1. New Frontiers in Ubiquitous
Mobile Computing
UT Austin Silicon Valley Event
March 6, 2013
Robert Heath, Gustavo de Veciana, Jeff Andrews,
Sriram Vishwanath, and Ahmed Tewfik
Wireless Networking and Communications Group
http://www.wncg.org

2. Wireless is Big in Texas
20 Faculty 12 Industrial Affiliates
Affiliates
champion
large
federal
proposals,
provide
technical
input/feedback,
unrestricted
gi:
funds
WNCG
provides
pre-­‐prints,
pre-­‐compe@@ve
research
ideas,
vast
exper@se,
first
access
to
students
56%
of
students
full-­‐@me,
54%
of
Affiliates
provide
students
intern
over
the
summer
real
world
context
Heavily funded center
140 Grad Students
$5M
2007-08 2008-09 2009-10 2010-11 2011-12 2

3. Wireless and Beyond
Cellular Networks Architectures Pushing RF Limits
Applications High Dimensional Learning & BigDATA
Security
Identify
ISTOCKPHOTO.COM/© SIGAL SUHLER MORAN
3

4. Technical Snapshots
Is There Really a “Spectrum Crunch”?
Solving the Video Bandwidth Bottleneck
Secure Architectures for Wireless
4

5. The Sky is Falling!
o Mobile data demand increasing at 100-200% a
year, depending on who you ask
§ That’s over a 1000x increase in a decade
o “Almost three years ago we started sounding
the alarm… the debate has been settled. The
plain fact is that aggregate demand is
increasing at very rapid pace, while supply is
flat.”
§ FCC Chairman J. Genachowski, CES, Jan. 11,
2012
o The FCC’s “bold plan”?
§ Add 300 MHz by 2015, 500 MHz by 2020
§ Since 2010, only 25 MHz has actually been
added
5

6. Cellular Networks are Undergoing a
Radical Structural Change: “HetNets”
• Mobile users simply care
whether they can connect at a
high rate and quality Wi-Fi
Femto BS
• Key to user experience is not Femto BS
Pico BS
amount of spectrum
Femto BS
• US WiFi spectrum > 420 MHz
• US Cellular > 550 MHz Macro BS
Femto BS
Wi-Fi
• The key is the amount of
infrastructure Pico BS
• Picocells for hotspots Femto BS
• Femtocells for home and office
• WiFi everywhere A“HetNet”
(single macrocell coverage area)
6

7. Understanding User Rate in HetNets
o The rate (bits/second) is given by a
modification of Shannon’s formula:
B
R= log2 (1 + SINR)
N
o Decreasing the number of users per
base station (N) is equivalent to
increasing the amount of spectrum (B)
7

8. One Answer is More Base Stations
Typical Counter-Arguments
o Won’t adding more
base stations be really
expensive?
o Won’t adding more
base stations increase
the amount of
interference, and result
in a “tragedy of the A plausible 3-tier HetNet
commons” effect? (macro-pico-femto) showing
max-SINR coverage areas in
a given band
The answer to both questions is “No” -- or at least “Not Necessarily”
8

9. Cost is Not a Fundamental Roadblock
o Infrastructure Cost
§ There is no fundamental reason a small BS
needs to cost much more than a WiFi AP
§ Backhaul (and to lesser extent, power) is a
huge issue and an “all of the above” solution
is needed
o Other challenges include:
§ Mobility management
§ Self-tuning and self-organization
§ Open vs. Closed Access
§ Use of 3rd party wired backhaul
9

10. HetNets Can Only Increase Rate
Our research in WNCG at UT Austin has proven:
o Adding base stations of any power, even at random
locations, actually does not change the SINR
distribution in the network (breakthrough HetNet
result)
o Optimal load balancing – pushing users intelligently
onto the smaller cells – in a HetNet is easy and has
a 3x gain
o There is no “interference overload” issue in HetNets
o Our results have been borne out by findings from
Qualcomm, NSN, Samsung, Huawei, NTT Docomo,
and AT&T
J. G. Andrews, “Seven Ways that HetNets are a Cellular
Paradigm Shift”, IEEE Communications Magazine, Mar. 2013.
10

11. Is HetNet the End of the Road?
o mmWave: More spectrum is still good
§ Plenty at mmWave bands that could be exploited
§ Larger bandwidth, reduced interference,
§ Useful for both backhaul and access links
o Antennas: More MIMO doesn’t hurt
§ A few antennas can multiply the bandwidth efficiency
§ Massive numbers of antennas can support many users
and can even simplify processing in massive MIMO
o Coordination: Managing interference makes sense
§ Coordinated interference may cease to be interference
§ Price of coordination does not always outweigh costs
§ Centralized infrastructure is easier to coordinate (cloud)
M. Dohler, R. W. Heath, Jr., A. Lozano, C. Papadias, R. A. Valenzuela, ``Is the PHY Layer
Dead?,'' IEEE Communications Magazine, vol. 49, no. 4, pp. 159-165, April 2011.
11

12. Technical Snapshots
Is There Really a “Spectrum Crunch”?
Solving the Video Bandwidth Bottleneck
Secure Architectures for Wireless
12

13. Explosion of Wireless Digital Video
o Smartphones, Ipads, tablets, laptops, HD content.
o Wireless data traffic is increasing by 100% annually…..66%
expected to be digital video.
o Additional capacity enabled by HetNets, does not resolve per
user capacity variability, posing challenge to video delivery.
13

14. 1. Exploiting Knowledge of Future Capacity
Variations
o Opportunistic scheduling given current capacity variations.
o Opportunistic video delivery exploits knowledge of future
capacity variations and increased storage on mobile devices.
Predictable Capacity
mobility
patterns Poor
coverage
Wireless coverage/capacity landscape Time

15. 2. Optimizing Video Delivery for Humans’
Quality of Experience
video
quality
aversion
+ to variability
in quality
Size/rate
Perceptual aspects Behavioral aspects of
of video quality. video quality, e.g., memory
15

16. 3. Exploiting Heterogeneity of Video Content
Inter-user Heterogeneity
Distinguish users watching
a talk show vs. an HD movie.
Intra-user Heterogeneity
Exploit knowledge of changing
character of video content.
16

17. 4. Learning Users’ Preferences to Better
Manage Video Delivery
cost
rebuffering
quality
Individualized content
specific preferences. Classes of video content
Putting video delivery “intelligence” in mobile (or network).

18. New Video Delivery Infrastructure
o Designing distributed protocols for “optimal” delivery.
o Exploiting knowledge of content, device, wireless
capacity, and users’ preferences to optimize for users’
quality of experience.
o Delivering 50-90% video capacity gains and improved
fairness over state-of-the-art.
18

19. Technical Snapshots
Is There Really a “Spectrum Crunch”?
Solving the Video Bandwidth Bottleneck
Secure Architectures for Wireless
19

20. “The Cloud” is Expanding
o Usage growing faster than Moore’s law
§ $102B in 2012
o Main problem: Reliability, Security and Privacy. Usage by high
assurance domains only possible if these solved.
20

21. The Cloud is Truly Everywhere
Microsoft’s data centers
Issues:
1. The provider may not be trustworthy
2. The VMs on machine may not be secure
3. The hardware itself may be compromised
21

22. Tamper Proof Architecture
Security Protect
Protected Environment"
Kernel
(trusted part
of an OS) I/O"
Identify
Memory"
o Single-chip secure processor
§ basic encryption + integrity checking
o First implementation of an Oblivious RAM
22

23. Integrity Checking Using MACs
Deploying MACs between VMs and servers to control
passive/active adversaries
23

24. Coded Data Storage & Access
o Current approach for storage: replicate
data across servers
o Both wasteful in space and insecure
o Coded strategy:
§ store coded data across servers
§ Require secure collaboration to reconstruct
data
§ Results in simultaneous network and node
security advantages
24

25. Our Research Directions
o A networked cloud + client system with
verifiable properties: high evaluation
assurance rating
o Approach: co-design architecture and
distributed system software with
verification techniques
o Push theory into practice: Full-system
prototypes built on emerging hardware
technologies.
25

26. Wireless is Big in Texas
20 Faculty 12 Industrial Affiliates
Affiliates
champion
large
federal
proposals,
provide
technical
input/feedback,
unrestricted
gi:
funds
WNCG
provides
pre-­‐prints,
pre-­‐compe@@ve
research
ideas,
vast
exper@se,
first
access
to
students
56%
of
students
full-­‐@me,
54%
of
Affiliates
provide
students
intern
over
the
summer
real
world
context
Heavily funded center
140 Grad Students
$5M
2007-08 2008-09 2009-10 2010-11 2011-12 26

27. WNCG Student Presentations
Optimizing Video over Wireless Networks
Presented by Vinay Joseph
Interference Alignment from Information
Theory to Practice Presented by
Omar El Ayach
A Comprehensive Model for
Heterogeneous Cellular Networks
Presented by Harpreet Dhillon
27