One or more codewords are generated by encoding input bits at input bit positions onto sub-channels that are provided by a code. Each of the sub-channels has an associated reliability of correct decoding of an input bit at an input bit position. Each codeword is transmitted to a decoder, and a word based on each transmitted codeword is received at the decoder. Each received word is decoded, and the reliabilities of the sub-channels are determined based on decoded bits and known input bits from which each codeword was generated. An indication that is based on the determined reliabilities of the sub-channels, such as an indication of the determined reliabilities, is transmitted to the encoder, and may be used by the encoder in selecting the sub-channels for encoding subsequent input bits, for example.