Realistic discrete channel models for error control strategies evaluation

The evaluation of error control strategies for different wireless services implies the existence of models which can describe physical and data-link layers as a whole. We present discrete channel (DC) models for wireless services, which are based upon nested hidden Markov models (HMM) and take into account soft decision outputs. It is shown that realistic DC models based upon GSM and CDMA radio channels without FEC may have a relatively large number of channel states. The sequence of erroneous frames after decoding in most practical cases may be accurately represented by one-error-state Fritchman models. DC model parameters for ARQ and hybrid FEC-ARQ schemes are presented