Low-Rank Matrix Factorization Based OFDM-DCSK Receiver With Enhanced BER Performance for Uplink Multiuser Transmission

In traditional multi-user orthogonal frequency division multiplexing differential chaos shift keying (MU-OFDM-DCSK) systems, the noisy correlation of reference signals with overlapped information-bearing signals from multiple users degrades the bit error rate (BER). This paper devises a MU-OFDM-DCSK receiver that enhances the BER performance for uplink transmission. In our design, the challenges of reducing multi-user interferences (MUIs) and noise in both reference and information-bearing chaotic signals are addressed via leveraging the low-rank structure of the received signal matrix. By exploiting low-rank matrix factorization, a novel objective function is constructed. Minimization of this function, which corresponds to a least squares optimization, can effectively decode the transmitted data bits, even in the presence of additive white Gaussian noise (AWGN) and MUIs. The BER of our scheme is analyzed and verified in both AWGN and multipath Rayleigh fading channels. Theoretical developments including uniqueness of matrix factorization and algorithm convergence as well as complexity, are also provided. Simulation results demonstrate that our designed receiver yields smaller BER than benchmark schemes.