Cost-effective hybrid satellite-terrestrial networks : Optimal beamforming with nonlinear PA and large-scale CSIT

This thesis explores a new form of urban public place—multifunctional venues called ‘pay-per-minute cafes’, ‘public living rooms’, or ‘anti-cafes’. Charged by the minute and provided with free wifi and access to kitchen facilities, visitors of such spaces are entitled to use them however they like, as they are designed to accommodate various social, cultural, home-from-home and work activities. The first venue of this kind, Ziferblat, opened in 2011 in Moscow as a social experiment seeking to build ‘social media in real life’, turn customers into participants and overcome the limitations of the functionalist urban planning separating home, work and leisure from each other. In the next couple of years, Ziferblat’s look-alikes have spread overseas to Europe, Asia and North America; meanwhile, Ziferblat itself has developed into an international franchise with 18 branches, five of which are located in the UK. Using this phenomenon as a lens on two emerging urban trends—the post-functionalist city and the post-digital city—this thesis investigates the ‘who’, ‘why’, and ‘how’ of placemaking in the context of current debates on sociability, diversity and social inclusion in the urban public space, participatory culture and sharing economy, and neoliberal urban policy. This critical case study, drawing on large-scale media analysis, 48 qualitative interviews and over 160 hours of ethnography conducted in four Ziferblat branches in Moscow, London and Manchester, employs an interdisciplinary theoretical framework, combining urban sociology, human geography, cultural anthropology, media studies, and consumer and service research to examine the intricate connections and contradictions between the social and the spatial, the global and the local, the social and the commercial, the public and the private, the physical and the digital. The research findings are of potential interest to academics, practitioners, social activists, urban planners and policymakers dealing with the issues of placemaking and community building in the city. In hybrid satellite-terrestrial networks (HSTNs), spectrum sharing is crucial to alleviate the “spectrum scarcity” problem. Therein, the transmit beams should be carefully designed to mitigate the inter-satellite-terrestrial interference. Different from previous studies, this work considers the impact of both nonlinear power amplifier (PA) and large-scale channel state information at the transmitter (CSIT) on beamforming. These phenomena are usually inevitable in a cost-effective practical HSTN. Based on the Saleh model of PA nonlinearity and the large-scale multi-beam satellite channel parameters, we formulate a beamforming optimization problem to maximize the achievable rate of the satellite system while ensuring that the inter-satelliteterrestrial interference is below a given threshold. The optimal amplitude and phase of desired beams are derived in a decoupled manner. Simulation results demonstrate the superiority of the proposed beamforming scheme.