Toward an RSU-unavailable lightweight certificateless key agreement scheme for VANETs

Vehicle ad-hoc networks have developed rapidly these years, whose security and privacy issues are always concerned widely. In spite of a remarkable research on their security solutions, but in which there still lacks considerations on how to secure vehicle-to-vehicle communications, particularly when infrastructure is unavailable. In this paper, we propose a lightweight certificateless and one-round key agreement scheme without pairing, and further prove the security of the proposed scheme in the random oracle model. The proposed scheme is expected to not only resist known attacks with less computation cost, but also as an efficient way to relieve the workload of vehicle-to-vehicle authentication, especially in no available infrastructure circumstance. A comprehensive evaluation, including security analysis, efficiency analysis and simulation evaluation, is presented to confirm the security and feasibility of the proposed scheme

Ein dienstgütebasiertes Routingprotokoll für ein selbstorganisiertes Kommunikationsnetz

Mobile Ad-hoc Networks (MANETs) are characterized by two dimensions namely, anywhere and anytime. The freely moving participating nodes can form an ad hoc network anywhere, and the mobile nodes can join or leave the network anytime. A particular mobile node in a MANET can communicate with all the other nodes using the multihop communication. Thus, MANETs offer a vast range of applications in various domains like entertainment, military, emergency, etc. However, the implementation of real-time applications like voice/video calling that demands stringent quality requirements over MANETs is a major challenge. This challenge arises due to the unplanned and dynamic nature of MANETs, due to the unreliability of wireless links, due to the scarcity of resources like battery, bandwidth, processing power, due to the large-scale nature of MANETs, etc. This issue can be addressed at the network layer or the routing protocol, which establishes multiple routes from source to destination and adapts to the dynamicity of MANETs without compromising on the quality requirements. The primary goal of this work is the investigation and development of such a routing algorithm that supports real-time applications over MANETs. For adaptive multipath routing, we studied Ant Colony Optimization (ACO) algorithms originate from the fields of Swarm Intelligence (SI) while Quality of Service (QoS) computation is carried out by cleverly utilizing the monitoring feature of the Simple Network Management Protocol (SNMP). So, combining these two mechanisms we propose a powerful adaptive multipath QoS-aware Routing protocol based on ACO (QoRA). We discuss and investigate the internal working of QoRA and perform detailed simulation studies in the network simulator ns-3. Finally, we discuss the implementation of QoRA routing algorithms in a real world testbed.Mobile Ad-hoc-Netze (MANETs) ermöglichen eine Kommunikation überall zu jedem Zeitpunkt. Frei sich bewegende Knoten können überall ein solches Netz bilden, wobei die Teilnehmer zu jeder Zeit dem Netz beitreten oder es wieder verlassen können. Ein teilnehmender Knoten in einem MANET kommuniziert mit allen anderen über Multi-Hop-Kommunikation. So ermöglicht ein MANET viele unterschiedliche Anwendungen aus verschiedenen Domänen wie beispielsweise Unterhaltungskommunikation, Notfallkommunikation oder Einsatzkommunikation. Allerdings benötigen Echtzeitanwendungen wie Telefonie oder Videokommunikation eine stringente Kommunikationsdienstgüte, was für MANETs eine große Herausforderung darstellt. Diese Herausforderung hat viele Gründe: das dynamische und unvorhersehbare Verhalten der Knoten im MANET, die Unzuverlässigkeit der drahtlosen Kommunikation, die Beschränkung der zur Verfügung stehenden Kommunikationsressourcen (wie Batterielaufzeit, Bandbreite oder Prozessorleistung), die relativ große Abdeckung durch ein MANET. Die Herausforderung kann in der Vermittlungsschicht durch ein spezielles Routingprotokoll gelöst werden, das mehrere gleichzeitige Pfade von der Quelle zum Ziel verwendet, sodass die Dynamik in einem MANET Berücksichtigung findet ohne dass die Dienstgüte kompromittiert werden muss. Das vorrangige Ziel dieser Arbeit ist die Erforschung und Entwicklung eines solchen Routingverfahrens, das Echtzeitanwendungen in einem MANET unterstützt. Für das adaptive Mehrwegerouting wurde ein Ameisenalgorithmus (Ant Colony Optimization, ACO) angewendet, der das Prinzip der Schwarmintelligenz ausnutzt. Die Bestimmung der aktuell möglichen Kommunikationsdienstgüte erfolgt über die Informationen, die das Netzmanagementprotokoll Simple Network Management Protocol SNMP standardmäßig zur Verfügung stellt. Durch die Kombination dieser beiden Ansätze wurde das adaptive Mehrwegeroutingprotokoll "QoS-aware Routing Protocol based on ACO" (QoRA) vorgeschlagen. In der vorliegenden Dissertation werden das Konzept von QoRA vorgestellt und die interne Funktionsweise erläutert. Anhand umfangreicher Simulationen auf Basis des Simulationswerkzeug ns-3 werden die Vorteile des Verfahrens nachgewiesen. Den Abschluss bildet die Diskussion einer Implementierung von QoRA in einer realen Testumgebung

Enhancing quality-of-service conditions using a cross-layer paradigm for ad-hoc vehicular communication

The Internet of Vehicles (IoVs) is an emerging paradigm aiming to introduce a plethora of innovative applications and services that impose a certain quality of service (QoS) requirements. The IoV mainly relies on vehicular ad-hoc networks (VANETs) for autonomous inter-vehicle communication and road-traffic safety management. With the ever-increasing demand to design new and emerging applications for VANETs, one challenge that continues to stand out is the provision of acceptable QoS requirements to particular user applications. Most existing solutions to this challenge rely on a single layer of the protocol stack. This paper presents a cross-layer decision-based routing protocol that necessitates choosing the best multi-hop path for packet delivery to meet acceptable QoS requirements. The proposed protocol acquires the information about the channel rate from the physical layer and incorporates this information in decision making, while directing traffic at the network layer level. Key performance metrics for the system design are analyzed using extensive experimental simulation scenarios. In addition, three data rate variant solutions are proposed to cater for various application-specific requirements in highways and urban environments. © 2013 IEEE

Scalable Network Design and Management with Decentralized Software-defined Networking

Network softwarization is among the most significant innovations of computer networks in the last few decades. The lack of uniform and programmable interfaces for network management led to the design of OpenFlow protocol for the university campuses and enterprise networks. This breakthrough coupled with other similar efforts led to an emergence of two complementary but independent paradigms called software-defined networking (SDN) and network function virtualization (NFV). As of this writing, these paradigms are becoming the de-facto norms of wired and wireless networks alike. This dissertation mainly addresses the scalability aspect of SDN for multiple network types. Although centralized control and separation of control and data planes play a pivotal role for ease of network management, these concepts bring in many challenges as well. Scalability is among the most crucial challenges due to the unprecedented growth of computer networks in the past few years. Therefore, we strive to grapple with this problem in diverse networking scenarios and propose novel solutions by harnessing capabilities provided by SDN and other related technologies. Specifically, we present the techniques to deploy SDN at the Internet scale and to extend the concepts of softwarization for mobile access networks and vehicular networks. Multiple optimizations are employed to mitigate latency and other overheads that contribute to achieve performance gains. Additionally, by taking care of sparse connectivity and high mobility, the intrinsic constraints of centralization for wireless ad-hoc networks are addressed in a systematic manner. The state-of-the-art virtualization techniques are coupled with cloud computing methods to exploit the potential of softwarization in general and SDN in particular. Finally, by tapping into the capabilities of machine learning techniques, an SDN-based solution is proposed that inches closer towards the longstanding goal of self-driving networks. Extensive experiments performed on a large-scale testbed corroborates effectiveness of our approaches

Improving Resilience of Communication in Information Dissemination for Time-Critical Applications

Severe weather impacts life and in this dire condition, people rely on communication, to organize relief and stay in touch with their loved ones. In such situations, cellular network infrastructure\footnote{We refer to cellular network infrastructure as infrastructure for the entirety of this document} might be affected due to power outage, link failures, etc. This urges us to look at Ad-hoc mode of communication, to offload major traffic partially or fully from the infrastructure, depending on the status of it. We look into threefold approach, ranging from the case where the infrastructure is completely unavailable, to where it has been replaced by make shift low capacity mobile cellular base station. First, we look into communication without infrastructure and timely, dissemination of weather alerts specific to geographical areas. We look into the specific case of floods as they affect significant number of people. Due to the nature of the problem we can utilize the properties of Information Centric Networking (ICN) in this context, namely: i) Flexibility and high failure resistance: Any node in the network that has the information can satisfy the query ii) Robust: Only sensor and car need to communicate iii) Fine grained geo-location specific information dissemination. We analyze how message forwarding using ICN on top of Ad hoc network, approach compares to the one based on infrastructure, that is less resilient in the case of disaster. In addition, we compare the performance of different message forwarding strategies in VANETs (Vehicular Adhoc Networks) using ICN. Our results show that ICN strategy outperforms the infrastructure-based approach as it is 100 times faster for 63\% of total messages delivered. Then we look into the case where we have the cellular network infrastructure, but it is being pressured due to rapid increase in volume of network traffic (as seen during a major event) or it has been replaced by low capacity mobile tower. In this case we look at offloading as much traffic as possible from the infrastructure to device-to-device communication. However, the host-oriented model of the TCP/IP-based Internet poses challenges to this communication pattern. A scheme that uses an ICN model to fetch content from nearby peers, increases the resiliency of the network in cases of outages and disasters. We collected content popularity statistics from social media to create a content request pattern and evaluate our approach through the simulation of realistic urban scenarios. Additionally, we analyze the scenario of large crowds in sports venues. Our simulation results show that we can offload traffic from the backhaul network by up to 51.7\%, suggesting an advantageous path to support the surge in traffic while keeping complexity and cost for the network operator at manageable levels. Finally, we look at adaptive bit-rate streaming (ABR) streaming, which has contributed significantly to the reduction of video playout stalling, mainly in highly variable bandwidth conditions. ABR clients continue to suffer from the variation of bit rate qualities over the duration of a streaming session. Similar to stalling, these variations in bit rate quality have a negative impact on the users’ Quality of Experience (QoE). We use a trace from a large-scale CDN to show that such quality changes occur in a significant amount of streaming sessions and investigate an ABR video segment retransmission approach to reduce the number of such quality changes. As the new HTTP/2 standard is becoming increasingly popular, we also see an increase in the usage of HTTP/2 as an alternative protocol for the transmission of web traffic including video streaming. Using various network conditions, we conduct a systematic comparison of existing transport layer approaches for HTTP/2 that is best suited for ABR segment retransmissions. Since it is well known that both protocols provide a series of improvements over HTTP/1.1, we perform experiments both in controlled environments and over transcontinental links in the Internet and find that these benefits also “trickle up” into the application layer when it comes to ABR video streaming where HTTP/2 retransmissions can significantly improve the average quality bitrate while simultaneously minimizing bit rate variations over the duration of a streaming session. Taking inspiration from the first two approaches, we take into account the resiliency of a multi-path approach and further look at a multi-path and multi-stream approach to ABR streaming and demonstrate that losses on one path have very little impact on the other from the same multi-path connection and this increases throughput and resiliency of communication

Service Competition and Data-Centric Protocols for Internet Access

The Internet evolved in many aspects, from the application to the physical layers. However, the evolution of the Internet access technologies, most visible in dense urban scenarios, is not easily noticeable in sparsely populated and rural areas. In the United States, for example, the FCC identified that 50% of the census blocks have access to up to two broadband providers; however, these providers do not necessarily compete. Additionally, due to the methodology of the study, there is evidence that the number of actual customers without broadband access is higher since the FCC considers the entire block to have broadband if any customer in a block has broadband. Moreover, the average downstream connection bandwidth in the United States is 18.7 Mbps, according to the Akamai State of the Internet report, which places the US in the 10th position in the global rank. It’s worth noting that modern applications such as Ultra High Definition (UHD) video streaming requires a bandwidth of at least 25 Mbps. Newer applications such as virtual reality streaming require at least a 50 Mbps bandwidth. Additionally, urban scenarios are dominated by monopolistic and duopolistic markets, whereby network providers have little incentives to offer innovative services. In this work, we propose an open access network infrastructure along with a novel Internet architecture that allows dynamic economic relationships between users and providers through a marketplace of network services. These economic relationships have a finer granularity than today’s coarse and lengthy contracts, allowing higher competition and promoting innovation in the access market. We develop an agent-based simulator to evaluate our proposed network model and its various competition scenarios. Our simulations show that competition greatly benefits users and applications, creating the necessary incentives for providers to innovate while also benefiting consumers. The trend that resulted in sparsely populated areas lagging of the latest innovations in the access networks is also observed in wireless access networks, where the investments are focused on densely populated areas. Moreover, the rapidly increasing number of mobile devices coupled with the increasingly bandwidth demanding applications are posing a significant challenge to cellular network operators that have to increase OPEX/CAPEX and deal with higher complexity in their networks. The advances in the access technologies that brought higher speeds and lower latency also reduced the area of coverage of cellular base stations. To cope with the increase in traffic, cellular network operators have been deploying more base stations. In addition, cellular providers have adopted “all-you-can-use” price models, which led users to ramp-up their usage, further worsening congestion in the network. To address this issue, we propose a scheme that uses Device-to-Device (D2D) communication along with Information-Centric Networking (ICN) to offload traffic from cellular base stations. Then, we build on this scheme and propose a cross-layer assisted forwarding strategy to enhance communication in the MANET. In D2D communication, users can retrieve content directly from their nearby peers. However, this type of communication poses challenges to the current connection-oriented communication model, as devices can move in and out of the communication range at any time, constantly changing routing state, and nodes are subject to hidden and exposed terminal problems. ICN addresses some of these issues with inherent support for transparent caching and named content retrieval, making the network more resilient to disconnections. Our proposed scheme can offload up to 51.7% of the contents from the backhaul cellular infrastructure when requesting the content from nearby peers first. Finally, we combine the concepts of the marketplace, D2D communication, and ICN to propose a platform for decentralized and opportunistic communication that uses COTS radios to relay packets, extending the reach of the Internet to sparsely populated areas with low cost and without the lengthy contracts from commercial network providers. Our platform can potentially link the remaining part of the population that is not currently connected to the Internet