1. Physical cum Data-Link Layer (Layer 1 & 2) – Gathering Data
This is the foundation of IoT communication, where data is physically transmitted between devices.
Key Functions:
- Physical layer: Handles hardware connections like wired (Ethernet, Fiber Optic) or wireless (Wi-Fi, Bluetooth, Zigbee, LoRa, 5G).
- Data-Link layer: Ensures reliable point-to-point communication using MAC (Media Access Control) and LLC (Logical Link Control).
Example: Sensors detecting temperature and sending raw data over Zigbee.
2. Data Adaptation Layer (Layer 2) – Enriching Data
This layer refines raw data before it moves up the network.
Key Functions:
- Converts different data formats for compatibility.
- Adds error detection and correction mechanisms.
- Handles device addressing via MAC addresses.
Example: A smart meter adapts electrical readings to a suitable format for transmission.
3. Network Layer (Layer 3) – Routing Data
This layer is responsible for determining the best path for data transmission across networks.
Key Functions:
- Assigns IP addresses to IoT devices.
- Uses routing protocols (IPv6, MQTT, CoAP) for efficient data delivery.
- Ensures data reaches the correct cloud server or gateway.
Example: A smart irrigation system sends soil moisture data to a cloud server via a Wi-Fi router.
4. Transport Layer (Layer 4) – Streaming Data
This layer ensures secure and reliable data transmission between IoT devices and cloud platforms.
Key Functions:
- Provides error control & retransmission if data is lost.
- Uses TCP (Transmission Control Protocol) for reliability.
- Uses UDP (User Datagram Protocol) for real-time, low-latency communication.
Example: A live video stream from a security camera uses UDP for low-latency streaming.
5. Session Layer (Layer 5) – Managing Connections
This layer establishes, maintains, and terminates communication sessions between IoT devices.
Key Functions:
- Synchronizes multiple data streams.
- Manages authentication and re-connection in case of failures.
Example: A smart home assistant (like Alexa) maintains a session with a cloud service while processing voice commands.
6. Presentation Layer (Layer 6) – Formatting and Securing Data
This layer translates data into a readable format and ensures security.
Key Functions:
- Converts data between different formats (JSON, XML, binary).
- Implements encryption (TLS/SSL) for secure transmission.
- Compresses data for efficient transfer.
Example: A smart fridge encrypts temperature logs before sending them to the cloud.
7. Application Layer (Layer 7) – Managing IoT Applications & Services
This is the topmost layer where users interact with IoT applications through web dashboards or mobile apps.
Key Functions:
- Data acquisition, storage, and analytics.
- Provides interfaces (REST APIs, MQTT brokers) for developers.
- Displays insights on dashboards or mobile apps.
Example: A smart city traffic management system collects real-time traffic data and shows it on a dashboard for city planners.
Summary:
| Layer | Function | Example |
|---|---|---|
| Physical cum Data-Link | Sensing and transmitting raw data | Temperature sensors |
| Data Adaptation | Formatting and refining data | Error correction in sensor data |
| Network | Routing and IP addressing | Sending data via Wi-Fi or LPWAN |
| Transport | Ensuring reliable transmission | Secure data exchange with TCP/UDP |
| Session | Managing connections | Smart assistant interactions |
| Presentation | Data security and conversion | Encryption for IoT data |
| Application | Providing insights and control | IoT dashboards & mobile apps |
Design Standardization
Standardization ensures consistency, security, and compatibility in IoT/M2M systems. Key standardization bodies, frameworks, and protocols include:
International Standards
ISO/IEC 30141 – IoT Reference Architecture.
IEEE P2413 – IoT Architectural Framework.
ITU-T Y.2060 – Overview of IoT and its framework.
ISO/IEC 30141 – IoT Reference Architecture.
IEEE P2413 – IoT Architectural Framework.
ITU-T Y.2060 – Overview of IoT and its framework.
Communication Protocols
MQTT (Message Queuing Telemetry Transport) – Lightweight messaging protocol for IoT.
CoAP (Constrained Application Protocol) – Web-based communication for constrained devices.
HTTP/HTTPS – Standard protocols for web-based IoT applications.
DDS (Data Distribution Service) – High-performance real-time communication for industrial IoT.
AMQP (Advanced Message Queuing Protocol) – Middleware messaging for IoT applications.
MQTT (Message Queuing Telemetry Transport) – Lightweight messaging protocol for IoT.
CoAP (Constrained Application Protocol) – Web-based communication for constrained devices.
HTTP/HTTPS – Standard protocols for web-based IoT applications.
DDS (Data Distribution Service) – High-performance real-time communication for industrial IoT.
AMQP (Advanced Message Queuing Protocol) – Middleware messaging for IoT applications.
Wireless Connectivity Standards
Zigbee and Z-Wave – Wireless communication standards for smart home devices.
LoRaWAN and NB-IoT – Low-power, wide-area network (LPWAN) protocols for IoT connectivity.
5G and LTE-M – Cellular network standards for high-speed IoT applications.
Wi-Fi HaLow (802.11ah) – Low-power Wi-Fi standard for IoT devices.
Zigbee and Z-Wave – Wireless communication standards for smart home devices.
LoRaWAN and NB-IoT – Low-power, wide-area network (LPWAN) protocols for IoT connectivity.
5G and LTE-M – Cellular network standards for high-speed IoT applications.
Wi-Fi HaLow (802.11ah) – Low-power Wi-Fi standard for IoT devices.
Industrial and Security Standards
OPC UA (Open Platform Communications Unified Architecture) – Standard for industrial IoT (IIoT) communication.
NIST Cybersecurity Framework – Guidelines for securing IoT devices.
IEC 62443 – Industrial cybersecurity framework for IoT and M2M.
FIDO (Fast Identity Online) – Authentication standard for IoT security.
OPC UA (Open Platform Communications Unified Architecture) – Standard for industrial IoT (IIoT) communication.
NIST Cybersecurity Framework – Guidelines for securing IoT devices.
IEC 62443 – Industrial cybersecurity framework for IoT and M2M.
FIDO (Fast Identity Online) – Authentication standard for IoT security.
Middleware and Edge Computing Frameworks
OneM2M – Common service layer for M2M communication.
EdgeX Foundry – Open-source framework for edge computing in IoT.
OpenFog Consortium – Fog computing architecture for IoT.
OneM2M – Common service layer for M2M communication.
EdgeX Foundry – Open-source framework for edge computing in IoT.
OpenFog Consortium – Fog computing architecture for IoT.
By adhering to these standards, IoT systems achieve better security, interoperability, scalability, and reliability, ensuring seamless integration across diverse devices and platforms.