Pico Cell Range Expansion with Interference Mitigation toward LTE-Advanced Heterogeneous Networks

Deploying Pico eNodeBs (PeNBs) throughout a Macro cell layout is a promising solution to enhance system capacity and user throughput. However, strong received power from Macro eNodeBs (MeNBs) makes the Pico cell areas narrow. This causes limited cell splitting gain. Cell Range Expansion (CRE), which allows a User Equipment (UE) to be served by a cell with weaker received power, is simple and typical one of alternative cell associations to enhance offloading but it causes downlink (DL) interference issue in not only data and also control channels (CCHs). In this paper, we investigate performance of CRE with various bias settings and show that a moderate bias setting is effective to enhance capacity and user throughput. With respect to the DL interference issue in CCHs, we propose to support coordination of Lightly Loaded CCH transmission Subframe (LLCS) in LTE-Advanced.