L1 Flashcards
What is IoT?
Combination of internet and things
Internet: a mean for global networking nodes
Things: sensors or nodes transmitting/exchanging data
Knowledge fields involved in IoT
- Signal processing
- RF engineering
- Embedded systems
- Wireless networks
- Communication systems
- Sensors and actuators
Some IoT applications
- Robotics
- Autonomous vehicles
- Micro payments
- Smart grids
- Agriculture
Main components of wireless sensor network and draw schematic (L1 pag 14)
- Sensor nodes
- Base stations: needed as we cannot send all data from the nodes at once
- Internet: analysis, storage, mining, processing
Objectives of designing WSNs
- small node size
- low node cost
- lower power consumption
- network protocol scalability
- reliability and fault-tolerance
- security
- good channel bandwidth utilization
The seven layers of reference model architecture
- Application layer: user writes message
- Presentation layer: message converter to ASCII
- Session layer: security layer is added
- Transport layer
- Network layer: routing and addressing
- Data-link layer: splits message into packets
- Physical layer
*After physical layer message is ready to be sent through physical medium
*When message is received, same layer occurs in reversed direction - Every communication must pass through these layers
What is added to the message at each layer?
Each layer adds its own header
Properties of OSI mode (L1 pag 21)
read pdf
Common issues of OSI model principles
- Addressing
- Segmentation
- Fragmentation
Layer into which Data link layer can be subdivided
- Data link control sub-layer
- Medium access control sub-layer
4 layer of TCP/IP model (OSI equivalent layer)
- Application layer (application, presentation, and session layers)
- Transport layer
- Internet layer (network layer)
- Network-access layer (Data-link layer, physical layer)
Is internet a communication layer? (L1 pag 27)
No, it’s a networking layer.
Characteristics of physical layer
- provides electrical means for establishing physical connection for data transmission
- signal transmission: analog or digital
- voltage levels represent logical signal levels 0 or 1
Physical medium types
- Guided: coaxial cable, optical fiber
- Free space: radio wave, THz
Data link layer properties
- constructs data frame using appropriate format for the network
- detects/corrects errors occurred at physical layer
- provides multiple access (time or frequency domain) and channel assignment
Network layer properties
- determines best route for data packets
- provides means to establish, maintain and terminate network connections between open systems
Transport layer properties
- Ensures reliable data packet transmission from node to node
- ensures data is sent/received in the same order
- acknowledges when data is received
- resend packets in case of error
session layer functions
- initiates communication link
- assures reliable communication between transmitting and receiving nose
- decides timing sequences between both nodes
Presentation layer functions
- assures proper data formatting for receiving node to understand
- carries out important data encryption and decryption
- performs data compression and decompression
application layer functions
- handles end-user services and applications
