Full-duplex radios for edge caching

Atzeni, Italo; Maso, Marco
Book Chapter N°13 of "Wireless Edge Caching: Modelling, Analysis and Optimization", Cambridge University Press, 2021, ISBN: 9781108480833

Recent studies have shown that edge caching may have a beneficial effect on the sustainability of future wireless networks. While its positive impact at the network level is rather clear (in terms of, e.g., access delay and backhaul load), assessing its potential benefits at the physical layer is less straightforward. This chapter builds upon this observation and focuses on the performance enhancement brought by the addition of caching capabilities to full-duplex (FD) radios in the context of ultra-dense networks (UDNs). More specifically, we aim at showing that the interference footprint of such networks, i.e., the major bottleneck to overcome to observe the theoretical FD throughput doubling at the network level, can be significantly reduced thanks to edge caching. As a matter of fact, fundamental results available in the literature show that most of the gain, as compared to their half-duplex (HD) counterparts, can be achieved by such networks only if costly modifications to their infrastructure are performed and/or if high-rate signaling is exchanged between user equipments (UEs) over suitable control links. Therefore, we aim at proposing a viable and cost-effective alternative to these solutions based on pre-fetching locally popular contents at the network edge. We start by considering an interference-rich scenario such as an ultra-dense FD small-cell network, in which several non-cooperative FD base stations (BSs) serve their associated UEs while communicating with a wireless backhaul node (BN) to retrieve the content to deliver. We then describe a geographical caching policy aiming at capturing local files popularity and compute the corresponding cache-hit probability. Thereupon, we calculate the probability of successful transmission of a file requested by a UE, either directly by its serving small-cell base station (SBS) or by the corresponding BN: this quantity is then used to lower-bound the throughput of the considered network. Our approach leverages tools from stochastic geometry in order to guarantee both analytical tractability of the problem and generality of the results. A set of suitable numerical simulations is finally performed to confirm the correctness of the theoretical findings and characterize the performance enhancement brought by the adoption of edge caching. The most striking result in this sense is the remarkable performance improvement observed when shifting from cache-free to cache-aided FD small-cell networks

Systèmes de Communication
Eurecom Ref:
© Cambridge university press. Personal use of this material is permitted. The definitive version of this paper was published in Book Chapter N°13 of "Wireless Edge Caching: Modelling, Analysis and Optimization", Cambridge University Press, 2021, ISBN: 9781108480833 and is available at : https://doi.org/10.1017/9781108691277.014
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