Enhancement of packetised-preamble based MAC protocols: A solution to Hidden-Node problem in WSNs

In WSNs, collision avoidance and energy saving methods on MAC layer have become challenging research goals. Collision may happen because of Hidden-Node problem. It occurs when a sender is out of range of another sender and they try simultaneously sending data to a common receiver. IEEE802.11 RTS/CTS mechanism partly overcome this problem but a major drawback is that we cannot avoid RTS/CTS control packet collisions. This paper proposes a method to avoid collision among hidden transmitters that decide to send data to a sink via `One´ relay node concurrently. Our solution is to add a predefined handshaking signal called COL (Collision) which is applicable for any packetised-preamble MAC protocol. If receiver recognises a collision it sends COL message to the channel and afterwards all senders postpone data transfer process and save energy. Performance analysis of proposed method proves its viability and effectiveness for the problem.