vehicular communications and networks employing cognitive ... · universal software radio...

Vehicular Communications and Networks Employing Cognitive Radio

Alexander M. Wyglinski, Ph.D.

Associate Professor of Electrical and Computer Engineering

IEEE Vehicular Technology Society Distinguished Lecturer

Worcester Polytechnic Institute

Presentation Outline

• Introduction

• The Information Age

• Wireless Innovation Laboratory

• Vehicular DSA

• Measurement Campaign

• Capacity Analysis

• Experimental Validation

• Concluding Remarks

• More Information

Introduction


Definition: Cognitive radio

A cognitive radio is a kind of two-way radio that automatically changes its transmission or reception parameters, in such a way that the entire wireless communication network - of which it is a node -communicates efficiently, while avoiding interference with licensed or unlicensed users.

A cognitive radio, as defined by the researchers at Virginia Polytechnic Institute and State University, is "a software defined radio with a cognitive engine brain".

http://en.wikipedia.org/wiki/Cognitive_radio


So what is Cognitive Radio?

+ ?


Intelligence

Optim

izat

ion

Adaptation

Environmental Awareness

AgileFlexible

Spectrally Efficient

Learning

Cooperative

Op

po

rtu

nis

tic

Autonomous

Dynamic Spectrum Access

Cognitive radio means …

The Information Age


Several Key Innovators

Marconi Shannon ShockleyBardeen Brittain

Wireless Transmission

Digital Communications

Transistors

Source: Wikipedia


Progress of Technology


Evolution of Wireless Systems“C

ognitiv

e Rad

io C

om

munic

atio

ns

and N

etw

ork

s: P

rinci

ple

s an

d P

ract

ice”

By

A.

M.

Wyg

linsk

i, M

. N

ekove

e, Y

. T.

Hou (

Els

evie

r, D

ecem

ber

2009)


Quick Survey

How many of you:─Own a cell phone?─Use a laptop with WiFi?─Use an ATM?─Fly on a plane?─Traveled in a car?

11


Increasing Demand262 Million Subscribers!

Source: CTIA


Increasing Demand

1.1 Trillion Minutes!

Source: CTIA


US Spectrum Scarcity!

So

urc

e:

NT

IA


Across the Pond in the UK!

So

urc

e:

Ro

ke M

an

or


Oh Canada!S

ou

rce:

Ind

ust

ry C

an

ad

a


Apparent Scarcity

• Measurement studies have shown that in both the time and frequency domains that spectrum is underutilized

Spectrum measurement across the 900 kHz –1 GHz band (Lawrence, KS, USA)

Spectrum Holes


Potential Solution

Spectrum measurement across the 900 kHz –1 GHz band (Lawrence, KS, USA)

• Dynamic Spectrum Access (DSA)

Fill with secondary

users


Enabling Transmission Agility

PROGRAMMABLE FIXED


Sample SDR Platforms

Universal Software Radio Peripheral 2 (USRP2) Unit.

COSMIAC FPGA board currently being retrofitted for better memory access, to add USB functionality and

to make the board SPA compatible.


Mitola & Cognitive Radio

Mitola


Cognitive Radio: A Black Box Model

What you want

What you see

What you can do

What you can tune

Wireless Innovation Laboratory


• Associate Professor, WPI ECE

• Director, Wireless Innovation Laboratory─ 8 Ph.D. students, 5 M.S. students

• Distinguished Lecturer, IEEE Vehicular Technology Society (2012-2014)

• Technical Editor, IEEE Communications Magazine

• Editor, IEEE Transactions on Wireless Communications

• General Co-Chair, IEEE VTC 2015-Fall (Boston, MA, USA)

• ~35 journal publications, ~75 conference papers, 9 book chapters, 2 books

• Served or is serving as PI/co-PI for several federal and industrial grants

Who is Alex Wyglinski?


~60 km

Where is WPI?


• Founded in 1865; 3rd oldest US polytechnic

─ Model for most engineering schools in US

─ Nationally ranked as 64th Best College in U.S. (2011 US News Rankings)

─ Voted one of the Top 10 Best U.S. Colleges for “Young Einsteins” by Unigo (together with MIT, CalTech, Princeton, Dartmouth, Stanford, Johns Hopkins, Case Western, Georgia Tech, and Cornell)

• 3800 students & 220 faculty─ ECE: 318 undegraduate, 250

graduate, 21 faculty

What is WPI?


What is “Lehr und Kunst”?

• Project-based education at the core of “The WPI Plan”

• Many ECE students conduct their senior capstone design projects (called “Major Qualifying Projects”or MQPs) at off-campus locations:─ MIT Lincoln Laboratory─ MITRE (Bedford Campus)─ General Dynamics (Groton Campus)─ Silicon Valley─ Wall Street─ Etc …


Wireless Innovation Laboratory

• 2 USRP (Version 1) software-defined radio platforms

• 14 USRP (Version 2) software-defined radio platforms

• 15 USRP (Version N210) software-defined radio platforms

• 1 Agilent CSA N1996A 0-3 GHz spectrum analyzer (with battery packs)

• 1 Mini-discone antenna (100 – 1600 MHz, with 3’ tripod)

• 1 WG horn antenna (0.7 – 18.0 GHz, with tripod)

• 1 Xilinx Virtex 5 HW-V5-ML506-UNI-G Prototyping Board

• 25 complete licenses of MATLAB and Simulink with associated toolboxes and blocksets

• 2 OPNET licenses


WI Lab External Sponsorship

Vehicular DSA


• Several automobile manufacturers are looking at increasing the level of information connectivity amongst road vehicles

• Several technological initiatives are underway for developing vehicular communications─US Dept. of Transportation’s IntelliDrive

program to provide V2V and V2I communications

Emergence of Vehicular Comms


• Vehicular communications have several uses─ Emergency information Deer, road conditions, sudden traffic situations

─ Infotainment Sharing Disney DVDs between minivans

─Obtaining diagnostic information from the vehicle itself Remote roadside assistance

─Supporting autonomous system implementations “Platooning”, self-driving vehicles

Different Supported Applications


DTV Spectrum an Attractive Option!


Vehicular Dynamic Spectrum Access


Notice how the spectrum occupancy changes as a function of distance!

Spectrum Occupancy as a Function of Speed???

Measurement Campaign


• Although spectrum occupancy models give part of the story, empirical measurements can help provide further insights

• Forty eight locations chosen across I-90 in the state of Massachusetts approximately 2 miles apart

• Spectrum measurements taken in a moving vehicle on 06/30/2009

Understanding of DTV Spectrum


A map of the locations close to I-90 between Boston, MA and West Stockbridge, MA over which spectrum measurements were collected on 06/07/2009, 06/11/2009, 06/12/2009 and

06/30/2009

Measurement Locations

~217 km


• Measurement setup consists of─ A spectrum analyzer,─ A laptop installed with

SQUIRREL (both of them located inside the car) and

─ A mini-discone antenna

• Frequency resolution chosen – 20 kHz

• Time sweeps per site – 10

Measurement Setup


Frequency (in MHz)

Sw

eep

Inde

x

500 550 600 650 700 750

50

100

150

200

250

300

350

400

450

-120

-110

-100

-90

-80

-70

-60

-50

Energy Spectral Density plots for the TV frequencies in the higher frequency range i.e.,

470 – 806 MHz across 48 locations close to I-90 between Boston, MA and West Stockbridge, MA.

Boston

MA/NY

Worcester

Raw Measurements


TV Channel availability at different locations along I-90 in the state of Massachusetts.

Spectrum Occupancy Results


The total available bandwidth for secondary usage at different locations along I-90 in the state of Massachusetts.

How does low bandwidth availability

coupled with high traffic density affect secondary access to wireless spectrum?

How does low bandwidth availability

coupled with high traffic density affect secondary access to wireless spectrum?

Available Bandwidth

Capacity Analysis


• Model bandwidth resources as servers─ In queuing theory one job at a time per

server

• Model bandwidth requests made by vehicles as service requests from users

• Model sub-channel occupation time of each request as the service time of each job

• Multi-server model with a single queue

Problem Formulation


TV bands

Quit bandCh 21

Ch 22

Ch 51

Service time :General,Deterministic,Exponential,…

Model Functionality


• This model incorporates location dependent channel availability change by turning on/off servers

• Channel availability depends on─Spatial-temporal channel availability

map─Vehicle location and current time Function of speed and location on the

highway

DTV Spectrum Map


Bandwidth requests

TV bands

Server down if

occupied by PU

Suppose same λfor all cars of the

same priority class, N changes

depending on time and location

Priority Access


Predicted performance measures in the case when all cars are of the same priority, where M/D/m model assumes deterministic service time, and M/M/m model

assumes exponential service time.

Results


Predicted performance measures in the case where cars have different priorities and same message rate of 60 msg/sec. The number of higher class customers is 10% that

of lower class customers. M/D/m model assumes deterministic service time, and M/M/m model assumes exponential service time.

Results

Experimental Evaluation


• Various research efforts into assessing the feasibility of performing DSA within vehicular networks─ Examination of candidate frequency bands for supporting

VDSA networks─ Defining networking protocols for enabling VDSA

communications─ Assessment of theoretical capacity for VDSA networks

• There have only been a couple of attempts to experimentally assess VDSA in hardware─ IEEE WiVec 2011: “The Kyushu Experiment”

Theory & Simulation Are Nice But ...


Isolated region on the island

of Kyushu

First Point-to-Point DTV VDSA Experiment!


So how do you do VDSA

experimentally?


Step 1: Dedicated Students

December 2010


Step 2: Students with Cars


Step 3: Lots of SDRs!!

Cre

dit

: G

eorg

e E

ich

ing

er, 2

011


Step 4: Gather Results

Secondary wireless of vehicular communications

Experimental results for the WI Lab VDSA experimental test-bed.

A

BC

D

Multi-hop VDSA transmissions via vehicles ABCD

Concluding Remarks


These are interesting times!

• Numerous advances in cognitive radio, dynamic spectrum access, and software-defined radio have recently occurred─ Secondary access of digital TV spectrum─ Ratification of IEEE 802.22, IEEE 802.11af standards

• Today’s wireless landscape is quickly changing due to new capabilities of wireless transceiver devices─ Largely due to smaller, faster processing devices resulting

from applications such as smart phones


Still room for improvement

• There still exists a substantial amount of research that is needed to make future wireless devices such as cognitive radio more reliable─ Ensuring minimal interference to other wireless

transmissions─ Enabling real-time decision-making and transmission

operations─ Making RF spectrum access more reliable for everyone

involved

More Information


Contact Info

Professor Alexander Wyglinski

Department of Electrical and Computer EngineeringWorcester Polytechnic Institute

Atwater Kent Laboratories, Room AK230

508-831-5061

[email protected]

http://www.wireless.wpi.edu/


Cognitive Radio Textbook

Available since December 2009 (Academic Press)

20 chapters

End-of-chapter problems (with solutions guide)

Presentation slides for most chapters

Covers physical and network layers, in addition to current platforms and standards


New SDR Textbook

• January 2013 Publications Date (Artech House Publishers)

• 9 comprehensive chapters ─ Fundamentals in signals &

systems, probability, and digital communications

─ “Hands on” approach to learning digital communication concepts using SDR and Simulink

─ End-of-chapter problems─ Corresponding course

lecture slides

http://www.sdr.wpi.edu/

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