Combining Coded Signals with Arbitrary Modulations in Orthogonal Relay Channels

摘要

We consider a relay channel for which the following assumptionsare made. (1) The source-destination and relay-destinationchannels are orthogonal (frequency division relay channel). (2) Therelay implements the decode-and-forward protocol. (3) The sourceand relay implement the same channel encoder, namely, a convolutionalencoder. (4) They can use arbitrary and possibly differentmodulations. In this framework, we derive the best combiner in thesense of the maximum likelihood (ML) at the destination and thebranch metrics of the trellis associated with its channel decoder forthe ML combiner and also for the maximum ratio combiner (MRC),cooperative-MRC (C-MRC), and the minimum mean-square error(MMSE) combiner.