Implementing a multi-access Push to Talk system and analysing user experience

Pikapuhe on uusi, pikaviestin tyyppinen matkapuhelinpalvelu. Pikapuhetta voidaan käyttää kahdenkeskisiin ja ryhmäpuheluihin. Pikapuhe ei ole menestynyt odotetulla tavalla. Tässä työssä toteutettiin moniliityntäinen pikapuhe-järjestelmä ja siitä kerättiin käyttäjäkokemuksia. Järjestelmään voitiin liittyä sekä matkapuhelimen että tietokoneen pikapuhe-sovelluksilla. Testiin osallistui 14 testaajaa ja testi kesti kaksi kuukautta. Testin aikana ja sen jälkeen osallistujat vastasivat kyselyihin. Yhtenä tutkimusmenetelmänä käytettiin myös muuttotilanteen tarkkailua. Muuttoon osallistui viisi testaajaa. Käyttäjätestin tuloksia tukemaan tehtiin myös verkkomittauksia. Tutkimuksen tulokset osoittavat, että Pikapuhetta pidetään mukavana ja helppona. Tulokset osoittavat myös, että palveluiden liikuteltavuus on tärkeää, koska kukaan ei lopulta osallistunut testiin tietokonetta käyttäen. Viiveet, häviöt ja Pikapuhe-ohjelmien hankaluudet aiheuttavat yhä ongelmia. Myös mittauksissa todettiin viiveitä, mutta häviöitä ei tapahtunut. Vaikka Pikapuhe koettiinkin helpoksi, ei todellisia käyttötilanteita jokapäiväisestä elämästä löydetty kovinkaan paljon ja suurin osa testaajista käyttäisi mieluummin muita pikaviestimiä. Sen sijaan testin osallistujat keksivät useita erityistilanteita ja ammattiryhmiä, jotka voisivat hyötyä tällaisesta palvelusta.Push to Talk over Cellular (PoC) is an instant messaging type of new mobile service. It is possible to use PoC on one-to-one conversations and one-to-many conversations. The PoC service has not been as successful as predicted in Finland. In this thesis a multi-access PoC-system was implemented and user experience was collected. The system can be accessed both with a mobile phone PoC client and a PC PoC -client. 14 testers took part in the test, which lasted 2 months. During and after the test participants were asked to answer questionnaires. Another method was to observe a moving-situation in which five of the testers participated. Also network measurements were performed to analyse the user experience. The results of the survey show that users find PoC fun and quite easy to use. Results also show that mobility is very important, since no one actually took part in the test with a PC PoC -client. Delays, losses and some difficulties with PoC clients are still problematic. Measurements show similar delays, though they show no losses in network traffic. Even though PoC is considered easy, not so many actual use cases can be found in everyday life and the majority prefer other instant messaging. Instead the participants suggested many specific situations and occupational groups that could benefit from this type of service

Redes de nova geração e o serviço universal de telecomunicações em Portugal

Doutoramento em Engenharia EletrónicaThis thesis addresses the issue of Universal Service for telecommunications in the context of the access networks of next generation. This work aims to contribute to the redefinition of the concept of universal telecommunications service focusing primarily on extending it to broadband services as economic and social development factor and taking into account the degree of dependence that currently, modern societies have for the different communication and information services. Complementarily it also intended to meet some of the challenges set out in the European 2020 agenda. Universal Service is defined here as access to a telecommunications network (with obligations in terms of type and quality of service for the operator), by of all citizens at any country's geographical location, with uniform and accessible price. The approach adopted is the State as a mentor for social equity, respectful of the liberalized market dynamics but also knowledgeable of the requirements of modern telecommunications services and its relationship with the different technologies available. The possibility of subsidizing is assumed. The Universal Service´s provision is subject to open to all operators, which are assumed to possess other profitability businesses, than the Universal Service, using technologies similar to those prescribed for the respective Universal Service provision contest. Although the work has components of economic and financial analysis, the approach is the engineering point of view, looking for help to identify technical and organizational solutions which offer prospects for the dissemination and adoption of next generation network solutions. As a point of departure the work gives an overview on the state of the art access networks , trying to identify which of the differences between this reality and possible scenarios for next-generation network with potential access to the generality of the people . The case of the Portuguese reality will be given special attention, taking into account their specific characteristics in terms of geography, demography, economics and market dynamics. The main results of this work are: • Identification of possible scenarios for the evolution of existing networks, in particular in areas with deficit coverage. • Identification of possible operating models and business to the materialization of the above scenarios developed and its economic analysis in an attempt to determine the critical factors associated with sustainability and / or need for subsidies. • Contribution to the regulatory framework of new generation networks from the point of view of the constraints of technology and the specifics of the Universal Service.Esta tese aborda a questão do serviço universal de telecomunicações no contexto das redes de acesso de nova geração. Este trabalho pretende contribuir para a redefinição do conceito de Serviço Universal de Telecomunicações concentrando-se principalmente em estendê-lo a serviços de banda larga como factor de desenvolvimento económico e social e tendo em conta o grau de dependência que, actualmente, as sociedades modernas têm em relação aos diferentes serviços de comunicação e informação. De forma complementar pretende-se também ir ao encontro de alguns dos desafios enunciados na Agenda Europeia 2020. Serviço Universal é aqui definido como o acesso a uma rede de telecomunicações (com obrigações em termos de tipo e qualidade de serviço para o operador), por parte de todos os cidadãos, em qualquer localização geográfica do país, a preços uniformes e acessíveis. A perspectiva adoptada é a Estatal como mentor da equidade social, respeitador das dinâmicas de mercado liberalizado mas também conhecedor dos requisitos dos modernos serviços de telecomunicações e da sua relação com as diferentes tecnologias disponíveis. A possibilidade de subsidiação é assumida. A prestação de Serviço Universal é sujeita a concurso aberto a todos os operadores, que se assume possuírem outros negócios, que não apenas o Serviço Universal, com rentabilidade e usando tecnologias semelhantes às preconizadas para a respectiva prestação de Serviço Universal. Embora o trabalho desenvolvido tenha componentes de análise económico-financeira, a abordagem utilizada é a de engenharia, procurando contribuir para a identificação de soluções técnicas e organizacionais que possam oferecer perspectivas sustentáveis para a disseminação e adopção das soluções redes de nova geração. Como ponto de partida o trabalho apresenta uma visão geral sobre o estado da arte das redes de acesso, procurando identificar quais os diferenciais existentes entre essa realidade e a de possíveis cenários de rede de próxima geração com potencial de acesso para a generalidade dos cidadãos. O caso da realidade Portuguesa será objecto de uma atenção especial, tendo em consideração as suas especificidades em termos de geografia, demografia, economia e dinâmicas do mercado. Os principais resultados deste trabalho são os seguintes: • Identificação de possíveis cenários para a evolução das redes actuais, nomeadamente em áreas com deficit de cobertura de rede. • Identificação de possíveis modelos de operação e negócio para a materialização dos cenários acima desenvolvidos e respectiva análise económica, como tentativa de determinar os factores críticos associados à sua sustentabilidade e /ou necessidade de subsidiação. • Contributo para o quadro regulatório das Redes de Nova Geração sob o ponto de vista dos constrangimentos das tecnologias e das especificidades do Serviço Universal

A framework for determining the adoption of new services in the South African mobile telecommunications market

Abstract in English, Afrikaans and ZuluThe aim of this study was to determine the key factors which explain the adoption of mobile data services in South Africa and incorporate them into an explanatory framework that can be used to indicate whether a new mobile data service that is introduced into the South African Mobile Market will be successful. Additionally, it shows that the current usage of mobile data services in South Africa supports the framework. The research used a design based on a mixed methods methodology. The research was conducted using a literature survey and two research phases. The literature survey was an extensive review of communication technology adoption frameworks and all the possible factors of adoption. This literature survey was also used to develop the discussion document which was used as the guidelines for the Phase 1 interviews. The interviews were with experts in the telecommunications market in South Africa and were used to determine the key drivers of adoption and possible moderating factors of mobile data services. From those interviews a preliminary model was proposed. Phase 2 was a market survey which tested the framework and moderating factors in different metropolitan areas as well as examined the current usage of mobile data services. The statistical analysis used in determining the framework incorporated Descriptive Statistics, Factor Analysis, using Principal Axis Factoring, and Structural Equation Modelling. The framework, which was based on the Technology Acceptance Model, introduced two new constructs. The first new construct was the Mobile Service Providers Marketing Tactics and the second was Social Pressure and Aspirational Value. The two constructs combined can be used to explain why mobile service providers with low cost strategies are not successful. Demographic factors such as Age were found to influence the adoption as well as Socio-economic factors such as Income. Personal factors such as Technical Knowledge, Ability and Skills and Attitude towards Technology were also found to influence adoption. Geographical location was found to be the most important moderating factor. The current mobile data usage supported the framework. The results of data usage highlighted the fact that nearly 50% of the study’s participants spent over 4 hours per day interacting with their mobile devices and that the participants from Gauteng spent more than 2½ times on mobile services than those in the other metropolitan municipalities of Cape Town and eThekwiniDie doel van hierdie studie was om die sleutelfaktore te bepaal wat die aanneming van selfoondatadienste in Suid-Afrika verklaar, en hulle te verenig in ʼn raamwerk waarmee aangetoon kan word of ʼn nuwe selfoondatadiens die Suid-Afrikaanse selfoondatamark suksesvol sal betree. Afgesien hiervan dui hierdie studie aan dat die huidige gebruik van selfoondatadienste in Suid-Afrika die geldigheid van die voorgestelde raamwerk bevestig. ʼn Mengsel van metodes is in die navorsing toegepas. Die navorsing het uit ʼn literatuuroorsig en twee navorsingsfases bestaan. Die literatuuroorsig het ʼn deurtastende oorsig van die raamwerke vir die aanneming van kommunikasietegnologie en alle moontlike faktore daarvoor behels. Uit die literatuuroorsig is die besprekingsdokument saamgestel wat as riglyn gedien het vir die onderhoude in fase 1 van die navorsing. Onderhoude is met kundiges uit die Suid-Afrikaanse telekommunikasiebedryf gevoer om die belangrikste dryfvere vir aanneming en moontlike remfaktore ten opsigte van selfoondatadienste te bepaal. ʼn Voorlopige model is op grond van die onderhoude aangebied. Fase 2 het ʼn markopname behels waarin die raamwerk en remfaktore in verskeie metropolitaanse gebiede getoets en die huidige gebruik van selfoondatadienste ondersoek is. Die statistiese analise waarop die raamwerk berus, het bestaan uit beskrywende statistiek, faktorontleding met behulp van hoofasfaktorering, en struktuurvergelykingsmodellering. Twee nuwe konstrukte het uit die raamwerk wat op die tegnologieaanvaardingsmodel gegrond was, gespruit. Die eerste was selfoondiensverskaffers se bemarkingstrategieë en die tweede sosiale druk en aspirerende waarde. Saam verklaar die twee konstrukte waarom selfoondiensverskaffers wat laekostestrategieë volg, misluk. Daar is bevind dat demografiese faktore soos ouderdom, en sosiaal-ekonomiese faktore soos inkomste, aanneming beïnvloed. Volgens die bevindings word aanneming eweneens bepaal deur persoonlike faktore soos tegniese kennis, vermoë en vaardighede asook houding jeens tegnologie. Daar is bevind dat geografiese ligging die belangrikste remfaktor is. Die huidige selfoondatagebruik bevestig die geldigheid van die raamwerk. Die uitslag van datagebruik benadruk die feit dat byna 50% van die deelnemers aan die studie langer as vier uur per dag met hulle selfone doenig is, en dat deelnemers in Gauteng twee en half keer meer as deelnemers in die metropolitaanse munisipaliteite van Kaapstad en eThekwini aan selfoondienste bestee.Inhloso yalolu cwaningo bekuwukuthola izinto ezibalulekile ezichaza ukwamukelwa kwezinsiza zamadatha amaselula eNingizimu Afrika nokuzifaka ohlakeni oluchazayo olungasetshenziswa ukukhombisa ukuthi ngabe insiza entsha yedatha ethulwe emakethe yamaselula eNingizimu Afrika izophumelela. Ngaphezu kwalokho, kukhombisa ukuthi ukusetshenziswa kwamanje kwezinsiza zedatha yamaselula eNingizimu Afrika kuyalusekela uhlaka. Ucwaningo lusebenzise umklamu osuselwe ezindleleni zokwenza ezixubile. Ucwaningo lwenziwe kusetshenziswa ucwaningo lwezincwadi kanye nezigaba ezimbili zocwaningo. Ucwaningo lwezincwadi belungukubuyekezwa okubanzi kokwamukela kwenzinhlaka zobuchwepheshe kwezokuxhumana kanye nazo zonke izici ezingenzeka ukuthi zamukelwe. Lolu cwaningo lwezincwadi lusetshenzisiwe futhi ukuthuthukisa umqulu wezingxoxo osetshenziswe njengezinkombandlela zokuxoxisana nabantu besigaba 1. Izingxoxo ebezinazo bezingochwepheshe emakethe yezokuxhumana eNingizimu Afrika futhi zasetshenziselwa ukuthola izidingongqangi zokwamukelwa kanye nezici zokulingisanisa kwezinsiza zamadatha amaselula. Kulezo zingxoxo, kuphakanyiswe isifaniselo sokuqala. Isigaba 2 bekungukucwaningo lwezimakethe oluhlola uhlaka kanye nezici zokulinganisa ezindaweni ezahlukahlukene zedolobha kanye nokuhlola ukusetshenziswa kwamanje kwezinsiza zedatha yamaselula. Ukuhlaziywa kwezibalo okusetshenzisiwe ekunqumeni uhlaka lufake izibalo ezichazayo, ukuhlaziya izakhi, kusetshenziswa izisekelo eziyinhloko zokuphamba, kanye nesifaniselo sokulinganisa esihlelekile. Uhlaka, olwalususelwa kusifaniselo sokwamukela ubuchwepheshe, lwethule izakhiwo ezimbili ezintsha. Isakhiwo esisha sokuqala kwakungamacebo wokukhangisa wabahlinzeki bezinsiza zamaselula futhi owesibili kwakuyingcindezi yomphakathi nenani lesifiso. Lezi zakhiwo zombili ezihlanganisiwe zingasetshenziswa ukuchaza ukuthi kungani abahlinzeki bezinsizakalo zamaselula abanamasu ezindleko eziphansi bengaphumeleli. Izici ezithinta abantu ezinjengobudala zitholakele ukuthonya ukwamukelwa kanye nezici zezomnotho nezenhlalo ezifana nomholo. Izici ezithinta umuntu ngqo ezifana nolwazi lwezobuchwepheshe, ukwazi ukwenza kanye namakhono, nesimo sengqondo maqondana nezobuchwepheshe zatholakala zithonya ukwamukelwa. Indawo yendawo yatholakala njengesici sokulinganisa esibaluleke kakhulu. Ukusetshenziswa kwedatha yeselula yamanje kusekele uhlaka. Imiphumela yokusetshenziswa kwedatha igcizelele iqiniso lokuthi bacishe babe ngama-50% ababambe iqhaza kulolu cwaningo bachithe isikhathi esingaphezu kwamahora amane ngosuku bexhumana nemishini yabo yamaselula nokuthi ababambiqhaza abavela eGauteng bachithe izikhathi ezingaphezu kwezingu-2½ kuzinsiza zamaselula kunalabo bakwamanye amadolobha amakhulu aseKapa naseThekwini.Business ManagementD.B.L

Quality of service differentiation for multimedia delivery in wireless LANs

Delivering multimedia content to heterogeneous devices over a variable networking environment while maintaining high quality levels involves many technical challenges. The research reported in this thesis presents a solution for Quality of Service (QoS)-based service differentiation when delivering multimedia content over the wireless LANs. This thesis has three major contributions outlined below: 1. A Model-based Bandwidth Estimation algorithm (MBE), which estimates the available bandwidth based on novel TCP and UDP throughput models over IEEE 802.11 WLANs. MBE has been modelled, implemented, and tested through simulations and real life testing. In comparison with other bandwidth estimation techniques, MBE shows better performance in terms of error rate, overhead, and loss. 2. An intelligent Prioritized Adaptive Scheme (iPAS), which provides QoS service differentiation for multimedia delivery in wireless networks. iPAS assigns dynamic priorities to various streams and determines their bandwidth share by employing a probabilistic approach-which makes use of stereotypes. The total bandwidth to be allocated is estimated using MBE. The priority level of individual stream is variable and dependent on stream-related characteristics and delivery QoS parameters. iPAS can be deployed seamlessly over the original IEEE 802.11 protocols and can be included in the IEEE 802.21 framework in order to optimize the control signal communication. iPAS has been modelled, implemented, and evaluated via simulations. The results demonstrate that iPAS achieves better performance than the equal channel access mechanism over IEEE 802.11 DCF and a service differentiation scheme on top of IEEE 802.11e EDCA, in terms of fairness, throughput, delay, loss, and estimated PSNR. Additionally, both objective and subjective video quality assessment have been performed using a prototype system. 3. A QoS-based Downlink/Uplink Fairness Scheme, which uses the stereotypes-based structure to balance the QoS parameters (i.e. throughput, delay, and loss) between downlink and uplink VoIP traffic. The proposed scheme has been modelled and tested through simulations. The results show that, in comparison with other downlink/uplink fairness-oriented solutions, the proposed scheme performs better in terms of VoIP capacity and fairness level between downlink and uplink traffic