Analog self-interference cancellation systems for CMTS

• US 10,382,085 B2
• Filed: 12/21/2018
• Issued: 08/13/2019
• Est. Priority Date: 08/01/2017
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Kumu Networks, Inc.
• Inventors: Choi, Jung-Il, Hahn, Wilhelm Steffen, Jain, Mayank
• Primary Examiner(s): Malek, Leila
• Application Number:
  US16/230,077
• Publication Number:
  US 20190149186A1
• Time in Patent Office: 235 Days
• Field of Search: 375285
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 1/44 Transmit/receive switching
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04L 25/0328 with interference cancellation circuitry adaptations for interference cancellation within a sequence estimator H04L25/03305; interference related aspects of direct sequence spread spectrum H04B1/7097; interference related aspects of frequency hopping spread spectrum H04B1/715; see also H04B1/10
• CPC Class Codes: H04L 27/2691 involving interference determination or cancellation
• CPC Class Codes: H04L 27/38 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/1423 for simultaneous baseband signals
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

A system for wired analog self-interference cancellation includes a coarse delayer that delays a sampled RF transmit signal by a first delay amount; a frequency downconverter that downconverts the sampled RF transmit signal to IF; a first canceller tap group comprising a first per-tap-group delayer, a first sampling coupler, a first per-tap delayer, and first and second analog vector modulators that generates an IF self-interference cancellation signal; a frequency upconverter that upconverts the IF self-interference cancellation signal to RF; and a receive coupler that combines the RF self-interference cancellation signal with the RF receive signal, reducing self-interference.

Claims

1. A system for wired analog self-interference cancellation comprising:

a transmit coupler, communicatively coupled to a radio frequency (RF) transmit signal of a wired communication system, that samples the RF transmit signal to create a sampled RF transmit signal having an RF carrier frequency;

an analog-self-interference canceller comprising;

a frequency downconverter, comprising a mixer, a local oscillator, and an intermediate frequency (IF) filter, wherein the frequency downconverter converts, by heterodyning, the sampled RF transmit signal to a sampled IF transmit signal having an IF carrier frequency, wherein the IF carrier frequency is less than the RF carrier frequency;

a first coarse delayer that delays the sampled IF transmit signal by a first delay amount, resulting in a delayed sampled IF transmit signal;

wherein the first coarse delayer delays the sampled IF transmit signal after frequency downconversion; and

a first canceller tap group comprising a first per-tap-group delayer, a first sampling coupler, a first per-tap delayer, first and second analog vector modulators, and a first combining coupler;

wherein the first per-tap-group delayer further delays the delayed sampled IF transmit signal;

wherein the first sampling coupler splits the delayed sampled IF transmit signal, after the first per-tap-group delayer, into first and second IF transmit signal components;

wherein the first analog vector modulator generates a first IF self-interference cancellation signal component from the first IF transmit signal component;

wherein the first per-tap delayer delays the second IF transmit signal component, resulting in a delayed second IF transmit signal component;

wherein the second analog vector modulator generates a second IF self-interference cancellation signal component from the delayed second IF transmit signal component;

wherein the first combining coupler combines the first and second IF self-interference cancellation signal components to generate an IF self-interference cancellation signal;

a frequency upconverter comprising a mixer, a local oscillator, and an RF filter, wherein the frequency upconverter converts, by heterodyning, the IF self-interference cancellation signal to an RF self-interference cancellation signal having the RF carrier frequency; and

a receive coupler, communicatively coupled to an RF receive signal of the wired communication system, that combines the RF self-interference cancellation signal with the RF receive signal, resulting in an RF composite receive signal;

wherein the RF composite receive signal contains less self-interference than the RF receive signal.

2. The system of claim 1, wherein the first coarse delayer comprises a discretely variable surface-acoustic-wave (SAW) delayer having a range of at least 1.5 microseconds.

3. The system of claim 2, wherein the first coarse delayer has delay steps of at least 150 nanoseconds.

4. The system of claim 2, wherein the first coarse delayer comprises a chain of amplified delays in series, each amplified delay of the chain coupled to a coarse delayer coupling point;

wherein delays of the first coarse delayer are varied based on selection of first delayer coupling points.

5. The system of claim 4, wherein the first per-tap-group delayer comprises a chain of bypassable delay blocks;

wherein each of the bypassable delay blocks comprises an inductor-capacitor (LC) delay and an amplifier;

wherein the bypassable delay blocks are binary encoded.

6. The system of claim 5, wherein the first per-tap-group delayer has a base step of between one and ten nanoseconds.

7. The system of claim 5, wherein the first per-tap delayer has a fixed delay.

8. The system of claim 5, further comprising an analog self-interference canceller controller that adapts configuration parameters of the analog self-interference canceller based on at least one of transmit signal data, receive signal data, and environmental data;

wherein the configuration parameters include tunable parameters of the first and second analog vector modulators and bypass settings of the first per-tap-group delayer.

9. The system of claim 8, wherein the selection of first delayer coupling points is set based on measured drop distances between cable modem couplers coupled to the system.

10. The system of claim 8, wherein the selection of first delayer coupling points is set automatically by the analog self-interference canceller controller based upon analysis of primary reflections observed at the system.

11. A system for wired analog self-interference cancellation comprising:

a transmit coupler, communicatively coupled to a radio frequency (RF) transmit signal of a wired communication system, that samples the RF transmit signal to create a sampled RF transmit signal having an RF carrier frequency;

an analog-self-interference canceller comprising;

a frequency downconverter, comprising a mixer, a local oscillator, and an intermediate frequency (IF) filter, wherein the frequency downconverter converts, by heterodyning, the sampled RF transmit signal to a sampled IF transmit signal having an IF carrier frequency, wherein the IF carrier frequency is less than the RF carrier frequency;

a first coarse delayer that generates a first delayed sampled IF transmit signal by delaying the sampled IF transmit signal by a first delay amount and generates a second delayed sampled IF transmit signal by delaying the sampled IF transmit signal by a second delay amount;

wherein the second delay amount is greater than the first delay amount;

wherein the first coarse delayer generates delayed sampled IF transmit signals after frequency downconversion;

a first canceller tap group comprising a first per-tap-group delayer, a first sampling coupler, a first per-tap delayer, and first and second analog vector modulators;

wherein the first per-tap-group delayer further delays the first delayed sampled IF transmit signal;

wherein the first sampling coupler splits the first delayed sampled IF transmit signal, after the first per-tap-group delayer, into first and second IF transmit signal components;

wherein the first analog vector modulator generates a first IF self-interference cancellation signal component from the first IF transmit signal component;

wherein the first per-tap delayer delays the second IF transmit signal component, resulting in a delayed second IF transmit signal component;

wherein the second analog vector modulator generates a second IF self-interference cancellation signal component from the delayed second IF transmit signal component;

a second canceller tap group comprising a second per-tap-group delayer, a second sampling coupler, a second per-tap delayer, and third and fourth analog vector modulators;

wherein the second per-tap-group delayer further delays the second delayed sampled IF transmit signal;

wherein the second sampling coupler splits the second delayed sampled IF transmit signal, after the second per-tap-group delayer, into third and fourth IF transmit signal components;

wherein the third analog vector modulator generates a third IF self-interference cancellation signal component from the third IF transmit signal component;

wherein the second per-tap delayer delays the fourth IF transmit signal component, resulting in a delayed fourth IF transmit signal component;

wherein the fourth analog vector modulator generates a fourth IF self-interference cancellation signal component from the delayed fourth IF transmit signal component; and

a combining coupler that combines the first, second, third, and fourth IF self-interference cancellation signal components to generate an IF self-interference cancellation signal;

a frequency upconverter comprising a mixer, a local oscillator, and an RF filter, wherein the frequency upconverter converts, by heterodyning, the IF self-interference cancellation signal to an RF self-interference cancellation signal having the RF carrier frequency; and

a receive coupler, communicatively coupled to an RF receive signal of the wired communication system, that combines the RF self-interference cancellation signal with the RF receive signal, resulting in an RF composite receive signal;

wherein the RF composite receive signal contains less self-interference than the RF receive signal.

12. The system of claim 11, wherein the combining coupler combines the first and second IF self-interference cancellation signal components to form a first IF self-interference cancellation signal super-component;

wherein the combining coupler combines the third and fourth IF self-interference cancellation signal components to form a second IF self-interference cancellation signal super-component;

wherein the combining coupler generates the IF self-interference cancellation signal by combining the first and second IF self-interference cancellation signal super-components.

13. The system of claim 11, wherein the first coarse delayer comprises a chain of delays in series, each delay of the chain coupled to coarse delayer coupling points;

wherein delays of the first coarse delayer are varied based on selection of the delayer coupling points.

14. The system of claim 13, wherein the first coarse delayer takes the sampled IF transmit signal as input at a first coarse delayer coupling point, outputs the first delayed sampled IF transmit signal at a second delayer coupling point, and outputs the second delayed sampled IF transmit signal at a third delayer coupling point;

wherein the third delayer coupling point is farther along the chain of delays than the second delayer coupling point.

15. The system of claim 14, wherein the second and third delayer coupling points are amplified by amplifiers of the first coarse delayer.

16. A system for wired analog self-interference cancellation comprising:

a transmit coupler, communicatively coupled to a radio frequency (RF) transmit signal of a wired communication system, that samples the RF transmit signal to create a sampled RF transmit signal having an RF carrier frequency;

an analog-self-interference canceller comprising;

a frequency downconverter, comprising a mixer, a local oscillator, and an intermediate frequency (IF) filter, wherein the frequency downconverter converts, by heterodyning, the sampled RF transmit signal to a sampled IF transmit signal having an IF carrier frequency, wherein the IF carrier frequency is less than the RF carrier frequency;

a sampling coupler that splits the sampled IF transmit signal into first and second sampled IF transmit signals;

a first canceller tap group comprising a first per-tap-group delayer, a first sampling coupler, a first per-tap delayer, first and second analog vector modulators, and a first coupling combiner;

wherein the first per-tap-group delayer delays the first sampled IF transmit signal;

wherein the first sampling coupler splits the first sampled IF transmit signal, after the first per-tap-group delayer, into first and second IF transmit signal components;

wherein the first analog vector modulator generates a first IF self-interference cancellation signal component from the first IF transmit signal component;

wherein the first per-tap delayer delays the second IF transmit signal component, resulting in a delayed second IF transmit signal component;

wherein the second analog vector modulator generates a second IF self-interference cancellation signal component from the delayed second IF transmit signal component;

wherein the first combining coupler combines the first and second IF self-interference cancellation signal components to generate a first IF self-interference cancellation signal super-component;

a second canceller tap group comprising a second per-tap-group delayer, a second sampling coupler, a second per-tap delayer, third and fourth analog vector modulators, and a second combining coupler;

wherein the second per-tap-group delayer delays the second sampled IF transmit signal;

wherein the second sampling coupler splits the second sampled IF transmit signal, after the second per-tap-group delayer, into third and fourth IF transmit signal components;

wherein the third analog vector modulator generates a third IF self-interference cancellation signal component from the third IF transmit signal component;

wherein the second per-tap delayer delays the fourth IF transmit signal component, resulting in a delayed fourth IF transmit signal component;

wherein the fourth analog vector modulator generates a fourth IF self-interference cancellation signal component from the delayed fourth IF transmit signal component;

wherein the second combining coupler combines the third and fourth IF self-interference cancellation signal components to generate a second IF self-interference cancellation signal super-component;

a first coarse delayer that delays the first IF self-interference cancellation signal super-component by a first delay amount, delays the second IF self-interference cancellation signal super-component by a second delay amount, and combines the first and second IF self-interference cancellation signal super-components to generate an IF self-interference cancellation signal;

wherein the second delay amount is greater than the first delay amount;

a frequency upconverter comprising a mixer, a local oscillator, and an RF filter, wherein the frequency upconverter converts, by heterodyning, the IF self-interference cancellation signal to an RF self-interference cancellation signal having the RF carrier frequency; and

a receive coupler, communicatively coupled to an RF receive signal of the wired communication system, that combines the RF self-interference cancellation signal with the RF receive signal, resulting in an RF composite receive signal;

wherein the RF composite receive signal contains less self-interference than the RF receive signal.

17. The system of claim 16, wherein the first coarse delayer comprises a chain of delays in series, each delay of the chain coupled to coarse delayer coupling points;

wherein delays of the first coarse delayer are varied based on selection of the coarse delayer coupling points.

18. The system of claim 17, wherein the first coarse delayer takes the first IF self-interference cancellation signal super-component as input at a first coarse delayer coupling point, takes the second IF self-interference cancellation signal super-component as input at a second coarse delayer coupling point, and outputs the IF self-interference cancellation signal at a third delayer coupling point;

wherein the first delayer coupling point is between the second and third coupling points along the chain of delays.

19. The system of claim 18, wherein the selection of the coarse delayer coupling points is set based on measured drop distances between cable modem couplers coupled to the system.

20. The system of claim 18, wherein the selection of coarse delayer coupling points is set automatically by an analog self-interference canceller controller based upon analysis of primary reflections observed at the system.