An enhancement of the IEEE 802.11 MAC for multihop ad hoc networks

The IEEE 802.11 protocol solves hidden terminal problem using a four way handshaking mechanism. In this protocol, channel probing and reservation are made by using a small request-to-send (RTS) frame at the beginning of a transmission. This effectively detects and avoids collisions. However, the protocol lacks the ability to release or reallocate a channel that was reserved but not used. For multihops, like Mobile Ad hoc NETworks (MANET), this often keeps the channel unnecessarily inaccessible resulting in inefficient channel utilization. In this paper, we therefore propose a new mechanism to improve performance of IEEE 802.11 in MANET. Our mechanism utilizes channel capacity that is otherwise wasted. This leads to a higher yield in throughput by up to 10%. In addition, our proposed mechanism is free from compatibility problems with standard IEEE 802.11. Results from extensive simulations verify the effectiveness of our scheme.