Performance analysis of Osman Nuri Ucan (ONU)-receiver for trellis coded M-QAM schemes in partial response channels

Trellis coded M-QAM modulated signals are analysed in a partial response channel using the Osman Nuri Ucan (ONU)-receiver proposed by Ucan in 1992. The ONU-receiver is composed of k-parallel unit memory decoder, k/k+1 rated systematic encoder, cascaded with a PRS channel model. The combined trellis structure of ONU-receiver reduces the state number from 2^k2^ν2^k+1 resulting from k-unit memory of the parallel precoders, ν unit memory of the systematic encoder and (k+1) unit memory of the PRS channel model to only 2^k+ν. Therefore considering the PRS channel together with classical trellis coded M-QAM structures does not increase the state number and decoding complexity. The ONU receiver improves both the bandwidth efficiency and error performance with no resulting increase in the decoding complexity. As an example, the error event lower bound of the ONU-receiver is derived for 4QAM-TCM having an encoder memory ν=1 and ν=2 in AWGN and colored noise environments