Adaptive medium access control scheme for wireless LAN

In a digital data radio communications system the combination comprising:

• a plurality of remote stations, each of which includes a transceiver;
• a base station having a transceiver for radio communications with the transceivers of each of said plurality of remote stations, said base station including:
• means for defining a plurality of frames of fixed frame length, each of said frames being divided into three periods A, B and C with each period being divided into slots, including headers, with the slot sizes in the A and B periods being equal in size and being referred to as regular sized slots, and each accommodating one wireless data packet, with the slots in the C period being mini-slots which are smaller by a predetermined factor than the slots in the A and B periods, with each such mini-slot accommodating one wireless control packet, with the A period being for communications from said base station to said plurality of remote stations, the B period being for allocated communications from said plurality of remote stations to said base station, and the C period being for access by contention for communications from said remote stations to said base station;
• means for varying each of the A, B and C periods as a function of message traffic load on the system;
• and
• means for including control indicia in at least one of the A, B and C periods that is indicative of the probability of a remote station gaining access for communication to said base station in the C period, including means for changing said control indicia from one frame to the next as a function of an estimate of the number of remote stations contending for access.

A method of operating a digital data radio communications system which includes a plurality of remote stations, each of which includes a transceiver, and a base station having a transceiver for radio communications with the transceivers of each of said plurality of remote stations, said method comprising the steps of:

• defining a plurality of frames, at said base station, of fixed frame length, each of said frames being divided into three periods A, B and C with each period being divided into slots, including headers, with the slot sizes in the A and B periods being equal in size and being referred to as regular sized slots, and each accommodating one wireless data packet, with the slots in the C period being mini-slots which are smaller by a predetermined factor than the slots in the A and B periods, with each such mini-slot accommodating one wireless control packet, with the A period being for communications from said base station to said plurality of remote stations, the B period being for allocated communications from said plurality of remote stations to said base station, and the C period being for access by contention for communications from said remote stations to said base station;
• varying the duration of each of the A, B and C periods as a function of message traffic load on the system;
• and
• including control indicia in one of the A, B and C periods that is indicative of the probability of a remote station gaining access for communication to said base station in the C period, including means for changing said control indicia from one frame to the next as a function of the number of remote stations contending for access.

In a digital data radio communications system the combination comprising:

• a plurality of remote stations, each of which includes a transceiver;
• a base station having a transceiver for radio communications with the transceivers of each of said plurality of remote stations, said base station including means for defining a plurality of frames during which information is transmitted between said plurality of remote stations and said base station, with a portion of each frame being allocated for contention access by said plurality of remote stations for transmission to said base station;
• means for providing an estimation of the number of remote stations that attempt to transmit based on feedback information in transmissions from remote stations in at least a previous frame;
• and
• means for a remote station to determine whether to transmit in a given frame as a function of said estimation.

In a digital data radio communications system the combination comprising:

• a plurality of remote stations, each of which includes a transceiver;
• a base station having a transceiver for radio communications with the transceivers of each of said plurality of remote stations, said base station including means for defining a plurality of frames during which information is transmitted between said plurality of remote stations and said base station, with a portion of each frame being allocated for contention access by said plurality of remote stations for transmission to said base station;
• means for providing an indication in a transmission of information from a remote station to said base station of whether or not there has been a previous attempt to transmit this information;
• means for providing an estimation of the number of remote stations that attempt to transmit based on said indication in transmissions from remote stations in at least a previous frame;
• and
• means for a remote station to determine whether to transmit in a given frame as a function of said estimation.