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- WLAN (5)
- 802.11b (4)
- Video streaming (3)
- IEEE 802.11 (2)
- QoS (2)
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- Resource usage (2)
- VoIp performance (2)
- WLANs (2)
- 802.11 (1)
- Antennas (1)
- Electronics (1)
- Feeder systems. (1)
- Free bandwidth (1)
- Mpeg-4 video (1)
- Networks (1)
- PBG (1)
- Performance evaluation. (1)
- Photonic band gap (1)
- Photonic crystals (1)
- Quantum dots (1)
- Radio-based network (1)
- Raman (1)
- Single layer (1)
- Sliding window (1)
- Spectroscopy (1)
- Strain (1)
- TCP performance (1)
- VoIP performance (1)
- WMN (1)
- Wireless applications (1)
- Publication
Articles 1 - 12 of 12
Full-Text Articles in Engineering
Experimental Investigation On Voip Performance And The Resource Utilization In 802.11b Wlans, Miroslaw Narbutt, Mark Davis
Experimental Investigation On Voip Performance And The Resource Utilization In 802.11b Wlans, Miroslaw Narbutt, Mark Davis
Conference papers
In a shared medium network like the 802.11b WLAN, predicting the quality of VoIP calls from the resource usage of the wireless medium is highly desirable. Analyzing the bandwidth usage at the L2/MAC layer may be especially useful for potential QoS provisioning and call admission schemes. This paper experimentally investigates the relationship between resource utilization in WLANS and the quality of VoIP calls transmitted over wireless medium. Specifically we evaluate how the amount of free bandwidth influences transmission impairments (i.e. delay, loss and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framework) is calculated by a …
Experimental Investigation Of The Effects Of Background Traffic Loads On Streamed Video Over 802.11b Wlans, Tanmoy Debnath, Nicola Cranley, Mark Davis
Experimental Investigation Of The Effects Of Background Traffic Loads On Streamed Video Over 802.11b Wlans, Tanmoy Debnath, Nicola Cranley, Mark Davis
Conference papers
Video is a frame based media and video streaming is often described as “bursty” which has a large impact on the Quality of Service of the video streaming application over WLAN networks. In this paper the impact of background load on the performance of streaming MPEG-4 video with a video server located on the wired network streaming to wireless client is analysed. We experimentally investigate the performance for both uplink and downlink loads. The performance is measured in terms of the key parameters of bit rate, loss rate and mean delay since these are the primary factors that affect the …
Experimental Analysis Of An 802.11b Wireless Mesh Network, Brian Keegan, Karol Kowalik, Mark Davis
Experimental Analysis Of An 802.11b Wireless Mesh Network, Brian Keegan, Karol Kowalik, Mark Davis
Conference papers
Wireless Mesh Networks (WMNs) are a type of radio-based network which require minimal configuration and infrastructure. They can be built using relatively low cost radio and computing platforms. In this paper we attempt to analyze the performance of a simple WNM using various packet sizes as well as a multi-hop WMN.
Moving A Part-Time Engineering Course To A Student-Centred Paradigm, Kevin Kelly
Moving A Part-Time Engineering Course To A Student-Centred Paradigm, Kevin Kelly
Conference papers
This paper is a further reflection on two conference papers presented at the World Conference for Continuing Engineering Education (WCCEE) in Vienna in April 2006 and National University of Ireland (NUI) Galway Conference: The Challenge of Diversity: Teaching, Support and Student Learning , June 2006. Both conference papers dealt with different aspects of my experiences of the theoretical and pedagogical changes required in re-design and delivery of a part-time engineering programme for the continuing education development of electrical engineers in the workforce.
Gauging Voip Call Quality From 802.11 Wlan Resource Usage, Miroslaw Narbutt, Mark Davis
Gauging Voip Call Quality From 802.11 Wlan Resource Usage, Miroslaw Narbutt, Mark Davis
Conference papers
In this paper we experimentally study the relationship between resource utilization in the wireless LAN and the quality of VoIP calls transmitted over the wireless medium. Specifically we evaluate how its overall capacity is shared between three basic MAC bandwidth components (load, access and free) as the number of VoIP calls increases and how it influences transmission impairments (delay, loss and jitter) and thus call quality. Resource utilization (under the MAC bandwidth components framework) is calculated by a WLAN probe application that passively “sniffs” packets at the L2/MAC layer of the wireless medium and analyses their headers and temporal characteristics. …
The Impact Of Tcp Sliding Window On The Performance Of Ieee 802.11 Wlans, Enrique Roques Gomez, Mark Davis
The Impact Of Tcp Sliding Window On The Performance Of Ieee 802.11 Wlans, Enrique Roques Gomez, Mark Davis
Conference papers
In this paper the TCP sliding window mechanism is experimentally investigated as one of the possible causes of the unfairness often observed as IEEE802.11 wireless LANs. We show how by appropriately sizing the sliding window it is possible to re-introduce fairness into the operation of the WLAN.
Effect Of Free Bandwidth On Voip Performance In 802.11b Wlan Networks, Miroslaw Narbutt, Mark Davis
Effect Of Free Bandwidth On Voip Performance In 802.11b Wlan Networks, Miroslaw Narbutt, Mark Davis
Conference papers
In this paper we experimentally study the relationship between bandwidth utilization in the wireless LAN and the quality of VoIP calls transmitted over the wireless medium. Specifically we evaluate how the amount of free bandwidth decreases as the number of calls increases and how this influences transmission impairments (i.e. delay, loss and jitter) and thus degrades call quality. We show that the amount of free bandwidth is a good indicator for predicting VoIP call quality.
Wideband Dual Polarized Directional Base Station Antenna, Francisco L. Lerma
Wideband Dual Polarized Directional Base Station Antenna, Francisco L. Lerma
Masters
The thesis presents a study of different microwave radiators for wireless applications in the frequency range of 2.2 – 2.5GHz. The performance of microstrip patch antennas and dual polarized dipole antennas were evaluated numerically and experimentally verified. A single microstrip patch and a four- element microstrip array were simulated, fabricated and tested. Simulation was carried out by the finite integration time domain (FITD) method. Polarization diversity is realised using crossed dipoles printed elements. For the crossed dipole elements, two different feed arrangements were studied. Parameters such as return loss, isolation, radiation pattern, gain and bandwidth were measured and found to …
Analysis Of Strain And Intermixing In Single-Layer Ge/Si Quantum Dots Using Polarized Raman Spectroscopy, Anna Baranov, A. V. Federov, Tatiana Perova, R. A. Moore, V. Yam, D. Bouchier, V. Le Thanh, Kevin Berwick
Analysis Of Strain And Intermixing In Single-Layer Ge/Si Quantum Dots Using Polarized Raman Spectroscopy, Anna Baranov, A. V. Federov, Tatiana Perova, R. A. Moore, V. Yam, D. Bouchier, V. Le Thanh, Kevin Berwick
Articles
The built-in strain and composition of as-grown and Si-capped single layers of Ge∕Si dots grown at various temperatures (460–800 °C) are studied by a comparative analysis of the Ge-Ge and Si-Ge modes in the polarized Raman spectra of the dots. A pronounced reduction of the strain and Ge content in the dots after deposition of the cap layer at low temperatures is observed, indicating that strain-induced Si diffusion from the cap layer is occurring. For large dots grown at 700–800 °C the observations are in agreement with a model of the Ge∕Si dot consisting of a Si-rich boundary region and …
Study Of The Behaviour Of Video Streaming Over Ieee 802.11b Wlan Networks, Nicola Cranley, Mark Davis
Study Of The Behaviour Of Video Streaming Over Ieee 802.11b Wlan Networks, Nicola Cranley, Mark Davis
Conference papers
The performance of video streaming over WLAN networks is not only influenced by the state of the network but also by the encoding configuration parameters of the video stream, such as the video content being streamed, how the vide is encoded and how it is transmitted. In this paper, we analyse the unique delay characteristic of video streaming applications in a WLAN environment. We show that the “burstiness” of video is due to the frame-based nature of encoded video. We show how each video frame is transmitted as a burst of packets that is queued at the Access Point causing …
Experimental Comparison Of Wired Versus Wireless Video Streaming Over Ieee 802.11b Wlans, Tanmoy Debnath, Nicola Cranley, Mark Davis
Experimental Comparison Of Wired Versus Wireless Video Streaming Over Ieee 802.11b Wlans, Tanmoy Debnath, Nicola Cranley, Mark Davis
Conference papers
In this paper the performance of streaming MPEG-4 video with a video server located on the wired network streaming to wireless clients is compared with the performance of a video server located in the wireless network streaming to wireless video clients. We experimentally investigate the performance for a number of concurrent video streams with varying video frame sizes, frame rates and packetisation schemes. The performance is measured in terms of the key parameters of bit rate, loss rate and mean delay. We show how that there is a trade-off for these parameters for a wired and wireless located server. We …
Design Of One-Dimensional Composite Photonic Crystals With An Extended Photonic Band Gap, Vladimir Tolmachev, Kevin Berwick
Design Of One-Dimensional Composite Photonic Crystals With An Extended Photonic Band Gap, Vladimir Tolmachev, Kevin Berwick
Articles
A technique for photonic band gap (PBG) extension based on mixing photonic crystals with different lattice constants or filling factors is suggested. For the design of photonic crystals with maximal PBG extension the gap map imposition method is utilized. Gap maps for composite photonic crystals based on Si-air structures are calculated and used to predict optimal structures for fabrication.