System and method to perform DC compensation on a radio frequency burst in a cellular wireless network

1. A method to perform direct current (DC) compensation on an RF burst, wherein the RF burst is transmitted between a servicing base station and a wireless terminal, the method comprising: using an enCOder/DECoder (CODEC) processing module for: receiving the RF burst, wherein the RF burst is modulated according to either a first modulation format or a second modulation format;

producing a plurality of samples from the RF burst;

averaging at least some of the plurality of samples to produce a DC offset estimate;

subtracting the DC offset estimate from each of the plurality of samples to produce a plurality of DC offset estimate subtracted samples;

identifying the modulation format of the RF burst from the plurality of DC offset estimate subtracted samples;

when the first modulation format is identified, demodulating the plurality of DC offset estimate subtracted samples;

when the second modulation format is identified:

adding the DC offset estimate to each of the plurality of DC offset estimate subtracted samples to produce a plurality of adjusted samples; and

demodulating the plurality of adjusted samples.

2. The method of claim 1 , wherein:

the first modulation format is Gaussian Minimum Shift Keying (GMSK) modulation; and

the second modulation format is Light Phase Shift Keying (8PSK) modulation.

3. The method of claim 1 , wherein producing the plurality of samples from the RF burst, further comprises:

processing the RF burst to produce a baseband signal;

extracting a training sequence from the baseband signal, wherein the training sequence comprises In-phases (I) and Quadrature (Q) phases; and

sampling the training sequence to produce the plurality of samples, wherein the samples comprise both I phases and Q phases, and wherein the plurality of samples taken over the training sequence are averaged to produce the DC offset estimate.

4. The method of claim 1 , wherein the DC offset estimate comprises:

an I phase DC offset estimate; and

a Q phase DC offset estimate.

5. The method of claim 1 , wherein the DC offset estimate is based upon all samples of the RF burst.

6. The method of claim 1 , further comprising:

receiving a subsequent RF burst within the data frame from the servicing base station, wherein the subsequent RF burst carries a plurality of modulated symbols;

determining a first accumulated result from processing the subsequent RF burst and prior RF bursts according to the first modulation format;

determining a second accumulated result from processing the subsequent RF burst and prior RF bursts according to the second modulation format;

comparing the first accumulated result and the second accumulated result to determine the more favorable accumulated result;

identifying the modulation format associated with the subsequent RF burst based as the modulation format corresponding to the more favorable accumulated result;

demodulating the subsequent RF burst according to the identified modulation format; and

discarding the RF burst when the identified modulation format of the subsequent RF burst compares unfavorably to the identified modulation format of prior RF bursts.

7. The method of claim 1 , further comprising: receiving a subsequent RF burst within the data frame from the servicing base station, wherein the subsequent RF burst carries a plurality of modulated symbols;

determining a first accumulated result from processing the subsequent RF and prior RF bursts according to the first modulation format;

determining a second accumulated result from processing the subsequent RF burst and prior RF bursts according to the second modulation format;

comparing the first accumulated result and the second accumulated result to determine the more favorable accumulated result;

identifying the modulation format associated with the subsequent RF burst based as the modulation format corresponding to the more favorable accumulated result;

demodulating the subsequent RF burst according to the identified modulation format; and

reprocessing the RF burst when the identified modulation format of the subsequent RF burst compares unfavorably to the identified modulation format of prior RF bursts.

8. An RF burst processing module that comprises:

an enCOder/DECoder (CODEC) processing that is operable to:

receive an RF burst, wherein the RF burst is modulated according to either a first modulation format or a second modulation format;

produce a plurality of samples from the RF burst;

average the plurality of samples to produce a direct current (DC) offset estimate;

subtract the DC offset estimate from each of the plurality of samples to produce a plurality of DC offset estimated subtracted samples;

identify the modulation format of the RF burst from the plurality of DC offset estimated subtracted samples;

when the first modulation format is identified, demodulate the plurality of DC offset estimate subtracted samples;

when the second modulation format is identified:

add the DC offset estimate to each of the plurality of DC offset estimated subtracted samples to produce a plurality of adjusted samples; and

demodulate the plurality of adjusted samples.

9. The RF burst processing module of claim 8 , wherein:

the first modulation format is Gaussian Minimum Shift Keying (GMSK) modulation; and

the second modulation format is Eight Phase Shift Keying (8PSK) modulation.

10. The RF burst processing module of claim 8 , wherein the CODEC processing module is further operable to:

process the RF burst to produce a baseband signal;

extract a training sequence from the baseband signal, wherein the training sequence comprises In-phases (I) and Quadrature (Q) phases; and

sample the training sequence to produce the plurality of samples, wherein the samples comprise both I phases and Q phases, and wherein the plurality of samples taken over the training sequence are averaged to produce the DC offset estimate.

11. The RF burst processing module of claim 8 , wherein the DC offset estimate comprises:

an I phase DC offset estimate; and

a Q phase DC offset estimate.

12. The RF burst processing module of claim 8 , wherein the CODEC processing module is further operable to:

receive a subsequent RF burst within the data frame from the servicing base station, wherein the subsequent RF burst carries a plurality of modulated symbols;

determine a first accumulated result from processing the subsequent RF burst and prior RF bursts according to the first modulation format;

determine a second accumulated result from processing the subsequent RF burst and prior RF bursts according to the second modulation format;

compare the first accumulated result and the second accumulated result to determine the more favorable accumulated results;

identify the modulation format associated with the subsequent RF burst based as the modulation format corresponding to the more favorable accumulated result;

demodulate the subsequent RF burst according to the identified modulation format; and

discard the first RF burst when the identified modulation format of the subsequent RF burst compares unfavorably to the identified modulation format of the prior RF bursts.

13. The RF burst processing module of claim 8 , wherein, the CODEC processing module is further operable to:

receive a subsequent RF burst within the data frame from the servicing base station, wherein the subsequent RF burst carries a plurality of modulated symbols;

determine a first accumulated result from processing the subsequent RF burst and prior RF bursts according to the first modulation format;

determine a second accumulated result from processing the subsequent RF burst and prior RF bursts according to the second modulation format;

compare the first accumulated result and the second accumulated result to determine the more favorable accumulated results;

identify the modulation format associated with the subsequent RF burst based as the modulation format corresponding to the more favorable accumulated result;

demodulate the subsequent RF burst according to the identified modulation format; and

reprocess the first RF burst according to the modulation format identified with the subsequent RF burst when the modulation format identified with the subsequent RF burst compares unfavorably to the modulation format identified with the first RF burst.

14. The RF burst processing module of claim 8 , wherein the RF burst processing module is within a wireless terminal that operates according to the Global System for Mobile telecommunications (GSM) standard.

15. A communication terminal that comprises:

an RF front end operable to receive an RF burst;

a baseband processor communicatively coupled to the RF front end;

wherein, the RF front end and the baseband processor are operable to:

receive the RF burst, wherein the RF burst is modulated according to either a first modulation format or a second modulation format;

produce a plurality of samples from the first RF burst;

average the plurality of samples to produce a direct current (DC) offset estimate;

subtract the DC offset estimate from each of the plurality of samples;

identify the modulation format of the RF burst from the plurality of DC offset estimate subtracted samples;

add the DC offset estimate to each of the plurality of DC offset estimate subtracted samples when the second modulation format was identified as the modulation format of the RF burst; and

demodulate the RF burst according to the identified modulation format.

16. The communication terminal of claim 15 , wherein:

the first modulation format is Gaussian Minimum Shift Keying (GMSK) modulation and

the second modulation format is Eight Phase Shift Keying (8PSK) modulation.

17. The communication terminal of claim 15 , wherein, the RF front end and the baseband processor are further operable to:

process the RF burst to produce a baseband signal;

extract a training sequence from the baseband signal, wherein the training sequence comprises In-phases (I) and Quadrature (Q) phases; and

sample the training sequence to produce the plurality of samples, wherein the samples comprise both I phases and Q phases, and wherein the plurality of samples taken over the training sequence are averaged to produce the DC offset estimate.

18. The communication terminal of claim 15 , wherein the DC offset estimate comprises:

an I phase DC offset estimate; and

a Q phase DC offset estimate.

19. The communication terminal of claim 15 , wherein, the RF front end and the baseband processor are further operable to:

receive a subsequent RF burst within the data frame from the servicing base station, wherein the subsequent RF burst carries a plurality of modulated symbols;

determine a first accumulated result from processing the subsequent RF and prior RF bursts according to the first modulation format;

determine a second accumulated result from processing the subsequent RF and prior RF bursts according to the second modulation format;

compare the first accumulated result and the second accumulated result to determine the more favorable accumulated results;

identify the modulation format associated with the subsequent RF burst based as the modulation format corresponding to the more favorable accumulated result;

demodulate the subsequent RF burst according to the identified modulation format; and

discard the first RF burst according to the modulation format identified with the subsequent RF burst when the modulation format identified with the subsequent RF burst compares unfavorably to the modulation format identified with the first RF burst.

20. The communication terminal of claim 15 , wherein, the RF front end and the baseband processor are further operable to:

receive a subsequent RF burst within the data frame from the servicing base station, wherein the subsequent RF burst carries a plurality of modulated symbols;

determine a first accumulated result from processing the subsequent RF and prior RF bursts according to the first modulation format;

determine a second accumulated result from processing the subsequent RF and prior RF bursts according to the second modulation format;

compare the first accumulated result and the second accumulated result to determine the more favorable accumulated results;

identify the modulation format associated with the subsequent RF burst based as the modulation format corresponding to the more favorable accumulated result;

demodulate the subsequent RF burst according to the identified modulation format; and

reprocess the first RF burst according to the modulation format identified with the subsequent RF burst when the modulation format identified with the subsequent RF burst compares unfavorably to the modulation format identified with the first RF burst.