Uniquely Decodable Codes with Fast Decoder for Overloaded Synchronous CDMA Systems

In this paper, we introduce a new class of signature matrices for overloaded synchronous CDMA systems that have a very low complexity decoder. While overloaded systems are more efficient from the bandwidth point of view, the Maximum Likelihood (ML) implementation for decoding is impractical even for moderate dimensions. Simulation results show that the performance of the proposed decoder is very close to that of the ML decoder. Indeed, the proposed decoding scheme needs neither multiplication nor addition and requires only a few comparisons . Furthermore, the computational complexity and the probability of error vs. Signal to Noise Ratios (SNR) are derived analytically.