MEDIA ACCESS CONTROL PROTOCOL WITH PRIORITY AND CONTENTION-FREE INTERVALS

An access contention scheme having both multi-level priorities and a contention-free access indicator 130 for use by a station 12 in a network of stations 10. A station 12 having a frame to transmit determines from a detected contention control indicator 130 if it is permitted to contend for access to a transmission medium14 during a contention period 290. The station 12 determines if the contention control indicator 130 indicates a contention-free access and, if the contention control indicator 130 indicates a contention- free access, the station 12 determines if a channel access priority level associated with the frame to be transmitted is higher than a channel access priority level 144 associated with a last transmitted frame. If so, the station 12 detects whether any station in the network of stations intends to contend for access to the medium 14 at a channel access priority level that is higher than the channel access priority level associated with the frame to be transmitted. If so, the station 12 defers contention for access.