ISI AND CCI CANCELER WITH PRESELECTING ADAPTIVE ARRAY AND CASCADED EQUALIZER IN DIGITAL MOBILE RADIO

An adaptive array has been proposed as a canceller for both inter-symb ol interference (ISI) and co-channel interference (CCI). However, it h as no path-diversity gain since it selects just one signal correlated to the reference signal. In this paper, a novel interference canceller having sufficient path-diversity gain is proposed. The canceller is c haracterized by the combined configuration of an adaptive array and an equalizer. In the proposed system, a pre-selecting adaptive array is installed first. By employing a specific training sequence and samplin g timing at the receiver during the training period, the perfect corre lation between the ''desired signal'' and ''short delayed ISI'' is ach ieved. Therefore, the preselecting adaptive array can extract the desi red and ISI signals simultaneously, and the cascaded adaptive equalize r can provide the path-diversity gain without degradation by interfere nce. The proposed system achieves a simple configuration and robustnes s against both ISI and CCI with a sufficient path diversity gain. In c omputer simulations, average BER characteristics of the proposed syste m were evaluated in a quasi-static Rayleigh fading channel. The simula tion results showed that the system can reduce both long-delayed ISI a nd CCI efficiently, and that the expected path diversity gain is obtai ned even with strong CCI. They also show ed that the degradation is no t so serious when the number of antenna elements is less than that of incoming signals.