Method and system for evaluating a wireless link

• US 7,649,868 B2
• Filed: 12/30/2004
• Issued: 01/19/2010
• Est. Priority Date: 12/22/2000
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Tellado, Jose, Heath, Robert W.
• Primary Examiner(s): Moe; Aung S
• Assistant Examiner(s): Riyami; Abdullah
• Application Number:
  US11/027,031
• Publication Number:
  US 20050117543A1
• Time in Patent Office: 1,846 Days
• Field of Search: 370/328, 370/329, 370/332, 370/341, 370/334, 370/339, 370/252, 370/389, 370/282, 370/352, 370/400, 370/465, 370/208, 370/432, 370/436, 370/312, 455/67.11, 455/67.13, 455/135, 455/101, 455/132, 455/272, 455/552, 455/446, 455/69, 455/62, 375/225, 375/220, 375/221, 375/227, 375/254, 375/259, 375/285, 375/295, 375/377, 714/708, 714/709
• US Class Current: 370/332
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication

Abstract

A wireless link between a first transmitter and a first receiver in a multiple access communications system is evaluated by receiving, at the first transmitter, information that is intended for a second receiver and that is transmitted in a second transmission mode that is different from the current transmission mode and obtaining an error measure for the information that is received at the first receiver and intended for the second receiver. The obtained error measure is then used to determine if the second transmission mode is an acceptable transmission mode. In an embodiment, if the second transmission mode is determined to be acceptable, then the current transmission mode of the first receiver can be replaced by the second transmission mode. In an embodiment, the current transmission mode is replaced by the second transmission mode only if the second transmission mode is a “higher” transmission mode than the current transmission.

Claims

1. An apparatus for evaluating a wireless link between a transmitter and a first receiver in a multiple access wireless communications system, wherein said transmitter is transmitting information intended for a first receiver in a first transmission mode and information intended for a second receiver in a second transmission mode that is different from said first transmission mode, the apparatus comprising:

means for receiving information that is intended for the second receiver and that is transmitted in said second transmission mode;

means for obtaining, at said first receiver, an error measure for said information that is received at said first receiver and intended for said second receiver;

means for determining if said second transmission mode is an acceptable transmission mode at least in part based on said error measure obtained for said information that is received at said first receiver and intended for said second receiver; and

means for determining if said second transmission mode should be used for subsequent transmissions of information frames that is intended for said first receiver only if said second transmission mode is determined to be acceptable, said means for determining if said second transmission mode should be used for subsequent frame transmissions comprising;

means for determining if said second transmission mode is higher than a current transmission mode that is used to transmit information intended for said first receiver;

means for using said second transmission mode for subsequent transmissions, from said transmitter, of information intended for said first receiver if said second transmission mode is determined to be higher than said current transmission mode; and

means for continuing to use said current transmission mode for subsequent transmissions, from said transmitter, of information intended for said first receiver if said second transmission mode is determined to be lower than said current transmission mode.

2. An apparatus as claimed in claim 1, wherein said means for determining if said second transmission mode should be used for subsequent transmissions of information comprises means for comparing a characteristic of said second transmission mode to said first transmission mode.

3. An apparatus as claimed in claim 1, further comprising:

means for indicating to said transmitter that said second transmission mode should be used for subsequent transmissions of frames intended for said first receiver.

4. An apparatus as claimed in claim 3, further comprising:

means for indicating to multiple transmitters that said selected transmission mode should be used for subsequent transmissions of frames intended for said first receiver.

5. An apparatus as claimed in claim 3, further comprising:

means for transmitting subsequent frames to said receiver in said second transmission mode.

6. An apparatus as claimed in claim 1, wherein said means for determining if said second transmission mode is acceptable comprises means for determining if said obtained error measure is above or below an error threshold.

7. An apparatus as claimed in claim 1, further comprising:

means for adding said second transmission mode to a database of acceptable transmission modes if said obtained error measure for said information transmitted in said second transmission mode is below an error threshold.

8. An apparatus as claimed in claim 7, further comprising:

means for selecting a lower transmission mode for information intended for said first receiver from acceptable modes identified in said database.

9. An apparatus as claimed in claim 7, further comprising:

means for ranking transmission modes that are added to said database of acceptable transmission modes.

10. An apparatus as claimed in claim 9, further comprising:

means for selecting a new transmission mode for information intended for said first receiver at least in part based on said transmission mode rankings.

11. An apparatus as claimed in claim 10, further comprising:

means for accumulating error statistics for transmission modes that are added to said database of acceptable transmission modes.

12. An apparatus as claimed in claim 11, further comprising:

means for selecting a new transmission mode for information intended for said first receiver at least in part based on said accumulated error statistics.

13. An apparatus as claimed in claim 7, further comprising:

means for replacing a current transmission mode with the next higher acceptable transmission mode that is stored in said database of acceptable modes.

14. An apparatus as claimed in claim 1, further comprising:

means for projecting an acceptability of other transmission modes that may be used to transmit information intended for said first receiver based at least in part on said mode acceptability determination of said information that is intended for said second receiver and transmitted in said second transmission mode.

15. An apparatus as claimed in claim 1, further comprising:

means for ensuring that said first transmission mode used by said transmitter to transmit information intended for said first receiver is no higher than said second transmission mode if said second transmission mode is not acceptable; and

means for ensuring that said first transmission mode used by said transmitter to transmit information intended for said first receiver is at least as high as said second transmission mode if said second transmission mode is acceptable.

16. An apparatus as claimed in claim 1, further comprising:

means for decoding said information intended for said second receiver into decoded information before said error measure is obtained, said error measure being related to said decoded information.

17. An apparatus as claimed in claim 16, wherein means for obtaining said error measure comprises means for utilizing information selected from the group comprising the metric of a winning path in a Virterbi decoder, the output bit/symbol/packet likelihood, a cyclic redundancy check code, a parity check code, a Reed-Solomon code, a BCH code, a Hamming code, a cyclic code, an arithmetic code, or a Golay code, or combinations thereof.

18. An apparatus as claimed in claim 1, wherein said error measure for said information is obtained prior to decoding.

19. An apparatus as claimed in claim 18, wherein said means for obtaining an error measure comprises means for utilizing information selected from the group comprising the means square error of equalizer, a measure of equalizer convergence, or post-processing signal to noise plus interference ratio, or combinations thereof.

20. An apparatus as claimed in claim 1, wherein said transmitter transmits said information from multiple antennas.

21. An apparatus as claimed in claim 1, wherein said multiple access wireless communications system utilizes a multiple access protocol that is selected from at least one of a group of multiple access protocols comprising:

time-division multiple access (TDMA), frequency-division multiple access (FDMA), code-division multiple access (CDMA), space-division multiple access (SDMA), orthogonal frequency division multiple access (OFDMA), wavelength division multiple access (WDMA), wavelet division multiple access, orthogonal division multiple access (ODMA), quasi-ODMA, packet reservation multiple access (PRMA), or carrier sense multiple access (CSMA), or combinations thereof.