Optimal use of request access TDMA slots for automatic level control

• US 7,065,378 B1
• Filed: 05/24/2004
• Issued: 06/20/2006
• Est. Priority Date: 07/06/1999
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Raleigh, Gregory G., Jones, Vincent K. IV, Raissinia, Ali, Pollack, Michael
• Primary Examiner(s): Nguyen, Lee
• Assistant Examiner(s): TRAN, TUAN A
• Application Number:
  US10/852,861
• Time in Patent Office: 757 Days
• Field of Search: 455 69- 70, 455/522, 455/434, 370203-210, 370318-319, 370280-282, 370/311, 370/343, 370334-335, 370/252, 370/314, 370336-337, 370/342, 370/344, 370/436, 370/437, 370/322, 370/465, 370/329, 370/348
• US Class Current: 455/522
• CPC Class Codes: H04W 52/223 predicting future states of the transmission
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands

Abstract

Systems and methods for controlling subscriber unit power level using power measurements made on access request transmissions. Since a subscriber unit access request typically precedes a subscriber unit data transmission by a relatively short period of time, the data transmission power level will then be based on a recent power measurement. The access request may also trigger a sequence of power control steps including the transmission of special upstream power measurement transmissions which can be used as the basis for even more accurate power control. These power control features are particularly useful in fading environments such as found in a wireless system.

Claims

1. In a point to multipoint communication system, apparatus for operating a central access point, said apparatus comprising:

means for receiving an access request transmission from a subscriber unit;

means for performing a power control sequence to control output power of said subscriber unit in response to said access request transmission, said power control sequence performing means comprises;

means for measuring power of said access request transmission;

means for formulating power adjustment information based on measured power of said access request transmission; and

means for, in response to measured power of said access request transmission, sending said power adjustment information to said subscriber unit to control power of a future transmission from said subscriber unit; and

wherein said access request transmission is included within an OFDM burst that includes access request information from said subscriber unit and another subscriber unit.

2. The apparatus of claim 1 further comprising:

means for, in response to said access request transmission, sending a grant message scheduling a time slot for said future transmission.

3. The apparatus of claim 2 wherein said future transmission comprises a data transmission.

4. The apparatus of claim 2 wherein said future transmission comprises a power measurement transmission that is part of said power control sequence and said grant message further schedules a time slot of a data transmission, said power control sequence performing means further comprising:

means for measuring power of said power measurement transmission; and

means for, in response to measured power of said access request transmission, sending a further power adjustment information to said subscriber unit to control power of a next transmission from said subscriber unit.

5. The apparatus of claim 4 wherein said future transmission is said data transmission.

6. The apparatus of claim 1 further comprising:

means for receiving network management transmissions from said subscriber unit at substantially fixed intervals;

means for measuring power of said network management transmissions as said network management transmissions are received; and

means for, in response to measured power of said network management transmissions, sending power adjustment information to said subscriber unit at intervals substantially similar to said fixed intervals.

7. The apparatus of claim 1 wherein said access request information from said subscriber unit is included only within a contiguous subband of said OFDM burst.

8. The apparatus of claim 7 further comprising:

means for measuring power of said subscriber unit by measuring power of at least one symbol inside said contiguous subband and at least one symbol outside said contiguous subband.

9. In a point to multipoint communication system, apparatus for operating a subscriber unit comprising:

means for sending an access request transmission to a central access point;

means for receiving a first power adjustment information indicator from said central access point, said first power adjustment information indicator having been generated based on measured power of said access request transmission;

means for receiving a scheduling transmission from said central access point, said scheduling transmission having been generated in response to said access request transmission, said scheduling transmission specifying a time slot of a future transmission by said subscriber unit; and

means for sending said future transmission to said central access point at a power level determined responsive to said first power adjustment information indicator; and

wherein said access request transmission is included within an OFDM burst that includes access request information from said subscriber unit and another subscriber unit.

10. The apparatus of claim 9 wherein said future transmission comprises a data transmission.

11. The apparatus of claim 9 wherein said future transmission comprises a power measurement transmission.

12. The apparatus of claim 11 wherein said scheduling transmission further specifies time of a data transmission.

13. The apparatus of claim 12 further comprising

means for receiving a second power adjustment information indicator from said central access point, said second power adjustment information indicator having been generated in response to said power measurement transmission;

and

means for sending said data transmission to said central access point at a power level determined responsive to said second power adjustment information indicator.

14. The apparatus of claim 9 further comprising:

means for sending network management transmissions to said central access point at substantially fixed intervals;

means for receiving power adjustment information indicators based on said network management transmissions;

from said central access point, said power adjustment information indicators being generated in response to power measurements made on said network management transmissions; and

means for adjusting power levels of said network management transmissions in response to said adjustment information indicators.

15. In a point to multipoint communication system, a product for operating a central access point, said product comprising:

instructions that cause receipt of an access request transmission from a subscriber unit;

instructions that cause performance of a power control sequence to control output power of said subscriber unit in response to said access request transmission, wherein said power control sequence comprises;

measuring power of said access request transmission;

formulating power adjustment information based on measured power of said access request transmission; and

in response to measured power of said access request transmission, sending said power adjustment information to said subscriber unit to control power of a future transmission from said subscriber unit;

a medium that stores the instructions; and

wherein said access request transmission is included within an OFDM burst that includes access request information from said subscriber unit and another subscriber unit.

16. In a point to multipoint communication system, a product for operating a subscriber unit, said product comprising:

instructions that cause sending of an access request transmission to a central access point;

instructions that cause receiving of a first power adjustment information indicator from said central access point, said first power adjustment information indicator having been generated based on measured power of said access request transmission;

instructions that cause receiving of a scheduling transmission from said central access point, said scheduling transmission having been generated in response to said access request transmission, said scheduling transmission specifying a time slot of a future transmission by said subscriber unit;

instructions that cause sending of said future transmission to said central access point at a power level determined responsive to said first power adjustment information indicator; and

a medium that stores the instructions; and

wherein said access request transmission is included within an OFDM burst that includes access request information from said subscriber unit and another subscriber unit.

17. A method for operating a node in a communication system, said method comprising:

receiving OFDM signals from a subscriber unit;

from said OFDM signals, extracting an access request transmission and a data transmission, wherein said access request transmission is included within an OFDM burst;

based on received power levels of said access request transmission and said data transmission, formulating power adjustment information; and

transmitting said power adjustment information to said subscriber unit;

wherein said OFDM burst includes access request information from said subscriber unit and another subscriber unit.

18. The method of claim 17 further comprising:

extracting a power measurement transmission from said OFDM signals; and

wherein said power adjustment information is formulated further based on received power levels of said power measurement transmission.

19. Apparatus for operating a node in a communication system, said apparatus comprising:

a physical layer block that receives OFDM signals from a subscriber unit and extracts an access request transmission and a data transmission from said OFDM signals, wherein said access request transmission is included within an OFDM burst; and

a physical layer control processor that, based on received power levels of said access request transmission and said data transmission, formulates power adjustment information; and

said physical layer block being used to transmit said power adjustment information to said subscriber unit;

wherein said OFDM burst includes access request information from said subscriber unit and another subscriber unit.

20. The apparatus of claim 19 wherein said physical layer block further extracts a power measurement transmission from said OFDM signals and said power adjustment information is formulated based on said power measurement transmission.

21. Apparatus for operating a node in a communication system, said apparatus comprising:

means for receiving OFDM signals from a subscriber unit;

means for, from said OFDM signals, extracting an access request transmission and a data transmission, wherein said access request transmission is included within an OFDM burst;

means for, based on received power levels of said access request transmission and said data transmission, formulating power adjustment information; and

means for transmitting said power adjustment information to said subscriber unit;

wherein said OFDM burst includes access request information from said subscriber unit and another subscriber unit.