California Partners for Advanced Transportation Technology

WTRP (Wireless Token Ring Protocol) is a medium access control (MAC) protocol for wireless networks. The MAC protocol through which mobile stations can share a common broadcast channel is essential in wireless networks. In a IEEE 802.11 network, the contention among stations is not homogeneous due to the existence of hidden terminals, partially connected network topology, and random access. Consequently, quality of service (QoS) is not provided. WTRP supports guaranteed QoS in terms of bounded latency and reserved bandwidth which are crucial real time constraints of the applications. WTRP is efficient in the sense that it reduces the number of retransmissions due to collisions. It is fair in the sense that each station use the channel for equal amount of time. The stations take turn to transmit and are forced to give up the right to transmit after transmitting for a specified amount of time. It is a distributed protocol that supports many topologies since not all stations need to be connected to each other or to a central station. WTRP is robust against single node failure. WTRP recovers gracefully from multiple simultaneous faults. WTRP has applications to inter-access point coordination in ITS DSRC, safety-critical vehicle-to-vehicle networking, home networking and provides extensions to sensor networks and Mobile IP.