On Idle Mode Mobility State Detection in Evolved UTRAN

In this paper we present different idle mode mobility state detection mechanisms targeted for 3GPP Evolved UTRAN. The purpose is to study the reliability of the mobility state detection mechanism specified in 3GPP TS 36.304 for 3GPP Release 8 in varying conditions, such as different re-selection thresholds, UE velocities and inter-site distances. Three mobility states have been defined in TS 36.304 based on occurred cell re-selections in a certain time window. According to small inter-site distance simulations, pedestrian speeds (normal mobility state) can be detected with a quite satisfactory accuracy but distinguishing the medium and high mobility states is quite challenging, since UEs are experiencing quite large variance in number of re-selections with the same UE velocities. Simulations with large inter-site distances show similar results.