Advanced Caching: a Paradigm Shift in Wireless Communications

Professor Petros Elia
Lecturer's institute: 
Eurecom, France
21.2.2018 09:00 to 22.2.2018 17:00

Infotech Oulu Lecture Series


The course is mainly targeted for doctoral students, but master students are also welcome. The course
will be administered as 521318S Modern Topics in Telecommunications and Radio Engineering such
that its inclusion in M.Sc. degree is also possible.
Each student needs to solve in total 4-6 problems. Return your solutions as PDF (a scan of hand-written
solutions is fine) by e-mailing to Antti Tölli ( by Monday, 30 April 2018 latest. The time for
the final exam will be announced during the course.


This tutorial is about a new way of seeing caching, and it is about the recently discovered deep
connections between memory/caching and the information-theoretic fundamentals of communications.
The tutorial will be about a new technology that – at first indications – has the potential to approach the
long-sought holy grail of wireless communications, which is to serve an ever increasing number of users,
with a fixed amount of bandwidth resources.
The goal of this tutorial is to help the audience understand how the classical communication “signalseparation”
techniques, are intimately intertwined with novel caching techniques. We will explore how this
combination of communications-techniques and caching can achieve unprecedented throughput gains,
and how it promises to change the way PHY-based communications are conducted. While traditional
caching (prefetching/data-push) methods mainly reduce the volume of the problem for the day after
(reflecting the old saying “Do something today, so that you do not have to do it tomorrow”), the
combination of advanced PHY and caching – instead of changing the volume of the problem – seeks to
change the structure of the problem.
In the end, this tutorial will provide a new look at the recent efforts to employ memory-aided
communications “on top” of physical layer communications. We will also discuss the different new
directions that are inspired by the transition from the wired to the wireless medium; a transition that seems
to entirely change the core of how memory must be used.


Outline of the lectures
Outline of the Tutorial, and Material to be covered

Wednesday, 21 February Morning 9:00-12:00 am – SÄ102:
Advanced caching: Motivation, Introduction and the very basics
 Basic exposition of the challenges of modern wireless communications
 Opportunities and bottlenecks in different PHY technologies like Massive MIMO, and multi-cell
cooperation and densification
 The need of a new communications technology
 Brief introduction to cache-aided solutions
 Basic elements of coded caching
 Local vs. global caching gains
 Centralized vs. decentralized coded caching in multicast settings
 Exploiting file popularity
 Multiple groupcast index coding, and other techniques
 Performance outer bounds – basic exposition
 Joint considerations of caching and network topology
 Exponential subpacketization of coded caching (basic aspects)

Wednesday, 21 February Afternoon, 13:00-16:00 pm  IT116:
Advanced and coded caching in wireless communications
 Some differences between wired and wireless coded caching
 Caching in feedback-aided multiuser MIMO settings
 Joint caching and precoding schemes
 Centralized multi-server problem: ripping the gains of both words
 Caching at both transmitters and receivers (Cache-aided interference channel)
 The fundamental interplay between coded-caching and feedback
 Competing + synergistic duality between feedback and caching
 Caching to achieve interference management
 Caching at the transmitters to achieve interference alignment
 Caching to give receivers, interference-reducing side information
 Coded-caching as a means of creating joint-transmission opportunities

Thursday, 22 February morning, 9:00-12:00 am TS128:
Advanced caching: topology and feedback considerations
 Exploring the interplay between coded caching and feedback
 Achieving an exponential utility of caching in MIMO settings
 Combining multicast gains from caching, with broadcast gains from feedback-aided multiuser MIMO
 Interesting (competing + synergistic) duality between feedback and memory (caching)

 Coded caching in a variety of wireless networks
 Wireless multihop D2D caching networks
 Cache-aided Wyner networks
 Coded caching in erasure networks
 Femtocaching
 Caching on the edge
 Source-coding view of coded caching
 Connections between coded caching and index coding

Thursday, 22 February afternoon, 14:00-17:00 pm TS128:
Recent developments, related fields, and open challenges
 Connections to distributed computing
 Ameliorating the subpacketization bottleneck of coded caching
 Ameliorating the CSI bottleneck of coded caching
 Ameliorating the privacy bottleneck of caching
 Theoretical and practical open problems, and the need to incorporate advanced Signal Processing
techniques (can be perceived as open problems)
 The exponential refinement problem (exponential caching problem - possible alleviations)
 Topology (weakest guy brings down everyone, unless …).
 Linear barrier of coded caching (modest gains for modest-sized caches).

Petros Elia is a professor with the Department of Communication Systems at EURECOM in
Sophia Antipolis, France. He received the B.Sc. degree from the Illinois Institute of Technology,
and the M.Sc. and Ph.D. degrees in electrical engineering from the University of Southern
California (USC), Los Angeles, in 2001 and 2006 respectively. His latest research deals with the
intersection of coded caching and feedback-aided communications in multiuser settings. He has
also considered different problems in the area of complexity-constrained communications,
MIMO, cooperative and multiple access protocols and transceivers, complexity of
communication, as well as with isolation and connectivity in dense networks, queueing theory
and cross-layer design, coding theory, information theoretic limits in cooperative
communications, and surveillance networks. He is a Fulbright scholar, the co-recipient of the
NEWCOM++ distinguished achievement award 2008-2011 for a sequence of publications on
the topic of complexity in wireless communications, and the recipient of the ERC Consolidator
Grant 2016 on cache-aided wireless communications.


Last updated: 12.2.2018