Patent ID: 8170155

Claim:
A channel quality measurement apparatus adapted to measure a quality of a channel over which has been transmitted a sequence of symbols produced by encoding and constellation mapping a source data element sequence, the apparatus comprising: a symbol de-mapper, receiving as input a sequence of received symbols over the channel whose quality is to be measured, the symbol de-mapper being adapted to perform symbol de-mapping on the sequence of received symbols to produce a sequence of soft data element decisions, a type of the symbol de-mapping being based on a first channel quality indicator previously transmitted by the apparatus to a transmitter of the sequence of symbols; a soft decoder, receiving as input the sequence of soft data element decisions produced by the symbol de-mapper, the soft decoder being adapted to decode the sequence of soft data element decisions to produce a decoded output sequence; an encoder, receiving as input the decoded output sequence produced by the soft decoder, the encoder being adapted to re-encode the decoded output sequence with an identical code to a code used in encoding the source data element sequence to produce a re-encoded output sequence; and a correlator, receiving as input the sequence of soft data element decisions produced by said de-mapper, and the re-encoded output sequence produced by the encoder, said correlator being adapted to produce a second channel quality indicator by determining a correlation between the sequence of soft data element decisions and the re-encoded output sequence, wherein the apparatus is adapted to feed the second channel quality indicator back to the transmitter to apply a type of mapping of the source data element sequence based on the second channel quality indicator so that the type of mapping applied at the transmitter is based on the correlation between the sequence of soft data element decisions and the re-encoded output sequence.