Connectivity and Network Technologies

Introduction

The Internet of Things (IoT) depends on communication technologies that connect sensors, actuators, gateways, cloud platforms, and users. Connectivity is not a single engineering choice. A technology that is excellent for a factory robot may be unsuitable for a soil-moisture sensor, while a low-power wide-area network may be inappropriate for a high-definition camera. IoT network design therefore requires matching application requirements with range, throughput, latency, energy consumption, topology, reliability, security, deployment complexity, and cost.

This chapter compares major wired and wireless technologies used in IoT: Ethernet, Wi-Fi, Bluetooth Low Energy (BLE), Zigbee, Thread, RFID, NFC, low-power wide-area networks (LPWANs), LoRaWAN, NB-IoT, LTE-M, and 5G. The comparison is architectural rather than merely numerical. Published data rates and ranges vary with spectrum, channel width, modulation, antenna design, regulatory limits, interference, building materials, traffic load, and implementation quality.

Learning Objectives

After studying this chapter, a student should be able to:

1. Explain the role of connectivity in an IoT architecture.
2. Compare wired and wireless technologies using range, throughput, latency, power, topology, reliability, and cost.
3. Distinguish personal-area, local-area, field-area, and wide-area IoT networks.
4. Select an appropriate connectivity technology for a specified application.
5. Explain the operation and trade-offs of Ethernet, Wi-Fi, BLE, Zigbee, Thread, RFID, NFC, LoRaWAN, NB-IoT, LTE-M, and 5G.
6. Identify security, regulatory, interoperability, and lifecycle concerns in IoT deployments.

1. Connectivity as an IoT Design Decision

An IoT system commonly contains four communication layers:

• Device or node layer: sensors, actuators, tags, meters, and embedded controllers.
• Access or field network: the local wireless or wired link connecting devices to a gateway or access point.
• Backhaul network: the connection from a gateway or base station to an enterprise network or cloud service.
• Application layer: data processing, control, visualization, and integration with business systems.

The most suitable technology depends on the required communication pattern. A sensor may transmit a few bytes every hour, whereas a camera may transmit many megabits per second continuously. Some applications require millisecond-level control; others tolerate delays of several minutes. Battery-powered devices may need to operate for years, while mains-powered equipment can use more energy for higher performance.

Important design variables include:

• Range: distance over which communication is dependable, not merely detectable.
• Throughput: useful application data delivered per unit time, normally measured in bit/s.
• Latency: time between sending information and receiving or acting on it.
• Energy consumption: energy used for transmission, reception, processing, and sleep/wake transitions.
• Topology: arrangement of nodes, such as point-to-point, star, mesh, tree, or cellular.
• Reliability: probability that data reaches its destination correctly and within a required time.
• Cost: device hardware, installation, spectrum, subscription, maintenance, and lifecycle costs.
• Security: protection of confidentiality, integrity, availability, identity, and privacy.

A nominal physical-layer rate is not equivalent to application throughput. Protocol headers, acknowledgements, retransmissions, contention, encryption, sleep schedules, and poor radio conditions reduce useful performance.

2. A Taxonomy of IoT Connectivity

IoT networks can be classified by geographic scale:

Another useful classification is by energy and data demand. High-data devices such as cameras and industrial controllers usually require Ethernet, Wi-Fi, or 5G. Low-data battery devices commonly use BLE, Zigbee, Thread, LoRaWAN, NB-IoT, or LTE-M. RFID and NFC are distinctive because communication may be initiated through proximity and, in some configurations, the tag receives operating power from the reader field.

3. Wired Connectivity

3.1 Ethernet

Ethernet is a family of IEEE 802.3 technologies used in homes, offices, data centers, industrial systems, and IoT gateways. Modern Ethernet commonly uses switched full-duplex links over twisted-pair copper or fiber. Common rates include 100 Mb/s, 1 Gb/s, 2.5 Gb/s, 10 Gb/s, and higher, although the rate selected depends on equipment and cable category.

Ethernet provides high throughput, predictable local performance, low latency, and strong physical security compared with radio links. Power over Ethernet (PoE) can carry both data and electrical power over suitable twisted-pair cabling. This simplifies installation for cameras, access points, intercoms, and industrial endpoints. IEEE PoE variants differ in available power and negotiation behavior; designers must verify the power class, cable, switch budget, and device requirement.

Its limitations are cabling cost, restricted mobility, installation difficulty, and vulnerability to cable damage. Ethernet is usually a strong choice for fixed gateways, industrial controllers, cameras, and infrastructure requiring dependable high bandwidth.

3.2 Industrial Ethernet

Industrial Ethernet applies Ethernet to demanding environments using rugged connectors, redundancy, time synchronization, traffic prioritization, and specialized protocols. Examples include PROFINET, EtherNet/IP, EtherCAT, and TSN-based systems. Time-Sensitive Networking (TSN) extends Ethernet with mechanisms for bounded latency and synchronized traffic, making it relevant to industrial control. It should not be assumed that ordinary office Ethernet automatically provides deterministic control behavior.

4. Wireless Local and Personal Networks

4.1 Wi-Fi

Wi-Fi is based on IEEE 802.11 and is normally deployed through an access point in a star-like infrastructure topology. It provides substantially higher throughput than most low-power IoT protocols and can support cameras, appliances, displays, software updates, and gateways. Wi-Fi operates in several unlicensed bands, including 2.4 GHz and, depending on region and generation, 5 GHz and 6 GHz.

Wi-Fi advantages include widespread availability, mature IP support, high throughput, and easy integration with existing networks. Wi-Fi 6 and later generations improve efficiency in dense environments through features such as orthogonal frequency-division multiple access and improved scheduling. However, actual performance depends on channel utilization, interference, distance, walls, access-point placement, and client behavior.

Wi-Fi radios generally consume more energy than BLE, Zigbee, or Thread radios, although power-saving modes can reduce consumption. Wi-Fi is therefore appropriate for mains-powered devices, devices with rechargeable batteries and substantial data requirements, and gateways. It is less suitable for tiny sensors expected to operate for years on a small battery.

4.2 Bluetooth Low Energy

Bluetooth Low Energy is designed for short-range, low-power communication. A common model is a star in which a central device communicates with peripheral devices. BLE supports advertising and scanning for discovery and connection-oriented communication for structured data exchange. It is widely used in wearables, beacons, medical accessories, asset tags, and device commissioning.

BLE offers low hardware cost, broad smartphone support, and energy-efficient intermittent communication. Its practical range can extend from a few metres to tens or, under favorable conditions, more than one hundred metres using suitable PHY options and antennas. Higher range usually involves lower data rates, greater airtime, or both. BLE 5 introduced features such as longer-range coded PHY modes and larger advertising capacity, but these do not make every BLE device a long-range, high-throughput system.

BLE mesh enables many-to-many communication for selected lighting and building applications. Mesh introduces relay traffic, provisioning complexity, and additional energy considerations. BLE is generally not a replacement for cellular or LPWAN connectivity over kilometres.

4.3 Zigbee

Zigbee is a low-power wireless technology commonly associated with IEEE 802.15.4 physical and link layers and higher-layer specifications developed through industry alliances. Zigbee networks commonly use a coordinator, routers, and end devices. Routers can relay traffic, allowing mesh coverage beyond a single radio hop.

Zigbee is suitable for lighting, building automation, environmental sensing, and home devices. Its strengths include low energy consumption, mesh networking, modest hardware cost, and support for many nodes. Its weaknesses include limited throughput, dependence on correct channel planning, and interoperability issues when products implement different application profiles or certification levels. Battery-powered end devices can sleep, while mains-powered routers normally remain available to maintain the mesh.

4.4 Thread

Thread is an IPv6-based low-power mesh networking technology built on IEEE 802.15.4 radios. It uses secure mesh routing and is designed for home and building applications. Thread border routers connect the Thread mesh to other IP networks; they do not necessarily perform application translation, because Thread devices can use IPv6 addressing.

Thread's principal advantages are IP-native operation, self-healing mesh behavior, low power, and multi-vendor ecosystem potential. A Thread network normally contains routers, sleepy end devices, and one or more border routers. Thread itself is a network technology, not a complete application model; application interoperability may be supplied by systems such as Matter or other protocols.

4.5 Comparative Local-Wireless View

The ranges in this table are engineering categories, not guaranteed specifications. Walls, metal structures, interference, antenna placement, and local regulations can change them substantially.

5. Proximity and Identification Technologies

5.1 RFID

Radio-frequency identification uses a reader and an electronic tag. Tags may be passive, semi-passive, or active. Passive tags obtain energy from the reader's electromagnetic field and respond by modulating or backscattering the field. Active tags contain a battery and can provide longer range or additional sensing capability.

RFID is particularly useful when identity must be read without line-of-sight, such as inventory, access control, library systems, animal identification, and supply-chain tracking. RFID performance depends strongly on frequency band, tag orientation, reader power, surrounding materials, and regulatory limits. RFID is primarily an identification and short-message technology rather than a general-purpose IP network.

Security varies widely. A simple tag identifier may be copied, while advanced tags can support cryptographic authentication. Systems handling valuable goods or personal information should not treat possession of a tag identifier as proof of identity.

5.2 NFC

Near Field Communication operates at very short range, typically requiring close placement of devices. NFC supports reader/writer, card-emulation, and peer-related modes, although practical product behavior depends on the device and application. It is used for contactless payment, access credentials, product interaction, pairing, and device commissioning.

NFC's short range is a usability advantage and a security aid, but it is not a guarantee of security. Relay attacks, malicious tags, weak application authentication, and insecure backend systems remain possible. NFC is also useful for transferring configuration credentials to a device that subsequently communicates through Wi-Fi, BLE, or another network.

6. Low-Power Wide-Area Networking

LPWAN technologies are designed for small payloads, low energy consumption, and wide geographic coverage. They generally sacrifice throughput and sometimes latency in exchange for battery life and range. LPWAN applications include utility metering, environmental monitoring, parking, agriculture, logistics, and infrastructure sensing.

A key engineering principle is that long range does not automatically mean low cost or low energy in every situation. Transmitting at high power, repeating messages, maintaining cellular registration, or using frequent downlink communication can substantially increase energy consumption. Device placement, antenna quality, payload size, reporting interval, and network coverage are central design factors.

6.1 LoRaWAN

LoRaWAN is a low-power wide-area networking architecture commonly using LoRa modulation in unlicensed spectrum. End devices communicate with gateways, and gateways forward packets to a network server over an IP backhaul. The architecture is often described as a star-of-stars topology: end devices do not normally relay one another's traffic.

LoRaWAN supports long range and low-power operation for small, infrequent uplinks. Adaptive Data Rate can adjust data rate and transmission parameters when link conditions and application behavior permit. LoRaWAN classes provide different downlink availability and power characteristics: Class A prioritizes energy efficiency, while Classes B and C offer more opportunities for downlink at increased energy cost.

LoRaWAN is not intended for continuous high-rate data or strict real-time control. Duty-cycle regulations, airtime limitations, collisions, gateway capacity, payload constraints, and downlink scarcity must be considered. Network ownership may be public, private, or community-based, and the economic model depends on deployment scale and service availability.

6.2 NB-IoT

Narrowband Internet of Things is a 3GPP cellular technology optimized for low-data-rate IoT. It benefits from licensed spectrum, operator-managed infrastructure, strong coverage engineering, and support for devices that can remain mostly idle. NB-IoT can provide deep coverage in challenging locations and supports very long battery life for suitable reporting patterns.

NB-IoT is appropriate for smart meters, fixed sensors, and other applications with small messages and limited mobility requirements. Latency can be variable, especially when devices use power-saving modes or extended discontinuous reception. A subscription, operator dependence, SIM or eSIM management, and cellular module cost are part of the total cost.

6.3 LTE-M

LTE-M, also called LTE Cat-M1, is another 3GPP cellular IoT technology. Compared with NB-IoT, LTE-M generally supports higher throughput, lower latency, mobility, and voice-related capabilities in relevant deployments. It is suitable for asset tracking, wearables, alarms, and mobile sensors where a compromise between energy efficiency and performance is required.

LTE-M normally costs more energy and may require a more capable module than the simplest NB-IoT device, but its support for mobility and firmware updates can reduce system complexity. Availability depends on mobile-network operators and regional deployment strategies.

6.4 5G

5G is a broad cellular system rather than one single IoT profile. It can support enhanced mobile broadband, massive machine-type communication, and ultra-reliable low-latency communication through different capabilities and deployment configurations. Features such as network slicing, edge computing, private networks, and improved radio performance can support industrial and enterprise IoT.

5G is well suited to mobile robots, machine vision backhaul, connected vehicles, industrial automation, and high-density devices when the required service and infrastructure are available. It is usually more expensive and power-intensive than low-power sensor technologies. Claims of ultra-low latency must be interpreted carefully: radio latency is only one part of end-to-end latency, which also includes device processing, transport, queues, application processing, and actuator response.

7. Comparative Decision Framework

The following qualitative matrix supports initial selection.

A disciplined selection process asks:

1. Is the device fixed or mobile?
2. What payload size and reporting frequency are required?
3. What is the maximum acceptable latency and jitter?
4. Must the device run for years on a battery?
5. Is downlink frequent, rare, or unnecessary?
6. Is infrastructure already available?
7. Is licensed or unlicensed spectrum preferable?
8. What are the installation, subscription, and maintenance costs?
9. What security and regulatory controls apply?
10. Can the technology support firmware updates and device replacement over the expected lifecycle?

A Simple Energy Estimate

For a battery-powered node, an early estimate of battery life can be obtained from average current:

Here, I_avg is average current in amperes; I_tx, I_rx, I_sleep, and I_other are operating currents; the corresponding t values are durations; and T is the complete observation period. The equation assumes that current is approximately constant within each operating state and ignores battery aging, temperature, regulator losses, and self-discharge.

An approximate idealized operating time is:

where C is usable battery capacity in ampere-hours and t_life is in hours. This is only an estimate: the usable capacity depends on discharge rate and temperature, and a device may stop operating before the nominal capacity is fully delivered.

Worked Example

Suppose a sensor, during a 60-minute cycle, transmits for 2 seconds at 40 mA, receives for 3 seconds at 15 mA, and sleeps for the remaining 3,595 seconds at 0.02 mA. Ignoring other loads:

The numerator is 80 + 45 + 71.9 = 196.9 mA·s. Therefore:

With a nominal 2,000 mAh battery, the ideal estimate is:

A practical design would derate this result for battery chemistry, temperature, radio retries, leakage, regulator efficiency, and required reserve. The example illustrates why sleep current and reporting frequency can matter more than brief transmit current.

8. Applied Case: Smart Irrigation Across a University Farm

The following is an illustrative case.

Background

A university operates a 120-hectare experimental farm. Soil-moisture, temperature, and salinity sensors are distributed across fields. The system must report measurements every 15 minutes, operate for several years on batteries, and control irrigation valves. Some fields are several kilometres from the campus network. A small number of cameras are also required for security.

Problem

The farm needs wide coverage, low energy consumption, occasional downlink commands, and reliable operation despite vegetation, weather, and limited power infrastructure. Continuous high throughput is not required for sensors, but cameras require considerably more bandwidth.

Analysis

Wi-Fi would require many access points and would impose higher energy demand on remote sensors. Ethernet would be reliable but expensive to install over large distances. BLE, Zigbee, and Thread could serve local clusters but would require gateways or mesh infrastructure, and agricultural distances may exceed practical multi-hop density. A cellular solution could provide wide coverage but would create recurring subscription costs and potentially higher module energy consumption.

LoRaWAN is suitable for sparse, small sensor messages and can be deployed with a few strategically placed gateways. Valve control must be designed conservatively because downlink availability and latency are not equivalent to a wired control loop. Safety-critical irrigation interlocks should remain local to the valve controller rather than depend exclusively on a cloud path. LTE-M may be preferable for mobile equipment or devices requiring more frequent downlink and firmware updates. Cameras should use wired Ethernet where feasible or Wi-Fi/5G where mobility and installation conditions justify it.

Approach and Solution

The proposed architecture uses LoRaWAN for soil sensors, local control logic at irrigation cabinets, Ethernet or fiber for fixed cameras near buildings, and Wi-Fi or cellular connectivity for remote video sites. Each sensor uses authenticated and encrypted communication, reports link quality and battery status, and supports staged firmware maintenance. Gateways have redundant backhaul where irrigation operations are important.

Outcome

The design reduces field cabling and sensor energy consumption while separating low-rate sensing from high-rate video. Local valve logic maintains safe operation during cloud or backhaul outages. The total cost includes gateways, poles, batteries, installation, subscriptions where applicable, cybersecurity maintenance, and eventual replacement—not only the radio modules.

Learning Points

1. One farm may require several connectivity technologies.
2. The best network for sensing may not be the best network for actuation or video.
3. Local fallback control is essential when network availability is uncertain.
4. Battery-life claims must use realistic traffic and environmental assumptions.
5. Total cost of ownership and lifecycle security are as important as initial range.

9. Security, Governance, and Operational Issues

Connectivity selection creates security responsibilities. Important controls include unique device identity, mutual authentication, encryption in transit, secure key storage, signed firmware, secure boot where appropriate, access control, logging, vulnerability management, and a documented end-of-life process. Default passwords and shared credentials are unacceptable for professional deployments.

The security model differs by technology. Wi-Fi networks require secure enterprise or personal authentication and correctly configured segmentation. BLE devices require careful pairing, bonding, and application-layer authorization. Zigbee and Thread deployments require secure commissioning and key management. LoRaWAN uses security keys and network/application separation, but poor key storage or insecure provisioning can compromise the system. Cellular technologies inherit substantial protection from operator infrastructure, but the endpoint, SIM or eSIM, application, and cloud service still require security controls.

Privacy is relevant when connectivity enables location tracking, access records, health information, or behavioral inference. Organizations should minimize data collection, define retention periods, obtain appropriate consent, and restrict secondary uses. Regulatory obligations may include radio-spectrum rules, data-protection law, electrical safety, sector-specific rules, and cybersecurity requirements for critical infrastructure.

Interoperability should be evaluated at three levels: radio compatibility, network-layer compatibility, and application semantics. Two products may use the same radio but still fail to exchange meaningful data. Open standards and certified profiles can reduce vendor lock-in, but certification does not eliminate integration testing.

10. Contemporary Developments and Best Practices

Current IoT deployments increasingly combine technologies rather than selecting one universal network. Matter uses IP-based ecosystems in selected consumer and building contexts, often relying on Wi-Fi, Thread, and Ethernet, with Bluetooth used for commissioning. Private 5G and edge computing are developing in industrial environments. Satellite IoT can extend coverage to remote areas, although antenna, energy, latency, and service costs require careful evaluation.

Best practices include:

• Measure the real radio environment before final deployment.
• Design for maximum, not average, traffic and node density.
• Separate safety-critical control from noncritical cloud analytics.
• Budget energy for retries, firmware updates, and worst-case conditions.
• Select antennas and enclosures as part of the communication system.
• Test coexistence among Wi-Fi, Bluetooth, Zigbee, Thread, and other radios.
• Use gateways and protocol translation only when their operational burden is understood.
• Provide observability: battery level, signal quality, packet loss, latency, and firmware status.
• Plan credential rotation, replacement, and secure decommissioning.
• Compare total cost of ownership over the complete service life.

Artificial intelligence can help forecast battery failure, detect anomalous traffic, optimize radio parameters, and predict equipment faults. However, AI does not remove the need for reliable measurements, secure data, explainable operational decisions, and human oversight. An AI system operating a physical process must have bounded actions and safe fallback behavior.

Challenges and Limitations

No connectivity technology simultaneously maximizes range, throughput, low power, low latency, low cost, and universal coverage. Fundamental trade-offs arise from propagation physics, spectrum availability, hardware complexity, network capacity, and energy limits. Wireless links are affected by interference and changing environments. Licensed cellular services provide managed coverage but introduce operator dependence and recurring fees. Unlicensed systems can reduce subscription costs but may face congestion and regulatory restrictions.

Technology lifecycles also create risk. A network may be technically successful yet become uneconomical when a cellular generation is retired, a vendor stops supporting firmware, or replacement modules become unavailable. Procurement should therefore examine standards maturity, regional availability, certification, update policy, and exit options.

Chapter Summary

IoT connectivity must be selected by matching application requirements to technical and economic characteristics. Ethernet provides dependable, high-throughput wired communication and can deliver power through PoE. Wi-Fi offers high local throughput but generally consumes more energy than low-power alternatives. BLE supports short-range, low-energy personal-area applications, while Zigbee and Thread provide low-power mesh networking; Thread additionally offers an IP-native architecture. RFID and NFC specialize in identification, proximity interaction, and commissioning rather than general networking.

LoRaWAN supports long-range, low-rate communication through a star-of-stars architecture and is well suited to sparse battery-powered sensing. NB-IoT and LTE-M use cellular infrastructure, with NB-IoT emphasizing low-rate fixed devices and coverage, and LTE-M offering stronger mobility and higher performance for many applications. 5G supports demanding mobile, industrial, and high-density use cases but generally has higher infrastructure and energy costs.

Range, throughput, latency, power, topology, reliability, security, regulatory constraints, and total cost must be evaluated together. Successful IoT systems frequently use multiple technologies and retain local control for safety and resilience. A professional engineer validates assumptions through field tests, realistic energy calculations, lifecycle planning, and security analysis.

Key Terms

Ethernet: A family of wired networking technologies standardized primarily by IEEE 802.3.

Wi-Fi: Wireless local-area networking based primarily on IEEE 802.11.

Bluetooth Low Energy: A short-range wireless technology optimized for low-power data exchange.

Zigbee: A low-power wireless ecosystem commonly built on IEEE 802.15.4.

Thread: An IPv6-based low-power mesh networking technology.

RFID: Radio-frequency identification using readers and electronic tags.

NFC: Near Field Communication for very short-range wireless interaction.

LPWAN: Low-power wide-area network designed for long-range, low-rate communication.

LoRaWAN: A wide-area networking architecture commonly using LoRa modulation.

NB-IoT: A 3GPP cellular technology for low-rate IoT communication.

LTE-M: A cellular IoT technology supporting greater mobility and throughput than many NB-IoT applications.

5G: A cellular system supporting enhanced broadband, massive machine communication, and advanced low-latency services.

Throughput: Useful application data delivered per unit time.

Latency: Time delay between an event, transmission, and its response.

Topology: Structural arrangement of nodes and communication links.

Mesh network: A network in which nodes can forward traffic for other nodes.

Gateway: A device that connects one network or protocol to another.

Backhaul: The network path connecting an access network or gateway to a core or cloud service.

Total cost of ownership: The complete lifecycle cost, including hardware, installation, operation, maintenance, subscriptions, and replacement.

Review Questions

Short Answer Questions

1. Why is nominal radio data rate different from application throughput?
2. State two advantages and two limitations of Ethernet for IoT.
3. What distinguishes Thread from many non-IP low-power mesh systems?
4. Why are RFID and NFC not normally treated as general-purpose wide-area networks?
5. Name three factors that affect practical battery life in an IoT device.

Long Answer Questions

1. Compare Wi-Fi, BLE, Zigbee, and Thread for a smart-building deployment.
2. Explain the architecture, strengths, and limitations of LoRaWAN.
3. Compare NB-IoT, LTE-M, and 5G for asset tracking applications.
4. Discuss how topology influences reliability, energy consumption, and maintenance.
5. Explain the security and privacy responsibilities associated with IoT connectivity.

Analytical / Application Questions

1. Select technologies for a university campus containing battery-powered room sensors, security cameras, mobile robots, and access-control readers. Justify each selection using range, throughput, latency, power, topology, and cost.
2. A remote environmental sensor transmits once every 30 minutes but must operate for five years. Design a connectivity and energy strategy, identify assumptions, and explain how you would validate the battery-life estimate.
3. A factory requires closed-loop motion control, environmental sensing, and worker asset tracking. Propose a multi-network architecture and explain why a single connectivity technology would be inappropriate.

Multiple Choice Questions with Answers

Question 1

Which technology is generally most appropriate for a fixed IoT camera requiring high local throughput?

A. NFC

B. Ethernet

C. RFID

D. LoRaWAN

Correct Answer: B. Ethernet

Question 2

What is a defining characteristic of Thread?

A. It is an IPv6-based low-power mesh technology

B. It requires a wired connection for every sensor

C. It is designed primarily for passive identification tags

D. It provides cellular wide-area coverage by itself

Correct Answer: A. It is an IPv6-based low-power mesh technology

Question 3

Which technology normally uses a star-of-stars architecture with end devices communicating through gateways?

A. LoRaWAN

B. Ethernet

C. NFC

D. Industrial Ethernet TSN

Correct Answer: A. LoRaWAN

Question 4

Compared with NB-IoT, LTE-M generally provides better support for which capability?

A. Passive tag operation without a battery

B. Mobility and higher device throughput

C. Reader-to-tag near-field coupling

D. Unlicensed-only operation

Correct Answer: B. Mobility and higher device throughput

Question 5

A sensor operates at 40 mA for 2 s, 15 mA for 3 s, and 0.02 mA for the remaining 3595 s of a 3600 s cycle. What is its approximate average current?

A. 0.005 mA

B. 0.055 mA

C. 0.55 mA

D. 5.5 mA

Correct Answer: B. 0.055 mA

Question 6

Which technology is specifically designed for very short-range contactless interaction such as payment or tap-to-pair?

A. NFC

B. 5G

C. NB-IoT

D. Ethernet

Correct Answer: A. NFC

Question 7

Why is Wi-Fi often less suitable than BLE for a tiny sensor expected to run for years on a small battery?

A. Wi-Fi cannot transmit digital data

B. Wi-Fi generally has higher energy demand

C. BLE cannot operate indoors

D. Wi-Fi has no security mechanisms

Correct Answer: B. Wi-Fi generally has higher energy demand

Question 8

Which factor most directly reduces useful application throughput below a nominal physical-layer rate?

A. Protocol overhead and retransmissions

B. Using unique device identities

C. Installing a secure boot process

D. Using a shorter device name

Correct Answer: A. Protocol overhead and retransmissions

Question 9

In the illustrative farm case, why should safety-critical valve logic not depend exclusively on a cloud path?

A. Cloud services always prohibit sensors

B. Backhaul outages and variable latency can interrupt control

C. LoRaWAN cannot send any uplink messages

D. Ethernet cannot control actuators

Correct Answer: B. Backhaul outages and variable latency can interrupt control

Question 10

Which item is part of total cost of ownership for an IoT connectivity solution?

A. Only the initial radio-chip price

B. Installation, subscriptions, maintenance, and replacement

C. Only the nominal data rate

D. Only the antenna color

Correct Answer: B. Installation, subscriptions, maintenance, and replacement