Stochastic Geometry Analysis of Multi-Antenna Two-Tier Cellular Networks

TL;DR

This paper uses stochastic geometry to analyze multi-antenna two-tier cellular networks, deriving data rate expressions and exploring how system parameters influence performance and area spectral efficiency.

Contribution

It provides simplified approximations for user data rates and identifies optimal active user numbers and conditions under which range expansion enhances ASE.

Findings

Differences in density and power significantly impact user data rates.

Optimal active users are roughly a fixed portion of antennas plus one.

Range expansion improves ASE when macro base stations have many more antennas.

Abstract

In this paper, we study the key properties of multi-antenna two-tier networks under different system configurations. Based on stochastic geometry, we derive the expressions and approximations for the users' average data rate. Through the more tractable approximations, the theoretical analysis can be greatly simplified. We find that the differences in density and transmit power between two tiers, together with range expansion bias significantly affect the users' data rate. Besides, for the purpose of area spectral efficiency (ASE) maximization, we find that the optimal number of active users for each tier is approximately fixed portion of the sum of the number of antennas plus one. Interestingly, the optimal settings are insensitive to different configurations between two tiers. Last but not the least, if the number of antennas of macro base stations (MBSs) is sufficiently larger than that of small cell base stations (SBSs), we find that range expansion will improve ASE.