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Operating System Based Perceptual Evaluation of Call Quality in Radio Telecommunications Networks. Development of call quality assessment at mobile terminals using the Symbian operating system, comparison with traditional approaches and proposals for a tariff regime relating call charging to perceived speech quality.

Call quality has been crucial from the inception of telecommunication networks.
Operators need to monitor call quality from the end-user¿s perspective, in order to retain
subscribers and reduce subscriber ¿churn¿. Operators worry not only about call quality and
interconnect revenue loss, but also about network connectivity issues in areas where mobile
network gateways are prevalent. Bandwidth quality as experienced by the end-user is equally
important in helping operators to reduce churn.
The parameters that network operators use to improve call quality are mainly from the
end-user¿s perspective. These parameters are usually ASR (answer seizure ratio), PDD (postdial
delay), NER (network efficiency ratio), the number of calls for which these parameters
have been analyzed and successful calls. Operators use these parameters to evaluate and
optimize the network to meet their quality requirements.
Analysis of speech quality is a major arena for research. Traditionally, users¿ perception
of speech quality has been measured offline using subjective listening tests. Such tests are,
however, slow, tedious and costly. An alternative method is therefore needed; one that can be
automatically computed on the subscriber¿s handset, be available to the operator as well as to
subscribers and, at the same time, provide results that are comparable with conventional
subjective scores. QMeter® ¿ a set of tools for signal and bandwidth measurement that have
been developed bearing in mind all the parameters that influence call and bandwidth quality
experienced by the end-user ¿ addresses these issues and, additionally, facilitates dynamic tariff
propositions which enhance the credibility of the operator.
This research focuses on call quality parameters from the end-user¿s perspective. The
call parameters used in the research are signal strength, successful call rate, normal drop call
rate, and hand-over drop rate. Signal strength is measured for every five milliseconds of an
active call and average signal strength is calculated for each successful call. The successful call
rate, normal drop rate and hand-over drop rate are used to achieve a measurement of the overall
call quality. Call quality with respect to bundles of 10 calls is proposed.
An attempt is made to visualize these parameters for better understanding of where the
quality is bad, good and excellent. This will help operators, as well as user groups, to measure
quality and coverage.
Operators boast about their bandwidth but in reality, to know the locations where speed
has to be improved, they need a tool that can effectively measure speed from the end-user¿s
perspective. BM (bandwidth meter), a tool developed as a part of this research, measures the
average speed of data sessions and stores the information for analysis at different locations.
To address issues of quality in the subscriber segment, this research proposes the
varying of tariffs based on call and bandwidth quality. Call charging based on call quality as
perceived by the end-user is proposed, both to satisfy subscribers and help operators to improve
customer satisfaction and increase average revenue per user. Tariff redemption procedures are
put forward for bundles of 10 calls and 10 data sessions. In addition to the varying of tariffs,
quality escalation processes are proposed. Deploying such tools on selected or random samples
of users will result in substantial improvement in user loyalty which, in turn, will bring
operational and economic advantages.

Identiferoai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/5479
Date January 2012
CreatorsAburas, Akram
ContributorsGardiner, John G., Al-Mashouq, K.
PublisherUniversity of Bradford, School of Engineering, Design and Technology
Source SetsBradford Scholars
LanguageEnglish
Detected LanguageEnglish
TypeThesis, doctoral, PhD
Rights<a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>.

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