Joint Data Detection and Channel Estimation, Preferably of DS/CDMA Signals

In this page we present two efficient iterative structures of tractable complexity for joint mutliuser detection and multichannel estimation (JDE) of DS/CDMA signals. The schemes results form an application of the EM and the SAGE algorithm respectively. The EM-JDE receiver updates the data bit sequences in parallel while the SAGE-JDE receiver reestimates them successively. The channel parameters are updated in parallel in both schemes. The EM algorithm provides a set of free parameters, called weight coefficients, which can be selected to optimize its performance. Two optimality criteria are defined and analytical expressions for the corresponding optimized weight coefficients are given. Monte Carlo simulations of a synchronous scenario show that the proposed JDE receivers are near-far resistant and robust against errors in the estimation of the channel parameters. Moreover, very short training sequences are required for the JDE schemes to converge with. Simulations results further demonstrate that the SAGE-JDE receiver exhibits a better performance when the user's bit sequences are updated in the order of increasing signal strength, i.e. the bit sequence of the user with the weakest signal strength is updated first at each stage.