Graduate School and Research Center in Digital Sciences

Fundamental limits of wireless caching under mixed cacheable and uncacheable traffic

Joudeh, Hamdi; Lampiris, Eleftherios; Elia, Petros; Caire, Giuseppe

Submitted on ArXiV, 20 February 2020

We consider cache-aided wireless communication scenarios where each user requests both a file from an a-priori generated cacheable library (referred to as 'content'), and an uncacheable 'non-content' message generated at the start of the wireless transmission session. This scenario is easily found in real-world wireless networks, where the two types of traffic coexist and share limited radio resources. We focus on single-transmitter, single-antenna wireless networks with cache-aided receivers, where the wireless channel is modelled by a degraded Gaussian broadcast channel (GBC). For this setting, we study the delay-rate trade-off, which characterizes the content delivery time and non-content communication rates that can be achieved simultaneously. We propose a scheme based on the separation principle, which isolates the coded caching and multicasting problem from the physical layer transmission problem. We show that this separation-based scheme is sufficient for achieving an information-theoretically order optimal performance, up to a multiplicative factor of 2.01 for the content delivery time, when working in the generalized degrees of freedom (GDoF) limit. We further show that the achievable performance is near-optimal after relaxing the GDoF limit, up to an additional additive factor of 2 bits per dimension for the non-content rates. A key insight emerging from our scheme is that in some scenarios considerable amounts of non-content traffic can be communicated while maintaining the minimum content delivery time, achieved in the absence of non-content messages; compliments of 'topological holes' arising from asymmetries in wireless channel gains.    

Arxiv Bibtex

Title:Fundamental limits of wireless caching under mixed cacheable and uncacheable traffic
Department:Communication systems
Eurecom ref:6181
Copyright: © EURECOM. Personal use of this material is permitted. The definitive version of this paper was published in Submitted on ArXiV, 20 February 2020 and is available at :
Bibtex: @inproceedings{EURECOM+6181, year = {2020}, title = {{F}undamental limits of wireless caching under mixed cacheable and uncacheable traffic}, author = {{J}oudeh, {H}amdi and {L}ampiris, {E}leftherios and {E}lia, {P}etros and {C}aire, {G}iuseppe}, booktitle = {{S}ubmitted on {A}r{X}i{V}, 20 {F}ebruary 2020}, address = {}, month = {02}, url = {} }
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