Wireless Networking aka “Wireless for IoT Class”

Course code: CS4222/CS5422

Semester 2, 2022/2023

Instructor: Professor Ambuj Varshney

Contact: ambujv@nus.edu.sg, COM3: #02-25

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TUTORIAL 9 (Optional) for WEEK 13 (Starting 3rd April 2023)

This is a non-graded tutorial. In this tutorial session, we provide some sample questions to help you prepare for final examination.

[1] Question 1: You are developing an application to deploy IoT devices in urban areas to help monitor air quality. These IoT devices measure air pollution levels and transmit the information to a base station located in the city. The base stations are located several kilometers away from the IoT devices. In this deployment, you plan to use LoRa for communication. You can assume that there is no synchronization among various devices and base station.

• What are the available frequency bands for IoT device? (1 point)
• Assuming each sensor requires 125 KHz of bandwidth for communication and that there is a total of 20 MHz bandwidth available for uplink communication, calculate the number of devices that can concurrently transmit to the base station when employing FSK and when employing LoRa with CSS. Please justify your answer and mention any assumptions made while performing this calculation. (2 points)
• What are the advantages of using the LoRa protocol over other long-range standards such as FSK/SigFox? (1 point)
• Which medium access control mechanism would you prefer for this deployment, and what is the rationale behind your choice? (1 point)
• Given that we use the highest sensitivity mode of the LoRa receiver at the base station (-146 dBm), and both the air quality sensor and base station are equipped with antennas with a gain of 2 dB, and the distance between them is 4 kilometers, what is the minimum transmitter strength required to ensure successful reception at the base station? (4 points)

[2] Question 2: The IPv6 protocol facilitates the extensive deployment of IoT devices on a vast scale. When implementing IoT devices that utilize the IPv6 protocol at the network layer, consider the following questions:

• What benefits does IPv6 offer over IPv4 in the context of the Internet of Things? How many addresses does IPv4 support? (2 points)

• What header and address compression mechanisms are employed within the IPv6 protocol? (2 points)

• Expand the following IPv6 address into its full form: aecb:222::10 (2 points)

[3] Question 3: Bluetooth is among the most prevalent protocols utilized in the Internet of Things (IoT). When deploying an IoT network that employs the Bluetooth standard, consider the following questions:

• When using Bluetooth 4.2, with a PHY data rate of 1 Megabit/second, how many milliseconds does it take to transmit a single Bluetooth advertisement packet? How does this compare to using the BLE 5.2 standard? (1 point)

• Given a Bluetooth transmitter that consumes 10 milliwatts, what is the energy expenditure for transmitting a single advertisement cycle? (2 points)

• Would you prefer to stream audio data using a connection-oriented or advertising mode? Instead, if you want to send beacons? Explain your reasoning. (1 point)

• The most recent version of the Bluetooth standard supports extended advertisements. Which Bluetooth channels are employed to facilitate this communication? (2 points)