Hari Mohan Gupta

Managing the Customer Perceived Service Quality for Cellular Mobile Telephony: An Empirical Investigation

With the liberalization and internationalization in telecommunication, service quality has become an important means of differentiation and path to achieve business success. Such differentiation based on service quality can be a key source of competitiveness for many Indian firms and hence have implications for leadership in such organizations. For the past few years, cellular mobile service sector in India has been experiencing the highest growth rate in terms of subscribers and revenues. With the increasing demands of the customer, cellular mobile sector has become competitive. Despite this, most of the cellular mobile service providers in India are primarily focusing on expanding their customer base and tend to overlook investing in service quality. A thorough review of literature revealed that most of the studies reported on service quality focused on the service delivery aspects, ignoring the role of technical quality. The present study strives to develop a valid and reliable instrument to measure customer perceived service quality incorporating both service delivery as well as technical quality aspects. Through a survey of 225 regular users of cellular mobile services, a seven dimensional service quality instrument is revealed, which is empirically tested for unidimensionality, reliability, and construct validity using confirmatory factor analysis. The resulting validated instrument comprised of dimensions including reliability, responsiveness, assurance, empathy, tangibles, convenience, and customer perceived network quality. Further, the results of the regression analysis highlighted the priority areas of service improvement. The study indicated that among the various dimensions, responsiveness is the best predictor, followed by reliability, customer perceived network quality, assurance, convenience, empathy, and tangibles. Thus, superior performance on the most important dimension, responsiveness may be helpful in providing enhanced quality of service. The major managerial implications of study include the following: The service quality instrument so developed can be used by managers for periodic monitoring of service quality as perceived by customers. The study also provides directions to service providers as to which particular dimension require attention in terms of their importance. This would enable the service providers to focus resources in accordance with the importance of these dimensions. Further, the service quality index derived by aggregating the scores on these dimensions can also be developed, which can be used for benchmarking their performance against competitors. The instrument is developed and validated by collecting data from customers in India. There may be a possibility of cultural differences playing a role in the outcome of the study. Thus, there is a need to explore these results for other developing and developed economies. The future studies may also take into account the factors that influence service quality for corporate customers.

Quality of service parameters in cellular mobile communication

With the rapidly changing technologies, customer needs and increased customer awareness, it becomes imperative to review the Quality of Service (QoS) parameters for cellular mobile communication. An important objective of this study is to develop a model of service quality and a set of dimensions forcomparative evaluation, which could provide useful directions to regulators and service providers. The other objective is to critically appraise, categorise and identify issues for further research based on the analysis of literature, covering both the technical and managerial aspects. Finally, a strong need for empirical study using this integrated approach is emphasised.

A new predictive dynamic priority scheduling in Ethernet passive optical networks (EPONs)

Efficient uplink scheduling in Ethernet passive optical networks (EPONs) is very important for maximizing the network capacity while maintaining the required quality of service (QoS). Several variants of dynamic bandwidth resource allocation have been proposed in recent research literature. However, the available techniques do not fully exploit the elastic properties of the user traffic. In this paper, we explore optimal predictive resource allocation strategies by exploiting the elasticity of QoS-constrained traffic and using the knowledge of traffic patterns of different service classes. We propose a predictive dynamic uplink bandwidth allocation scheme that offers lower access delay and packet loss rate, yet achieves a higher overall network throughput. We formulate a model for determining the traffic burstiness-dependent optimum prediction order that would enhance the quality of prediction with a minimum possible prediction-related processing overhead. We then demonstrate that, in a multi-class access scheduling, with respect to the conventional dynamic allocation strategies, our priority scheduling with judicious prediction of individual traffic classes can enhance the system performance significantly. Our analytic observations are supported by extensive simulation results.

Traffic Model and Performance Analysis of Cellular Mobile Systems for General Distributed Handoff Traffic and Dynamic Channel Allocation

An analytical model for channelized cellular mobile circuit-switched systems that support general arbitrary distributed handoff traffic has been proposed. The model is applicable for a dynamic channel allocation scheme. A 2-D Markov chain is developed, which can be used to compute congestion for all kinds of traffic streams. The proposed model is not restricted by a limited range of user mobility and can be reduced to predict congestion for Poisson-distributed handoff traffic and fixed channel allocation scheme.

Performance Modeling of Cellular Mobile Systems: A Review of Recent Advances

Abstract In this paper, we review some of the earlier studies on performance modeling of cellular mobile systems and their improvements proposed in some recent studies. These studies deal with a number of cellular mobile traffic models for fixed channel allocation and dynamic channel allocation, considering the cases, where user population is either infinite or finite. Further, the modeling of handoff process based on various traffic profile has also been investigated. The proposed traffic models were used for mobility modeling and performance analysis in terms of some Quality of Service (QoS) parameters. We also comment on the future scopes of performance analysis in the context of Green Information and Communication Technologies, which may lead to energy-efficient and environment friendly future cellular mobile systems.

QoS-Aware Downlink Cooperation for Cell-Edge and Handoff Users

In this paper, we present a quality-of-service (QoS)-aware cooperative downlink scheduling approach for cell-edge and handoff users that offers more reliability and higher effective capacity. The cooperation (handoff) region is defined for active handoff users between two adjacent base stations (BSs) as a function of the user QoS requirements and network load. In addition, the proposed technique inherently acquires intercell interference (ICI) coordination by adjusting the position and size of the cooperation window suitably. Numerical results are presented showing reliability, user QoS and capacity gain performance, and the region for cooperative scheduling in a coded communication scenario. Our analysis indicates that cooperation provides relatively less gain in effective capacity, i.e., up to about 40% with respect to noncooperative handoff, when the QoS requirement is loose. On the other hand, when the QoS requirement is more stringent, the effective capacity gain can increase up to nearly 100%. Additionally, we show that, while for applications with a loose QoS requirement the cooperation window size is small, i.e., nearly 1% of the total area of the BSs participating in cooperation, it increases quite significantly, i.e., up to nearly 25%, for the applications with stringent QoS. Although the outage performance of the proposed approach is poorer than the joint transmission mode of a cooperative multipoint scheme in lightly loaded networks, its effective capacity is significantly higher under varying network traffic load and QoS constraints.

Intra-organisational quality measurement: the case of cellular mobile services

The objective of this research is to analyse intra-organisational quality dimensions in the context of cellular mobile services. Initially, dimensions were derived based on the combination of literature review and insights gained through exploratory interviews. This was followed by a questionnaire-based survey administered to professionals working in cellular mobile service providers in India. There were 146 respondents to this survey. The survey items were subjected to exploratory factor analysis, which was followed by confirmatory factor analysis. The instrument was tested for unidimensionality, reliability, construct and criteria related validity. The resulting validated instrument can be used by cellular mobile service providers for periodic monitoring of quality level within their organisation. Further, an internal quality index derived by aggregating the scores can also be developed, which would give an indication of the performance of an organisation and provide directions to managers where the improvement efforts need to be targeted.

A dynamic QoS provisioning call admission control in cellular mobile using fuzzy logic

Call Admission Control (CAC) is a fundamental mechanism used for Quality of Service (QoS) provisioning in cellular mobile networks. An effective CAC scheme needs to be adaptive to the changing traffic patterns and thus dynamic approach is preferred. Unlike the conventional CAC schemes, the present paper proposes a scheme that does not use complicated analytical models. Instead it is based on the fuzzy logic control and supports heterogeneous traffic applications like voice, data, etc. In the proposed mechanism, the amount of guard channels to reserve are controlled dynamically on the basis of varying network parameters like call dropping probability, network load, etc. and also takes into account of diverse classes of traffic applications. Analysis showed that the proposed fuzzy logic-based mechanism demonstrated better performance compared to the fixed channel reservation scheme. The results also revealed that fuzzy logic-based CAC mechanism achieved higher channel utilisation while maintaining the required QoS for different classes of applications.

Full length article: Multiple description transform coded transmission over OFDM broadcast channels

We consider image transmission using multiple description transform coding (MDTC) over orthogonal frequency division multiplexed (OFDM) wireless broadcast channels, where the system may not have any feedback on channel gains. We investigate the redundancy allocation in MDTC-OFDM system, physical layer frequency diversity, and decoding strategies to maximize the quality of reconstruction. Via mathematical analysis, supported by MATLAB simulations, we show that, error resilience of the descriptions can be increased by suitable assignment of coding redundancy in the transform modules at the source, which can be further optimized if the channel characteristics are known at the transmitter. Additionally, the relative performance of the MDTC-OFDM system is studied with respect to a competitive approach, called forward error correction based multiple description coding (MDC) over OFDM, where we show that, for the same redundancy assignment, the MDTC based system performs better under harsh channel conditions.

Energy-efficient transmission of DWT image over OFDM fading channel

In many applications retransmission of lost packets are not permitted. In an OFDM system, due to channel fading, only a subset of carriers are usable for successful data transmission. If the channel state information is available at the transmitter, it is possible to take a proactive decision of mapping the descriptions optimally onto the good subcarriers and discard at the transmitter itself the remaining descriptions, which would have been otherwise dropped at the receiver due to unacceptably high channel errors. In this paper we present a energy saving approach to transmission of discrete wavelet transformation based compressed image frames over the OFDM channels. Based on one-bit channel state information at the transmitter, the descriptions in order of descending priority are assigned to the currently good channels. In order to reduce the system power consumption, the mapped descriptions onto the bad subchannels are dropped at the transmitter. Via analysis, supported by MATLAB simulations, we demonstrate the usefulness of our proposed scheme in terms of system energy saving without compromising the received quality in terms of peak signal-noise ratio.