Cluster lifetime characterization for vehicular communication channels

Simulating the time-variance of vehicular channels correctly remains a challenging topic. We are interested in parsimonious mathematical channel models, in which only significant groups of multipath components (MPCs) are included. The MPCs are grouped in the delay-Doppler domain, which enables the development of cluster-based channel models. However, the characterization of time-variant vehicular channel parameters based on a joint clustering-and-tracking framework has not been adequately studied previously. In this paper, we focus on the cluster lifetime characterization for vehicular communication channels. A joint cluster identification-and-tracking approach based on the local scattering function (LSF) is applied, which takes the delay and Doppler domains into consideration. The proposed approach uses a density-based spatial clustering of applications with noise (DBSCAN) algorithm for identification. The cluster centroid tracking is based on the multipath component distance (MCD) matrix. We apply this approach to real-world vehicular channel measurements. The time-varying cluster lifetimes are tracked according via the cluster centroids for two scenarios. The results indicate that the detected cluster related to the line-of-sight (LOS) component persists throughout the measurement run and contributes the highest gain level for both scenarios. The clusters detected from traffic signs and large moving vehicles also persist for a longer period, whereas many clusters associated with discrete scatterers along the roadside appear for very short periods.