Component Carrier Selection Based on User Mobility for LTE-Advanced Systems

Abstract

In component carrier (CC) selection of carrier aggregation, it is critically significant to take the effect of user mobility on system performance into consideration. In the previous CC selection schemes, in order to guarantee channel quality and avoid frequent CC handover caused by user mobility, the eNB always select the CC with the highest Reference Signal Receiving Power (RSRP) for users. However, this method would face carrier overload when the CC with high RSRP was selected for a majority of users. On the contrary, in conventional schemes considering carrier load balancing, the system would face the problem of frequent CC reselection/handover as user mobility was usually neglected, which would face unaffordable signaling overhead and time delay. In this paper, a user-mobility based CC selection (UM-CS) scheme is proposed to analyze the influence of user mobility on CC selection and achieve a compromise of carrier load balancing and handover number. In the proposed UM-CS scheme, in order to avoid frequent CC handover, the eNB-UE separation after a given time is estimated according to the user's mobility and CCs that can satisfy the coverage margin are selected into the user's candidate CC set. In the set, the CC with larger coverage takes higher priority in CC selection. Carrier load are balanced as the user can only select CCs from its own candidate CC set and a CC can be selected only when its carrier load balancing factor is not higher than the threshold. Simulation results validate the effectiveness of the proposed scheme in terms of carrier load balancing and handover number under different user mobility.