On the resilience of cellular networks: how can national roaming help?

TL;DR

The paper addresses the resilience of cellular networks at a national scale and investigates how national roaming can enhance coverage and user experience. It combines public data and a physics-based system model to quantify resilience using $FDP$ and $FSP$ under random and region-based failures, including scenarios with full and partial roaming. Key contributions include a country-scale resilience assessment for the Dutch network, quantified gains from national roaming (up to $13\%$ improvement in $FDP$ and $55\%$ in $FSP$), and guidance on where and how roaming should be implemented (technology and urban/rural areas). The work provides a generalizable framework for regulators and operators to plan resilience-enhancing roaming agreements in other countries and under future network evolutions.

Abstract

Cellular networks have become one of the critical infrastructures, as many services depend increasingly on wireless connectivity. Therefore, it is important to quantify the resilience of existing cellular network infrastructures against potential risks, ranging from natural disasters to security attacks, that might occur with a low probability but can lead to severe disruption of the services. In this paper, we combine models with public data from national bodies on mobile network operator (MNO) infrastructures, population distribution, and urbanity level to assess the coverage and capacity of a cellular network at a country scale. Our analysis offers insights on the potential weak points that need improvement to ensure a low fraction of disconnected population (FDP) and high fraction of satisfied population (FSP). As a resilience improvement approach, we investigate in which regions and to what extent each MNO can benefit from infrastructure sharing or national roaming, i.e., all MNOs act as a single national operator. As our case study, we focus on Dutch cellular infrastructure and model risks as random failures, correlated failures in a geographic region, and abrupt increase in the number of users. Our analysis shows that there is a wide performance difference across MNOs and geographic regions in terms of FDP and FSP. However, national roaming consistently offers significant benefits, e.g., up to 13% improvement in FDP and up to 55% in FSP when the networks function without any failures.

Figures (9)

• Figure 1: An illustration of the considered system model with two MNOs, MNO$_{\textrm{1}}$ (with subscribers $u_1$ and $u_3$) and MNO$_{\textrm{2}}$ (with subscribers $u_2$ and $u_4$). MNO$_1$'s coverage hole can be filled with MNO$_2$'s base station BS$_3$ to serve $u_3$. Moreover, to have a stronger signal, $u_2$ can connect to MNO$_1$'s BS$_1$.
• Figure 2: An example entry from the data set. For every BS, the following information is available: the provider, place, height, angle, frequency, power, reproduced fromantennekaart.
• Figure 3: Number of users per BS and BS density (km$^2$) per province.
• Figure 4: FDP, FSP, and achieved gains from national roaming for the three MNOs in different provinces.
• Figure 5: FDP and FSP in Amsterdam under only roaming for a specific technology (5G, 4G or 3G).