Methods and apparatus for two-stage ACK/DTX detection

1. A method, comprising:

determining a first stage DTX value from bit-domain correlation values;

determining a second stage DTX value from symbol domain correlation values; and

determining a DTX decision based on the first stage DTX value and the second stage DTX value.

2. The method of claim 1 , further comprising computing a bit-domain maximum correlation value and a sub maximum correlation value as the bit-domain correlation values.

3. The method of claim 2 , further comprising:

setting the first stage DTX value to a first state when a difference between the bit-domain maximum correlation value and the sub maximum correlation value is less than a threshold; and

setting the first stage DTX value to a second state when the difference between the bit-domain maximum correlation value and the sub maximum correlation value is not less than a threshold.

4. The method of claim 1 , further comprising generating Top-M candidate ACKS from descrambled symbols.

5. The method of claim 4 , further comprising re-generating Top-2 candidate symbols from the Top-M candidate ACKS.

6. The method of claim 5 , calculating a re-generating maximum correlation value and a re-generated sub maximum correlation value from the Top-2 candidate symbols.

7. The method of claim 6 , computing a difference between the re-generated maximum correlation value and the re-generated sub maximum correlation value.

8. The method of claim 7 , further comprising:

setting the second stage DTX value to a first state when the difference between the re-generated maximum correlation value and the re-generated sub maximum correlation value is less than a threshold; and

setting the second stage DTX value to a second state when the difference between the re-generated maximum correlation value and the re-generated sub maximum correlation value is not less than a threshold.

9. The method of claim 8 , further comprising determining the DTX decision based on the first stage DTX value and the second stage DTX value using majority logic.

10. The method of claim 9 , wherein a DTX transmission is determined when both of the first stage DTX value and the second stage DTX value indicate the DTX transmission.

11. An apparatus, comprising:

bit-domain decision logic that determines a first stage DTX value from bit-domain correlation values;

symbol domain decision logic that determines a second stage DTX value from symbol domain correlation values; and

DTX decision logic that determines a DTX decision based on the first stage DTX value and the second stage DTX value.

12. The apparatus of claim 11 , wherein the bit-domain decision logic computes a bit-domain maximum correlation value and a sub maximum correlation value as the bit-domain correlation values.

13. The apparatus of claim 12 , wherein the bit-domain decision logic sets the first stage DTX value to a first state when a difference between the bit-domain maximum correlation value and the sub maximum correlation value is less than a threshold, and sets the first stage DTX value to a second state when the difference between the bit-domain maximum correlation value and the sub maximum correlation value is not less than a threshold.

14. The apparatus of claim 11 , further comprising a bit extractor/deinterleaver that generates Top-M candidate ACKS from descrambled symbols.

15. The apparatus of claim 14 , further comprising a symbol regenerator that re-generates Top-2 candidate symbols from the Top-M candidate ACKS.

16. The apparatus of claim 15 , further comprising a correlation calculator that calculates a re-generating maximum correlation value and a re-generated sub maximum correlation value in symbol domain.

17. The apparatus of claim 16 , wherein the symbol domain decision logic computes a difference between the re-generated maximum correlation value and the re-generated sub maximum correlation value.

18. The apparatus of claim 17 , wherein the symbol domain decision logic sets the second stage DTX value to a first state when the difference between the re-generated maximum correlation value and the re-generated sub maximum correlation value is less than a threshold, and sets the second stage DTX value to a second stats when the difference between the re-generated maximum correlation value and the re-generated sub maximum correlation value is not less than a threshold.

19. The apparatus of claim 18 , wherein the DTX decision logic determines the DTX decision based on the first stage DTX value and the second stage DTX value using majority logic.

20. The apparatus of claim 19 , wherein the DTX decision logic determines that a DTX transmission is received when both of the first stage DTX value and the second stage DTX value indicate the DTX transmission.