Link quality prediction
View Patent ↗A method and apparatus of predicting link quality of a link is disclosed. The method includes receiving multi-carrier modulated signals over a period of time, estimating an SNR for each received sub-carrier, constructing a sequence of the SNRs, and estimating link PER based upon knowledge of encoding and/or interleaving used during transmission, and the sequence of SNRs.
1. A method of predicting link quality of a link, comprising:
receiving multi-carrier modulated signals over a period of time;
estimating an signal to noise ratio (SNR) for each received sub-carrier;
constructing a sequence of the SNRs;
estimating link packet error rate (PER) based upon knowledge of encoding used during transmission and the sequence;
wherein estimating link PER based upon knowledge of encoding used during transmission, and the sequence comprises:
convolving the sequence with codewords, wherein the codewords are constructed based upon knowledge of the encoding at a transmitter;
generating a sequence of probability of error values by mapping each output of the convolution;
estimating link PER by summing the probability of error values.
2. The method of claim 1 , further comprising de-interleaving the 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 the 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 the 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. The method of claim 1 wherein convolving the sequence with codewords comprises convolving the sequence with each codeword of a library of codewords.
16. The method of claim 1 wherein estimating PER further comprises scaling the estimate by a ratio of packet length to interleaver length.
17. A method of predicting link quality of a link, comprising:
receiving multi-carrier modulated signals over a period of time;
estimating an signal to noise ratio (SNR) for each received sub-carrier;
constructing a sequence of the SNRs;
estimating link packet error rate (PER) based upon knowledge of encoding used during transmission and the sequence;
wherein estimating link PER based upon knowledge of encoding used during transmission and the sequence comprises;
convolving the sequence with each codeword of a library of codewords, wherein the codewords are constructed based upon knowledge of the encoding at a transmitter;
generating a sequence of probability of error values by mapping each output of the convolution;
estimating link PER by summing the probability of error values.
18. 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 signal to noise ratio (SNR) for each received sub-carrier;
constructing sequence of the SNRs;
estimating link packet error rate (PER) for all possible transmission modes based upon knowledge of encoding used during transmission and the sequence;
selecting a transmission mode based upon the link PER estimates;
wherein estimating link PER based upon knowledge of encoding used during transmission, and the sequence comprises;
convolving the sequence with codewords, wherein the codewords are constructed based upon knowledge of the encoding at a transmitter;
generating a sequence of probability of error values by mapping each output of the convolution;
estimating link PER by summing the probability of error values.
19. The method of claim 18 , wherein the mode that is selected is the mode that corresponds with the best PER estimate.
20. The method of claim 18 , wherein the modes comprise at least one of multiple data transmission rates, multiple codes, multiple transmit antennas and multiple receive antennas.