Method for adjusting transmitter output power

1. A method of operating a wireless multichannel CDMA transmitter, the method comprising:

generating a plurality of modulated data streams;

spreading each one of the data streams with one of a plurality of spreading factors;

multiplying each one of the spread data streams with a respective one of a plurality of power weighting factors; and

calculating a maximum power reduction for a power amplifier of the CDMA transmitter as a function of the used power weighting factors.

2. The method of claim 1 , further comprising:

determining at least one approximation parameter for calculating the maximum power reduction.

3. The method of claim 2 , wherein the at least one approximation parameter is determined by a comparison of an approximated maximum power reduction with a metric for the maximum power reduction.

4. The method of claim 3 , wherein the at least one approximation parameter is determined by minimizing the difference between the approximated maximum power reduction and the metric for the maximum power reduction.

5. The method of claim 2 , wherein an iterative method is used for determining the at least one approximation parameter.

6. The method of claim 3 , wherein the approximated maximum power reduction and the metric for the maximum power reduction are computed using a test signal.

7. The method of claim 6 , wherein the test signal is different from the signal formed from the plurality of data streams.

8. The method of claim 2 , wherein the at least one approximation parameter is determined before the generation of a plurality of data streams.

9. A method in a wireless multichannel CDMA transmitter, the method comprising:

configuring the wireless multichannel CDMA transmitter for a particular signal configuration using a test signal that reflects a transmit signal for the particular signal configuration;

adjusting transmitter headroom based on the particular configuration, wherein the headroom is adjusted as a function of power weighting factors used in the channels of the particular signal configuration.

10. A method in a wireless multichannel CDMA transmitter, the method comprising:

configuring the wireless multichannel CDMA transmitter for a particular signal configuration;

adjusting transmitter headroom based on the particular configuration, wherein the headroom is adjusted as a function of power weighting factors used in the channels of the particular signal configuration;

defining a power metric for calculating a maximum power reduction for all possible signal configurations of the CDMA transmitter; and

defining an approximation of the power metric.

11. The method of claim 10 , further comprising:

calculating the maximum power reduction from the approximation of the power metric.

12. The method of claim 11 , wherein at least one approximation parameter is determined for the approximation of the power metric.

13. The method of claim 12 , wherein the at least one approximation parameter is determined individually for a particular signal configuration.

14. The method of claim 13 , wherein the at least one parameter for the particular signal configuration is determined before configuring the wireless multichannel CDMA transmitter for the particular signal configuration.

15. The method of claim 14 , wherein the transmitter headroom is adjusted based on the stored approximation parameter which has been determined particularly for the particular signal configuration.

16. The method of claim 13 , wherein the at least one approximation parameter is determined and stored in a memory for a plurality of different signal configurations.

17. A method in a wireless multichannel CDMA transmitter, the method comprising:

determining a maximum power reduction based on a particular signal configuration of the transmitter, a property of the particular signal configuration comprising at least one of spreading factors used for the respective signals and power weighting factors used for the respective signals, wherein the maximum power reduction is determined as a function of the particular signal configuration; and

adjusting transmitter output power based on the maximum power reduction.

18. A method in a wireless multichannel CDMA transmitter, the method comprising:

determining a metric based on a particular signal configuration of the transmitter, wherein the metric is determined as a function of the particular signal configuration; and

adjusting transmitter output power based on the metric;

selecting a set of second signal configurations, comprising at least one signal configuration; and

calculating a value for each signal configuration of the set of second signal configurations from the metric.

19. The method of claim 18 , wherein the metric is a measure of the difference between the particular signal configuration and the respective one of the set of second signal configurations.

20. The method of claim 19 , further comprising:

calculating a maximum power reduction for at least a subset of the set of second signal configurations;

determining a maximum power reduction for the particular signal configuration from weighting the calculated maximum power reduction values with the values calculated from the metric.