Asymmetric Stream Allocation and Linear Decodability in MIMO Coded Caching
This work addresses a specific bottleneck in MIMO coded caching for network communication systems, offering an incremental improvement over prior symmetric-constrained designs.
The paper tackles the problem of enabling practical linear receivers in MIMO coded caching systems by addressing the limitation of symmetric stream allocations, proposing a framework that allows asymmetric allocation while ensuring linear decodability, which expands the feasibility region of achievable Degrees of Freedom.
Coded caching (CC) can transform cache memory at network devices into an active communication resource. Prior studies have shown that CC can significantly enhance the achievable Degrees of Freedom (DoF) in multi-input multi-output (MIMO) systems. To fully exploit MIMO-CC gains across all SNR regimes and enable practical linear receivers, flexible scheduling is required. Existing DoF analysis, scheduling, and linear receiver design, however, largely assume symmetric stream allocations across users. This paper extends the authors' recent work on DoF and linear decodability analysis for MIMO-CC systems by deriving a simple criterion, based on per-user stream allocation, that guarantees linear decodability for both symmetric and non-symmetric bit-level CC schemes. Building on this, we propose a heuristic MIMO-CC delivery and scheduling framework that enables asymmetric stream allocation while adhering to linear decodability, thereby expanding the feasibility region of achievable DoF compared to symmetric-constrained designs.