A mobility prediction scheme of LTE/LTE-A femtocells under different velocity scenarios

Femtocells have been standardized by the Third-Generation Partnership Project (3GPP) technical specifications to be placed indoors and in the cell edge. Femtocells extend the coverage area and fulfil the upcoming demands of higher data rates. However, as a result of the mass deployment of femtocells, users experience extra delay and unnecessary handovers. This can severely influence the Quality of Service (QoS) of delay-sensitive Real-Time (RT) applications such as Voice over Long Term Evolution (VoLTE). 3GPP LTE/LTE-A wireless networks aim to ensure seamless mobility and fast handover support to RT and non-RT application services under high mobility. Mobility prediction is an effective technique to identify a future evolved and Home NodeB (eNB/HeNB) in advance, improve overall network QoS and satisfy end-user experience. This study investigates the role of mobility prediction in reducing VoLTE end-to-end delay and handover delay under different User Equipment (UE) velocities in mixed femtocell and macrocell environments. A mobility prediction scheme based on the user's path and Reference Signal Received Power and Reference Signal Received Quality (RSRP/RSRQ) measurements with mixed RT and non-RT traffic is proposed and then evaluated using a novel network model. The simulation results reveal that the proposed scheme has clearly reduced handover delay by 29%, kept VoLTE end-to-end delay within the ITU-T standard recommendations and maintained the desired QoS.