D2D Coded Caching from Two Classes of Optimal DPDAs Using Cross Resolvable Designs

Coded caching in a wireless device-to-device (D2D) network was first studied by Ji et al. in [4] (referred to as the JCM scheme). Wang et al. in [7] proposed the D2D placement delivery array (DPDA) that characterizes coded caching in a D2D network and derived a lower bound on the transmission load of a DPDA. Only the JCM scheme achieves this bound but requires a subpacketization level that grows exponentially with the number of users. This paper proposes two new classes of DPDA constructions that give low subpacketization level D2D schemes using cross resolvable designs. The first class of constructed DPDA achieves the known lower bound on the transmission load of DPDA while requiring a subpacketization level lesser than that of the JCM scheme. A new lower bound on the transmission load of a DPDA is proposed and shows that the second class of constructed DPDA achieves this lower bound.