Two Methods Of Constructing Centralized Coded Caching Schemes

With the rapid development of mobile terminals,the data transmissions mainly in the form of video,in the wireless network increase significantly.In addition,for communication systems,the high temporal variability of network traffic results in congestion during peak traffic times and insufficient utility of communication resources during off-peak traffic times.The Caching technology is a solution for the mismatch problem between data transmissions and communication resources.It reduces the congestion during peak traffic times by means of utilizing the communication resources during off-peak traffic times.Focusing on centralized coded caching model,a special structure called placement delivery array(PDA)is able to sketch two phases of coded caching schemes.In this paper,focusing on centralized coded caching model,we will construct PDAs by means of two methods: concatenating constructions and direct construction.Aiming at the concatenating constructions method,we propose two concatenation schemes for PDA.Especially,the second scheme holds the advantage of no waste of cache resources.Then we obtain two new PDAs which correspond to coded caching schemes with full advantages compared to a previously existing scheme.Aiming at the direct construction method,we propose a framework for constructing PDAs via Hamming distance and propose two new classes of PDAs.The performance comparison analysis illustrates the realized new coded caching schemes have full advantages compared to several previously known schemes.Differing from most previous studies,the framework for constructing PDAs in his paper is aimed at schemes with subpacketizations increasing linearly with the number of users.Under this framework,constructing PDAs has relatively flexible parameters.Besides,in this paper we consider designing PDAs according to the latest realization strategy except the primary realization strategy from PDAs to coded caching schemes.