Power control protocol for highly variable data rate reverse link of a wireless communication system

• US 20070140174A1
• Filed: 02/13/2007
• Published: 06/21/2007
• Est. Priority Date: 09/21/1998
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Proctor, James
• Granted Patent: US 7,701,903 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/287 when the channel is in stand-by
• CPC Class Codes: H04W 52/288 taking into account the usage mode, e.g. hands-free, data transmission, telephone
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 52/58 Format of the TPC bits

Abstract

A technique for implementing closed loop power control in a wireless system using a modulation that requires synchronization over the radio channel, which dynamically assigns coded channels on a demand basis. The technique maintains a proper power level, even when no traffic channels are allocated, by determining a link quality metric based upon the reverse link power received. This determination is made in response to a heartbeat signal sent at a rate which is only sufficiently fast to maintain code phase lock, for example, depending upon the expected maximum rate at which the subscriber unit will travel.

Claims

1. A method for providing power control over dynamically assigned reverse link channels in a wireless communication system, the method comprising:

allocating a reverse link channel to a code division multiple access (CDMA) user device;

transmitting a message from the CDMA user device to a base station over the reverse link channel wherein the CDMA user device is powered on but not actively sending data;

determining a link quality metric for the transmitted message received at the base station; and

transmitting a power control bit from the base station to the CDMA user device wherein the power control bit is used to control the transmit power level of the CDMA user device.

2. The method of claim 1 wherein the allocated reverse link channel is the only traffic channel allocated to the CDMA user device.

3. The method of claim 1 wherein the transmission rate of the message from the CDMA user device depends on the maximum expected rate of physical movement of the CDMA user device.

4. The method of claim 1 wherein the link quality metric indicates a bit error measurement.

5. The method of claim 1 wherein the link quality metric indicates a noise level measurement.

6. The method of claim 1 wherein the link quality metric indicates a signal power level measurement.

7. The method of claim 1 wherein the step of determining the link quality metric for the transmitted message is performed at the base station.

8. The method of claim 1 wherein the power control bit is transmitted on a forward link paging channel to the CDMA user device.

9. The method of claim 1 wherein the power control bit is transmitted on a sync channel to the CDMA user device.

10. The method of claim 1 wherein the power control bit is transmitted on a pilot channel to the CDMA user device.

11. The method of claim 1 wherein the power control bit controls the transmission power level of the CDMA user device over the reverse traffic channel.

12. The method of claim 1 wherein the wireless communication system provides for the transmission of digital signals over at least one radio frequency channel via radio signals.

13. The method of claim 12 wherein each radio frequency channel comprises a plurality of subchannels wherein a plurality of different codes are assigned for each subchannel.

14. A wireless communication system for providing power control over dynamically assigned reverse link channels, the system comprising:

a plurality of code division multiple access (CDMA) user devices, each user device comprising;

an antenna;

a CDMA transceiver configured to transmit a message to a base station over a reverse link channel and to receive a power control bit from the base station; and

a controller configured to maintain the reverse link channel between a particular CDMA user device and the base station;

at least one base station, the base station comprising;

a plurality of multichannel antennas;

a controller configured to allocate the reverse link channel between the particular CDMA user device and the base station and to determine a link quality metric for the received message transmitted from each CDMA user device; and

a plurality of CDMA transceivers configured to receive the message from the particular CDMA user device over the reverse link channel and to transmit the power control bit to the particular CDMA user device.

15. The system as in claim 14 wherein the plurality of CDMA user devices lack any other allocated traffic channels.

16. The system as in claim 14 wherein the transmission rate of the message depends on the maximum expected rate of physical movement of each CDMA user device.

17. The system as in claim 14 wherein the link quality metric indicates a bit error measurement.

18. The system as in claim 14 wherein the link quality metric indicates a noise level measurement.

19. The system as in claim 14 wherein the link quality metric indicates a signal power level measurement.

20. The system as in claim 14 wherein the power control bit is transmitted on a forward link paging channel to the CDMA user device.

21. The system as in claim 14 wherein the power control bit is transmitted on a sync channel to the CDMA user device.

22. The system as in claim 14 wherein the power control bit is transmitted on a pilot channel to the CDMA user device.

23. The system as in claim 14 wherein the power control bit controls the transmission power level of the CDMA user device over the reverse traffic channel.

24. The system as in claim 14 wherein the wireless communication system provides for the transmission of digital signals over at least one radio frequency channel via radio signals.

25. The system as in claim 23 wherein each radio frequency channel comprises a plurality of subchannels by assigning a plurality of different codes for each subchannel.