Channel quality estimation from raw bit error rate

Abstract

Channel quality metrics (such as SINR, BLER, and the like) are derived from a raw bit error rate (RBER), defined as the error rate of raw bits output by a demodulator. These initial raw bits are decoded and error-checked (or error-corrected). The error-free decoded bits are re-encoded, and the regenerated raw bits are compared to the initial raw bits to determine the RBER. The RBER is then converted to SINR, BLER, or other channel quality metric. The RBER-based metrics are derived from a data channel rather than reference signals, and hence more accurately reflect deviations from nominal transmission power level, and include receiver demodulator impairments.

What is claimed is: 
     
         1 . A method of estimating channel quality in receiver operative in a wireless communication network, comprising:
 receiving a wireless signal from a transmitter;   demodulating the received signal to generate initial raw bits;   decoding the initial raw bits to generate decoded bits;   performing an error check on the decoded bits;   generating regenerated raw bits by encoding the decoded bits that pass the error check;   comparing the initial raw bits to the regenerated raw bits to determine a raw bit error rate (RBER); and   using the RBER to generate a channel quality metric.   
     
     
         2 . The method of  claim 1  further comprising:
 storing the initial raw bits; 
 transmitting a retransmission request; 
 receiving a retransmitted signal; 
 demodulating the retransmitted signal to generate retransmitted raw bits; 
 decoding the retransmitted raw bits to generate retransmitted decoded bits; 
 performing an error check on the retransmitted decoded bits; 
 generating regenerated retransmitted raw bits by encoding the retransmitted decoded bits that pass the error check; 
 comparing the initial raw bits and the retransmitted raw bits to the regenerated retransmitted raw bits to determine a raw bit error rate (RBER) over both the received signal and retransmitted signal transmission durations. 
 
     
     
         3 . The method of  claim 1  further comprising using the channel quality metric from a current transmission duration and at least one prior transmission duration to jointly predict the channel quality metric for a future transmission duration having the same frequency allocation. 
     
     
         4 . The method of  claim 1  wherein the received wireless signal was generated using a high order modulation and heavy encoding to increase the number of raw bit errors. 
     
     
         5 . The method of  claim 4  wherein high order modulation comprises 16-QAM or 64-QAM. 
     
     
         6 . The method of  claim 4  wherein heavy encoding comprises the use of repetition code to extend the coding rate to below rate 1/3. 
     
     
         7 . The method of  claim 1  further comprising terminating the method when the relative speed between the transmitter and receiver exceeds a predetermined threshold. 
     
     
         8 . The method of  claim 1  further comprising terminating the method if the number of initial raw bits in error over a predetermined duration is below a predetermined threshold. 
     
     
         9 . The method of  claim 1  wherein using the RBER to generate a channel quality metric comprises converting the RBER to a RBER-based signal to interference and noise ratio (SINR). 
     
     
         10 . The method of  claim 9  wherein converting the RBER to a RBER-based SINR comprises indexing a mapping table using the RBER and obtaining a corresponding RBER-based SINR. 
     
     
         11 . The method of  claim 10  wherein indexing a mapping table comprising indexing a mapping table corresponding to the modulation format under which the received signal was transmitted. 
     
     
         12 . The method of  claim 1  wherein using the RBER to generate a channel quality metric comprises converting the RBER to a RBER-based block error rate (BLER). 
     
     
         13 . A method of estimating channel quality in receiver operative in a wireless communication network, comprising:
 receiving a wireless information-bearing signal from a transmitter, the received signal modulated using one of 16-QAM or 64-QAM modulation and encoded using a repetition code to extend the coding rate to below rate 1/3;   demodulating the received signal to generate initial raw bits;   decoding the initial raw bits to generate decoded bits;   performing an error check on the decoded bits;   generating regenerated raw bits by encoding the decoded bits that pass the error check;   comparing the initial raw bits to the regenerated raw bits to determine a raw bit error rate (RBER); and   using the RBER to generate a channel quality metric.   
     
     
         14 . A receiver operative in a wireless communication network, comprising:
 a demodulator operative to demodulate a received wireless communication signal to generate initial raw bits;   a decoder operative to decode the initial raw bits to generate decoded bits;   an error checker operative to detect or correct errors in the decoded bits;   an encoder operative to encode error-free decoded bits to generate regenerated raw bits;   a comparator operative to compare the initial raw bits to the regenerated raw bits and determine a raw bit error rate (RBER); and   a converter operative to convert the RBER to a channel quality metric.   
     
     
         15 . The receiver of  claim 14  further comprising memory operative to store an RBER value calculated over a first transmission duration. 
     
     
         16 . The receiver of  claim 14  further comprising memory operative to store initial raw bits from a signal for which the receiver requests retransmission. 
     
     
         17 . The receiver of  claim 14  wherein the comparator includes a bit selector operative to select only a high error probability subset of initial and regenerated raw bits per symbol for comparison.