Iterative Message Passing for Pilot-Assisted Multiuser Detection in MC-CDMA Systems

Application of the belief propagation (BP) algorithm is proposed for pilot-assisted reception of multi-carrier code division multiple access systems where the input symbols are binary phase shift keying symbols. The proposed method utilizes a Bayesian network graph that includes channel parameters as explicit nodes representing random variables. Channel parameters in both frequency and time domains are included in the graph. The messages on the graph are obtained by making large system assumptions for the user symbols and Gaussian assumptions for the messages related to the channel parameters. Density evolution analysis is performed whose results match well with the simulation results. For the simulated scenario it is found that BP with the proposed graph outperforms channel estimation followed by graph based detection, and non-graph based iterative channel estimation.