Feed-forward self-interference cancellation

Patent metadata

Field	Value
Publication number	US-2017019136-A1
Application number	US-201514982444-A
Country	US
Kind code	A1
Filing date	Dec 29, 2015
Priority date	Jul 16, 2015
Publication date	Jan 19, 2017
Grant date	—

Abstract

The present application describes a feed forward method that may electronically cancel self-interference while it is still in the transmit path. It may employ delay length matching for electronic cancellation over large bandwidths.

First claim

What is claimed is:

1 . A feed-forward self-interference cancellation method, the method comprising:
receiving a transmit signal; sampling the transmit signal; amplifying the transmit signal; combining the sampled transmit signal with a sample of the amplified transmit signal; responsive to the combining, removing the transmit of the transmit signal and creating a self-interference sampled signal; and injecting the self-interference sampled signal with the amplified transmit signal to remove self-interference from the amplified transmit signal.

2 . The method of claim 1 , wherein the self-interference sample signal is approximately 180 degrees out of phase of the amplified transmit signal.

3 . The method of claim 1 , wherein the self-interference sample signal is approximately 180 degrees out of phase of the amplified transmit signal based on the use of at least one or more devices that manipulate amplitude or phase.

4 . The method of claim 3 , wherein the at least one or more devices that manipulate amplitude or phase is controlled by a controller, the controller incrementally manipulating at least one or more devices that manipulate amplitude or phase to find an optimal operating point for cancellation of self-interference.

5 . The method of claim 1 , wherien the self-interference sample signal has a first magnitude that is approximately equivalent to a second mangitude of the amplified transmit signal.

6 . The method of claim 1 , wherein the self-interference sample signal is amplified to a first magnitude, the first magnitude approximately equivalent to a second magnitude of the amplified transmit signal.

7 . A feed-forward self-interference cancellation system, the system comprising:
a main path comprising a power amplifier, the power amplifier amplifying a first transmit signal; a first path for carrier cancellation, the first path comprising:
a first sampler for sampling the first transmit signal, the first transmit signal sampled from the input side of the power amplifier along the main path; and
a first device for phase shifting or amplitude adjustment the first transmit signal; and
a second path for error cancellation, the second path comprising:
a second sampler for sampling the amplified first transmit signal on the output side of the power amplifier along the main path;
a first signal injector for creating a self-interference sampled signal, the self-interference sampled signal created based on injecting the phase shifted or amplitude adjusted first signal with the sampled amplified first transmit signal; and
a second signal injector for creating a self-interference canceled signal, the self-interference canceled signal created based on injecting the self-interference sampled signal into the main path with the amplified first transmit signal.

8 . The feed-forward self-interference cancellation system of claim 7 , wherein the first sampler is a coupler.

9 . The feed-forward self-interference cancellation system of claim 7 , wherein the first signal injector is a coupler.

10 . The feed-forward self-interference cancellation system of claim 7 , wherein the first device is at least one or more devices that manipulate amplitude or phase.

11 . The feed-forward self-interference cancellation system of claim 7 , further comprising a controller communicatively connected with the first device, the controller incrementally manipulating the first device to find an optimal operating point for the feed-forward self-interference cancellation system.

12 . A method of signal processing, the method comprising:
receiving a first transmit signal; amplifying the power of the first transmit signal which results in a second transmit signal; sampling the first transmit signal which results in a first sampled transmit signal; sampling the second transmit signal which results in a second sampled transmit signal; phase shifting or amplitude adjusting the first sampled transmit signal which results in a phase shifted or amplitude adjusted first sample signal; injecting the phase shifted or amplitude adjusted first sample signal with the second sampled transmit signal which results in a first interference signal; passing the first interference signal through a modulator and an amplifier which results in a second interference signal; and injecting the second interference signal with the second transmit signal which results in a third transmit signal.

13 . The method of claim 12 , wherein the first transmit signal is filtered by a bandpass filter before the amplifying of the power of the first transmist signal.

14 . The method of claim 13 , wherein the bandpass filter is a tunable filter.

15 . The method of claim 13 , wherein the bandpass filter is a switched bank of bandpass filters.

16 . The method of claim 12 , wherein the sampling of the first transmit signal is performed by a coupler.

17 . The method of claim 12 , wherein the phase shifting or amplitude adjusting of the first sampled transmit signal is performed by at least one or more devices that manipulate amplitude or phase.

18 . The method of claim 12 , wherein the phase shifted or amplitude adjusted sample signal is amplified to match the magnitude of the second sampled transmit signal.

19 . The method of claim 12 , wherein the phase shifted or amplitude adjusted sample signal is shifted 180 degrees in relation to the second sampled transmit signal.

20 . The method of claim 12 , wherein the phase shifted or amplitude adjusted sample signal is filtered by a bandpass filter before being injected with the second sampled transmit signal.

21 . The method of claim 20 , wherein bandpass filter is controlled by a controller, the controller incrementally manipulating the bandpass filter to find an optimal operating point.

22 . The method of claim 20 , wherein the bandpass filter is a tunable filter.

23 . The method of claim 20 , wherein the bandpass filter is a switched bank of bandpass filters.

Assignees

• LGS Innovations LLC

Inventors

• Brannon Alan Scott
• Pack Riley Nelson
• Baker Benjamin Joseph

Classifications

• H04B2001/0408

  with power amplifiers · CPC title

• H04B1/10

  Means associated with receiver for limiting or suppressing noise or interference · CPC title

• H04L5/1461 Primary

  Suppression of signals in the return path, i.e. bidirectional control circuits · CPC title

• H03F3/24 Primary

  of transmitter output stages · CPC title

• H04B1/713

  using frequency hopping · CPC title