D2D Coded Caching Schemes for Multiaccess Networks with Combinatorial Access Topology
Rashid Ummer N. T., B. Sundar Rajan
TL;DR
The paper develops combinatorial-design-based multiaccess D2D coded caching (MADCC) schemes that extend prior cyclic topologies by leveraging $t$-designs and $t$-GDDs to define access topologies. It constructs placement and delivery arrays (DPDA-like) and derives achievable memory-load tradeoffs, achieving lower subpacketization or favorable load under fixed cache budgets. The work also shows how MADCC schemes yield new D2D schemes for the original network and compares their performance to existing WCCWC and derived CWEC schemes, highlighting design-topology-driven gains and scalability. Practical directions include decentralization, flexible topologies, and handling nonuniform popularities and selfish nodes.
Abstract
This paper considers wireless device-to-device (D2D) coded caching in a multiaccess network, where the users communicate with each other and each user can access multiple cache nodes. Access topologies derived from two combinatorial designs known as the $t$-design and $t$-group divisible design ($t$-GDD), referred to as the $t$-design and $t$-GDD topologies respectively, which subsume a few other known topologies, have been studied for the multiaccess coded caching (MACC) network by Cheng \textit{et al.} in \cite{MACC_des}. These access topologies are extended to a multiaccess D2D coded caching (MADCC) network and novel MADCC schemes are proposed. MADCC network has been studied so far only for the cyclic wrap-around topology. Apart from the proposed novel MADCC schemes, MADCC schemes are also derived from the existing MACC schemes in \cite{MACC_des}. To compare the performance of different MADCC schemes, the metrics of load per user and subpacketization level are used while keeping the number of caches and cache memory size same. The proposed MADCC scheme with $t$-design topology performs better in terms of subpacketization level while achieving the same load per user compared to the MADCC scheme derived from the MACC scheme with $t$-design topology in \cite{MACC_des}. The proposed MADCC scheme with $t$-GDD topology performs better in terms of load per user while achieving the same subpacketization level compared to the MADCC scheme derived from the MACC scheme with $t$-GDD topology in \cite{MACC_des} in some cases. Compared to the existing MADCC scheme with cyclic wrap-around topology, the proposed MADCC scheme with $t$-design topology performs better in terms of load per user, and the proposed MADCC scheme with $t$-GDD topology performs better in terms of subpacketization level at the expense of an increase in load per user.