Methods for power reduction detection for enhanced dedicated channel

1. A method for detecting transmission power reduction in a physical channel at a receiver, the physical channel including at least a non-enhanced data channel portion, a non-enhanced control channel portion associated with the non-enhanced data channel portion, an enhanced data channel portion and an enhanced control channel portion associated with the enhanced data channel portion, the enhanced data channel portion for carrying higher data rate data than the non-enhanced data channel portion, the method comprising:

estimating a ratio of a transmission power associated with the enhanced data channel portion to transmission power associated with the non-enhanced control channel portion based on channel estimates associated with the non-enhanced control channel portion and a decoded signal portion received on the enhanced data channel portion;

comparing the estimated ratio with a first threshold, the first threshold being determined based on a format indicator associated with the enhanced data channel portion; and

detecting a transmission power reduction in the enhanced data channel portion based on the comparing step.

2. The method of claim 1 , wherein the detecting step detects the transmission power reduction if the estimated transmission power is less than the first threshold.

3. The method of claim 1 , wherein the first threshold is a reference ratio of enhanced data channel portion transmission power to the non-enhanced control channel portion transmission power.

4. The method of claim 1 , further comprising:

setting a power reduction detection flag if the detecting step detects a transmission power reduction, the power reduction flag indicating that the transmission power associated with the enhanced data channel portion has been decreased; and

receiving data transmitted on the enhanced data channel at a reduced transmission power if the setting step sets the power reduction detection flag.

5. The method of claim 1 , wherein the detecting step detects the transmission power reduction if the estimated transmission power is less than the threshold.

6. The method of claim 1 , wherein the threshold is a reference ratio of enhanced data channel transmission power to control channel transmission power.

7. The method of claim 1 , further comprising:

generating the channel estimates associated with the non-enhanced control channel portion based on a received signal; and

decoding an enhanced data channel portion of the received signal to generate the decoded signal portion; wherein

the estimating step estimates the ratio based on the channel estimates and the decoded signal portion.

8. The method of claim 7 , wherein the estimating step further comprises:

squaring and accumulating the decoded signal portion over a first time interval to generate a first estimated transmission power, the first estimated transmission power being associated with the enhanced data channel portion;

squaring and accumulating the channel estimates over a first time interval to generate a second estimated transmission power, the second estimated transmission power being associated with the non-enhanced control channel portion; and

estimating the ratio based on the first and second estimated transmission powers.

9. The method of claim 8 , wherein the estimating step estimates the ratio by dividing the first estimated transmission power by the second estimated transmission power.

10. The method of claim 1 , further comprising:

comparing the estimated ratio with a second threshold, the second threshold; and

detecting a discontinuous transmission in the non-enhanced control channel portion based on the comparing step.

11. The method of claim 1 , wherein the estimating step estimates the ratio based on the channel estimates associated with the non-enhanced control channel portion, the decoded signal portion and data recovered based on the decoded signal portion.

12. The method of claim 11 , wherein the decoded signal portion is an enhanced data channel portion of the decoded signal.

13. The method of claim 11 , wherein the detecting step detects the transmission power reduction if the estimated transmission power is less than the threshold.

14. The method of claim 11 , wherein the threshold is a reference ratio of enhanced data channel transmission power to control channel transmission power.

15. The method of claim 11 , further comprising:

generating the channel estimates associated with the non-enhanced control channel portion based on a received signal;

decoding an enhanced data channel portion of the received signal to generate the decoded signal portion;

recovering transmitted data based on the channel estimates, control information associated with the enhanced control channel portion and the decoded signal portion; and

re-encoding the recovered data; wherein the estimating step estimates the ratio based on the channel estimates, the decoded signal portion and the re-encoded data.

16. The method of claim 11 , wherein the estimating step further comprises:

combining the decoded signal portion and the re-encoded data to generate a first composite signal energy;

accumulating the first composite signal energy over a first time interval;

squaring the accumulated first composite signal energy to generate a first estimated transmission power, the first estimated transmission power being associated with the enhanced data channel portion;

squaring and accumulating the channel estimates over a first time interval to generate a second estimated transmission power, the second estimated transmission power being associated with the non-enhanced control channel portion; and

estimating the ratio based on the first and second estimated transmission powers.

17. The method of claim 16 , wherein the estimating step estimates the ratio by dividing the first estimated transmission power by a square of the second estimated transmission power to generate the ratio.

18. The method of claim 11 , further comprising:

comparing the estimated ratio with a second threshold; and

detecting whether data is being transmitted on the enhanced data channel portion based on the comparing step; and

receiving transmitted data on the enhanced data channel if the detecting step detects transmitted data.

19. A transmission power reduction detector for detecting a transmission power reduction in a physical channel at a receiver, the physical channel including at least a non-enhanced data channel portion, a non-enhanced control channel portion associated with the non-enhanced data channel portion, an enhanced data channel portion and an enhanced control channel portion associated with the enhanced data channel portion, the enhanced data channel portion for carrying higher data rate data than the non-enhanced data channel portion, the detector comprising:

an estimation block configured to estimate a ratio of a transmission power associated with the enhanced data channel portion to transmission power associated with the non-enhanced control channel portion based on channel estimates associated with the non-enhanced control channel portion and a decoded signal portion received on the enhanced data channel portion;

a comparing block configured to compare the estimated ratio with a threshold, the threshold being determined based on a format indicator associated with the enhanced data channel portion; wherein the detector is configured to detect a transmission power reduction in the enhanced data channel based on the comparison of the estimated ratio with a threshold.