Supporting Real-Time Multimedia Traffic in a Wireless LAN

The Group Allocation Multiple Access (GAMA) protocol for scheduling real-time and datagram traffic in a singlechannel, single-hop, packet-radio network is specified and analyzed. By maintaining a dynamically-sized cycle that changes in length depending on the amount of network traffic, GAMA is able to provide bandwidth guarantees to the members of its “transmission group”; member stations are able to transmit real-time data at a specified rate. Each cycle contains a contention period and a group-transmission period; a station with data to send competes for the right to be added to the transmission group by successfully completing an RTS/CTS message exchange during the contention period. Once a station is a member of the transmission group, it is able to transmit a collision-free data packet during each cycle. As long as a station has data to send, it maintains its position in the group. This can be viewed as either allowing stations to “share the floor” in an organized manner, or as establishing frames that are not synchronized on a slot-basis and vary their length dynamically based on demand. The throughput and average delay of GAMA are presented and analyzed.