72 research outputs found
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 field’s 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
Evaluation of IEEE 802.1 Time Sensitive Networking Performance for Microgrid and Smart Grid Power System Applications
Proliferation of distributed energy resources and the importance of smart energy management has led to increased interest in microgrids. A microgrid is an area of the grid that can be disconnected and operated independently from the main grid when required and can generate some or all of its own energy needs with distributed energy resources and battery storage. This allows for the microgrid area to continue operating even when the main grid is unavailable. In addition, often a microgrid can utilize waste heat from energy generation to drive thermal loads, further improving energy utilization. This leads to increased reliability and overall efficiency in the microgrid area.As microgrids (and by extension the smart grid) become more widespread, new methods of communication and control are required to aid in management of many different distributed entities. One such communication architecture that may prove useful is the set of IEEE 802.1 Time Sensitive Networking (TSN) standards. These standards specify improvements and new capabilities for LAN based communication networks that previously made them unsuitable for widespread deployment in a power system setting. These standards include specifications for low latency guarantees, clock synchronization, data frame redundancy, and centralized system administration. These capabilities were previously available on proprietary or application specific solutions. However, they will now be available as part of the Ethernet standard, enabling backwards compatibility with existing network architecture and support with future advances.Two of the featured standards, IEEE 802.1AS (governing time-synchronization) and IEEE 802.1Qbv (governing time aware traffic shaping), will be tested and evaluated for their potential utility in power systems and microgrid applications. These tests will measure the latency achievable using TSN over a network at various levels of congestion and compare these results with UDP and TCP protocols. In addition, the ability to use synchronized clocks to generate waveforms for microgrid inverter synchronization will be explored
Design of a New High Bandwidth Network for Agricultural Machines
Ethernet is by now the most adopted bus for fast digital communications in many environments, from household entertainment to PLC robotics in industrial assembly lines. Even in automotive industry, the interest in this technology is increasingly growing, pushed forward by research and by the need of high throughput that high dynamics distributed control demands. Although 100base-TX physical layer (PHY) does not seem to meet EMC requirements for vehicular and heavy-duty environments, OPEN Alliance BroadR Reach (soon becoming IEEE standard as IEEE 802.3bw) technology is the most promising and already adopted Ethernet-compatible PHY, reaching 100Mbps over an unshielded twisted pair.
An agricultural machine is usually a system including tractor and one or more implements attached to it, to the back or to the front. Nowadays, a specific CAN-based distributed control network support treatments and applications, namely ISOBUS, defined by ISO 11783.
This work deals with architectural and technological aspects of advanced Ethernet networks in order to provide a high-throughput deterministic network for in-vehicle distributed control for agricultural machinery. Two main paths of investigation will be presented: one concerning the prioritization of standard Ethernet taking advantage of standard ways of prioritization in well-established technologies; the other changing the channel access method of Ethernet using an industrial fieldbus, chosen after careful investigation.
The prioritization of standard Ethernet is performed at two, non-mutual exclusive layers of the ISO OSI stack: one at L3, using the diffserv (former TOS) Ip field; one at L2, using the priorities defined in IEEE 802.1p, used in IEEE 802.1q (VLAN). These choices have several implications in the specific field of application of the agricultural machines.
The change of the access method, instead, focused on the adoption of a specific fieldbus, in order to grant deterministic access to the medium and reliability of communications for safety-relevant applications. After a survey, that will be reported, the Powerlink fieldbus was chosen and some modifications will be discussed in order to suit the scope of the research
A Survey of Scheduling in Time-Sensitive Networking (TSN)
TSN is an enhancement of Ethernet which provides various mechanisms for
real-time communication. Time-triggered (TT) traffic represents periodic data
streams with strict real-time requirements. Amongst others, TSN supports
scheduled transmission of TT streams, i.e., the transmission of their packets
by edge nodes is coordinated in such a way that none or very little queuing
delay occurs in intermediate nodes. TSN supports multiple priority queues per
egress port. The TAS uses so-called gates to explicitly allow and block these
queues for transmission on a short periodic timescale. The TAS is utilized to
protect scheduled traffic from other traffic to minimize its queuing delay. In
this work, we consider scheduling in TSN which comprises the computation of
periodic transmission instants at edge nodes and the periodic opening and
closing of queue gates.
In this paper, we first give a brief overview of TSN features and standards.
We state the TSN scheduling problem and explain common extensions which also
include optimization problems. We review scheduling and optimization methods
that have been used in this context. Then, the contribution of currently
available research work is surveyed. We extract and compile optimization
objectives, solved problem instances, and evaluation results. Research domains
are identified, and specific contributions are analyzed. Finally, we discuss
potential research directions and open problems.Comment: 34 pages, 19 figures, 9 tables 110 reference
Time-Sensitive Networking for Industrial Automation: Challenges, Opportunities, and Directions
With the introduction of Cyber-Physical Systems (CPS) and Internet of Things
(IoT) into industrial applications, industrial automation is undergoing
tremendous change, especially with regard to improving efficiency and reducing
the cost of products. Industrial automation applications are often required to
transmit time- and safety-critical data to monitor and control industrial
processes, especially for critical control systems. There are a number of
solutions to meet these requirements (e.g., priority-based real-time schedules
and closed-loop feedback control systems). However, due to their different
processing capabilities (e.g., in the end devices and network switches),
different vendors may come out with distinct solutions, and this makes the
large-scale integration of devices from different vendors difficult or
impossible. IEEE 802.1 Time-Sensitive Networking (TSN) is a standardization
group formed to enhance and optimize the IEEE 802.1 network standards,
especially for Ethernet-based networks. These solutions can be evolved and
adapted into a cross-industry scenario, such as a large-scale distributed
industrial plant, which requires multiple industrial entities working
collaboratively. This paper provides a comprehensive review on the current
advances in TSN standards for industrial automation. We present the
state-of-the-art IEEE TSN standards and discuss the opportunities and
challenges when integrating each protocol into the industry domains. Finally,
we discuss some promising research about applying the TSN technology to
industrial automation applications
EDGAR: An Autonomous Driving Research Platform -- From Feature Development to Real-World Application
While current research and development of autonomous driving primarily
focuses on developing new features and algorithms, the transfer from isolated
software components into an entire software stack has been covered sparsely.
Besides that, due to the complexity of autonomous software stacks and public
road traffic, the optimal validation of entire stacks is an open research
problem. Our paper targets these two aspects. We present our autonomous
research vehicle EDGAR and its digital twin, a detailed virtual duplication of
the vehicle. While the vehicle's setup is closely related to the state of the
art, its virtual duplication is a valuable contribution as it is crucial for a
consistent validation process from simulation to real-world tests. In addition,
different development teams can work with the same model, making integration
and testing of the software stacks much easier, significantly accelerating the
development process. The real and virtual vehicles are embedded in a
comprehensive development environment, which is also introduced. All parameters
of the digital twin are provided open-source at
https://github.com/TUMFTM/edgar_digital_twin
Sub-Microsecond Time Synchronization for Network-Connected Microcontrollers
This paper presents a bare-metal implementation of the IEEE 1588 Precision Time Protocol (PTP) for network-connected microcontroller edge devices, enabling sub-microsecond time synchronization in automotive networks and multimedia applications. The implementation leverages the hardware timestamping capabilities of the microcontroller (MCU) to implement a two-stage Phase-locked loop (PLL) for offset and drift correction of the hardware clock. Using the MCU platform as a PTP master enables the distribution of a sub-microsecond accurate Global Positioning System (GPS) timing signal over a network. The performance of the system is evaluated using master-slave configurations where the platform is synchronized with a GPS, an embedded platform, and a microcontroller master. Results show that MCU platforms can be synchronized to an external GPS reference over a network with a standard deviation of 40.7 nanoseconds, enabling precise time synchronization for bare-metal microcontroller systems in various applications
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