D2D Assisted Multi-antenna Coded Caching

TL;DR

This paper introduces a D2D-assisted multi-antenna coded caching scheme that enhances delivery rates and reduces beamforming complexity by combining local D2D exchanges with traditional downlink transmission, optimizing resource use.

Contribution

It proposes a novel two-phase transmission scheme with a low complexity D2D mode selection algorithm, improving content delivery efficiency and reducing beamformer design complexity in multi-antenna systems.

Findings

D2D phase reduces delivery time under certain conditions

Adding D2D improves transmission rate and resource utilization

Significant performance gains in finite SNR regimes

Abstract

A device-to-device (D2D) aided multi-antenna coded caching scheme is proposed to improve the average delivery rate and reduce the downlink (DL) beamforming complexity.} Novel beamforming and resource allocation schemes are proposed where local data exchange among nearby users is exploited. The transmission is split into two phases: local D2D content exchange and DL transmission. In the D2D phase, subsets of users are selected to share content with the adjacent users directly. {In this regard, a low complexity D2D mode selection algorithm is proposed to find the appropriate set of users for the D2D phase with comparable performance to the optimal exhaustive search. {During} the DL phase, the base station multicasts the remaining data requested by all the users. We identify scenarios and conditions where D2D transmission can reduce the delivery time. Furthermore, we demonstrate how} adding the new D2D phase to the DL-only scenario can significantly reduce the beamformer design complexity in the DL phase. The results further highlight that by partly delivering requested data in the D2D phase, the transmission rate can be boosted due to more efficient use of resources during the subsequent DL phase. As a result, the overall content delivery performance is greatly enhanced, especially in the finite signal-to-noise (SNR) regime.