Adaptive medium access control scheme for wireless LAN
First Claim
1. In a digital data radio communication 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 messages and data are transmitted, each of said plurality of frames being divided into three intervals, the first interval for transmission from said base station to said plurality of remote stations, the second interval for contention free transmission from said plurality of remote stations to said base station, and the third interval for contention access by said plurality of said remote stations for transmission to said base station; and
means for including control indicia in a transmission from said base station to a given remote station that is indicative of the probability of said given remote station gaining access during said third interval.
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0 Petitions
Accused Products
Abstract
A Medium Access (MAC) Protocol is utilized for wireless radio access for a plurality of remote stations to a base station on a LAN. There is a time division fixed frame structure in which time is slotted, and time slots are grouped into fixed frames consisting of data and control subframes or periods. The fixed frame structure consists of three periods (A, B, and C) along with their respective headers. The first period, the A period, is used exclusively for data transfer from the base station to the remote stations. The following period, the B period, is used for contention-free data transfer from the remote stations to the base station. The allocation of the data slots in the A and B periods is performed by the base station. The last period of the frame, designated as the C period, is used for the transmission of reservation requests and data from the remote stations to the base station in a random-access contention mode using a slotted Aloha protocol. The duration of the three periods may be varied using a movable boundary technique.
367 Citations
50 Claims
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1. In a digital data radio communication system, the combination comprising:
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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 messages and data are transmitted, each of said plurality of frames being divided into three intervals, the first interval for transmission from said base station to said plurality of remote stations, the second interval for contention free transmission from said plurality of remote stations to said base station, and the third interval for contention access by said plurality of said remote stations for transmission to said base station; and means for including control indicia in a transmission from said base station to a given remote station that is indicative of the probability of said given remote station gaining access during said third interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. In a digital data radio communications system the combination comprising:
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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. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method of operating a digital data radio communication 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:
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defining a plurality of frames, at said base station, during which messages and data are transmitted, each of said plurality of frames being divided into three intervals, the first interval for transmission from said base station to said plurality of remote stations, the second interval for contention free transmission from said plurality of remote stations to said base station, and the third interval for contention access by said plurality of remote stations for transmission to said base station; and including control indicia in a transmission from said base station to a given remote station that is indicative of the probability of said given remote station gaining access during said third interval. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. 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:
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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. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47, 48)
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49. In a digital data radio communications system the combination comprising:
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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.
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50. In a digital data radio communications system the combination comprising:
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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.
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Specification