Patent EP0562868A2 successfully refreshed from Google Patents.
EP0562868A2
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EP
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Method and apparatus for multiple access between transceivers in wireless communication using OFDM spread spectrum
Assignee: Quarterhill Inc
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Filing: 1993-03-25
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Granted: —
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Expires: 2013-03-25
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. Use/advantage: Time and frequency multiplexing, Multiple access in wideband transmission
Inventors
- 👤 Michael Fattouche
- 👤 Hatim Zagloul
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 16:58
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/26; H04L27/2601; H04L27/2602; H04B; H04B1/00; H04B1/69; H04B1/707; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03343; H04L27/2626; H04L27/2627; H04L27/2647; H04L27/2649; H04L5/00; H04L5/02; H04L5/023; H04L5/026; H04L2025/0335; H04L2025/03375; H04L2025/03414
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
73 words
A transceiver including a transmitter for transmitting electromagnetic signals and a receiver for receiving electromagnetic signals, the transmitter comprising: an encoder for encoding information; a wideband frequency division multiplexer for multiplexing the information onto wideband frequency channels; a low pass filter; a local oscillator for upconverting the multiplexed information for transmission; and a processor for applying a Fourier transform to the multiplexed information to bring the information into the time domain for transmission.
Claim 2
Dependent Claim
60 words
The transceiver of claim 1 in which the received signals have amplitude and phase characteristics and further including, in the receiver of the transceiver: 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.
Claim 3
Dependent Claim
71 words
The transceiver of claim 1 or 2 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; and a decoder for producing signals from the sampled signals and the output from the channel estimator.
Claim 4
Dependent Claim
28 words
The transceiver of claim 3 further including, in the receiver of the transceiver: a deprocessor for applying an inverse Fourier transform to the samples output from the sampler.
Claim 5
Dependent Claim
37 words
The transceiver of claims 3 or 4, 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 6
Dependent Claim
51 words
The transceiver of any one of claims 2 - 5, 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 7
Dependent Claim
26 words
The transceiver of claim 6 in which the power controller is also connected to the pre-distorter for controlling the power of the signal to be transmitted.
Claim 8
Dependent Claim
30 words
The transceiver of any one of claims 2 - 7 further including: means to modify the received signal with one or both of the estimated amplitude and phase differential respectively.
Claim 9
Independent Claim
115 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 to produce processed information; transmitting the processed information to a second transceiver using a carrier frequency f c ; receiving the processed information at the second transceiver; and processing the processed information at the second transceiver during a first time interval; in which the width of the frequency band is chosen so that neither carrier nor clock recovery is required at the second transceiver.
Claim 10
Dependent Claim
101 words
The method of claim 9 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 Δf, the second transceiver has a maximum expected clock error χT, 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 2πχ/K₁ ≦ π/M, whereby the width of the frequency band is chosen so that neither carrier nor clock recovery is required at the second transceiver.
Claim 11
Independent Claim
28 words
The method of claims 9 or 10 further including transmitting a second frame of information from the second transceiver to the first transceiver within the same frequency band.
Claim 12
Dependent Claim
23 words
The method of claim 11 in which K₂ is selected so that the out of band signal is less than a given level.
Claim 13
Independent Claim
70 words
The method of claims 11 or 12 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 λ and Δf is selected so that [V/(λΔf) + f o /Δf] is less than or equal to a preselected sampling error.
Claim 14
Independent Claim
43 words
The method of any one of claims 9 - 13 in which processing the multiplexed 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 15
Dependent Claim
33 words
The method of claim 14 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 16
Independent Claim
63 words
The method of any of claims 11 - 15 further comprising: transmitting the second frame of information from the first transceiver to the second transceiver after a preselected time interval after transmitting the first frame of information from the first transceiver to the second transceiver; and during the preselected time interval, exchanging information between the second transceiver and at least one other transceiver.
References Cited (Backward Citations)
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