Taming Subpacketization without Sacrificing Communication: A Packet Type-based Framework for D2D Coded Caching

2026-02-12

AI Summary

This work addresses the challenge of excessive subpacketization that hinders the practical deployment of device-to-device (D2D) coded caching in finite-length scenarios. To mitigate this issue, the paper proposes a packet-type (PT)-based design framework that introduces asymmetry through user grouping and systematically exploits this asymmetry during both cache placement and multicast delivery to reduce subpacketization. The key innovation lies in identifying and realizing two types of subpacketization reduction gains—subfile-saving gain and further-splitting-saving gain—thereby significantly lowering complexity while preserving optimal communication rates. The proposed scheme jointly optimizes user grouping, asymmetric file splitting, and multicast scheduling via integer linear programming (ILP). Compared to the Ji–Caire–Molisch (JCM) scheme and other state-of-the-art approaches, it achieves substantially lower subpacketization levels without compromising rate optimality.

Technology Category

• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Search and Optimization: Distributed Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Security and Privacy: Large-scale security measurements
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications

Abstract

Finite-length analysis is critical for bringing coded caching closer to practical deployment. In this work, we study the design of communication rate-optimal device-to-device (D2D) coded caching schemes with minimal subpacketization levels, a key bottleneck in finite-length settings. We present a novel \tit{packet type-based} (PT) design framework that (i) strategically introduces \tit{asymmetry} into file splitting through user grouping, and (ii) systematically exploits such asymmetry in both cache placement and multicast delivery to create subpacketization reduction opportunities. In particular, the induced asymmetry gives rise to two fundamental forms of subpacketization reduction gains: the \emph{subfile saving gain}, achieved by eliminating certain types of subfiles through careful user grouping and transmitter selection, and the \emph{further splitting saving gain}, attained by reducing the splitting granularity for the remaining subfiles. The combined effect of these two reduction gains yields an overall subpacketization improvement over the original Ji-Caire-Molisch (JCM) caching scheme~\cite{ji2016fundamental}, as well as various state-of-the-art schemes, while preserving optimal communication rates. Under the PT framework, we formulate the caching scheme design as an integer linear program (ILP), where each feasible solution corresponds to a valid rate-optimal D2D coded caching scheme with potentially reduced subpacketization relative to the JCM baseline.

Problem

• coded caching
• subpacketization
• device-to-device (D2D)
• communication rate
• finite-length

Innovation

• packet type-based framework
• subpacketization reduction
• asymmetric user grouping
• D2D coded caching
• integer linear programming