Enhanced reverse link power control in a wireless communication system

• US 5,896,411 A
• Filed: 12/26/1997
• Issued: 04/20/1999
• Est. Priority Date: 05/05/1997
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Ali, Farhan, Gutierrez, Alberto, Chang, Kim, Huang, Chenhong, Manning, Serge
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHAYOUR, MOHAMMAD H
• Application Number:
  US08/998,542
• Time in Patent Office: 480 Days
• Field of Search: 375/200, 455/522, 455/69, 455/68
• US Class Current: 375/130
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/282 taking into account the speed of the mobile
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/58 Format of the TPC bits

Abstract

An enhanced mechanism for the reverse link power control in a wireless communication system, especially for high speed data applications and fixed wireless communication applications, dynamically adjusts the power control step size of the reverse link power control. The power control step size is dynamically adjusted based on various factors including types of service, number of reverse supplemental code channels, total received power at the base station, estimated diversity gain and required mobility, among others. The system which includes stationary infrastructure, can query a subscriber unit'"'"'s capability in the support of a pre-defined set of power control step sizes before assigning it to the subscriber unit. Furthermore, the subscriber unit may decide its optimized power control step size based on certain feedbacks from the system. In a specific embodiment, enhancement to the ANSI EIA/TIA-95 system is provided such that it supports a variable subscriber unit power control step size and associated signaling in accord with this invention.

Claims

1. A wireless communication system serving at least one subscriber unit operating within a respective service, the wireless communication system comprising:

a base station that provides wireless coverage within the service area, the base station establishing a forward link and a reverse link with the subscriber unit, communications transmitted to the subscriber unit on the forward link and communications received from the subscriber unit on the reverse link;

the base station, based upon system conditions and reverse link power control step sizes supported by the subscriber unit, selecting a reverse link power control step size for the subscriber unit;

the base station directing the subscriber unit to make adjustments to the power level of reverse link transmissions by a selected power control step size; and

based upon the power level of reverse link transmissions from the subscriber unit received by the base station, the base station periodically directing the subscriber unit to increment or decrement the power level of reverse link transmissions by the selected power control step size in an attempt to cause the reverse link transmissions to arrive at the base station at a desired power level.

2. The wireless communication system of claim 1, the wireless communication system operating according to a Code Division Multiple Access mechanism.

3. The wireless communication system of claim 1, wherein the subscriber unit is capable of supporting multiple power control step sizes.

4. The wireless communication system of claim 1, wherein the base station queries the subscriber unit regarding its capabilities to support multiple power control step sizes by exchanging messages with the subscriber unit.

5. The wireless communication system of claim 1, wherein the system conditions include the power level and quality of the signal received by the base station from the subscriber unit.

6. The wireless communication system of claim 1, wherein the system conditions include the type of service being provided to the subscriber unit.

7. The wireless communication system of claim 1, wherein the system conditions include the mobility characteristics of the subscriber unit.

8. The wireless communication system of claim 1, wherein communications received by the base station from the subscriber unit are over a high speed data link comprised of a plurality of reverse link code channels.

9. The wireless communication system of claim 8, wherein the system conditions include the number of reverse link code channels received by the base station from the subscriber unit.

10. The wireless communication system of claim 1, wherein the base station directs the subscriber unit to adjust the power control step size via a power control message.

11. The wireless communication system of claim 1, wherein:

a plurality of subscriber units communicate with the base station via respective forward links and respective reverse links;

for each of the plurality of subscriber units, based upon system conditions and reverse link power control step sizes supported by the subscriber unit, the base station selecting a respective power control step size for the subscriber unit;

for each of the plurality of subscriber units, the base station directing the subscriber unit to make adjustments to the power level of respective reverse link transmissions by a respective selected power control step size; and

for each of the plurality of subscriber units, the base station periodically directing the subscriber unit to increment or decrement its respective reverse link power transmission level by the respective selected power control step size.

12. The wireless communication system of claim 11, wherein the system conditions include the types of services being provided to the plurality of subscriber units.

13. The wireless communication system of claim 11, wherein the system conditions include the mobility characteristics of the subscriber units.

14. The wireless communication system of claim 11, wherein the system conditions include the power level and quality of the signals received by the base station from the subscriber units.

15. The wireless communication system of claim 11, wherein system conditions include the number of reverse link code channels received by the base station from the subscriber units.

25. The wireless communication system of claim 11, wherein:

the wireless communication system provides coverage to subscriber units over a plurality of service areas, each of the plurality of service areas served by at least one base station; and

at least base station directs a subscriber unit to adjust its power control step size during handoff between the plurality of service areas.

16. A subscriber unit for use with a wireless communication system comprised of at least one base station that provides wireless coverage to the subscriber unit within a service area, the subscriber unit comprising of:

a processing unit;

a radio transceiver unit coupled to the processing unit that communicates with the base station on both a forward link and a reverse link, communications received by the subscriber unit from the base station on the forward link and communications transmitted by the subscriber unit to the base station on the reverse link, the radio transceiver unit capable of incrementing or decrementing the power level of transmissions on the reverse link by a plurality of supported power control step sizes;

the subscriber unit receiving a selected power control step size from the base station that was selected by the base station based upon system conditions and the plurality of power control step sizes supported by the subscriber unit; and

the subscriber unit periodically incrementing or decrementing the power level of transmissions on the reverse link by the selected reverse link power control step, the incrementing or decrementing performed in an attempt to cause the transmissions on the reverse link to arrive at the base station at desired power levels.

17. The subscriber unit of claim 16, the wireless communication system operating according to a Code Division Multiple Access mechanism.

18. The subscriber unit of claim 16, wherein the system conditions include the power level and quality of the signal received by the base station from the subscriber unit.

19. The subscriber unit of claim 16, wherein the system conditions include the type of services being provided to the subscriber unit by the base station.

20. The subscriber unit of claim 16, wherein the system conditions include the mobility characteristics of the subscriber unit.

21. The subscriber unit of claim 16, wherein communications received by the base station from the subscriber unit are over a high speed data link comprised of a plurality of reverse link code channels.

22. The subscriber unit of claim 21, wherein the system conditions include the number of reverse link code channels comprising the high speed data link for communications received by the base station from the subscriber unit.

23. The subscriber unit of claim 16, wherein the base station directs the subscriber unit to adjust the power control step size via a power control message.

24. The subscriber unit of claim 16, wherein the base station directs the subscriber unit to adjust the power control step size via general handoff direction messages, extended channel assignment messages and supplemental channel assignment messages.

26. The subscriber unit of claim 16, wherein the subscriber unit is directed by a base station to adjust its power control step size during handoff to another service area.

27. The subscriber unit of claim 16, wherein the subscriber unit autonomously adjusts its power control step size based on system conditions.

28. A method of operating a wireless communication system that serves at least one subscriber unit operating in a service area, the method comprising:

establishing a forward link and a reverse link between a base station and a subscriber unit, communications transmitted to the subscriber unit from the base station on the forward link and communications transmitted to the base station from the subscriber unit on the reverse link;

selecting, by the base station, a power control step size for the subscriber unit based upon system conditions and power control step sizes supported by the subscriber unit;

the base station directing the subscriber unit to use the selected power control step size for subsequent adjustments of the power level of transmissions on the reverse link; and

the base station periodically directing the subscriber unit to increment or decrement the power level of transmissions on the reverse link by the selected power control step size to cause the transmissions on the reverse link to arrive at the base station at desired power levels.

29. The method of claim 28, further comprising:

operating the wireless communication system according to a Code Division Multiple Access mechanism.

30. The method of claim 28, wherein the system conditions include the power level and quality of the signal received by the base station from the subscriber unit.

31. The method of claim 28, wherein the system conditions include the type of service being provided to the subscriber unit.

32. The method of claim 28, wherein the system conditions include the mobility characteristics of the subscriber unit.

33. The method of claim 28, wherein communications received by the base station from the subscriber unit are over a high speed data link comprised of a plurality of reverse link code channels.

34. The method of claim 33, wherein the system conditions include the number of reverse link code channels comprising the high speed data link for communications received by the base station from the subscriber unit.

35. The method of claim 28, wherein the base station directs the subscriber unit to adjust the power control step size via a power control message.

36. The method of claim 28, further comprising:

the base station communicating with a plurality of subscriber units via respective forward and reverse links; and

the wireless communication system dynamically directing each subscriber unit to adjust its respective reverse link power level based upon system conditions.

37. The method of claim 35, further comprising:

the wireless communication system dynamically directing each subscriber unit to adjust its respective reverse link power level by individually determined power control step sizes based upon system conditions.

38. A base station that supports wireless communications with a subscriber unit, the base station comprising:

a subscriber unit interface that supports forward link transmissions to the subscriber unit and the receipt of reverse link transmissions from the subscriber unit;

a reverse link power control step size determination unit that, based upon power control step size capabilities of the subscriber unit and system conditions, determines a reverse link power control step size to be employed by the subscriber unit;

the base station directing the subscriber unit to increment or decrement the power of reverse link transmissions by the reverse link power control step size; and

based upon the power level of reverse link transmissions from the subscriber unit received by the base station, the base station periodically directing the subscriber unit to increment or decrement the power level of reverse link transmissions by the selected power control step size in an attempt to cause the reverse link transmissions to arrive at the base station at a desired power level.