Time- and Frequency-Varying K -Factor of Non-Stationary Vehicular Channels for Safety-Relevant Scenarios

Laura Bernado, Thomas Zemen, Fredrik Tufvesson, Andreas Molisch, Christoph F. Mecklenbrauker

Research output: Contribution to journalArticlepeer-review

60 Citations (SciVal)


Vehicular communication channels are characterized by a non-stationary time- and frequency-selective fading process due to fast changes in the environment. We characterize the distribution of the envelope of the first delay bin in vehicle-to-vehicle channels by means of its Rician $K$-factor. We analyze the time–frequency variability of this channel parameter using vehicular channel measurements at 5.6 GHz with a bandwidth of 240 MHz for safety-relevant scenarios in intelligent transportation systems (ITS). This data enables a frequency-variability analysis from an IEEE 802.11p system point of view, which uses 10 MHz channels. We show that the small-scale fading of the envelope of the first delay bin is Rician distributed with a varying K-factor. The later delay bins are Rayleigh distributed. We demonstrate that the K-factor cannot be assumed to be constant in time and frequency. The causes of these variations are the frequency-varying antenna radiation patterns, as well as the time-varying number of active scatterers, and the effects of vegetation. We also present a simple but accurate bimodal Gaussian mixture model, which allows to capture the K-factor variability in time for safety-relevant ITS scenarios.
Original languageEnglish
Pages (from-to)1007-1017
JournalIEEE Transactions on Intelligent Transportation Systems
Issue number2
Publication statusPublished - 2015

Subject classification (UKÄ)

  • Electrical Engineering, Electronic Engineering, Information Engineering


  • Channel modelling
  • intelligent transportation systems
  • non-stationary fading
  • Rician K-factor
  • safety-relevant scenarios
  • vehicle-to-vehicle links


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