From Maxwell‘s Equations to Cognitive Radio - … Maxwell‘s Equations to Cognitive Radio ... analog digital multi carrier spread spectrum. ... Facilitate multi-band multi-standard

Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825

Institut für NachrichtentechnikProf. Dr.rer.nat. F. Jondral INTINT

From Maxwell‘s Equations to Cognitive Radio

Friedrich K. JondralLichtenau (Baden), July 2, 2008

2Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825

Institut für NachrichtentechnikINTINT

Topics

• Historic Remarks

• Radio Communications

• Software Defined Radio

• Cognitive Radio

• Regulation



Some Important Events

GSM, SDR

digital signal processing, DR

audio broadcast

Marconi's experiments

Hertz's experiments

Maxwell equations

1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030

Shannon, television

transistor

UMTS, WLAN, CR



The Starting Point

James Clerk Maxwell, 1831 – 1879

There is nothing as practical as a convincing theory.

Maxwell's equations (1873)

magnetic fieldelectric fieldelectric displacementmagnetic flux densitycurrent densityvolume charge density

rot H J D= +v v v

rot E B= −v v

div D = ρv

div B 0=v

Hv

Ev

Dv

Bv

ρJv

.

.



Generation of Sine Waves

Heinrich Hertz, 1857 – 1894Karlsruhe 1887:

Electromagnetic waves propagatethrough free spaceMetallic walls reflect electromagneticwavesElectromagnetic waves exhibit theproperities of light waves (reflection, diffraction, refraction, polarization, interference, ...)

Hertzian dipole

z

x

θ r



Pioneering Radio Experiments

Guglielmo Marconi 1874 – 1937

First radio transmission experiments

• 1899 over the English Channel

• 1901 transatlantic from Poldhu (Cornwall) to Signal Hill / St. John‘s (Newfound-land)



Modulation

α amplitude, fc carrier frequencyϕ phase, fi information frequency

( ) ( ) ( ) ( ){ } c is t a t cos 2 f f t t t= π + +ϕ

DSFHTH

based on FFT• DMT• OFDM• COFDM

ASKFSKPSKQAM

AMSSBRSBFM

spread spectrummulti carrierdigitalanalog



Digitalization / Coding

Sampling theorem, 1949If the real signal s(t) is

integrable over the whole real axisband limited by B, i.e.

thens(t) is determined by its values s(k∆t ),k ∈ Ζ, periodically taken at the time difference

( ) ( ) ( ) s t S f : S f 0 f B• = ∀ ≥o

( ) ( ) ( )( )

∞

=−∞

π − ∆= ∆

π − ∆∑k

sin2 B t k ts t s k t

2 B t k t

∆ =1t

2B :

Claude E. Shannon, 1916 – 2001

Source coding

Channel coding (FEC)

Cryptographic coding



Networking

Radios are normally integrated into networks

In many cases radio networks serve as access networks to fiber optic backbones

We have to distinguish commercial, security and military networks

Autarky is of special interest for military and security applications

Military applications may call for low probability of intercept and for advancedcrypto requirements



Professional Short Wave Receiver (analog)

TELEFUNKENTFK801, ca. 1935



Mobile Phones

MotorolaRazor, 2005

Applei-Phone, 2007



Mobile Spectrum in Europe

2690

5200

890

915

935

960

. . . f [MHz]

1710

1785

1805

1880

1900

1920

1980

2010

2025

GSM DECT UTRA-TDD

2110

2170

2200

UTRA-FDD

5725

5850

MSS

2400

2305

2320

2345

2360

ISM WLAN WiMAXFutureWiMAX

1600 1700 1800 1900 2000 2100 2200 2300 2400 2500

800 1000 1300 1600900 1200 15001100 1400

2483

,5

3300 34002600 2900 32002500 2800 31002700 3000 3500 3600

5100 5300 5400 5500 580057005600 5900

5470

5350

5150



Mobile Standards

user data rate

high velocity

long distance traffic

urban traffic

walking

nomadic

fixed

inhouse

personal environment0.1 1 10 100 Mbit/s

vehi

clest

atio

nary

EDGEHSPA

3G/UMTS

GSM/GPRS

DECT

Bluetooth

flashOFDM

WLAN(IEEE 802.11x)

WiMAXIEEE 802.16-

2004

IEEE 802.16e

3Gsuccessorsystems

>2014

pede

stria

nSource:Klaus-D. Kohrt: 3G und WIMAX –Konkurrenten oder Partner?ntz, Heft 1, 2007, S. 12-15

mobility/range



Hierarchical Cells

Zone 4:Global

Zone 3:Suburban Zone 2:

UrbanZone 1:

In-Building

World-Cell Macro-Cell Micro-Cell Pico-Cell

Source: UMTS Task Force Report



The Key Question

InfotainmentSatellite Networks

Location & NavigationBroadcast Networks

MultimediaGlobal CellsCellular Networks

VideoMacro CellsCordless Phones

DataMicro CellsWireless Local Area Networks

VoicePico CellsPersonal Area Networks

What does a subscriber need?One specific device for each and every situation

or one device that serves all situations?



Standards

Definition:A communications standard is a set of documents that describes the functionsof a communication system in such a way that a manufacturer can developterminals or infrastructure equipment on this basis.

Remarks:(i) Standardization is one necessary condition for making a communication

system successful on the market.

(ii) Today, standardization encompasses all kinds of communication networks.

Will standards continue to play an outstanding role in future communication systems?



Standards Summary

Radio communication standards define transmission systems w.r.t. specificservices like voice, video, data, multimedia, broadcast, location, navigation etc.

The accompanying transmission modes and protocols depend on data rate bandwidth, velocity, type of service etc.

Mobile radio communication starts with the channel properties.



Definitions 1)

Software Radio (SR): An ideal SR directly samples the antenna output.

1) According to J. Mitola, 2000

Digital Radio (DR): The baseband signal processing is invariably implemented on a DSP.

Software Defined Radio (SDR): An SDR is a realizable version of an SR: Signals are sampled after a suitable band selection filter.

trans

mit

rece

ive

radio frontend

radiofrequency

RFbaseband

processing

to u

ser

from

use

r

analog-to-digitalconversion

A/Ddata

processing

control(parametrization)



Radio Evolution

µP-controlledAnalog Radio

Digital Radio

Software DefinedRadio

1980 1990 2000 2010

104

105

106

108

109

1010

Cognitive Radio

Adaptivity increases

No. o

f tra

nsist

ors o

n an

IC

Moore‘s law:The packing density of transistors on an integrated circuit increases by a factor of two every two years.



Multi Standard Terminal

GPS GSM, GPRS,EDGE, UMTS,HSPA, S3G, LTE

WiMax

DVB-H

WLAN

Bluetooth

UWB

ZigBee

NFC



Multi Band, Multi Standard Approach

Integration

• Use technology development (Moore’s law) to miniaturize current solution

• Examples:- On-chip VCOs- Integration of passive components in RF ICs- WCDMA and GSM on general baseband IC

Architecture• Facilitate multi-band multi-standard• Examples:

- Use homodyne instead of heterodyne receivers- SDR- Modular and expandable software architecture

The rightarchitecture

is key



Reuseable Radio Architecture

Customer Applications

Middleware Service Platform

NetworkAccessService

DataCommunication

Services

MMI andMultimediaServices

ApplicationPlatformServices

OperationServices

Hardware Abstraction Layer (HAL)

Product specific Hardware

General radio architectureAll platforms use the same open and stable APIsHardware depends on product configuration (WCDMA, EDGE, GPRS, ... )



Cognitve Radio: Definitions

Joseph Mitola / Gerald Maguire, 1999 (IEEE Pers. Comm., vol. 6, no. 4, 1999):“Radio etiquette is the set of RF bands, air interfaces, protocols, and spatial and temporal patterns that moderate the use of radio spectrum. Cognitive radio extends the software radio with radio-domain model-based reasoning about such etiquettes.”Simon Haykin, 2005 (IEEE J. Select. Areas in Comm., vol. 23, no. 2, 2005):“Cognitive radio is an intelligent wireless communication system that is aware of its surrounding environment (i.e. its outside world), and uses the methodology of understanding-by-building to learn from the environment and adapt its internal states to statistical variations in the incoming RF stimuli by making corresponding changes in certain operating parameters (e.g. transmit power, carrier-frequency and modulation strategy) in real-time, with two primary objectives in mind:

- highly reliable communications whenever and wherever needed;- efficient utilization of the radio spectrum.”

Friedrich K. Jondral, 2005 (EURASIP J. on Wireless Comm. and Networking, 2005, no. 3):“A cognitive radio (CR) is an SDR that additionally senses its environment, tracks changes, and reacts upon its findings. A CR is an autonomous unit in a communications environment that frequently exchanges information with the networks it is able to access as well as with other CRs.”BNetzA, 2006:Cognitive radio is a radio or system that senses and is aware of its operational environment and can dynamically and autonomously adjust its radio operating parameters.Note: Cognitive radio may benefit from SDR implementation techniques.



Cognitive Radio: Tasks

Evaluate the actual transmission request: Data rate, BER, delay, …, own location, partner’s location, timeChoose the suitable transmission mode: Modulation, coding, MIMO, transmit power, …, w.r.t. the hardware available, the interference temperature limitLook for a transmission resource: Spectrum holesGet in touch with the communications partner: Negotiate about the resource to be used, agree upon possible alternatives and upon the transmission mode for the reverse link, exchange channel state information (CSI)Choose the suitable receiver adjustment



Cognitive Characteristics

Awareness (with respect to the transmitted waveform, RF spectrum, communication network, localization and geography, available services, user needs, language, situation, security policy, …)IntelligenceLearningAdaptivityReliabilityEfficiency



Mitola’s Cognition Cycle

A necessary condition for highest flexibility in mobile communications is a general rethinking in spectrum allocation: Open accessIn order to make open access feasible Cognitive Radios are necessary.

Immediate Urgent Normal

ACT

OutsideWorld

NewStates

PriorStates

OBSERVE LEARN

DECIDE

PLAN

GenerateAlternatives

EvaluateAlternatives

ORIENTEstablish Priority

Receive a MessageRead Buttons

Send a Message Initiate Process(es)

Register toCurrent Time

Pre-ProcessParse

Save Global States

Allocate Resources

Set Display

Infer on ContextHierarchie

Source:Joseph Mitola III: Cognitive Radio – An IntegratedAgent Architecture for Software Defined Radio. KTH Stockholm, 2000



CR Properties

Mitola's cognition cycle is very general. The properties of cognitive radios may be divided into two groups

user centric properties (support functions like finding an appropriate restaurant, recommendation of a travel route, supervision of apointments, . . .)

technology centric properties- spectrum monotoring- localization- awareness of processing capabilities (partitioning and scheduling of

processes)- information and knowledge processing- time- …



Technology Centric Cognitive Radio

Station BStation A

Transmission

Channel measurement and modeling

Reception

Monitoring

SpectralEnvironment

AvailableChannel Capacity

Transmission Power and SpectrumManagement

InterferenceTemperature

Spectrum HolesNoise StatisticsTraffic Volume

RF Signals

Channel measurement and modeling

Reception

Monitoring

SpectralEnvironment

AvailableChannel Capacity

Transmission Power and SpectrumManagement

InterferenceTemperature

RF Signals

Spectrum HolesNoise StatisticsTraffic Volume



Regulation

Today “spectrum“ is regulated by governmental agencies, e.g. the American Federal Communications Commission (FCC) or the Bundesnetzagentur (BNetzA)“Spectrum“ is assigned to users or licensed to them on a long term basisnormally for huge regions like whole countriesThis may lead to wasting of resourcesVision: Resources are assigned where and as long as they are needed, spectrum access is organized by the network (i.e. by the end users)



Spectrum Utilization Measurements(550-1000MHz)

density of thetime between

arrivalsdBs-1

density of thetime between

arrivalsdBs-1

electricfield strength

dBµV/m

electricfield strength

dBµV/m

Lichtenau (Germany), September 2001



Self Regulation

Wireless LANs (IEEE 802.11x)ISM band: 2400 – 2483.5 MHzWLAN band: 5150 – 5350 MHz and 5470 – 5725 MHz Ultra Wide Band

−40

−55

−70

−45

−60

100

101

−50

−65

Frequency in GHz

UWB

EIRP

Em

issio

n Le

vel in

dBm

fc greaterthan 3.1 GHz

fc less than960 MHz

Part 15 Limit



Advanced Spectrum Management

Spectrum reallocation: The reallocation of bandwidth from government or other long-standing users to new services such as mobile communications, broadband internet access, and video distribution.Spectrum leases: The relaxation of the technical and commercial limitations on existing licensees to use their spectrum for new or hybrid (for example, satellite and terrestrial) services and granting most mobile radio licensees the right to lease their spectrum to third parties.Spectrum sharing: The allocation of an unprecedented amount of spectrum that could be used for unlicensed or shared services.

Source:G. Staple, K. Werbach: The End of Spectrum Scarcity. IEEE Spectrum, March 2004, pp. 41-44



Cognitive Radio: Spectral Efficiency*)

CR technology is perfectly suited to opportunistically employ the wireless spectrumFlexible spectrum utilization is allowed by

● frequency agility● dynamic frequency selection● adaptive modulation● transmit power control● location awareness● negotiated use

CRs could skillfully navigate their way through interference and greatly improve spectral efficiencyFCC and other regulators are altering their rules in order to allow for more flexible use of the licensed wireless spectrum

*) from N. Devroye, P. Mitran, V. Tarokh: Limits on Communications in a Cognitive Radio Channel.IEEE Communications Magazine, June 2006, pp. 44-49



Secondary Frequency Markets*)

Spectrum leasing: Allowing unlicensed users to lease any part or all of the spectrum of a licensed userDynamic spectrum leasing: Temporary and opportunistic usage of spectrum rather than a longer-term subleasePrivate commons: A licensee could allow unlicensed users access to his spectrum without a contract, optionally with an access feeInterruptible spectrum leasing: Suitable for a lesser that wants a high level of assurance that any spectrum temporarily in use, or leased, to an incumbent CR could be efficiently reclaimed if needed**)

*) from N. Devroye, P. Mitran, V. Tarokh: Limits on Communications in a Cognitive Radio Channel. IEEE Communications Magazine, June 2006, pp. 44-49**) e.g. T. A. Weiss, F.K. Jondral: Spectrum Pooling: An Innovative Strategy for the enhancement of Spectrum Efficiency. IEEE Communications Magazine, Radio Communications Supplement, March 2004, pp. S8-S14



Thank you!

www.int.uni-karlsruhe.de

Documents

From Maxwell‘s Equations to Cognitive Radio - … Maxwell‘s Equations to Cognitive Radio ... analog digital multi carrier spread spectrum. ... Facilitate multi-band multi-standard