Simultaneous two-way transmission of information signals in the same frequency band

• US 7,187,907 B2
• Filed: 05/09/2001
• Issued: 03/06/2007
• Est. Priority Date: 05/09/2000
• Status: Expired due to Fees

• Current Assignee: Bernard Widrow
• Original Assignee: Bernard Widrow
• Inventors: Widrow, Bernard
• Primary Examiner(s): Vuong; Quochien B.
• Assistant Examiner(s): Rego; Dominic E.
• Application Number:
  US09/852,469
• Publication Number:
  US 20020032004A1
• Time in Patent Office: 2,127 Days
• Field of Search: 455/3.05, 455/7, 455/15, 455/13.1, 455/16, 455/279.1, 455/559, 455/523, 455/114.3, 455/144, 455/197.1, 455/242.1, 455/282, 455/73, 379/1.03, 379/1.04, 379/4, 379/93.01, 379/338, 379/12, 375/318, 375/222, 375/211, 375/220, 375/225, 375/240.15, 375/244, 375/297, 359/636, 359/722
• US Class Current: 455/73
• CPC Class Codes: H04B 3/36 Repeater circuits H04B3/58 takes precedence
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex

Abstract

This invention provides designs for communication systems that use adaptive filters in circuits whose purpose is to enable two-way transmission of information signals in the same frequency band at the same time over twisted pair channels, coaxial cable channels, fiber optic channels, or wireless channels. The methodology allows two-way DSL transmission over telephone lines, making use of existing DSL hardware and signal standards, so that the upload speed is increased by an approximate factor of ten. Applied to wireless systems with single antennas at the two ends of the channel, a doubling of the data rate is achieved for a given bandwidth. Applied to wireless systems with 2-way adaptive antenna arrays at a central location and a 2-way adaptive antenna array at each of a plurality of subscriber locations, the data rate for a given bandwidth is increased by a large factor.

Claims

1. A 2-way terminus device, based on adaptive filtering, for connecting both a signal source and a signal receiver to an end of a cable or wire channel for simultaneous transmission and reception of data signals in the same frequency band in said cable or wire channel, comprising:

(a) a signal source and a first isolation amplifier, and an adaptive filter whose input is connected to said signal source through said first isolation amplifier,

(b) a difference amplifier, and a connection between the output of said adaptive filter and the negative input of said difference amplifier,

(c) a connection between said cable or wire channel and the positive input of said difference amplifier, connected to an output terminal to provide a connection to said signal receiver, the output of said difference amplifier, being the received signal,

(d) a connection between the output of said difference amplifier and the error signal input of said adaptive filter,

(e) a connection between the output of said first isolation amplifier and a small signal delay unit Δ

whose output provides an input to a second isolation amplifier, said second isolation amplifier having the capability for signal amplification while driving a low impedance load, said delay unit having delay ranging from zero to the time duration of the impulse response of said adaptive filter,

(f) a connection between the output of said second isolation amplifier and a first terminal of an impedance whose impedance value is equal to the characteristic impedance of said cable or wire channel,

(g) a connection between the second terminal of said impedance and the said cable or wire channel, thus providing a two-way signal connection between said 2-way terminus device and said cable or wire channel, and

(h) an adaptive algorithm stored in and implemented by said adaptive filter for the purpose of minimization of the mean square of said error.

2. The 2-way terminus device of claim 1, wherein said input signal is digital, said output signal is digital, and the said output of said second isolation amplifier is digital, and said adaptive filter is implemented in digital form, having a digital input signal, a digital error signal, a digital output signal, and having a sampling frequency or cycle frequency synchronized to that of the said input signal, the said output signal, and the said output of said second isolation amplifier.

3. The 2-way terminus device of claim 1, wherein said adaptive filter has:

(a) an analog-to-digital converter to convert the analog input signal to a digital input signal,

(b) an analog-to-digital converter to convert the analog error signal to a digital error signal,

(c) a digital adaptive filter connected and configured so that its input signal is the said digital input signal, its error signal is the said digital error signal, and its output is a digital output signal, and

(d) a digital-to-analog converter to convert said digital output signal to analog form to provide an analog output signal for the said adaptive filter.

4. A two way-wireless communication system for simultaneous transmission and reception of information signals in the same frequency band or in overlapping frequency bands comprising:

(a) a radio transmitter, a radio receiver, and an antenna,

(b) a coupling means such as a transformer, a directional coupler, or some other electric network for connecting said transmitter and said receiver to said antenna,

(c) an RF modulator and a source of baseband signal to be transmitted, said baseband signal provided as the input to said RE modulator,

(d) an RF power amplifier and a delay device for connecting the output of said RE modulator to said RF power amplifier serving as the transmitter, the delay time of said delay device being small, ranging from zero to the impulse response duration of said RF amplifier,

(e) a connection between the output of said RF amplifier and said coupling means to couple the transmitter to said antenna,

(f) a subtractive means, and a connection between said coupling means and the positive input of said subtractive means,

(g) an adaptive filter,

(h) a connection between the output of said RF modulator and the input of said adaptive filter,

(i) a radio receiver, and a connection between the output of said adaptive filter and the negative input of said subtractive means, the output of said subtractive means connected to the input of said radio receiver,

(j) a connection between the output of said subtractive means and the error input of said adaptive filter to provide an error signal for adapting said adaptive filter,

(k) an adaptive algorithm or mathematical procedure implemented by said adaptive filter for adjusting its parameters for minimization of the mean square of said error signal, and

(l) an output terminal of the radio receiver for outputting a received baseband signal.

5. A 2-way terminus device, incorporating a directional coupler and based on adaptive filtering, for connecting both a signal source and a signal receiver to an end of cable or wire channel for simultaneous transmission and reception of data signals in the same frequency band or in overlapping bands comprising:

(a) a first isolation amplifier, and an adaptive filter whose input is connected to said signal source through said first isolation amplifier,

(b) a difference amplifier, and a connection between the output of said adaptive filter and the negative input of said difference amplifier,

(c) a delay device, and a connection between the adaptive filter input and the input of a delay device, said delay device implementing a small signal delay whose duration could range from zero to the impulse response duration of said difference amplifier,

(d) a connection between the output of said delay device and the input of said second isolation amplifier,

(e) a first impedance device, and a connection between the output of said second isolation amplifier and the first terminal of said first impedance device whose impedance is equal to the characteristic impedance of said cable or wire channel, and a connection between the second terminal of said first impedance device and the input terminal of said directional coupler,

(f) a connection between the output terminal of said directional coupler and the positive input of said difference amplifier,

(g) a second impedance device, and a second impedance device, and a connection between the output terminal of said directional coupler and the first terminal of said second impedance device whose impedance is equal to the characteristic impedance of said cable or wire channel, and a connection between the second terminal of said second impedance device and ground,

(h) a connection between the 2-way terminal of said directional coupler and said cable or wire channel,

(i) a received output signal, and a connection between the output of said difference amplifier and a terminal for outputting said received output signal,

(j) a connection between the output of said difference amplifier and the error input terminal of said adaptive filter for providing an error signal for the adaptive filter, and

(k) an adaptive algorithm or mathematical procedure implemented by said adaptive filter for adjusting its parameters for minimization of the mean square of said error signal.

6. A signal or information transmission system providing wireless individual two-way communication paths between a central antenna array and a plurality of subscriber antenna arrays, all or most communication signals being in the same frequency band, the central array and the distant subscriber arrays all connected respectively to 2-way adaptive beamformers in order to create nulls in their directivity patterns in the directions of all sources of interference, said antenna arrays not transmitting to or receiving from said directions, said information transmission system comprised of:

(a) a central antenna array, a plurality of 2-way adaptive beamformers, at least one individual 2-way adaptive beamformer for each distant subscriber, each of said adaptive beamformers transmitting and receiving through connections with the antenna elements of said central antenna array, each of said 2-way adaptive beamformers comprising,

(1) a plurality of adaptive beamformers, whose number is equal to the number of antenna elements of said central antenna array,

(2) coupling devices connecting to each of said elements to the inputs of each of said adaptive filters, a summing device whose inputs are connected to the output of said adaptive filters, a first subtractive device whose positive input is the summed signal of said summing device, a radio receiver whose input signal is the output signal of said subtractive device, the output of said radio receiver being the received baseband signal, a baseband signal to be transmitted which is inputted to an RF modulator, the output of said RF modulator providing inputs to a plurality of controlled filters that correspond one for one to the said adaptive filters, the architecture and weight values of the controlled filters set to correspond at each moment of time, to the corresponding weights of the adaptive filters, a subtracting adaptive filter whose input signal is the output signal of the said RF modulator, whose output signal is inputted to the negative input of said first subtractive device, the output of said first subtractive device provided as the error signal for said subtracting adaptive filter, so that it can subtract the transmitted signal from the radio receiver input, a coded pilot signal generator for generating a pilot signal used while the 2-way adaptive beamformer is trained, said pilot signal inputted to the positive input of a second subtractive device, the output of said summing device connected to the negative input of said second subtractive device, the output signal of said second subtractive device provided as an error signal during training for all of the adaptive filters of said plurality of adaptive filters, a plurality of RF amplifiers to provide RF power for wireless transmission, the input signals for said RF amplifier are the corresponding output signals from said controlled filters, and connections between the output signals from said RF amplifier and the corresponding said coupling devices provide RF driving currents for the elements of the central antenna array,

(3) subtracting adaptive filters configured for canceling all transmitted signals of the central antenna array from the inputs of all of the radio receivers, the number of transmitters and the number of receivers equal to the number of distant subscribers,

(b) a plurality of distant subscriber antenna arrays each connected and configured as part of a system for the two-way communication with the central antenna array, each said system comprised of,

(1) a subscriber'"'"'s array of antenna elements located away from the central antenna array,

(2) a 2-way adaptive beamformer connected to the antenna elements of said subscriber'"'"'s array,

(3) an output terminal of the 2-way beamformers for outputting the received baseband signal and an input terminal of the 2-way beamformer for inputting the baseband signal to be transmitted, and

(4) a pilot signal generator used during training of subscriber'"'"'s 2-way beamformers, said pilot signal being random, of finite length, and uncorrelated with all other pilot signals used in said information transmission system.

7. The signal or information transmission system of claim 6, wherein said central antenna array contains one or more antenna elements, and wherein each antenna array of said plurality of distant subscriber antenna arrays contains one or more antenna elements.