Context-based Resource Management and Architectures for Future Wide and Local Area Wireless Networks

Sammanfattning: In the last few years we have been witnessing the beginning of a revolution in the world of wireless communication. The recent launch of advanced smartphones in the mobile market has been welcomed by mobile operators as an opportunity to finally fulfill the promises of 3G and increase the uptake of mobile services. Driven by unprecedented user experience and flat rate pricing, the success of novel mobile platforms for accessing multimedia content and applications has gone far beyond the most optimistic of expectations. Data-hungry services are currently creating significant capacity limitations in many networks, and projections on future content consumption anticipate that with the next generation of mobile devices the stress on cellular infrastructures will increase. Rolling-out additional capacity is not the most profitable of solutions given the current cost structure of mobile infrastructures. Instead, a significant cost reduction can be achieved by revolutionizing the current content provision paradigm. Accordingly, this thesis proposes solutions for making future services and infrastructures more affordable. From an operator perspective, terminal-to-terminal information forwarding has the potential to increase both coverage and capacity, however it introduces opportunity costs and energy losses at the user side. Resource delegation, together with an energy reimbursement scheme, is presented in this thesis to induce user cooperation. The results show that this approach is successful in fostering significant cooperation among users and can create a simultaneous improvement in user utility, data rates and operator revenues. Opening up for public access privately deployed WLANs might radically lower the cost of wireless services. However, since these networks are deployed in an uncoordinated manner, only discontinuous coverage can be provided. To hide the sparsity of the infrastructure to the end-user perception we propose the adoption of opportunistic schemes for content pre-fetching. Results show that already with moderate AP densities a set of archetypical services, including web-browsing, can be provided with sufficient user perceived quality. Epidemic exchange of popular content, and inter-AP cooperation are also shown to further decrease the required AP density. Moreover, to support informed access selection decisions when performing vertical handovers to WLANs, we propose “Word-of-Mouth”, a reputation-based scheme for revealing the QoS of different networks. By epidemically exchanging grades on their experienced service quality, we show that terminal agents can collectively improve their decision making, avoiding selecting networks not meeting the required QoS. Context-based content delivery is presented in this thesis as means to improve the utilization of wireless resources in cellular systems. Since networks are typically dimensioned for peak hour traffic, the BSs are underutilized for significant portions of the day. By adopting context-based architectures, capable of opportunistically utilizing the instantaneous excess of resources for content pre-fetching, we show that a significant amount of additional traffic can be served in already existing networks. The gains introduced by this content provision paradigm over the current “on-demand” solutions are further expressed in terms of lower requirements on BS density, more users in the system and larger files served while reaching the same level of user experience.