Mobility State Estimation in LTE

Estimating mobile user speed is a major issue which has significant impacts to radio resource management and also to the mobility management of LTE networks. This paper introduces two algorithms that can estimate the speed of mobile users, have low computational requirement, and do not require any modification to today's user device or standard protocol. The proposed methods rely on uplink (UL) sounding reference signal (SRS) power measurements performed at the eNodeB (eNB) and are effective even under very large sampling periodicity (e.g., 40 ms or more). Indeed, the two proposed methods allow to be implemented at the base station or at the mobile user equipment (UE) depending on system or implementation preference. We evaluate the effectiveness of our algorithms using realistic data specified and provided by Layer 1 eNB Alcatel Lucent team. Results show that the classification of UE's speed required by LTE can be achieved with high accuracy. In addition, they have minimal impact to the CPU and memory of eNB modem. We see that they are very practical to today's LTE networks and would allow a continuous and real-time UE speed estimation.