Receiver performance in a communication network

Abstract

Methods and apparatus are described for improving receiver performance in a multicarrier communication network in which an encoded symbol is transmitted over a transmission channel in the communications system. A model of the transmission channel is estimated, said model characterising an effect of intercarrier interference on at least one carrier in the multicarrier system. The received symbol is decoded using the estimated model to remove a predicted effect of intercarrier interference. A pre-processor is also described for operation in conjunction with a communications receiver in the network. The pre-processor includes a channel estimator operable to estimate at least one feature of the communication channel based on a received signal. The pre-processor modifies the received signal dependent on the at least one estimated feature and provides the modified signal to the communications receiver.

1 . A communications system comprising:
 an input operable to receive an input signal that is transmitted via a communication channel, the input signal including first encoded data;   a channel estimator operable to produce a channel estimate for at least one feature of the communication channel based on the input signal and a feedback signal;   a signal combiner operable to combine the input signal and the channel estimate to result in an information bit sequence, the signal combiner including a forward error correction (FEC) unit for deriving:
 second encoded data, related to and different from the first encoded data, for inclusion in the feedback signal provided to the channel estimator; and 
 a decoded estimate of the second encoded data; 
   an output for providing the information bit sequence including the decoded estimate.   
     
     
         2 . The communications system according to  claim 1 , wherein the second encoded data is obtained by forward-error-correcting the first encoded data. 
     
     
         3 . The communications system according to  claim 2 , wherein the second encoded data is obtained by a forward-error-correcting the first encoded data using a Viterbi decoder. 
     
     
         4 . The communications system according to  claim 3 , wherein the Viterbi decoder is a dual-output Viterbi decoder. 
     
     
         5 . The communications system according to  claim 4 , wherein the dual-output Viterbi decoder includes a first output for providing the second encoded data. 
     
     
         6 . The communications system according to  claim 4  or  5 , wherein the dual-output Viterbi decoder includes a second output for providing the decoded estimate of the second encoded data. 
     
     
         7 . The communications system according to any one of  claims 2 - 6 , wherein said combiner is selected from the group consisting of:
 a maximum ratio combiner (MRC);   a zero forcing combiner; and   a minimum mean square error combiner.   
     
     
         8 . A method for a communications system comprising:
 receiving an input signal that is transmitted via a communication channel, the input signal including first encoded data;   producing a channel estimate for at least one feature of the communication channel based on the input signal and a feedback signal;   combining the input signal and the channel estimate to result in an information bit sequence, the signal combiner including a forward error correction (FEC) unit for deriving:
 second encoded data, related to and different from the first encoded data, for inclusion in the feedback signal provided to the channel estimator; and 
 a decoded estimate of the second encoded data; 
   providing the information bit sequence including the decoded estimate.