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

• US 6,956,840 B1
• Filed: 09/21/1998
• Issued: 10/18/2005
• Est. Priority Date: 09/21/1998
• Status: Expired due to Fees

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Inventors: Proctor, James A. Jr.
• Primary Examiner(s): Rao, Seema S.
• Assistant Examiner(s): Harper, Kevin C.
• Application Number:
  US09/158,421
• Time in Patent Office: 2,584 Days
• Field of Search: 370/329, 370/335, 370/342, 370/441, 370/468, 370/479, 370/311, 370/465, 455/436, 455/450, 455/522, 455/69
• US Class Current: 370/342
• 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 Code Division Multiple Access (CDMA) type wireless system 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 wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the method comprising the steps of:

a) making available a plurality of subchannels within each CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

b) allocating available subchannels only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

c) on a reverse link, providing a standby mode connection for subscriber units which are powered on, but not presently having traffic channels allocated, the standby mode connection sending a heartbeat signal from the subscriber unit to the base station, the heartbeat signal being sent from the subscriber unit to the base station at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link; and

d) during the standby mode, sending a link quality report message to the subscriber unit in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.

3. A method as in claim 1 or 2 wherein a plurality of subchannels are made available on a single radio frequency carrier by assigning different codes for each subchannel.

4. A method as in claim 1 or 2 wherein the link quality report message is sent on a pilot channel.

5. A method as in claim 1 or 2 wherein the link quality report message is sent on a sync channel.

6. A method as in claim 1 or 2 wherein the link quality report contains a data value indicating an amount by which the subscriber unit should change its transmit power level for the corresponding subchannel.

7. A method as in claim 1 or 2 wherein the link quality report contains a data value indicating a bit error rate.

8. A method as in claim 1 or 2 wherein the link quality report contains a value indicating noise energy.

9. A method as in claim 1 or 2 additionally comprising the step of:

calculating a subscriber unit transmit power level using a data value indicated by the link quality report.

10. A method as in claim 1 or 2 wherein the link quality report message is sent on a paging channel.

2. A method for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the method comprising the steps of:

a) making available a plurality of subchannels within each CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

b) allocating available subchannels only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

c) on a reverse link, providing a standby mode connection for subscriber units which are powered on, but not presently actively sending data, the standby mode connection sending a heartbeat signal from the subscriber unit to the base station, the heartbeat signal being sent from the subscriber unit to the base station at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link, the heartbeat signal being time slotted between inactive subchannels; and

d) during the standby mode, sending a link quality report message to the subscriber unit in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.

11. A system for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the system having a base station comprising:

a radio transceiver making available a plurality of subchannels within each CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

a bandwidth manager allocating available subchannels only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

the bandwidth manager providing a standby mode connection on a reverse link for subscriber units which are powered on, but not presently having traffic channels allocated;

the radio transceiver receiving a heartbeat signal over the standby mode connection from a subscriber unit at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link; and

the radio transceiver sending a link quality report message to the subscriber unit during the standby mode in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.

13. A system as in claim 11 or 12 wherein the radio transceiver provides a plurality of subchannels on a single radio frequency carrier by assigning different codes for each subchannel.

14. A system as in claim 11 or 12 wherein the link quality report message is sent on a pilot channel.

15. A system as in claim 11 or 12 wherein the link quality report message is sent on a sync channel.

16. A system as in claim 11 or 12 wherein the link quality report contains a data value indicating an amount by which the subscriber unit should change its transmit power level for the corresponding subchannel.

17. A system as in claim 11 or 12 wherein the link quality report contains a data value indicating a bit error rate.

18. A system as in claim 11 or 12 wherein the link quality report contains a value indicating noise energy.

19. A system as in claim 11 or 12 wherein the link quality report message is sent on a paging channel.

12. A system for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the system having a base station comprising:

a radio transceiver making available a plurality of subchannels within each CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

a bandwidth manager allocating available subchannels only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

the bandwidth manager providing a standby mode connection on a reverse link for subscriber units which are powered on, but not presently actively sending data;

the radio transceiver receiving a heartbeat signal over the standby mode connection from a subscriber unit at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link, the heartbeat signal being time slotted between inactive subchannels; and

the radio transceiver sending a link quality report message to the subscriber unit during the standby mode in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.

20. A system for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the system having a base station comprising:

transceiver means for making available a plurality of subchannels within each CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

bandwidth management means for allocating available subchannels only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

the bandwidth management means providing a standby mode connection on a reverse link for subscriber units which are powered on, but not presently having traffic channels allocated;

the transceiver means receiving a heartbeat signal over the standby mode connection from a subscriber unit at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link; and

the transceiver means sending a link quality report message to the subscriber unit during the standby mode in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.

21. A system for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the system having a subscriber unit comprising:

a radio transceiver tuning to at least one subchannel of a plurality of subchannels within a CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

a bandwidth manager allocating the at least one subchannel only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

the bandwidth manager opening a standby mode connection on a reverse link during a standby mode, the bandwidth manager not presently having traffic channels allocated;

the radio transceiver sending a heartbeat signal over the standby mode connection to a base station at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link; and

the radio transceiver receiving a link quality report message from the base station during the standby mode in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.

23. A system as in claim 21 or 22 wherein the link quality report message is received on a pilot channel.

24. A system as in claim 21 or 22 wherein the link quality report message is received on a sync channel.

25. A system as in claim 21 or 22 wherein the link quality report contains a data value indicating an amount by which the subscriber unit should change its transmit power level for the corresponding subchannel.

26. A system as in claim 21 or 22 wherein the link quality report contains a data value indicating a bit error rate.

27. A system as in claim 21 or 22 wherein the link quality report contains a value indicating noise energy.

28. A system as in claim 21 or 22 wherein a subscriber unit transmit power level is calculated using a data value indicated by the link quality report.

29. A system as in claim 21 or 22 wherein the link quality report message is received on a paging channel.

22. A system for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the system having a subscriber unit comprising:

a radio transceiver tuning to at least one subchannel of a plurality of subchannels within a CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

a bandwidth manager allocating the at least one subchannel only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

the bandwidth manager opening a standby mode connection on a reverse link during a standby mode, the bandwidth manager not presently having traffic channels allocated;

the radio transceiver sending a heartbeat signal over the standby mode connection to a base station at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link, the heartbeat signal being time slotted between inactive subchannels; and

the radio transceiver receiving a link quality report message from the base station during the standby mode in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.

30. A system for providing wireless communication of digital signals, the digital signals being communicated between a plurality of wireless subscriber units and a base station, the digital signals being communicated using at least one radio frequency channel via Code Division Multiple Access (CDMA) modulated radio signals, the digital signals also having a given nominal data rate, the system having a subscriber unit comprising:

transceiver means for tuning to at least one subchannel of a plurality of subchannels within a CDMA radio channel, wherein a data rate of each subchannel is much less than the nominal data rate of the digital signals;

bandwidth management means for allocating the at least one subchannel only on an as-needed basis, with the number of subchannels allocated thereby changing during the duration of a given session;

the bandwidth management means opening a standby mode connection on a reverse link during a standby mode, the bandwidth manager not presently having traffic channels allocated;

the transceiver means sending a heartbeat signal over the standby mode connection to a base station at a data rate which is sufficiently fast enough to maintain bit synchronization on the reverse link; and

the transceiver means receiving a link quality report message from the base station during the standby mode in response to the heartbeat signal, the link quality report message containing a link quality report that is used to control the transmit power level of the subscriber unit.