Optimal Cell Load and Throughput in Green Small Cell Networks with Generalized Cell Association

TL;DR

This paper analyzes the interactions between cell association, load, and throughput in energy-efficient small cell networks, highlighting the importance of accounting for void cells and deriving optimal load conditions for maximizing green throughput.

Contribution

It provides the first theoretical analysis of void cell probability under generalized cell association and derives optimal cell loads for green throughput maximization.

Findings

Void cell probability is significant and bounded by exp(-λ_U/λ_B).

Optimal cell load balances throughput and energy efficiency.

Theoretical solutions for optimal loads are validated by simulations.

Abstract

This paper thoroughly explored the fundamental interactions between cell association, cell load and throughput in a green (energy-efficient) small cell network in which all base stations form a homogeneous Poisson point process (PPP) of intensity $\lambda_B$ and all users form another independent PPP of intensity $\lambda_U$. Cell voidness, usually disregarded due to rarity in cellular network modeling, is first theoretically analyzed under generalized (channel-aware) cell association (GCA). We showed that the void cell probability cannot be neglected any more since it is bounded above by $\exp(-\lambda_U/\lambda_B)$ that is typically not small in a small cell network. The accurate expression of the void cell probability for GCA was characterized and it was used to derive the average cell and user throughputs. We learned that cell association and cell load $\lambda_U/\lambda_B$ significantly affect these two throughputs. According to the average cell and user throughputs, the green cell and user throughputs are defined respectively to reflect whether the energy of a base station is efficiently used to transmit information or not. In order to achieve satisfactory throughput with certain level of greenness, cell load should be properly determined. We presented the theoretical solutions of the optimal cell loads that maximize the green cell and user throughputs, respectively, and verified their correctness by simulation.