Burst detector

• US 6,993,100 B2
• Filed: 12/12/2000
• Issued: 01/31/2006
• Est. Priority Date: 12/12/2000
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Yang, Ganning, Walley, John
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Joseph, Jaison
• Application Number:
  US09/735,369
• Publication Number:
  US 20020168034A1
• Time in Patent Office: 1,876 Days
• Field of Search: 375/317, 375/341, 375/342, 455/522
• US Class Current: 375/342
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04L 2007/047 using a sine signal or unmodulated carrier
• CPC Class Codes: H04L 25/062 Setting decision thresholds using feedforward techniques only
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

A system for detecting a burst in a wireless communications system. A signal strength indicator indicates the strength of an incoming signal representative of incoming packets. A signal strength change detector detects changes in the signal strength of the incoming signal. Signal strength detection logic determines if a change in signal strength of a predetermined magnitude has occurred. A pattern detector detects patterns of symbols, or symbol estimates, in the incoming signal to determine if a predetermined pattern of symbols is present. Burst detection logic signals detection of a burst if the signal strength detection logic determines that a change in signal strength of predetermined magnitude has occurred, and the pattern detector determines that a predetermined pattern of symbols is present.

Claims

1. A burst detection system for detecting a burst in an incoming signal comprising:

a signal strength change detector for determining strength changes in the incoming signal;

signal strength detection logic for determining if a change in signal strength of a predetermined magnitude has occurred;

a pattern detector for monitoring patterns of symbols in the incoming signal to determine if a predetermined pattern is present;

a burst detector for signaling a detection of a burst if the signal strength change detection logic determines that a signal strength change of predetermined magnitude has occurred and the pattern detector determines that a predetermined pattern of symbols is present;

a signal strength indicator for indicating the strength of the incoming signal;

a short-term signal strength change detector for determining, responsive to the signal strength indicator, short-term changes in signal strength, and a long-term signal strength change indicator for determining, responsive to the signal strength indicator, longterm changes in signal strength;

wherein the signal strength detection logic is configured to determine, responsive to the short-term and long-term signal strength change detectors, if a short-term change in signal strength of a predetermined magnitude has occurred, and a long-term change in signal strength of a predetermined magnitude has occurred;

a signal strength indicator for indicating the strength of the incoming signal, and the short-term and long-term signal strength change detectors respectively determine short-term and long-term changes in signal strength responsive to the indication of signal strength provided by the signal strength indicator;

wherein the short-term signal strength change detector is configured to determine A_n, a current moving average of M samples of a_n, the indication of signal strength provided by the signal strength indicator, and B_n, a previous moving average of M samples of a_n, where M is a non-negative integer.

2. The system of claim 1 wherein the signal strength change detection logic is configured to determine if a short-term change in signal strength of sufficient magnitude has occurred by determining if the ratio of A_n to B_n exceeds a predetermined threshold.

3. The system of claim 1 wherein the short-term signal strength change detector is configured to determine C_n, a long-term average of a_n, in accordance with the following expression:

C_n=(1−

σ

)*C_n-1+a_n, where σ

is less than or equal to 1, and indicates the relative weights to be given to C_n-1 and a_n in the computation of C_n.

4. The system of claim 3 wherein the signal strength change detection logic is configured to determine if a change in signal strength of predetermined magnitude has occurred by determining if the ratio of A_n to C_n exceeds a predetermined magnitude.

5. A burst detection system for detecting a burst in an incoming signal comprising:

a signal strength change detector for determining strength changes in the incoming signal;

signal strength detection logic for determining if a change in signal strength of a predetermined magnitude has occurred;

a pattern detector for monitoring patterns of symbols in the incoming signal to determine if a predetermined pattern is present;

a burst detector for signaling a detection of a burst if the signal strength change detection logic determines that a signal strength change of predetermined magnitude has occurred and the pattern detector determines that a predetermined pattern of symbols is present;

a signal strength indicator for indicating the strength of the incoming signal;

a short-term signal strength change detector for determining, responsive to the signal strength indicator, short-term changes in signal strength, and a long-term signal strength change indicator for determining, responsive to the signal strength indicator, longterm changes in signal strength;

wherein the signal strength detection logic is configured to determine, responsive to the short-term and long-term signal strength change detectors, if a short-term change in signal strength of a predetermined magnitude has occurred, and a long-term change in signal strength of a predetermined magnitude has occurred;

a symbol detector for detecting symbols, or estimates thereof, in the incoming signal, and the pattern detector monitors the symbols or estimates provided by the symbol detector to determine if a predetermined pattern of symbols is present;

wherein the incoming signal is a quadrature baseband signal, and the symbol detector determines soft estimates δ

θ

_n of the symbols; and

a symbol spaced differentiator for determining, responsive to the samples δ

θ

_n from the symbol detector, δ

δ

θ

_{n =}δ

θ

_{n −}

δ

θ

_n-L where L is the number of samples/symbol.

6. The system of claim 5 wherein the pattern detector determines if a predetermined pattern of symbols is present responsive to the values δ

δ

θ

_n from the symbol spaced differentiator.

7. A method for detecting a burst in an incoming signal comprising:

monitoring short-term signal strength changes in the incoming signal to determine if a short-term change in signal strength of predetermined magnitude has occurred;

monitoring long-term signal strength changes in the incoming signal to determine if a long-term change in signal strength of predetermined magnitude has occurred;

monitoring patterns of symbols in the incoming signal to determine if a predetermined pattern is present;

performing the foregoing three monitoring steps in parallel;

signaling detection of a burst if a short-term signal strength change of predetermined magnitude has occurred, a long-term signal strength change of predetermined magnitude has occurred, and a predetermined pattern of symbols is present;

indicating the strength of the incoming signal, and monitoring short-term and long-term changes in signal strength responsive to the indication of signal strength; and

determining A_n, a current moving average of M samples of a_n, the indication of signal strength, and B_n, a previous moving average of M samples of a_n, where M is a non-negative integer.

8. The method of claim 7 further comprising determining if a short-term change in signal strength of sufficient magnitude has occurred by determining if the ratio of A_n to B_n exceeds a predetermined threshold.

9. The method of claim 7 further comprising determining C_n, a long-term average of a_n, in accordance with the following expression:

C_n=(1-σ

)·

C_n-1+σ

·

a_n, where a is less than or equal to 1, and indicates the relative weights to be given to C_n-1 and a_n in the computation of C_n.

10. The method of claim 9 further comprising determining if a change in signal strength of predetermined magnitude has occurred by determining if the ratio of A_n to C_n exceeds a predetermined magnitude.

11. A method for detecting a burst in an incoming signal comprising:

monitoring short-term signal strength changes in the incoming signal to determine if a short-term change in signal strength of predetermined magnitude has occurred;

monitoring long-term signal strength changes in the incoming signal to determine if a long-term change in signal strength of predetermined magnitude has occurred;

monitoring patterns of symbols in the incoming signal to determine if a predetermined pattern is present;

performing the foregoing three monitoring steps in parallel;

signaling detection of a burst if a short-term signal strength change of predetermined magnitude has occurred, a long-term signal strength change of predetermined magnitude has occurred, and a predetermined pattern of symbols is present;

detecting symbols, or estimates thereof, in the incoming signal, and monitoring the symbols or estimates to determine if a predetermined pattern of symbols is present;

wherein the incoming signal is a quadrature baseband signal, and the method further comprises determining soft estimates δ

θ

_n of the symbols; and

determining, responsive to the samples δ

θ

_n, δ

δ

θ

_n=δ

θ

_n−

δ

θ

_n-L, where L is the number of samples/symbol.

12. The method of claim 11 further comprising determining if a predetermined pattern of symbols is present responsive to the values δ

δ

_n.