3 research outputs found
Interoperability of wireless communication technologies in hybrid networks: Evaluation of end-to-end interoperability issues and quality of service requirements
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Hybrid Networks employing wireless communication technologies have nowadays brought closer the vision of communication “anywhere, any time with anyone”. Such communication technologies consist of various standards, protocols, architectures, characteristics, models, devices, modulation and coding techniques. All these different technologies naturally may share some common characteristics, but there are also many important differences. New advances in these technologies are emerging very rapidly, with the advent of new models, characteristics, protocols and architectures. This rapid evolution imposes many challenges and issues to be addressed, and of particular importance are the interoperability issues of the following wireless technologies: Wireless Fidelity (Wi-Fi) IEEE802.11, Worldwide Interoperability for Microwave Access (WiMAX) IEEE 802.16, Single Channel per Carrier (SCPC), Digital Video Broadcasting of Satellite (DVB-S/DVB-S2), and Digital Video Broadcasting Return Channel through Satellite (DVB-RCS). Due to the differences amongst wireless technologies, these technologies do not generally interoperate easily with each other because of various interoperability and Quality of Service (QoS) issues.
The aim of this study is to assess and investigate end-to-end interoperability issues and QoS requirements, such as bandwidth, delays, jitter, latency, packet loss, throughput, TCP performance, UDP performance, unicast and multicast services and availability, on hybrid wireless communication networks (employing both satellite broadband and terrestrial wireless technologies).
The thesis provides an introduction to wireless communication technologies followed by a review of previous research studies on Hybrid Networks (both satellite and terrestrial wireless technologies, particularly Wi-Fi, WiMAX, DVB-RCS, and SCPC). Previous studies have discussed Wi-Fi, WiMAX, DVB-RCS, SCPC and 3G technologies and their standards as well as their properties and characteristics, such as operating frequency, bandwidth, data rate, basic configuration, coverage, power, interference, social issues, security problems, physical and MAC layer design and development issues. Although some previous studies provide valuable contributions to this area of research, they are limited to link layer characteristics, TCP performance, delay, bandwidth, capacity, data rate, and throughput. None of the studies cover all aspects of end-to-end interoperability issues and QoS requirements; such as bandwidth, delay, jitter, latency, packet loss, link performance, TCP and UDP performance, unicast and multicast performance, at end-to-end level, on Hybrid wireless networks.
Interoperability issues are discussed in detail and a comparison of the different technologies and protocols was done using appropriate testing tools, assessing various performance measures including: bandwidth, delay, jitter, latency, packet loss, throughput and availability testing. The standards, protocol suite/ models and architectures for Wi-Fi, WiMAX, DVB-RCS, SCPC, alongside with different platforms and applications, are discussed and compared. Using a robust approach, which includes a new testing methodology and a generic test plan, the testing was conducted using various realistic test scenarios on real networks, comprising variable numbers and types of nodes. The data, traces, packets, and files were captured from various live scenarios and sites. The test results were analysed in order to measure and compare the characteristics of wireless technologies, devices, protocols and applications.
The motivation of this research is to study all the end-to-end interoperability issues and Quality of Service requirements for rapidly growing Hybrid Networks in a comprehensive and systematic way.
The significance of this research is that it is based on a comprehensive and systematic investigation of issues and facts, instead of hypothetical ideas/scenarios or simulations, which informed the design of a test methodology for empirical data gathering by real network testing, suitable for the measurement of hybrid network single-link or end-to-end issues using proven test tools.
This systematic investigation of the issues encompasses an extensive series of tests measuring delay, jitter, packet loss, bandwidth, throughput, availability, performance of audio and video session, multicast and unicast performance, and stress testing. This testing covers most common test scenarios in hybrid networks and gives recommendations in achieving good end-to-end interoperability and QoS in hybrid networks.
Contributions of study include the identification of gaps in the research, a description of interoperability issues, a comparison of most common test tools, the development of a generic test plan, a new testing process and methodology, analysis and network design recommendations for end-to-end interoperability issues and QoS requirements. This covers the complete cycle of this research.
It is found that UDP is more suitable for hybrid wireless network as compared to TCP, particularly for the demanding applications considered, since TCP presents significant problems for multimedia and live traffic which requires strict QoS requirements on delay, jitter, packet loss and bandwidth. The main bottleneck for satellite communication is the delay of approximately 600 to 680 ms due to the long distance factor (and the finite speed of light) when communicating over geostationary satellites.
The delay and packet loss can be controlled using various methods, such as traffic classification, traffic prioritization, congestion control, buffer management, using delay compensator, protocol compensator, developing automatic request technique, flow scheduling, and bandwidth allocation
Molecular profiling of cutaneous squamous cell carcinoma
No full textPhDCutaneous squamous cell carcinoma (cSCC) is the second most common form of non-melanoma skin cancer and accounts for the majority of deaths from this disease. Its incidence is increasing rapidly, contributing significant morbidity to patients and a burden on healthcare resources. The molecular events underlying cSCC development remain largely uncharacterised, despite the well established role of ultraviolet radiation as a principal carcinogen. Genomewide analyses of the genetic changes underlying cSCC development have shown they are subject to large chromosomal aberrations, which often involve whole chromosome arms. Many of these events occur in a high proportion of tumours, yet the genes they target are unknown. In this study, genomewide expression microarray data has been obtained from a series of cSCC and integrated with single nucleotide polymorphism (SNP) microarray data, to provide a comprehensive analysis of the events associated with tumour development. In total, 222 genes were identified as differentially expressed in cSCC, of which, 21% were concordant with copy number changes.
Previous genomewide SNP data of cSCC had identified microdeletions within the PTPRD gene in a subset of tumours (Purdie et al., 2009). This was investigated in further detail and revealed microdeletions in this gene were significantly associated with metastatic cSCC. Sequencing analysis showed 37% of cSCC had a mutation at this locus, which suggests PTPRD is aberrant in a significant proportion of tumours. Decreased expression levels of PTPRD were correspondingly found in moderately and poorly differentiated tumours. The role of PTPRD in skin biology is not known and further functional work is required to elucidate its role in skin cancer.
Taken together, these data provide a valuable insight into the genetic background against which cSCC develop. Furthermore, the association of PTPRD disruption with aggressive tumours may potentially be of future benefit as a prognostic biomarker and therapeutic target
Abstracts of the International Conference on Business, Accounting and Finance 2023: Embracing New Business Paradigm Shifts
Get PDFThis book presents the abstracts of the selected contributions to the second International Academic Conference 2023, held on 25-26 February 2023 by the International University of Malaya-Wales (IUMW), Kuala Lumpur, Malaysia. IAC 2023 is the coming together of researchers and industry. It’s a place to gather and share groundbreaking ideas, discoveries, and experiences on a variety of thought leadership topics covered under this year’s conference theme, “Embracing New Business Paradigm Shifts".
Conference Title: International Academic Conference 2023Conference Acronym: IAC 2023Conference Theme: Embracing New Business Paradigm ShiftsConference Date: 25-26 February 2023Conference Venue: IUMW, MalaysiaConference Organizer: International University of Malaya-Wales, Kuala Lumpur, Malaysi
