Group Allocation Multiple Access in Single-Channel Wireless LANs

The Group Allocation Multiple Access (GAMA) protocol for scheduling variable-length packet transmissions in a 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 the advantages of both TDMA and CSMA. 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; to validate our analysis, the results of both models are compared to the throughput and delay produced by a simulation of GAMA.