CA2064975C
Expired / Lapsed
CA
⏱️ 0.0 years remaining
Method and apparatus for multiple access between transceivers in wireless communications using ofdm spread spectrum
Assignee: Individual
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Filing: 1992-03-27
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Granted: 1999-07-27
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Expires: 2012-03-27
Abstract
Abstract A method for allowing a number of wireless transceivers to exchange information (data, voice or video) with each other. A first frame of information is multiplexed over a number of wideband frequency bands at a first transceiver, and the information transmitted to a second transceiver. The information is received and processed at the second transceiver. The information is differentially encoded using phase shift keying. In addition, after a pre-selected time interval, the first transceiver may transmit again. During the preselected time interval, the second transceiver may exchange information with another transceiver in a time duplex fashion. The processing of the signal at the second transceiver may include estimating the phase differential of the transmitted signal and pre-distorting the transmitted signal. A transceiver includes an encoder for encoding information, a wideband frequency division multiplexer for multiplexing the information onto wideband frequency voice channels, and a local oscillator for upconverting the multiplexed information. The apparatus may include a processor for applying a Fourier transform to the multiplexed information to bring the information into the time domain for transmission.
Inventors
- 👤 Michel T. Fattouche
- 👤 Hatim Zagloul
Bibliographic Details
Application Number
—
Jurisdiction
CA
Data Source
google_patents
Last Synchronized
2026-10-26 05:56
CPC Classifications
—
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
209 words
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS: 1. A transceiver including a transmitter for transmitting electromagnetic signals and a receiver for receiving electromagnetic signals having amplitide and phase differential characteristics, the transmitter comprising: an encoder for encoding information; a wideband frequency division multiplexer for multiplexing the encoded information onto wideband frequency channels; a processor having an output for applying a Fourier transform to the multiplexed information to bring the information into the time domain for transmission; a low pass filter on the output from the processor; a local oscillator for upconverting the multiplexed information for transmission; and further including, in the receiver of the transceiver; a bandpass filter for filtering the received electromagnetic signals; a local oscillator for downconverting the received electromagnetic signals to produce output; a sampler for sampling the output of the local oscillator to produce sampled signals to the channel estimator; a channel estimator for estimating one or both of the amplitude and the phase differential of the received signals to produce as output one or both of an estimated amplitude and an estimated phase differential respectively; and 41 a decoder for producing signals from the sampled signals and the output from the channel estimator.
Claim 2
Dependent Claim
28 words
The transceiver of claim 1 further including, in the receiver of the transceiver: a deprocessor for applying an inverse Fourier transform to the samples output from the sampler.
Claim 3
Dependent Claim
35 words
The transceiver of claim 1, further including, in the receiver of the transceiver: a power controller before the sampler for monitoring the power of the received signal and for controlling the power of the signal.
Claim 4
Dependent Claim
46 words
The transceiver of claim 1, further including, in the transmitter of the transceiver: a pre-distorter before the processor, the pre-distorter being connected to the channel estimator, for predistorting a signal to be transmitted with one or both of the estimated amplitude or the estimated phase differential.
Claim 5
Dependent Claim
26 words
The transceiver of claim 4 in which the power controller is also connected to the pre-distorter for controlling the power of the signal to be transmitted.
Claim 6
Dependent Claim
26 words
The transceiver of claim 1 further including: means to modify the received signal with one or both of the estimated amplitude and phase differential respectively. 42
Claim 7
Independent Claim
108 words
A method for allowing a number of wireless transceivers to exchange frames of information, the method comprising the steps of: multiplexing a first frame of information over a number of frequencies within a frequency band at a first transceiver to produce multiplexed information; processing the multiplexed information at the first transceiver; transmitting the processed information to a second transceiver using a carrier frequency f c; receiving the processed information at the second transceiver; processing the processed information at the second transceiver during a first time interval; and the width of the frequency band being chosen so that neither carrier nor clock recovery is required at the second transceiver.
Claim 8
Dependent Claim
79 words
The method of claim 7 in which the frequency band is formed from a first set of K1 points and a pair of tail slots each having K2 points, each of the points being separated by a frequency range .DELTA.f, the second transceiver has a maximum expected clock error xT, where T is the duration of one time domain sample, the information is multiplexed over a number M of levels, and K1 is selected such that 2.pi.X/K1 < .pi./M.
Claim 9
Dependent Claim
27 words
The method of claim 8 further including transmitting a second frame of information from the second transceiver to the first transceiver within the same frequency band. 43
Claim 10
Dependent Claim
23 words
The method of claim 8 in which K2 is selected so that the out of band signal is less than a given level.
Claim 11
Dependent Claim
66 words
The method of claim 8 in which the first and second transceivers have an expected maximum relative velocity V, the first and second transceivers have carrier frequencies with a frequency offset from each other of f o, the carrier frequency has a corresponding travelling wavelength .lambda. and .DELTA.f is selected so that [V/(.lambda..DELTA.f) + f o/.DELTA.f] is less than or equal to a preselected sampling error.
Claim 12
Dependent Claim
38 words
The method of claim 8 in which processing the mutliplexed information at the second transceiver further includes calculating the mean of the phase shift due to sampling error by summing the estimated phase differential of the received signal.
Claim 13
Dependent Claim
33 words
The method of claim 12 in which the mean of the phase shift due to sampling error is divided by K1 and the result removed from the phase differential of the received signal.
Claim 14
Dependent Claim
96 words
A transmitter for transmitting electromagnetic signals having amplitide and phase differential characteristics, the transmitter comprising: an encoder for encoding information; a wideband frequency division multiplexer for multiplexing the encoded information onto wideband frequency channels; a processor having an output for applying a Fourier transform to the multiplexed information to 44 bring the information into the time domain for transmission; means for operating on the multiplexed information to introduce an arbitrary phase into the multiplexed information; a low pass filter on the output from the processor; and a local oscillator for upconverting the multiplexed information for transmission.
Claim 15
Dependent Claim
110 words
The transmitter of claim 14 further in combination with a receiver for receiving electromagnetic signals, the receiver comprising: a bandpass filter for filtering the received electromagnetic signals; a local oscillator for downconverting the received electromagnetic signals to produce output; a sampler for sampling the output of the local oscillator to produce sampled signals to the channel estimator; a channel estimator for estimating one or both of the amplitude and the phase differential of the received signals to produce as output one or both of an estimated amplitude and an estimated phase differential respectively; and a decoder for producing signals from the sampled signals and the output from the channel estimator.
Claim 16
Dependent Claim
28 words
The transmitter and receiver combination of claim 15 further including, in the receiver: a deprocessor for applying an inverse Fourier transform to the samples output from the sampler.
Claim 17
Dependent Claim
35 words
The transmitter and receiver combination of claim 16, further including, in the receiver: a power controller before the sampler for monitoring the power of the received signal and for controlling the power of the signal.
Claim 18
Dependent Claim
43 words
The transmitter and receiver combination of claim 15, further comprising: a pre-distorter before the processor, the pre-distorter being connected to the channel estimator, for predistorting a signal to be transmitted with one or both of the estimated amplitude or the estimated phase differential.
Claim 19
Dependent Claim
29 words
The transcmitter and receiver combination of claim 18 in which the power controller is also connected to the pre-distorter for controlling the power of the signal to be transmitted.
Claim 20
Dependent Claim
28 words
The transmitter and receiver combination of claim 15 further including: means to modify the received signal with one or both of the estimated amplitude and phase differential respectively.
Claim 21
Independent Claim
98 words
A method for allowing a number of wireless transceivers to exchange frames of information symbols, the method comprising the steps of: multiplexing a first frame of information symbols over a number of frequencies within a frequency band at a first transceiver to produce multiplexed information; processing the multiplexed information at the first transceiver, including introducing an arbitrary phase into the information symbols; 46 transmitting the processed information to second transceiver using a carrier frequency f c; receiving the processed information at the second transceiver; and prosing the processed information at the second transceiver during a first time interval.
Claim 22
Dependent Claim
28 words
The method of claim 21 in which the width of the frequency band being chosen so that neither carrier nor clock recovery is required at the second transceiver.
Claim 23
Dependent Claim
80 words
23 The method of claim 22 in which the frequency band is formed from a first set of K1 point and a pair of tail slots each having K2 points, each of the points being separated by a frequency range .DELTA.f, the second transceiver has a maximum expected clock error XT, where T is the duration of one time domain sample, the information is multiplexed over a number M of levels, and K1 is selected such that 2.pi.X/K1 < .pi./M.
Claim 24
Dependent Claim
26 words
The method of claim 23 further including transmitting a second frame of information from the second transceiver to the first transceiver within the same frequency band
Claim 25
Dependent Claim
23 words
The method of claim 23 in which K2 is selected o that the out of band signal is less than a given level.
Claim 26
Dependent Claim
67 words
The method of claim 23 in which the first and second transceiver have an expected maximum relative velocity V, the first and second transceivers have carrier frequencies with a frequency offset from 47 each other of f o, the carrier frequency has a corresponding travelling wavelength .lambda. and .DELTA.f is selected so that [V/(.lambda..DELTA.f) + f o/.DELTA.f] is less than or equal to a preselected sampling error.
Claim 27
Dependent Claim
38 words
The method of claim 23 in which processing the mutliplexed information at the second transceiver further includes calculating the mean of the phase shift due to sampling error by summing the estimated phase differential of the received signal.
Claim 28
Dependent Claim
33 words
The method of claim 27 in which the mean of the phase shift due to sampling error is divided by K1 and the result removed from the phase differential of the received signal.
Claim 29
Dependent Claim
79 words
A transmitter for transmitting electromagnetic signals having amplitide and phase differential characteristics, the transmitter comprising: an encoder for encoding information; a wideband frequency division multiplexer for multiplexing the encoded information onto wideband frequency channels; a processor having an output for applying a Fourier transform to the multiplexed information to bring the information into the time domain for transmission; a low pass filter on the output from the processor; and a local oscillator for upconverting the multiplexed information for transmission.
References Cited (Backward Citations)
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