The near ubiquitous availability and success of mobile broadband networks has motivated verticals that range from public safety communication to intelligent transportation systems and beyond to consider choosing them as the communication mean of choice. Several of these verticals, however, expect high availability of multiple nines. This paper leverages end-to-end measurements to investigate the potential of current mobile broadband networks to support these expectations. We conduct a large-scale measurement study of network availability in four networks in Norway. This study is based on three years of measurements from hundreds of stationary measurement nodes and several months of measurements from four mobile nodes. We find that the mobile network centralized architecture and infrastructure sharing between operators are responsible for a non-trivial fraction of network failures. Most episodes of degraded availability, however, are uncorrelated. We also find that using two networks simultaneously can result in more than five nines of availability for stationary nodes and three nines of availability for mobile nodes. Our findings point to potential avenues for enhancing the availability of future mobile networks.

This paper demonstrates that end-to-end active measurements can give invaluable insights into the nature and characteristics of packet loss in cellular networks. We conduct a large-scale measurement study of packet loss in four UMTS networks. The study is based on active measurements from hundreds of measurement nodes over a period of one year. We find that a significant fraction of loss occurs during pathological and normal Radio Resource Control (RRC) state transitions. The remaining loss exhibits pronounced diurnal patterns and shows a relatively strong correlation between geographically diverse measurement nodes. Our results indicate that the causes of a significant part of the remaining loss lie beyond the radio access network.

Mobile broadband networks play an increasingly important role in society, and there is a strong need for independent assessments of their robustness and performance. A promising source of such information is active end-to-end measurements. It is, however, a challenging task to go from individual measurements to an assessment of network reliability, which is a complex notion encompassing many stability and performance related metrics. This paper presents a framework for measuring the user-experienced reliability in mobile broadband networks. We argue that reliability must be assessed at several levels, from the availability of the network connection to the stability of application performance. Based on the proposed framework, we conduct a large-scale measurement study of reliability in 5 mobile broadband networks. The study builds on active measurements from hundreds of measurement nodes over a period of 10 months. The results show that the reliability of mobile broadband networks is lower than one could hope: more than 20% of connections from stationary nodes are unavailable more than 10 minutes per day. There is, however, a significant potential for improving robustness if a device can connect simultaneously to several networks. We find that in most cases, our devices can achieve 99.999% ("five nines") connection availability by combining two operators. We further show how both radio conditions and network configuration play important roles in determining reliability, and how external measurements can reveal weaknesses and incidents that are not always captured by the operators' existing monitoring tools.

We present Nornet Edge (NNE), a dedicated infrastructure for measurements and experimentation in mobile broadband networks. NNE is unprecedented in size, consisting of more than 400 measurement nodes geographically distributed all over Norway. Each measurement node is a Linux-based embedded computer, and is connected to multiple mobile broadband providers. In addition, NNE includes an extensive backend system for deploying and managing experiments and collecting data. NNE makes it possible to run long-term measurement experiments to assess and compare quality and performance across different network operators on a national scale. Particular focus is put on allowing experiments to run in parallel on multiple network connections, and on collecting rich context information related to the experiments. In this paper we give a detailed presentation of NNE, and describe three different measurement experiments that illustrate how the infrastructure can be used. We also provide a roadmap for further development of NNE.