Cellular Telecommunications Research Articles

EMBEDDED ANTENNA FOR METALLIC HANDHELD COMMUNICATION DEVICES

In this study, a quad-band folded slot antenna with a monopole feed line embedded in a conductive housing structure (the LCD bracket of a mobile phone) is proposed. The performance of the proposed antenna is evaluated through simulation and measurement, demonstrating that it can provide total radiation e-ciencies of more than 40% in the EGSM900, DCS, PCS, and WCDMA1 bands. Over these four bands, the total radiated power (TRP) of a prototype mobile phone using the antenna is 28.5, 27.1, 27.5, and 21dBm, respectively, while the total isotropic sensitivity (TIS) is 102.7, 104.3, 103.8, and 107.3dBm, respectively; all of these values satisfy Cellular Telecommunication and Internet Association (CTIA) requirements for over-the-area-(OTA) testing standards. The radiation performance of the proposed antenna in the calling mode is tested and shown to be within satisfactory limits; similarly, the speciflc absorption rates (SARs) of the prototype mobile phone are also found to be within standard SAR limits.

Some Features of Radio-Spectral Diagnostics of Random Media via PM and PRM Oscillations

Due to the development of satellite, mobile, cellular, and optical telecommunication systems, a special attention is paid to broad band frequency signals, like signals with wide spectrum, when frequency band of the transmitting signal may be wider than frequency band of the transmitted signal itself. For many telecommunication systems, the ability of transmitting information to several users simultaneously via one and the same channel is very important. A number of methods are applied for this purpose, for instance: the frequency modulation (FM) of the carrier signal (the method of frequency division of transmitting channel), phase modulation (PM) of the carrier signal or pseudo-random modulation (PRM) of the carrier signal. In the conditions of increasing demands on communication systems, the question of creating multi-user systems became very actual. In all cases it is necessary to provide high quality connection on longer distance so that the universal standards should not be violated.

Growing Existing Customers’ Revenue Streams through Customer Referral Programs

Customer referral programs are an effective means of customer acquisition. By assessing a large-scale customer data set from a global cellular telecommunications provider, the authors show that participation in a referral program also increases existing customers’ loyalty. In a field experiment, recommenders’ defection rates fell from 19% to 7% within a year, and their average monthly revenue grew by 11.4% compared with a matched control group. A negative interaction between referral program participation and customer tenure reveals that the loyalty effect of voicing a recommendation is particularly pronounced for newer customer–firm relationships. A laboratory experiment further demonstrates that referral programs with larger rewards strengthen attitudinal and behavioral loyalty, whereas smaller rewards affect only the behavioral dimension. This article contributes to our theoretical understanding of the roles played by the commitment–consistency principle and positive reinforcement theory as mechanisms underlying the effectiveness of customer referral programs.

Femto Cells-A New Generation Cellular Stations

This paper provides a cost effective method for cellular telecommunications base stations that can be installed in residential or business environments either as single stand-alone items or in clusters to provide improved cellular coverage within a building. Data transmission, good signal strengths within buildings, increase in system capacity and data rates are some of the issues been discussed in this review work. The increasing demand for higher data rates in cellular networks has resulted in a trend to smaller cell sizes (Femto cells) and Pico-cellular hot spot coverage. As a result the user can have the advantage of better coverage for additional services, cost benefits and also the network operator, the use of Femto cells provides a very cost effective means of improving coverage, along with linking users to the network, and providing additional revenue from the provision of additional services. Femto cells deployed in the macro cell significantly improve the indoor coverage and provide better user experience. This article summarizes about the network architecture of Femto cells and the issues involved with it. Also it describes about the methods to overcome the issues

835 MHz 및 1,800 MHz 대역에서 인체의 전기적 특성을 가지는 한국인 손 모양의 팬텀 제작

휴대전화의 이용이 증가하면서, 손에 미치는 전자파의 영향에 대한 관심이 증가하고 있다. IEC TC106에서도 휴대전화의 전자파 인체 노출량 평가 방법 표준에 손 영향을 반영하기 위하여 국제적인 교류 연구가 활발하게 진행되고 있다. 현재 상용화된 손 팬텀은 평균 서양인 손을 이용하고 있을 뿐만 아니라, 한 가지 형태의 파지(把持)만 가능하기 때문에, SAR 측정 결과에 대한 분석에 제한이 많은 실정이다. 손의 영향을 제대로 분석하기 위해서는 다양한 형태의 파지가 가능한 손 팬텀이 필요하다. 또한, 국내 환경에 맞는 손 팬텀의 개발이 필수적이다. 본 논문에서는 다양한 형태의 파지가 가능한 835 MHz 대역과 1,800 MHz 대역의 한국인의 젤리형 손 팬텀을 제작하였다. 제작된 손 팬텀의 전기적 특성은 비유전율과 도전율이 CTIA(미국이동통신산업협회) 권고 기준 값의 <TEX>${\pm}10%$</TEX>이내로서, CTIA에서 제시하는 오차 기준(<TEX>${\pm}20%$</TEX>)보다 더 우수한 특성을 나타냈다. 또한, 손 팬텀의 3D CAD(3차원 컴퓨터 이용 설계) 파일을 개발하여 손에 의한 SAR 영향 분석을 위한 시뮬레이션에서 활용할 수 있도록 하였다. 본 연구를 통해 제작된 젤리형 손 팬텀과 3D 파일은 휴대 전화의 손 영향에 대한 연구에 유용하게 이용될 수 있을 것으로 본다. Interest of the hand effect on the electromagnetic wave are internationally increasing with the increase of the use of the mobile phone. IEC TC106(International Electrotechnical Commission, Technical Committee 106) promotes international research exchange program in order to reflect the effect of human hands in the standard assessment method of human exposure dosimetry by the electromagnetic wave of mobile phones. Since current commercialized hand phantom is manufactured by taking into account the average size of westerners and provides only one grip posture, it imposes many restrictions on the accurate SAR measurement. Therefore, the development of proper hand phantom accounting for domestic situation and various grip posture capability is essential in order to analyze the accurate effect of human hand on the exposure estimation. In this paper, a jelly hand phantom suitable for Korean was manufactured with various grip posture capability at 835 MHz and 1,800 MHz bands. Although the tolerances of permittivity and conductivity of the manufactured hand phantom are with <TEX>${\pm}10%$</TEX> each, it was much less than CTIA(Cellular Telecommunication Industry Association) tolerance of <TEX>${\pm}20%$</TEX> at both bands. Its 3D CAD(3 Dimensional Computer Aided Design) file which was developed can be utilized for the simulation of human hand effect on SAR measurement of mobile phones. The findings in this study can be utilized for the analysis of human hand effect on SAR measurement of a mobile phone.

Order without hierarchy - the innovation ecology of a standard developing organization

A Standard-developing organizations (SDO) is a voluntary inter-organizational collaborations to develop a global compatibility standard for an open modular system. A SDO is characterized by equal membership and hence lacks a hierarchy that assigns resources and tasks. Member organizations work jointly on innovations of the technological system, resulting in a two-mode innovation network between organizations and innovations. I study the emerging order in this network despite the lack of hierarchy. In particular I examine the existence and form of the emerging order, the underlying mechanism leading to its formation and its stability. I apply recent methods from ecological mutual systems as plant-pollinator networks to the innovation network of cellular telecommunications from 2001 to 2010. The match of organizations' resources with those required to develop innovations as tie formation mechanism explains basic structural properties as degree distribution and nestedness of the network. While the innovation network's nestedness is rather stable over time, individual organizations can change dramatically as the catch-up of Chinese firms illustrates.

Directions for future cellular mobile network architecture

Despite the extraordinary success of the cellular mobile telecommunications industry, many of the underlying design strategies and service assumptions that have served us arguably well over the past four decades may benefit from a fresh new look. Even today’s LTE (Long–Term Evolution), which is designed to meet the demands of modern broadband Internet packet connectivity, nonetheless draws heavily on the legacy of cellular’s circuit–oriented origins. Its heavy reliance on fine–grained tunnels and hard–state signaling protocols, for example, imposes performance penalties and cost burdens that may not be inevitable if hard–earned lessons are incorporated in the coming years. In this paper we describe a fresh approach to cellular network architecture. Inspired by past and present ideas and experiences by others and ours, we propose fundamental principles to guide the development of efficient and flexible network architecture, able to serve the still unknown needs and preferences of future users. We offer an example of a network built on those principles and suggest how we can manage the evolution from today’s networks to an architecture better suited to the decades ahead.

M-health for health behaviour change in resource-limited settings: applications to HIV care and beyond

Of the new advanced information and communication technologies, cellular telecommunication networks and mobile phones have reached far more people than any other, especially in de -veloping countries. Although internet use has also increased substantially in recent years, in 2011 26% of the people in developing countries had internet access, whereas 79% had mobile or cellular phone subscriptions.

Neighboring Cell Search for LTE Systems

Long term evolution (LTE) is considered to be a key technology for the next generation of cellular telecommunications. In LTE systems, each user equipment (UE) detects the surrounding cells by searching their identities (IDs) in the synchronization channels of the received waveform. Searching and tracking neighboring cells is important for cellular network management, such as handover and base station cooperation. In this paper, we establish a general framework for neighboring cell search (NCS) in LTE systems. In particular, we derive sufficient signal metrics (SSMs) for NCS under various channel conditions, and develop NCS algorithms based on the SSMs, which optimally combine multiple observations over space and/or time. Moreover, we develop a statistical model for NCS using probability analysis. The performance of NCS algorithms is characterized in terms of the number of detected cells and the cell detection probability, and simulation results validate the effectiveness of the proposed algorithms.

Insolvency modeling in the cellular telecommunication industry

In this article, we test several models (decision tress and neural networks) to predict customer insolvency at one of the cellular telecommunication operator in Poland. In comparison to previous studies on customer insolvency, our research presents novelty in the following areas. First of all, we deal with cellular telecommunication customers who use services without paying dues (the literature show the studies that dealt mainly with fixed line operators or banking industry). Secondly, we have a large dataset with 205 explanatory variables derived from the database (previous studies dealt with smaller datasets). Thirdly, we test the quality of the models three months after the estimation with lift and ROC curves to assess the models performance over the time.The main findings from the research are twofold: (1) artificial neural networks perform well when modeling the customer’s insolvency and the best model can capture significant amount of money owed by insolvent customers; (2) decision trees get old quickly and their performance decrease over the time in the top percentiles of the score.

Modeling and design of a bi-access tri-band antenna combining different radiating structures based on modal analysis of resonant cavity

A new design method for multi-access antennas is presented. This method is based on a modal analysis assuming the microstrip antennas as a resonant cavity. Using this cavity approach, the eigenmodes perturbation induced by the cavity deformation (adding slots or short circuits) is studied. As an application, a solution of multi-access antenna with two ports, with operating frequency bands centered approximately on digital cellular system (DCS) and universal mobile telecommunication system (UMTS)/Wi-Fi standards is developed. These two ports are isolated using the previous original design method. In addition to the design method, the innovation of the structure resides on its application in terms of flexibility, reconfigurability, and portability for the future development of a unique system that allows cross services where telephony joined multimedia and online services. The design method and the performances are validated through comparisons between simulations and measurements.

Business model requirements and challenges in the mobile telecommunication sector

The telecommunications business is undergoing a critical revolution, driven by innovative technologies, globalization and deregulation. Cellular networks and telecommunications bring radical changes to the way telecom businesses are conducted. Globalization, on the other hand, is tearing down legacy barriers and forcing monopolistic national carriers to compete internationally. Moreover, the noticeable progress of many countries towards deregulation coupled with liberalization is significantly increasing telecom market power and allowing severe competition. The implications of this transition have changed the business rules of the telecom industry. In addition, entrants into the cellular industry have had severe difficulties due to inexistent or weak business models (BMs). Designing a BM for a mobile network operator (MNO) is complex and requires multiple actors to balance different and often conflicting design requirements. Hence, there is a need to enhance operators’ ability in determining what constitutes the most viable BM to meet their strategic objectives within this turbulent environment. In this article, the authors identify the main mobile BM dimensions along with their interdependencies and further analysis provides MNOs with insights to improve their BMs in this new ‘boundary-less’ landscape.

라그랑지안 기반의 휴리스틱 기법을 이용한 셀룰러 모바일 네트워크의 설계

Cellular network is comprised of several base stations which serve cellular shaped service area and each base station (BS) is connected to the mobile switching center (MSC). In this paper, the configuration modeling and algorithm of a cellular mobile network with the aim of minimizing the overall cost of operation (handover) and network installation cost (cabling cost and installing cost of mobile switching center) are considered. Handover and cabling cost is one of the key considerations in designing cellular telecommunication networks. For real-world applications, this configuration study covers in an integrated framework for two major decisions: locating MSC and assigning BS to MSC. The problem is expressed in an integer programming model and a heuristic algorithm based on Lagrangian relaxation is proposed to resolve the problem. Searching for the optimum solution through exact algorithm to this problem appears to be unrealistic considering the large scale nature and NP-Completeness of the problem. The suggested algorithm computes both the bound for the objective value of the problem and the feasible solution for the problem. A Lagrangian heuristics is developed to find the feasible solution. Numerical tests are performed for the effectiveness and efficiency of the proposed heuristic algorithm. Computational experiments show that the performance of the proposed heuristics is satisfactory in the quality of the generated solution.

Service Quality and Customers preference of Cellular Mobile Service Providers

A research study was conducted with an objective to understand the Indian consumers’ perception choice in selecting cellular mobile telecommunication service providers. Consumers’ perception is widely varied in accordance with the Communication quality, call service, facilities, price, customer care and service provider’s attributes. A structured questionnaire was developed to collect the required primary data from the consumers. Collected data were analysed, reliability and factor analysis were carried out. The outcome of this research shows a comprehensively integrated framework to understand the relationships among several dimensions. The study shows communication and price were most influential and most preferential factors in selecting telecommunication service provider. However, product quality and availability has a significant impact on consumer perception choice in selecting cellular mobile service provider.

Optimal Mobile Switching Center Positioning and Cells Assignment Using Lagrangian Heuristic

This paper deals with the configuration of a wireless network with the aim of minimizing the overall cost of both operation and network installation. The trade-off between the operation cost and the installation cost is the key consideration when designing cellular telecommunication networks, and can save costs and improve the performance of the network. In this paper, we propose an integrated framework for selecting Mobile Switching Center (MSC) among the candidate MSCs and assigning Base Stations (BSs) to the selected MSCs with the objective function of minimizing the cost of MSC setup, BS to MSC cabling, as well as the cost of handover. Capacity constraint for the selected MSC is also considered in the problem. The problem is expressed in an integer programming model and the Lagrangian relaxation method is proposed to solve the problem by dualizing some constraints. The Lagrangian relaxed problem is decomposed into subproblems that can be resolved optimally. The Lagrangian heuristic algorithm is suggested to find feasible solutions to the original problem. Computational experiments are performed to test the effectiveness and efficiency of the proposed heuristic algorithm. In the experiments, Lagrangian bounds on the optimal solution are used to show the effectiveness of the algorithm. The results of the proposed algorithm are also compared with those of some conventional meta-heuristics, Tabu search (TS) and Genetic algorithm (GA). The computational experiments show that the performance of the proposed heuristics is satisfactory in both the speed and the quality of the solution generated.

Ranking the strategic actions of Iran mobile cellular telecommunication using two models of fuzzy QFD

Mobile cellular telecommunication success in target markets first requires ranking the customer’s expectations and then prioritizing the engineering characteristics (ECs) to meet the expectations. In this paper, two prioritization models based on quality function deployment (QFD) are developed to rank the strategic actions (SAs), or the ECs of Iran mobile cellular telecommunication. QFD is a widely used customer-driven tool for which the success of its applications may be the result of some of its benefits, such as greater customer focus. It uses a matrix called House of Quality (HOQ) to translate Customer Attributes (CAs) into ECs. However, due to the high degree of subjectivity in constructing the HOQ, the application of fuzzy logic provides an efficient tool to handle the subjective assessments. On the other hand, taking into consideration the gap between the current state and the positive ideal state for each CA, TOPSIS is used to rank CAs in a first model. In addition, in a second model, using the analytic hierarchy process (AHP), more criteria are taken into consideration in ranking CAs. Also, a fuzzy utility factor, B j , is used to rank SAs in both models. Both presented models have the ability to capture the vagueness of human thinking style, and let customer oriented organizations, such as MCI, derive benefits from the voice of the customer (VOC) in a more expressive way.

Look-Ahead Strategies Based on Store-Carry and Forward Relaying for Energy Efficient Cellular Communications

With the increasing availability of Internet type services on mobile devices and the attractive flat rate all-you-can-eat billing system, cellular telecommunication networks are experiencing a tremendous growth in data usage demand. However, there are increasing concerns that current network deployment trends (including more efficient radio access techniques and increased spectrum allocation strategies), will be unable to support the increased Internet traffic in a sustainable way. The delay tolerant nature of mobile Internet traffic allows for a large degree of flexibility in optimizing network performance to meet different design objectives and it’s a feature that has mostly gone unexplored by the research community. In this paper, we introduce a novel message forwarding mechanism in cellular networks that benefits from the inherent delay tolerance of Internet type services to provide flexible and adjustable forwarding strategies for efficient network operation while guaranteeing timely deliveries. By capitalizing on the elasticity of message delivery deadlines and the actual mobility of nodes inside the cell, considerable performance gains can be achieved by physically propagating information messages within the network.

Churn models for prepaid customers in the cellular telecommunication industry using large data marts

In this article, we test the usefulness of the popular data mining models to predict churn of the clients of the Polish cellular telecommunication company. When comparing to previous studies on this topic, our research is novel in the following areas: (1) we deal with prepaid clients (previous studies dealt with postpaid clients) who are far more likely to churn, are less stable and much less is known about them (no application, demographical or personal data), (2) we have 1381 potential variables derived from the clients’ usage (previous studies dealt with data with at least tens of variables) and (3) we test the stability of models across time for all the percentiles of the lift curve – our test sample is collected six months after the estimation of the model. The main finding from our research is that linear models, especially logistic regression, are a very good choice when modelling churn of the prepaid clients. Decision trees are unstable in high percentiles of the lift curve, and we do not recommend their usage.

The application of real option valuation techniques in the cellular telecommunication industry in South Africa

The purpose of this paper is to examine whether real option valuation techniques can be used by cellular telecommunication operators in South Africa when making capital investment decisions in next-generation service-orientated architectures. Prior studies, in other parts of the world, recommend the use of real option valuation techniques by telecommunication operators when conducting capital budgeting. In this study, both Black-Scholes and Binomial models are used to examine their effectiveness in valuing capital investments within a cellular telecommunication industry in South Africa. Results show that real option valuation techniques are effective in analysing investments in cellular telecommunication industry. Their strengths are mostly demonstrated when determining the value of strategic options that are added to traditional (base-case) net present value. Summary and conclusions are provided.

Income as a determinant of the acquisition of cellular products and services by tertiary students

Cellular phones are not seen as a luxury for a select few but have become a necessity for every person and obtained for a multitude of reasons (Mutula, 2002). Students, similar to other consumers, use and consume cellular communication products and services. Profitable opportunities exist should products and services be developed to meet the specific expectations and requirements of the student cellular communication market. One element that has an influence is their available income. Information on the influence of income can help cellular telecommunication ventures to develop marketing plans for the student market. The purpose of this study was to determine whether there were any differences between high- and low-income group students in their selection of a cellular phone brand or network operator. Two hypotheses were set to determine if there would be any significant differences between the two income groups once independent decision making was possible.