Emergency message dissemination schemes based on congestion avoidance in VANET and vehicular FoG computing

With the rapid growth in connected vehicles, FoG-assisted vehicular ad hoc network (VANET) is an emerging and novel field of research. For information sharing, a number of messages are exchanged in various applications, including traffic monitoring and area-specific live weather and social aspects monitoring. It is quite challenging where vehicles' speed, direction, and density of neighbors on the move are not consistent. In this scenario, congestion avoidance is also quite challenging to avoid communication loss during busy hours or in emergency cases. This paper presents emergency message dissemination schemes that are based on congestion avoidance scenario in VANET and vehicular FoG computing. In the similar vein, FoG-assisted VANET architecture is explored that can efficiently manage the message congestion scenarios. We present a taxonomy of schemes that address message congestion avoidance. Next, we have included a discussion about comparison of congestion avoidance schemes to highlight the strengths and weaknesses. We have also identified that FoG servers help to reduce the accessibility delays and congestion as compared to directly approaching cloud for all requests in linkage with big data repositories. For the dependable applicability of FoG in VANET, we have identified a number of open research challenges. © 2013 IEEE

Broadcasting Protocol for Effective Data Dissemination in Vehicular Ad Hoc Networks

VANET topology is very dynamic due to frequent movements of the nodes. Using beacon information connected dominated set are formed and nodes further enhanced with neighbor elimination scheme. With acknowledgement the inter section issues are solve. A modified Broadcast Conquest and Delay De-synchronization mechanism address the broadcasting storm issues. Although data dissemination is possible in all direction, the performance of data dissemination in the opposite direction is investigated and compared against the existing protocols

Wireless Sensor Data Transport, Aggregation and Security

abstract: Wireless sensor networks (WSN) and the communication and the security therein have been gaining further prominence in the tech-industry recently, with the emergence of the so called Internet of Things (IoT). The steps from acquiring data and making a reactive decision base on the acquired sensor measurements are complex and requires careful execution of several steps. In many of these steps there are still technological gaps to fill that are due to the fact that several primitives that are desirable in a sensor network environment are bolt on the networks as application layer functionalities, rather than built in them. For several important functionalities that are at the core of IoT architectures we have developed a solution that is analyzed and discussed in the following chapters. The chain of steps from the acquisition of sensor samples until these samples reach a control center or the cloud where the data analytics are performed, starts with the acquisition of the sensor measurements at the correct time and, importantly, synchronously among all sensors deployed. This synchronization has to be network wide, including both the wired core network as well as the wireless edge devices. This thesis studies a decentralized and lightweight solution to synchronize and schedule IoT devices over wireless and wired networks adaptively, with very simple local signaling. Furthermore, measurement results have to be transported and aggregated over the same interface, requiring clever coordination among all nodes, as network resources are shared, keeping scalability and fail-safe operation in mind. Furthermore ensuring the integrity of measurements is a complicated task. On the one hand Cryptography can shield the network from outside attackers and therefore is the first step to take, but due to the volume of sensors must rely on an automated key distribution mechanism. On the other hand cryptography does not protect against exposed keys or inside attackers. One however can exploit statistical properties to detect and identify nodes that send false information and exclude these attacker nodes from the network to avoid data manipulation. Furthermore, if data is supplied by a third party, one can apply automated trust metric for each individual data source to define which data to accept and consider for mentioned statistical tests in the first place. Monitoring the cyber and physical activities of an IoT infrastructure in concert is another topic that is investigated in this thesis.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Design of an adaptive congestion control protocol for reliable vehicle safety communication

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MAC/PHY Cross-Layer Design for Improved Vehicular Safety Messaging Reliability and Simulation Environment Design

In vehicle-to-vehicle safety messaging, periodic safety messages can be used for safety applications. These applications require low latency and high probability of reception, however there can be a problem with unsuccessful reception due to collision of these safety messages when there are sufficiently large amount of vehicles and/or repetitions. Literature proposes repetition based broadcasting to increase reception probability, while decreasing average reception delay; however this increases the probability of packet collision and overall network traffic. In this thesis, we introduce a new cross-layer design, which allows for collision correction of safety message repetitions for further improving probability of reception. We describe our design as well as simulation using various repetition schemes under different packet error rates and compare our cross-layer collision correction method with non-collision correcting performance. Once implemented, this new approach can substantially improve the reception likelihood of safety messages, without loss of latency, and potentially make active vehicle safety applications more responsive

Cross-Layer Treatment of Mobility for Mobile Ad Hoc Networks

The current era of mobile communication is passing through the days of rapidly changing technologies. Such an evolving promising technology is mobile ad hoc networks (MANETs). The communications in ad hoc networks are adversely affected by the link failures in the network layer, and by the hidden station, mobile hidden station, neighborhood capture and asymmetric radio link problems in the MAC layer. All the problems are highly affected by mobility of the stations. If the degree of mobility of any station in a route increases, the route life time decreases. That causes frequent link failures, and results packet retransmissions, additional latency and packet loss. An algorithm to include mobility in a routing protocol to reduce packet losses in a MANET is proposed in this thesis. The proposed algorithm estimates the number of packets that can traverse through the route before it breaks because of mobility. The algorithm is implemented in dynamic source routing protocol, and simulated in Network Simulator-2. The MHS problem arises if a station is hidden due to mobility. Asymmetric/unequal radio links in can occur in MANETs/VANETs for many reasons such as hardware limitations, power saving protocols, shadowing effects, dynamic spectrum managements. A MAC protocol named extended reservation Aloha (ERA) is proposed which partially solves these problems. Then, using the concept of ERA, another MAC protocol named extended sliding frame reservation Aloha (ESFRA), which addresses all the above mentioned MAC problems, is proposed in this thesis. As safety critical information dissemination in DSRC/WAVE systems requires reliability and robustness, a network-MAC cross-layer information dissemination protocol is proposed in this thesis to address those issues. Although the layered architecture is still a good candidate for any design of wireless networks, the researchers are looking for some optimizations by interaction between neighbor layers which is called cross-layer design. So I proposed a network-MAC cross-layer algorithm, cross-layer extended sliding frame reservation Aloha (CESFRA), which solves mobility related problems, confirms low and deterministic end-to-end delay, and is robust and reliable in safety critical information dissemination up to 3rd hop. Discrete time Markov chain (DTMC) and OMNeT++ are used for all the MAC layer analyses

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Capturing the impact of external interference on HPC application performance

HPC applications are large software packages with high computation and storage requirements. To meet these requirements, the architectures of supercomputers are continuously evolving and their capabilities are continuously increasing. Present-day supercomputers have achieved petaflops of computational power by utilizing thousands to millions of compute cores, connected through specialized communication networks, and are equipped with petabytes of storage using a centralized I/O subsystem. While fulfilling the high resource demands of HPC applications, such a design also entails its own challenges. Applications running on these systems own the computation resources exclusively, but share the communication interconnect and the I/O subsystem with other concurrently running applications. Simultaneous access to these shared resources causes contention and inter-application interference, leading to degraded application performance. Inter-application interference is one of the sources of run-to-run variation. While other sources of variation, such as operating system jitter, have been investigated before, this doctoral thesis specifically focuses on inter-application interference and studies it from the perspective of an application. Variation in execution time not only causes uncertainty and affects user expectations (especially during performance analysis), but also causes suboptimal usage of HPC resources. Therefore, this thesis aims to evaluate inter-application interference, establish trends among applications under contention, and approximate the impact of external influences on the runtime of an application. To this end, this thesis first presents a method to correlate the performance of applications running side-by-side. The method divides the runtime of a system into globally synchronized, fine-grained time slices for which application performance data is recorded separately. The evaluation of the method demonstrates that correlating application performance data can identify inter-application interference. The thesis further uses the method to study I/O interference and shows that file access patterns are a significant factor in determining the interference potential of an application. This thesis also presents a technique to estimate the impact of external influences on an application run. The technique introduces the concept of intrinsic performance characteristics to cluster similar application execution segments. Anomalies in the cluster are the result of external interference. An evaluation with several benchmarks shows high accuracy in estimating the impact of interference from a single application run. The contributions of this thesis will help establish interference trends and devise interference mitigation techniques. Similarly, estimating the impact of external interference will restore user expectations and help performance analysts separate application performance from external influence

Proceedings of the Third International Mobile Satellite Conference (IMSC 1993)

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial cellular communications services. While the first and second International Mobile Satellite Conferences (IMSC) mostly concentrated on technical advances, this Third IMSC also focuses on the increasing worldwide commercial activities in Mobile Satellite Services. Because of the large service areas provided by such systems, it is important to consider political and regulatory issues in addition to technical and user requirements issues. Topics covered include: the direct broadcast of audio programming from satellites; spacecraft technology; regulatory and policy considerations; advanced system concepts and analysis; propagation; and user requirements and applications