Design of on-line quizzes to replace formal exam in an information and communications technology unit

The onset of COVID-19 pandemic in early 2020 saw a renewed interest in designing alternative, on-line assessments to replace the formal exams, which coincidentally aligned with the assessment design requirement of CQU Renew Unit Refresh. However, designing such assessments is challenging for several reasons, including the potential compromise of the academic integrity [1]. The academic integrity may be challenged because of the infeasibility in most cases to invigilate the assessment. This presentation will share the challenges and opportunities of designing an on-line assessment to replace the formal exam, and the success story of the same from a Computer Forensics unit at CQUniversity at the undergraduate level. The unit used carefully designed Moodle quizzes for this purpose. The highly technical nature of the unit demanded that the new assessment be engaging at the technology and techniques levels for adequate assessment of student learning. The overarching goal was to design the quizzes in a way to mimic the critical thinking required in the unit's past formal exams, reducing the opportunities for cheating, and creating a differentiation between the passing grade and D/HD grades. To achieve this, scenario-based questions on digital forensic investigations were crafted for a mix of MCQ and free text input answers, in addition to a handful of weekly quiz type MCQ questions. Additionally, to allow students' familiarity with the quiz environment, a mock test was provided under the same conditions as of the actual on-line assessment, with time-limitation and randomised questions to further reduce the opportunities for cheating [2]. While no formal study was conducted on the academic integrity matter, observations by the Unit Coordinator, quiz results, and informal feedback from students pointed to the success of the quiz assessment both in terms of its capability of assessing student learning and deterring academic integrity issues

Cell-hopping: A new architecture for wireless communications

Recent advances in IEEE 802.11 (Wi-Fi) standards have led to unprecedented opportunities for commercial success and low pricing in wireless networking. Wireless access points that are easy to setup, use, and maintain, have become a household commodity. Inspired by the added benefit of their operation in the unlicensed frequency band, many home and small business owners are installing these commodity access points to quickly set up a high speed local wireless network within their premises. As this trend continues to grow, we will soon end up with a wide coverage of independent commodity access points in residential or commercial areas serving individual premises. Although these access points serve their intended purpose of networking indoor devices, they themselves do not provide any wide area communication services to mobile users

Fast authentication in a collaborative wireless access network

In this paper, we propose a novel inter-domain fast-authentication scheme based on a concept of "trust clouds". A trust cloud is formed among neighbouring access points based on a relationship among the owners of the access points. Fast-authentication for inter-domain sites is achieved through cooperation among the trust cloud members. The approach is distributed without a central authentication server being involved in distributing the security master key to the access points belonging to the trust cloud. We propose two algorithms for mobile visiting nodes to perform authentication at handoff and show through a simulation study that the approach significantly reduces authentication delay compared with traditional server based schemes

Design and analysis of location management schemes for a new light-weight wireless network

With the advances in low-cost wireless networking products, researchers and providers are looking at various alternate approaches to mobile communications that can provide low-cost services, and are easy to set up. These approaches are to coexist with traditional Cellular Networks. To this end, we propose a novel light-weight mobile communication network architecture called Cell-Hopping. Cell-hopping has only base stations interconnected by wireless inter-basestation links (WIBLs) as the network infrastructure. WIBLs support all routing and switching in cell-hopping networks, obviating the need for costly core networks. However, lack of core networks make location management more challenging because: (i) location databases cannot be maintained in the core, (ii) database update consumes precious wireless resource, (iii) signalling can not be supported by the core (no core) among disjoint segments of the network. Consequently, approaches which minimise or eliminate database updates are more suitable for Cell-hopping networks. We provide a primary scheme for location management in Cell-hopping and analytically show the scalability problem. To address the scalability problem, we propose a location caching scheme to be used with the primary scheme. In the caching scheme, tuning the cache timer value is most crucial for the success of the scheme because the timer is the most important control parameter. We present analysis of the location caching scheme, and provide a closed-form expression for the optimum timer value for the location cache entry based on user mobility parameter. Using numerical examples, we show that the signalling cost can be reduced by as much as 80% for reasonable message-to-mobility (MMR) values. Conversely, incorrectly selected timer values can nullify benefits of using the location caching scheme

Reducing signalling overhead in cell-hopping mobile wireless networks using location caches

In this paper, we propose and analyze a timer-based location caching scheme to reduce the signalling cost of on-demand location management in the context of a light-weight cellular wireless network architecture, called a cell-hopping network. The timer value is the most important control parameter of the proposed caching scheme. We derive a closed-form expression as a function of the message-to-mobility ratio (MMR), for the optimum timer value that minimizes signalling cost. Using numerical examples, we show that the signalling cost can be reduced by as much as 80% for reasonable MMR values, if the caching timer is set to the optimum value. Conversely, incorrectly selected timer values can nullify the use of the location cache

Residential gateway discovery mechanism

The traditional use of residential gateways (RGs) is limited to the owners of the RG (residential users) only. The umbrella project on the Collaborative Community Network (CCN) 2 opens up RG infrastructure to the community by enabling wireless access to the infrastructure, thereby permitting broadband Internet sharing within neighbourhoods. Therefore, it is essential that providers (RG owners) have mechanisms in place to protect their RG infrastructure against various security threats that arise due to the nature of wireless transmission and that roaming users (MNs) can efficiently interact with RGs in order to capitalise on their services. In this research efficient and scalable solutions for RG service discovery are proposed, a systematic threat analysis is carried out to identify potential security threats, and finally we conduct a detailed performance evaluation of the proposed solutions which validates our proposal

Optimising expanding ring search for multi-hop wireless networks

Expanding ring search (ERS) is a widely used technique to reduce broadcast overhead in multi-hop wireless networks (e.g., ad-hoc and sensor networks). ERS works by searching successively larger areas in the network centred around the source of broadcast. Network-wide broadcast is initiated only if L successive searches fail. This paper explores if there exists an optimal L that would minimise the broadcast cost of ERS. A theoretical model is developed to analyse the expected broadcast cost as a function of L. Using this model, we show that an optimal L exists for any random network topology. The analytical results are validated through extensive numerical experiments that consider a large number of random network topologies of varying sizes and hop lengths. By tuning the parameter L to the optimum value, broadcast cost can be reduced up to 52% depending on the topology

Performance analysis of expanding ring search for multi-hop wireless networks

Expanding ring search (ERS) is a powerful technique used frequently in multi-hop wireless networks for optimising the broadcast cost of searching. How many times to search using ERS, i.e., the search threshold L, is an interesting open question. Various work found in the literature reports an arbitrary value of the search threshold. In this paper, we analyse the impact of L on the performance of ERS by modeling three different regular network topologies - circular, grid, and hexagonal. We have also carried out a pilot study on nonregular (random) topologies. Our analysis of regular topologies suggests that although it is possible to reduce the network-wide broadcast overhead with ERS by carefully selecting parameter L, the overhead reduction is only marginal. We, however, find that for random topologies, ERS may be very effective in reducing broadcast overhead. We also present guidelines for selecting L for both regular and non-regular topologies

Cell hopping: A lightweight architecture for wireless communications

We propose a novel lightweight cellular wireless network architecture called cell hopping. Unlike traditional cellular networks, cell hopping has base stations interconnected by wireless inter-base station links, WIBLs. WIBLs support all routing and switching in cell hopping networks, obviating the need for costly core networks (or a costly switching infrastructure). Cell hopping utilizes an unlicensed frequency and presents a low-cost, rapidly deployable solution for mobile communications. We discuss various technical challenges that must be addressed before cell hopping can become a reality. In particular, we concentrate on location management. We propose an on-demand location management technique that completely eliminates the need for location databases and periodic updates by mobile stations. We provide a few variations of the location management scheme, and compare their performance through simulation

Empirical performance evaluation of a fast authentication scheme in wireless access networks

Wireless access using contributed access points is fast becoming a reality. Technological means are now available for realizing this “anywhere anytime” low-cost wireless access whereby un-utilized wireless resources can be harnessed to form a collaborative network for public access. The success of such access facilities depend largely on the provisioning of fast authentication among the access points. This is crucial for supporting real-time applications such as Voice Over IP (VoIP). In our earlier work, we had developed an inter-domain fast authentication scheme based on the concept of “trust-clouds”. A trust-cloud is formed among neighbouring access points based on a relationship among the owners of the access points. Fast authentication among these inter-domain sites is achieved through cooperation among the trust-cloud members. In previous work, we theoretically formulated the concept of trust-clouds. In this paper we report on the implementation and experimental results of the “trust-clouds” fast authentication concept on legacy hardware. The experimental results verify that the trust-cloud framework can yield significant delay gains for the authentication process when handing off between administrative domains. It is also shown that no special computing platform is needed to achieve these benefits, indeed our testbed was implemented on low end hardware