Research On Coded Caching In One-Dimensional Nonuniform Coverage Multiple Access Network And Two-Dimensional Caching-Aided Ultra-Dense Network

With the popularity of internet-enabled smart mobile devices,mobile network data has experienced unprecedented growth due to the rapid development and promotion of applications such as ultra-high-definition video,multimedia and the Internet of Things.The transmission pressure of traffic in wireless networks has sharply increased,forcing people to develop new technologies to meet the growing demand for wireless data communication.Maddah-Ali and others combined network coding and caching technology to propose a coded caching technology that transfers the transmission pressure of peak periods to off-peak periods,achieving optimal transmission load for the centralized coded caching network model.Subsequently,Hanchem and others applied coded caching technology to wireless edge network models,utilizing the large storage capacity and fast access speed of wireless edge nodes to further improve spatial and spectrum efficiency and reduce network communication costs.However,the above research on coded caching did not consider some more complex and practical application scenarios.Firstly,the case of non-uniform coverage scenarios for wireless edge nodes was not considered.Secondly,the previous work assumed that each user accessed the same number of wireless edge nodes,ignoring the fact that the number of nodes accessed by users may vary depending on their geographical location.In response to the above shortcomings,this paper expands the application scenarios of the centralized coded caching scheme,and designs new centralized coded caching schemes for one-dimensional nonuniform coverage multiple access network and two-dimensional caching-aided ultra-dense network,the main works are as follows:Firstly,this paper investigates the coded caching problem in one-dimensional nonuniform coverage multiple access network model.The model includes a server with N files,K cache-less users,and K cache nodes with the cache size of M files.The cache nodes are divided into strong and weak cache nodes,the strong cache nodes located in the middle,serving a larger area than the weak cache nodes.Inspired by the partition scheme,this paper designs a reliable coded caching scheme with lower transmission load for this model.Secondly,this paper focuses on the coded caching problem in two-dimensional cache-assisted ultra-dense network model.In a two-dimensional cache-assisted ultra-dense network,there is a server containing N files,K₁ K ₂ cache nodes arranged in a matrix with a capacity of M files,and U cache-less users randomly distributed around the cache nodes.The server is connected to the users through an error-free shared link,and the service radius of each cache node is r.Users within the cache node’s service radius can retrieve all cached content from the cache node at no cost.Based on the centralized coded caching proposed by Ali et al.,this paper designs an order optimal coded caching scheme A for the two-dimensional caching-aided ultra-dense network model to satisfy all possible user’s requests and minimize the transmission load.Furthermore,by using the maximum distance separable coded technology to improve scheme A,a coded caching scheme B with a transmission load lower than scheme A can be obtained.