Computer Engineering Commons^™

An Adaptive Packet Aggregation Algorithm (Aam) For Wireless Networks, Jianhua Deng

Doctoral

Packet aggregation algorithms are used to improve the throughput performance by combining a number of packets into a single transmission unit in order to reduce the overhead associated with each transmission within a packet-based communications network. However, the throughput improvement is also accompanied by a delay increase. The biggest drawback of a significant number of the proposed packet aggregation algorithms is that they tend to only optimize a single metric, i.e. either to maximize throughput or to minimize delay. They do not permit an optimal trade-off between maximizing throughput and minimizing delay. Therefore, these algorithms cannot achieve the optimal network …

An Autonomous Channel Selection Algorithm For Wlans, Fuhu Deng

Doctoral

IEEE 802.11 wireless devices need to select a channel in order to transmit their packets. However, as a result of the contention-based nature of the IEEE 802.11 CSMA/CA MAC mechanism, the capacity experienced by a station is not fixed. When a station cannot win a sufficient number of transmission opportunities to satisfy its traffic load, it will become saturated. If the saturation condition persists, more and more packets are stored in the transmit queue and congestion occurs. Congestion leads to high packet delay and may ultimately result in catastrophic packet loss when the transmit queue’s capacity is exceeded. In this …

Judging Emotion From Low-Pass Filtered Naturalistic Emotional Speech, John Snel, Charlie Cullen

Conference papers

In speech, low frequency regions play a significant role in paralinguistic communication such as the conveyance of emotion or mood. The extent to which lower frequencies signify or contribute to affective speech is still an area for investigation. To investigate paralinguistic cues, and remove interference from linguistic cues, researchers can low-pass filter the speech signal on the assumption that certain acoustic cues characterizing affect are still discernible. Low-pass filtering is a practical technique to investigate paralinguistic phenomena, and is used here to investigate the inference of naturalistic emotional speech. This paper investigates how listeners perceive the level of Activation, and …

Adaptive Ofdm For Wireless Interconnect In Confined Enclosures, Vit Sipal, Javier Gelabert, Christopher J. Stevens, Ben Allen, David Edwards

Articles

This letter considers and recommends OFDM with adaptive subcarrier modulation as a suitable candidate for wireless UWB communication in computer chassis. A rigorous measurement campaign studies the guaranteed spectral efficiency. It concludes that enhancement of the existing WiMedia OFDM systems with a bandwidth of 528 MHz in order to support adaptive OFDM would enable data-rates above 1 Gbps over short ranges, i.e. the spectral efficiency would be doubled. Moreover, the guaranteed spectral efficiency is shown to increase with bandwidth, i.e. the guaranteed data-rate increases better than linearly with bandwidth.

A Performance Analysis Of Ws-* (Soap) And Restful Web Services For Implementing Service And Resource Orientated Architectures, Philip Markey, Gary Clynch

Conference Papers

The past number of years have seen the emergence of Service-Oriented Architectures as a dominant architecture for implementing enterprise scale distributed systems. Two main styles of SOA exist, namely SOAP based services and RESTful services. There has been much comment and debate on the pros and cons of each approach to implementing a SOA, a lot of which has surrounded the performance characterictcs of both approaches. In this paper, the authors presents the results of a performance analysis that was conducted on a set of test SOA scenarios implemented using both SOAP and RESTful approaches; in particular the caching capabilities …

Using Grounded Theory To Develop A Framework For Software Testing Best Practice In A Telecommunications Company, David Hendrick

Dissertations

Software testing is a key part of the software development process, irrespective of the development methodology being followed. Estimates suggest that testing can account for more than 50% of the cost of a software development project. However, the cost of inadequate testing or verifying software can be far greater; this can result in losses that could total more than 10% of an organisation’s turnover. It is clear that software testing is essential; but while many companies implement different forms of testing, there is often no structure or best practice followed to this testing. There appears to be a gap in …

Exploring Spatial Business Data: A Roa Based Ecampus Application, Thanh Thoa Pham Thi, Linh Truong- Hong, Junjun Yin, James Carswell

Conference papers

In "Smart" environments development, providing users with search utilities for interacting efficiently with web and wireless devices is a key goal. At smaller scales, Google Maps and Google Earth with satellite and street views have helped users for querying general information at specific locations. However, at larger local scales, where detailed 3D geometries linked to business data are needed, there is a recognized lack of related information and functionality for in depth exploration of an area. Linking spatial data and business data helps to enrich the user experience by fulfilling more task specific user needs. This paper presents an eCampus …

Expecting The Unexpected : Measuring Uncertainties In Mobile Robot Path Planning In Dynamic Envionments, Yan Li, Brian Mac Namee, John D. Kelleher

Conference papers

Unexpected obstacles pose significant challenges to mobile robot navigation. In this paper we investigate how, based on the assumption that unexpected obstacles really follow patterns that can be exploited, a mobile robot can learn the locations within an environment that are likely to contain obstacles, and so plan optimal paths by avoiding these locations in subsequent navigation tasks. We propose the DUNC (Dynamically Updating Navigational Confidence) method to do this. We evaluate the performance of the DUNC method by comparing it with existing methods in a large number of randomly generated simulated test environments. our evaluations show that, by learning …

Detailed Comparative Analysis Of Pesq And Visqol Behaviour In The Context Of Playout Delay Adjustments Introduced By Voip Jitter Buffer Algorithms, Andrew Hines, Peter Pocta, Hugh Melvin

Conference papers

The default best-effort Internet presents significant challenges for delay-sensitive applications such as VoIP. To cope with non determinism, receiver playout strategies are utilised in VoIP applications that adapt to network condition. Such strategies can be divided into two different groups, namely per-talkspurt and per-packet. The former make use of silence periods within natural speech and adapt such silences to track network conditions, thus preserving the integrity of active speech talkspurts. Examples of this approach are described in [1, 2]. Per packet strategies are different in that adjustments are made both during silence periods and during talkspurts by time-scaling of packets, …

Robustness Of Speech Quality Metrics To Background Noise And Network Degradations: Comparing Visqol, Pesq And Polqa, Andrew Hines, Naomi Harte, Jan Skoglund, Anil Kokaram

Conference papers

The Virtual Speech Quality Objective Listener (ViSQOL) is a new objective speech quality model. It is a signal based full reference metric that uses a spectro-temporal measure of similarity between a reference and a test speech signal. ViSQOL aims to predict the overall quality of experience for the end listener whether the cause of speech quality degradation is due to ambient noise, or transmission channel degradations. This paper describes the algorithm and tests the model using two speech corpora: NOIZEUS and E4. The NOIZEUS corpus contains speech under a variety of background noise types, speech enhancement methods, and SNR levels. …

Monitoring The Effects Of Temporal Clipping On Voip Speech Quality, Andrew Hines, Naomi Harte, Jan Skoglund, Anil Kokaram

Conference papers

This paper presents work on a real-time temporal clipping monitoring tool for VoIP. Temporal clipping can occur as a result of voice activity detection (VAD) or echo cancellation where comfort noise in used in place of clipped speech segments. The algorithm presented will form part of a no-reference objective model for quantifying perceived speech quality in VoIP. The overall approach uses a modular design that will help pinpoint the reason for degradations in addition to quantifying their impact on speech quality. The new algorithm was tested for VAD compared over a range of thresholds and varied speech frame sizes. The …

Retaining The People Who Know Your Business Exploring Knowledge Sharing As A Tool To Improve Employee Retention In The Hotel Sector, Vincent Mckenna

Dissertations

The retention of core workers in the hotel/hospitality sector is a key challenge for human resource management, organisational strategies and operational effectiveness. The purpose of this research was to investigate and evaluate the impact of the introduction of knowledge sharing tools/techniques and change in work practice on the retention attitudes of knowledge workers in two context specific environments. Problems relating to the retention of knowledge workers are not confined to Ireland and are shown in this project to be a global phenomenon.

This research project is based on a knowledge audit of core knowledge workers/assets in two context specific environments …

Applying Data Visualisations To Open New Perspectives In Birdwatching, Frank Kendlin

Dissertations

Advances in data analytics for big data have affected many different domains and are providing new insights from these data for their respective communities. One such community is conservation science. A part of section of this community, ornithologists and bird conservationists has at its disposal millions of volunteers willing to contribute to a new ‘big’ data set. This can be achieved by means of new technology and the use of citizen science. This is already underway in North America through the excellent work of the Cornell Laboratory of Ornithology (CLO). This institute has harnessed the technology and the people and …

A New Simplified Federated Single Sign-On System, Chen Liang

Masters

The work presented in this MPhil thesis addresses this challenge by developing a new simplified FSSO system that allows end-users to access desktop systems, web-based services/applications and non-web based services/applications using one authentication process. This new system achieves this using two major components: an “Authentication Infrastructure Integration Program (AIIP)" and an “Integration of Desktop Authentication and Web-based Authentication (IDAWA)." The AIIP acquires Kerberos tickets (for end-users who have been authenticated by a Kerberos single sign-on system in one net- work domain) from Kerberos single sign-on systems in different network domains without establishing trust between these Kerberos single sign-on systems. The …

A Window Of Opportunity: Assessing Behavioural Scoring, Kenneth Kennedy, Brian Mac Namee, Sarah Jane Delany, Michael O'Sullivan, Neil Watson

Articles

After credit has been granted, lenders use behavioural scoring to assess the likelihood of default occurring during some specific outcome period. This assessment is based on customers’ repayment performance over a given fixed period. Often the outcome period and fixed performance period are arbitrarily selected, causing instability in making predictions. Behavioural scoring has failed to receive the same attention from researchers as application scoring. The bias for application scoring research can be attributed, in part, to the large volume of data required for behavioural scoring studies. Furthermore, the commercial sensitivities associated with such a large pool of customer data often …