A multi-point transmission scheme for cross-tier interference mitigation in downlink heterogeneous networks

Abstract

Heterogeneous network (HetNet) deployment comprising of high power macro nodes overlaid with pico nodes and various other types of low power nodes has been considered as one of the key enabling technology in 3GPP LTE-Advanced. HetNet can significantly enhance the capacity and coverage of cellular networks. However, severe inter-cell interference (ICI) between high power macro and low power pico nodes is a critical performance limiting factor for cell-edge users in HetNet. Coordinated multipoint transmission (CoMP) has been recognized as an effective technique to mitigate ICI in LTE-A. However, backhaul overhead and complexity are critical issues in CoMP. In this paper we propose a novel scheme that utilizes the benefits of HetNet to improve the system capacity and coverage. Moreover it exploits coordinated multi-point transmission to effectively mitigate ICI with reduced feedback overhead and complexity. In our scheme the users with high signal to interference plus noise ratio are served by the respective macro and pico cells. However, for users in high interference region, coordinated multi-point joint transmission is adopted to increase the radio signal strength and effectively mitigate ICI. The proposed scheme outperforms the conventional system with reduced backhaul overhead and complexity. System level simulations illustrate that the proposed scheme attains higher performance as compared to conventional schemes.