11 May 2017

Weekly Seminar: “Two Ideas for Low Cost Mobile Edge Caching: Modeling and Optimization”

11 May 2017 - 11 May 2017


Pushing popular content to small cells (often referred to as “helper” nodes) during off-peak hours has recently been proposed to cope with the increase in mobile data traffic. User requests can be served locally from these helper nodes, reducing the backhaul/core load for the operator as well as improving user QoE. Nevertheless, size limitations of edge caches and CAPEX/OPEX considerations for new small cells raise some questions about the real potential of mobile edge caching. In this talk, we will discuss two ideas to increase the amount of traffic offloaded to local communications, that can lower the cost for the operator without compromising user QoE. The first is the idea of “soft” cache hits, where if the original content is not available locally, some related contents that are locally cached can be recommended instead. Given that Internet content consumption is entertainment-oriented, we argue that there exist scenarios where a user might accept an alternative content (e.g., better download rate for alternative content, low rate plans, recommendation-driven consumption like YouTube, etc.). We formulate the problem of optimal edge caching with soft cache hits in a relatively generic setup, propose efficient algorithms, and analyze the expected gains. The second idea is to use moving vehicles (e.g. buses, taxis, private cars) as mobile relays and storage points, and use them to aggressively prefetch video chunks used for streaming. We model the playout buffer using queueing theory, and show that the combination of fast mixing (due to vehicles’ mobility) and proper caching can lead to significant amounts of traffic offloaded to the vehicular cloud, without any additional impact on user QoE.



Thrasyvoulos Spyropoulos is an Assistant Professor in Eurecom, Sophia-Antipolis. He holds a PhD degree from the University of Southern California (USC), Los Angeles and a diploma in Electrical and Computer Engineering from the National Technical University of Athens (NTUA). Before joining EURECOM he spent a year as a post-doctoral researcher at INRIA, Sophia-Antipolis, and 3 years as a Senior Researcher and Lecturer at ETH Zurich. His research interests include performance analysis and optimization of 5G networks, content-centric systems, delay-tolerant networks, mobility modeling, and social networks. He has co-authored more than 70 publications in international conferences and journals, has served in the TPC of top-tier conferences, such as ACM Mobihoc, ACM Sigmetrics, and IEEE Infocom, and has co-chaired the ACM CHANTS 2013 and IEEE NetSciCom 2014 workshops. He is also the co-recipient of the best paper awards at IEEE Secon 2008, IEEE WoWMoM 2012, and best paper award runner-up for ACM Mobihoc 2011 and IEEE WoWMoM 2015. More information can be found at http://www.eurecom.fr/~spyropou/