Jörg Sommer

Ethernet – A Survey on its Fields of Application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application fields requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal.

Optimized Resource Dimensioning in an embedded CAN-CAN Gateway

The Controller Area Network (CAN) is a robust, low-cost, and simple event-triggered technology for connecting electronic control units in the manufacturing industry and vehicles. Todays real-time control systems are distributed over a multitude of CAN systems (domains) which are connected via embedded gateways. A failure or overload situation in the gateway can affect several domains. Furthermore, gateways often become bottlenecks between the domains and in the case of CAN buses they can pose further problems with respect to the priority-based network access method. Due to this access method and the limited resources (e.g., buffer capacity) embedded CANCAN gateways have to be dimensioned accurately. Otherwise, unacceptable processing delay and message loss within the gateway can occur. The main contribution of this paper is to investigate the optimized dimensioning of an embedded CAN-CAN gateway with regard to minimizing gateway resources in terms of processing and buffer capacity and decreasing message loss at the same time. For that purpose a CAN bus and a gateway model are described and used to investigate scenarios with two domains connected via a gateway.

IKR Simulation Library

The Simulation Library (SimLib) of the Institute of Communication Networks and Computer Engineering (IKR) [216] at the University of Stuttgart is a tool for event-driven simulation of complex systems in the area of communications engineering. The first version of the IKR SimLib was implemented in Pascal in the 1980s. Later in 1993, during his dissertation [256] Hartmut Kocher redesigned the Pascal simulation library and developed an objectoriented class library of the IKR SimLib in C++.

On link harness optimization of embedded Ethernet networks

During the last decades, Ethernet progressively became the most widely used Local Area Network (LAN) technology. It evolved from a bus topology to a micro-segmented network with full duplex links. Apart from LAN installations, Ethernet became also attractive for embedded application areas such as industrial, automotive, and avionics. In these areas, the connectivity between the nodes and the switches results in link harnesses. These harnesses can be bundled together and installed inside ducts. Since not all the links have the same endpoints, some full duplex links leave a duct at points referred to as junction points. In this paper, we propose a Simulated Annealing based algorithm to optimize the topology design of embedded Ethernet networks. This algorithm finds the (near-)optimal positions of a given number of switches and their connections to given nodes. When we take into account that links are organized into link harnesses and installed into ducts, we have to find also the number of junction points required as well as their optimal positions. For this purpose, we propose two algorithms. Finally, we compare the algorithms in terms of computation time and the quality of the obtained solution, and we highlight the cost benefits of bundling links and installing them into ducts.

Optimized Frame Packing for OFDMA Systems

Orthogonal frequency division multiple access (OFDMA) is the basis for several emerging wireless systems, such as 802.16e (WiMAX) or 3GPP long term evolution (LTE). In OFDMA, different users are multiplexed in time and frequency. In the 802.16e adaptive modulation and coding (AMC) downlink, the data bursts for a particular terminal have a rectangular shape and need to be placed in the two-dimensional time/frequency plane. The position and shape of the rectangles is arbitrary, and it is the task of the frame packer to pack the frame efficiently, wasting as little space as possible. In this paper, we treat the frame packing problem as a strip-packing problem. We solve this combinatorial optimization problem by developing a suitable representation for a genetic algorithm. This algorithm can reach within 5% of the theoretical lower bound for the packing efficiency.

Cost-Based Topology Optimization of Embedded Ethernet Networks

During past decades, Ethernet progressively became the most widely used Local Area Network LAN technology. Apart from LAN installations, Ethernet also became attractive for other application areas such as industrial control, automotive, and avionics. In traditional LAN design, the objective is to minimize the network deployment cost. However, in embedded networks, additional constraints and ambient conditions add to the complexity of the problem. In this paper, the authors propose a Simulated Annealing SA algorithm to optimize the physical topology of an embedded Ethernet network. The various constraints and ambient conditions are modeled by a cost map. For networks with small number of nodes and/or switches, the authors were able to find the optimal solutions using adapted algorithms. These solutions will serve as a lower bound for the solutions obtained via the SA algorithm. However, the adapted algorithms are time consuming and application specific. The paper shows that the SA algorithm can be applied in all cases and finds near-optimal solutions.

On optimal communication spanning trees in embedded Ethernet networks

In network design, the Optimal Communication Spanning Tree (OCST) problem is to find a spanning tree that connects the network entities and satisfies their communication requirements with minimal total cost. In an embedded Ethernet network, we organize the full duplex links into bundles and install these bundles into ducts. The traditional OCST problem does not take into account this fact. In this paper, we introduce a mathematical model of the communication cost of an embedded Ethernet network. We propose novel algorithms to find an OCST. Their principle idea is that they iteratively examine a set of neighboring trees that differ in one duct and choose the tree with the lowest cost. Finally, we evaluate the performance of the algorithms in terms of the quality of the solution found as well as the running time.

Scheduling Algorithms for Simultaneous Software Updates of Electronic Devices in Vehicles

Todays upper-class passenger cars have various interconnected electronic devices. Each device performs complex functions, enabled by software that can be stored in a flash memory. Of these, the devices in the multimedia and infotainment domain contain by far the most software with a size in the order of one Gbyte. In this domain, the devices are the performance bottlenecks, not the communication systems. Throughout the vehicle life cycle, parts of the software have to be frequently updated during maintenance. Today, the software of the devices is updated in a consecutive manner. Due to performance bottlenecks caused by the affected devices, the update can take a long time that leads to high costs. Therefore, the objective is to reduce the total update time by a higher utilization of the common bus resource. In this paper, we introduce and investigate algorithms that update the software of multiple devices simultaneously and evaluate the efficiency of these algorithms. We focus on scheduling algorithms on the Application layer and the logical link control (LLC) layer and model the update process by means of Petri nets. Our studies show that it is most promising to combine a simple scheduling algorithm on the Application layer with Round Robin on the LLC layer.