ROADMAP: a robust ACK-driven media access protocol for mobile ad hoc networks

A new and reliable MAC protocol is proposed to reduce the number of control handshake messages, such as RTS (Request-To-Send) and CTS (Clear-To-Send), incurred prior to data transmission in ad hoc wireless networks. Such a handshake is currently being used in the IEEE 802.11 DFWMAC (Distributed Foundation Wireless MAC) protocol. Our protocol is power efficient since fewer control messages are being used. By overhearing the ACK message sent by the upstream node, a node can gain advance knowledge that data would be arriving and hence need only to initiate a CTS later on. In addition to this, we introduce reliability into the protocol using an acknowledgment message to indicate that the data transmitted has been reliably received. Issues related to collision of control messages are also addressed in this paper. The communication performance of our protocol is evaluated via simulation and we also compare it with the IEEE 802.11 DFWMAC. Results show that our protocol outperforms DFWMAC with fewer control overheads incurred and smaller end-to-end delay.