Understanding mobile network quality and infrastructure with user-side measurements

Measurement collection is a primary step towards analyzing and optimizing performance of a telecommunication service. With an Mobile Broadband (MBB) network, the measurement process has not only to track the network’s Quality of Service (QoS) features but also to asses a user’s perspective about its service performance. The later requirement leads to “user-side measurements” which assist in discovery of performance issues that makes a user of a service unsatisfied and finally switch to another network. User-side measurements also serve as first-hand survey of the problem domain. In this thesis, we exhibit the potential in the measurements collected at network edge by considering two well-known approaches namely crowdsourced and distributed testbed-based measurements. Primary focus is on exploiting crowdsourced measurements while dealing with the challenges associated with it. These challenges consist of differences in sampling densities at different parts of the region, skewed and non-uniform measurement layouts, inaccuracy in sampling locations, differences in RSS readings due to device-diversity and other non-ideal measurement sampling characteristics. In presence of heterogeneous characteristics of the user-side measurements we propose how to accurately detect mobile coverage holes, to devise sample selection process so to generate a reliable radio map with reduced sample cost, and to identify cellular infrastructure at places where the information is not public. Finally, the thesis unveils potential of a distributed measurement test-bed in retrieving performance features from domains including user’s context, service content and network features, and understanding impact from these features upon the MBB service at the application layer. By taking web-browsing as a case study, it further presents an objective web-browsing Quality of Experience (QoE) model

SURVEY OF HISTORY BASED ROUTING PROTOCOLS IN DELAY TOLERANT NETWORK

Frequent changes in topology and the lack of infrastructure compel disrupted networks to avoid the use of traditional routing protocols. Rather than defining paths towards destinations, the routing tables store access chances of known nodes towards a specific destination. History of a node’s encounter is maintained in three different ways to find out its power of access to the rest of network nodes. The survey paper discusses various routing schemes based on the past encounter patterns of network nodes.Keywords: (Delay Tolerant Network) DTN; routing protocols; history-based routing; frequency; encounter; inter-contact duration;  recency

Impact of Bushfire Dynamics on the Performance of MANETs

In emergency situations like recent Australian bushfires, it is crucial for civilians and firefighters to receive critical information such as escape routes and safe sheltering points with guarantees on information quality attributes. Mobile Ad-hoc Networks (MANETs) can provide communications in bushfire when fixed infrastructure is destroyed and not available. Current MANET solutions, however, are mostly tested under static bushfire scenario. In this work, we investigate the impact of a realistic dynamic bushfire in a dry eucalypt forest with a shrubby understory, on the performance of data delivery solutions in a MANET. Simulation results show a significant degradation in the performance of state-of-the-art MANET quality of information solution. Other than frequent source handovers and reduced user usability, packet arrival latency increases by more than double in the 1st quartile with a median drop of 74.5% in the overall packet delivery ratio. It is therefore crucial for MANET solutions to be thoroughly evaluated under realistic dynamic bushfire scenarios

Measuring and Localising Congestion in Mobile Broadband Networks

Mobile broadband networks, although increasingly popular, suffer large fluctuations in performance. Download speeds can drop by 50% or more during peak hours. Hence, understanding and dissecting the causes of these fluctuations is central to improving current and future networks. In this paper, we propose a congestion detection and localisation method, Q-TSLP, that combines and extends the two state-of-the-art congestion detection tools: Q-Probe and TSLP. Q-Probe monitors patterns in packet arrivals, while TSLP tracks shifts in RTT to detect bottleneck at different segments of an end-to-end path. QProbe can attribute congestion, at a very coarse level, to either radio or non-radio related. TSLP on the other hand cannot pinpoint radio related congestion. Q-TSLP provides a per-hop congestion attribution thus addressing these limitations. To this end, we build two small scale LTE testbeds and experiment with a series of congestion scenarios. These controlled experiments show that apart from correct congestion localisation to finer granularity, the detection accuracy improves significantly with Q-TSLP, up to 100% in some cases. We then run a three-month long measurement campaign of congestion over two commercial operators in Norway. Overall, we run 17 million tests from a large number of geographically distributed probes. We find that both operators suffer congestion at different parts of the network. Our findings indicate that apart from mobile radio access, a non-trivial fraction of cases is related to congested mobile operator and Internet paths beyond the mobile network core. These findings hint that operators may need significant infrastructure upgrades to cope with potential 5G traffic volumes

Quality of information with minimum requirements for emergency communications

In emergency situations like the recent Australian bushfires, it is crucial for civilians and firefighters to receive critical information such as available escape routes with guarantees on accuracy, timeliness, reliability, and completeness. Mobile Ad-hoc Networks (MANETs) can provide communications in bushfires but guaranteeing information delivery that meets user needs is not easy with current MANET forwarding solutions. Quality of Information (QoI) based source selection has recently been developed in MANETs for this purpose. The most popular QoI scheme uses the analytic hierarchy process (AHP), an intensive pairwise comparison procedure to score sources using a linear combination of low-level network metrics in a hierarchical two-step process. Current QoI-AHP, by directing traffic to a single high scoring source, often creates additional bottlenecks and does not guarantee the higher-level information needs of users. In this work, we develop a novel low overhead source selection scheme, QoI with Thresholds (QoIT), that is designed to deliver the required target performance thresholds for users. QoIT introduces two modifications to QoI-AHP. Firstly, it replaces the raw network performance value by the ratio of the network metric value to the user’s demand for that performance, a goodness measure of how far the value of the network metric is from meeting the user’s demand. The ratios are fed into QoIT’s process for assigning multi-dimensional scores to each source. Secondly, QoIT uses new source selection criteria to choose the source that best delivers the information that meets the user needs. To evaluate QoIT and QoI-AHP performances in emergency communications, we develop a novel simulation software with realistic models across multiple network layers. Our QoIT algorithm works with any combination of quality thresholds for any subset of network metrics. Simulation results show that QoIT out-performs QoI-AHP by increasing user usability by 57%, ensuring high priority requirements are met, reducing source bottlenecks, and decreasing the source selection time by 62.5%

Implementation and Analysis of Clustering Techniques Applied on Pocket Switched Network

Clustering is an extraction of closely knitted groups from a set of nodes. Its benefits in social network range from applying marketing schemes on an appropriate interest group to social network analysis. It is also considered an important tool for efficient communication in an intermittent Pocket Switched Network (PSN). Contact probability between mobile devices in disrupted social networks greatly depends upon the mobility profile and level of relationships between the device holders. Unlike flat routing, scalable and efficient routing in these networks is highly dependent upon accurate derivation of social circles or clusters. This paper therefore evaluates existing clustering techniques for terrestrial social network with the end aim of minimizing communication overhead by identifying those message carriers that can bring message closer to destination node. In order to ensure intercluster routing, modification in existing schemes is proposed so as to detect bridge nodes between single hop destination clusters and to find path towards a disjoint destination cluster

A Live Demonstration of In-Band Telemetry in OSM-Orchestrated Core Networks

Network Function Virtualization is a key enabler to building future mobile networks in a flexible and cost-efficient way. Such a network is expected to manage and maintain itself with minimum human intervention. With early deployments of the fifth generation of mobile technologies – 5G – around the world, setting up 4G/5G experimental infrastructure is necessary to optimally design Self-Organising Networks (SON). In this demo, we present a custom small-scale 4G/5G testbed. As a step towards self-healing, the testbed integrates Programming Protocol-independent Packet Processors (P4) virtual switches, that are placed along interfaces between different components of transport and core network. This demo not only shows the administration and monitoring of the Evolved Packet Core VNF components, using Open Source MANO, but also serves as a proof of concept for the potential of P4-based telemetry in detecting anomalous behaviour of the mobile network, such as a congestion in the transport part