Link quality prediction

• US 20090003234A1
• Filed: 09/04/2008
• Published: 01/01/2009
• Est. Priority Date: 03/13/2006
• Status: Active Grant

• Current Assignee: Novanta Inc.
• Original Assignee: TZero Technologies Incorporated (Novanta Inc.)
• Inventors: Chari, Sujai, Fu, Dengwei, Karnam, Mohan Ramasudha
• Granted Patent: US 7,719,999 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 1/71637 Receiver aspects H04B1/7183 takes precedence
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/203 Details of error rate determination, e.g. BER, FER or WER
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Claims

1. A method of predicting link quality of a link, comprising:

receiving multi-carrier modulated signals over a period of time;

estimating an SNR for each received sub-carrier;

constructing an ordered sequence of the SNRs based on interleaving of the multi-carrier modulated signals;

estimating link PER based upon knowledge of encoding of the multi-carrier modulated signals used during transmission and the ordered sequence.

2. The method of claim 1, further comprising de-interleaving the ordered sequence of SNRs based upon knowledge of transmission interleaving.

3. The method of claim 1, wherein estimating SNR for each received sub-carrier is based upon a transmission channel, noise variance and interference.

4. The method of claim 1, wherein the multi-carrier modulated signals are OFDM signals.

5. The method of claim 1, wherein estimating link PER is performed per packet.

6. The method of claim 5, further comprising:

estimating link PER of packets over time, and maintaining a running average of estimated link PER.

7. The method of claim 6, wherein length of the running average is based upon how rapidly transmission channels are varying.

8. The method of claim 1, wherein the PER link estimate is made at a receiver of the multi-carrier modulated signals.

9. The method of claim 1, wherein the PER link estimate is made at a transmitter of the multi-carrier modulated signals based on feedback from a receiver of the multi-carrier modulated signals.

10. The method of claim 8, wherein at least one of the receiver and a transmitter comprises multiple receive antennas.

11. The method of claim 10, wherein the receiver comprises maximal ratio combining.

12. The method of claim 10, wherein the receiver comprises phase combining.

13. The method of claim 10, wherein the receiver comprises receive antenna select diversity.

14. The method of claim 1, wherein the encoding comprises forward error correction (FEC) coding comprising at least one of convolutional, turbo and LDPC coding.

15. A method of selecting a transmission mode of a transmission link based on a predicted link quality of the link, comprising:

receiving multi-carrier modulated signals over a period of time;

estimating an SNR for each received sub-carrier;

constructing an ordered sequence of the SNRs based on interleaving of the multi-carrier modulated signals;

estimating link PER for all possible transmission modes based upon knowledge of encoding of the multi-carrier modulated signals used during transmission and the ordered sequence;

selecting a transmission mode based upon the link PER estimates.

16. The method of claim 15, wherein the mode that is selected is the mode that corresponds with the best PER estimate.

17. The method of claim 15, wherein the modes comprise at least one of multiple data transmission rates, multiple codes, multiple transmit antennas and multiple receive antennas.

18. A receiver comprising:

means for receiving multi-carrier modulated signals over a period of time;

means for estimating an SNR for each received sub-carrier;

means for constructing an ordered sequence of the SNRs based on interleaving of the multi-carrier modulated signals;

means for estimating link PER based upon knowledge of encoding used during transmission, and the sequence.

19. The receiver of claim 18, wherein the receiver feeds the estimated link PER back to a transmitter.

20. The receiver of claim 18, further comprising de-interleaving the sequence of SNRs based upon knowledge of transmission interleaving.