Browsing by Author "Schoonwinkel, Daniel"
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- ItemPractical measurements of Wi-Fi Direct in content sharing, social gaming android applications(Stellenbosch : Stellenbosch University, 2016-03) Schoonwinkel, Daniel; Van Rooyen, G. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Wi-Fi Direct is a recent expansion to the very successful 802.11 Wi-Fi technology. According to Wi-Fi Alliance, Wi-Fi Direct is being broadly adopted, among others by Google’s Android (since version 4.0 Ice Cream Sandwich). However, to the authors’ knowledge no formal testing of Wi-Fi Direct throughput, latency, packet loss and energy use on smartphones has been performed. This thesis presents practical measurements of Wi-Fi Direct capabilities on Android smartphones in practical use-case driven applications. It was found that Wi-Fi Direct would be well suited to content sharing applications and possibly also gaming applications. Furthermore, tests showed that Wi-Fi Direct is more sensitive to communication range and uses more energy compared to standard Wi-Fi. However, with some improvements to this technology, also discussed in this thesis, and on-going development in Android, Wi-Fi Direct could become a reliable and ubiquitous device-to-device communication medium.
- ItemQuantification and improvement of state consistency in a virtual environment under adverse network conditions(Stellenbosch : Stellenbosch University, 2020-03) Schoonwinkel, Daniel; Engelbrecht, H. A.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: Virtual Reality, Augmented Reality and Virtual Environments (VE) all share a critical requirement: the virtual environment needs to be consistent and interactive, in order to provide the realism that enables a user to be immersed in an environment other than their own. State in Virtual Environment is the information that needs to be disseminated to every user’s interface in order to render the virtual environment. Ensuring that each user has a live and consistent view of the VE, requires that each user receives the most recent changes to the VE. Interactivity in the VE increases the amount of information that must be disseminated between interacting users, and also means that updates must be sent with low latency to ensure state consistency. Furthermore, in order to complete the immersion into the virtual world, the user must be disconnected from her current world: by using wireless communication, the user can be untethered and free to move around to experience the virtual world. Wireless virtual reality is thus seen as a necessity for virtual immersion. As the next generation of mobile wireless communication, the 5G specification promises high throughput of up to 10Gbps data rate, 1 millisecond latency and ultra-high reliability coupled with a 100-fold increase in the number of connected devices. 5G technology could finally enable distributed, fully immersive, wireless Virtual Reality. Wireless communication is susceptible to interference and therefore prone to information loss. In order to understand how wireless loss will affect state consistency, we need to evaluate state degradation under adverse network conditions, such as loss, network delay and bandwidth limitations. In this dissertation we quantify the state consistency by using VAST, an existing VE implementation, and the Mininet network emulator, which allows controlling different adverse network conditions. We found that under most adverse network conditions, the state consistency degrades significantly. We also found that UDP was less sensitive to adverse conditions than TCP. In order to improve the state consistency, we propose a network coding based packet loss mitigation protocol that uses the UDP transport protocol. We term this new protocol UDPNC and show that it is successful at improving state consistency and also performs well when network delay is introduced. However, we show that UDPNC requires significantly more bandwidth than other network transport protocols and suffers in scenarios where bandwidth is limited. However, assuming that a high bandwidth wireless connection is available, such as provided by 5G mobile or Wi-Fi 802.11ac, we argue that the extra bandwidth would not present a significant cost to improving state consistency.