Self-organization, cooperation and control distribution in wide and local area networks
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.
School:Kungliga Tekniska högskolan
Source Type:Master's Thesis
Keywords:TECHNOLOGY; Information technology; Telecommunication
Date of Publication:01/01/2007