(A) study on cell range expansion considering geometric information of pico cell in heterogeneous network

Abstract

We considered heterogeneous network that consists of macrocells overlaid by smallcells, e.g., microcells, femtocells and picocells. In heterogeneous network, coverage area of macro cell is larger than small cell, which leads to unbalance of load among base stations. In order to bolster it, cell range expansion (CRE) was proposed to offload some users from macro base station (MBS) to pico base station (PBS) and increase sum-rate as well by imposing a bias to received power from PBS. However, the offloaded user suffers high interference from MBS which leads to degradation of sum-rate of overall system. Therefore, inter-cell interference coordination (ICIC) is required with CRE as well. In this paper, a novel CRE scheme with interference coordination in heterogeneous multi-input multi-output multiuser wireless network is proposed. Different CRE bias is imposed to received power from PBS regarding the distance between MBS and PBS. MBS does interference coordination for pico cell users in order to overcome the drawback of CRE. Numerical results show that proposed scheme provides maximum sum rate regardless of the position of PBSs. Furthermore, they also show that more balanced loading can be achieved through the proposed scheme.