Adaptive equalization and Viterbi decoding for digital mobile radio systems

The application of Viterbi decoding on multipath fading mobile radio channels is investigated with reference to the GSM pan-European mobile radio system. Attention is focused on traffic channels for speech transmission which are protected from channel impairments by means of two concatenated codes. At the receiver, the Viterbi algorithm is used for decoding the inner convolutional code. The capabilities of an MLSE (maximum likelihood sequence estimation) receiver have been enhanced with a channel state estimator in order to supply the Viterbi decoder with channel measurement information. Hard decision Viterbi decoding and hard CSI (channel state information) have been assumed, reaching a gain of about 2 dB with respect to traditional Viterbi decoders. Simulation and mixed laboratory and simulation results are presented which show the performance of the Viterbi decoder in different multipath environments