MeDeHa - Efficient Message Delivery in Heterogeneous Networks with Intermittent Connectivity

In this report, we present an efficient message delivery mechanism that enables distribution/dissemination of messages in an internet connecting heterogeneous networks and prone to disruptions in connectivity. We call our protocol MeDeHa (pronounced ``medea'') for Message Delivery in Heterogeneous, Disruption-prone Networks. MeDeHa is complementary to the IRTF's Bundle Architecture: while the Bundle Architecture provides storage above the transport layer in order to enable interoperability among networks that support different types of transport protocols, MeDeHa is able to store data at any layer of the network stack, addressing heterogeneity even at lower layers (e.g., when intermediate nodes do not support higher-layer protocols). MeDeHa also takes advantage of network heterogeneity (e.g., nodes supporting more than one network and nodes having diverse resources) to improve message delivery. For example, in the case of IEEE 802.11 networks, participating nodes may use both infrastructure- and ad hoc modes to deliver data to otherwise unavailable destinations. Another important feature of MeDeHa is that it does not rely on special-purpose nodes such as message ferries, data mules, or throwboxes in order to relay data to intended destinations, and/or to connect to the backbone network wherever infrastructure is available. The network is able to store data destined to temporarily unavailable nodes for some time depending upon current storage availability as well as quality-of-service needs (e.g., delivery delay bounds) imposed by the application. We showcase MeDeHa's ability to operate in environments consisting of a diverse set of interconnected networks and evaluate its performance via extensive simulations using a variety of synthetic-- as well as more realistic scenarios. Our results show significant improvement in average delivery ratio and significant decrease in average delivery delay in the face of episodic connectivity. We also demonstrate MeDeHa's support for different levels of quality-of-service through traffic differentiation and message prioritization

Coping with Episodic Connectivity in Heterogeneous Networks

International audienceIn this paper, we present an efficient message delivery mechanism that enables distribution/dissemination of messages in an internet connecting heterogeneous networks and prone to disruptions in connectivity. We call our protocol MeDeHa (pronounced “medea”) for Message Delivery in Heterogeneous, Disruptionprone Networks. MeDeHa is complementary to the IRTF's Bundle Architecture: while the Bundle Architecture provides storage above the transport layer in order to enable interoperability among networks that support different types of transport layers, MeDeHa stores data at the link layer addressing heterogeneity at lower layers (e.g., when intermediate nodes do not support higher-layer protocols). MeDeHa also takes advantage of network heterogeneity (e.g., nodes supporting more than one network) to improve message delivery. For example, in the case of IEEE 802.11 networks, participating nodes may use both infrastructure- and ad hoc modes to deliver data to otherwise unavailable destinations. Another important feature of MeDeHa is that there is no need to deploy special-purpose nodes such as message ferries, data mules, or throwboxes in order to relay data to intended destinations, or to connect to the backbone network wherever infrastructure is available. The network is able to store data destined to temporarily unavailable nodes for some time depending upon existing storage as well as quality-of-service issues such as delivery delay bounds imposed by the application. We evaluate MeDeHa via simulations using indoor scenarios (e.g. convention centers, exposition halls, museums etc.) and show significant improvement in delivery ratio in the face of episodic connectivity. We also showcase MeDeHa's support for different levels of quality-of-service through traffic differentiation and message prioritization

Store and Haul: Improving Mobile Ad-Hoc Network Connectivity through Repeated Controlled Flooding

This work investigates the benefits and drawbacks of repeating controlled flooding at different intervals in mobile ad hoc networks (MANETs) to overcome episodic connectivity. Specifically, the thesis examines the efficiencies in repeating transmissions by quantifying the packet delivery ratio (PDR) and recording the resulting delays in different types of MANET scenarios. These scenarios mainly focus on partitions within the simulated networks by varying node density and mobility. The nodes store transmitted data and haul it across the MANET in the hope that it will come in range of a node that leads to the destination. A customized version of the Network Simulator 2 (ns-2) is used to create the simulations. A qualitative analysis follows and shows the cost and benefits of increased transmissions at varied time intervals

Hybrid Routing in Delay Tolerant Networks

This work addresses the integration of today\u27s infrastructure-based networks with infrastructure-less networks. The resulting Hybrid Routing System allows for communication over both network types and can help to overcome cost, communication, and overload problems. Mobility aspect resulting from infrastructure-less networks are analyzed and analytical models developed. For development and deployment of the Hybrid Routing System an overlay-based framework is presented

Hybrid routing in delay tolerant networks

This work addresses the integration of today\\u27s infrastructure-based networks with infrastructure-less networks. The resulting Hybrid Routing System allows for communication over both network types and can help to overcome cost, communication, and overload problems. Mobility aspect resulting from infrastructure-less networks are analyzed and analytical models developed. For development and deployment of the Hybrid Routing System an overlay-based framework is presented

End-to-End Resilience Mechanisms for Network Transport Protocols

The universal reliance on and hence the need for resilience in network communications has been well established. Current transport protocols are designed to provide fixed mechanisms for error remediation (if any), using techniques such as ARQ, and offer little or no adaptability to underlying network conditions, or to different sets of application requirements. The ubiquitous TCP transport protocol makes too many assumptions about underlying layers to provide resilient end-to-end service in all network scenarios, especially those which include significant heterogeneity. Additionally the properties of reliability, performability, availability, dependability, and survivability are not explicitly addressed in the design, so there is no support for resilience. This dissertation presents considerations which must be taken in designing new resilience mechanisms for future transport protocols to meet service requirements in the face of various attacks and challenges. The primary mechanisms addressed include diverse end-to-end paths, and multi-mode operation for changing network conditions

Mobility and connectivity in highway vehicular networks: a case study in Madrid

The performance of protocols and architectures for upcoming vehicular networks is commonly investigated by means of computer simulations, due to the excessive cost and complexity of large-scale experiments. Dependable and reproducible simulations are thus paramount to a proper evaluation of vehicular networking solutions. Yet, we lack today a reference dataset of vehicular mobility scenarios that are realistic, publicly available, heterogeneous, and that can be used for networking simulations straightaway. In this paper, we contribute to the endeavor of developing such a reference dataset, and present original synthetic traces that are generated from high-resolution real-world traffic counts. They describe road traffic in quasi-stationary state on three highways near Madrid, Spain, for different time-spans of several working days. To assess the potential impact of the traces on networking studies, we carry out a comprehensive analysis of the vehicular network topology they yield. Our results highlight the significant variability of the vehicular connectivity over time and space, and its invariant correlation with the vehicular density. We also underpin the dramatic influence of the communication range on the network fragmentation, availability, and stability, in all of the scenarios we consider.The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Unions Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n.630211 ReFleX. This research was also funded by Spanish MICINN through the ADAS-ROAD Project (TRA2013-48314-C3-1-R). Funding for D. Naboulsi was provided by a grant from Rhône-Alpes Region. This work was carried out while Marco Gramaglia was at CNR-IEIIT.Publicad

Software-Defined Networking Enabled Capacity Sharing in User Centric Networks

International audienceIn this paper, we discuss User Centric Networks (UCNs) as a way of, if not completely solving, considerably mitigating the problem of sharing limited network capacity and resources efficiently and fairly. UCNs are self-organizing networks where the end-user plays an active role in delivering networking functions such as providing Internet access to other users. We propose to leverage the recently proposed Software Defined Networking (SDN) paradigm to enable cooperation between wireless nodes and provide capacity sharing services in UCNs. Our SDN-based approach allows to extend coverage of existing network infrastructure (such as WiFi or 3GPP) to other end-users or ad hoc networks that would otherwise not be able to have access to network connectivity and services. Moreover, the proposed SDN-based architecture also takes into account current network load and conditions, and quality-of service (QoS) requirements. Another important feature of our framework is that security is an integral part of the architecture and protocols. We discuss the requirements for enabling capacity sharing services in the context of UCNs (e.g., resource discovery, node admission control, cooperation incentives, QoS, security, etc) and how SDN can aid in enabling such services. The paper also describes the proposed SDN-enabled capacity sharing framework for UCNs

Resource management in future mobile networks: from millimetre-wave backhauls to airborne access networks

The next generation of mobile networks will connect vast numbers of devices and support services with diverse requirements. Enabling technologies such as millimetre-wave (mm-wave) backhauling and network slicing allow for increased wireless capacities and logical partitioning of physical deployments, yet introduce a number of challenges. These include among others the precise and rapid allocation of network resources among applications, elucidating the interactions between new mobile networking technology and widely used protocols, and the agile control of mobile infrastructure, to provide users with reliable wireless connectivity in extreme scenarios. This thesis presents several original contributions that address these challenges. In particular, I will first describe the design and evaluation of an airtime allocation and scheduling mechanism devised specifically for mm-wave backhauls, explicitly addressing inter-flow fairness and capturing the unique characteristics of mm-wave communications. Simulation results will demonstrate 5x throughput gains and a 5-fold improvement in fairness over recent mm-wave scheduling solutions. Second, I will introduce a utility optimisation framework targeting virtually sliced mm-wave backhauls that are shared by a number of applications with distinct requirements. Based on this framework, I will present a deep learning solution that can be trained within minutes, following which it computes rate allocations that match those obtained with state-of-the-art global optimisation algorithms. The proposed solution outperforms a baseline greedy approach by up to 62%, in terms of network utility, while running orders of magnitude faster. Third, the thesis investigates the behaviour of the Transport Control Protocol (TCP) in Long-Term Evolution (LTE) networks and discusses the implications of employing Radio Link Control (RLC) acknowledgements under different link qualities, on the performance of transport protocols. Fourth, I will introduce a reinforcement learning approach to optimising the performance of airborne cellular networks serving users in emergency settings, demonstrating rapid convergence (approx. 2.5 hours on a desktop machine) and a 5dB improvement of the median Signal-to-Noise-plus-Interference-Ratio (SINR) perceived by users, over a heuristic based benchmark solution. Finally, the thesis discusses promising future research directions that follow from the results obtained throughout this PhD project