In-vehicle Communication Research Articles

Generalized Asynchronous Time-Triggered Scheduling for FlexRay

FlexRay is a hybrid communication protocol tailored to the requirements in the automotive domain, supporting both time-triggered and event-triggered communication with high data-rates. The time-triggered static segment is commonly used for in-vehicle communication while the event-triggered dynamic segment is used for diagnostics and configuration. This paper addresses the problem of synthesizing schedules for the static FlexRay segment for asynchronous scheduling, following the design approach of current automotive architectures. Previous approaches largely focused on FlexRay 2.1 while the few existing approaches for FlexRay 3.0 are nonoptimal in several aspects. As a remedy, our framework makes use of all new features of version 3.0 while supporting the still predominantly used FlexRay 2.1, making it backward compatible. The following approaches are proposed: 1) a single-stage integer linear programming (ILP) approach that determines an optimal solution but does not scale; 2) a multistage ILP for combining previously generated subsystem schedules to a global schedule. It clearly improves the scalability but is not optimal. The multistage approach allows to integrate and convert existing FlexRay 2.1 schedules into a FlexRay 3.0 schedule which is important for legacy reasons, i.e., to reduce testing and certification efforts; 3) a greedy heuristic which scales well and obtains high quality solutions in comparison with the optimal solution, but is unsuitable to integrate existing schedules; and 4) metaheuristic approaches based on genetic algorithms or simulated annealing to evaluate the benefits of the proposed approaches.

New ECU Attestation and Encryption Mechanism for In-Vehicle Communication

Aiming at the secure problem of which vehicle ECU’s firmware can be easily tampered with and in-vehicle communication isn’t encrypted, a key pre-distribution system is introduced to propose an ECU attestation and in-Vehicle communication encryption mechanism. It adopts hash algorithm to attestation ECU’s integrity. And it utilizes symmetry encryption algorithm to encrypt the communication. The session keys are produced and distributed by key pre-distribution system which assure each ECU’s session key is unique. Simulation experimental results show this mechanism is low cost and has high calculating speed and high safety. And it can solve the problem of ECU’s firmware tampering, ECU forgery, replay attacks and data betray.

Optimal scheduling of the flexray static segment based on two-dimensional bin-packing algorithm

FlexRay is a reliable and hard real-time in-vehicle communication protocol that is strongly promoted by car manufacturers as the de facto standard in the automotive domain. The protocol offers both a time-triggered and an eventtriggered architecture. This paper focuses on the optimal scheduling of the time-triggered component of FlexRay known as the static (ST) segment using a two-dimensional bin-packing technique. To maximize the bandwidth utilization in the ST segment, a fast heuristic as well as an efficient integer linear programming approach are proposed. Our methods directly schedule signals into slots including frame packing, according to signal-based data scheduling and the slot/ cycle multiplexing mechanisms presented by the latest version of the FlexRay protocol. The benefits of our proposed methods are demonstrated by extensive experiments on synthetic and an automotive X-by-wire system case study. An additional test case is examined to emphasize the superior performance of the proposed approach relative to that of existing optimal scheduling approaches.

A Multichannel Medium Access Control Protocol for Vehicular Power Line Communication Systems

In-vehicle communications are emerging to play an important role in the continued development of reliable and efficient X-by-Wire applications in new vehicles. Since vehicle devices, sensors, and the electronic control unit (ECU) are already connected to power wires, the advancement of power line communications (PLCs) can provide a very low cost and virtually free platform for in-vehicle communications. In this paper, we propose a medium access control (MAC) protocol for vehicular PLC systems, where multiple nodes are competing for transmission over the direct current (dc) power line. The proposed protocol uses a combination of time and frequency multiplexing and consists of two key features: 1) a distributed channel selection policy to arbitrate packet transmission across different channels and provide robustness against interference and noise and 2) a distributed collision resolution algorithm to allow efficient nodes completion over selected channels. Specifically, the collision resolution algorithm is optimized with respect to the channel policy such that the success probability of transmission in each channel is maximized. Numerical results are also supplemented to validate the performance of the proposed protocol and provide useful guidelines for developing a robust contention-based MAC protocol for vehicular PLC systems.

Security-Aware Obfuscated Priority Assignment for Automotive CAN Platforms

Security in automotive in-vehicle networks is an increasing problem with the growing connectedness of road vehicles. This article proposes a security-aware priority assignment for automotive controller area network (CAN) platforms with the aim of mitigating scaling effects of attacks on vehicle fleets. CAN is the dominating field bus in the automotive domain due to its simplicity, low cost, and robustness. While messages might be encrypted to enhance the security of CAN systems, their priorities are usually identical for automotive platforms, comprising generally a large number of vehicle models. As a result, the identifier uniquely defines which message is sent, allowing attacks to scale across a fleet of vehicles with the same platform. As a remedy, we propose a methodology that is capable of determining obfuscated message identifiers for each individual vehicle. Since identifiers directly represent message priorities, the approach has to take the resulting response time variations into account while satisfying application deadlines for each vehicle schedule separately. Our approach relies on Quadratically Constrained Quadratic Program (QCQP) solving in two stages, specifying first a set of feasible fixed priorities and subsequently bounded priorities for each message. With the obtained bounds, obfuscated identifiers are determined, using a very fast randomized sampling. The experimental results, consisting of a large set of synthetic test cases and a realistic case study, give evidence of the efficiency of the proposed approach in terms of scalability. The results also show that the diversity of obtained identifiers is effectively optimized with our approach, resulting in a very good obfuscation of CAN messages in in-vehicle communication.

In-Vehicle Networks Outlook: Achievements and Challenges

This paper presents a comprehensive survey of five most widely used in-vehicle networks from three perspectives: system cost, data transmission capacity, and fault-tolerance capability. The paper reviews the pros and cons of each network, and identifies possible approaches to improve the quality of service (QoS). In addition, two classifications of automotive gateways have been presented along with a brief discussion about constructing a comprehensive in-vehicle communication system with different networks and automotive gateways. Furthermore, security threats to in-vehicle networks are briefly discussed, along with the corresponding protective methods. The survey concludes with highlighting the trends in future development of in-vehicle network technology and a proposal of a topology of the next generation in-vehicle network.

The Research of CIR Based on Communication Technology of GSM-R

In order to realize the wireless communication function of railway locomotives, Cab Integrated Wireless communication equipment (referred to as CIR) as the railway wireless communication system in China's railway locomotives equipment, because has powerful functions, high degree of standardization, and flexible operating characteristics emerged. CRI is based on the GSM-R digital mobile communication technology, GPS global positioning technology, 450MHz and 800MHz analog wireless communications technology such as the development of comprehensive in-vehicle communications equipment. It is the ground of GSM-R equipment and 450MHz, 800MHz and other ground equipment, together form a complete rail integrated wireless communications network.

Use of Controller Area Network (CAN) Data To Determine Field Efficiencies of Agricultural Machinery

Abstract. Controller Area Network (CAN) bus is used on current agricultural equipment for in-vehicle communication among multiple microcontrollers. In this study, CAN data was collected from the tractor diagnostic port during three field operations: anhydrous ammonia (NH3) application, field cultivation, and planting. Specifically, CAN messages corresponding to engine fuel use rate were filtered, decoded, and analyzed. High fuel use rates were recorded from the tractor when implements were engaged in the soil compared to when the implements were lifted out of the ground at the end of the passes or, when the tractor was turning and idling. Threshold fuel rates (TFR) in liter per hour per tool for each operation were established based on the draft force requirements of the implements to distinguish between working and dwell periods. Using the calculated TFRs of 2.58 to 2.64 Lh-1tool-1, 0.41 to 0.50 Lh-1tool-1 and 1.46 to 1.65 Lh-1row-1, average field efficiencies (FE) of anhydrous NH3 application, field cultivation and planting were determined to be 71%, 71% and 68%, respectively. It was found that FE values for the planting operation were highly sensitive to variation in TFR when contrasted with anhydrous NH3 application and field cultivation operations.

Implementation of an Integrated Controller for a Robot Hand Base on a Vehicle Communication System

Intelligent robots commonly adopt Network-Based Control Systems (NBCS). For control of a robot hand or a robot head, many sensor data and control commands need to be transmitted in real time, so they have necessitated communication systems with high transmission capability. Traditionally, CAN is widely used for intelligent robots, but it presents bandwidths that are too low for the control of a high performance system. In this paper, the relation between the transmission period and the performance of a multi-motor control system is analyzed, and a multi-motor control system for a human robot hand is implemented based on the FlexRay communication system, which is an emerging in-vehicle communication network system. FlexRay parameter optimization for a robot system is studied, and a real position control test is conducted, to validate the implemented system.

The answer is rolling on wheels: Modeling and performance evaluation of in-cabin Wi-Fi communications

Automobile manufacturers are delivering a new generation of connected vehicles with in-cabin Wi-Fi devices, enabling advances in a wide range of in-vehicle communications and infotainment capabilities. The communication performance is a key factor enabling the instant multimedia streaming. A fundamental question remains to be explored: as every running vehicle is equipped with an in-cabin Wi-Fi, how will be the communication performance affected by the varied number of surrounding vehicles, the transmission power and the data rate? In order to answer this question, we establish analytical models that embody the novel in-cabin Wi-Fi features. We set up a new evaluation platform for in-cabin Wi-Fi communications based on extensive simulations. We report how the performance of in-cabin Wi-Fi communications is affected by traffic conditions and Wi-Fi hotspot settings. Through extensive analysis and evaluations, we show how to configure the in-cabin Wi-Fi to guarantee the quality of service.

Multi-System Integration Scheme for Intelligence Transportation System Applications

With more and more devices being introduced into vehicles to provide additional driving functionality, driving experience is seemingly getting more complex and frustrated due to an influx of individual messages. To help manage the information, individuals need a mechanism to orchestrate the operations of the in-vehicle devices so that such frustration can be eased. In this study, the authors propose an in-vehicle communication scheme for multi-system integration, where an effective system service discovery protocol is used. This proposed design also contains mutual communication methods and the data exchange methodologies for system integration. Experimental results with performance evaluation demonstrate the success of the proposed design.

Quantifying Notions of Extensibility in FlexRay Schedule Synthesis

FlexRay has now become a well-established in-vehicle communication bus at most original equipment manufacturers (OEMs) such as BMW, Audi, and GM. Given the increasing cost of verification and the high degree of crosslinking between components in automotive architectures, an incremental design process is commonly followed. In order to incorporate FlexRay-based designs in such a process, the resulting schedules must be extensible , that is: (i) when messages are added in later iterations, they must preserve deadline guarantees of already scheduled messages, and (ii) they must accommodate as many new messages as possible without changes to existing schedules. Apart from extensible scheduling having not received much attention so far, traditional metrics used for quantifying them cannot be trivially adapted to FlexRay schedules. This is because they do not exploit specific properties of the FlexRay protocol. In this article we, for the first time, introduce new notions of extensibility for FlexRay that capture all the protocol-specific properties. In particular, we focus on the dynamic segment of FlexRay and we present a number of metrics to quantify extensible schedules. Based on the introduced metrics, we propose strategies to synthesize extensible schedules and compare the results of different scheduling algorithms. We demonstrate the applicability of the results with industrial-size case studies and also show that the proposed metrics may also be visually represented, thereby allowing for easy interpretation.

Design and Evaluation of Telematics User Interface for Ubiquitous Vehicle

In the ubiquitous computing environment, a ubiquitous vehicle will be a communication node in the vehicular network as well as the means of ground transportation. It will make humans and vehicles seamlessly and remotely connected. Especially, one of the prominent services in the ubiquitous vehicle is the vehicle remote operation. However, mutual-collaboration with the in-vehicle communication network, the vehicle-to-vehicle communication network and the vehicle-to-roadside communication network is required to provide vehicle remote operation services. In this paper, an Internet-based human-vehicle interfaces and a network architecture is presented to provide remote vehicle control and diagnosis services. The performance of the proposed system is evaluated through a design and implementation in terms of the round trip time taken to get a vehicle remote operation service.

Robust Priority Assignments for Extending Existing Controller Area Network Applications

The usage of the controller area network (CAN) as an in-vehicle communication bus requires finding feasible and robust priority orders such that each message transmitted on the bus meets its specified deadline and tolerates potential transmission errors. Although such priority orders can be determined by available algorithms whenever they exist, it is always assumed that a CAN priority order is computed from scratch. In practical applications, it is frequently necessary to extend an existing message set by new messages. In this case, a feasible priority order that retains the standardized IDs of the existing messages and assigns suitable priorities to the new messages needs to be found. This paper proposes an algorithm for the computation of robust priority orders that solves the stated problem of extending existing message sets. First, bounds for the priorities of new messages are determined and then the most robust priority order that keeps the IDs of the existing messages is computed. The obtained algorithms are proved to yield correct results and are illustrated by detailed scheduling examples.

Modeling of OFDM Based Transceiver for Broadband Powerline Communication

In the recent past power line communication has emerged as an attractive choice for high speed data transfer and is looked upon as inexpensive and reliable media suitable for broadband internet access, home and office automation, in-vehicle data communication etc. In this paper we present an architecture for the physical layer of a PLC transceiver based on Orthogonal Frequency Division Multiplexing (OFDM) and the impact on multipath distortion for PLC transmission in terms of bit error rate. Since there is no standard PLC channel model available, a widely accepted multipath channel model is used for simulation purpose. Simulation results as well as FPGA synthesis verify the effectiveness of the proposed architecture for PLC modem design at 110 Mbps data rate.

Cars as a Diffuse Network of Road-Environment Monitoring Nodes

The present paper aims to describe the conceptual idea to use cars as sensors to measure and acquire data related road environment. The parameters are collected using only standard equipment commonly installed and operative on commercial cars. Real sensors and car sub-systems (e.g. thermometers, accelerometers, ABS, ESP, and GPS) together with other “implicit” sensors (e.g. fog lights, windscreen wipers) acquire and contain information. They are shared inside an in-vehicle communication network using mainly the standard CAN bus and can be collected by a simple central node. This node can also be available on the market without too expensive costs thanks to some companies which business is devoted to car fleet monitoring. All the collected data are then geolocalized using a standard GPS receiver and sent to a remote elaboration unit, exploiting mobile network technologies such as GPRS or UMTS. A large number of cars, connected together in a diffuse Wireless Sensor Network, allow the elaboration unit to realize some info-layers put at the disposal of a car driver. Traffic, state of the road and other information about the weather can be received by car drivers using an ad hoc developed mobile application for smartphone which can give punctual information related to a specific route, previously set on the mobile phone navigator. The description of some experimental activities is presented, some technical points will be addressed and some examples of applications of the network of cars “as sensors” will be given.

Towards a distributed secure in-vehicle communication architecture for modern vehicles

Modern automotive vehicles are becoming a collection of interconnected embedded subsystems, where the mechanical parts are controlled by electronic ones and the vehicle is transformed into a mobile information system. However, the industry standards for in-vehicle communication are not following long-established computer security policies. This trend not only makes vehicles prone to thefts and automated attacks, but also endangers passengers safety.This paper analyzes current practices and standards of the automotive industry, highlighting several vulnerabilities that stress the need to change the way that in-vehicle communication is handled. To this end, we present a novel vehicle security architecture that supports two new features; users with different access rights and roles, and mutual authentication of ECUs. These features can enable a more distributed security architecture and prevent many attacks, or at least trigger adequate alarms to detect and mitigate them, or allow backtracking.

Modeling the interference generated from car base stations towards indoor femto-cells

In future wireless networks, a significant number of users will be vehicular. One promising solution to improve the capacity for these vehicular users is to employ moving relays or car base stations. The system forms cell inside the vehicle and then uses rooftop antenna for backhauling to overcome the vehicular penetration loss. In this paper, we develop a model for aggregate interference distribution generated from moving/parked cars to indoor users in order to study whether indoor femto-cells can coexist on the same spectrum with vehicular communications. Since spectrum authorization for vehicular communications is open at moment, we consider two spectrum sharing scenarios (i) communication from mounted antennas on the roof of the vehicles to the infrastructure network utilizes same spectrum with indoor femto-cells (ii) in-vehicle communication utilizes same spectrum with indoor femto-cells while vehicular to infrastructure (V2I) communication is allocated at different spectrum. Based on our findings we suggest that V2I and indoor femto-cells should be allocated at different spectrum. The reason being that mounted roof-top antennas facing the indoor cells generate unacceptable interference levels. On the other hand, in-vehicle communication and indoor cells can share the spectrum thanks to the vehicle body isolation and the lower transmit power levels that can be used inside the vehicle.

The Impact of Network Topologies on the Performance of the In-Vehicle Network

Today's vehicles contain hundreds of circuits, sensors and around 80-120 Electronic Control Units(ECUs). The communication is needed among many circuits and functions of a vehicle. In earlier vehicle systems, this type of communication was handled via a dedicated wire through point-to-point connections. If all possible combinations of switches, sensors, ECUs and other electronic devices in fully featured vehicles are accumulated, the resulting number of connections and dedicated wiring is enormous. Hence networking of these components is necessary to reduce the complexity of electronics inside a vehicle. In-vehicle networking provides a more efficient method for today's complex in-vehicle communications. This paper focuses on the comparison of the performance of ring and star network topologies on the basis of bus load.

Fault Diagnostics Using Network Motif Signature


 
 
 In modern vehicles, controls are distributed over multiple Electronic Control Units (ECUs) that are connected through in-vehicle communication networks. Fault diagnostics for such a distributed control system is very challenging, which has resulted in many no-trouble-found (NTF) cases during warranty repairs. To address this problem, we propose a novel network-theoretic approach that detects, identifies, and localizes faults using both the structure of the communication network (topological information) and message flow information. The proposed method not only enables the characterization of normal operation and a-priori known faults across communication networks, which is already beyond the current practice of individual ECU centric diagnostics, but also the diagnostics of unknown or cascading failures emerging from unexpected operational environments.