Cognitive Radio Technology & IEEE802.22 …B1%… · · 2012-03-20Cognitive Radio Technology &...

Cognitive Radio Technology & IEEE802.22 Standardization Activities

Chang-Joo [email protected]

2::: ETRI, The Future Wave ::: 디지털방송연구단

목 차

q CR 기술 개요ü 주파수 자원의 이용현황

ü CR 기술과 전파이용

ü CR 응용

q IEEE802.22 표준 회의ü Functional Requirement

ü Proposal 제안 현황 및 진행 경과

ü Joint Proposal

q향후 일정


무선통신 기술 동향


Definition of Cognitive Radio

▣ Cognitive Radio (NTIA)◈ A Radio or system that senses its operational

electromagnetic environment and can dynamically and autonomously adjust its radio operating parameters to modify system operation, such as maximize throughput, mitigate interference, facilitate interoperability, access secondary markets.


Adaptive radioscan adjust themselves to accommodate anticipated events

Fixed radiosare set by their operators

Cognitive radioscan sense their environment and learn how to adapt

Beyond adaptive radios, cognitive radios can handle unanticipated channels and events.

Cognitive radios require:• Sensing• Adaptation• Learning

Cognitive radios intelligently optimize their own performance in response to user requests and in conformity with FCC rules.

What is a Cognitive Radio?


주파수 분배 및 이용

▣ 한정된 전파자원▣ Spectrum licensing: Exclusive rights▣ Access limited è Throughput limited


주파수 이용 측정

No signals Medium and short duration signals

FCC Should Conduct and

Publish Spectrum Occupancy

Measurements to Identify Low

Occupancy Bands

“In many bands, spectrum access is a more significant problem than physical scarcity of spectrum, in large part due to legacy command-and-control regulation that limits the

ability of potential spectrum users to obtain such access.”— FCC Spectrum Policy Task Force Report


스펙트럼 이용 측정

▣ Some spectrum is intensively used

▣ Other spectrum has highly variable use in when viewed in terms of time and geography


Easement User

2nd-aryUser

2nd-aryUser

Licensee

Not-to-Interfere Basis

Below the Acceptable “Interference Temperature”

CR 기술과 전파이용


Cognitive Radio 개념Cognitive Radio 개념

전파 환경을 측정(Observe) 하고, 그 환경에 적합한 방향(Orient) 을설정, 이 중 최적의 방안을 스스로 결정(Decide)하고, 통신(Act) 하는기술 (OODA Loop): 타 기기에 간섭을 주지 않는 조건

전파 환경을 측정(Observe) 하고, 그 환경에 적합한 방향(Orient) 을설정, 이 중 최적의 방안을 스스로 결정(Decide)하고, 통신(Act) 하는기술 (OODA Loop): 타 기기에 간섭을 주지 않는 조건

User2’ User3


CR의 주파수 이용 개념


Cognition Cycle

Observe

OrientEstablish Priority

Plan

Decide

ActOutsideWorld

Send a Message

Receive a Message

Set Display

Read Buttons Save Global States

Allocate Resources

Initiate Process(es)(Isochronism Is Key)

Generate Alternatives(Program Generation)

Evaluate AlternativesParse

Pre-process

Infer on Context Hierarchy

UrgentImmediate

Normal

Register to Current Time

PriorStates

NewStates

Learn

[Mitola, Ph. D dissertation defense materials, Royal Institute of Technology, 2000]


Cognitive Radio Overview

WidebandA/D-D/A*

Wideband RFConversion

ProgrammableProcessor(s)

Software Radio

J. Mitola : “Software Radio: Technology and Prognosis ”Proc., IEEE National Telesystems Conference 1992“Software Radio Architecture”IEEE Communications Magazine, May 1995Cognitive Radio, Licentiate Thesis,KTH (Royal Institute of Technology), Stockholm

HF LVHF VHF-UHF Cellular Indoor & RF LAN VHDR

2 MHz 28 88 400 960 MHz 6 34 GHz1.39 GHz

PCS

2.5 5.9

Software Radios Very Low Band Low Mid Band High Band

Cellular Mobile

Public Safety

Fixed Terrestrial

4 Channels

Antenna RF ModemINFOSEC

BasebandUser Interface

Model-Based ReasoningRKRL Frames

Spatial &Temporal

Knowledge


Improved Link Reliability

▣ Cognitive radio is aware of areas with a bad signal

▣ Can learn the location of the bad signal◈ Has “insight”

▣ Radio takes action to compensate for loss of signal◈ Actions available:

– Power, bandwidth, coding, channel

◈ Radio learns best course of action from situation

Good Transitional PoorSignal Quality

§ Can aid cellular system§ Inform system & other radios of identified gaps


응용 분야응용 분야

Ø 기존 WLAN 주파수 이용 효율 증대에 CR 기술 이용Ø IEEE 802.11h에서 채널 측정 기능을 포함한 효율적 이용 기술 표준화 중Ø 기존 WLAN 주파수 이용 효율 증대에 CR 기술 이용Ø IEEE 802.11h에서 채널 측정 기능을 포함한 효율적 이용 기술 표준화 중

Ø IEEE 802.22에서 미사용 TV 대역 스펙트럼 이용: CR 기술 표준화 시작(’04년 11월 kick-off 회의, ’05년 1월 Monterey/3월 Atlanta 회의) Ø 응용서비스: 33 km이내 지역까지의 고속 인터넷 서비스, 비 허가 추진

Ø IEEE 802.22에서 미사용 TV 대역 스펙트럼 이용: CR 기술 표준화 시작(’04년 11월 kick-off 회의, ’05년 1월 Monterey/3월 Atlanta 회의) Ø 응용서비스: 33 km이내 지역까지의 고속 인터넷 서비스, 비 허가 추진

WRAN(Wireless Regional Area Network)WRAN(Wireless Regional Area Network)WRAN(Wireless Regional Area Network)

WLANWLANWLAN

ØInterference Temperature Limit 적용: 가능한 대역 활용Ø 비 간섭 조건으로 출력 증가 커버리지 확대, 응용 서비스 다양화

(미국은 기존 출력의 4배까지 허용)

ØInterference Temperature Limit 적용: 가능한 대역 활용Ø 비 간섭 조건으로 출력 증가 커버리지 확대, 응용 서비스 다양화

(미국은 기존 출력의 4배까지 허용)

비 면허 기기비비 면허면허 기기기기

Ø 공공 안전/재난 통신: 평상시 타 목적 이용, 비상시 충분한 채널 확보하여 사용Ø 군용 통신망: 작전이나 해외 파견 시 미 사용 주파수 탐색/활용Ø 이 기종 무선통신망 연동에 응용

Ø 공공 안전/재난 통신: 평상시 타 목적 이용, 비상시 충분한 채널 확보하여 사용Ø 군용 통신망: 작전이나 해외 파견 시 미 사용 주파수 탐색/활용Ø 이 기종 무선통신망 연동에 응용

기 타기기 타타


CMRSPublic SafetyData Services

Data Se

rvice

s

Public Safety

CMRS

1% 10% 100% 10% 1%

1%

10%

100%

Duty Cycle

Use of public safety spectrum is highly variable

Flexible Spectrum Use

ØIllustration: Public Safety & Dynamic Spectrum Use


Challenge Issues


IEEE802.22 표준

q Kick-off meeting(’04.11.)q Interim meeting(’05.1.): Schedule 협의

q Plenary Meeting(’05.3): Functional Requirementsq Interim meeting(’05.9): Call For Proposalq Proposal 접수: ’05.11.

q 9 Proposals

q Merged Proposal: ’06.1q ETRI-FT-I2R-Phillips-Samsung-Thomson

q Runcom/STMicro

q Down-selection Process: ’06.3~


Overview of IEEE 802.22q Scopel 54~862MHz(Unused TV Band)에서 동작하는 Fixed P-MP WRAN(Wireless

Regional Area Network)의 PHY, MAC 규격 정의

q목적lWRAN 시스템의 호환성 확보 및 multivendor화lWireline broadband access에 대한 대체 수단을 제공하여 broadband access

시장 경쟁 촉진l인구 밀도가 낮은 지역을 포함하여 건물이 산재해 있는 지역에 Wireless

broadband access 시스템 시설을 용이하게 함 (dense area는 검토 중)

q Working Group Officersl Chair : Carl R. Stevenson, WK3C Wireless LLC, [email protected])l Vice-Chair : Gerald Chouinard, CRC, [email protected] Secretary : Ashish Pandharipande, Samsung Advanced Institute Of

Technology, [email protected]

q Ad Hoc Groupl General : Gerald Chouinard, CRC, [email protected] MAC : Carlos Cordeiro, Philips, [email protected] PHY : Eli Sofer, Runcom, [email protected]


WRAN 서비스 모델

▣ Framework for developing 802.22 standards


q Provide Broadband Access to one or more core network rather

than forming the end-to-end communication system

o Capability: Similar to ADSL and cable modem over less

propagated rural areas(1.25 person/km2)

o Service Range: typically 33 km, maximum 100 km

o Fixed location customers: geographically fixed, re-locatable, or

nomadic

o Point-to-Multipoint (P-MP) radio interface

o VHF/UHF TV broadcast bands: 41 MHz ~ 910 MHz

o Near- and Non-line-of-sight communication: Due to foliage

q Standardization Target

o 802.22 MAC & PHY between base station and subscribers

(not between base stations)

서비스 모델서비스 모델


Public IP Network

Service Provider IP Network

HAAAA

SD

ACR ACR

WRANBS

CPE

WRAN Hierarchy

•AAA : Authentication, Authorization and Account Server •ACR : Access Control Router HA : Home Agent


WRANRepeater

TV TransmitterWRAN

Base Station

WirelessMIC

WirelessMIC

WRANBase Station

: CPE

: WRAN Base Station

Typical ~33kmMax. 100km

Deployment Scenario


주파수: TV 대역의 CR 전파이용


Adaptive Modulation


Multiple Access TechniquesMultiple Access Techniques

qDuplex Mode

§ Standard must support duplex mode of operation.

§ If FDD is proposed, the proposal must include band plan

or propose a scheme to do it.

qFlexible Asymmetry

§ Internet Access: Most of capacity is consumed in the

downstream direction

§ Surveillance video from CPE: Upstream

§ Telephony and video conferencing: Symmetrical capacity


주요 시스템 변수주요 시스템 변수

q Frequency Range: 41~910 MHz

q Channel Bandwidth: 6, 7, 8 MHz

q Base Station: Transmitter

§ Antenna Gain: 18 dBi

§ Antenna Height: 75 or 150 m HAAT

§ Cable loss: 3 dB

q Base Station: Receiver

§ Antenna Gain & Antenna Height: Same as the transmitter

§ LNA NF: 2.5 dB

§ Interference Allowance: 2 dB

§ Receiver Figure of Merit: -11 dB/K


Coexistence & interference mitigation

-116dBm(6MHz BW) for DTV-107 dBm (200kHz BW)Interference Detection Threshold

100 msec100 msecChannel Closing Transmission Time

(Aggregate transmission time)

2 sec2 secChannel Move Time (In-service

monitoring)

100 msec100 msecChannel Opening Transmission Time (Aggregate transmission time)

2 sec2 secChannel Setup Time

<=2 sec to >=90% PD with False Alarm rate of <=10%

<=2 sec to >=90% PD with False Alarm rate of <=10%

Channel Detection Time

10 minutes (recommended)10 minutes (recommended)Non-Occupancy Period

30 sec (recommended)30 sec (recommended)Channel Availability Check Time

Value for TV BraodcastingValue for Part 74 DevicesDFS Parameters

l DFS Timing requirements


Joint Proposal

◈ ETRI, SEM, GIT◈ Samsung ◈ Phillips, French Telecom◈ I2R◈ Runcom, STMicro◈ NextWave◈ Hawei


System Overview

▣OFDMA both in uplink and downlink▣2K FFT mandatory▣TDD mandatory, FDD optional▣10 msec frame duration ▣16-frame superframe▣QPSK, 16-QAM, and 64-QAM, transformed-QPSK ▣Rate 1/2 through rate 5/6 coding▣30 - 32 sub-channels per TV channel▣Data rate range from 4.8Mbps to 72.6Mbps (with

optional channel bonding and channel aggregation)


Optional fractional use of TV channel and channel bonding up to 3 contiguous TV channels. Channel aggregation of discontiguous channels.

▣ Mandatory: 6, 7, 8 MHzBandwidth

Point-to-Multipoint Network

TDD mandatory

1/4, 1/8, 1/16, 1/32

2K mandatory

Adaptive OFDMA

Default 4W EIRP

QPSK, 16QAM, 64QAM mandatory

▣ Maximum: 4.03 bits/s/Hz▣ Minimum: 0.81 bits/s/Hz

▣ Maximum: 72.6 Mbps▣ Minimum: 4.8 Mbps

Typical range 33 km

54~862 MHz

Specification

Cyclic Prefix Mode

1K / 4K optional, 2K / 4K / 6K for channel bonding FFT Mode

Partial bandwidth allocationMultiple Access

Single TV channel BW of 6 MHzSpectral Efficiency

Service coverage

FDD supportedDuplex

Transmit power

Network topology

Modulation

Maximum of 23 Mbps for 6 MHzData rate

Frequency range

RemarkParameters

System Parameters


Adaptive OFDMA

▣ Flexible Bandwidth Allocation using FFT◈ Channel bonding◈ Fractional bandwidth usage

▣ Adaptive resource allocation according to user environments◈ Channel selectivity


Fractional Bandwidth Usage

• Considering the location, bandwidth and type of the narrowband incumbent users, we can use the fractionally vacant bandwidth of a single channel

• The number of used sub-carriers is proportional to the fractional bandwidth

• If the wireless microphones are operating co-channel, the WRAN systems shall clear the entire channel

• The fractional BW mode is identified by using a Preamble• Example:

6 MHz Unused(6 MHz)6 MHz

f

Incumbent or other CR user(except microphone user)

TV incumbent user Microphone userFractional useof TV channel

GuardBand

Other CR user or non-microphone incumbent (regulations permitting)


Subchannelization

Subcarrier Allocation

AdjacentSubcarrier Permutation


Uniformly DistributedSubcarrier permutationUniformly DistributedSubcarrier permutation

Scattered typeScattered typeBand typeBand type

•Each subchannelconsists of distributed subcarriers within an OFDM symbol

•Only the average CINR over all subcarriers is required

•For users with high frequency selectivity or far distant users

•Each subchannelconsists of a group of adjacent subcarriers

•Bands in good state are selected for data transmission

•Multiuser diversity•Require more feedback

information than distributed subcarrier allocation type

DistributedSubcarrier permutation



frame n-1 frame n frame n+1 ...Time

...

MAC Slot Number

Pre

ambl

e

FCH

DS

-MA

PU

S-M

AP

Se

lf-co

exi

ste

nce

Ranging

UCS Notification

Burst CPE #4

Burst CPE #2

Burst CPE #1

Burst CPE #5

Burst CPE #3

Burst CPE #7

Burst CPE #1

Burst CPE #2

Burst CPE #4

Burst CPE #5

Burst CPE #3

Burst CPE #6

Burst CPE #8

Burst CPE #9

Se

lf-co

exis

ten

ce

Burst CPE #6

Burst CPE #7

Burst CPE #8

TTG

k k+1 k+3 k+5 k+7 k+9 k+11 k+13 k+15 k+17 k+20 k+23 k+26 k+29

TV Channel N

TV Channel N+1

DS US

Log

ica

l MA

C C

han

ne

l Nu

mb

er

s

s+1

s+2

s+L

BW Request

RTG

Frame Structure


Superframe Structure

Superframe n-1 Superframe n Superframe n+1 ...Time

...

Preamble SCH frame 0 frame 1 frame m...

TV Channelt-1

TV Channelt

TV Channelt+1

Time

Preamble SCH

Preamble SCH

Fre

quen

cy

Preamble SCHFrame

0Frame

1

Framem-2

(Quiet)...

... Frame0

Frame1

Preamble SCH

Preamble SCH

Occupied by Incumbent


Framen


Framem

Framem-1


Frame Element Definitions

▣ Preamble – synchronization, channel estimation◈Long training sequence and optional short training

sequence◈There’s also an upstream burst preamble

▣ FCH – frame control header, info on size of DS- and US-MAP and channel descriptors (PHY characteristics)

▣ MAPs – resource scheduling info for user bursts▣ Ranging – timing offset, power adjustment▣ UCS – urgent coexistence situation, incumbent detection

report▣ BW Request – self-explanatory▣ SSS - sliding self-coexistence slots – used by coexistence

beacon to improve coexistence with neighbors ▣ BCH – burst control header for upstream – ID information


Channel Coding

▣ Convolutional Coding (mandatory)◈Rate ½ , other rates by puncturing◈Constraint length 7

▣ Optional Advanced Codes◈Duo-binary Convolutional Turbo Coding (DB-CTC)◈Low-Density Parity Check Coding (LDPC) ◈Shortened block turbo codes (SBTC)


Spectrum Sensing

▣ Proposed methods still remain to be evaluated and compared (Tiger Team)

▣ Several techniques were introduced at previous meetings and have been included in the PHY spec in section 8.8◈Energy detection (full bandwidth or pilot)◈Multi-resolution spectrum sensing and Analog auto correlation◈PN511 or PN63 sequence detection◈Segment sync detector◈Cyclostationary feature detection◈Spectral correlation◈Optimal radiometer

▣ Primary waveforms are DTV and analog FM for wireless microphones◈802.22 TG1 beacon in MAC Section 6.21.1.7.x◈More on this later


Multiple Antenna Options

▣ The following options are under consideration (Sec. 8.10)◈Downlink Closed Loop SDMA◈Adaptive Beam-Forming Techniques◈Space Time Block Coding (STBC)◈Combined Diversity/Spatial multiplexing/Delay

Management


Reference Architecture

Convergence Sublayer / Bridge (e.g., 802.1d)

MAC

PHY

...MAC

PHY

MAC

PHY

Spectrum Manager

Higher Layers: IP, ATM, 1394, etc.

PHY/MAC 1 PHY/MAC 2 PHY/MAC n

Spectrum Manager– facilitates use of non-contiguous channels (channel aggregation)– responsible for maintaining global view of target RF spectrum– assigns spectrum to MAC/PHY modules


Superframe n-1 Superframe n Superframe n+1 ...Time

...

Preamble SCH frame 0 frame 1 frame m...

TV Channelt-1

TV Channelt

TV Channelt+1

Time

Preamble SCH

Preamble SCH

Fre

qu

en

cy

Preamble SCH Frame0

Frame1

Framem-2

(Quiet)...

... Frame0

Frame1

Preamble SCH

Preamble SCH



Framen


Framem

Framem-1

Superframe Structure

Superframe Control Header (SCH)

• TV channels being bonded• Quiet period schedule• Coexistence and superframe information

• Number and size of frames• Information on periodic quiet periods• ID an transmit power of transmitter

•Location configuration information


Protocol Stack Architecture (cont.)

▣ Flexible and scalable channel assignment◈ Implementers decide on the algorithm


MAC View of Frame

frame n-1 frame n frame n+1 ...Time

...

DS PHY PDU

Preamble FCH DS burst 1 DS burst 2 DS burst x...

BcastMsgs

MACPDUs

MAC PDU 1 ... MAC PDU y Pad

MACHeader MAC Payload CRC

DS subframe

Initializationslots

BW requestslots

US PHY PDU(CPE m)

US PHY PDU(CPE p)

...

US subframe

Preamble US burst

MAC PDU 1 ... MAC PDU k Pad

MACHeader MAC Payload CRC

Sliding self-coexistence

slots

Can appear ineither DS or US

BCH

UCSNotification

Slots

PDU – protocol data unit

CRC – cyclic redundancy check

Header – PDU length, connection ID, encryption


Ranging

▣ Downstream management◈ If CPE CINR falls below the range required for the

specified burst profile, the CPE requests transition to a new burst profile

◈See section 6.17.1▣ Upstream management

◈Consists of two procedures:– Initial ranging allows a CPE to join a network and

acquire correct Tx parameters– Periodic ranging allows the CPE to maintain upstream

communications◈For periodic ranging, timers must be maintained for each

channel in DFH operation◈The algorithm is described in section 6.17.2


Distributed Quiet Period▣ When multiple CPEs are operating on different aggregate channels, a hidden node

can result if the CPEs only sense on their active channel▣ Meanwhile the BS is broadcasting on all aggregated channels and interference to

the incumbent results


Distributed Quiet Period▣ This situation can be remedied by distributing the quiet period▣ Each channel is interrupted only once using DQP, while

simultaneous QP would require 3x interruption in this example


Spectrum Sensing


Channel Set

▣ Channel Set: Definitions- Active set 1: a set of used channels for a certain CPE - Active set 2: a set of used channels for a certain BS- Candidate set: a set of clean channels available for a certain CPE

and BS- Occupied set: a set of occupied channels by incumbent user

which a certain CPE finds - Disallowed Set: a set of channels whose access are not allowed

by regulation- Null set : a set of channels that are not classified as one of above

five sets

* Note: The allowed set is defined by union of candidate set and null set depending on channel’s SIR level


Channel Set (cont.)§ Transition diagram for channel set① The channel in null, active or candidate set

becomes a member of occupied set as incumbent user appears.

② Incumbent service releases the channel and its quality is better than an existing member of the candidate set, then it is classified as a member of candidate set.

③ Incumbent service releases the channel and its quality is worse than all member of the candidate set, then it is classified as a member of null set.

④ If the channel quality is better than an existing member of the candidate set, then it replaces the member of candidate set.

⑤ The channel becomes active by new allocation to a WRAN service.

⑥ The poorest channel in candidate set goes to a member of null set as its quality is worse than a new member of candidate set, which comes from null(4), active(7) or occupied(2) sets

⑦ The channel is released due to the termination of its usage and its quality is better than an existing member of the candidate set.

⑧ The channel is classified as a member of null set as the WRAN service releases the channel and its quality is worse than all member of the candidate set.

Null Set

Active Set

Occupied SetCandidate Set1

1

2

75

8

46 13


Sensing Receiver Architecture

MAC

Fine/Feature

RFE

Energy Detection

Omni Antenna

Control


Spectrum Sensing Strategy

Energy Detectionfor wide band

(Analog, RSSI, MRSS, FFT… )

Begin Sensing

Fine/Feature Detection for single channel

End Sensing

occupied?Y

N

MAC(Select

single channel)

FFT CSFDField Sync

OptimumRadiometer

Multi-cycleDetector

AACSpectral

Correlation

Spectrum Usage

Database(BS) ATSC

Segment Sync


향후 일정

Closing

Final Approval/Publication

Submittal to RevCom

Sponsor ballot

WG Draft Standard Process Start

Consolidation/Selection

Functional Requirements 확정 및 Call for ProposalsProposals/Contributions

Editing of Functional Requirements



Draft Functional Requirements

IEEE 802.22 Kick-off meetingWorking Group policy and procedures

주요내용

Denver

Hawaii

Vancouver

Garden Grove, CA

San Francisco

비고

2007. 6.

2008. 12.

2008. 1.

2007. 1.

Interim2006. 1.

Plenary2005. 11.

Interim2005. 9.

Plenary2005. 7.

Interim2005. 5.

Plenary2005. 3

Interim2005. 1.

Plenary2004. 11.

회의종류날짜

IEEE 802.22 표준화 일정IEEE 802.22 IEEE 802.22 표준화표준화 일정일정

Cognitive Radio Technology & IEEE802.22 …B1%… · · 2012-03-20Cognitive Radio Technology &...

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