US3649764A
Expired / Lapsed
US
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Variable burst length tdma system
Assignee: International Telecommunications Satellite Organization
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Filing: 1969-10-15
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Granted: 1972-03-14
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Expires: 1989-10-15
Abstract
Abstract In a time division multiple-access communications system using a satellite transponder and a plurality of earth stations, each earth station periodically transmits bursts of data which are timed so that the bursts from the earth stations in the system interleave and do not overlap in time when received at the satellite. The total time for transmitting one burst from all stations is the frame time of the system. Each burst is subdivided into numerous time slots or channels during which digital information, such as digitally coded voice communications, is transmitted. All slots or channels which are allocated at any given time to a particular station may be occupied (i.e. the station actually transmits information during the time slot) or only some of the slots may be occupied, depending upon the traffic from the station. Periodically, or in response to actual traffic conditions, each station transmits an indication of its highest numbered channel then in use. The remaining or slack channels for all stations are totaled and divided up equally among all of the operating stations in the frame. Burst movement to accommodate the reallocation of channels is accomplished serially, one burst at a time. Since the slack channels are at the end of the bursts, the nonuse of the slack channels effectively shortens each burst. Burst B moves forward to bunch up against burst A, burst C then moves forward to bunch up against burst B, etc. After the calculations with respect to total slack time have been performed and each station calculates its burst position relative to the reference station to accommodate its new allocation of channels, serial movement of the bursts takes place in a direction away from the reference burst, i.e., the last burst in the frame moves back to the proper position followed by the second to last burst, etc.
Inventors
- 👤 Wilfrid G Maillet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 05:17
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/204; H04B7/212; H04B7/2125
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
405 words
In a TDMA communications system of the type having the following characteristics: multiple operating stations; each station transmits a burst of data in a nonoverlapping time sequence with respect to the burst from the other stations and receives all station bursts; a complete sequence of one burst from each station makes up the system frame time, the first burst in the frame being a reference burst; each burst includes a preamble identifying the transmitting station and a plurality of information channels allocated to the station, each of which may be filled or not filled with information; and each station has a burst synchronizer which maintains the time separation between the local station burst and the reference station burst equal to an amount dependent upon the quantity in a burst synchronizer delay counter; the improvement comprising, at a local station, a. means responsive to a reallocation code in any received burst for transmitting during the local station bursts, an indication of the last channel presently in use at said local station, those unused channels higher than said last channel being slack channels b. timing means for generating timing pulses representing a first and second series of nonoverlapping time periods, c. means responsive to laSt channel indications in the received bursts from all stations for altering the contents of said delay counter during a said first series time period dependent upon the position of the local station burst in a frame, to move the local station burst forward an amount of time equivalent to the sum of the slack channels in all preceding bursts in the frame, d. slack channel calculating means responsive to said last channel indications, for calculating a number of slack channels to be allocated to each station, and e. means responsive to said calculated number of slack channels for altering the contents of said delay counter during a said second series time period dependent upon the position of the local station burst in a frame, to move the local station burst backward an amount of time equivalent to the sum of slack channels allocated to all prior bursts by said calculating means, whereby the start times of successive ones of said time periods are separated by a sufficient amount of time to allow complete burst movement and whereby the bursts are moved serially forward starting with the burst nearest the reference and then serially backward starting with the burst farthest from the reference.
Claim 2
Dependent Claim
405 words
In a TDMA communications system of the type having the following characteristics: multiple operating stations; each station transmits a burst of data in a nonoverlapping time sequence with respect to the burst from the other stations and receives all station bursts; a complete sequence of one burst from each station makes up the system frame time, the first burst in the frame being a reference burst; each burst includes a preamble identifying the transmitting station and a plurality of information channels allocated to the station, each of which may be filled or not filled with information; and each station has a burst synchronizer which maintains the time separation between the local station burst and the reference station burst equal to an amount dependent upon the quantity in a burst synchronizer delay counter; the improvement comprising, at a local station, a. means responsive to a reallocation code in any received burst for transmitting during the local station bursts, an indication of the last channel presently in use at said local station, those unused channels higher than said last channel being slack channels b. timing means for generating timing pulses representing a first and second series of nonoverlapping time periods, c. means responsive to laSt channel indications in the received bursts from all stations for altering the contents of said delay counter during a said first series time period dependent upon the position of the local station burst in a frame, to move the local station burst forward an amount of time equivalent to the sum of the slack channels in all preceding bursts in the frame, d. slack channel calculating means responsive to said last channel indications, for calculating a number of slack channels to be allocated to each station, and e. means responsive to said calculated number of slack channels for altering the contents of said delay counter during a said second series time period dependent upon the position of the local station burst in a frame, to move the local station burst backward an amount of time equivalent to the sum of slack channels allocated to all prior bursts by said calculating means, whereby the start times of successive ones of said time periods are separated by a sufficient amount of time to allow complete burst movement and whereby the bursts are moved serially forward starting with the burst nearest the reference and then serially backward starting with the burst farthest from the reference.
Claim 3
Dependent Claim
144 words
The apparatus claimed in claim 1 wherein said means for altering the contents of said delay counter during a said first series time period comprises; a. means for detecting the position of said local station burst within said frame, b. means for calculating the value BBi, where where P is a predetermined constant proportional to the preamble time of each burst; i is the number corresponding to the position of the local station burst within the frame; Cj is a number proportional to the time occupied by all but the slack channels in the burst in the jth position of said frame, and c. gating means responsive to said position detecting means and said timing pulses representing said first series of timing periods for entering said value BBi into said delay counter during the (i-1) time period of said first series of time periods.
Claim 4
Dependent Claim
104 words
The apparatus claimed in claim 2 wherein said means for altering the contents of said delay counter during a said second series time period comprises a. means for calculating the value BSi, where where Q is a number proportional to the time occupied by the slack channels calculated by said slack channel calculating means, and b. gating means responsive to said position-detecting means and said timing pulses representing said second series of timing periods for entering said value BSi into said delay counter during the (n-(i-1)) time period of said second series of time periods, wherein n is the number of bursts per frame.
Claim 5
Dependent Claim
88 words
The apparatus as claimed in claim 3 wherein said slack channel calculating means comprises, a. means responsive to said reallocation code for counting the number of bursts received during a time period equal to said frame period, b. means responsive to received last channel indications for calculating where Ct is a number representing the total channels per frame; n is the number of bursts per frame, and c. dividing means for calculating Q Cs/n, where Q is the number of slack channels to be allocated to each burst.
Claim 6
Dependent Claim
328 words
At a local station, the method of adjusting the transmit time of a burst of data to accommodate reallocation of data channels among several stations in a TDMA communications system of the type in which each station transmits one burst of data per frame, each burst containing signaling data and a number of data channels which may or may not be occupied with information, and in which each station receives the bursts from all other stations and synchronizes its own burst transmit time with a reference burst, the method comprising; a. detecting the presence of a predetermined code in a received burst, b. transmitting during the local station burst, a signal representing the burst time occupied by all said local station data channels up to and including the last data channel occupied with information, c. detecting said burst time signals in all received bursts, d. calculating the total slack time for the entire frame, said slack time for each burst being the burst time occupied by the data channels following said last data channel occupied with information, e. advancing the burst transmit time of said local station burst an amount of time equal to the slack time of all bursts in the frame which precede said local station burst, the step of advancing being accomplished during the (i-1) subtime period of a first time period, wherein i is an integer corresponding to the position of the local station burst in the frame, f. calculating the slack time to be allocated to each of the stations in the system, and g. retarding the burst transmit time of said local station burst an amount of time equal to the total slack time allocated to the bursts preceding the local station burst, the step of retarding being accomplished during the (n-(i-1)) subtime period of a second time period, wherein n is the number of bursts per frame and said second time period follows and does not overlap said first time period.
Claim 7
Dependent Claim
328 words
At a local station, the method of adjusting the transmit time of a burst of data to accommodate reallocation of data channels among several stations in a TDMA communications system of the type in which each station transmits one burst of data per frame, each burst containing signaling data and a number of data channels which may or may not be occupied with information, and in which each station receives the bursts from all other stations and synchronizes its own burst transmit time with a reference burst, the method comprising; a. detecting the presence of a predetermined code in a received burst, b. transmitting during the local station burst, a signal representing the burst time occupied by all said local station data channels up to and including the last data channel occupied with information, c. detecting said burst time signals in all received bursts, d. calculating the total slack time for the entire frame, said slack time for each burst being the burst time occupied by the data channels following said last data channel occupied with information, e. advancing the burst transmit time of said local station burst an amount of time equal to the slack time of all bursts in the frame which precede said local station burst, the step of advancing being accomplished during the (i-1) subtime period of a first time period, wherein i is an integer corresponding to the position of the local station burst in the frame, f. calculating the slack time to be allocated to each of the stations in the system, and g. retarding the burst transmit time of said local station burst an amount of time equal to the total slack time allocated to the bursts preceding the local station burst, the step of retarding being accomplished during the (n-(i-1)) subtime period of a second time period, wherein n is the number of bursts per frame and said second time period follows and does not overlap said first time period.
Claim 8
Dependent Claim
52 words
The method as claimed in claim 5 wherein the step of calculating the total slack time for the entire frame comprises a. subtracting amounts represented by said burst time signals from a predetermined number representing the total time per frame allocated to said data channels, the result being the total slack time.
Claim 9
Dependent Claim
66 words
The method as claimed in claim 6 wherein the step of calculating slack time to be allocated to each of the stations comprises, a. counting the number of received bursts during a period equal to a frame period, following receipt of said reallocation indication; b. dividing said total slack time by said counted number of received bursts, the quotient representing the slack channels allocated per station.
Claim 10
Independent Claim
185 words
A method of channel reallocation and burst movement for a TDMA communication system having multiple stations and a TDMA frame format of sequential nonoverlapping transmission bursts, one from each station, and each burst including multiple channels of data, the method comprising: a. transmitting from at least one station and receiving at all stations a reallocation initiate signal, b. during a first time period following reception of a reallocation initiate signal, sequentially moving forward in time beginning with the first burst subsequent to a reference burst, all bursts but the reference burst an amount of time equivalent to the sum of the slack channels in all preceding bursts, said slack channels corresponding to the consecutive channels at the end of each burst which do not contain data, c. allocating the total of said slack channels among the bursts, and d. during a second time period after said first time period, sequentially moving backward in time, beginning with the burst preceding the reference burst, all bursts but said reference burst an amount of time equivalent to the sum of the slack channels allocated to all preceding bursts.
Claim 11
Independent Claim
185 words
A method of channel reallocation and burst movement for a TDMA communication system having multiple stations and a TDMA frame format of sequential nonoverlapping transmission bursts, one from each station, and each burst including multiple channels of data, the method comprising: a. transmitting from at least one station and receiving at all stations a reallocation initiate signal, b. during a first time period following reception of a reallocation initiate signal, sequentially moving forward in time beginning with the first burst subsequent to a reference burst, all bursts but the reference burst an amount of time equivalent to the sum of the slack channels in all preceding bursts, said slack channels corresponding to the consecutive channels at the end of each burst which do not contain data, c. allocating the total of said slack channels among the bursts, and d. during a second time period after said first time period, sequentially moving backward in time, beginning with the burst preceding the reference burst, all bursts but said reference burst an amount of time equivalent to the sum of the slack channels allocated to all preceding bursts.
Claim 12
Dependent Claim
54 words
The method claimed in claim 8 further comprising the steps of, a. transmitting from each station, upon receipt of said reallocation initiate signal, a last channel signal representing the highest numbered channel at said station which is presently occupied with data, and b. detecting at each station the last channel signals from all stations.
Claim 13
Dependent Claim
46 words
The method claimed in claim 9 wherein the step of allocating comprises a. subtracting quantities represented by said last channel signals from a quantity representing the total channels per frame, b. dividing the resulT of the subtracting step by the number of bursts in a frame.
References Cited (Backward Citations)
US3517312A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-14 | 1975-09-13 | 1976-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-14 | 1979-09-13 | 1980-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-14 | 1983-09-13 | 1984-03-14 | $7700.00 | Window Closed / Lapsed |