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Real-Time Communication - Industrial
Embedded Systems
Hoai Hoang, Magnus Jonsson
School of Information Science, Computer and Electrical
Engineering, Halmstad University, Sweden
Problem statement

Embedded systems
become more complex

Increase the demand on
heterogeneity, QoS

Low down the cost:
installation, maintenance
Switch Real-Time Ethernet for Industrial Applications
ERIEYE radar system (EMW)
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Main research's goals

Developing Real-time services over System
Area Networks using Switch Ethernet

Support special traffic pattern for embedded
system

Find the communication solution:
 Meet real-time demand
 Guarantee network’s performances
Switch Real-Time Ethernet for Industrial Applications
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Project overview

Using pure switched base network
 Increase heterogeneity, performance...

Support time-critical applications
 Focus on real-time service in industrial and
embedded system.
 Provide both real-time and non-real-time traffic
Switch Real-Time Ethernet for Industrial Applications
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Related work
End-node
Application and
application protocols
UDP
Switch
TCP
Real-time traffic handling
RT channel management
1
3
IP
4
2
5
RT layer
RT layer
Ethernet MAC
(and LLC)
MAC
Ethernet PHY
PHY
Coordination of
many-to-many
communication etc
Switched Full-Duplex Real-Time Ethernet Network
Switch Real-Time Ethernet for Industrial Applications
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Previous result

Proposed method for
distribution end-to-end
deadline for messages

Improve network
performances special
master-slave
communication
Switch Real-Time Ethernet for Industrial Applications
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Previous result
75 % more channels using asymmetric deadline partitioning for a network
with 10 master nodes and 50 slave nodes. Each channel i is characterized
by Ci=3, Pi=100, Di=40
Switch Real-Time Ethernet for Industrial Applications
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Real-time over WANs

Extend the network
topology
 More switches in the
network
 Multihop network

Switch Real-Time Ethernet for Industrial Applications
Guarantee real-time
communication over
WANs
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Real-time over WANs
Sender, Receiver
Deadline (relative):
 End-to-End (D)
 Node-to-Node (Dj)
 Minimum (minDj)
The RTC feasible If
D   minD j
Switch Real-Time Ethernet for Industrial Applications
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Real-time over WANs
Slack can occur
 minD
j
 D  Slack
Question: What the system do with the slack?
Switch Real-Time Ethernet for Industrial Applications
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Real-time over WANs
Ferrari and Verma: Divide it equally between the
Node-to-Node deadlines of the channel:
1
Dk  minDk  Slack
N
We divide it such that links with a history of
“demanding traffic” gets more:
wk
Dk  minDk 
Slack
 wj
Switch Real-Time Ethernet for Industrial Applications
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Real-time over WANs
We want to see if our approach is better, in the
sense that more real-time traffic can be feasible
schedule.
For what kind of topologies?
Under what kind of traffic patterns?
Switch Real-Time Ethernet for Industrial Applications
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Real-time over SAN - Future works
Real-time services
• Normal data exchange
• Synchronization of software
processes
• Real-time debugging
• Clock synchronization
• Group communication (many-tomany etc)
• etc
Emerging SAN (and LAN)
standards
Single real-time
multi-service SAN
in each application
Problem: The SAN standards do not deliver this real-time multi-service
functionality as is. At the same time the industry has to cope with complex
designs, high engineer efforts and high product costs when forced to use
several service-specific networks in the same application.
Switch Real-Time Ethernet for Industrial Applications
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Real-time over SAN - Future works
Heterogeneous communication
 Heterogeneous network
 Heterogeneous services
Example: Radar signal processing systems
Control traffic, periodic with a master-slave pattern and
delay-bound
Data traffic (radar data), periodic with a very high bitrate and a partially pipelined data flow. Probabilistically
guaranteed delay-bound
Other non-real-time traffic
Switch Real-Time Ethernet for Industrial Applications
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