# Downlink Small-cell Base Station Cooperation Strategy in Fractal Small-cell Networks

## TL;DR

This paper analyzes cooperative strategies for small-cell base stations in fractal small-cell networks, showing how signal constraints affect achievable rates and energy efficiency, with implications for network deployment.

## Contribution

It derives new formulas for achievable rates under different constraints in fractal small-cell networks using an anisotropic path loss model.

## Key findings

- Received signal power constraint yields higher rates than distance constraint.
- Achievable rate decreases as SBS density increases under anisotropic path loss.
- Energy efficiency declines with increased SBS density, posing deployment challenges.

## Abstract

Coordinated multipoint (CoMP) communications are considered for the fifth-generation (5G) small-cell networks as a tool to improve the high data rates and the cell-edge throughput. The average achievable rates of the small-cell base stations (SBS) cooperation strategies with distance and received signal power constraints are respectively derived for the fractal small-cell networks based on the anisotropic path loss model. Simulation results are presented to show that the average achievable rate with the received signal power constraint is larger than the rate with a distance constraint considering the same number of cooperative SBSs. The average achievable rate with distance constraint decreases with the increase of the intensity of SBSs when the anisotropic path loss model is considered. What's more, the network energy efficiency of fractal smallcell networks adopting the SBS cooperation strategy with the received signal power constraint is analyzed. The network energy efficiency decreases with the increase of the intensity of SBSs which indicates a challenge on the deployment design for fractal small-cell networks.