US5353302A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Signal despreader for CDMA systems
Assignee: Nokia Bell Labs
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Filing: 1993-02-03
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Granted: 1994-10-04
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Expires: 2013-02-03
Abstract
Abstract A signal despreader for use in a CDMA system processes samples of the received signal with filtered replicas of the code coefficient sequences associated with the system users. The symbols transmitted by each system user are recovered using a filtered replica of that user's associated code coefficient sequence. In the disclosed embodiment, the communications channel between each system user's transmitter and the base station is bandlimited. Accordingly, within each user's transmitter, filtering apparatus having a frequency characteristic is utilized to limit the frequency spectrum of each coded signal to a predetermined bandwidth equal to or less than that of the communications channel. Each filtered replica, pursuant to the present invention, reflects this frequency characteristic. In addition, the communications channel also has a frequency characteristic, and each filtered replica can reflect this characteristic as well.
Inventors
- 👤 Qi Bi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:57
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/69; H04B1/707
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
113 words
In a CDMA system which transmits a coded signal for each of a plurality of users through a bandlimited channel, each coded user signal being formed by processing that user's symbols using a sequence of code coefficients, said sequence being different for each user, and wherein a received signal includes a composite of all coded user signals, apparatus comprising: means for receiving samples of said received signal; means for forming a filtered replica of each sequence of code coefficients: and means for estimating a user's symbols in response to said received signal samples and in response to said filtered replica of the sequence of code coefficients used to from this user's coded signal.
Claim 2
Dependent Claim
113 words
In a CDMA system which transmits a coded signal for each of a plurality of users through a bandlimited channel, each coded user signal being formed by processing that user's symbols using a sequence of code coefficients, said sequence being different for each user, and wherein a received signal includes a composite of all coded user signals, apparatus comprising: means for receiving samples of said received signal; means for forming a filtered replica of each sequence of code coefficients: and means for estimating a user's symbols in response to said received signal samples and in response to said filtered replica of the sequence of code coefficients used to from this user's coded signal.
Claim 3
Dependent Claim
32 words
The apparatus of claim 1 wherein the processing to form each coded user signal utilizes means which provides a first transfer function and said estimating means also provides said first transfer function.
Claim 4
Dependent Claim
24 words
The apparatus of claim 1 wherein said bandlimiting channel provides a second transfer function and said estimating means also provides said second transfer function.
Claim 5
Dependent Claim
28 words
The apparatus of claim 3 wherein said estimating means provides a third transfer function equal to a product of said first transfer function and said second transfer function.
Claim 6
Dependent Claim
24 words
The apparatus of claim 1 wherein said bandlimiting channel provides a second transfer function and said estimating means also provides said second transfer function.
Claim 7
Dependent Claim
35 words
The apparatus of claim 1 wherein said sequence of code coefficients is a pseudorandom sequence and the processing to form a coded user signal from that user's symbols includes means for providing said pseudorandom sequence.
Claim 8
Dependent Claim
54 words
The apparatus of claim 1 wherein each coded signal has a finite set of signal values and said estimating means includes means for generating said finite set of signal values and means for processing said finite set of signal values, said processing means being responsive to said received signal samples and said filtered replica.
Claim 9
Dependent Claim
37 words
The apparatus of claim 7 wherein said processing means provides a processed finite set of signal values and said estimating means further includes means for selecting one signal value from said processed finite set of signal values.
Claim 10
Dependent Claim
110 words
In a CDMA system which transmits a coded signal for each of a plurality of users through a bandlimited channel, each coded user signal being formed by processing that user's symbols using a sequence of code coefficients which is different for each user and wherein a received signal includes a composite of all coded user signals, a method comprising the steps of: receiving samples of said received signal; forming a filtered replica of each sequence of code coefficients: and estimating a user's symbols in response to said received signal samples and in response to said filtered replica of the sequence of code coefficients used to form this user's coded signal.
Claim 11
Dependent Claim
110 words
In a CDMA system which transmits a coded signal for each of a plurality of users through a bandlimited channel, each coded user signal being formed by processing that user's symbols using a sequence of code coefficients which is different for each user and wherein a received signal includes a composite of all coded user signals, a method comprising the steps of: receiving samples of said received signal; forming a filtered replica of each sequence of code coefficients: and estimating a user's symbols in response to said received signal samples and in response to said filtered replica of the sequence of code coefficients used to form this user's coded signal.
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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) | 1997-10-03 | 1998-04-04 | 1998-10-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-03 | 2002-04-04 | 2002-10-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-10-03 | 2006-04-04 | 2006-10-04 | $7700.00 | Window Closed / Lapsed |