Neighbour -Aware, Collision Avoidance MAC Protocol (NCMac) for Mobile Ad Hoc Networks

IEEE 802.11 [1] has become the standard for wireless LAN's both in infrastructure and in ad hoc mode. The standard specifies the medium access control mechanism, distributed coordination function (DCF). Deploying the 802.11 DCF in wireless multi-hop networks leads to inefficient utilization of bandwidth and energy due to many unnecessary collisions. To attenuate these problems we propose a neighbour -aware collision avoidance MAC protocol (NCMac). The NCMac protocol defines algorithms to estimate minimum and maximum contention window (CW) sizes (CW
_min
, CW
_max
) taking into account the number of neighbours in the one-hop neighbourhood and the energy level of the battery. A novel resetting algorithm applied both after a successful and unsuccessful transmission has been also designed. In [3] we have already proposed a similar algorithm to calculate the CW
_min
(but not CW
_max
). However, the resetting algorithm of the NCMac is enhanced and unified and the NCMac does not modify the backoff algorithm defined in [1]. The NCMac protocol achieves a better throughput and noticeably reduces the number of collisions resulting in a longer network lifetime and a later dead of the first node as compared with the IEEE 802.11 DCF standard.