EEEM048: Internet of Things LSA 2022/3
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Faculty of Engineering & Physical Sciences
School of Computer Science and Electronic Engineering
Department of Electrical and Electronic Engineering
Postgraduate Programmes in Electrical and Electronic Engineering
EEEM048: Internet of Things
FHEQ Level 7 Examination
LSA 2022/3
1.
(a) Figure 1(a) Shows architecture of a pipeline monitoring system using Wireless Sensor Networks.
Figure 1(a). An architecture of a pipeline monitoring system
(i) Describe what property of a pipeline changes at a location where gas and oil leakage occur and describe what type of sensors can be used to monitor and report the leakage. [15%]
(ii) Describe the role of the Sink Nodes shown in Figure 1 and what is mean by Clusters shown in Figure 1(a). [15%]
(b) Consider an Internet of Things deployment in a farm that includes 100 sensors
deployed in an area of 3 square miles. Let’s assume that all sensor nodes have a GPRS mobile communication board, and all devices are battery powered. The sensors measure moisture and acidity levels in the soil and the sensor nodes communicate the data to an analysis application that runs on a remote server. In normal conditions each sensor collects its measurements every 10 minutes. Discuss possible solutions and strategies for reducing the power consumption and reducing the amount of data communications in this IoT deployment. [30%]
(c) Describe the Symbolic Aggregation Approximation (SAX) method and discuss how using SAX can help to summarize the monitoring data that is collected by the sensor over a long period. [20%]
(d) Geohash is a latitude/longitude Geocode method that can generate a string representation of the locations. Explain the main limitations of this method. [20%]
2.
(a) A 3 km by 3 km farm is located in a remote area that is not covered by cellular networks or broadband services through optical fibre cables. There is a house at the corner of the farm connected to a smart grid that provides it with electricity. The house has a gateway required to support ten wireless sensors evenly distributed within the farm. Each sensor is required to transmit at a data rate of at most 1 kbps. The gateway can support two communication protocols, i.e., one for the fronthaul and one for the backhaul, while the sensors can support only one protocol. Among the following protocols: IEEE 802.11ah, IEEE 802.3, ITU-T G.9903, LoRa, and NB-IoT communication protocols, what is the best protocol to be considered for each of the following links with justification?
(i) The backhaul between for gateway.
(ii) The link between the sensors and the gateway. [20 %]
(b) The IEEE 802.15.3 communication protocol is an efficient communication protocol for high-rate wireless personal area networks (WPANs).
(i) In about 200 words, describe the operation principle of the two main mechanisms
for medium access in IEEE 802.15.3 and the main differences between them with the aid of illustration figures for the superframe structure. [15 %]
(ii) You can use either choose the channel time allocation period (CTAP) or the contention access period (CAP) for the device to access the channel. Select the appropriate medium access period for the following devices to access the channel and justify your selection:
1) Surveillance cameras that need a guaranteed data rate.
2) Temperature sensors that send their measurements a few times per hour. [20 %]
(c) Satellite communication can provide solutions for some challenges that face the Internet of things.
(i) In about 200 words, discuss two potential architectures of satellites for IoT systems and suitable use cases for each architecture. [20%]
(d) Consider the link budget for FH-LoRa where a gateway is deployed over a low earth orbit (LEO) satellite. According to the link budget parameters in Table 1(d) answer the following questions:
(i) Compute the maximum slang distance between the IoT device and the satellite such that communication is possible over the satellite link. [Show the intermediate steps for the computations]
(ii) Consider a 50-degree elevation angle, what is the maximum possible altitude for the satellite such that communication is possible over the satellite link?
Table 1(d) Parameters for the link budget
|
Parameter |
Value |
|
Transmitter Gain |
2 dB |
|
Operating Frequency |
868 MHz |
|
Transmitter Power |
16 dBm |
|
Polarization Loss |
3 dB |
|
Radius of the Earth |
6371 Km |
|
Receiver Sensitivity |
-137 dBm |
|
Other Losses |
Last digit in your URN (e.g., 3 dB for URN 6862203) |
|
Received Antenna Gain |
3 dB |
[25 %]
2.
An IoT solution provider has designed a ventilation control unit for a smart home. The unit controls an air ventilation system based on the outdoor weather collecting from a rain and temperature sensors. Both sensors are battery powered and deployed in an outdoor environment. They are connected to anAC powered gateway with a network topology shown below. In the network topology, the solid line indicates a radio link. In the protocol stack, IEEE 802.15.4 is in the data link layer and RPL is used in the network layer.
(a) The temperature sensor uses a transfer function to convert a raw readout to a meaningful temperature reading. It is known that the readout values of 800 and 2500 represent 12oC and 25oC respectively. The calculation of the transfer function is given in the source code shown below:
|
float getTemp(unsigned int rawInput) { return rawInput*(V1+V2)+(V1-V2); } |
Determine V1 and V2. What is the lowest temperature can be supported by this temperature sensor? [20 %]
(b) Apart from controlling the air ventilation system, the sensed data are also stored for a month in a cloud server for users to view the historical data. Currently, the service provider offers a dedicated wireless monitoring device with a 5-inch touch screen display for users to conveniently access the data. The monitoring device is connected to the Internet, and it periodically pulls data from the cloud server using preconfigured account information. In an internal discussion, the engineer proposing the design claims that the system is secure since a private key and other account information are hardcoded in an SD memory card attached inside the device for authentication and data encryption. However, other engineers have some concern with the data privacy. Identify two vulnerabilities and argue that they can compromise the data privacy. [20 %]
(c) The IEEE 802.15.4 technology supports beacon and non-beacon modes. Which mode do you recommend using and why?
For RPL setting, the engineer accidentally configures the rain sensor to be the root. Discuss whether this configuration causes any operation or performance issues. To adequately configure RPL, which node should be used as the root? [30 %]
(d) In the system, the engineer programs the temperature sensor node to report its temperature reading every 5 minutes. For the rain sensor node, whenever a temperature reading is received, it immediately relays the received information to the gateway, followed by reading the rain detection outcome and transmitting the outcome to the gateway. Both sensor nodes are based on the same node architecture. After some measurement over an hour period, it is found that the rain sensor node draws 320μA on average and the temperature sensor draws 20μA lesser than that of the rain sensor node.
To ensure that both sensor nodes can operate for at least 300 days, what battery capacity (in mAh) should you use for each sensor node? Another engineer has pointed out that the energy consumption of the rain sensor can be reduced by reworking the software logic. How do you think this can be achieved? [30 %]
2024-01-15