite sides of the communication between the source and the destination pair, thereby reducing network throughput. Also there exists a hidden-terminal (HT) problem in CSMA/CA that further reduces the network performance. In this paper, we propose two methods for enhancement of CSMA/CA. In the first method, some modifications of CSMA/CA have been made for the reduction of node-blockage based on the communication of received power-level of the receiver and the NAV-values of RTS/CTS messages. On the other hand the second method deals with the removal of HT problem using the RTS control messages of the nodes that create the HT problem. An analytical model for each enhancement is proposed which shows better performance over the original CSMA/CA protocol.