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

Wireless is Big in Texas 20 Faculty

140 Grad Students

12 Industrial Affiliates

2007-08 2008-09 2009-10 2010-11 2011-12

$5M

Heavily funded center

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  students  intern  over  the  summer  

Affiliates  provide  real  world  context  

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Wireless and Beyond

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Pushing RF Limits Cellular Networks Architectures

High Dimensional Learning & BigDATA Applications

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Security

Identify

Technical Snapshots

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Solving the Video Bandwidth Bottleneck

Is There Really a “Spectrum Crunch”?

Secure Architectures for Wireless

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

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Cellular Networks are Undergoing a Radical Structural Change: “HetNets”

•  Mobile users simply care whether they can connect at a high rate and quality

•  Key to user experience is not amount of spectrum •  US WiFi spectrum > 420 MHz •  US Cellular > 550 MHz

•  The key is the amount of infrastructure •  Picocells for hotspots •  Femtocells for home and office •  WiFi everywhere A“HetNet”

(single macrocell coverage area)

Macro BS

Femto BS

Femto BS

Femto BS

Pico BS

Femto BS

Pico BS

Wi-Fi

Femto BSWi-Fi

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Understanding User Rate in HetNets o The rate (bits/second) is given by a

modification of Shannon’s formula:

o Decreasing the number of users per base station (N) is equivalent to increasing the amount of spectrum (B)

R =

B

Nlog2(1 + SINR)

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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 commons” effect?

A plausible 3-tier HetNet (macro-pico-femto) showing max-SINR coverage areas in a given band

The answer to both questions is “No” -- or at least “Not Necessarily”

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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

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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.

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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.

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Technical Snapshots

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Solving the Video Bandwidth Bottleneck

Is There Really a “Spectrum Crunch”?

Secure Architectures for Wireless

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.

Explosion of Wireless Digital Video

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1. Exploiting Knowledge of Future Capacity Variations

Poor coverage

Capacity

Time

o  Opportunistic scheduling given current capacity variations. o  Opportunistic video delivery exploits knowledge of future

capacity variations and increased storage on mobile devices.

Wireless coverage/capacity landscape

Predictable mobility patterns

2. Optimizing Video Delivery for Humans’ Quality of Experience

Size/rate

video quality

aversion to variability in quality

+

Perceptual aspects of video quality.

Behavioral aspects of video quality, e.g., memory

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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.

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4. Learning Users’ Preferences to Better Manage Video Delivery

Classes of video content

cost

quality

rebuffering

Putting video delivery “intelligence” in mobile (or network).

Individualized content specific preferences.

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.

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Technical Snapshots

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Solving the Video Bandwidth Bottleneck

Is There Really a “Spectrum Crunch”?

Secure Architectures for Wireless

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.

“The Cloud” is Expanding

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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

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Tamper Proof Architecture

o  Single-chip secure processor §  basic encryption + integrity checking

o First implementation of an Oblivious RAM

Protected Environment"

Memory"

I/O"

Security Kernel

(trusted part of an OS)

Protect

Identify

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Deploying MACs between VMs and servers to control passive/active adversaries

Integrity Checking Using MACs

Coded Data Storage & Access

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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

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.

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Wireless is Big in Texas 20 Faculty

140 Grad Students

12 Industrial Affiliates

2007-08 2008-09 2009-10 2010-11 2011-12

$5M

Heavily funded center

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  students  intern  over  the  summer  

Affiliates  provide  real  world  context  

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WNCG Student Presentations

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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