Method and apparatus for controlling transmission power in a CDMA communication system

• US 6,788,685 B1
• Filed: 01/28/1999
• Issued: 09/07/2004
• Est. Priority Date: 01/28/1999
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Tao, Holtzman, Jack M., Razoumov, Leonid
• Primary Examiner(s): Ho, Duc
• Assistant Examiner(s): Nguyen, Phuongchau Ba
• Application Number:
  US09/239,451
• Time in Patent Office: 2,049 Days
• Field of Search: 370/337, 370/347, 370/318, 370/442, 370/335, 370/458, 370/342, 370/391, 455/69, 455/63, 455/522, 375/342
• US Class Current: 370/391
• CPC Class Codes: H04W 52/267 taking into account the information rate
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands

Abstract

Method and apparatus for controlling transmission power in a closed loop power control system, wherein power control commands are based on the energy of the previous power control commands. In one embodiment, the method compares changes in the received energy of received power control commands against expected changes in those commands based on previously transmitted power control commands, and identifies suspicious responses to said previously transmitted power control commands. Hypothesis testing of the received power control commands is performed accordance any identified suspicious responses.

Claims

1. In a communication system including a transmitter for transmitting a first type of data and a second type of data wherein the second type of data is punctured into the first type of data, and wherein the transmission energy of said first type of data is varied in accordance upon the rate of said first type of data and wherein the transmission energy of said second type of data does not vary in accordance with the rate of said first type of data, a power control system for controlling the transmission energy of said first type of data and said second type of data comprising:

receiver means for receiving said first type of data and said second type of data;

de-multiplexer means for separating said second type of data from said first type of data;

means for measuring an energy of said second type of data to provide an indication of an energy of said second type of data as received at the receiver means; and

power control processor means for receiving said indication of the energy of said second type of data and for generating a power control command for said transmission energy of said first type of data in accordance with said indication of the energy of said second type of data.

2. The power control system of claim 1 wherein said first type of data comprises variable rate traffic data and wherein said second type of data comprises power control commands.

3. The power control system of claim 2 further comprising filter means for filtering a plurality of said received power control commands to provide an improved estimate of the received energy of said power control commands.

4. The power control system of claim 3 further comprising power control bit processor for adjusting the energies of said received power control commands to compensate for energy adjustments made at said transmitter in response to a set of previously transmitted power control commands.

5. The power control system of claim 4 wherein said power control processor is further for estimating a most likely sequence of power control commands responded to by said transmitter.

6. The power control system of claim 5 wherein said power control processor estimates the power control commands received by said transmitter and adjusts the energies of said received power control commands to compensate for energy adjustments made at said transmitter in response to said estimates the power control commands received by said transmitter.

7. The power control system of claim 6 wherein said power control processor estimates said most likely sequence of power control commands responded to by said transmitter by:

comparing changes in the received energy of said received power control commands against expected changes in those commands based on said set of previously transmitted power control commands;

identifying suspicious responses to said previously transmitted power control commands; and

testing a set of hypotheses of receive power control commands in accordance with said identified suspicious responses.

8. The power control system of claim 1 wherein said first type of data comprises variable rate traffic data.

9. The power control system of claim 8 further comprising filter means for filtering a set of said second type of data over a plurality of received frames to provide an improved estimate of the received energy of said second type of data.

10. The power control system of claim 9 further comprising procesor means for adjusting the energies of said second type of data to compensate for energy adjustments made at said transmitter in response to a set of previously transmitted power control commands.

11. The power control system of claim 10 wherein said processor means is further for estimating a most likely sequence of power control commands responded to by said transmitter.

12. The power control system of claim 11 wherein said processor means estimates the power control commands received by said transmitter and adjusts the energies of said set of said second type of data over a plurality of received frames to compensate for energy adjustments made at said transmitter in response to said estimates the power control commands received by said transmitter.

13. The power control system of claim 12 wherein said power control processor estimates said most likely sequence of power control commands responded to by said transmitter by:

comparing changes in the received energy of said received power control commands against expected changes in those commands based on said set of previously transmitted power control commands;

identifying suspicious responses to said previously transmitted power control commands; and

testing a set of hypotheses of receive power control commands in accordance with said identified suspicious responses.

14. The power control system of claim 2 further comprising filter means for filtering a plurality of said received power control commands to provide an improved estimate of the received energy of said power control commands and wherein said filter means generates a filtered power control bit energy in accordance with the equation:

${\hat{P}}_N=\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\mathrm{\beta <br><br>}}_i<br><br>\left(\frac{T_N}{T_i}\right)<br><br>P_i,$

where Ti is the traffic energy for ith power control group, Pi is the power control bit energy of the ith power control group, and β

is a weighting function.

15. The power control system of claim 14 wherein said weighting function, β

_i, is determined in accordance with the equation;

${\mathrm{\beta <br><br>}}_i=\frac{T_i}{\underset{n=1}{\overset{N}{\sum <br><br>}}<br><br>T_n}.$

16. In a communication system including a transmitter for transmitting a first type of data and a second type of data wherein the second type of data is punctured into the first type of data, and wherein the transmission energy of said first type of data is varied in accordance upon the rate of said first type of data and wherein the transmission energy of said second type of data does not vary in accordance with the rate of said first type of data, a method for controlling the transmission energy of said first type of data and said second type of data comprising:

receiving said first type of data and said second type of data;

de-multiplexing said second type of data from said first type of data;

measuring an energy of said second type of data to form a measured energy; and

generating a power control command for said transmission energy of said first type of data in accordance with said measured energy.

17. The method of claim 16 wherein said first type of data comprises variable rate traffic data and wherein said second type of data comprises power control symbols.

18. The power control system of claim 17 further comprising the step of filtering the measured energy of a plurality of said received power control symbols to provide an improved estimate of the received energy of said power control symbols.

19. The method of claim 18 further comprising the step of adjusting the energies of said received power control symbols to compensate for energy adjustments made at said transmitter in response to a set of previously transmitted power control commands.

20. The method of claim 19 further comprising the step of estimating the most likely sequence of power control commands responded to by said transmitter.

21. The method of claim 20 further comprising the step of compensating for energy adjustments made at said transmitter in response to said estimates the power control commands received by said transmitter.

22. The method of claim 21 wherein said step of estimating the most likely sequence of power control commands responded to by said transmitter, comprises the steps of:

comparing changes in the received energy of said received power control commands against expected changes in those commands based on said set of previously transmitted power control commands;

identifying suspicious responses to said previously transmitted power control commands; and

testing a set of hypotheses of receive power control commands in accordance with said identified suspicious responses.

23. The method of claim 16 wherein said first type of data comprises variable rate traffic data.

24. The method of claim 23 further comprising the step of filtering a set of said second type of data over a plurality of received frames to provide an improved estimate of the received energy of said second type of data.

25. The method of claim 24 further comprising adjusting the energies of said second type of data to compensate for energy adjustments made at said transmitter in response to a set of previously transmitted power control commands.

26. The method of claim 25 wherein said processor means is further for estimating a most likely sequence of power control commands responded to by said transmitter.

27. The method of claim 26 further comprising the steps of:

estimating the power control commands received by said transmitter; and

adjusting the energies of said set of said second type of data over a plurality of received frames to compensate for energy adjustments made at said transmitter in response to said estimates the power control commands received by said transmitter.

28. The method of claim 27 wherein said step of estimating the power control commands received by said transmitter, comprises the steps of:

comparing changes in the received energy of said received power control commands against expected changes in those commands based on said set of previously transmitted power control commands;

identifying suspicious responses to said previously transmitted power control commands; and

testing a set of hypotheses of receive power control commands in accordance with said identified suspicious responses.

29. The method of claim 17 further comprising the step of filtering a plurality of said received power control commands to provide an improved estimate of the received energy of said power control commands and wherein said filter means generates a filtered power control bit energy in accordance with the equation:

${\hat{P}}_N=\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>{\mathrm{\beta <br><br>}}_i<br><br>\left(\frac{T_N}{T_i}\right)<br><br>P_i,$

where Ti is the traffic energy for ith power control group, Pi is the power control bit energy of the ith power control group, and β

is a weighting function.

30. The method of claim 29 wherein said weighting function β

_i, is determined in accordance with the equation;

${\mathrm{\beta <br><br>}}_i=\frac{T_i}{\underset{n=1}{\overset{N}{\sum <br><br>}}<br><br>T_n}.$