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US5644576A
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Medium access control scheme for wireless LAN using a variable length interleaved time division frame
Assignee: International Business Machines Corp
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Filing: 1995-05-16
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Granted: 1997-07-01
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Expires: 2015-05-16
Abstract
Abstract A Medium Access (MAC) Protocol is utilized for wireless access, preferrably over a radio frequency channel, for a plurality of remote stations to a base station on a LAN. The MAC protocol is based on a reservation scheme for user data traffic and a random access technique for control and signalling traffic. There is a time division frame structure in which time is slotted. Time slots are grouped into variable length periods. The variable frame structure consists of a frame header followed by interleaved periods of different types (type A, B or C). Type A periods are allocated to the outbound channel which is used for data transfer from the base station to the remote stations. Type B periods, are allocated to the inbound channel that is used for contention-free data transfer from the remote stations to the base station. Allocation of the data slots in the A and B periods is performed by the base station. Type C periods are reserved to the control channel used for 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 and sequence of periods may be varied by using a technique for interleaving periods of different types. The base station estimates the number of actively transmitting remote stations utilizing feedback information from the remote stations. This estimate is broadcast to the remote stations as control indicia to control their transmission attempts in C slots, thus yielding high transmission efficiency.
Inventors
- 👤 Frederic Jacques Bauchot
- 👤 Frederic Bernard Lefevre
- 👤 Luc Louis Revardel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:23
CPC Classifications
H; H04; H04W; H04W74/00; H04W74/02; H04L; H04L12/00; H04L12/64; H04W72/00; H04W72/50; H04W72/52; H04W74/04; H04W74/08; H04W84/00; H04W84/02; H04W84/10; H04W84/12
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
196 words
A digital communication system comprising: a plurality of remote stations, each including a transceiver for communication over a shared medium; a base station having a transceiver for communication over said shared medium with the transceivers of each of said plurality of remote stations, said base station including: a means for defining a sequence of time frames during which messages and data are transmitted over said shared medium, each said time frame being divided into at least three types of time slots, a first type A time slot for outbound transmission from said base station to said plurality of remote stations, a second type B time slot for contention free inbound transmission from said plurality of remote stations to said base station and a third type C time slot for contention access by said plurality of remote stations for transmission over said shared medium said defining means further including a means responsive to traffic load on said shared medium for allocating in a given time frame a variable number of said type A, type B and type C slots; and a means for interleaving within said given time frame groups of consecutive slots of the same type.
Claim 2
Dependent Claim
196 words
A digital communication system comprising: a plurality of remote stations, each including a transceiver for communication over a shared medium; a base station having a transceiver for communication over said shared medium with the transceivers of each of said plurality of remote stations, said base station including: a means for defining a sequence of time frames during which messages and data are transmitted over said shared medium, each said time frame being divided into at least three types of time slots, a first type A time slot for outbound transmission from said base station to said plurality of remote stations, a second type B time slot for contention free inbound transmission from said plurality of remote stations to said base station and a third type C time slot for contention access by said plurality of remote stations for transmission over said shared medium said defining means further including a means responsive to traffic load on said shared medium for allocating in a given time frame a variable number of said type A, type B and type C slots; and a means for interleaving within said given time frame groups of consecutive slots of the same type.
Claim 3
Dependent Claim
26 words
The system of claim 1 wherein each transceiver includes a frequency hopping radio signaling means and wherein said shared medium is a wireless radio frequency channel.
Claim 4
Dependent Claim
31 words
The system of claim 2 wherein said means for defining a sequence of time frames includes a means for spreading said given time frame over one or more frequency hopping periods.
Claim 5
Dependent Claim
25 words
The system of claim 3 wherein said interleaving means includes a means for inserting in said given time frame a frequency hopping type time slot.
Claim 6
Dependent Claim
26 words
The system of claim 4 wherein said interleaving means inserts at least one type C slot after each group of type A and type B slots.
Claim 7
Dependent Claim
30 words
The system of claim 5 wherein said means for interleaving within said time frame includes inserting at least one type C slot at the end of said given time frame.
Claim 8
Dependent Claim
96 words
The system of claim 6 wherein said means for allocating said time slots further comprises an outbound queue for queuing outbound transmission requests and an inbound queue for queuing inbound transmission requests; dequeue means which, in response to said interleaving means, dequeues one or more pending requests from either said outbound queue or said inbound queue; and means responsive to said dequeuing means for assigning a given period in said time frame to said one or more pending requests, said given period being type A for outbound transmission requests and type B for inbound transmissions requests.
Claim 9
Dependent Claim
30 words
The system of claim 7 wherein said interleaving means causes said dequeuing means to alternatively dequeue one or more pending requests from respectively said outbound queue and said inbound queue.
Claim 10
Dependent Claim
50 words
The system of claim 8 wherein said interleaving means causes said dequeueing means to dequeue in sequence one or more pending requests from said outbound queue, respectively inbound queue, if said inbound queue, respectively said outbound queue is empty, until the duration of said given periods exceeds a predetermined value.
Claim 11
Dependent Claim
25 words
The system of claim 9 wherein said interleaving means causes said assigning means to insert a type C period between two consecutive said given periods.
Claim 12
Dependent Claim
30 words
The system of claim 10 wherein said interleaving means limits the total number of successive type A, B and C periods in each said time frame to a predetermined value.
Claim 13
Dependent Claim
43 words
The system of claim 11 wherein said base station includes a 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 type C slots.
Claim 14
Dependent Claim
33 words
The system of claim 12 including means for providing an indication in a transmission from each said remote station to said base station of whether a given transmission of data is a retransmission.
Claim 15
Dependent Claim
32 words
The system of claim 13 including means for computing said control indicia as a function of said indications in transmissions from each said remote station over one or more said time frames.
Claim 16
Dependent Claim
27 words
The system of claim 14 wherein said means for computing said control indicia include means for recomputing said control indicia from one time frame to the next.
Claim 17
Dependent Claim
35 words
The system of claim 14 wherein said means for computing said control indicia include means for computing said indicia as a function of an estimate of the number of said remote stations contending for access.
Claim 18
Dependent Claim
52 words
The system of claim 16 wherein said means for computing said control indicia include means for computing said control indicia as a function of the ratio of the number of C slots in which a successful transmission from one of said remote stations occurs, relative to the total number of C slots.
Claim 19
Dependent Claim
67 words
The system of claim 16 wherein said means for computing said control indicia include means for computing said control indicia as a function of the ratio of the number of C slots in which said remote stations succeeded on a first attempt to transmit to said base station relative to the total number of remote stations that succeeded in an attempt to transmit to said base station.
Claim 20
Dependent Claim
28 words
The system of claim 18 wherein said type C slots are dedicated to contention access by said plurality of remote stations for inbound transmission to said base station.
Claim 21
Independent Claim
183 words
A medium access control method in a digital communication system of the type comprising a plurality of remote stations, each including a transceiver for communication over a shared medium and a base station having a transceiver for communication over said shared medium with the transceivers of each of said plurality of remote stations, said method comprising the steps of: defining a sequence of time frames during which messages and data are transmitted over said shared medium, each said time frame being divided into at least three types of time slots, a type A time slot for outbound transmission from said base station to said plurality of remote stations, a type B time slots for contention free inbound transmission from said plurality of remote stations to said base station and a type C time slots for contention access by said plurality of remote stations for transmission over said shared medium; allocating in a given time frame a variable number of said type A, type B and type C slots; and interleaving within said given time frame groups of consecutive slots of the same type.
Claim 22
Independent Claim
183 words
A medium access control method in a digital communication system of the type comprising a plurality of remote stations, each including a transceiver for communication over a shared medium and a base station having a transceiver for communication over said shared medium with the transceivers of each of said plurality of remote stations, said method comprising the steps of: defining a sequence of time frames during which messages and data are transmitted over said shared medium, each said time frame being divided into at least three types of time slots, a type A time slot for outbound transmission from said base station to said plurality of remote stations, a type B time slots for contention free inbound transmission from said plurality of remote stations to said base station and a type C time slots for contention access by said plurality of remote stations for transmission over said shared medium; allocating in a given time frame a variable number of said type A, type B and type C slots; and interleaving within said given time frame groups of consecutive slots of the same type.
Claim 23
Dependent Claim
48 words
The method of claim 20 wherein said base station's and said remote stations' transceivers use frequency hopping radio signaling with said shared medium being a radio frequency channel and wherein said method includes the step of: spreading said given time frame over one or more frequency hopping periods.
Claim 24
Dependent Claim
22 words
The method of claim 21 further comprising the step of: inserting in said given time frame a frequency hopping type time slot.
Claim 25
Dependent Claim
32 words
The method of claim 20 wherein the step of interleaving includes inserting at least one type C slot after each group of type A slots and each group of type B slots.
Claim 26
Dependent Claim
36 words
The method of claim 23 wherein the step of interleaving type A, type B and type C periods within said time frame includes inserting a type C period at the end of said given time frame.
Claim 27
Dependent Claim
81 words
The method claim 24 wherein said step of allocating said time slots comprises the steps of: queuing outbound transmission requests in a first queue and queuing inbound transmission requests in a second queue; dequeuing one or more pending requests from either said first queue or said second queue; and assigning a given period in said time frame to said one or more pending requests, said given period being type A for outbound transmission requests and type B for inbound transmissions requests.
Claim 28
Dependent Claim
28 words
The method of claim 25 wherein said dequeuing step includes alternatively dequeuing one or more pending requests from respectively said first queue and said second queue in sequence.
Claim 29
Dependent Claim
47 words
The method of claim 25 wherein said dequeuing step includes dequeuing in sequence one or more pending requests from said first queue, respectively said second queue, if said second queue, respectively said first queue is empty, until the duration of said given periods exceeds a predetermined value.
Claim 30
Dependent Claim
31 words
The method of claim 27 wherein said interleaving step includes limiting the total number of successive type A, B and C periods in each said time frame to a predetermined value.
Claim 31
Dependent Claim
43 words
The method of claim 20 further including the step of 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 type C slots.
Claim 32
Dependent Claim
60 words
The method of claim 29 further including the steps of: providing an indication in a transmission from each said remote station to said base station of whether a given transmission of data is a retransmission; and computing said control indicia as a function of said indications in transmissions from each said remote station over one or more said time frames.
Claim 33
Dependent Claim
19 words
The method of claim 30 wherein said step of computing said control indicia is performed for each time frame.
Claim 34
Dependent Claim
32 words
The method of claim 31 wherein said step of computing said control includes computing said indicia as a function of an estimate of the number of said remote stations contending for access.
Claim 35
Dependent Claim
50 words
The method of claim 32 wherein said step of computing said control indicia include computing said control indicia as a function of the ratio of the number of C slots in which a successful transmission from one of said remote stations occurs, relative to the total number of C slots.
Claim 36
Dependent Claim
65 words
The method of claim 33 wherein said step of computing said control indicia includes computing said control indicia as a function of the ratio of the number of C slots in which said remote stations succeeded on a first attempt to transmit to said base station relative to the total number of remote stations that succeeded in an attempt to transmit to said base station.
Claim 37
Dependent Claim
28 words
The method of claim 20 wherein said type C slots are dedicated to contention access by said plurality of remote stations for inbound transmission to said base station.
References Cited (Backward Citations)
US4907224A
Cited
US5142534A
Cited
US5123029A
Cited
US5241542A
Cited
CA2115211A1
Cited
US5384777A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-06-30 | 2000-12-30 | 2001-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-06-30 | 2004-12-30 | 2005-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-06-30 | 2008-12-30 | 2009-07-01 | $7700.00 | Window Closed / Lapsed |