The vehicle-to-vehicle (V2V) propagation channel has significant implications on the design and performance of novel communication protocols for vehicular ad hoc networks (VANETs). Extensive research efforts have been made to develop V2V channel models to be implemented in advanced VANET system simulators for performance evaluation. The impact of shadowing caused by other vehicles has, however, largely been neglected in most of the models, as well as in the system simulations. In this paper we present a shadow fading model targeting system simulations based on real measurements performed in urban and highway scenarios. The measurement data is separated into three categories, line-of-sight (LOS), obstructed line-of-sight (OLOS) by vehicles, and non-line-of-sight due to buildings, with the help of video information recorded during the measurements. It is observed that vehicles obstructing the LOS induce an additional average attenuation of about 10 dB in the received signal power. An approach to incorporate the LOS/OLOS model into existing VANET simulators is also provided. Finally, system level VANET simulation results are presented, showing the difference between the LOS/OLOS model and a channel model based on Nakagami-m fading.

The accelerated move toward the adoption of the Industrial Internet-of-Things (IIoT) paradigm has resulted in numerous shortcomings as far as security is concerned. One of the IIoT affecting critical security threats is what is termed as the false data injection (FDI) attack. The FDI attacks aim to mislead the industrial platforms by falsifying their sensor measurements. FDI attacks have successfully overcome the classical threat detection approaches. In this article, we present a novel method of FDI attack detection using autoencoders (AEs). We exploit the sensor data correlation in time and space, which in turn can help identify the falsified data. Moreover, the falsified data are cleaned using the denoising AEs (DAEs). Performance evaluation proves the success of our technique in detecting FDI attacks. It also significantly outperforms a support vector machine (SVM)-based approach used for the same purpose. The DAE data cleaning algorithm is also shown to be very effective in recovering clean data from corrupted (attacked) data. © 2014 IEEE.

In the field of structural operational semantics (SOS), there have been several proposals both for syntactic rule formats guaranteeing the validity of algebraic laws, and for algorithms for automatically generating ground-complete axiomatizations. However, there has been no synergy between these two types of results. This paper takes the first steps in marrying these two areas of research in the meta-theory of SOS and shows that taking algebraic laws into account in the mechanical generation of axiomatizations results in simpler axiomatizations. The proposed theory is applied to a paradigmatic example from the literature, showing that, in this case, the generated axiomatization coincides with a classic hand-crafted one. © 2013 Springer-Verlag Berlin Heidelberg.

We report on a tool prototype for model-based testing of cyber-physical systems. Our starting point is a hybrid-system model specified in a domain-specific language called Acumen. Our prototype tool is implemented in Matlab and covers three stages of model-based testing, namely, test-case generation, test-case execution, and conformance analysis. We have applied our implementation to a number of typical examples of cyber-physical systems in order to analyze its applicability. In this paper, we report on the result of applying the prototype tool on a DC-DC boost converter. © Springer International Publishing Switzerland 2015

Cyber-physical systems (CPSs) are the result of the integration of connected computer systems with the physical world. They feature complex interactions that go beyond traditional communication schemes and protocols in computer systems. One distinguished feature of such complex interactions is the tight coupling between discrete and continuous interactions, captured by hybrid system models.

Due to the complexity of CPSs, providing rigorous and model-based analysis methods and tools for verifying correctness of such systems is of the utmost importance. Model-based testing (MBT) is one such verification technique that can be used for checking the conformance of an implementation of a system to its specification (model).

In this chapter, we first review the main concepts and techniques in MBT. Subsequently, we review the most common modeling formalisms for CPSs, with focus on hybrid system models. Subsequently, we provide a brief overview of conformance relations and conformance testing techniques for CPSs. © 2017 Elsevier Inc. All rights reserved.

Application specific architectures are highly desirable in embedded parallel computing systems at the same time as designers strive for using one embedded parallel computing platform for several applications. If this can be achieved, the cost can be decreased in comparison to using several different embedded parallel computing systems. This paper presents a novel approach of running several high-performance applications concurrently on one single parallel computing system. By using a reconfigurable backplane interconnection system, the applications can be run efficiently with high network flexibility since the interconnect network can be adapted to fit the application that is being processed for the moment. More precisely, this paper investigates how the space time adaptive processing (STAP) radar algorithm and the stripmap synthetic aperture radar (SAR) algorithm can be mapped on a multi-cluster processing system with a reconfigurable optical interconnection system realized by a micro-optical-electrical mechanical system (MOEMS) crossbars. The paper describes the reconfigurable platform, the two algorithms and how they individually can be mapped on the targeted multiprocessor system. It is also described how these two applications can be mapped simultaneously on the optical reconfigurable platform. Implications and requirements on communication bandwidth and processor performance in different critical points of the two applications are presented. The results of the analysis show that an implementation is feasible with today's MOEMS technology, and that the two applications can be successfully run in a time-sharing scheme, both at the processing side and at the access for interconnection bandwidth.

Bluetooth Low Energy (BLE) is one of the most important technologies that feed the growing field of Internet of Things and Wireless Sensor Networks. Due to its flexibility and unique low power-consumption, an increasing number of industrial devices, household appliances and wearables are being designed using it. However, the real-time demands of these networks such as timing and Quality of Service are not fully covered by the protocol itself. To help improve and offer some control over these characteristics, this paper presents a time slot transmission scheme with packet prioritization. It is based on the division and allocation of the connection interval to two types of messages: real-time and ordinary. The goal is to offer the lowest packet loss and time guarantees for real-time messages, while providing acceptable throughput for ordinary ones. Since the probability of a BLE connection to close increases with the number of packets sent through it, the position where a real-time packet is being sent as well as the number of ordinary messages in a connection represent key factors. The use of the first and last slot for real-time packets with ordinary flow restricted to the space between them decreases the transmission delay uncertainty and allows probability tuning based on the number of ordinary messages. Simulations were performed using the proposed scheme and a reduction of more than 100 times in the delay variance was observed for real-time transmissions. Regarding reliability, around 5% of the packets were lost for a bit error rate of 10⁻³. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

We present a survey of the recent research efforts in integrating model learning with model-based testing. We distinguished two strands of work in this domain, namely test-based learning (also called test-based modeling) and learning-based testing. We classify the results in terms of their underlying models, their test purpose and techniques, and their target domains. © Springer International Publishing AG

The three dimensional structure tensor algorithm (3D-STA) is often used in image processing applications to compute the optical flow or to detect local 3D structures and their directions. This algorithm is computationally expensive due to many computations that are required to calculate the gradient, the tensor, and to smooth every pixel of the image frames. Therefore, it is important to parallelize the implementation to achieve high performance. In this paper we present two parallel implementations of 3D-STA; namely moderately parallelized and highly parallelized implementation, on a massively parallel reconfigurable array. Finally, we evaluate the performance of the generated code and results are compared with another optical flow implementation. The throughput achieved by the moderately parallelized implementation is approximately half of the throughput of the Optical flow implementation, whereas the highly parallelized implementation results in a 2x gain in throughput as compared to the optical flow implementation. © 2012 IEEE.

Chattering is a fundamental phenomenon that is unique to hybrid systems, due to the complex interaction between discrete dynamics (in the form of discrete transitions) and continuous dynamics (in the form of time). In practice, simulating chattering hybrid systems is challenging in that simulation effectively halts near the chattering time point, as an infinite number of discrete transitions would need to be simulated. In this paper, formal conditions are provided for when the simulated models of hybrid systems display chattering behavior, and methods are proposed for avoiding chattering “on the fly” in runtime. We utilize dynamical behavior analysis to derive conditions for detecting chattering without enumeration of modes. We also present a new iterative algorithm to allow for solutions to be carried past the chattering point, and we show by a prototypical implementation how to generate the equivalent chattering-free dynamics internally by the simulator in the main simulation loop. The concepts are illustrated with examples throughout the paper. © 2016 IEEE.

A content addressable memory (CAM) is a type of memory that implements a parallel search engine at its core. A CAM takes as an input a value and outputs the address where this value is stored in case of a match. CAMs are used in a wide range of applications including networking, cashing, neuromorphic associative memories, multimedia, and data analytics. Here, we introduce a novel opto-electronic CAM (OE-CAM) utilizing the integrated silicon photonic platform. In our approach, we explore the performance of an experimental OE-CAM and verify the efficiency of the device at 25 Gbit/s while maintaining the bit integrity under noise conditions. We show that OE-CAM enables a) two orders of magnitude faster search functionality resulting in b) a five orders of magnitude lower power-delay-product compared to CAMs implementations based on other emerging technologies. This remarkable performance potential is achieved by utilizing i) a high parallelism of wavelength-division-multiplexing in the optical domain, combined with ii) 10's of GHz-fast opto-electronic components, packaged in iii) integrated photonics for 10-100's ps-short communication delays. We further verify the upper optical input power limit of this OE-CAM to be given by parasitic nonlinearities inside the silicon waveguides, and the minimal detectable optical power at the back-end photoreceiver's responsivity given channel noise. Such energy-efficient and short-delay OE-CAMs could become a key component of functional photonic-augmented ASICS, co-processors, or smart sensors. © IEEE

This work presents the temporal analysis for a distributed differential control system for a mobile robot deployed on a wireless network using the SunSPOT platform. The system is programmed in Java and each of its part is executed in a distinct processor which cooperates via a wireless network. The communication between the network nodes is made by remote procedure calls, which are implemented by a minimum version of the Java RMI (mRMI), presented in this work. Simulation results are compared to experimental data acquired by the deployment of the system on real devices, the SunSPOTs. The comparisons reveal that the distributed solution presents fairly good results besides the inserted errors due to the wireless communication. © 2011 IEEE.

Vehicle-to-everything (V2X) communications allow a vehicle to interact with other vehicles and with communication parties in its vicinity (e.g., road-side units, pedestrian users, etc.) with the primary goal of making the driving and traveling experience safer, smarter and more comfortable. A wide set of V2X-tailored specifications have been identified by the Third Generation Partnership Project (3GPP) with focus on the design of architecture enhancements and a flexible air interface to ensure ultra-low latency, highly reliable and high-throughput connectivity as the ultimate aim. This paper discusses the potential of leveraging Information-Centric Networking (ICN) principles in the 3GPP architecture for V2X communications. We consider Named Data Networking (NDN) as reference ICN architecture and elaborate on the specific design aspects, required changes and enhancements in the 3GPP V2X architecture to enable NDN-based data exchange as an alternative/complementary solution to traditional IP networking, which barely matches the dynamics of vehicular environments. Results are provided to showcase the performance improvements of the NDN-based proposal in disseminating content requests over the cellular network against a traditional networking solution. © 2019 by the authors.

Due to the end of Moore’s law and Dennard scaling, we are entering a new era of processors. Computing systems are increasingly facing power and performance challenges due to both device- and circuit-related challenges with resistive and capacitive charging. Non-von Neumann architectures are needed to support future computations through innovative post-Moore’s law architectures. To enable these emerging architectures with high-performance and at ultra-low power, both parallel computation and inter-node communication on-the-chip can be supported using photons. To this end, we introduce ROC, a reconfigurable optical computer that can solve partial differential equations (PDEs). PDE solvers form the basis for many traditional simulation problems in science and engineering that are currently performed on supercomputers. Instead of solving problems iteratively, the proposed engine uses a resistive mesh architecture to solve a PDE in a single iteration (one-shot). Instead of using actual electrical circuits, the physical underlying hardware emulates such structures using a silicon-photonics mesh that splits light into separate pathways, allowing it to add or subtract optical power analogous to programmable resistors. The time to obtain the PDE solution then only depends on the time-of-flight of a photon through the programmed mesh, which can be on the order of 10’s of picoseconds given the millimeter-compact integrated photonic circuit. Numerically validated experimental results show that, over multiple configurations, ROC can achieve several orders of magnitude improvement over state-of-the-art GPUs when speed, power, and size are taken into account. Further, it comes within approximately 90% precision of current numerical solvers. As such, ROC can be a viable reconfigurable, approximate computer with the potential for more precise results when replacing silicon-photonics building blocks with nanoscale photonic lumped-elements. © 2020 ACM

Cooperative Intelligent Transport Systems (C-ITS) enable actors in the transport systems to interact and collaborate by exchanging information via wireless communication networks. There are several challenges to overcome before they can be implemented and deployed on public roads. Among the most important challenges are testing and evaluation in order to ensure the safety of C-ITS applications.

This thesis focuses on testing and evaluation of C-ITS applications with regard to their safety using simulation. The main focus is on one C-ITS application, namely platooning, that is enabled by the Cooperative Adaptive Cruise Control (CACC) function. Therefore, this thesis considers two main topics: i) what should be modelled and simulated for testing and evaluation of C-ITS applications? and ii) how should CACC functions be evaluated in order to ensure safety?

When C-ITS applications are deployed, we can expect traffic situations which consist of vehicles with different capabilities, in terms of automation and connectivity. We propose that involving human drivers in testing and evaluation is important in such mixed traffic situations. Considering important aspects of C-ITS including human drivers, we propose a simulation framework, which combines driving-, network-, and traffic simulators. The simulation framework has been validated by demonstrating several use cases in the scope of platooning. In particular, it is used to demonstrate and analyse the safety of platooning applications in cut-in situations, where a vehicle driven by a human driver cuts in between vehicles in platoon. To assess the situations, time-to-collision (TTC) and its extensions are used as safety indicators in the analyses.

The simulation framework permits future C-ITS research in other fields such as human factors by involving human drivers in a C-ITS context. Results from the safety analyses show that cut-in situations are not always hazardous, and two factors that are the most highly correlated to the collisions are relative speed and distance between vehicles at the moment of cutting in. Moreover, we suggest that to solely rely on CACC functions is not sufficient to handle cut-in situations. Therefore, guidelines and standards are required to address these situations properly.

Future vehicles are expected to be equipped with wireless communication tech- nology, that enables them to be “connected” to each others and road infras- tructures. Complementing current autonomous vehicles and automated driving systems, the wireless communication allows the vehicles to interact, cooperate, and be aware of its surroundings beyond their own sensors’ range. Such sys- tems are often referred to as Cooperative Intelligent Transport Systems (C-ITS), which aims to provide extra safety, efficiency, and sustainability to transporta- tion systems. Several C-ITS applications are under development and will require thorough testing and evaluation before their deployment in the real-world. C- ITS depend on several sub-systems, which increase their complexity, and makes them difficult to evaluate.

Simulations are often used to evaluate many different automotive appli- cations, including C-ITS. Although they have been used extensively, simulation tools dedicated to determine all aspects of C-ITS are rare, especially human fac- tors aspects, which are often ignored. The majority of the simulation tools for C-ITS rely heavily on different combinations of network and traffic simulators. The human factors issues have been covered in only a few C-ITS simulation tools, that involve a driving simulator. Therefore, in this thesis, a C-ITS simu- lation framework that combines driving, network, and traffic simulators is pre- sented. The simulation framework is able to evaluate C-ITS applications from three perspectives; a) human driver; b) wireless communication; and c) traffic systems.

Cooperative Adaptive Cruise Control (CACC) and its applications are cho- sen as the first set of C-ITS functions to be evaluated. Example scenarios from CACC and platoon merging applications are presented, and used as test cases for the simulation framework, as well as to elaborate potential usages of it. Moreover, approaches, results, and challenges from composing the simulation framework are presented and discussed. The results shows the usefulness of the proposed simulation framework.

This paper is an experience report of team Halmstad from the participation in a competition organised by the i-GAME project, the Grand Cooperative Driving Challenge 2016. The competition was held in Helmond, The Netherlands, during the last weekend of May 2016. We give an overview of our car’s control and communication system that was developed for the competition following the requirements and specifications of the i-GAME project. In particular, we describe our implementation of cooperative adaptive cruise control, our solution to the communication and logging requirements, as well as the high level decision making support. For the actual competition we did not manage to completely reach all of the goals set out by the organizers as well as ourselves. However, this did not prevent us from outperforming the competition. Moreover, the competition allowed us to collect data for further evaluation of our solutions to cooperative driving. Thus, we discuss what we believe were the strong points of our system, and discuss post-competition evaluation of the developments that were not fully integrated into our system during competition time. © 2000-2011 IEEE.

Cooperative adaptive cruise control (CACC) is a cooperative intelligent transport systems (C-ITS) function, which especially when used in platooning applications, possess many expected benefits including efficient road space utilization and reduced fuel consumption. Cut-in manoeuvres in platoons can potentially reduce those benefits, and are not desired from a safety point of view. Unfortunately, in realistic traffic scenarios, cut-in manoeuvres can be expected, especially from non-connected vehicles. In this paper two different controllers for platooning are explored, aiming at maintaining the safety of the platoon while a vehicle is cutting in from the adjacent lane. A realistic scenario, where a human driver performs the cut-in manoeuvre is used to demonstrate the effectiveness of the controllers. Safety analysis of CACC controllers using time to collision (TTC) under such situation is presented. The analysis using TTC indicate that, although potential risks are always high in CACC applications such as platooning due to the small inter-vehicular distances, dangerous TTC (TTC < 6 seconds) is not frequent. Future research directions are also discussed along with the results.

Platooning refers to an application, where a group of connected and automated vehicles follow a lead vehicle autonomously, with short inter-vehicular distances. At merging points on highways such as on-ramp, platoons could encounter manually driven vehicles, which are merging on to the highways. In some situations, the manually driven vehicles could end up between the platooning vehicles. Such situations are expected and known as “cut-in” situations. This paper presents a simulation study of a cut-in situation, where a platoon of five vehicles encounter a manually driven vehicle at a merging point of a highway. The manually driven vehicle is driven by 37 test persons using a driving simulator. For the platooning vehicles, two longitudinal controllers with four gap settings between the platooning vehicles, i.e. 15 meters, 22.5 meters, 30 meters, and 42.5 meters, are evaluated. Results summarizing cut-in behaviours and how the participants perceived the situation are presented. Furthermore, the situation is assessed using safety indicators based on time-to-collision.

Cut-in situations occurs when a vehicle intention- ally changes lane and ends up in front of another vehicle or in-between two vehicles. In such situations, having a method to indicate the collision risk prior to making the cut-in maneuver could potentially reduce the number of sideswipe and rear end collisions caused by the cut-in maneuvers. This paper propose a new risk indicator, namely cut-in risk indicator (CRI), as a way to indicate and potentially foresee collision risks in cut-in situations. As an example use case, we applied CRI on data from a driving simulation experiment involving a manually driven vehicle and an automated platoon in a highway merging situation. We then compared the results with time-to-collision (TTC), and suggest that CRI could correctly indicate collision risks in a more effective way. CRI can be computed on all vehicles involved in the cut-in situations, not only for the vehicle that is cutting in. Making it possible for other vehicles to estimate the collision risk, for example if a cut-in from another vehicle occurs, the surrounding vehicles could be warned and have the possibility to react in order to potentially avoid or mitigate accidents. © 2020 IEEE.

In the near future, Cooperative Intelligent Transport System (C-ITS) applications are expected to be deployed. To support this, simulation is often used to design and evaluate the applications during the early development phases. Simulations of C-ITS scenarios often assume a fleet of homogeneous vehicles within the transportation system. In contrast, once C-ITS is deployed, the traffic scenarios will consist of a mixture of connected and non-connected vehicles, which, in addition, can be driven manually or automatically. Such mixed cases are rarely analysed, especially those where manually driven vehicles are involved. Therefore, this paper presents a C-ITS simulation framework, which incorporates a manually driven car through a driving simulator interacting with a traffic simulator, and a communication simulator, which together enable modelling and analysis of C-ITS applications and scenarios. Furthermore, example usages in the scenarios, where a manually driven vehicle cut-in to a platoon of Cooperative Adaptive Cruise Control (CACC) equipped vehicles are presented. © 2017 IEEE.

Wireless technology supporting vehicle-to-vehicle (V2V), and vehicle-to-infrastructure (V2I) communication, allow vehicles and infrastructures to exchange information, and cooperate. Cooperation among the actors in an intelligent transport system (ITS) can introduce several benefits, for instance, increase safety, comfort, efficiency. Automation has also evolved in vehicle control and active safety functions. Combining cooperation and automation would enable more advanced functions such as automated highway merge and negotiating right-of-way in a cooperative intersection. However, the combination have influences on the structure of the overall transport systems as well as on its behaviour. In order to provide a common understanding of such systems, this paper presents an analysis of cooperative ITS (C-ITS) with regard to dimensions of cooperation. It also presents possible influence on driving behaviour and challenges in deployment and automation of C-ITS.

Connected and automated driving in the context of cooperative intelligent transport systems (C-ITS) is an emerging area in transport systems research. Interaction and cooperation between actors in transport systems are now enabled by the connectivity by means of vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication. To ensure the goals of C-ITS, which are safer and more efficient transport systems, testing and evaluation are required before deployment of C-ITS applications. Therefore, this paper presents a simulation framework—consisting of driving-, traffic-, and network-simulators—for testing and evaluation of C-ITS applications. Examples of cooperative adaptive cruise control (CACC) applications are presented, and are used as test cases for the simulation framework as well as to elaborate on potential use cases of it. Challenges from combining the simulators into one framework, and limitations are reported and discussed. Finally, the paper concludes with future development directions, and applications of the simulation framework in testing and evaluation of C-ITS. © 2017 Elsevier Ltd. All rights reserved.

For a few decades, driving simulators have been supporting research and development of advanced driver assistance systems (ADAS). In the near future, connected vehicles are expected to be deployed. Driving simulators will need to support evaluation of cooperative driving applications within cooperative intelligent transportation systems (C-ITS) scenarios. C-ITS utilize vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication. Simulation of the inter vehicle communication is often not supported in driving simulators. On the other hand, previous efforts have been made to connect network simulators and traffic simulators, to perform C-ITS simulations. Nevertheless, interactions between actors in the system is an essential aspect of C-ITS. Driving simulators can provide the opportunity to study interactions and reactions of human drivers to the system. This paper present simulation of a C-ITS scenario using a combination of driving, network, and traffic simulators. The architecture of the solution and important challenges of the integration are presented. A scenario from Grand Cooperative Driving Challenge (GCDC) 2016 is implemented in the simulator as an example use case. Lastly, potential usages and future developments are discussed.

Vehicles in cooperative intelligent transport systems (C-ITS) often need to interact with each other in order to achieve their goals, safe and efficient transport services. Since human drivers are still expected to be involved in C-ITS, driving simulators are appropriate tools for evaluation of the C-ITS functions. However, driving simulators often simplify the interactions or influences from the ego vehicle on the traffic. Moreover, they normally do not support vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication, which is the main enabler for C-ITS. Therefore, to increase the C-ITS evaluation capability, a solution on how to extend a driving simulator with traffic and network simulators to handle cooperative systems is presented as a result of this paper. Evaluation of the result using two use cases is presented. And, the observed limitations and challenges of the solution are reported and discussed. © 2016 ACM, Inc.

At early market penetration, automated vehicles will share the road with legacy vehicles. For a safe transportation system, automated vehicle controllers therefore need to estimate the behavior of the legacy vehicles. However, mismatches between the estimated and real human behaviors can lead to inefficient control inputs, and even collisions in the worst case. In this paper, we propose a framework for evaluating the impact of model mismatch by interfacing a controller under test with a driving simulator. As a proof- of-concept, an algorithm based on Model Predictive Control (MPC) is evaluated in a braking scenario. We show how model mismatch between estimated and real human behavior can lead to a decrease in avoided collisions by almost 46%, and an increase in discomfort by almost 91%. Model mismatch is therefore non-negligible and the proposed framework is a unique method to evaluate them. © 2018 IEEE.

Conformance testing is a formal and structured approach to verifying system correctness. We propose a conformance testing algorithm for cyber-physical systems, based on the notion of hybrid conformance by Abbas and Fainekos. We show how the dynamics of system specification and the sampling rate play an essential role in making sound verdicts. We specify and prove error bounds that lead to sound test-suites for a given specification and a given sampling rate. We use reachability analysis to find such bounds and implement the proposed approach using the CORA toolbox in Matlab. We apply the implemented approach on a case study from the automotive domain. © 2017 The Author(s).

We present a process for sound conformance testing of cyber-physical systems, which involves functional but also non-functional aspects. The process starts with a hybrid model of cyber-physical systems in which the correct behavior of the system (at its interface level) is specified. Such a model captures both discrete behavior and evolution of continuous dynamics of the system in time. Since conformance testing inherently involves comparing continuous dynamics, the key parameters of the process are (1) the conformance bounds defining when two signals are sufficiently close to each other, and (2) the permitted error margin in the conformance analysis introduced by sampling of continuous signals. The final parameter of this process is (3) finding (and adjusting) the sampling rate of the dynamic behavior. In the specified process, we provide different alternatives for fixing the error margin of the conformance testing if the sampling rate is fixed, establishing the sampling rate if the error margin is fixed and finding conformance bounds once the sampling rate and the error margin are fixed. © 2017 IEEE.

Cooperative awareness basic services are key components of several Connected Autonomous Vehicles (CAV) functions. We present a rigorous approach to the analysis of cooperative awareness basic services in a CAV setup. Our approach addresses a major challenge in the traditional analysis techniques of such services, namely, coming up with effective scenarios that can meaningfully cover their various behaviours, exercise the limits of these services and come up with a quantitative means for design-space exploration.Our approach integrates model-based testing and search-based testing to automatically generate scenarios and steer the scenario generation process towards generating inputs that can lead to the most severe hazards. Additionally we define other objectives that maximise the coverage of the model and the diversity of the generated test inputs. The result of applying our technique to the analysis of cooperative awareness services leads to automatically generated hazardous scenarios for parameters that abide by the ETSI ITS-G5 vehicular communications standard. We show that our technique can be used as an effective design-space exploration method and can be used to design adaptive protocols that can mitigate the hazards detected through our initial analysis. © 2020 by IEEE

This paper provides some background and the roadmap of the AUTO-CAAS project, which is a 3-year project financed by the Swedish Knowledge Foundation and is ongoing as a joint project among three academic and industrial partners. The aim of the project is to exploit the formal models of the AUTOSAR standard, developed by the industrial partner of the project Quviq AB, in order to predict possible future failures in concrete implementations of components. To this end, the deviations from the formal specification will be exploited to generate test-cases that can push concrete components to the corners where such deviation will result in observable failures. The same information will also be used in the diagnosis of otherwise detected failures in order to pinpoint their root causes.

Data offloading using vehicles is one of the most challenging tasks to perform due to the high mobility of vehicles. There are many solutions available for this purpose, but due to the inefficient management of data along with the control decisions, these solutions are not adequate to provide data offloading by making use of the available networks. Moreover, with the advent of 5G and related technologies, there is a need to cope with high speed and traffic congestion in the existing infrastructure used for data offloading. Hence, to make intelligent decisions for data offloading, an SDN-based scheme is presented in this article. In the proposed scheme, an SDNbased controller is designed that makes decisions for data offloading by using the priority manager and load balancer. Using these two managers in SDN-based controllers, traffic routing is managed efficiently even with an increase in the size of the network. Moreover, a single-leader multi-follower Stackelberg game for network selection is also used for data offloading. The proposed scheme is evaluated with respect to several parameters where its performance was found to be superior in comparison to the existing schemes. © Copyright 2017 IEEE

Vehicle-to-Everything (V2X) communication is essential for facilitating connected and automated driving, where vehicles and other road traffic participants share data instantaneously and cooperate to solve tricky traffic situations in milliseconds. This paper proposes two stochastic models for the V2X standard IEEE 802.11p to characterize amongst other things the Age of Information (AoI), a recently-proposed metric that measures the freshness of information. The first model is based on renewal process analysis of a tagged station with mean field approximation, while the second one adopts Markov chain approach with network level view. Analytical results show that IEEE 802.11p, given its adaptability to event-triggered and aperiodic messaging, supports advanced cooperative driving scenarios.

Platooning is both a challenging and rewarding application. Challenging since strict timing and reliability requirements are imposed by the distributed control system required to operate the platoon. Rewarding since considerable fuel reductions are possible. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if retransmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability compared to pure 802.11p. © 2015 IEEE.

Lately, all the top truck manufacturers are investing considerable resources in the research and development of platooning systems which would allow vehicles to save fuel and improve safety by travelling in a close-following manner. The platooning system requires frequent and reliable vehicle-to-vehicle communications. As platooning takes place in a vehicular ad hoc network, the use of IEEE 802.11p is close to mandatory. However, the 802.11p medium access method suffers from packet collisions and random delays. Most ongoing research suggests using TDMA on top of 802.11p as a potential remedy. However, TDMA requires synchronization and is not very flexible if the beacon frequency needs to be updated, the number of platoon members changes, or if re-transmissions for increased reliability are required. We therefore suggest a token-passing medium access method where the next token holder is selected based on beacon data age. This has the advantage of allowing beacons to be re-broadcasted in each beacon interval whenever time and bandwidth are available. We show that our token-based method is able to reduce the data age and considerably increase reliability considerably compared to pure 802.11p.

Molecular communication is a relatively new communication paradigm for nanomachines where the communication is realized by utilizing existing biological components found in nature. In recent years researchers have proposed using bacteria to realize molecular communication because the bacteria have the ability to swim and migrate between locations, carry DNA contents (i.e. plasmids) that could be utilized for information storage, and interact and transfer plasmids to other bacteria (one of these processes is known as bacterial conjugation). However, current proposals for bacterial nanonetworks have not considered the internal structures of the nanomachines that can facilitate the use of bacteria as an information carrier. This article presents the types and functionalities of nanomachines that can be utilized in bacterial nanonetworks. A particular focus is placed on the bacterial conjugation and its support for multihop communication between nanomachines. Simulations of the communication process have also been evaluated, to analyze the quantity of bits received as well as the delay performances. Wet lab experiments have also been conducted to validate the bacterial conjugation process. The article also discusses potential applications of bacterial nanonetworks for cancer monitoring and therapy. © 2014 IEEE.

Domain-Specific Languages (DSLs) play an important role in both practice and education. But developing them is challenging, because a DSL must ultimately satisfy a large and complex set of user/customer requirements to fulfil its intended role, and neither requirements nor users are fully available at all times during the development process. Requirements can be elicited using agile methods but such methods assume the availability of the users. The situation is further complicated when the user base is primarily students and when enhanced learning is a key requirement. In this paper we propose developing DSLs, especially educational ones, as online applications. We analyze how this can help requirement elicitation and learning. Being online brings language development closer to the user, yielding new opportunities to improve and accelerate the language design process. It is also well-matched to agile methods, since web- based analytics provide an abundant source of data that integrates naturally into the development process. As an example, we consider applying the method to Acumen, a DSL designed to support teaching Cyber-Physical Systems.

Prospective IEEE 802.11p-based vehicular surveillance system, where video from the vehicle on-board camera is transmitted to the management center, is considered. Multi-hop transmission from the vehicle to the nearest roadside unit and then-via other roadside units-to the gateway is addressed. In this letter we assess the feasibility of such system by analyzing the video end-to-end distortion for a target vehicle, located several hops away from the gateway, when it is alone or there are also other vehicles transmitting video. We demonstrate the importance of dynamic adaptation of the video bit rate of each vehicle depending on the number and positions of the participating vehicles. © 2014 IEEE.

The proceedings contain 18 papers. The topics discussed include: network coding as a WiMAX link reliability mechanism; initialization procedure of wireless network coding with hierarchical decode and forward strategy in random connectivity networks; a coded DHA FH OFDMA system with a noncoherent ML detector under multitone jamming; analysis of inter-RSU beaconing interference in VANETs; survey of energy efficient tracking and localization techniques in buildings using optical and wireless communication media; network coding as a WiMAX link reliability mechanism: an experimental demonstration; spectrum sensing with USRP-E110; power control for wireless networks with a limited number of channels; a measurement study for predicting throughput from LQI and RSSI; reality considerations when designing a TDMA-FDMA based link-layer for real-time WSN; and wireless groupcast routing with palette of transmission methods.

This book chapter introduces the use of Continuous Time Markov Networks (CTMN) to analytically capture the operation of Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) networks. It is of tutorial nature, and it aims to be an introduction on this topic, providing a clear and easy-to-follow description. To illustrate how CTMN can be used, we introduce a set of representative and cutting-edge scenarios, such as Vehicular Ad-hoc Networks (VANETs), Power Line Communication networks and multiple overlapping Wireless Local Area Networks (WLANs). For each scenario, we describe the specific CTMN, obtain its stationary distribution and compute the throughput achieved by each node in the network. Taking the per-node throughput as reference, we discuss how the complex interactions between nodes using CSMA/CA have an impact on system performance.

Functional*Reactive Programming (FRP) is a declarative approach to modeling and building reactive systems. Priority-based FRP (P-FRP) is a formalism of FRP that guarantees real-time response. Unlike the classical preemptive model1 of real-time systems, preempted tasks in PFRP are aborted and have to restart when higher priority tasks have completed. Due to this abort-restart of nature of preemption, there is no single critical instant of release that leads to Worst-Case Response Time (WCRT) of lower priority P-FRP tasks. At this time, the only method for determining the WCRT is through an exhaustive enumeration of all release offsets of higher priority tasks between the release and deadline of the lower priority task. This makes the computational cost of WCRT dependent on the deadline of a task, and when such deadlines are large the computational costs of this technique make it infeasible even for small task sets. In this paper, we show that the release offsets of higher priority tasks have a lower and upper bound and present techniques to derive these bounds. By enumerating only those release offsets while lie within our derived bounds the number of release scenarios that have to be enumerated is significantly reduced. This leads to lower computational costs and makes determination of the WCRT in P-FRP a practically feasible proposition. © 2011 IEEE.

Overtaking on rural roads may cause severe accidents when oncoming traffic is detected by a driver too late, or its speed is underestimated. Recently proposed cooperative overtaking assistance systems are based on real-time video transmission, where a video stream captured with a camera installed at the windshield of a vehicle is compressed, broadcast through the wireless channel, and displayed to the drivers of vehicles driving behind. In such a system, it is of ultimate importance to deliver video information about the opposite lane with low end-to-end latency and good visual quality. In this paper, we propose reallocating the wireless channel resources in favor of the part of the captured video frame containing the image of the oncoming vehicle. To achieve this goal, we apply automotive radar for oncoming vehicle detection, and we use the image of this vehicle as a region-of-interest (ROI) for the video rate control. We present the theoretical framework, which describes the basics of such an approach and can serve as a useful guideline for the future practical implementation of the overtaking assistance systems. The benefits of our proposal are demonstrated in relation to the practical scenario of H.264/Advance Video Coding (AVC), IEEE 802.11p/Wireless Access for Vehicular Environments (WAVE) intervehicle communication standards, and currently used automotive radars.

Real-time video delivery in Vehicle-to-Infrastructure (V2I) scenario enables a variety of multimedia vehicular services. We conduct experiments with Dedicated Short Range Communications (DSRC) transceivers located in the mutual proximity and exchanging Skype video calls traffic. We demonstrate that the lack of coordination between the users both at the application as well as Medium Access Control (MAC) layers results in problems with quality of service provisioning even for the setup without vehicular mobility. © Copyright 2017 IEEE

This work is dedicated to a live video streaming in vehicular networks where the application-based inter-packet forward error correction is used for the packet loss protection. A practical way to apply such a protection at the video encoder side for the unknown channel loss rate is proposed. Experimental results which demonstrate the performance for the proposed approach for a scalable extension of the H.264/AVC standard (H.264/SVC) and for the non-standardized video codec based on three-dimensional discrete wavelet transform (3-D DWT) are provided.

In recently proposed cooperative overtaking assistance systems a video stream captured by a windshield-mounted camera in a vehicle is compressed and broadcast to the vehicle driving behind it, where it is displayed to the driver. It has been shown that this system can provide robust operation if video codec channel adaptation is undertaken by exploiting information from the cooperative awareness messages about any forthcoming increases in the multiple access channel load. In this letter we demonstrate the gains achievable in system performance when the video transmitter power control is also used. © 1997-2012 IEEE.

Prospective IEEE 802.11p-enabled automotive video applications are identified. Preliminary experimental results of inter-vehicular live video streaming for surveillance applications are presented. A test-bed for the demonstration of the achievable visual quality under different channel conditions is described.

IEEE 802.11p vehicle-to-vehicle and vehicle-to-infrastructure communication technology is currently an emerging research topic in both industry and academia. Respective spectrum allocation of 10 MHz channels in the 5.9 GHz band for USA and Europe allows considering inter-vehicle transmission of a live video information as a basis, which enables a new class of safety and infotainment automotive applications such as road video surveillance. This paper is first of its kind where such a video transmission system is developed and experimentally validated. We propose a low-complexity unequal packet loss protection and rate control algorithms for a scalable video coding based on the three-dimensional discrete wavelet transform. We show that in comparison with a scalable extension of the H.264/AVC standard the new codec is less sensitive to packet losses, has less computational complexity and provides comparable performance in case of unequal packet loss protection. It is specially designed to cope with severe channel fading typical for dynamic vehicular environments and has a low complexity, making it a feasible solution for real-time automotive surveillance applications. Extensive measurements obtained in realistic city traffic scenarios demonstrate that good visual quality and continuous playback is possible when the moving vehicle is in the radius of 600 meters from the roadside unit. ©2014 IEEE

Advanced digital signal processing systems require specialized high-performance embedded computer architectures. The term high-performance translates to large amounts of data and computations per time unit. The term embedded further implies requirements on physical size and power efficiency. Thus the requirements are of both functional and non-functional nature. This thesis addresses the development of high-performance digital signal processing systems relying on manycore technology. We propose building two-level hierarchical computer architectures for this domain of applications. Further, we outline a tool flow based on methods and analysis techniques for automated, multi-objective mapping of such applications on distributed memory manycore processors. In particular, the focus is put on how to provide a means for tunable strategies for mapping of task graphs on array structured distributed memory manycores, with respect to given application constraints. We argue for code mapping strategies based on predicted execution performance, which can be used in an auto-tuning feedback loop or to guide manual tuning directed by the programmer. Automated parallelization, optimisation and mapping to a manycore processor benefits from the use of a concurrent programming model as the starting point. Such a model allows the programmer to express different types and granularities of parallelism as well as computation characteristics of importance in the addressed class of applications. The programming model should also abstract away machine dependent hardware details. The analytical study of WCDMA baseband processing in radio base stations, presented in this thesis, suggests dataflow models as a good match to the characteristics of the application and as execution model abstracting computations on a manycore. Construction of portable tools further requires a manycore machine model and an intermediate representation. The models are needed in order to decouple algorithms, used to transform and map application software, from hardware. We propose a manycore machine model that captures common hardware resources, as well as resource dependent performance metrics for parallel computation and communication. Further, we have developed a multifunctional intermediate representation, which can be used as source for code generation and for dynamic execution analysis. Finally, we demonstrate how we can dynamically analyse execution using abstract interpretation on the intermediate representation. It is shown that the performance predictions can be used to accurately rank different mappings by best throughput or shortest end-to-end computation latency.