Browsing Faculty of Natural Sciences by Subject "Quality of Service"
Now showing items 1-3 of 3
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Ma, Zhen Yu; Tucker, William D. (Telkom, 2008)[more][less]
Abstract: Deaf people want to communicate remotely with sign language. Sign language requires sufficient video quality to be intelligible. Internet-based real-time video tools do not provide that quality. Our approach is to use asynchronous transmission to maintain video quality. Unfortunately, this entails a corresponding increase in latency. To reduce latency as much as possible, we sought to adapt a synchronous video codec to an asynchronous video application. First we compared several video codecs with subjective and objective metrics. This paper describes the process by which we chose x264 and integrated it into a Deaf telephony video application, and experimented to configure x264 optimally for the asynchronous environment. URI: http://hdl.handle.net/10566/511 Files in this item: 1
MaTuckerDeafVideoTelephony2008.pdf (348.1Kb) -
Ma, Zhen Yu; Tucker, William D. (Telkom, 2007)[more][less]
Abstract: The South African Deaf community has very limited telephony options. They prefer to communicate in sign language, a visual medium. Realtime video over Internet Protocol is a promising option, but in reality, the quality is often not enough for the Deaf to be able to understand each other’s sign language. Furthermore, these applications were not design specifically for the Deaf. This paper introduces an asynchronous video chat system to provide better quality video at the expense of increased latency. It determined a codec/transmission protocol combination in the laboratory environment and tested it out with actual Deaf users. This paper will address the results based on comparison between different codecs, transmission protocol on asynchronous video communication for the Deaf. URI: http://hdl.handle.net/10566/486 Files in this item: 1
MaTuckerDeaf2007.pdf (875.1Kb) -
Zulu, Docas Dudu; Tucker, William D. (Telkom, 2010)[more][less]
Abstract: This paper describes work in progress on call capacity optimization for voice over Internet Protocol on wireless mesh networks. In a developing country such as South Africa, evidence has shown that rural inhabitants find it difficult to afford the voice services offered by cellular networks. Voice over Internet Protocol is known for its affordability relative to cellular voice services, therefore deploying such services for rural communities will not only benefit rural inhabitants but also offer economic advantages to service providers. We are interested in the provision of voice services with rural wireless mesh networks. Unfortunately voice on mesh networks can experience packet loss and delays that cause reduction in voice quality. Transmission of small voice packets over wireless mesh networks imposes high overhead that leads to a tremendous decrease in call capacity. Therefore, we aim to study the performance of voice over 802.11 wireless mesh networks and evaluate packet aggregation mechanisms that merge small voice packets into a single large packet, in order to preserve voice quality with more calls. We will implement and evaluate packet aggregations mechanisms on a 'mesh potato' network with iterative cycles of laboratory experiments using a network simulator to collect data for performance evaluation. URI: http://hdl.handle.net/10566/618 Files in this item: 1
ZuluTucker-SATNAC2010.pdf (138.4Kb)
Now showing items 1-3 of 3