Hybrid chip-rate equalization of downlink CDMA in SFN channel

Abstract

We consider a simple downlink code division multiple access (CDMA) system in which user signals are transmitted in a single-frequency network (SFN) channel. The SFN channel has always been a problem in mobile communication or broadcasting channel due to its huge delay spread. Generally, we suffer from multiple access interference (MAI) caused by the multipath channel and MAI becomes worse when the terminal meets the SFN channel. In this paper we present a receiver algorithm which performs adaptive channel equalization efficiently in the harsh SFN mobile channel with considerably low complexity. We will cover some methods for a chip equalizer implementation and evaluate their performances in a simple short delay channel and SFN channel. Also, effects of frequency offsets of the base-station (repeater) are investigated as a consideration for practical applications.