1. A method for detecting low density signature (LDS) transmissions, the method comprising: calculating, at a detector, a plurality of function nodes (FNs) according to a plurality of received multiplexing signals for a one or a plurality of user equipments (UEs) using a plurality of first message passing algorithm (MPA) computations that map a plurality of variable nodes (VNs) corresponding to the UEs to the FNs and using a priori information in an initial vector of probabilities for each of the VNs; excluding from the first MPA computations a plurality of first relatively small multiplication terms; updating the probabilities for the VNs using the last calculated FNs and a plurality of second MPA computations that map the FNs to the VNs; and excluding a plurality of second relatively small multiplication terms from the second MPA calculations.