Cognitive Radio From Utopia to Reality by P.pawelczak

8/8/2019 Cognitive Radio From Utopia to Reality by P.pawelczak

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Faculty of Electrical Engineering, Mathematics and Computer Science

Delft University of Technology

Cognitive Radio:From Utopia to Reality

Freeband Ambient Communication Event, Enschede

Przemysaw Paweczak

July 4, 2006


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Background

History: why cognitive radio? (Mitolas definition, spectrum utilization)


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Background


New concepts in spectrum regulation (pooling, DSA, OSA, auctioning, licensing...)


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Background



Standardization (P1900, 802.22), Conferences


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Background




AAF project: Dynamic Spectrum Access for emergency networks


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Background





Network structure


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Background





Network structure

Functional mapping


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Background





Network structure

Functional mapping

Proposed protocols


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Background





Network structure

Functional mapping

Proposed protocols Channel access


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Background





Network structure

Functional mapping

Proposed protocols Channel access

Directions for the future


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Cognitive Radio: Some History

The point in which wireless personal digital assistants and the related networks

are sufficiently computationally intelligent about radio resources and related

computer-to-computer communications to detect user communications needs

as a function of use context, and to provide radio resources and wire less servicesmost appropriate to those needs

Joseph Mitola III, Cognitive Radio: An Integrated Agent Architecture for Software

Defined Radio, PhD dissertation, Royal Institute of Technology (KTH) Stockholm,

Sweden, 8 May, 2000

Cognitive radio is a paradigm for wireless communication in which either

network or wireless node itself changes particular transmission or reception

parameters to execute its tasks efficiently. This parameter alteration is based on

observations of several factors from external and internal cognitive radio

environment, such as radio frequency spectrum, user behavior, and network state

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


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Some History

Spectrum in 400-1000 MHz range (courtesy: Ir. Marnix Heksamp, measurement: AT)


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New concepts: Spectrum Management

Regulator dependent management

Spectrum Pooling: two or more parties decide how to pool the resurces given by

regulator


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regulator

Spectrum Leasing: lease of spectrum by regulator


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regulator


Spectrum Sharing: giving a chunk of spectrum to set of parties


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regulator



Negotiated Spectrum Use: who can exploit spectrum at particular moment better,

gets it


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regulator




gets it

Regulator independent management

Opportunistic Spectrum Use: use of primary users spectrum such that no

additional interference is introduced


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regulator




gets it

Regulator independent management

Opportunistic Spectrum Use: use of primary users spectrum such that no

additional interference is introduced

Dynamic Spectrum Access: access to licensed channels based on policies ergo itclosely mimics operation of Cognitive Radio


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Standardization, Conferences

P1900.X: IEEE Standard Series on Next Generation Radio and Spectrum

Management

P1900.1: Standard Terms, Definitions and Concepts for Spectrum

Management, Policy Defined Radio, Adaptive Radio and Software DefinedRadio (TU Delft involved in work)


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Management



P1900.2: Recommended Practice for Interference and Coexistence Analysis

(intention to participate by TU Delft)


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Management





P1900.3: Recommended Practice for Conformance Evaluation of SoftwareDefined Radio (SDR) Software Modules


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Management






IEEE 802.22: Standard for a cognitive radio-based PHY/MAC/air interface for use

by license-exempt devices on a non-interfering basis in spectrum allocated to the

TV Broadcast Service (draft by end 2006?)


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Management









FCC: Rules to Permit Unlicensed National Information Infrastructure (U-NII)

devices in the 5 GHz band (comments from TU Delft)


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Management









FCC: Rules to Permit Unlicensed National Information Infrastructure (U-NII)

devices in the 5 GHz band (comments from TU Delft)

IEEE DySPAN, IEEE Crowncom


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Advances in Cognitive Radio: AAF Project

During disaster in Enschede, the Netherlands, in May 2000, where a fireworks

depot exploded and destroyed a large part of the city, killing 23 people and injuring

more than a thousand. Fire brigade, police and relief workers of the medical team

experienced a great deal of communication breakdown, both internally and witheach another.


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The two main factors that caused difficulty in coordinating the teams


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Lack of common standards for each disaster relief group


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experienced a great deal of communication breakdown, both internally and with

each another.



Overloaded emergency frequency bands


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experienced a great deal of communication breakdown, both internally and with

each another.



Overloaded emergency frequency bands In spite of Netherlands having a common radio communication platform for all

emergency services based on TETRA above observation is striking reminder that

one can do better


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AAF Architecture: Network

...

IAN Manager (vehical node,eg. incident command post)

IAN to IAN link

CH to Node link

IAN

Key list IAN Manager (IM) andController (SRM) of allIAN sensing domains

LU device

JAN

EAN

Wired link

IAN

IAN

IAN member and sesingnode (personal node, eg.

first responder)

P. Paweczak, et al. , Dynamic Spectrum Access: An Emergency Network Case Study,

submitted to IEEE Wireless Comm. Mag., 1 July 2006


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AAF Architecture: Node

GSM

UMTS

TETRA

GPS

SDR Platform

AAF

UHF

Emergency

Other

Analog

Frontend

A/D

D/ABaseband Processing RX/TX

Analog

FrontendA/D

data bits

Power / Feature

Measurement

Local

Decision

Global

Decision

FOI

TX/RX

Spectral Analysis System Decision System

FOI: Frequency Occupancy Information

SRM: Spectral Resource Manager

FSS: Frequency Scanning System

BB CTL: Baseband control

Dig. Ch. Sel.: Digital Channel Selection

TX: Transmitter

RXReceiver

Policies

SRM

FOI

Coordination

BB CTL

FSS

Dig. Ch.

Sel..

Channel Selection

Higher protocol Layers

P. Paweczak, et al. , Dynamic Spectrum Access: An Emergency Network Case Study,

submitted to IEEE Wireless Comm. Mag., 1 July 2006


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Spectrum Scanning: A Major Problem

Shadowing: where an individual sensing node may be

blocked by an obstacle, therefore may not be able to

see the Primary User (PU)


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see the Primary User (PU) Multipath fading: where the signals from the PU that

travel different paths may or may not add coherently at

the receiver. As a result, small changes in location

relative to the wavelength of PU impact the Quality of

Detection.


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see the Primary User (PU) Multipath fading: where the signals from the PU that

travel different paths may or may not add coherently at

the receiver. As a result, small changes in location

relative to the wavelength of PU impact the Quality of

Detection.

Solution: Cooperative Scanning


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Spectrum Scanning: Theoretical Result

0 20 40 60 80 1000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

N

Z(N)

tis/tc=0

tis/tc=0.001

tis

/tc

=0.005

tis/tc=0.01

P. Paweczak et al., Performance Measures of Dynamic Spectrum Access Networks,

accepted for publication on IEEE Globecom 2006


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Spectrum Scanning: A Proposed Solution

FOIdataNode1FOIdataNode2

FOIdataNodek

Node IAN Manager

Sensing

FOIdataNode1FOIdataNode2

FOIdataNodek

IAN 1

IAN C

CP

IAN 1 broadcast

CMP

IAN C broadcast

IAN 1 broadcast

IAN C broadcast

P. Paweczak et al., Cluster-Based Spectrum Sensing Architecture for Opportunistic

Spectrum Access Networks, submitted to IEEE Milcom 2006


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Spectrum Scanning: A Proposed Solution

Sensing

phaseIAN 1 IAN C CP

FOI data:

Node1

Nodes to IAN transmission

Data communication

phase

Guard

bandIAN 1 IAN C IAN 1 IAN C

IAN manager to IAN managerbroadcast IAN manager to nodes broadcast

Sensing data frame from IAN nodes

ID FEC

CMP

Combined

data: Nodes1-k

m

ID FEC NJL SNLCAL FECIDFOI data:

Node km

ID FEC

Communiation on CCCCommunication on

LU channels

CAL: Channel Availability ListCP: Contention PhaseCH: Cluster HeadCMP: Cluster Management PhaseFEC: Forward Error CorrectionFOI: Frequency Occupancy InformationNLJ: Newly Joined ListSNL: Scheduled Nodes List




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Spectrum Scanning: some performance results

Plots of probability of scheduling measurement to node non existent in the cluster,

NC=250, R=500, tcp=1 ms, tsl=0.5 ms, v=0.5 m/s.

0 10 20 30 40 500

0.05

0.1

0.15

0.2

0.25

0.3

0.35

P

s

ticf

km=15

km=10

km=5



S S i AAF T b d ( U i i f T )


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Spectrum Scanning: AAF Testbed (courtesy: University of Twente)

Ch l A i t


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Channel Assignment

Because of the PU activity DSA network has to know which channel to use for

communication first

Ch l A i t


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Channel Assignment


communication first

According to our measurements PU activity can be modeled with exponential

distribution (memoryless property)

Channel Assignment


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Channel Assignment


communication first


distribution (memoryless property) Different channel access schemes can be proposed

Channel Assignment


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Channel Assignment


communication first



Network chooses a channel randomly Random (RnD)

Channel Assignment


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Channel Assignment


communication first




Least-used (LeU), when network chooses for new flow channel m with

min(1, . . . , M)

Channel Assignment


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Channel Assignment


communication first




Least-used (LeU), when network chooses for new flow channel m with

min(1, . . . , M) Least-used with Channel Hopping (LeUCH), when network chooses a

channel according to LeU scheme finds out that PU wants to use the it then

tries to choose another channel with the smallest m possible and continue

transmitting rest of the data there.

Channel Assignment: Example of PU Activity


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Channel Assignment: Example of PU Activity

0 1000 2000 3000 4000 5000 6000 7000 80003

4

5

6

7

8

9

10

Measurement number

Signalv

alue

[dBV/m]

Channel Assignment: Simulation Analysis


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Channel Assignment: Simulation Analysis

0 2 4 6 8 100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Load [Erl]

Blocking

probability

M=5 (RND)

M=10 (RND)

M=20 (RND)

M=5 (LU)

M=10 (LU)

M=20 (LU)M=5 (LUCH)

M=10 (LUCH)

M=20 (LUCH)

0 2 4 6 8 100

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Load [Erl]

Blocking

probability

P. Paweczak et al., Performance Measures of Dynamic Spectrum Access Networks,

accepted for publication on IEEE Globecom 2006

Conclusions


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Conclusions

Cognitive Radio is a very fresh research topic

Conclusions


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Conclusions


AAF is probably the first European project strictly related to this issue

Conclusions


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Conclusions



Research community needs to cooperate with policy regulators

Conclusions


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The core of any DSA system is spectrum scanning without physical wideband

scanning devices no implementation is possible

Conclusions


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Work on spectrum scanners is ongoing

Conclusions


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Work on spectrum scanners is ongoing

Proper mathematical models are needed for analysis of DSA systems

Contact Information


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Contact Information

Przemysaw Paweczak, PhD Student

Delft University of Technology

Wireless and Mobile Communications Group

Mekelweg 4, 2628 CD Delft, the Netherlands

Phone: +31 15 27 86697

Fax: +31 15 27 81774

Email: [email protected]

WWW: www.pawelczak.net
http://www.pawelczak.net/http://www.pawelczak.net/

Cognitive Radio From Utopia to Reality by P.pawelczak

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