On the importance of error memory in UMTS radio channel emulation using hidden Markov models (HMM)

The possibility to change data rate in 10 milliseconds is one of the innovative features of the Universal Mobile Telecommunications System (UMTS). This change results in a different mobile channel with different burst error characteristics that can be modelled and its effects can be emulated by hidden Markov models (HMM) which are computationally more efficient than waveform level models. Thus the data rate change in the wideband CDMA (WCDMA) channel supposes to change the HMM. This change from one HMM to another can be performed considering the number of errors in the last frame or not. In this paper the impact of error memory when the channel is emulated by HMM change, is presented.