Universität Karlsruhe (TH) Forschungsuniversität · gegründet 1825 Institut für Nachrichtentechnik Prof. Dr.rer.nat. F. Jondral INT INT From Maxwell‘s Equations to Cognitive Radio Friedrich K. Jondral Lichtenau (Baden), July 2, 2008
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
3Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
Institut für NachrichtentechnikINTINT
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
4Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
Institut für NachrichtentechnikINTINT
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
.
.
5Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
Institut für NachrichtentechnikINTINT
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
6Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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)
7Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
Institut für NachrichtentechnikINTINT
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
8Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
9Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
10Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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Professional Short Wave Receiver (analog)
TELEFUNKENTFK801, ca. 1935
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Mobile Phones
MotorolaRazor, 2005
Applei-Phone, 2007
12Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
13Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
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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
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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?
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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?
17Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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.
18Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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)
19Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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.
20Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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Multi Standard Terminal
GPS GSM, GPRS,EDGE, UMTS,HSPA, S3G, LTE
WiMax
DVB-H
WLAN
Bluetooth
UWB
ZigBee
NFC
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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
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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, ... )
23Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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.
24Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
25Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
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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
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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- …
28Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
29Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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)
30Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
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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
32Universität Karlsruhe (TH)Forschungsuniversität · gegründet 1825
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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
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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
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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