© British Telecommunications plc Cognitive Radio Research at BT Dr Maziar Nekovee BT Innovate and...

transcript

Cognitive Radio Research at BT

Dr Maziar NekoveeBT Innovate and Design & University College London

maziar.nekovee@bt.com

Demand for mobile wireless communications

But also • Home networks (e.g.

HDTV streaming)• Smart metering• RFID• Machine-to-machine

(e.g. intelligent transport systems)

• Developing countries

Key resource: Radio Spectrum

UK Industry paid over 20 billion pound for 140 MHz 3G spectrum

Who “owns” all the spectrum and why is it scarce?

Solution 1: spectrum trading (Cave’s Report)

Command & Control Zone

Ofcom manages it

Market Forces ZoneCompanies manage it

Licence-exempt Zone Nobody manages it

Approach that was adopted for about 94% of

the spectrum

Approach advocated by Cave and implemented

by trading and liberalisation

Approach currently adopted for 6% of

spectrum, some argue for radical increase

2004 6% 7% 20102004 0% 72% 20102004 94% 21% 2010

Source: William Webb, Ofcom

Solution 2: Opportunistic Spectrum Access

Source: Yucek and Arsalan, IEEE Comm. Surveys and Tutorial, 2009

Cognitive RadioEnabling technology for OSA, …and much more

Cognitive Cycle Joseph Mitola III

Cognitive Access to TV White Spaces: Spectrum Opportunity and Technology Challenges

What are TV White Spaces?

Cognitive radios can use channels {A1,A2,A3,B1,B2,B3,C1,C2,C3

Provided they do not cause harmful interference to TV receivers within the coverage areas of A, B, C, and to wireless microphones (PMSE)

How much TVWS is there?

Source: Ofcom Consultation on Cognitive Access, 9 February 2009

256 MHz interleaved spectrum (total UK 3G spectrum 140 MHz!)

US auction of cleared TV spectrum raised $25 billion in 2008

However, the availability varies strongly with location and trasmit power, but how exactly?

Quantifying TVWS availability in the UK

'( , ) | |cr M MM

r P r r R

: Service radius of TV transmitter M (from database)

, : tranmit powers of TV,CR transmitters

: sensitivity threshold of TV receivers

: pathloss exponent

crM M th

cognitive device

'( , ) | |cr M MM

r P r r R r r

Total number of available channels for CR at location r

Regional variations in TVWS spectrum for cognitive access

8 MHz/channels

London

bridge

Cardiff

Ipswich

Liverpool

Source: Nekovee, Proc. IEEE ICC 2009

Bristol

Manchester

Oxford B

irmingh

Glasgo

Thuriso N

ewcastle

0n average 150 MHz at any location in the UK

Spectrum identification/interference avoidance

• Single-device detection – Sensing below thermal noise

levels!

• Cooperative detection– Certification difficult– Spectrum sensor nets– Security issues

• Spectrum database– Favoured by FCC and Ofcom

Microsoft, Google and BT– Wireless microphones are tricky– Requires location-awareness

Detecting DVBT signals below noise levels

• Energy detection

• Feature detection (increased complexity)

– Autocorrelation– Cyclic prefix– Eigen value detection

Source: Wang, Pervez, Nekovee, 2009

Potential applications: system-wide studies Home Networks Rural Broadband

Mobile Broadband without 3G/4G?

IEEE 802.22 standard

Living Room

Bedroom 1Bedroom 2

Kitchen

Deck/Patio

Broadband Internet Connection

CogNea Standard

Proposition A: Home Networks

TVWS Set-top Box

HDTV data via TVWS

mobile device BT Homehub

network

BT TVWS database

1. Queries TVWS database

2. Provides available TVWS channels and power levels

device data via WiFi

• Architecture– Point-to-Multipoint– Master-Slave

CogNea Standard (Philips, Samsung, BT)

Interference study, scenario modeled

• Square kilometre of central London• 40% houses (out of total 5000)

selected with home hubs• Same service requirement 2 Mb/s, 6

Mb/s @ 12m range• With three interference loadings

– Video-streaming only traffic profile – worst case scenario

– Traffic profile mix of voice, video, data corresponding to 2 Mb/s

– Traffic profile mix of voice, video, data corresponding to 6 Mb/s

TVWS Spectrum in Central London

available channels

Source: Kawade, Nekovee, IEEE DySPAN 2010 (submitted)

Technical assumptions for comparing various options

Parameters LTE HSPA WiFi@2.4 GHz 11n WiFi@5.4 GHz 11n802.11 TVWS

Centre Frequency 2.6 GHz 2.1 GHz 2.4 GHz 5.4, 5.8 GHz 400-862 MHz

EIRP 20d dBm 14 dBm 20 dBm 23, 30 dBm 3, 9 dBm

Channel Bandwidth 20 MHz 5 MHz 20 MHz20 (40 MHz

optional) 8 MHz

Antenna scheme None None 2x1 STBC 2x1 STBC None

Wireless Interface OFDM D/L CDMA OFDM OFDM OFDM

Duplex FDD FDD TDD TDD TDD

Modulation & Coding schemes

1/2, 3/4 QPSK1/2, 3/4 16-QAM

1/2, 2/3, 3/4, 5/6, 1/1 64-QAM

1/2, 3/4 QPSK1/2, 3/4, 5/6, 1/1 16-

QAM5/6, 1/1 64-QAM

1/2, 3/4 BPSK1/2, 3/4 QPSK1/2 16 QAM

2/3, 3/4 64 QAM

Other assumptions: • MAC layer overheads were assumed to be approximately 30% of the raw wireless link rate• No antenna scheme considered for TVWS band due to λ/2 restriction

however CogNeA (Philips, Samsung, Texas, HP) propose some antenna scheme/MIMO for laptops in higher UHF (in the other end of TVWS spectrum)

Outage clients (< 1 Mb/s) : 3%

Service requirement 2 Mb/s: 97%

Service requirement 6 Mb/s :50%

TVWS performance results (3/3)

Source: Kawade, Nekovee, IEEE DySPAN 2010 (submitted)

Nomadic/Mobile broadband with BT FON

•Cooperative scheme for sharing home WiFi

•Over 1 million BT FONs, and growing

TV transmitter

Cognitive Radio: A longer term view

A quasi-continuum spectrum

CR2CR1 CR3

Now Future

Dynamic spectrum pooling based on user requirements, availability, and price

An elementary sub-channel

Source: Nekovee, Proc. CrownCom 2008

Spectrum portfolio

Choose a spectrum band Click on the item below to connect to BT Network via one of the available spectrum bands

TV White Spaces

free of charge (cognitive only)

3G Spectrum Vodafone

£0.0012 per second (licensed or cognitive only)

Radar spectrum

ISM bands

free of charge (best effort)

2G Spectrum Orange

3G Spectrum 3

Refresh spectrum list

Setup an automated spectrum manager

Learn about cognitive spectrum access

Change the order of preferred spectrum

Change advanced settings

Cognitive Spectrum Access

Our research interests/activities

• Technologies and models• System-wide issues: multi-user access (etiquette), capacity and

coverage, QoS and mobility• Agile modulation (NC-OFDM) and channel bundling techniques• Cognitive radio testbed and trials • Sensing, antenna arrays and MIMO for cognitive access• Cognitive radio +optical communication?• Spectrum micro auctions• Spectrum databases

• Application Scenarios• Future home networks• Mobile/nomadic broadband• Smart metering • Cognitive Femtocells• Cognitive radio in vehicles

Collaborations

•2 large FP7 projects (starts Jan 2010)

•Microsoft, Google, BBC, CogNea

•Scottish Universities

•Open to exploring new ones!

In press

© British Telecommunications plc Cognitive Radio Research at BT Dr Maziar Nekovee BT Innovate and...

Documents