Green Femtocell Networks through Joint Power Control and 3-Dimensional Pattern-Dependent Beamforming

Abstract

Femtocell technologies are used to extend radio coverage into buildings and provide wireless broadband access in residential, office or indoor hotspot environments. However, due to the radio spectrum scarcity, the femtocells reuse the same licensed spectrum bands of the macrocells. Thus interference management is one of the main challenges under such co-channel deployment of the femtocells. In this paper, we propose a new joint power control and 3-dimensional (3D) pattern-dependent beamforming algorithm to minimize total power consumption of the femtocells deployed in a macrocellular environment. This algorithm can help us achieve the goal of green communication and significantly reduce power consumption of the overall radio access networks. The algorithm is based on an iterative scheme for a downlink case where all femtocell access points (FAPs) and macro base stations (BSs) are equipped with multiple antennas. By considering radiation pattern of all antennas, the scheme tries to find the optimal 3D beamforming weights and transmission power of all FAPs and BSs while satisfying minimum signal-to-interference-plus-noise ratio (SINR) requirements of both macrocell and femtocell networks. Simulations are conducted in various scenarios to evaluate performance of the proposed algorithm.