Multicast medium access control in wireless ad hoc network

The basic carrier sense multiaccess control scheme for multicast communications in wireless ad hoc network suffers from the well know hidden terminal problem. The data packet collision probability is relatively high, and the packet delivery ratio is sensitive to the network topology, nodes distribution and traffic load. This paper generalizes the virtual earner sense collision avoidance approach to reduce packet collisions. The sender and receivers exchange RTS and CTS packets to reserve the channel. When more than one receivers reply with CTS packets, the sender will detect an "expected" collision which may be interpreted as a valid "clear-to-send" signal provided the collision satisfies the given timing requirements. Together with a receiver-initiated local recovery mechanism, the reliability of multicast communications can be improved to almost 100%.