Diversity Reception on Mobile Terminal under Slow Fading Environment

In recent years, television broadcasting can be received on mobile terminals in Japan since terrestrial digital television broadcasting (ISDB-T) has been initiated. In case of mobile reception, however, reception quality becomes worth because of fluctuation of received signal due to fading as shown in Fig.1 [1]. In general, burst error due to deep fading could be dispersed by time interleaving and relieved by forward error correction. However, duration of the burst error becomes long in case of slow fading and the errors can not be corrected sufficiently, especially in case of handy terminals [2]. As a counter measure for the above problem, we consider the utilization of diversity reception technique in this paper. For the diversity reception, plural antennas should be mounted on a terminal. But, it seems that enough element space could not be kept because the wave length in UHF band which utilized in ISDB-T is relatively long compared with the size of the handy terminals [3]. Moreover, scheme of the diversity switching and threshold of switching obviously affects on the effectiveness of the diversity reception. In this paper, effectiveness of several schemes of diversity reception in slow fading environment is compared and the optimal threshold is discussed. Furthermore, effect of Doppler shift and correlation between branches on bit error rate (BER) performance is described.