Mehrnoush Rahmani

Traffic Shaping for Resource-Efficient In-Vehicle Communication

In-vehicle communication has become complex and costly due to the growing number of automotive network systems applied for different data types. In this work, our previously proposed in-vehicle network architecture that is based on Internet protocol (IP) and full-duplex switched Ethernet (IP/Ethernet) is further investigated for real-time audio and video streaming. Quality-of-service (QoS) and resource usage are analyzed for selected IP/Ethernet-based network topologies. Traffic shaping is used to reduce the required network resources and consequently the cost. A novel traffic shaping algorithm is presented that outperforms other traffic shapers in terms of resource usage when applied to variable bit rate video sources in the proposed double star topology. In addition, a new architecture design is introduced for traffic shaper implementation in switches which operates on a per stream basis. Analytical and simulation results confirm that the proposed network architecture with traffic shaping is well-adapted for in-vehicle communication.

Performance analysis of different network topologies for in-vehicle audio and video communication

In-vehicle audio and video communication has recently received considerable attention in the automotive industry. First, because of the increasing number of audio and video consumer electronic devices and the requirement to integrate them in the car. Second, because of the rapid growing of realtime audio and video based driver assistance systems. So far, the interconnection of in-vehicle stream oriented devices has been performed by different and automotive specific network systems with limited transmission capacities. IP over Ethernet provides good conditions for audio and video streaming by offering high transmission capacities. In order to design an appropriate IP/Ethernet network for audio and video communication in the car, the selection of the right network topology is essential. In this work, several network topologies are compared by their Quality of Service (QoS) performance and production cost. Appropriate topologies are proposed.

A Novel Network Architecture for In-Vehicle Audio and Video Communication

In-vehicle audio/video communication has recently received considerable attention in the automotive industry. First, because of the increasing number of audio/video oriented nomadic devices in the consumer electronic market and the requirement to integrate them in the car. Second, because the number of real-time audio/video based driver assistance systems is growing fast. So far, the interconnection of in-vehicle stream oriented devices has been performed by different and proprietary, automotive oriented network systems with limited transmission capacities. Ethernet provides good conditions for audio/video streaming, due to its high transmission capacity. But it unfortunately fails in providing adequate QoS. In this work, a new network architecture for in-car audio/video communication based on the Ethernet technology is introduced and solutions are proposed to extend Ethernet with QoS guarantees while keeping its cost low.

Coexistence of Time-Triggered and Event-Triggered Traffic in Switched Full-Duplex Ethernet Networks

In the recent years, the Ethernet technology has grown rapidly, mainly due to its applicability in local area networks. High data rates, low cost, collision reduction with the full-duplex approach and the elimination of chaining limits inherent in hubbed Ethernet networks have made the switched Ethernet a dominant network technology. Although the switch technology has improved significantly, the delays appearing in the switches are still not acceptable for time critical applications. This is specially the case when several cascaded switches are applied. Within the scope of developing a new network architecture for the in-vehicle communication, the time constraints of a switched Ethernet network are addressed in this paper. In order to comply with the delay bounds of time critical applications in the automotive field, a cost-effective approach is proposed and analyzed for several cascaded switches.

A novel network design for future IP-based driver assistance camera systems

The current in-vehicle driver assistance network system is realized via point-to-point connections. Due to the growing number of cameras, the in-vehicle network systems are becoming increasingly complex, inflexible and costly. In our previous work, we have proposed an IP over Ethernet (IP/Ethernet) in-vehicle network system and have shown the necessity of video compression for driver assistance cameras. In this paper, all existing camera systems in the car are presented and classified. Their current connections are introduced and a new network topology based on IP/Ethernet is proposed to interconnect the cameras. We also investigate how video codecs in the car should be parametrized in order to avoid negative effects for driver assistance image processing algorithms while reducing the overall cost. The results show compression ratio regions that do not negatively affect the image processing tasks but instead improve their performance.

A comparative study of network transport protocols for in-vehicle media streaming

We analyze and compare various transport protocols in the context of wireless in-vehicle IP-based audio and video communication. We determine the most appropriate transport protocol and discuss its benefits for an application in the car. The analyses are accomplished based on the IEEE 802.11 standard. A testbed is used to measure and compare quality of service values such as throughput, jitter and media quality at the receiver. In the experiments, the traditional protocols TCP and UDP showed the best performance.

A vision for the in-car network

A universal and barrier-free in-car network in which all ECUs are connected with one another through an overall network: this is the task. BMW aims to address this challenge with a convergence layer for communications throughout the car. To this end, the Internet Protocol (IP) is particularly well suited as a common basis for in-car communication. In order to demonstrate the theory in practice, BMW Forschung und Technik GmbH assembled a test vehicle (BMW 530d), fitted with an IP-based in-car network. Both entertainment and driver assistance applications and real-time communications applications were connected using IP.

Vision für das Bordnetz

Ein universelles und barrierefreies Bordnetzes, in dem alle Steuergerate uber ein einheitliches Netzwerk mitei nander verbunden sind, lautet das Ziel. Die BMW Group will dies auf Basis des Internet-Protokolls (IP) als einheitlichem Kommunikationsstandard realisieren. Fur den praktischen Nachweis wurde bei der BMW Forschung und Technik GmbH ein Versuchsfahrzeug auf Basis eines BMW 530d mit einem IP-basierten Bordnetz aufgebaut. Dabei wurden sowohl Applikationen aus den Bereichen Entertainment, Fahrerassistenzsysteme als auch aus dem Bereich Echtzeitkommunikation auf IP umgesetzt.