US 7,254,200 B2Granted

System and method for frequency burst detection for GSM/GPRS

AssigneeHellosoft, Inc.

InventorsGottimukkala Narendra Varma, Usha Sahu, Garapati Prabhu Charan

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Abstract

A system, method and computer program product for detecting a frequency burst in a received signal at a wireless receiver is disclosed. The invention predicts the current sample of the received signal by filtering the past samples of the received signal through an adaptive filter. A prediction error is further obtained by subtracting the actual current sample and the predicted current sample. The prediction error is then used to adapt the adaptive filter. Since the frequency burst is a substantially predictable signal, the adaptive filter adapts to accurately predict the samples of the frequency burst. Therefore, the prediction error decreases when the frequency burst is received at the receiver. The end of the frequency burst is identified using the prediction error at each discrete time instant.

Claims20

Dependent claims

A method for detecting a complex frequency burst in a received complex signal at a wireless receiver, the complex frequency burst having a known length, the method comprising the steps of:

a. filtering past samples of the received complex signal using a complex signal based adaptive filter to obtain a filtered current sample of the received complex signal;
b. obtaining a complex error between the filtered current sample of the received complex signal and an actual current sample of the received complex signal;
c. adapting the adaptive filter using the complex error;
and
d. locating the complex frequency burst using the complex error, wherein the step of locating the complex frequency burst using the complex error comprises the steps of:
if a previous sample of the received complex signal is established to belong to the complex frequency burst, then performing the step of:
analyzing the complex error to establish whether the previous sample of the received complex signal is a last sample of the complex frequency burst;
and
if the previous sample of the received complex signal is not established as the last sample of the complex frequency burst, then performing the step of:
establishing that the current sample of the received complex signal belongs to the complex frequency burst;
and
if the previous sample of the received complex signal is not established to belong to the complex frequency burst, then performing the step of:
analyzing the complex error to establish whether the current sample of the received complex signal belongs to the complex frequency burst.

10 more elements

A system for detecting a complex frequency burst in a received complex signal at a wireless receiver, the system comprising:

a. a complex signal based adaptive filter filtering past samples of the received complex signal to obtain a filtered current sample of the received complex signal;
b. a summation unit obtaining a complex error using the filtered current sample of the received complex signal and an actual current sample of the received complex signal;
c. an adapting unit adapting the complex signal based adaptive filter using the complex error;
and
d. a complex frequency burst detector locating the complex frequency burst using the complex error, wherein the complex frequency burst detector comprises:
i. a complex frequency burst presence flag for recording whether a previous sample of the received complex signal is established to belong to the complex frequency burst;
ii. an inaccuracy calculator calculating an inaccuracy parameter using the complex error and setting the complex frequency burst presence flag if the inaccuracy parameter is less than an error power threshold;
iii. a ratio calculator calculating an error power parameter using the complex error and obtaining a ratio of the error power parameter and the inaccuracy parameter if the complex frequency burst presence flag is set;
and
iv. an end detector establishing whether the previous sample of the received complex signal is the last sample of the complex frequency burst using the obtained ratio and resetting the flag if the previous sample of the received complex signal is the last sample of the complex frequency burst.

7 more elements

Dependencies are inferred from the claim text.