Phase Noise Suppression

• US 20150188584A1
• Filed: 12/30/2014
• Published: 07/02/2015
• Est. Priority Date: 12/30/2013
• Status: Active Grant

• Current Assignee: Maxlinear Incorporated
• Original Assignee: Maxlinear Incorporated
• Inventors: Laurent-Michel, Stephane, Ling, Curtis
• Granted Patent: US 9,362,965 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04L 1/24 Testing correct operation
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 27/122 using digital generation of carrier signals digital function generators G06F1/02, H04L17/10; generating pulses having stepped portions using digital techniques H03K4/026
• CPC Class Codes: H04L 5/00 Arrangements affording multiple use of the transmission path
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

A transmitter comprises a local oscillator circuit operable to generate a reference signal, a modulator circuit operable to generate a data-carrying signal using the reference signal, and a test signal generator circuit operable to generate a test signal using the reference signal. The test signal has a first bandwidth, and a test signal insertion circuit is operable to combine the data-carrying signal and the test signal to generate a combined signal. An amount of bandwidth in the combined signal allocated to the test signal is greater than the first bandwidth such that a component of the combined signal corresponding to the test signal is bordered by whitespace. A receiver may then use the test signal to determine and correct for phase noise introduced in the transmitter.

Claims

1. A system comprising:

a local oscillator circuit operable to generate a reference signal;

a modulator circuit operable to generate a data-carrying signal using said reference signal;

a test signal generator circuit operable to generate a test signal using said reference signal, wherein said test signal has a first bandwidth;

a test signal insertion circuit operable to combine said data-carrying signal and said test signal to generate a combined signal, wherein an amount of bandwidth in said combined signal allocated to said test signal is greater than said first bandwidth such that a component of said combined signal corresponding to said test signal is bordered by whitespace.

2. The system of claim 1, wherein said bandwidth in said combined signal allocated to said test signal is at least one order of magnitude larger than said first bandwidth.

3. The system of claim 1, comprising a digital-to-analog converter operable to convert said combined signal to a corresponding analog signal.

4. The system of claim 3, comprising an analog front-end operable to upconvert said combined signal to a microwave frequency signal and transmit said microwave frequency signal.

5. The system of claim 4, comprising:

a receive analog front-end circuit operable to receive said microwave frequency signal and convert said microwave frequency signal to an analog baseband signal;

an analog-to-digital converter operable to convert said baseband signal to a digital baseband signal;

a test signal processing circuit operable to select a portion of said digital baseband signal corresponding to said test signal and process said portion of said digital baseband signal to generate a signal indicative of phase of said test signal; and

a phase noise removal circuit operable to correct phase noise in a data portion of said digital baseband signal based on said signal indicative of phase of said test signal.

6. The system of claim 4, wherein:

a bandwidth of said microwave frequency signal is at least one order of magnitude larger than said bandwidth in said combined signal allocated to said test signal; and

said bandwidth in said combined signal allocated to said test signal is at least one order of magnitude larger than said first bandwidth.

7. The system of claim 1, wherein said local oscillator circuit, said modulator circuit, test signal generator circuit, and said test signal insertion circuit are integrated in a microwave backhaul assembly.

8. The system of claim 1, wherein said amount of bandwidth in said combined signal allocated to said test signal varies in response to variation of a performance metric measured for said combined signal.

9. The system of claim 8, wherein said performance metric comprises one of:

signal-to-noise ratio, symbol error rate, and bit error rate.

10. The system of claim 8, wherein said performance metric is an indication of phase noise.

13. The system of claim 1, wherein a bandwidth of said microwave frequency signal is at least one order of magnitude larger than said bandwidth of said whitespace.

14. The system of claim 13, wherein said circuitry operable to receive said microwave frequency signal comprises an analog front-end circuit operable to downconvert said microwave frequency signal to a baseband signal.

15. The system of claim 13, wherein said circuitry operable to receive said microwave frequency signal comprises an analog-to-digital converter operable to convert said baseband signal to a digital baseband signal.

17. The system of claim 1, wherein said wherein said circuitry operable to receive said microwave frequency signal, said test signal processing circuit, and said phase noise removal circuit are integrated in a microwave backhaul assembly.

11. A system comprising:

circuitry operable to receive a microwave frequency signal comprising a test signal portion and a data portion, wherein said test signal portion comprises a test signal component and whitespace bordering said test signal component;

a test signal processing circuit operable to select said test signal portion and process said test signal portion to generate a signal indicative of phase of said test signal component; and

a phase noise removal circuit operable to correct phase noise in said data portion based on said signal indicative of phase of said test signal component.

12. The system of claim 11, wherein a bandwidth of said whitespace is at least one order of magnitude larger than a bandwidth of said test signal component.

16. The system of claim 11, comprising:

a local oscillator circuit operable to generate a reference signal;

a modulator circuit operable to generate a data-carrying signal using said reference signal;

a test signal generator circuit operable to generate a test signal using said reference signal, wherein a bandwidth of said test signal is said bandwidth of said test signal component;

a test signal insertion circuit operable to combine said data-carrying signal and said test signal to generate a combined signal;

an analog front-end operable to upconvert said combined signal to generate said microwave frequency signal.

18. The system of claim 11, comprising circuitry for measuring a performance metric for said microwave frequency signal.

19. The system of claim 18, wherein said performance metric comprises one of:

signal-to-noise ratio, symbol error rate, and bit error rate.

20. The system of claim 18, wherein said performance metric is an indication of phase noise.