Although radio repeaters and wireless routers are commonly used, relaying techniques have received a lot of attention in academic publications the last decade. Most of the techniques proposed in the literature are based on relaying terminals. For instance groups of mobile terminals cooperate so as to jointly communicate with an access point, or to another group of mobiles in an (infrastructure-less) mobile ad-hoc network MANET. However, it has also been suggested that these techniques can be applied to hybrid cellular-relaying architecture with fixed relays and that this would reduce the infrastructure costs. The literature shows that the coverage or capacity of a cellular network is enhanced when using relays. A common assumption in these studies is that relays are very low cost, but little attention has been given to how cheap these relays need to be in order for the technical enhancements to translate into an economic gain. It is not obvious that the techniques proposed for mobile relaying are economically feasible when applied to fixed relays. This thesis examines the conditions under which large scale usage of fixed relays leads to lower infrastructure cost than in a purely cellular architecture, how large the benefits of these new techniques are, compared with existing repeater/router techniques, and how sensitive the results are to traditional network design parameters. The analysis is done by means of several study cases in which coverage should be provided for broadband services by building a network from scratch. The results are expressed in terms of how cheap a relay must be with respect to a base station's cost so that the hybrid infrastructure provides the desired service at a lower cost. If in practice this relative relay cost is much lower, then high economic gains are expected. None of the study cases considered yield substantial cost savings when using fixed relays on a large scale. When access points are placed as high as in a cellular network, the hybrid system is feasible only if the total relay cost is 3-20% of the total base station cost. When unplanned relay deployment is used, the impact of the antenna height and/or gain on the results is much greater than the particular type of amplify-and-forward relaying scheme. Planned deployment of a few relays should be used unless the cost of planning is 1-2 times larger than all the other relay costs. A proper trade-off between route-length and how tight the radio channel can be reused is essential for the feasibility of the hybrid system. The results confirm that the planned usage of few relays together with macro-like base stations is an efficient way of providing coverage. Analysis of other scenarios, such as the use of pico base stations for coverage, is left for further studies. / QC 20101125

To support the future requirements on wireless systems in an affordable manner it is commonly believed that multiple radio access technologies have to be combined. These technologies can be deployed by a single operator or, even, be managed by different competing operators. In order to cope with the increased complexity of such a multifaced wireless environment it has been argued that a transfer of Radio Resource Management (RRM) functionalities towards the network edges (access ports and, ultimately, user terminals) may be beneficial. In addition to detecting varying system conditions in a faster manner this would also allow a more responsive service adaptation. In this thesis we evaluate a set of self-organizing regimes, all with the purpose of supporting the distribution of control at the edge node. Particular emphasis is put on the design of a mechanism for dynamically establishing cooperation between different network entities whether these are access ports or user terminals. Terminal cooperation by means of multihopping is considered in the context of service provision in cellular access systems. Previously the opportunity cost associated with sharing own bandwidth, and energy loss have been seen as a major obstacle for relaying other users’ traffic. To mitigate the effects of this selfish behavior the concept of resource delegation is introduced and evaluated in combination with a rewarding scheme designed for compensating the energy losses induced by forwarding. The results show that our proposed schemes not only are capable of fostering significant cooperation among users, but also to create a simultaneous improvement in user utility, data rates as well as in operator revenues. Opening up networks of user-deployed Access Points (APs) for service provision is considered a means to radically lower the cost of future wireless services. However, since these networks are deployed in an uncoordinated manner, only discontinuous coverage will be provided. The question of how dense these networks need to be, to deliver acceptable user perception, is investigated in this thesis for a set of archetypical services. The results show that already at moderate AP densities the investigated services can be provided with sufficient quality. Epidemic exchange of popular content and inter-AP cooperation are also shown to further decrease the required infrastructure density and improve the APs’ utilization respectively. As last contribution, “Word-of-Mouth”, a distributed reputation-based scheme, is investigated in the context of access selection in multi-operator environments. By exchanging information concerning the Quality of Service (QoS) associated with the different networks, terminal agents can collectively reveal the capabilities of individual networks. For a vertical handover scenario we show that our proposed scheme can reward access providers capable of ensuring some degrees of QoS. By introducing a model for collusion, between low performing APs and terminal agents, we show that our proposed scheme is also robust to the dissemination of false information. / QC 20101112

This study postulates that the current incumbents in the SA mobile telecommunications industry are still relying on old working mobile technologies even though new types are emerging within the industry. The telecommunications industry is undergoing radical changes of its own; some examples include global liberalization of trade and investment in telecommunications, as well as national deregulation and privatization. Thus, SA telecommunications businesses are facing a double dilemma: while the telecommunications technology and industry are being rapidly redefined, the markets are being opened to local and global competition.

This study postulates that the current incumbents in the SA mobile telecommunications industry are still relying on old working mobile technologies even though new types are emerging within the industry. The telecommunications industry is undergoing radical changes of its own; some examples include global liberalization of trade and investment in telecommunications, as well as national deregulation and privatization. Thus, SA telecommunications businesses are facing a double dilemma: while the telecommunications technology and industry are being rapidly redefined, the markets are being opened to local and global competition.

Abstract The programme of the DoC-WILs is an init iat ive of the Department of Communicat ions in collaborat ion with Telkom, established through the Human Resources Fund to enable human resources development at historically disadvantaged learning institut ions. The Telecommunicat ions Act No 103 of 1996 establishes a Human Resources Fund to promote the provision of adequately skilled human resources at all levels of the telecommunicat ions sector in numbers suf f icient for the telecommunicat ions needs of the count ry. The DoC-WILs emphasise skills development through the use of ICTs in areas such as network management , creat ing Web sites, use of E-mail and the World Wide Web, mult imedia applicat ions and Int ranet development . It is however not known under what contextual circumstances this kind of ICT-usage will lead to interact ive learning benef its and how the DoC-WILs should go about achieving them. This art icle therefore at tempts to shed some light on the condit ions under which ICT usage could impact on educat ional outcomes desired by the DoCWILs and on how these DoC-WILs could best go about taking appropriate act ions to improve the possibility of achieving desired interact ive learning benef its. It is argue that the ability of the DoC-WILs to successfully achieve desired benef its is crucially dependent on contextual conditions, policies or processes that apply to the DoC-WILs or their users. This is in line with the social shaping of technology approach that local circumstances surrounding the deployment of ICTs in different sectors of society are more important in shaping the consequence of ICTs than technological variable.

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