D2D-assisted caching on truncated Zipf distribution

\u3cp\u3eIn this paper, device-to-device (D2D)-assisted caching is considered to offload traffic from the capacity-stringent backhaul networks to the proximity of users. First, a three-layer hierarchical content provision model is established, where a requested content can be fetched from the local cache directly, from the cache of a proximal device through D2D communications, or from the serving base station through backhaul transmissions. Then, for a general multi-unit-cache equipped at each device, we propose independent content placement in each cache unit and correlated content placement in each cache unit without repetition, based on which the problem of maximizing the edge cache hit ratio is formulated. Instead of optimizing the caching probability for all contents in the library, we propose a parameter-based caching framework based on a truncated Zipf distribution, where only the position of truncation and the Zipf exponent are involved. For jointly determining the optimal values of the two parameters, a genetic algorithm and a two-step search algorithm are designed. The simulation results demonstrate that the correlated content placement outperforms its independent counterpart, and significant performance gains can be achieved by the proposed parameter-based caching framework in comparison with most existing approaches.\u3c/p\u3

Urban Informatics

This open access book is the first to systematically introduce the principles of urban informatics and its application to every aspect of the city that involves its functioning, control, management, and future planning. It introduces new models and tools being developed to understand and implement these technologies that enable cities to function more efficiently – to become ‘smart’ and ‘sustainable’. The smart city has quickly emerged as computers have become ever smaller to the point where they can be embedded into the very fabric of the city, as well as being central to new ways in which the population can communicate and act. When cities are wired in this way, they have the potential to become sentient and responsive, generating massive streams of ‘big’ data in real time as well as providing immense opportunities for extracting new forms of urban data through crowdsourcing. This book offers a comprehensive review of the methods that form the core of urban informatics from various kinds of urban remote sensing to new approaches to machine learning and statistical modelling. It provides a detailed technical introduction to the wide array of tools information scientists need to develop the key urban analytics that are fundamental to learning about the smart city, and it outlines ways in which these tools can be used to inform design and policy so that cities can become more efficient with a greater concern for environment and equity

Urban Informatics

This open access book is the first to systematically introduce the principles of urban informatics and its application to every aspect of the city that involves its functioning, control, management, and future planning. It introduces new models and tools being developed to understand and implement these technologies that enable cities to function more efficiently – to become ‘smart’ and ‘sustainable’. The smart city has quickly emerged as computers have become ever smaller to the point where they can be embedded into the very fabric of the city, as well as being central to new ways in which the population can communicate and act. When cities are wired in this way, they have the potential to become sentient and responsive, generating massive streams of ‘big’ data in real time as well as providing immense opportunities for extracting new forms of urban data through crowdsourcing. This book offers a comprehensive review of the methods that form the core of urban informatics from various kinds of urban remote sensing to new approaches to machine learning and statistical modelling. It provides a detailed technical introduction to the wide array of tools information scientists need to develop the key urban analytics that are fundamental to learning about the smart city, and it outlines ways in which these tools can be used to inform design and policy so that cities can become more efficient with a greater concern for environment and equity