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Faculty of Engineering & Physical Sciences

Department of Electrical and Electronic Engineering

Undergraduate Programmes in Electrical and Electronic Engineering

EEEM048:   Internet of Things

FHEQ Level 7 Examination

Semester 1  2020/1

1.

(a)        Compare the thread-based and event-based programming methods in an IoT system. Give a programming example in a ContikiOS for each of them. [20 %]

(b)        Compare the HTTP protocol versus CoAP protocol in a web system. [20 %]

(c)        Consider the wireless network shown in Figure 1.

Figure 1. A Wireless Sensor Network with a gateway node

Explain the role of the gateway node, and; Explain what type of devices and which type of communication links can be used as a gateway in this network? [20 %]

(d)        Consider we have an Internet of Things solution for monitoring patients with cardiac conditions in their home. You will work with 5 companies that will each supply a set of devices. The sets are similar to each other, but they use different brands and design. Each patient will have a choice of using whichever set of devices he/she finds the easiest and most convenient. These devices will include wearable sensors for monitoring heart rate, walking steps, and connected devices for measuring oxygen levels in blood, blood pressure and body temperature monitoring. The proposed solution will have a unified and integrated secure application that will allow clinicians to view the patient data remotely. Discuss the data interoperability issues and suggest a solution to overcome the data interoperability problem in the project. [20 %]

(e)        Consider the following ContikiOS process code shown in Figure 2.

Figure 2. A process in ContikiOS

Where d1 is integer function, and d2 is float function used for printing floating-point numbers. What does the process calculate and print? [20 %]

2.

(a)        Consider the following Timeseries Data:

(x): 2, 5, 7, 10, 5, 10, 2, 2, 5, 7, 10, 10

(i)         Calculate the normalised representation of this time series data using standardised z- score. [10 %]

(ii)        Calculate the Piecewise Aggregate Approximation (PAA) representation of the normalized times series while considering the window size of 2 measurements per window. [10 %]

(iii)       Write the SAX word representing this time series data. Assume that the SAX uses 5 symbol alphabets and the number of breakpoints is 4, and the range is calculated based on Table 1.

[10%]

(b)        Consider the following measurement of a sensor:

25          F         11:20       AM      86.454114     -0.2401923

Draw an RDF graph and an XML script for the above measurement. [20 %]

(c)        An IoT system is installed in a home environment for smart lighting, temperature control, ventilation, outdoor surveillance and  security. The IoT devices and the gateway can be configured to use either WiFi module or IEEE 802.15.4 communication module, and currently all IoT devices are set to use WiFi to communicate with the gateway. It is found that the IoT devices require frequent replacement of batteries due to the high energy consumption from the WiFi communication module. To address this issue, an engineer suggests reconfiguring all devices and the gateway to use IEEE 802.15.4 communication module instead. Predict potential problems that may arise with this reconfiguration and how the problems affect the system performance. Justify your answer. [20 %]

(c)           A number of sensor nodes and a gateway are deployed in a meeting room. A star network is formed to connect the sensor nodes to the gateway. All the sensor nodes are powered by batteries, and they perform periodic sensing and sensor data reporting to a server 20 times every hour. It is found that the sensor nodes can operate for 250 days before a battery replacement is needed, and the batteries of all sensors are replaced at the sametime.

To reduce the frequency of the battery replacement, two actions have been taken simultaneously, including using a new type of batteries which have 50% more capacity and reducing the frequency of periodic tasks of each sensor node by 40% to 12 times per hour. With the two actions, the sensor nodes can operate for 400 days. If the frequency of periodic tasks of each sensor node is further reduced by another 50% to 6 times per hour, determine how long the sensors can operate after the new type of batteries are installed in all sensor nodes. [20 %]

(d)           The IEEE 802.15.4 MAC protocol has a specific feature to extend the battery life of a sensor node.

(i)         Identify the feature and explain how it can reduce the battery consumption of a sensor node. [10 %]

(ii)        The feature may affect network performance in terms of bandwidth. Considering a star network consisting of a large number of sensor nodes, evaluate the performance impact of the feature for the considered network and discuss whether the feature will improve or degrade the network performance. [20 %]