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US5825835A
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Multi-user acquisition procedure for multipoint-to-point synchronous CDMA systems
Assignee: L3 Technologies Inc
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Filing: 1996-02-23
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Granted: 1998-10-20
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Expires: 2016-02-23
Abstract
Abstract Disclosed are methods and apparatus for use in a synchronous CDMA communications system (10) that employs orthogonal pn spreading codes. The methods are intended for synchronizing transmissions from a subscriber unit (SU 14) to a radio base unit (RBU 12), and include the steps of: (a) transmitting individual ones of a plurality of bursts from the SU to the RBU, each burst being transmitted with a different pn spreading code timing alignment; (b) receiving individual ones of the plurality of bursts with the RBU and determining a power estimate of each received burst; and (c) in response to a determined power estimate of one of the bursts exceeding a threshold, sending a message from the RBU to the SU. The message indicates that the SU is to use for subsequent transmissions the pn spreading code timing alignment that was employed when transmitting the burst that exceeded the threshold. In a preferred embodiment of this invention the step of transmitting transmits an indication of the pn spreading code timing alignment used when transmitting a given one of the bursts. Each burst is transmitted with a pn spreading code timing alignment that differs by 1/2 chip from a previous pn spreading code timing alignment.
Inventors
- 👤 Samuel C. Kingston
- 👤 Thomas R. Giallorenzi
- 👤 Robert William Steagall
- 👤 David Matolak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:25
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7073; H04B1/7075; H04B1/7077; H04B1/7097; H04B1/7103; H04B2201/00; H04B2201/69; H04B2201/707; H04B2201/70707; H04B2201/7071; H04B2201/7097; H04B2201/709709; H04W; H04W92/00; H04W92/04; H04W92/10
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
144 words
In a synchronous CDMA communications system using orthogonal pn spreading codes, a method for synchronizing transmissions from a subscriber unit (SU) to a radio base unit (RBU), comprising the steps of: (a) transmitting individual ones of a plurality of bursts from the SU to the RBU, each burst being transmitted with a different pn spreading code timing alignment; (b) receiving individual ones of the plurality of bursts with the RBU and determining a power estimate of each received burst; and (c) in response to a determined power estimate of one of the bursts exceeding a threshold, initiating the synchronization of subsequent transmissions from the SU by sending a message from the RBU to the SU, the message indicating that the SU is to use for the subsequent transmissions the pn spreading code timing alignment that was employed when transmitting the one of the bursts.
Claim 2
Dependent Claim
144 words
In a synchronous CDMA communications system using orthogonal pn spreading codes, a method for synchronizing transmissions from a subscriber unit (SU) to a radio base unit (RBU), comprising the steps of: (a) transmitting individual ones of a plurality of bursts from the SU to the RBU, each burst being transmitted with a different pn spreading code timing alignment; (b) receiving individual ones of the plurality of bursts with the RBU and determining a power estimate of each received burst; and (c) in response to a determined power estimate of one of the bursts exceeding a threshold, initiating the synchronization of subsequent transmissions from the SU by sending a message from the RBU to the SU, the message indicating that the SU is to use for the subsequent transmissions the pn spreading code timing alignment that was employed when transmitting the one of the bursts.
Claim 3
Dependent Claim
36 words
A method as set forth in claim 1, wherein the step of transmitting includes a step of transmitting an indication of the pn spreading code timing alignment used when transmitting each of the plurality of bursts.
Claim 4
Dependent Claim
110 words
A method as set forth in claim 1 wherein the step of receiving includes the steps of: summing M samples per chip to obtain a first result; despreading the first result; summing L chips per symbol from the first result to obtain a second result; summing a plurality of symbols from the second result to obtain a power estimate of a current pn spreading code timing alignment that was transmitted by the SU; obtaining an averaged power estimate that includes a power estimate from a previous pn spreading code alignment for forming the threshold; and comparing the power estimate of the current pn spreading code timing alignment to the threshold.
Claim 5
Dependent Claim
42 words
A method as set forth in claim 1, wherein in response to the SU exhausting a predetermined range of permissible pn spreading code timing alignments, performing the steps of increasing an output power of an SU transmitter, and re-executing the steps (a)-(c).
Claim 6
Dependent Claim
33 words
A method as set forth in claim 1, wherein each burst is transmitted with a pn spreading code timing alignment that differs by 1/2 chip from a previous pn spreading code timing alignment.
Claim 7
Dependent Claim
43 words
A method as set forth in claim 1, wherein each transmitted burst is separated by a period of no transmission by the SU, and further comprising a step of also determining a power estimate during the period of no transmission by the SU.
Claim 8
Dependent Claim
125 words
A method as set forth in claim 1, and further comprising the steps of: in response to the RBU sending the message, changing the pn spreading code timing alignment by a predetermined number of chips; transmitting individual ones of a second plurality of bursts from the SU to the RBU, each burst being transmitted with a different pn spreading code timing alignment; receiving the second plurality of bursts in RBU and storing, for each received burst, a corresponding magnitude of a pn correlation value; and after receiving a predetermined number of the second bursts, transmitting a message to the SU, the message instructing the SU to use for subsequent transmissions a pn spreading code timing alignment that corresponds to a largest stored pn correlation value.
Claim 9
Dependent Claim
121 words
In a synchronous CDMA communications system using orthogonal pn spreading codes, a method for synchronizing transmissions from a subscriber unit (SU) to a radio base unit (RBU), comprising the steps of: transmitting individual ones of a plurality of bursts from the SU to the RBU, each burst being transmitted with a different pn spreading code timing alignment; receiving the plurality of bursts in the RBU and storing, for each received burst, a corresponding magnitude of a pn correlation value; and after receiving a predetermined number of the plurality of bursts, sending a message to the SU, the message instructing the SU to use for subsequent transmissions a pn spreading code timing alignment that corresponds to a largest stored pn correlation value.
Claim 10
Dependent Claim
121 words
In a synchronous CDMA communications system using orthogonal pn spreading codes, a method for synchronizing transmissions from a subscriber unit (SU) to a radio base unit (RBU), comprising the steps of: transmitting individual ones of a plurality of bursts from the SU to the RBU, each burst being transmitted with a different pn spreading code timing alignment; receiving the plurality of bursts in the RBU and storing, for each received burst, a corresponding magnitude of a pn correlation value; and after receiving a predetermined number of the plurality of bursts, sending a message to the SU, the message instructing the SU to use for subsequent transmissions a pn spreading code timing alignment that corresponds to a largest stored pn correlation value.
Claim 11
Dependent Claim
36 words
A method as set forth in claim 8, wherein the step of transmitting includes a step of transmitting an indication of the pn spreading code timing alignment used when transmitting each of the plurality of bursts.
Claim 12
Dependent Claim
33 words
A method as set forth in claim 8, wherein each burst is transmitted with a pn spreading code timing alignment that differs by 1/2 chip from a previous pn spreading code timing alignment.
Claim 13
Dependent Claim
157 words
A synchronous CDMA communications system using orthogonal pn spreading codes, said synchronous CDMA communications system comprising at least one subscriber unit (SU) and at least one radio base unit (RBU), said synchronous CDMA communications system further comprising apparatus for synchronizing transmission from the SU to the RBU, said apparatus being comprised of: means in said SU for transmitting individual ones of a plurality of bursts to the RBU, each burst being transmitted with a different pn spreading code timing alignment; means in said RBU for receiving individual ones of the plurality of bursts and for determining a power estimate of each received burst; and means, responsive to a determined power estimate of one of the bursts exceeding a threshold, for sending a message from the RBU to the SU, the message indicating that the SU is to use for subsequent transmissions the pn spreading code timing alignment that was employed when transmitting the one of the bursts.
Claim 14
Dependent Claim
157 words
A synchronous CDMA communications system using orthogonal pn spreading codes, said synchronous CDMA communications system comprising at least one subscriber unit (SU) and at least one radio base unit (RBU), said synchronous CDMA communications system further comprising apparatus for synchronizing transmission from the SU to the RBU, said apparatus being comprised of: means in said SU for transmitting individual ones of a plurality of bursts to the RBU, each burst being transmitted with a different pn spreading code timing alignment; means in said RBU for receiving individual ones of the plurality of bursts and for determining a power estimate of each received burst; and means, responsive to a determined power estimate of one of the bursts exceeding a threshold, for sending a message from the RBU to the SU, the message indicating that the SU is to use for subsequent transmissions the pn spreading code timing alignment that was employed when transmitting the one of the bursts.
Claim 15
Dependent Claim
31 words
A system as set forth in claim 11, wherein said transmitting means transmits an indication of the pn spreading code timing alignment used when transmitting each of the plurality of bursts.
Claim 16
Dependent Claim
121 words
A system as set forth in claim 11 wherein said receiving means is comprised of: means for summing M samples per chip to obtain a first result; means for despreading the first result; means for summing L chips per symbol from the first result to obtain a second result; means for summing a plurality of symbols from the second result to obtain a power estimate of a current pn spreading code timing alignment that was transmitted by the SU; means for obtaining a scaled averaged power estimate that includes a power estimate from a previous pn spreading code alignment for forming the threshold; and means for comparing the power estimate of the current pn spreading code timing alignment to the threshold.
Claim 17
Dependent Claim
53 words
A system as set forth in claim 11, wherein in response to the SU exhausting a predetermined range of permissible pn spreading code timing alignments, said SU further comprises means for increasing an output power of transmitter of the SU, and for re-transmitting individual ones of the plurality of bursts to the RBU.
Claim 18
Dependent Claim
33 words
A system as set forth in claim 11, wherein each burst is transmitted with a pn spreading code timing alignment that differs by 1/2 chip from a previous pn spreading code timing alignment.
Claim 19
Dependent Claim
23 words
A system as set forth in claim 11, wherein each transmitted burst is separated by a period of no transmission by the SU.
Claim 20
Dependent Claim
135 words
A system as set forth in claim 11, and further comprising: means in said SU, responsive to the RBU sending the message, for changing the pn spreading code timing alignment by a predetermined number of chips; means for transmitting individual ones of a second plurality of bursts to the RBU, each burst being transmitted with a different pn spreading code timing alignment; means in said RBU for receiving the second plurality of bursts and for storing, for each received burst, a corresponding magnitude of a pn correlation value; and means in said RBU, responsive to receiving a predetermined number of the second bursts, for transmitting a message to the SU, the message instructing the SU to use for subsequent transmissions a pn spreading code timing alignment that corresponds to a largest stored pn correlation value.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-10-19 | 2002-04-20 | 2002-10-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-19 | 2006-04-20 | 2006-10-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-19 | 2010-04-20 | 2010-10-20 | $7700.00 | Window Closed / Lapsed |