Design of Coded Caching Schemes through Proper Orthogonal Arrays

Abstract

Coded caching is an effective technique to utilize multicasting opportunities to reduce the data transmission load in cached networks. In such a scheme, each file in the data center or library is usually divided into a number of packets to pursue a low broadcasting rate based on the designed placements at each user’s cache. However, the implementation complexity of this scheme increases with the number of packets. It is crucial to design a scheme with a small subpacketization level, while maintaining a relatively low transmission rate. Recently, a combinatorial structure called placement delivery array (PDA) was proposed as an effective tool to design coded caching schemes with a low subpacketization level. This paper proposes a novel PDA construction by selecting proper orthogonal arrays (POAs). It generalizes the existing construction, making it suitable to the scenario with a more flexible memory size. Based on the proposed PDA construction, a new coded caching scheme with the coded placement is further proposed. It is shown that the proposed schemes can yield a lower subpacketization level or transmission rate over the benchmark schemes.