A Direct Construction Of Coded Caching Schemes For Combination Networks

With the continuous advancement of communication technology,the utilization ratio of mobile Internet is increasing,and wireless traffic services are greatly enhanced.When the communication system is during the peak-traffic times,the transmission pressure of the network increases sharply,which leads to data transmission congestion;on the contrary,during the off-traffic times,there is insufficient utilization of communication resources.Cache technology began to appear,that is,first put a part of the data into the user's storage device during the off-traffic times of transmission,so as to reduce the transmission data during the peak-traffic times of transmission.This technique is gradually applied to different network models.This article discusses related issues for the combination networks and the asymmetric combination networks.As we all know,there is a tradeoff between the transmission rate and the packetization .When designing the scheme,we need to reduce the packetization as much as possible while ensuring the transmission rate.For the combination networks,different from the way that other authors directly design a suitable coded caching scheme,we obtain a new coded caching scheme by directly constructing Combinatorial Placement Delivery Array(CPDA).This article first proposes a new algorithm suitable for CPDA,which changes the previous design of randomly selecting a repeater to transmit coded information,and then sets a piece of coded information which can be composed of the way in which multiple relay distributes the transmission.In our discussion,two CPDAs are constructed,and at the expense of a small amount of transmission rate,the packetization es reduced exponentially.For the asymmetric combination networks,due to the different number of users connected to the relay,CPDA is not used when designing the coded caching scheme,but after grouping the users,priority is given to the one with a larger number of connected users,then meet the needs of the remaining users.Such a scheme design does not use the Maximum Distance Separable Codes(MDS)to reduce the complexity of the scheme,while ensuring the transmission rate,reducing the packetization to a certain extent.At the same time,the scheme in this article is suitable for different memory size of the users.