Contention based energy efficient wireless sensor network — A survey

Wireless sensor network (WSN) consists of many small sensor nodes which are distributed in structured or unstructured manner. These sensor nodes are battery operated and hard to replace and recharge the battery of these nodes. Medium Access Control (MAC) plays an important role in wireless sensor network as MAC controls the radio signal in channel of communication between two or more sensor nodes. For designing the MAC protocols for WSN, the low power consumption by the nodes must be the main aim. Different synchronous & asynchronous MAC protocols of WSN are described briefly such as S-MAC, T-MAC, B-MAC, WISE-MAC, etc. on different parameter such as mechanism & strategy used, how collision can be avoided, advantages & disadvantages.