157  IoT Communications Technology

157.1 Learning Objectives

By the end of this chapter, you will be able to:

  • Classify Network Types: Distinguish between PAN, LAN, MAN, and WAN network classifications and their IoT applications
  • Evaluate Communication Technologies: Compare protocols like Bluetooth LE, Zigbee, Wi-Fi, LoRaWAN, and cellular based on range, power, and data rate
  • Match Technologies to Applications: Select appropriate communication technologies for specific IoT verticals
  • Understand UART: Explain how UART serial communication works and its role in IoT device interfaces
NoteKey Concepts
  • Personal Area Network (PAN): Short-range networks (up to 10 meters) for wearables and personal devices using Bluetooth, Zigbee, NFC
  • Local Area Network (LAN): Medium-range networks (up to 100 meters) for homes and offices using Wi-Fi and Ethernet
  • Metropolitan Area Network (MAN): Wide-range networks (up to several kilometers) for cities using LoRaWAN and NB-IoT
  • Wide Area Network (WAN): Very wide-range networks (thousands of kilometers) using cellular and satellite
  • UART: Universal Asynchronous Receiver-Transmitter, a fundamental hardware protocol for serial communication between microcontrollers and peripherals

157.2 Prerequisites

Before diving into this chapter, you should be familiar with:

NoteChapter Position in Series

This is the second chapter in the Architectural Enablers series:

  1. IoT Evolution and Enablers Overview - History and convergence
  2. IoT Communications Technology (this chapter) - Protocols and network types
  3. Technology Selection and Energy - Decision frameworks
  4. Labs and Assessment - Hands-on practice

157.3 Communications Technology Overview

~18 min | Intermediate | P04.C08.U08

Communication technologies are critical to the functioning of IoT systems. They enable the connectivity and data exchange between IoT devices, ensuring that information flows smoothly from sensors and devices to data processing units and end-users.

157.3.1 Personal Area Networks (PAN)

  • Examples: Bluetooth, Zigbee, NFC, Z-Wave
  • Range: Short (up to 10 meters)
  • Data Rate: Low to moderate
  • Power Consumption: Low
  • Applications: Wearable devices, home automation, personal health monitoring

157.3.2 Local Area Networks (LAN)

  • Examples: Wi-Fi, Ethernet, Powerline communication
  • Range: Medium (up to 100 meters)
  • Data Rate: High
  • Power Consumption: Moderate to high
  • Applications: Smart homes, offices, building automation

157.3.3 Metropolitan Area Networks (MAN)

  • Examples: LoRaWAN, NB-IoT
  • Range: Wide (up to several kilometers)
  • Data Rate: Low to moderate
  • Power Consumption: Low to moderate
  • Applications: Smart cities, industrial IoT, agriculture

157.3.4 Wide Area Networks (WAN)

  • Examples: Cellular (2G, 3G, 4G, LTE), Satellite
  • Range: Very wide (up to thousands of kilometers)
  • Data Rate: High
  • Power Consumption: High
  • Applications: Connected vehicles, remote monitoring, global asset tracking

157.3.5 Choosing the Right Technology

When selecting a communication technology for an IoT application, several factors must be considered:

  • Range: The distance over which the data needs to be transmitted.
  • Power Consumption: The amount of power the communication module consumes, which affects the battery life of the device.
  • Data Rate: The volume of data that needs to be transmitted within a specific timeframe.
  • Network Topology: The structure of the network, whether it’s a star, mesh, or point-to-point configuration.
  • Cost: The cost of implementing and maintaining the communication technology.
Overview of IoT communication technologies organized by network type: PAN (Bluetooth, Zigbee, NFC with short range), LAN (Wi-Fi, Ethernet with medium range), MAN (LoRaWAN, NB-IoT with city-wide range), and WAN (Cellular, Satellite with global reach), showing data rates, power consumption, and typical applications for each category
Figure 157.1: Communications Technology Overview

157.4 Communication Technologies and Application Domains

Selecting the right communication technology for a specific IoT vertical is crucial to ensure optimal performance, efficiency, and cost-effectiveness. The following table outlines the applicability of various communication technologies across key IoT verticals.

Key IoT Verticals LPWAN (Star) Cellular (Star) Zigbee (Mostly Mesh) BLE (Star & Mesh) Wi-Fi (Star & Mesh) RFID (Point-to-point)
Industrial IoT O O
Smart Meter *
Smart City *
Smart Building * O O
Smart Home * * * O
Wearables O *
Connected Car *
Connected Health *
Smart Retail O * *
Logistics & Asset Tracking O * *
Smart Agriculture *
  • Legend:
    • * Highly applicable
    • O Moderately applicable

157.4.1 LPWAN (Low-Power Wide-Area Network)

  • Highly applicable for Smart Meter, Smart City, Smart Building, and Smart Agriculture.
  • Moderately applicable for Logistics & Asset Tracking.
  • Description: LPWAN is ideal for applications requiring long-range communication with low power consumption. It is particularly suited for large-scale deployments in smart cities and agriculture where devices are dispersed over wide areas.

157.4.2 Cellular

  • Highly applicable for Connected Car.
  • Moderately applicable for Industrial IoT, Wearables, Smart Retail, and Logistics & Asset Tracking.
  • Description: Cellular networks offer extensive coverage and high data rates, making them suitable for mobile and wide-area applications such as connected cars and wearables.

157.4.3 Zigbee

  • Highly applicable for Smart Home and Logistics & Asset Tracking.
  • Moderately applicable for Smart Building.
  • Description: Zigbee’s low power consumption and mesh networking capabilities make it ideal for home automation and asset tracking within buildings.

157.4.4 Bluetooth Low Energy (BLE)

  • Highly applicable for Smart Home, Wearables, Connected Health, and Smart Retail.
  • Description: BLE is designed for low power consumption, making it suitable for devices that require frequent communication but need to conserve battery life, such as health monitors and wearable devices.

157.4.5 Wi-Fi

  • Highly applicable for Smart Home.
  • Moderately applicable for Smart Building.
  • Description: Wi-Fi provides high data rates and is widely available, making it ideal for home automation and smart building applications where power consumption is less of a concern.

157.4.6 RFID

  • Highly applicable for Smart Retail and Logistics & Asset Tracking.
  • Moderately applicable for Industrial IoT and Smart Home.
  • Description: RFID is used for point-to-point communication and is suitable for applications involving tracking and identification of items, such as in logistics and retail environments.

The choice of communication technology in IoT systems should be guided by the specific requirements of the application, such as range, power consumption, data rate, and network topology.

157.5 Universal Asynchronous Receiver-Transmitter (UART)

~10 min | Intermediate | P04.C08.U09

Universal Asynchronous Receiver-Transmitter (UART) is a fundamental hardware communication protocol used in many IoT devices for serial communication between microcontrollers and peripherals. UART enables asynchronous serial communication, meaning data is transmitted without a shared clock signal between the transmitter and receiver.

157.5.1 How UART Works

UART communication uses two wires: - TX (Transmit): Sends data from the device - RX (Receive): Receives data to the device

Both devices must agree on: - Baud rate: Speed of data transmission (e.g., 9600, 115200 bps) - Data bits: Typically 8 bits per frame - Parity: Error checking (none, even, odd) - Stop bits: End-of-frame markers (1 or 2 bits)

157.5.2 UART Frame Structure

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graph LR
    Start[Start Bit<br/>0]
    D0[Data Bit 0]
    D1[Data Bit 1]
    D2[...]
    D7[Data Bit 7]
    Parity[Parity<br/>Optional]
    Stop[Stop Bit<br/>1-2 bits]

    Start --> D0 --> D1 --> D2 --> D7 --> Parity --> Stop

    style Start fill:#E67E22,stroke:#16A085,color:#fff
    style Stop fill:#E67E22,stroke:#16A085,color:#fff
    style Parity fill:#16A085,stroke:#2C3E50,color:#fff
    style D0 fill:#2C3E50,stroke:#16A085,color:#fff
    style D1 fill:#2C3E50,stroke:#16A085,color:#fff
    style D7 fill:#2C3E50,stroke:#16A085,color:#fff

Figure 157.2: UART frame structure showing start bit, data bits, optional parity, and stop bits for asynchronous serial communication 

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sequenceDiagram
    participant TX as Transmitter
    participant RX as Receiver

    Note over TX,RX: Idle State (Line HIGH)

    TX->>RX: Start Bit (LOW)<br/>Signals: New frame begins

    Note over RX: RX starts sampling<br/>at baud rate intervals

    TX->>RX: Bit 0 (LSB)
    TX->>RX: Bit 1
    TX->>RX: ...
    TX->>RX: Bit 7 (MSB)

    TX->>RX: Parity Bit (optional)<br/>Error detection

    TX->>RX: Stop Bit(s) (HIGH)<br/>Frame complete

    Note over TX,RX: Return to Idle<br/>Ready for next byte

    rect rgb(22, 160, 133, 0.1)
    Note over TX,RX: Key: No shared clock!<br/>Both must use same baud rate<br/>(e.g., 115200 bits/sec)
    end

Figure 157.3: Alternative view: Timing sequence diagram showing UART communication flow. Start bit (LOW) signals frame beginning, receiver samples data bits at agreed baud rate, optional parity enables error detection, stop bit (HIGH) marks frame end. No shared clock - both devices must configure identical baud rate for reliable communication.

157.5.3 Advantages of UART

  • Simple two-wire interface (plus ground)
  • Well-established and widely supported
  • No clock signal required
  • Full-duplex communication (simultaneous TX and RX)

157.5.4 Limitations of UART

  • Limited to point-to-point communication
  • No standardized voltage levels (RS-232, TTL, etc.)
  • Maximum distance typically limited to ~15 meters
  • Speed limited by baud rate agreement

UART is commonly used for: - Debugging and logging from microcontrollers - GPS module communication - Bluetooth module interfaces - Sensor data collection - Programming and configuration of IoT devices

157.6 Knowledge Check

Test your understanding of communication technologies.

Question: In UART communication, what is the purpose of the start bit and stop bit(s)?

Explanation: UART (Universal Asynchronous Receiver-Transmitter) has no shared clock signal between devices. Frame structure: 1) Start bit (logic 0): Signals “new data coming” and allows receiver to synchronize to transmitter’s timing, 2) Data bits (5-9 bits): Actual payload, 3) Parity bit (optional): Simple error detection, 4) Stop bit(s) (1-2 bits, logic 1): Marks frame end and provides idle time for receiver. Asynchronous advantage: Only 2 wires (TX, RX) vs. synchronous protocols needing clock signal. Common use: GPS modules, Bluetooth modules, debug consoles. Trade-off: 20-40% overhead from framing bits.

Question: Which network classification (PAN, LAN, MAN, WAN) provides a range of 100m-10km with low-to-moderate power consumption, suitable for campus or city district IoT deployments?

Explanation: Network classifications by range and power: PAN (1-100m, ultra-low power): Bluetooth, Zigbee, Z-Wave - personal/room scale. LAN (10-1000m, moderate power): Wi-Fi, Ethernet - building scale, requires infrastructure every 100m. MAN (100m-10km, low-moderate power): LoRa, WiMAX, LTE-M - city district/campus scale with fewer infrastructure points. WAN (10km+, high power): Cellular, satellite - regional/global scale but high power/cost. Use case match: University campus (2km2) needs MAN (5-10 LoRa gateways) not LAN (100+ Wi-Fi APs) or WAN (expensive cellular).

Question: A smart city deployment needs to cover 50km2 with parking sensors. Each sensor transmits 10 bytes every 5 minutes. Which network topology and protocol minimizes infrastructure cost?

Explanation: LoRaWAN wins for cost: Infrastructure: 3-5 gateways ($300 each) cover 50km2 = $1,500 total vs. Wi-Fi (500+ APs at $100+ each = $50,000+) or Zigbee (200+ routers = $20,000+). Device cost: LoRa modules $2-5 vs. Wi-Fi $8-15 or NB-IoT $10-20. Connectivity cost: LoRaWAN can use private network ($0/month per device) vs. NB-IoT ($1-2/device/month = $120,000/year for 5,000 sensors). Data rate: 10 bytes/5 min = 0.0027 bps average - far below LoRa’s 0.3-50 kbps. 5-year TCO: LoRa ($2.5M) vs. NB-IoT ($3.1M) vs. Wi-Fi ($4.2M).

157.7 Technology Comparison Reference

Quick reference table for exam and design decisions:

Technology Range Power (Active) Data Rate Best Use Case
BLE 10-30m 10-20mW 1-2 Mbps Wearables, smartphones
Zigbee 10-100m 30-50mW 250 kbps Home automation, mesh
Wi-Fi 30-100m 200-400mW 1-100 Mbps High data, power available
LoRaWAN 2-15km 30-50mW 0.3-50 kbps Smart cities, agriculture
NB-IoT 10-15km 50-100mW 20-200 kbps Asset tracking, meters
Cellular 1-50km 500-2000mW 1-100 Mbps Connected vehicles, mobile

Power consumption pattern: BLE < Zigbee < LoRa < NB-IoT < Wi-Fi < Cellular

Range pattern: BLE < Zigbee/Wi-Fi < LoRa/NB-IoT < Cellular

157.8 Chapter Summary

This chapter examined the communication technologies that enable IoT connectivity:

  • Network Classifications: PAN (personal), LAN (local), MAN (metropolitan), and WAN (wide area) each serve different range and power requirements
  • Technology Selection: Match protocol capabilities to application requirements - range, power budget, data rate, and cost
  • Application Mapping: Different IoT verticals (smart home, agriculture, vehicles) align with specific communication technologies
  • UART Fundamentals: Serial communication remains essential for device interfaces, debugging, and peripheral connectivity

Understanding these communication options enables informed selection when designing IoT systems.

157.9 What’s Next?

The next chapter presents decision frameworks for technology selection and explores energy management strategies for IoT deployments.

Continue to Technology Selection and Energy ->