# Joint Tilt Angle Adaptation and Beamforming in Multicell Multiuser Cellular Networks

## TL;DR

This paper proposes a joint beamforming and tilt angle adaptation method for multicell multi-user networks, significantly improving energy efficiency through an iterative fractional programming algorithm and user clustering based on elevation angles.

## Contribution

It introduces a novel iterative algorithm for joint beamforming and tilt angle optimization, enhancing energy efficiency in 3D beamforming for cellular networks.

## Key findings

- Achieves higher energy efficiency than 2D beamforming methods.
- Uses a fractional programming approach for non-convex optimization.
- Employs a greedy search for tilt angle adaptation.

## Abstract

3D beamforming is a promising approach for interference coordination in cellular networks which brings significant improvements in comparison with conventional 2D beamforming techniques. This paper investigates the problem of joint beamforming design and tilt angle adaptation of the BS antenna array for maximizing energy efficiency (EE) in downlink of multi-cell multi-user coordinated cellular networks. An iterative algorithm based on fractional programming approach is introduced to solve the resulting non-convex optimization problem. In each iteration, users are clustered based on their elevation angle. Then, optimization of the tilt angle is carried out through a reduced complexity greedy search to find the best tilt angle for a given placement of the users. Numerical results show that the proposed algorithm achieves higher EE compared to the 2D beamforming techniques.