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US4726038A
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Digital communication system
Assignee: FUMIO IKEGAMI
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Filing: 1985-08-22
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Granted: 1988-02-16
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Expires: 2005-08-22
Abstract
Abstract The present invention provides a communication system which employs a signal whose carrier phase is shifted by a constant amount Δθ per time slot in correspondence to each symbol (1 or 0) transmitted, and the phase shift is performed by Δθ/2 (or -Δθ/2) in the first 1/2 time slot and further by Δθ/2 (or -Δθ/2) in the second 1/2 time slot thereby to improve the bit error rate in multipath propagation.
Inventors
- 👤 Fumio Ikegami
- 👤 Susumu Yoshida
- 👤 Tsutomu Takeuchi
- 👤 Sirikiat Ariyavisitakul
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:45
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/18; H04L27/22; H04L27/233; H04L27/2331; H04L27/20; H04L27/2032; H04L27/2053; H04L27/206; H04L27/2067; H04L27/2085
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
192 words
A digital communication system for transmitting binary information symbols, including a first information symbol and a second information symbol, through a transmission medium formed by a multipath channel wherein each path has a substantially different transmission time, the digital communication system being capable of improving symbols comprising: transmitting means for generating and transmitting through said transmission medium a phase shift keyed transmission signal which, in correspondence with the binary information symbols sent out at a predetermined time slot, shifts a phase of an information signal by Δθ/2 for each 1/2 time slot two times in succession for said first information symbol, and shifts the phase by -Δθ/2 for each 1/2 time slot two times in succession for the other information symbol; receiving means for receiving the transmitted signal transmitted through said transmission medium; and demodulating means for dividing a signal received by said receiving means into two signals delaying, by 1/2 time slot, one of the two signals to obtain a delayed signal, multiplying the delayed signal by the other one of said two signals to obtain a product signal and integrating said product signal to obtain the original binary information symbol.
Claim 2
Dependent Claim
192 words
A digital communication system for transmitting binary information symbols, including a first information symbol and a second information symbol, through a transmission medium formed by a multipath channel wherein each path has a substantially different transmission time, the digital communication system being capable of improving symbols comprising: transmitting means for generating and transmitting through said transmission medium a phase shift keyed transmission signal which, in correspondence with the binary information symbols sent out at a predetermined time slot, shifts a phase of an information signal by Δθ/2 for each 1/2 time slot two times in succession for said first information symbol, and shifts the phase by -Δθ/2 for each 1/2 time slot two times in succession for the other information symbol; receiving means for receiving the transmitted signal transmitted through said transmission medium; and demodulating means for dividing a signal received by said receiving means into two signals delaying, by 1/2 time slot, one of the two signals to obtain a delayed signal, multiplying the delayed signal by the other one of said two signals to obtain a product signal and integrating said product signal to obtain the original binary information symbol.
Claim 3
Dependent Claim
18 words
A digital communication system in accordance with claim 1, wherein said multipath channel is a multipath fading channel.
Claim 4
Dependent Claim
21 words
A digital communication system in accordance with claim 1, wherein the phase shift for each said 1/2 time slot is π/2.
Claim 5
Dependent Claim
21 words
A digital communication system in accordance with claim 1, wherein the phase shift for each said 1/2 time slot is π/4.
Claim 6
Dependent Claim
22 words
A digital communication system in accordance with claim 1, wherein the phase shift for each said 1/2 time slot is 110 degrees.
Claim 7
Dependent Claim
28 words
A digital communication system in accordance with any one of claims 3 through 5, wherein the phase shift for each said 1/2 slot occurs in a stepped manner.
Claim 8
Dependent Claim
32 words
A digital communication system in accordance with any one of claims 1, 2, or 3, wherein said phase shift for each said 1/2 time slot is defined by a raised cosine function.
Claim 9
Dependent Claim
179 words
In a digital communication system for transmitting binary information symbols, including a first information symbol and a second information symbol, through a transmission medium formed by a multipath channel wherein each path has a substantially different transmission time, a method of improving bit error rate, comprising the steps of: transmitting through said medium a phase shift keyed transmission signal which, in correspondence with the binary information symbols sent out at a predetermined time slot, shifts a phase of an information signal by Δθ/2 for each one-half time slot two times in succession for said first information symbol, and shifts the phase by -Δθ/2 for each one-half time slot two times in succession for the other information symbol; receiving the transmitted signal; dividing a received signal into two signals; and delaying by one-half time slot, one of said two signals to obtain a delayed signal, multiplying the delayed signal by the other one of said two signals to obtain a product signal and integrating said product signal to obtain the original binary information symbol having an improved bit error rate.
Claim 10
Dependent Claim
179 words
In a digital communication system for transmitting binary information symbols, including a first information symbol and a second information symbol, through a transmission medium formed by a multipath channel wherein each path has a substantially different transmission time, a method of improving bit error rate, comprising the steps of: transmitting through said medium a phase shift keyed transmission signal which, in correspondence with the binary information symbols sent out at a predetermined time slot, shifts a phase of an information signal by Δθ/2 for each one-half time slot two times in succession for said first information symbol, and shifts the phase by -Δθ/2 for each one-half time slot two times in succession for the other information symbol; receiving the transmitted signal; dividing a received signal into two signals; and delaying by one-half time slot, one of said two signals to obtain a delayed signal, multiplying the delayed signal by the other one of said two signals to obtain a product signal and integrating said product signal to obtain the original binary information symbol having an improved bit error rate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-02-15 | 1991-08-17 | 1992-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-15 | 1995-08-17 | 1996-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-15 | 1999-08-17 | 2000-02-16 | $7700.00 | Window Closed / Lapsed |