Predicting link quality of a link

• US 7,719,999 B2
• Filed: 09/04/2008
• Issued: 05/18/2010
• Est. Priority Date: 03/13/2006
• Status: Active Grant

• Current Assignee: Novanta Inc.
• Original Assignee: NDSSI Holdings LLC (Novanta Inc.)
• Inventors: Karnam, Mohan Ramasudha, Chari, Sujai, Fu, Dengwei
• Primary Examiner(s): Yao; Kwang B
• Assistant Examiner(s): Cehic; Kenan
• Application Number:
  US12/231,564
• Publication Number:
  US 20090003234A1
• Time in Patent Office: 621 Days
• Field of Search: 370/332, 370/333, 370/241, 370/252, 370/253, 370/343, 370/216, 370/242, 370/254, 370/310, 370/344, 370/478, 370/480, 370/485, 375/295, 375/260, 375/224, 375/227, 375/228, 455/423, 455/24, 455/67.11, 455/67.13, 455/114.2, 455/115.1, 455/115.3, 4552261-2263, 714/48, 714/699, 714/704, 714/712, 714/746, 714/701, 714/761, 714/762, 714/799, 714/811, 714/817
• 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

Abstract

A method and apparatus of predicting link quality of a link are disclosed. One exemplary method includes a receiver receiving multi-carrier modulated signals over a period of time. A signal to noise ratio (SNR) for each received sub-carrier is estimated. An ordered sequence of the signal to noise ratios (SNR)s are constructed based on interleaving of the multi-carrier modulated signals, wherein an order of the interleaving is used to set the ordered sequence of the signal to noise ratios (SNR)s. The receiver estimates link packet error rate (PER) based upon knowledge of encoding of the multi-carrier modulated signals used during transmission and the ordered sequence.

Claims

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

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

estimating a signal to noise ratio (SNR) for each received sub-carrier;

constructing an ordered sequence of the signal to noise ratios (SNR)s based on interleaving of the multi-carrier modulated signals, wherein an order of the interleaving is used to set the ordered sequence of the signal to noise ratios (SNR)s;

the receiver estimating link packet error rate (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 signal to noise ratios (SNR)s based upon knowledge of transmission interleaving.

3. The method of claim 1, wherein estimating signal to noise ratio (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 orthogonal frequency division multiplexed (OFDM) signals.

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

6. The method of claim 5, further comprising:

estimating link packet error rate (PER) of packets over time, and maintaining a running average of estimated link packet error rate (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 packet error rate (PER) link estimate is made at a receiver of the multi-carrier modulated signals.

9. The method of claim 1, wherein the packet error rate (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 low density parity check (LDPC) coding.

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

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

estimating a signal to noise ratio (SNR) for each received sub-carrier;

constructing an ordered sequence of the signal to noise ratios (SNR)s based on interleaving of the multi-carrier modulated signals, wherein an order of the interleaving is used to set the ordered sequence of the signal to noise ratios (SNR)s;

the receiver estimating link packet error rate (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 packet error rate (PER) estimates.

16. The method of claim 15, wherein the transmission mode that is selected is the mode that corresponds with the best packet error rate (PER) estimate.

17. The method of claim 15, wherein the transmission 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 signal to noise ratio (SNR) for each received sub-carrier;

means for constructing an ordered sequence of the signal to noise ratios (SNR)s based on interleaving of the multi-carrier modulated signals, wherein an order of the interleaving is used to set the ordered sequence of the signal to noise ratios (SNR)s;

means for estimating link packet error rate (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 packet error rate (PER) back to a transmitter.

20. The receiver of claim 18, further comprising de-interleaving the sequence of signal to noise ratios (SNR)s based upon knowledge of transmission interleaving.