Enhancing LTE-Advanced Relay Deployments via Biasing in Cell Selection and Handover Decision

Decode-and-forward relaying is a promising enhancement to current radio access networks and is now being standardized in the 3GPP work item on LTE-Advanced. Relay enhanced networks are expected to fulfill the demanding coverage and capacity requirements in a cost-efficient way. However, due to the low transmit power characteristic of relay nodes, their coverage areas will be relatively small in the overlaying macro cell. Therefore, the performance of relay deployments may be limited by load imbalances, unless system parameters are properly selected. In this paper, we propose a practical solution for this problem by introducing a bias to cell selection and handover thresholds. By applying the bias, the relay cells can be extended and an appropriate load balance can be achieved. Via a comprehensive system level simulation campaign, it is shown that biasing results in significant user throughput improvements in both the uplink and the downlink.