Dynamic power control of Pico Base Stations in cooperation clusters towards amorphous coverage

In heterogeneous networks, Cell Range Expansion (CRE) is presented to expand the coverage area of the Pico Base Station (PBS). However, the Pico User Located in the CRE (CRE UE) can suffer server interference from the Macro Base Station (MBS). The existing interference cooperation schemes which the MBS stops transmitting or decreases transmission power can improve the performance of CRE UEs, but may result in the throughput loss of Macro Users (MUEs). To address the issue, the dynamic power control of the PBS in cooperation clusters is proposed to balance the performance of the CRE UE and the MUE. Unlike the existing studies, PBSs can cooperate to serve the CRE UE thus implementing amorphous coverage and every PBS in cooperation clusters dynamically increases its transmission power to protect the CRE UE from the interference. We maximize the weighted objective function to optimize the increased transmission power per PBS and the ratio of resources which the PBS increases transmission power. Simulation results show that while ensuring the satisfactory system average throughput, the proposed scheme greatly improves the throughput of the CRE UE, and reduces the performance loss of the MUE as compared to the traditional approaches.