WiMARK: An intelligent MAC protocol for Ad Hoc WLANs with Busy Tone and Power Control

Ad hoc networks have been known to be extremely vulnerable to the hidden and exposed terminal problems, which consequently reduce dramatically the network capacity. The total lack of knowledge of the surrounding environment, a characteristic in-wrought with ad-hoc networking, is in most cases the main reason for the degradation of performance in Wireless Mobile Ad hoc Networks (MANETs). To effectively address this problem Wireless Medium Access through Record Keeping(WiMARK), a hybrid approach, is being proposed, combining the busy tone, the table-driven and the power-control protocols. Each node in WiMARK uses a local matrix where it stores the current condition of all its neighbouring nodes. The records of the matrix get updated by periodically transmitted Status Messages (SMs), which also have an RTS-like role in initiating a data packet transmission. The SMs that denote a critical change of status (i.e. the transition of a node from IDLE to RECEIVING_DATA state) are protected by a busy tone in order to be given the highest priority and thus maximize the chances of a successful transmission. In conjunction with this, the use of the power control scheme ensures the best possible bandwidth allocation in the area of interest. Index Terms – MANET, ad hoc, medium access protocol(MAC), busy tone, power control.