Robust adaptive frequency-domain equalization for DS-CDMA in non-Gaussian noise channels

Adopting frequency-domain equalization (FDE) in DS-CDMA can partially restore the orthogonality of users and suppress multiple-access interference (MAI). The existing FDEs are designed with the assumption of additive white Gaussian noise. Although the assumption is quite proper for a variety of applications, it has been revealed that many background noises arising in the reality are with non-Gaussian statistics. In this paper, we show that the Gaussian-based FDEs fare poorly in non-Gaussian noise environment. To achieve reliable data transmission in frequency-selective multiple-access channel with unknown non-Gaussian noise, we propose a robust adaptive FDE which consists of a nonlinear preprocessing front-end followed by a linear adaptive FDE. The nonlinear front-end adapts itself to the unknown non-Gaussian noise to suppress the impulses while the FDE effectively removes the MAI. Results from the simulation reveal that the proposed robust FDE is able to perform successfully in both Gaussian and non-Gaussian noise environments.