An IoT Architecture for Ubiquitous Context-Aware Assessments

Abstract

Ubiquitous learning environments aim to move students out of classrooms and into the real world where learners can engage in experiential and tangible learning. Ubiquitous assessment systems are one class of learning environments that enact student learning in the form of teacher, peer, and system-generated assessments that incorporate physical aspects of objects in outdoor locations. A key component of such systems is a wireless-enabled edge device augmented with various types of sensors to represent the state of physical objects and environments. Most such current systems are constructed using traditional Internet technologies which are not suited for this purpose and hence leading to cumbersome and complex designs. This thesis presents a novel generic technical architecture for such systems built around Internet of Things (IoT) computing platforms. The newly proposed architecture is designed to seamlessly incorporate various IoT communication protocols. A commonly used IoT edge device was used to implement four variants of the proposed architecture. The variants based on Advanced Message Queuing Protocol (AMQP), Constrained Application Protocol (CoAP), Message Queue Telemetry Transport (MQTT), and Extensible Messaging and Presence Protocol (XMPP) IoT protocols were evaluated using an experimental setup. Each implementation was evaluated in terms of power consumption, CPU utilization and RAM usage, as well as end-to-end latency and throughput in response to network disturbances. In addition, qualitative aspects of each implementation were analysed based on maximum message size, overhead, security, reliability, and ease of implementation and flexibility. While there were statistical differences in power consumption between the four implementations, the practical difference was negligible. CoAP proved to be the most efficient in terms of CPU and memory utilization but produced the lowest latency in lagged networks only. However, due to payload limitations and lack of reliability features, CoAP was considered ill-suited for such applications. Among the other three variants, MQTT and AMQP seem more appropriate in terms of qualitative features, although MQTT was more resource efficient in most technical aspects.