Cooperative Tx/Rx Caching in Interference Channels: A Storage-Latency Tradeoff Study

TL;DR

This paper explores the tradeoff between storage capacity and latency in a 3x3 wireless interference network with caches, proposing a cooperative caching strategy and analyzing the resulting performance bounds.

Contribution

It introduces a generic cooperative caching strategy with adjustable file splitting, and derives an upper bound on the minimum fractional delivery time using linear programming.

Findings

Achievable FDT is convex and piece-wise linear decreasing with cache size.

Different cache size regions leverage local caching, multicasting, and cooperation gains.

The strategy transforms interference channels into broadcast, multicast, or X channels.

Abstract

This paper studies the storage-latency tradeoff in the $3\times3$ wireless interference network with caches equipped at all transmitters and receivers. The tradeoff is characterized by the so-called fractional delivery time (FDT) at given normalized transmitter and receiver cache sizes. We first propose a generic cooperative transmitter/receiver caching strategy with adjustable file splitting ratios. Based on this caching strategy, we then design the delivery phase carefully to turn the considered interference channel opportunistically into broadcast channel, multicast channel, X channel, or a hybrid form of these channels. After that, we obtain an achievable upper bound of the minimum FDT by solving a linear programming problem of the file splitting ratios. The achievable FDT is a convex and piece-wise linear decreasing function of the cache sizes. Receiver local caching gain, coded multicasting gain, and transmitter cooperation gain (interference alignment and interference neutralization) are leveraged in different cache size regions.