Wireless Multihop Device-to-Device Caching Networks

Abstract

We consider a wireless device-to-device (D2D) network where $n$ nodes are uniformly distributed at random over the network area. We let each node with storage capacity $M$ cache files from a library of size $m\ge M$. Each node in the network requests a file from the library independently at random, according to a popularity distribution, and is served by other nodes having the requested file in their local cache via (possibly) multihop transmissions. Under the classical "protocol model" of wireless networks, we characterize the optimal per-node capacity scaling law for a broad class of heavy-tailed popularity distributions including Zipf distributions with exponent less than one. In the parameter regimes of interest, we show that a decentralized random caching strategy with uniform probability over the library yields the optimal per-node capacity scaling of $\Theta (\sqrt{M/m})$, which is constant with $n$, thus yielding throughput scalability with the network size. Furthermore, the multihop capacity scaling can be significantly better than for the case of single-hop caching networks, for which the per-node capacity is $\Theta (M/m)$. The multihop capacity scaling law can be further improved for a Zipf distribution with exponent larger than some threshold $>1$, by using a decentralized random caching uniformly across a subset of most popular files in the library. Namely, ignoring a subset of less popular files (i.e., effectively reducing the size of the library) can significantly improve the throughput scaling while guaranteeing that all nodes will be served with high probability as $n$ increases.

21 pages, 5 figures, submitted to IEEE Transactions on Information Theory

References in corpus (6)

• Order-Optimal Rate of Caching and Coded Multicasting with Random Demands
• Hierarchical Coded Caching
• Fundamental Limits of Distributed Caching in D2D Wireless Networks
• The Throughput-Outage Tradeoff of Wireless One-Hop Caching Networks
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• Information Theoretic Caching: The Multi-User Case
• Cache Placement in Fog-RANs: From Centralized to Distributed Algorithms
• Asymptotic Scaling Laws of Wireless Adhoc Network with Physical Layer Caching
• Coded Caching Clusters with Device-to-Device Communications
• Efficient Scheduling and Power Allocation for D2D-assisted Wireless Caching Networks
• Cache Placement in Two-Tier HetNets with Limited Storage Capacity: Cache or Buffer?
• How to Cache in Mobile Hybrid IoT Networks?
• Throughput Analysis of Decentralized Coded Content Caching in Cellular Networks