RFIoT Stack vs. Web Stack: A Detailed Comparison
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This article compares the IoT (Internet of Things) stack with the Web stack, highlighting their key differences in functionalities across various layers. To begin, let’s briefly review the OSI and TCP/IP models.
Understanding the OSI and TCP/IP Models
As shown in Figure 1, the OSI (Open Systems Interconnection) model consists of 7 layers, while the TCP/IP model has 4 layers. Understanding the basic functions of each of the 7 OSI layers (from top to bottom) is crucial. These layers exist on both the transmit and receive sides of a networking device, enabling two-way communication.
Figure 1: OSI stack vs TCPIP stack
Here’s a summary of each OSI layer:
- Application Layer: This is where data originates from applications like web browsers, FTP clients, and Telnet. The data can be in various formats (binary, ASCII, EBCDIC, etc.).
- Presentation Layer: Handles syntax conversion (e.g., binary to ASCII) and encryption/decryption of data.
- Session Layer: Manages sessions, which is useful for billing purposes by operators.
- Transport Layer: Provides flow control, fragmentation, and reassembly of data for transmission or reception.
- Network Layer: Responsible for routing packets based on logical addressing (IPv4 and IPv6). Routing protocols like RIP, OSPF, and AODV operate at this layer.
- Data Link Layer: Handles error control and flow control, including retransmission of faulty packets using ARQ (Automatic Repeat Request). This layer also manages medium access control for wired or wireless physical layer interfaces (MAC layer).
- Physical Layer: Transmits data over the physical medium (wired or wireless). This layer includes functionalities like modulation/demodulation and FEC (Forward Error Correction). Advanced modulation schemes (OFDM, OFDMA) can be used for high data rates. Common FEC modules include convolution encoders (Tx) and Viterbi decoders (Rx).
IoT Stack vs. Web Stack: A Layer-by-Layer Comparison
Figure 2 illustrates the IoT stack compared to the Web stack. The table below details the differences between the IoT stack and the Web stack, focusing on the functionalities at each layer. Note that the Physical and MAC layers in the IoT stack vary depending on the specific wired or wireless technologies used.
Figure 2: IoT Stack vs Web Stack
| Feature | IoT Stack | Web Stack |
|---|---|---|
| Function/Application | Used in constrained networks with low power, low bandwidth, and low memory requirements. | Used in non-constrained networks with no limits on power, bandwidth, or memory. |
| Data Size | Tens of bytes. | Hundreds or thousands of bytes. |
| Data Format | Uses CBOR (Concise Binary Object Representation) for tiny messages. CBOR is based on JSON but employs binary encoding, while JSON uses text encoding. | Uses HTML, XML, and JSON formats. |
| Application Layer | Uses CoAP (Constrained Application Protocol). | Uses HTTP (Hypertext Transfer Protocol). |
| Transport Layer | Uses UDP (User Datagram Protocol), which is faster due to its smaller header size compared to TCP. It’s a lighter protocol than TCP. | Uses TCP (Transmission Control Protocol), which is connection-oriented and slower compared to UDP. |
| Security Layer | Uses DTLS (Datagram Transport Layer Security) for security. | Uses TLS/SSL (Transport Layer Security/Secure Sockets Layer) protocols for security. |
| Internet Layer | Uses 6LoWPAN (IPv6 over Low-Power Wireless Personal Area Networks) to convert large IPv6 packets into smaller sizes for wireless transmission (Bluetooth, Zigbee, etc.). Performs fragmentation and reassembly and header compression. | Does not require protocols like 6LoWPAN. Fragmentation and reassembly are handled by the Transport layer (TCP). |
| Data Link/MAC Layer | MAC layer varies based on the IoT wireless technology (Bluetooth, Zigbee, Z-Wave, etc.). It manages medium access control, resource allocation, and management. | MAC layer varies based on the network technology (LAN, WLAN, DSL, ISDN). |
| Physical/RF Layer | Physical layer (baseband) varies based on the IoT wireless technology (Bluetooth, Zigbee, Z-Wave, etc.). Uses frequencies according to cellular or indoor wireless technologies and country-wide allocations. | Physical layer varies based on the network technology (LAN, WLAN, DSL, ISDN). |
