Quantized Viterbi Algorithm: Maximum Likelihood Sequence Detection for SIMO ISI Channels with Low-Precision ADCs

This paper considers a single-input multiple-output (SIMO) wide-band communication system that uses low-precision analog-to-digital converters (ADCs) for quantizing the received signal. The key contribution of this paper is to propose an optimal maximum likelihood sequence detector (MLSD), which is referred to as a quantized Viterbi algorithm, extending to the quantized output case of the conventional Viterbi algorithm. In addition, a variant of the quantized Viterbi algorithm is proposed, which is robust to the effect of channel estimation errors. One major observation is that it is possible to achieve low symbol- error-rates in the inter-symbol interference channel even with one-bit ADCs, provided that the number of receive antennas is sufficiently large. Simulations demonstrate that the proposed algorithm is more robust to the channel estimation error than the conventional Viterbi algorithm, which simply treats the channel estimation error as an additional noise.