Kazuo Tanada

A parallel blind demodulator in the presence of intersymbol interference

This paper proposes a demodulator employing data detectors which do not need a known sequence for its startup, i.e., a parallel blind demodulator, in the presence of intersymbol interference (ISI). This demodulator operates as follows: (1) it includes multiple adaptive maximum-likelihood sequence estimations with per-survivor processing (PSP-MLSEs) respectively for different estimated channel memory lengths and different sampling timing thanks to over-sampling; (2) it selects the most reliable PSP-MLSE sequence according to reliability information. Thus, it uses the known sequence not for data detection and timing/parameter estimation but for the frame synchronization. Finally, computer simulations confirm that performance of this parallel blind demodulator is similar to that of the demodulator with the perfect timing/parameter information in the presence of ISI.

A Multiple-Symbol Differential Detection Based on Channel Prediction for Fast Time-Varying Fading

This paper discusses a generalized concept of multiple-symbol differential detection (MDD) and analytically derives weight parameters based on channel prediction for MDD on fast time-varying channels. At first, this paper shows that adaptive maximum-likelihood sequence estimation employing per-survivor processing (PSP-MLSE) with a single channel tap is similar concept to MDD. Next, the weight parameters for MDD are derived according to the channel estimation of PSP-MLSE based on a high order channel prediction. Finally, computer simulation confirms that MDD with the analytically derived parameters mitigates floor of bit error rate (BER) on fast time-varying fading channels without channel state information.

Performance of list Viterbi equalizers with metric-criteria combining

This paper discusses performance of a list Viterbi equalizer (LVE) employing a metric-criteria combining (MCC) scheme, which weighted-combines the squared Euclidean metric and the modified metric proposed by Ungerboeck (1974). First, it evaluates hardware implementation aspects of LVEs. Next, it discusses performance aspects of the metric criteria. Finally, it is confirmed by computer simulation that MCC-LVEs can cope with the path diversity gain at relatively small hardware complexity in the presence of wide spread ISI and MCC-LVEs with diversity reception improve the packet error rate (PER) performance even if there exist large number of effective fading paths.