Viterbi equalization technologies for mobile broadband systems

摘要

This article reports on a list-output Viberbi equalizer developed at Mitsubishi Electric for implementing multimedia applications in a mobile environment. The authors propose an algorithm for selecting and combining metric criteria based onestimated channel characteristics and developed an algorithm for high-speed compare-select operation.Multimedia data transmissions in a mobile communication environment require high quality at a high data rate. However, increasing the data transmission rate leads to serious performance degradation due to increased vulnerability to fading effects causedby reflections and waveform distortion effects caused by variations in signal propagation speed along the transmission path. Specifically, at data rates above 10Mbps, delay effects can span from ten to several tens of bits. Viterbi equalizers and otheradaptive equalizers can be effective under these conditions; however, correcting dispersion effects at higher data rates requires additional hardware complexity with reduced processing delay at the same time.