Day 3 - 24 July
- Sara Faour
Networking protocols and architectures for IIoT and Cyber Physical Systems
Prof. Stefano Giordano
We cannot use the telephone network also for computers network because we need to move from analog to digital. We moved circuit switching (electro-mechanical switching) to packet switching (by software), circuit switching is the best when we have constant bit rate source.
However, computer to computer communication is variable bit rate source, we have peaks and the average data rate is low, from here comes the need for packets switching.
Time Division Multiplexing (TDM) is not adaptive since slots are allocated even for silent transmission.
Telephony communication doesn’t have constant bit rate, for this reason later on, digitization started where silence is not transmitted. This came 60 years later using Voice over IP (VoIP).
Frequency Division Multiplexing (FDM) introduces the statistical multiplexing where silence is not transmitted → more adaptive (but it guarantee no reliability).
However, behind this scheme there is the problem of congestion.
Internet never provide end-to-end QoS, since configuring routers to guarantee QoS is much harder.
For this reason 90% of traffic over Internet are managed by TCP (enabling re-transmission), only 10% use UDP.
Connecting computers introduced three main services: sharing files, sending emails, remote control. But these services were considered useless until internet browser was invented because nobody wanted the service to be stacked to the operating system.
The internet is the virtualization, it is the way of moving the containers which are the IP packets, there is no technology → we cannot compare 5g and internet.
IP on everything and everything over IP
“IP on everything” is true, however “everything over IP” is not true, some applications require strict quality of service. TCP/IP can be avoided in many application.
Now the Internet has 8000 protocols (ICMP, SIP, SNMP…)
The Internet is one global infrastructure, using the terms Internet of Drones, Internet of Senses… is counter the philosophy.
Smart dust by prof Kristofer Pister → wireless sensor, but it is more than that, so the best name is “motes”.
The challenge of integration: reliability, security, performances (including power consumption) → arises when we have compound applications.
Software Defined Networking (SDN)
Key aspects of the paradigm shift in telecommunications:
Open
Programmable
Virtualized
Data Driven
Autonomous
Self-healing
Network Agility and Policies:
Network agility can be defined as the speed at which a network can adapt to change while maintaining
resiliency, security, and management simplicity.Network policy is a collection of rules that govern the behaviors of network devices.
Tactile Internet: A network or network of networks for remotely accessing, perceiving, manipulating or
controlling real or virtual objects or processes in perceived real time by humans or machines.
One of the good points of Lora is the ability to configure a spreading function.
Web of Things: architectures, protocols and platforms for IoT applications
Prof. Enzo Mingozzi
Outline:
Vertical vs. horizontal solutions
Web of Things
CoAP protocol
MQTT
Data interoperability
IoT platforms
IoT vertical solutions:
The different about smart grids is that energy cannot be stored and delivered, it should be delivered immediately.
Smart meters work on controlling the non-essential load to fit the overall generation profile.
Different vertical solutions:
smart grid
smart metering
smart home
smart thermostats
connected E-health
smart cities
smart parking
payment for EV charging
IoT horizontal solutions:
where interoperability can be achieved through IoT platform and IoT network standards!
but also new challenges
• Scale
– Number of nodes in the system
– Amount of data generated by each node
• Diversity of applications
• Diversity of communication technologies
– Potentially lossy if wireless
• Interoperability
• Low-power consumption
• Lifetime
• Cross-layer optimization
• Location-awareness
Web of Things offers the solution for horizontal solutions
How to achieve interoperability?
IPv6 based solutions:
• IETF (6LowPAN, RPL, 6Lo, …)
– Supported by the IPSO Alliance (now part of the OMA SpecWorks)
• Thread Open Standard
World Wide Web
Identification: A Uniform Resource Identifier (URI) “is a compact string of characters for identifying an abstract or physical resource”. It can be a name or an address.
Data exchange: Hypertext Transfer Protocol (HTTP) “… is an application-level protocol for distributed,
collaborative, hypermedia information systems”.
Data encoding: HyperText Markup Language (HTML), HTML is ok for data presentation but Not ok for application data encoding → XML is suitable
Constrained Application Protocol (CoAP)
Reliability is optional, CoAP Async Messages is available to offer a simplified TCP instead of UDP if needed.
CoAP Request/Response has the same model as HTTP (client/server)
The smallest CoAP message can be as small as 4 bytes.
Message Queue Telemetry Transport (MQTT): not suitable for constrained devices.
senml: sensor xml
JSON: Lightweight data encoding → less flexible than XML
CBOR: Binary encoding