An improved data flushing MAC protocol for IEEE 802.11 wireless ad hoc network

In this paper, we propose a data flushing data transfer (DFDT) protocol. The distributed coordinate function (DCF) of IEEE 802.11 supports data transmissions using the data-ACK method and the request-to-send/clear-to-send (RTS/CTS) method. The data-ACK method has low protocol overhead, however, the transmissions are prone to collision. Although the RTS/CTS mechanism reduces the probability of collisions of data packets, the handshaking generates extensive overhead. Another issue with the IEEE 802.11 DCF is the contention for channel access; much bandwidth is wasted with the contention, especially when the mean data length is short. DFDT is capable of sending out multiple data packets from the upper layer, after acquiring channel access by a successful contention, within one frame which we call compiled MPDU (cMPDU). Right after the transmission of the data frame, the destination nodes will reply an positive/negative acknowledgement in a consecutive manner. By using this method, the protocol overhead is relatively lowered while retaining service quality and the waste of bandwidth for contention is also reduced. Simulation results show that DFDT can handle higher traffic load and has better throughput then the IEEE 802.11 MAC protocol.