Blind Adaptive Subcarrier Combining Technique for MC-CDMA Receiver in Mobile Rayleigh Channel

TL;DR

This paper introduces a blind adaptive subcarrier combining method for MC-CDMA receivers in mobile Rayleigh channels, enhancing interference suppression and channel tracking without needing channel knowledge, thus improving performance.

Contribution

It presents a novel blind adaptive combining technique that exploits spreading sequence structure for interference suppression and implicit channel tracking in MC-CDMA systems.

Findings

Improved BER performance under high Doppler rates

Enhanced user capacity with similar complexity to conventional methods

Effective interference suppression without channel knowledge

Abstract

A new subcarrier combining technique is proposed for MC -CDMA receiver in mobile Rayleigh fading channel. It exploits the structure formed by repeating spreading sequences of users on different subcarriers to simultaneously suppress multiple access interference (MAI) and provide implicit channel tracking without any knowledge of the channel amplitudes or training sequences. This is achieved by adaptively weighting each subcarrier in each symbol period by employing a simple gradient descent algorithm to meet the constant modulus (CM) criterion with judicious selection of step-size. Improved BER and user capacity performance are shown with similar complexity in order of O(N) compared with conventional maximum ratio combining and equal gain combining techniques even under high channel Doppler rates.