Date Added: Nov 2012
Analog Network Coding (ANC) has been widely used in wireless uplink to improve throughput and provide spatial diversity. However, the receiver has to estimate the channel coefficients of all users to perform coherent detection, thus the signaling overhead is sometimes formidable and may even outweigh the performance gain. To reduce the channel estimation overhead, the authors study non-coherent modulations in this paper with emphasis on receiver design and performance analysis. Depending on channel state information, they first develop the coherent, partial coherent and non-coherent receivers based on Maximum Likelihood (ML) principle. As the ML non-coherent receiver has a non-tractable integral form, they further propose two sub-optimum receivers depending on the relative quality of source-relay channel and relay-destination channel.