US5809061A
Expired / Lapsed
US
⏱️ 0.0 years remaining
CDMA communication system with pilot tone control
Assignee: Sigtek Inc
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Filing: 1995-08-14
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Granted: 1998-09-15
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Expires: 2015-08-14
Abstract
Abstract A method and apparatus for the control of each mobile station within a Code Division Multiple Access (CDMA) communications network using simple pilot tones generated and controlled by a base station is described that is intended for use with full duplex, point to multipoint communications networks, particularly low mobility, cellular configurations. A pilot tone signal is added to a voice channel transmitted from a base station to a mobile station. The voice and pilot tone signals are further modulated using direct sequence spread spectrum (DSSS) techniques. The pilot tone serves several purposes. It allows the receive hardware to recover a frequency reference based on the DSSS code rate, which is used to synthesize the receiver tuning, generate the DSSS decoding sequence and synchronously demodulate the voice channel at the mobile station. The amplitude of the forward channel pilot tone is used to control the return channel transmit level. The invention implements a combined open and closed loop mechanism. The pilot tone is always present during voice activity detection and allows immediate activation of the voice channel with proper tuning and power level.
Inventors
- 👤 James E. Shea
- 👤 Royce G. Bunce
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:26
CPC Classifications
H; H04; H04W; H04W52/00; H04W52/04; H04W52/06; H04B; H04B1/00; H04B1/69; H04B1/707; H04B7/00; H04B7/24; H04B7/26; H04B7/2628; H04B7/2637
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
251 words
A communication system comprising: a base station including a base station transmitter and a base station receiver, wherein the base station transmitter comprises channel modulation means for receiving a base station input signal and generating a modulated channel signal, pilot tone generation means for generating a pilot tone signal, direct sequence spread spectrum modulation means for receiving the modulated channel signal from the channel modulation means and the pilot tone signal from the pilot tone generation means and direct sequence spread spectrum modulating said modulated channel signal and said pilot tone signal to generate a direct sequence spread spectrum modulated channel signal and a direct sequence spread spectrum modulated pilot tone signal, and means for transmitting the direct sequence spread spectrum modulated channel signal and the direct sequence spread spectrum modulated pilot tone signal; and at least one mobile station including a mobile station receiver and a mobile station transmitter, wherein the mobile station receiver comprises means for receiving the direct sequence spread spectrum modulated channel signal and the direct sequence spread spectrum modulated pilot tone signal from the base station, a direct sequence spread spectrum demodulator for direct sequence spread spectrum demodulating the received direct sequence spread spectrum modulated channel signal and the received direct sequence spread spectrum modulated pilot tone signal to generate a direct sequence spread spectrum demodulated channel signal and a direct sequence spread spectrum demodulated pilot tone signal, and channel demodulation means for generating a recovered signal from the direct sequence spread spectrum demodulated channel signal.
Claim 2
Dependent Claim
251 words
A communication system comprising: a base station including a base station transmitter and a base station receiver, wherein the base station transmitter comprises channel modulation means for receiving a base station input signal and generating a modulated channel signal, pilot tone generation means for generating a pilot tone signal, direct sequence spread spectrum modulation means for receiving the modulated channel signal from the channel modulation means and the pilot tone signal from the pilot tone generation means and direct sequence spread spectrum modulating said modulated channel signal and said pilot tone signal to generate a direct sequence spread spectrum modulated channel signal and a direct sequence spread spectrum modulated pilot tone signal, and means for transmitting the direct sequence spread spectrum modulated channel signal and the direct sequence spread spectrum modulated pilot tone signal; and at least one mobile station including a mobile station receiver and a mobile station transmitter, wherein the mobile station receiver comprises means for receiving the direct sequence spread spectrum modulated channel signal and the direct sequence spread spectrum modulated pilot tone signal from the base station, a direct sequence spread spectrum demodulator for direct sequence spread spectrum demodulating the received direct sequence spread spectrum modulated channel signal and the received direct sequence spread spectrum modulated pilot tone signal to generate a direct sequence spread spectrum demodulated channel signal and a direct sequence spread spectrum demodulated pilot tone signal, and channel demodulation means for generating a recovered signal from the direct sequence spread spectrum demodulated channel signal.
Claim 3
Dependent Claim
54 words
A communication system as claimed in claim 1, wherein the mobile station receiver further comprises a power measurement means for measuring a power level of the direct sequence spread spectrum demodulated pilot tone signal and generating a power control signal that is supplied to the mobile station transmitter to normalize return channel transmit levels.
Claim 4
Dependent Claim
40 words
A communication system as claimed in claim 1, wherein the base station transmitter further comprises frequency reference generation means for generating a reference signal that is supplied to the channel modulation means and the direct sequence spread spectrum modulation means.
Claim 5
Dependent Claim
41 words
A communication system as claimed in claim 3, wherein the pilot tone signal is direct sequence spread spectrum modulated by the direct sequence spread spectrum modulation means with a direct sequence spread spectrum code at a rate of the reference signal.
Claim 6
Dependent Claim
34 words
A communication system as claimed in claim 1, wherein the base station transmitter continues to generate and transmit the direct sequence spread spectrum modulated pilot tone signal when the input signal is not present.
Claim 7
Dependent Claim
39 words
A communication system as claimed in claim 4, wherein the mobile station receiver further comprises a voltage controlled crystal oscillator that provides a local reference signal to the direct sequence spread spectrum demodulating means and the channel demodulation means.
Claim 8
Dependent Claim
32 words
A communication system as claimed in claim 6, wherein the voltage controlled crystal oscillator is locked based on a code lock error signal supplied by the direct sequence spread spectrum demodulating means.
Claim 9
Dependent Claim
126 words
A communication system as claimed in claim 1, wherein the mobile station transmitter comprises channel modulation means for receiving a mobile station input signal and generating a modulated channel signal, pilot tone generation means for generating a fixed pilot tone signal, direct sequence spread spectrum modulation means for receiving the modulated channel signal from the channel modulation means and the pilot tone signal from the pilot tone generation means and direct sequence spread spectrum modulating said modulated channel signal and said pilot tone signal to generate a direct sequence spread spectrum modulated channel signal and a direct sequence spread spectrum modulated pilot tone signal, and means for transmitting the direct sequence spread spectrum modulated channel signal and the direct sequence spread spectrum modulated pilot tone signal.
Claim 10
Dependent Claim
109 words
A communication system as claimed in claim 1, wherein the base station receiver comprises means for receiving the direct sequence spread spectrum modulated channel signal and the direct sequence spread spectrum modulated pilot tone signal from the mobile station, a direct sequence spread spectrum demodulator for direct sequence spread spectrum demodulating the received direct sequence spread spectrum modulated channel signal and the received direct sequence spread spectrum modulated pilot tone signal to generate a direct sequence spread spectrum demodulated channel signal and a direct sequence spread spectrum demodulated pilot tone signal, and channel demodulation means for generating a recovered signal from the direct sequence spread spectrum demodulated channel signal.
Claim 11
Dependent Claim
53 words
A communication system as claimed in claim 9, wherein the base station receiver further comprises a power measurement means for measuring a power level of the direct sequence spread spectrum demodulated pilot tone signal and generating a control signal that is supplied to the pilot tone generation means of the base station transmitter.
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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) | 2001-09-14 | 2002-03-16 | 2002-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-09-14 | 2006-03-16 | 2006-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-09-14 | 2010-03-16 | 2010-09-15 | $7700.00 | Window Closed / Lapsed |