doc.: ieee 802.22-06/0005r5 submission march 2006 etri, ft, i2r, motorola, philips, samsung,...

March 2006

ETRI, FT, I2R, Motorola, Philips, Samsung, Thomson

Slide 1

doc.: IEEE 802.22-06/0005r5

Submission

A PHY/MAC Proposal for IEEE 802.22 WRAN Systems

IEEE P802.22 Wireless RANs Date: 2006-03-08Authors:

Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.22.Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected].>

Name Company Address Phone Email

John Benko France Telecom (FT) USA [email protected]

Yoon Chae Cheong SAIT Korea +82-31-280-9501 [email protected]

Carlos Cordeiro Philips USA +1-914-945-6091 [email protected]

Wen Gao Thomson Inc. USA +1-609-987-7308 [email protected]

Chang-Joo Kim ETRI Korea +82-42-860-1230 [email protected]

Hak-Sun Kim Samsung Electro-mechanics Korea +82-31-210-3500 [email protected]

Stephen Kuffner Motorola USA +1-847-538-4158 [email protected]

Joy Laskar Georgia Institute of Technology USA +1-404-894-5268 [email protected]

Ying-Chang Liang Institute for Infocomm Research Singapore +65-68748225 [email protected]

March 2006


Slide 2

doc.: IEEE 802.22-06/0005r5

Submission

Co-AuthorsName Company Address Phone email

Myung-Sun Song ETRI Korea +82-42-860-5046 [email protected]

Soon-Ik Jeon ETRI Korea +82-42-860-5947 [email protected]

Gwang-Zeen Ko ETRI Korea +82-42-860-4862 [email protected]

Sung-Hyun Hwang ETRI Korea +82-42-860-1133 [email protected]

Bub-Joo Kang ETRI Korea +82-42-860-5446 [email protected]

Chung Gu Kang ETRI Korea +82-2-3290-3236 [email protected]

KyungHi Chang ETRI Korea +82-32-860-8422 [email protected]

Yun Hee Kim ETRI Korea +82-31-201-3793 [email protected]

Moon Ho Lee ETRI Korea +82-63-270-2463 [email protected]

HyungRae Park ETRI Korea +82-2-300-0143 [email protected]

Martial Bellec France Telecom France +33 2 99 12 48 06 [email protected]

Denis Callonnec France Telecom France +33-4-76-764412 [email protected]

Luis Escobar France Telecom France +33-2-45-294622 [email protected]

Francois Marx France Telecom France +33-4-76-764109 [email protected]

Patrick Pirat France Telecom France +33-2-99-124806 [email protected]

Kyutae LimGeorgia Institute of

TechnologyUSA +1-404-385-6008 ktlim @ece.gatech.edu

Youngsik HurGeorgia Institute of

TechnologyUSA +1-404-385-6008 yshur @ece.gatech.edu

March 2006


Slide 3

doc.: IEEE 802.22-06/0005r5

Submission

Co-AuthorsName Company Address Phone Email

Wing Seng Leon I2R Singapore +65-68748225 [email protected]

Yonghong Zeng I2R Singapore +65-68748225 [email protected]

Changlong Xu I2R Singapore +65-68748225 [email protected]

Ashok Kumar Marath I2R Singapore +65-68748225 [email protected]

Anh Tuan Hoang I2R Singapore +65-68748225 [email protected]

Francois Chin I2R Singapore +65-68748225 [email protected]

Zhongding Lei I2R Singapore +65-68748225 [email protected]

Peng-Yong Kong I2R Singapore +65-68748225 [email protected]

Chee Wei Ang I2R Singapore +65-68748225 [email protected]

Yufei Blankenship Motorola USA +1-847-576-1902 [email protected]

Brian Classon Motorola USA +1-847-576-5675 [email protected]

Fred Vook Motorola USA +1-847-576-7939 [email protected]

Jeff Zhuang Motorola USA +1-847-538-5924 [email protected]

Kevin Baum Motorola USA +1-847-576-1619 [email protected]

Tim Thomas Motorola USA +1-847-538-2586 [email protected]

David Grandblaise Motorola France +33 1 69 35 25 82 [email protected]

March 2006


Slide 4

doc.: IEEE 802.22-06/0005r5

Submission

Co-AuthorsName Company Address Phone email

Dagnachew Birru Philips USA +1-914-945-6401 [email protected]

Kiran Challapali Philips USA +1-914-945-6357 [email protected]

Vasanth Gaddam Philips USA +1-914-945-6424 [email protected]

Monisha Ghosh Philips USA +1-914-945-6415 [email protected]

Gene Turkenich Philips USA +1-914-945-6370 [email protected]

Duckdong Hwang SAIT Korea +82 31 280 9513 [email protected]

Chung Jaehak SAIT Korea +82-32-860-8421 [email protected]

Kim Jaemyeong SAIT Korea +82-32-860-8420 [email protected]

Ashish Pandharipande SAIT Korea +82 010-6335-7784 [email protected]

Yoo Sangjo SAIT Korea +82-32-860-8304 [email protected]

Jeong Suk LeeSamsung Electro-

MechanicsKorea +82-31-210-3217 [email protected]

Chang Ho LeeSamsung Electro-


Wangmyong WooSamsung Electro-


David MazzareseSamsung Electronics Co.

Ltd.Korea +82 10 3279 5210

[email protected]

March 2006


Slide 5

doc.: IEEE 802.22-06/0005r5

Submission

Name Company Address Phone email

Baowei JiSamsung Telecom

AmericaUSA +1-972-761-7167 [email protected]

Max Muterspaugh Thomson Inc. USA +1-317-587-3711 [email protected]

Hang Liu Thomson Inc. USA +1-609-987-7335 [email protected]

Paul Knutson Thomson Inc. USA +1-609-987-7314 [email protected]

Josh Koslov Thomson Inc. USA +1-609-987-7337 [email protected]

Co-Authors

March 2006


Slide 6

doc.: IEEE 802.22-06/0005r5

Submission

Presentation Outline

• PHY Proposal

• Updates to the MAC Proposal

• Conclusions

March 2006


Slide 7

doc.: IEEE 802.22-06/0005r5

Submission


• PHY Proposal


• Conclusions

March 2006


Slide 8

doc.: IEEE 802.22-06/0005r5

Submission

Disclaimer

• The following set of slides represent the joint ETRI-France Telecom-I2R-Motorola-Philips-Samsung-Thomson PHY proposal

• This is in contrast to the MAC presentation, which is confined to describe only the updates

March 2006


Slide 9

doc.: IEEE 802.22-06/0005r5

Submission

PHY Outline• Overview/ Channel bonding

• Fractional Bandwidth

• Sub-Channelization, pilot insertion

• Error Correction Coding

• Multiple antenna

• Sensing

March 2006


Slide 10

doc.: IEEE 802.22-06/0005r5

Submission

PHY Overview

• OFDMA both in uplink and downlink• QPSK, 16-QAM, and 64-QAM, transformed-QPSK • More than 30 sub channels per TV channel• Contiguous channel bonding upto 3 TV channels (and

beyond in a stack manner)• Data rate range from 5Mbps to 70Mbps• TDD, FDD

RandomizerModulation(constellationmapping)

InterleaverFEC

March 2006


Slide 11

doc.: IEEE 802.22-06/0005r5

Submission

What We Have Proposed ….

• Adaptively scalable to spectrum availability• Channel Bonding • New frame structure for CR-enabled operation• Enhanced PHY features - Adaptive sub-carrier allocation - Adaptive pilot insertion - Enhanced channel coding (LDPC, Turbo Code,

SBTC) - Multiple antenna options

Known and proven technology

for broadband fixed/mobile wireless access

(e.g., IEEE 802.16d/e – WiBro in Korea)

AdaptiveOFDMA

March 2006


Slide 12

doc.: IEEE 802.22-06/0005r5

Submission

Advantages of Adaptive OFDMA Proposal

• Flexible Bandwidth Allocation– To use the partial bandwidth (1, 2, 3, 4, 5, 6, 7, 8 MHz) adaptively,

depending on the channel state information (availability)

– To fully utilize available bandwidth under a unified PHY framework

• Single Sampling Frequency– Sampling frequency is the same for all FFT modes.

• Constant Subcarrier Spacing– The subcarrier spacing is constant for all different channel

bandwidths Robust to the frequency offset

March 2006


Slide 13

doc.: IEEE 802.22-06/0005r5

Submission

PHY (Baseband) Architecture

RandomizerEncoderPuncturer

&Interleaver

MapperSubcarrierAllocator

S/ P

Preamble&

PilotInsertion

IFFTGuard

InsertionP/ S

AWGN

Channel

De-randomizer

Decoder

De-interleaver

&Depuncturer

De-mapper

SubcarrierDeallocator

P/ SChannel

EstimationFFT

GuardRemoval

S/ P

Synchronization

BinaryData

RecoveredData

March 2006


Slide 14

doc.: IEEE 802.22-06/0005r5

Submission

System Parameters: ProposedParameters Specification Remark

Frequency range 54~862 MHz

Service coverage Typical range 33 km,

Bandwidth• Mandatory: 6, 7, 8 MHz with channel bonding• Optional: fraction BW

Allows the fractional use of TV channel and channel bonding up to 3 TV channels

Data rate• Maximum: 70 Mbps• Minimum: 4.5 Mbps

Maximum of 23 Mbps for 6 MHz

Spectral Efficiency• Maximum: 3.94 bits/s/Hz• Minimum: 0.75 bits/s/Hz

Single TV channel BW of 6 MHz

Modulation QPSK, 16QAM, 64QAM

Transmit power Default 4W EIRP

Multiple Access Adaptive OFDMA Partial bandwidth allocation

FFT Mode 1024, 2048, 4096, 6144

Cyclic Prefix Mode 1/4, 1/8, 1/16, 1/32

Duplex TDD or FDD

Network topology Point-to-Multipoint Network

March 2006


Slide 15

doc.: IEEE 802.22-06/0005r5

Submission

Channel Bonding: Motivation

• Spectrum occupancy measurements conducted by Shared Spectrum Company from January/2004 to August/2005 have shown that:

• “There is a significant amount of spectrum available in continuous blocks that are 1 MHz and wider ”

• “A dynamic spectrum sharing radio with a low agility, contiguous waveform will provide high utility”

• The November 18, 2005, study from Freepress and New America Foundation (entitled “Measuring the TV “White Space” Available for Unlicensed Use”) reveals that there exists a considerable amount of contiguous vacant TV channels (especially in the upper UHF band)

• More can be expected in other countries

March 2006


Slide 16

doc.: IEEE 802.22-06/0005r5

Submission

Contiguous open spectrum available!

Example: Jackson, Mississippi

Source: “Measuring the TV ‘White Space’ Available for Unlicensed Wireless Broadband”, Nov 18, 2005, New America Foundation

March 2006


Slide 17

doc.: IEEE 802.22-06/0005r5

Submission

Channel Bonding

• Make opportunistic and simultaneous use of multiple contiguous TV channels

• Benefits:– More data rate or range

• Initial link-budget analysis showed that single-TV channel can not support full data rate (e.g., 18Mbps) upto 30 Km range

– Multi-path Diversity• Small BW signal can have deep fade or flat fade

• Wider-bandwidth signal provides more frequency/multipath diversity

– Interference• Wider-band reduces the amount of interference

March 2006


Slide 18

doc.: IEEE 802.22-06/0005r5

Submission

Channel Bonding: Capacity

• Aggregate TV channels to get more capacity– Shannon: C = B.log2(1+S/N)

– capacity proportional to BW, but logarithmic with SNR or signal power

• If S/N is fixed, then capacity increases linearly with bandwidth

• If signal power is fixed, but bandwidth is increased– C = B.log2(1+S/(BNo))

– Capacity still increases as bandwidth is increased

March 2006


Slide 19

doc.: IEEE 802.22-06/0005r5

Submission

Capacity of aggregated channels as a given signal power is spread over more channels

March 2006


Slide 20

doc.: IEEE 802.22-06/0005r5

Submission

Preliminary Link Budget (LOS)

modulation QPSK 64-QAM 16-QAMcoding rate 1/2 2/3 1/2Throughput/channel 5 19 29 Mb/scenter frequency 0.7 0.7 0.7 GHzbandwidth 6 6 18 MHzDistance 30000 6000 30000 mTx power 4 4 4 WTx averg power 36.0 36.0 36.0 dBmTX antenna gain 0.0 0.0 0.0 dBiRx powerfree space path loss 119 105 119 dBRx antenna gain 12 12 12 dBicable and other losses 3 3 3 dBTotal received avrg power -74 -60 -74 dBmReceiver noise figure 4 4 4 dBNoise power -106 -106 -101 dBmInterference allowance 3 3 3 dBReceived SNR 25 39 21 dBRequired SNR 4 25 10 dBImplementation/OFDM loss 6.0 6.0 6.0 dBLink Margin 15.4 8.3 4.6 dB

• Difficult to achieve 19Mbps over 30Km

• channel bonding needed to achieve long range

March 2006


Slide 21

doc.: IEEE 802.22-06/0005r5

Submission

Channel Bonding Scheme

• 6, 12, 18 MHz channels

• Constant inter-carrier spacing

• Depends on availability

• Several receiver techniques to deal with flexible BW– Selectable analog filters

– Up sampling digital filters

TVTV

WRAN

N N+1 N+2N-1N-2 N+4N+3N-3

TVTV

WRAN

N N+1 N+2N-1N-2 N+4N+3N-3

TVTV

WAN

N N+1 N+2N-1N-2 N+4N+3N-3

March 2006


Slide 22

doc.: IEEE 802.22-06/0005r5

Submission

Channel bonding structure

• 6K FFT over 3 TV channels– 2K per TV channel

– Null out the outer carriers for 1 or 2 TV channels

• Fixed inter-carrier spacing– Several implementation

possibilities

DataSub-carrier

PilotSub-carrier

Guard/NullSub-carrier

6 MHz

18 MHz

12 MHz

DC

DC

DC

12 MHz

6 MHz

18 MHz

March 2006


Slide 23

doc.: IEEE 802.22-06/0005r5

Submission

FFT Mode for WRAN Systems

No. of Bonded Channel

Basic FFT Mode

1 2 3

1K 1K 2K NA

2K 2K 4K 6K

4K 4K NA NA

6K 6K NA NA

March 2006


Slide 24

doc.: IEEE 802.22-06/0005r5

Submission

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

qu

en

cy

Preamble SCHFrame

0Frame

1

Framem-2

(Quiet)...

... Frame0

Frame1

Preamble SCH

Preamble SCH

Occupied by Incumbent


Framen


Framem

Framem-1

March 2006


Slide 25

doc.: IEEE 802.22-06/0005r5

Submission

Preamble

• Superframe preamble – Over 1512 sub-carriers (every fourth or second non-zero),

– 5 MHz BW

– Simply duplicate for additional TV channels

– 1 MHz gap between adjacent channels to relax filtering

– 2 symbol duration (1 more for data)

• Frame preamble: 1-3 TV channels – 1728*N sub-carriers

– Short preamble is optional

ST1 ST5ST4ST3ST2 LT1 LT2GI

TSYMTSYM

(short) (long)

Example structure

March 2006


Slide 26

doc.: IEEE 802.22-06/0005r5

Submission

Preamble

• Preamble has the repetition pattern in the time domain:

– Time synchronization

– Frequency synchronization

– Channel estimation

– Cell ID detection

• Preamble is modulated using BPSK modulation.

March 2006


Slide 27

doc.: IEEE 802.22-06/0005r5

Submission

Transformed QPSK/OFDMA

• Spread data over some sub-carriers (QPSK only)– Hadamard– Two-carrier– FFT based unitary pre-coding– Frequency offset DFT

• Depending on the receiver structure, this can– Increase capturing of multipath

diversity– Increase resiliency

to interferers• Receiver structures

– MMSE– Approximate ML

dev 1(64QAM)

dev3

dev5 (16QAM)

Dev4 (S-QPSK)

Dev2 (16QAM)

Dev7 (S-QPSK)dev6 (64QAM)

Dev8(64QAM)

1234

Time (in OFDM symbol unit)

subchannels

March 2006


Slide 28

doc.: IEEE 802.22-06/0005r5

Submission

OFDMA Parameters/Single Channel (6MHz)

Mode 1K 2K 4K 6K

FFT Size 1024 2048 4096 6144

Bandwidth(k = 1, 2, …, 6)

k MHz

Sampling Factor 8/7

No. of Used Subcarriers(including pilot, but not DC)

140 * k 280 * k 560 * k 840 * k

Sampling Frequency 48/7 MHz

Subcarrier Spacing 6.696 kHz(***) 3.348 kHz 1.674 kHz 1.116 kHz

Occupied Bandwidth 6.696 kHz*140*k 3.348 kHz*280*k 1.674 kHz*560*k 1.116 kHz*840*k

Bandwidth Efficiency(*) 93~94 %

FFT Time 149.33 us 298.66 us 597.33 us 896 us

Cyclic Prefix Time(**) 37.33 us 74.66 us 149.33 us 224 us

OFDMA Symbol Time 186.66 us 373.33 us 746.66 us 1120 us

(*) Bandwidth Efficiency = Subcarrier Spacing * (Number of Used Subcarriers + 1)/BW(**) It is assumed that cyclic prefix mode is 1/4.(***) Italics indicate an approximated value.

March 2006


Slide 31

doc.: IEEE 802.22-06/0005r5

Submission

OFDMA parameters – channel bonding

Parameter3 TV bands 2 TV bands 1 TV bands

18 21 24 12 14 16 6 7 8

Inter-carrier spacing,

F (Hz)3348 3906 4464 3348 3906 4464 3348 3906 4464

FFT period, TFFT (s) 298.66 256.00 224.00 298.66 256.00 224.00 298.66 256.00 224.00

Total no. of sub-carriers,

NFFT

6144 4096 2048

No. of guard sub-carriers,

NG (L, DC, R)1104 (552,1,551) 736 (368,1,367) 368 (184,1,183)

No. of used sub-carriers,

NT = ND + NP

5040 3360 1680

No. of data sub-carriers, ND 4680 3120 1560

No. of pilot sub-carriers, NP 360 240 120

Occupied bandwidth (MHz) 16.884 19.698 22.512 11.256 13.132 15.008 5.628 6.566 7.504

Bandwidth Efficiency (%) 93.8

March 2006


Slide 32

doc.: IEEE 802.22-06/0005r5

Submission

Data Rate• Bandwidth = 6 MHz

• FFT size = 2048

• Cyclic prefix mode = 1/4

• No pilot, no quiet periods assumed

Code Rate

Modulation7/8 5/6 3/4 2/3 1/2

64QAM 23.63 22.50 20.25 18.00 13.50

16QAM 15.75 15.00 13.50 12.00 9.00

QPSK 7.88 7.50 6.75 6.00 4.50

Unit: Mbps

Data Rate = No. of used subcarriers * code rate * no. of bits per modulation symbol/OFDM symbol time

March 2006


Slide 33

doc.: IEEE 802.22-06/0005r5

Submission

Data Rate – Channel Bonding• Bandwidth = 3*6 MHz

• FFT size = 2048



Code Rate

Modulation7/8 5/6 3/4 2/3 1/2

64QAM 70.89 67.50 60.75 54.00 40.50

16QAM 47.25 45.00 40.50 36.00 27.00

QPSK 23.64 22.50 20.25 18.00 13.50

Unit: Mbps

Data Rate = No. of used subcarriers * code rate * no. of bits per modulation symbol/OFDM symbol time

* no. of channel bonded

March 2006


Slide 34

doc.: IEEE 802.22-06/0005r5

Submission

Spectral Efficiency

Code Rate

Modulation7/8 5/6 3/4 2/3 1/2

64QAM 3.94 3.75 3.38 3.00 2.25

16QAM 2.63 2.50 2.25 2.00 1.50

QPSK 1.31 1.25 1.13 1.00 0.75

Unit : bps/Hz

Spectral Efficiency = No. of used subcarrier*code rate*no. of bits per modulation symbol/OFDM symbol time/BW

• Single channel bandwidth = 6 MHz

• FFT size = 2048



• The spectral efficiency is same for all fractional BW mode

March 2006


Slide 35

doc.: IEEE 802.22-06/0005r5

Submission

Minimum Peak Throughput per CPE

Code Rate

Modulation7/8 5/6 3/4 2/3 1/2

64QAM 2.15 2.05 1.84 1.64 1.23

16QAM 1.43 1.36 1.23 1.09 0.82

QPSK 0.72 0.68 0.61 0.55 0.41

Unit : Mbps

Min. Peak Throughput = No. of used subcarriers*code rate*no. of bits per modulation symbol/OFDM symbol time/no. of CPE’s

• Bandwidth = 6 MHz• FFT size = 2048• Cyclic prefix mode = 1/4• No. of CPE’s = 512 CPE’s/oversubscription ratio 50 ~ 11 CPE’s• No pilot, no quiet periods assumed

March 2006


Slide 36

doc.: IEEE 802.22-06/0005r5

Submission

Fractional BW Usage

March 2006


Slide 37

doc.: IEEE 802.22-06/0005r5

Submission

Fractional Bandwidth Usage

• If wireless microphones are in operation in TV channel, the WRAN systems may be clear the entire TV channel

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

• 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 channel Microphone user

Fractional useof TV channel

March 2006


Slide 38

doc.: IEEE 802.22-06/0005r5

Submission

Fractional Bandwidth Mode

• Total Number of Fractional BW Mode To Detect : 36

1 2 3 4 5 6 7 8

1

2

3

4

5

6

7

8

Start position of fractional BW mode

Fra

ctio

nal

BW

12345678

Fra

ctio

nal B

W o

f 1

MH

z

Null

Null

Real B

W o

f 8

MH

z

Start positionof fractional BW mode

Fractional BWmode zone

Not applicable

March 2006


Slide 39

doc.: IEEE 802.22-06/0005r5

Submission

Preamble Sequence for Fractional BW Usage (2K FFT)

Index Fractional BW Start Position PN Sequence (1680 bits)

0 1 0

0x251D994101EDA04D8BD0B8EA6FA20AE590C2CC199AB083C6AE61F091F2DD41D989EC164B1481D611BE9CEA0094AFE9DB56A4763F55B26E54EAB73ACD7D4BBA64C1421BC3EB9D67113A5FB9C529AADC9CAB1FB882905601778659CDB69AFCBADDF8B42314A7985B5F87C20692309D350454FF9326481683FADAE4711DD0CC5DACEDF7CD5DF1177D60EBA4DBE657F19F08189EFC6B5DE6C2CFDCD13195DE077586B8EE01E00B6468B10A53FAAC1DD846E2A01681980D444B6AD0D34C34EC9CFD9341507878EC9FBAE498F5A20614BDF3E4B22D

1 1 1

2 1 2

3 1 3

4 1 4

5 1 5

6 1 6

7 1 7

8 2 0

9 2 1

10 2 2

11 2 3

12 2 4

13 2 5

14 2 6

… … … …

33 7 1

34 7 2

35 8 1

This sequence will be determined to minimize

the PAPR

March 2006


Slide 40

doc.: IEEE 802.22-06/0005r5

Submission

Flow Diagram of Fractional BW Mode Detection

CPE Power On Fractional BW ModeDetection

Using Preamble

Decoding SuperframeControl Header (SCH)

Fractional BWUsage Mode

Decoding Frame

Synchronization &Channel Estimation

Superframe PreambleStart Position Detection

Signal Detection &Automatic Gain Control

Channel Bonding

Information

March 2006


Slide 41

doc.: IEEE 802.22-06/0005r5

Submission

Simple Mode Detection Procedure (1)

CPEPower On

Searchthe Fractional BW

Usage Mode(Correlation with

All PreambleSequence)

Confirmthe Fractional BW

Usage Mode(Correlation with

Previous PreambleSequence)

CorrelationOut>TH?YES

NO

March 2006


Slide 42

doc.: IEEE 802.22-06/0005r5

Submission

Simple Mode Detection Procedure (2)

• Example:

TransmittedSuperPreamble

Index

CorrelatedSuperPreamble

Index

DetectedSuperPreamble

Index

0 0 … 0 17 17 … 17 31 31 … 31 25 25 …

All 0 … 0 0 17 … 17 17 31 … 31 31 25 …

0 0 … 0 17 17 … 17 31 31 … 31 25 25 …

The Correlation Out is less than the Threshold

Search all fractional mode again

Fractional mode changed

March 2006


Slide 43

doc.: IEEE 802.22-06/0005r5

Submission

Subchannelization

March 2006


Slide 44

doc.: IEEE 802.22-06/0005r5

Submission

Symbol Structure For AMC/Diversity Subchannel

• The concept of AMC subchannel is same to that of 802.16-2004

• The concept Diversity subchannel is same to the DL optional FUSC of 802.16-2004

• Just the number of used subcarriers is different

– 802.16e: no. of subchanel=32, no. of subcarriers per subchannel=54

– 802.22: no. of subchanel=30, no. of subcarriers per subchannel=56

• So the basic permutation sequence will be slightly modified

March 2006


Slide 45

doc.: IEEE 802.22-06/0005r5

Submission

Pilot Pattern Design (1)

• Pilot pattern is varied with channel condition

• Pilot pattern is controlled by adjusting the pilot symbol interval and pilot subcarrier interval

• A robust channel parameter estimation is required for reliable pilot design

March 2006


Slide 46

doc.: IEEE 802.22-06/0005r5

Submission

Pilot Pattern Design (2)• RMS delay spread of WRAN profile (Approximated)

• Pilot subcarrier interval can be determined as follows– Pilot subcarrier interval*subcarrier spacing < coherent bandwidth

Multipath ProfileParameters A B C D

CoherentBandwidth

(kHz)

90% 28.90 23.61 18.63 3.38

50% 289.02 236.13 186.39 33.80Pilot

SubcarrierInterval

90% 8.63 7.05 5.56 1.00

50% 86.32 70.52 55.67 10.09

1) We assume that the BW is 6 MHz and FFT mode is 2K.2) 90% coherent BW=1/(50*rms delay spread), 50% coherent BW=1/(5*rms delay spread)

Multipath Profile A B C D

RMS Delay Spread 692 ns 847 ns 1073 ns 5917 ns (*)

(*) We assume that the 6-th path has the excess delay of 60 ns and relative amplitude of -10 dB

March 2006


Slide 47

doc.: IEEE 802.22-06/0005r5

Submission

Pilot Pattern Design (3)• Coherent Time

– 1/fm, where, fm is the maximum doppler shift

• Pilot symbol interval can be determined as follows– Pilot symbol interval*OFDMA symbol time < coherent time

Multipath ProfileParameters A B C D

Maximum Doppler Shift (Hz) 2.5

Coherent Time (sec) 0.4

Pilot Symbol Interval 1071.4

Here, we assume that the BW is 6 MHz, FFT mode is 2K, and GI mode is 1/4.

March 2006


Slide 48

doc.: IEEE 802.22-06/0005r5

Submission

Pilot Pattern For AMC Subchannel

• Typical BIN structure– Set of 14 contiguous subcarriers within an OFDMA symbol

• AMC subchannel consists of 4 contiguous bins

12 Data Subcarriers

2 Pilot Subcarriers

March 2006


Slide 49

doc.: IEEE 802.22-06/0005r5

Submission

Pilot Pattern For Diversity Subchannel

• All the pilot subcarriers are allocated first• And then the remaining subcarriers are used

exclusively for data transmission• Number of used subcarriers are divided into 14

contiguous subcarriers in which two pilot subcarriers are allocated

• The position of the pilot subcarriers in 14 contiguous subcarriers varies according to the index of OFDMA symbol which contains the subcarriers

• Pilot subcarrier index:– k : pilot subcarrier index, 0,…,239 for 2K mode– m : [symbol index] mod 3

137 mk

March 2006


Slide 50

doc.: IEEE 802.22-06/0005r5

Submission

Advanced Channel Coding

March 2006


Slide 51

doc.: IEEE 802.22-06/0005r5

Submission

Channel Coding

• Coding Scheme– Mandatory: Convolutional Code -> similar to 802.16

– Optional:• Duo Binary Turbo Code

• LDPC Code (IEEE 802.16e LDPC) New

• Shortened block turbo code New

– Optional advanced codes currently undergoing cross-simulations• Will compare results and select best optional code(s)

• Selected Code Rates– R = 1/2, 2/3, 3/4, 5/6

March 2006


Slide 52

doc.: IEEE 802.22-06/0005r5

Submission

Duo-Binary Turbo-Code Summary

• Excellent performance for wide range of blocks– Have optimized parameters for blocks from 6 bytes to 240 bytes

• Highly flexible scheme– Same encoder/decoder for all blocksizes/coding rates

• Reasonable complexity– ~35% decrease in complexity/decoded bit compared to Binary TC.

• Mature Technology

• Code Reuse/ Already in following standards– IEEE 802.16 / WiMAX; HomePlug, DVB-RCS, DVB-RCT,

ETSI HIPERMAN

March 2006


Slide 53

doc.: IEEE 802.22-06/0005r5

Submission

Low-Density Parity-Check Codes

• Motivation for LDPC– Near capacity performance

– High-throughput low-complexity implementation

– Code reuse between 802 specifications

• Features of IEEE 802.16e LDPC codes– Compact representation of code matrices

– Simplified structured encoder/decoder architecture across all code rates

– Low-complexity differential-style encoding

– Enhanced Layered Decoding to reduce the number of iterations

– Special design feature in rate 1/2, 2/3 code provides further throughput doubling in layered decoding

March 2006


Slide 54

doc.: IEEE 802.22-06/0005r5

Submission

LDPC Code Reuse Within 802• LDPC codes adopted in DVB-S2, 802.16e, 802.11n• IEEE 802.16

– Initial WiMax profile includes• CC and CTC, Chase Combining HARQ for CTC

– Future WiMAX profiles likely to include…• CTC with incremental redundancy (IR) HARQ

– IR may add little value for fixed access

• LDPC with Chase Combining– Missed first profile due to time-to-market considerations

• IEEE 802.11n– IEEE 802.16e-style LDPC codec adopted as the only

advanced channel coding scheme in January 2006 joint proposal

• Selecting LDPC for 802.22 would lead to additional reuse

to/from indoor

antenna

802.22 radio

802.11n radio

Common baseband elements

to/from rooftop antenna

ethernet

March 2006


Slide 55

doc.: IEEE 802.22-06/0005r5

Submission

Shortened Block Turbo Code (SBTC)

• Turbo product code (TPC) is an advanced coding option in 802.16

• STBC is an improved form of TPC– SBTC has lower decoding complexity than TPC without

performance loss

• Component code – Extended Hamming code

• Native code: (16,11), (32,26) and (64,57)• Other code rate through shortening

– Parity check code• (8,7) and (16,15)

March 2006


Slide 56

doc.: IEEE 802.22-06/0005r5

Submission

Parity Check Matrices for Hamming Codes

154111000

111000

110110

101101

315111000

111000

111000

110110

101101

636111000

111000

111000

111000

110110

101101

N’ = 15K’ = 11

N’ = 31K’ = 26 N’ = 63

K’ = 57

Special parity check matrix design simplifies the decoding complexity.The syndrome value gives the error position, thus, look-up table is not needed.

March 2006


Slide 57

doc.: IEEE 802.22-06/0005r5

Submission

Multiple Antennae Options

March 2006


Slide 58

doc.: IEEE 802.22-06/0005r5

Submission

Multiple Antenna Options

– Equal Gain Transmit Beamforming Using Codebooks.

– Downlink Closed Loop SDMA.

– Adaptive Beam-Forming Techniques.

– Space Time Block Coding (STBC).

– Combined Diversity/Spatial multiplexing/Delay Management.

– Uplink “Virtual” SDMA MIMO.

Multiple antennae techniques offer various advantages in various scenarios, including inherent benefits for the protection of incumbents. We are studying the following options. Final decisions on which ones are included will be based on performance and complexity.

March 2006


Slide 59

doc.: IEEE 802.22-06/0005r5

Submission

Equal Gain Transmit Beamforming

• When multiple antennae are used for transmission, it is very important to have equal gain transmissions from each antenna, especially when used with OFDM.

• Eigen-beamforming, when used in an asymmetrical situation (NT > NR), DOES NOT guarantee equal power.

• Single-stream or multiple stream transmission is proposed

March 2006


Slide 60

doc.: IEEE 802.22-06/0005r5

Submission

Quantized Equal Gain Beamformer For Single Stream

• NT transmit antennae and NR receive antennae (NR could be 1).• Objective: find quantized beamformer Q (NT X 1).• Method:

– All entries of Q are restricted to be – First entry is fixed at 1+ j– Q is picked to maximize– No. of bits required to specify Q: 2*(NT -1) per frequency bin.– If p consecutive frequencies are grouped, Q is picked to maximize

– e.g: 2x1 beamformer, grouping 4 tones over 64 tones bandwidth would require only 4 bytes of feedback, with ~ 1dB degradation.

• Multiple streams: find multiple beamformers of that form for the simultaneous transmission of multiple streams to 1 user

j1

QHHQ HH

iiHi

Hi

p

iQHHQ

1

March 2006


Slide 61

doc.: IEEE 802.22-06/0005r5

Submission

Quantized Equal Gain BeamformerPerformance Summary

• Performance summary was presented in January 2006 [doc.: IEEE 802.22-06/0005r1]

• Very simple and efficient codebook based beamforming, ensuring equal gain transmissions.

• About 6 –7dB downlink gain with 2 transmit antennae.• About 11-12dB downlink gain with 4 transmit antennae.

• Similar gains on uplink, with receive-diversity at base-station.

• Gains can be realized with about 4 bytes of feedback per user for 2 transmit antennae and 12 bytes per user for 4 transmit antennae.

• CPE could have more receive antenna than transmit antennae, for added performance, without changing the feedback requirements.

March 2006


Slide 62

doc.: IEEE 802.22-06/0005r5

Submission

Downlink Closed-Loop SDMA (CL-SDMA)Linear processing with downlink channel sounding

• Throughput performance was presented in January 2006 [doc.: IEEE 802.22-06/0016r1]

• Very large throughput can be achieved by the use of reliable channel state information at the transmitter in slowly fading channels, to allow for coordinated beamforming between the transmitter and the receivers

• Practical implementation:– In FDD or TDD: CL-SDMA Mode 1 (2 base station antennas)

No channel reciprocity requirement: finite-rate quantized feeedback– In TDD: CL-SDMA Mode 2 (2 or more base station antennas)

Requires channel reciprocity: direct uplink sounding

• Use on adjacent permutation subcarriers with multiuser diversity

March 2006


Slide 63

doc.: IEEE 802.22-06/0005r5

Submission

CL SDMA Overview

The Base Station has N transmit antennas, and uses N beamforming vectors M1 … MN

CPEs have N or more receive antennas, and use beamforming vectors W1 , W2 … WN

CL SDMA Mode 1 is only applicable with N = 2 transmit antennas.

xk

x1

xN

W1*

x1 estimate

Wk*

xk estimate

WN*

xN estimate

Base station transmitter

downlinktransmission

M1

Mk

MN

1

2

k

N

CPE receivers

March 2006


Slide 64

doc.: IEEE 802.22-06/0005r5

Submission

Base Station Transmitter and CPE Receiver Structures

Channel Encoder

QAM Modulation X

X +

+

OFDMModulation 1

Channel Encoder

QAM Modulation X

XOFDM

Modulation 2

User 1Data Packet

User 2Data Packet

M1,1

M1,2

M2,1

M2,2

1

2

OFDMDemodulationX

+

W*k,1

OFDMDemodulationX

W*k,2

NOFDM

DemodulationX

W*k,N

Channel Decoder

User k decodedData Packet

MMSE or ZF per tone

QAM demodulator

Receiver or user k

March 2006


Slide 65

doc.: IEEE 802.22-06/0005r5

Submission

Adaptive Beam-Forming

• Adaptive beam-forming (ABF) for 802.22 systems:

– Mitigate co-channel interference (CCI) inherent to OFDMA systems

– Since all CPEs are fixed at known locations, their directions-of- arrival (DOAs) may easily be obtained at the BS.

– Large cell in 802.22 networks also makes beam-forming problem simple from 2D to 1D problem: easy DOA estimation.

– With the transmit and/or receive diversity, adaptive beam-forming may significantly increase the cell radius.

• More efficient than fixed-beam array

March 2006


Slide 66

doc.: IEEE 802.22-06/0005r5

Submission

Adaptive Beam-Forming Algorithms

• DOA Based Sample Matrix Inversion (SMI) Algorithm

where is the steering vector for incident angle and is the estimated interference-plus-noise covariance matrix.

• Reference Signal Based SMI Algorithm

where is the correlation vector and is the estimated covariance matrix.

– Reference signal is required!

1ˆˆ u w R a

a

1ˆ ˆˆ x xdw R r

ˆuR

ˆxRˆxdr

March 2006


Slide 67

doc.: IEEE 802.22-06/0005r5

Submission

Adaptive Beam-FormingPerformance Summary


• Efficient CCI cancellation by simple adaptive beam-forming algorithms

• In uplink, the reference signal method seems more effective due to

– Simplicity in implementation

– Robustness to calibration errors due to self-healing nature

– However, in case of a very large delay spread, the DOA based approach seems preferable.

– Selective usage according to environments may be necessary.

• In downlink, the DOA based adaptive beam-forming seems more desirable.

– Robustness to calibration errors in downlink

March 2006


Slide 68

doc.: IEEE 802.22-06/0005r5

Submission

Figure. Block diagram of an STBC-OFDM system

Cyclic prefix

RemovalFFT P/S

Linear Combiner

Data demapping

Binary output data

Data mapping

S/P STBCEncoding

IFFT

IFFT

Cyclic prefix

Cyclic prefix

Binary input data

1~ 4h

General STBC

March 2006


Slide 69

doc.: IEEE 802.22-06/0005r5

Submission

STBCPerformance Summary


• 2K FFT OFDMA, 2 OFDM symbols preamble, and channel estimation– Partitioned MMSE estimation performed by using the preamble– SNR in MMSE: 20dB– RMS delay parameter in MMSE: 9s

• About 3 –7dB downlink gain for =0.7, when employing (2 x 1) STBC scheme.

• Additional ~2.5dB gain when employing (2 x 1) closed loop transmit diversity.

• Even in a highly correlated case, for example =0.9, the performance improvement is rather significant.

March 2006


Slide 70

doc.: IEEE 802.22-06/0005r5

Submission

Full Diversity Full Rate Scheme

• While Space-Time Coding (STC) aims for transmit diversity gain, Spatial Multiplexing (SM) increases the throughput in MIMO channels.

• Full Diversity Full Rate (FDFR) schemes strike both the diversity and multiplexing at the same time.

• In FDFR, complexity at the receiver is much higher than SM.

• We propose a scheme, which facilitates successive interference cancellation at the receiver with slight loss in rate.

• Thus, the proposed scheme is FD but almost FR.

March 2006


Slide 71

doc.: IEEE 802.22-06/0005r5

Submission

Basic Transmit Beamforming (BTB)

• In DL, beamformer only directs transmission to the path/cluster with the strongest gain per user.

• Other directions are suppressed – reducing overall delay

• Frequency domain beamforming for each user (subchannel) – different directions

.

.

.

Ant NT

Ant 1

.

.

.

User K

User 1

MOD Frequency Domain

Beamformer

MOD

Frequency Domain

Beamformer

Windowing & Pulse Shaping

OFDMA Formulator

OFDMA Formulator


March 2006


Slide 72

doc.: IEEE 802.22-06/0005r5

Submission

Transmit Beamforming with Diversity/Spatial Multiplexing

• In DL, beamformers direct transmission several pathss/cluster

• Uncorrelated eigen-channels may be used for diversity transmission (CDD) or spatial multiplexing.

.

.

.

Ant NT

.

.

.

Ant 1

Channel Coded Bits of User 1

MOD

Frequency Domain

BF 2, User 1

OFDMA Formulator


Phase Shifter, User 1

Frequency Domain

BF 1, User 1

Vec tor Adder

Channel Coded Bits of User L

MOD

Frequency Domain

BF 2, User L

OFDMA Formulator


Phase Shifter, User L

Frequency Domain

BF 1, User L

Vec tor Adder

March 2006


Slide 73

doc.: IEEE 802.22-06/0005r5

Submission

Beamforming with Channel Delay Management

By adjusting timings D1 and D2, the overall delay of the channel can be changed.

Reflector 1Or repeater

Reflector 2Or repeater

CPE

Rich local scatters

Beam 1

Beam 2

Delay 1 T1 = τ1+ D1

Delay 2 T2 = τ2+ D2

Overall Delay|T1-T2| +δ

Pre-alignment& beamforming

Stream 1

Stream 2

When the overall channel delay exceeds the cyclic prefix period, spatial resolution of multipaths in the angular domain allows to alleviate the inter-block interference.

March 2006


Slide 74

doc.: IEEE 802.22-06/0005r5

Submission

Uplink SDMA(formerly Virtual MIMO)

• Uplink

• Multiple Antennas at BS and single antenna at each CPE

• Multiple CPEs share the same physical channel

• Spectrum efficiency increase linearly with CPE number if the CPE number is less than the number of BS antennas

CPE 1

CPE 2

Base

March 2006


Slide 75

doc.: IEEE 802.22-06/0005r5

Submission

IEEE 802.16e Uplink Channel Sounding

• Presented in January 2006: 22-06-0013-00-0000_Uplink_Channel_Sounding.ppt• ULCS is a means of providing channel response information to the BS on an as-needed basis

– CPE transmits sounding waveform on the UL to enable the BS to measure the channel response– Intended for TDD systems where UL&DL RF reciprocity can be leveraged

• ULCS enables Closed-Loop Transmit Antenna Array Techniques on the DL in TDD:– Baseband digital transmit beamforming– Transmit Spatial Division Multiple Access (SDMA)– Closed-loop Multiple Input Multiple Output (MIMO)

• ULCS provides an easier and better-performing alternative to other 802.16e Closed-Loop techniques with minimal added complexity to the CPE

– Lower channel measurement delay– Better frequency-response tracking

• Future-Proof: Transmit array algorithms can be upgraded at the BS with no impact on CPE– Technique is independent of the number of BS antennas

• Handles asymmetric bandwidth occupancy of UL&DL transmissions

March 2006


Slide 76

doc.: IEEE 802.22-06/0005r5

Submission

Multiple antennas on-going work

• A spatial channel model for the WRAN is currently under development by the joint proposers.

• Supporting features, such as uplink channel sounding, specific preamble design, MAC messages.

• Performance evaluation and selection of the proposed schemes.

March 2006


Slide 77

doc.: IEEE 802.22-06/0005r5

Submission

Spectrum Sensing

March 2006


Slide 78

doc.: IEEE 802.22-06/0005r5

Submission

Spectrum Sensing : Fact

• Spectrum sensing should be accurate enough to protect incumbent users

• Spectrum sensing should be fast enough to support the sensing protocol in MAC

• Spectrum sensing block should be able to be implemented by reasonable cost/resources

• “Spectrum sensing technology” is implementation technology.

• There is no single sensing technology can meet all the sensing requirement.

March 2006


Slide 79

doc.: IEEE 802.22-06/0005r5

Submission

Spectrum Sensing : What we proposed

• We proposed a “sensing system architecture”, not an individual sensing technology, which we believe is the most efficient way to support MAC while sustain accuracy.

• Within this system architecture, multiple sensing technologies can be chosen to meet the sensing requirements (time, sensitivity) by the manufacturer

• We’ve been trying to include various sensing technologies for primary user group to feel comfortable on WRAN

March 2006


Slide 80

doc.: IEEE 802.22-06/0005r5

Submission

Sensing Receiver Architecture

MAC

Fine/Feature

RFE

Energy Detection

Omni Antenna

Control

March 2006


Slide 81

doc.: IEEE 802.22-06/0005r5

Submission

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

March 2006


Slide 82

doc.: IEEE 802.22-06/0005r5

Submission

List of sensing techniques included in the proposal

• Energy detection– Analog integrator

– MRSS (Samsung/GT)

– RSSI (Philips)

– FFT

• Fine/Feature Detection– Cyclo-Stationary Feature Detection (Samsung)

– Field-sync detection (Philips)

– ATSC Segment Sync (Thomson)

– FFT based (Philips and Huawei)

– Optimum radiometer (France Telecom)

– Multi-cycle detector (France Telecom)

– Analog Auto-Correlation (Samsung/GT)

– Spectral correlation (Huawei)

March 2006


Slide 83

doc.: IEEE 802.22-06/0005r5

Submission

Spectrum Sensing : What we will do

• Each of the sensing technology will be rigorously evaluated by the procedure to be defined.

• Individual sensing technologies that pass the evaluation process shall be included the draft as an optional.

• Our proposal is open to new innovative sensing technology.

March 2006


Slide 84

doc.: IEEE 802.22-06/0005r5

Submission

Backup Slides

March 2006


Slide 85

doc.: IEEE 802.22-06/0005r5

Submission

Equal Gain Beamformer For Multiple Streams

• Let received vector be: – NT: No. of transmit antennae.– NR : No. of receive antennae (assumed here to be = no of streams)– H is the channel matrix (NR X NT),– Q is the beamforming matrix (NT X NR).– x is the data vector (NR X 1),

• Transmitted vector: • Equal-gain constraint implies that each row of Q has the same

power.• Let H = USVH be the SVD of H. • Then, if NT = NR, and Q = V, we get equal gain beamforming

because V is an orthonormal matrix.• If NT > NR, and Q = V(:, 1:NR), then each row of Q does not have

the same power => unequal gains.

nxHQr

xQy

March 2006


Slide 86

doc.: IEEE 802.22-06/0005r5

Submission

Quantized Equal-Gain Beamformer Simulation Scenario

• 2K FFT, 64 tones per user, all tones used for data transmission. ¼ cyclic prefix.

• Subchannelization: 16 groups of 4 tones, equally spaced over 6 MHz bandwidth. Each packet simulated had a randomly generated subcarrier set.

• Channel: 2sec RMS delay spread (total impulse response spread = 20sec), exponential Rayleigh fading, uncorrelated channels from each antenna.

• 1000 byte packets, each packet goes through a different channel realization, simulation run until 100 packet errors are accumulated.

March 2006


Slide 87

doc.: IEEE 802.22-06/0005r5

Submission

Quantized Equal-Gain Beamformer Performance

March 2006


Slide 88

doc.: IEEE 802.22-06/0005r5

Submission

CL SDMA Flowchart

CSI = channel state informationCQI = channel quality indicator

Base station CPE

TDD: uplink sounding pilots and CQI feedback

Downlink sounding pilots and data

Downlink pilots

Channel estimation and computation of CQI

Computation of transmit filters

Computation of receive filters and data detection

FDD: Quantized CSI and CQI feedback

(FDD: additional quantized CSI)

March 2006


Slide 89

doc.: IEEE 802.22-06/0005r5

Submission

Performance of downlink closed-loop SDMA with correlated fading at the transmitter

3GPP LTE suburban-macro small-scale fading channel model (mean CINR = 7.5 dB)

March 2006


Slide 90

doc.: IEEE 802.22-06/0005r5

Submission

Adaptive Beam-Forming (2)

• Adaptive array vs. Fixed-beam array– More Efficient CCI Suppression: Adaptive array system steers the

main beam to the direction of a desired signal, while steering nulls to the directions of undesired signals.

Figure. Adaptive array vs. fixed-beam array

1st co- channel interferer

desired signal

2nd co- channel interferer

fixed-beam adaptive array

March 2006


Slide 91

doc.: IEEE 802.22-06/0005r5

Submission

ABF Performance Evaluation

• Antenna Array– Array type: Linear equi-spaced array with half wavelength spacing

consisting of 8 antenna elements.

– Root-MUSIC is used to estimate the DOAs of incident signals.

– All incident signals are assumed to have zero elevation angle.

• Angular Spread– Laplacian model– All clusters are assumed to have the angular spread of 0.3o.

• Others– No. of OFDM symbols for reverse link preamble is 1.

– No. of sub-carriers assigned to users is 256.

– No. of sub-carriers per sub-band is 16 for reference signal method.

– No channel coding employed

March 2006


Slide 92

doc.: IEEE 802.22-06/0005r5

Submission

0.83 secrms delay

0.68 secrms delay

18.0o-11.2o9.5o-6.9o2.6o0oIncident angles*


0.37 Hz0.17 Hz2.5 Hz0.13 Hz00.1 HzDoppler frequency

-20 dB-16 dB-22 dB-7 dB0-6 dBRelative amplitude

11 sec7 sec4 sec2 sec0-3 secExcess delay

Path 6Path 5Path 4Path 3Path 2Path 1PROFILE B

0.37 Hz0.17 Hz0.13 Hz2.5 Hz0.10 Hz0Doppler frequency

-19 dB-24 dB-22 dB-15 dB-7 dB0Relative amplitude

21 sec13 sec11 sec8 sec3 sec0Excess delay

Path 6Path 5Path 4Path 3Path 2Path 1PROFILE A

0.83 secrms delay

0.68 secrms delay






Path 6Path 5Path 4Path 3Path 2Path 1PROFILE B

0.37 Hz0.17 Hz0.13 Hz2.5 Hz0.10 Hz0Doppler frequency

-19 dB-24 dB-22 dB-15 dB-7 dB0Relative amplitude

21 sec13 sec11 sec8 sec3 sec0Excess delay

Path 6Path 5Path 4Path 3Path 2Path 1PROFILE A

(* : defined for adaptive beam-forming)

Channel Parameters for ABF Simulation (1)

March 2006


Slide 93

doc.: IEEE 802.22-06/0005r5

Submission

Channel Parameters for ABF Simulation (2)

5.36 secrms delay

1.07 secrms delay

15.0o-11.2o7.7o-3.0o-0.86o0oIncident angles*





Path 6Path 5Path 4Path 3Path 2Path 1PROFILE D




Path 6Path 5Path 4Path 3Path 2Path 1PROFILE C

5.36 secrms delay

1.07 secrms delay






Path 6Path 5Path 4Path 3Path 2Path 1PROFILE D




Path 6Path 5Path 4Path 3Path 2Path 1PROFILE C

(* : defined for adaptive beam-forming)

March 2006


Slide 94

doc.: IEEE 802.22-06/0005r5

Submission

Figure. Comparison of BER performance for reverse link (INR = 25dB, interference DOAs =(20o, 30o), relative amplitude = (0dB, -3dB) )

Performance Evaluation : ABF Algorithms (1)

0 5 10 15 20 2510-4

10-3

10-2

10-1

100

Un

cod

ed

BE

R

SNR (dB)

Single AntennaDOA Based Reference Profile A Profile B Profile C Profile D

March 2006


Slide 95

doc.: IEEE 802.22-06/0005r5

Submission

Figure. Average output SINR vs. azimuth difference for reverse link ( Profile A, SNR = 15dB, INR = 25dB, relative amplitude = (0dB, -3dB) )


10 15 20 25 30 35 40 45 5012

14

16

18

20

22

24

A

vera

ge

Ou

tpu

t SIN

R (

dB

)

Azimuth Difference (Deg)

DOA Based Algorithm Reference Signal Method

Perfect interference cancellation : Output SINR = 24dB

March 2006


Slide 96

doc.: IEEE 802.22-06/0005r5

Submission

Figure. Channel mismatch effect for reverse link ( Profile A, INR = 25dB, interference DOAs = (20o, 30o), relative amplitude = (0dB, -3dB) )


0 5 10 15 20 2510-4

10-3

10-2

10-1

100

U

nco

de

d B

ER

SNR (dB)

No Errors

Amp Error = 10%, Phase Error = 10o



Dashed line : DOA Based Algorithm Solid line : Reference Signal Method

• Error distribution: truncated Gaussian

• Ref. signal method: insensitive due to self-healing nature

• DOA based method: relatively insensitive

March 2006


Slide 97

doc.: IEEE 802.22-06/0005r5

Submission

Figure. Effect of channel mismatch for forward link ( Profile A, INR = 25dB, interference DOAs = (20o, 30o), relative amplitude = (0dB, -3dB) )


0 5 10 15 20 2510-4

10-3

10-2

10-1

100

U

nco

ded

BE

R

SNR (dB)

No Errors

Amp Error = 0.1%, Phase Error = 0.1o




Dashed line : DOA Based Algorithm Solid line : Reference Signal Method

• Error distribution: truncated Gaussian

• Ref. signal method: extremely sensitive

• DOA based method: relatively insensitive

March 2006


Slide 98

doc.: IEEE 802.22-06/0005r5

Submission

Figure. BER performance of Alamouti’s scheme in 802.22 environments (QPSK, degree of correlation = 0.7)

Performance gain: 3.7dB ~ 7.5dB at 10-2 ~ 10-3 BER

Performance Evaluation : STBC (1)

0 5 10 15 20 2510-5

10-4

10-3

10-2

10-1

100

Modulation = QPSK No. of Rx Ant = 1 = 0.7

U

nco

de

d B

ER

Eb/No

Alamouti case Profile A Profile B Profile C Profile DNo diversity case Profile A Profile B Profile C Profile D

March 2006


Slide 99

doc.: IEEE 802.22-06/0005r5

Submission

Figure. BER performance of Alamouti’s scheme in 802.22 environments (16QAM, degree of correlation = 0.7)


0 5 10 15 20 2510-5

10-4

10-3

10-2

10-1

100

Modulation = 16QAM No. of Rx Ant = 1 = 0.7

U

nco

de

d B

ER

Eb/No



March 2006


Slide 100

doc.: IEEE 802.22-06/0005r5

Submission

Figure. BER performance of Alamouti’s scheme in 802.22 environments (64QAM, degree of correlation = 0.7)



0 5 10 15 20 2510-5

10-4

10-3

10-2

10-1

100

Modulation = 64QAM No. of Rx Ant = 1 = 0.7

U

ncod

ed B

ER

Eb/No


March 2006


Slide 101

doc.: IEEE 802.22-06/0005r5

Submission

Figure. BER performance vs. degree of correlation in 802.22 environments (Profile A, QPSK)


0 5 10 15 20 2510-5

10-4

10-3

10-2

10-1

100

Modulation = QPSK No. of Rx Ant = 1

Un

code

d B

ER

Eb/No

No diversity caseAlamoti case(Profile A) Correlation = 0.0 Correlation = 0.4 Correlation = 0.7 Correlation = 0.9

March 2006


Slide 102

doc.: IEEE 802.22-06/0005r5

Submission

Degree of Correlation vs. Antenna Separation

Figure. Degree of correlation vs. antenna separation for various angular spreads (Laplacian model, zero nominal azimuth angle)

0 2 4 6 8 10 12 14 16 18 200.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

4o

2o

1o

0.5o

De

gre

e o

f Co

rre

latio

n

Antenna Separation (wavelength)

0.3o

March 2006


Slide 103

doc.: IEEE 802.22-06/0005r5

Submission

FDFR

• The combination of pre-coder and the delay elements makes the error matrices full rank. FD.

• The loss by the tail edges becomes negligible as the block size increases.

• The interference from the previous vectors are subtracted while that from the later vectors are suppressed. The symbols within a vector are jointly decoded via ML, sphere decoder or any types of linear decoder.

March 2006


Slide 104

doc.: IEEE 802.22-06/0005r5

Submission


• PHY Proposal


• Conclusions

March 2006


Slide 105

doc.: IEEE 802.22-06/0005r5

Submission

Disclaimer

• The following set of slides are restricted to describe only the updates to the MAC proposal described in documents 22-06-0003-01-0000 and 22-06-0005-01-0000 (presented in January/2006)

• The following updates together with document 22-06-0003-03-0000 represent the entire joint ETRI-France Telecom-I2R-Motorola-Philips-Samsung-Thomson MAC proposal

March 2006


Slide 106

doc.: IEEE 802.22-06/0005r5

Submission

MAC Presentation Outline

• MAC Protocol– MAC layer data communication

• Support for Adaptive Antenna System (AAS)• Explicit outband signalling for hidden incumbent detection• Channel switch procedure

– Coexistence• Opportunistic in-band sensing• Credit tokens based rental protocol for inter-BS dynamic resource sharing• Enhanced measurement and channel management capabilities

– Clarifications• Frequency hopping• Support for Single Channel CPEs• Quiet period management for sensing

• Performance Evaluation– Synchronization of overlapping BSs– CBP

March 2006


Slide 107

doc.: IEEE 802.22-06/0005r5

Submission







March 2006


Slide 108

doc.: IEEE 802.22-06/0005r5

Submission

MAC Highlights

• Some aspects of MAC have been inspired by the 802.16 MAC– E.g., Frame format and QoS model

• However, major enhancements have been made– A new superframe structure for better coexistence and self-coexistence,

synchronization, Part 74 beacon support, support for bonding, etc.– Support for multiple channel operation (contiguous or not)– Enhanced support for Adaptive Antenna System– Coexistence with both incumbents and itself (self-coexistence);

• Incumbent user avoidance and Spectrum measurements (incumbents and itself)• Channel classification and Management• Dynamic resource sharing, Coexistence Beacon Protocol (CBP), and Etiquette• Synchronization of overlapping BSs and quiet periods• Two-stage fast and fine sensing mechanism and opportunistic sensing• Embedded wireless microphone beacon mechanism• Clustering support

March 2006


Slide 109

doc.: IEEE 802.22-06/0005r5

Submission

Support for Adaptive Antenna System (AAS)

• Optional mode

• MAC takes advantage of the increased capacity and range offered by AAS– Similar to 802.16e

• Frame structure simultaneously support AAS and non-AAS traffic

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

...

MAC Slot Number

Regula

rP

ream

ble

FCH

DS

-MA

PU

S-M

AP

Self-

coexi

stence

Ranging

UCS Notification

Burst CPE #3

Burst CPE #2

Burst CPE #1

AASDS Zone

Burst CPE #1

Burst CPE #2

Burst CPE #4

Burst CPE #5

Burst CPE #3

Burst CPE #4

Self-

coexi

stence

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

Logic

al M

AC

Channel N

um

ber

s

s+1

s+2

s+L

BW Request

RTG

AA

SP

ream

ble

AASUS Zone

March 2006


Slide 110

doc.: IEEE 802.22-06/0005r5

Submission


• For AAS downlink synchronization, a CPE utilizes the broadcast preamble

• For network entry and initialization, two options are possible:– CPE receives enough energy from the broadcast channel that

allows it to decode control information (e.g., UCD/DCD and maps)• Hence, proceeds with network entry and initialization

– Otherwise, BS shall dedicate a fixed and pre-defined portion of the superframe structure as initial ranging contention slots• Sufficient slots are used by the CPE as to allow the BS enough time to

beamform towards the CPE• CPE shall wait for transmission from BS before retry• Network entry and initialization proceeds after that

March 2006


Slide 111

doc.: IEEE 802.22-06/0005r5

Submission



...


Channelt-1

Channelt

Channel t+1

Time

Preamble SCH

Preamble SCH

Fre

qu

ency

Preamble SCHFrame

0Frame

1Frame

m... ...

AW

AW

AW

AW Preamble SCH

Preamble SCH

Preamble SCHFrame

0Frame

1Frame

m...

AW

AW

AW

Alert-Window (AW)

• Contention slots for initial ranging• Used by AAS CPEs and by single channel CPEs

March 2006


Slide 112

doc.: IEEE 802.22-06/0005r5

Submission


• Channel state information can be done in two ways:– Reciprocity: Assumes the upstream channel state estimation as the

downstream channel state– Feedback: CPE explicitly transmits the estimated channel to the

BS

• Two channel feedback options are available:– New MAC control messages (namely, AAS-CFB-REQ and AAS-

CFB-RSP) have been defined– Piggybacked together with the existing measurement reports used

for incumbents and other 802.22 systems

• Bandwidth request, incumbent notifications, measurement reports, etc.:– Can be done using either the broadcast allocations or by polling

March 2006


Slide 113

doc.: IEEE 802.22-06/0005r5

Submission

Hidden Incumbent Systems

• A WRAN System is on service in channel x.– CR BS sensed some channels and it recognized channel x was available, or BS just

started the service based on its database information.

• Some CPEs inside the incumbent system radio area may not be able to decode the CR BS signal because of strong interference.

– So, the CPEs cannot report the existence of the incumbent system and current status to the BS.

– BS cannot recognize this situation because of no information.

– Also, some incumbent users have experienced interference from the WRAN system.

Ch x

CPE

Ch x

Incumbent System

CR SystemNot overlapped CR CPE

Overlapped CR CPE(cannot decode CR Signaland cannot report anything)

Incumbent user

March 2006


Slide 114

doc.: IEEE 802.22-06/0005r5

Submission

• Hidden incumbent case occurs– When a BS starts the service,– The BS changes the service channel

• Candidate channel broadcasting by BS and sensing reports for the candidate bands by CPEs can reduce the possibility of hidden incumbent system.

• But, BS may change its service channel without notification.

• Problem– CPEs inside the overlapped area are aware of the strong interference by incumbent

system.– How to report it to BS?

• Implicit hidden incumbent case detection– A BS periodically sends sensing request and all CPEs respond.– If a BS did not receive sensing responses from some CPEs, then sends again.– After some trials, if still some CPEs don’t respond, BS notices hidden incumbent

system appearance and changes the channel.– Still there remains some problems some CPEs power off ( Confuses BS as if hidden incumbent case occurs) CPEs inside the overlapped area just turn on, hence the BS doesn’t know the

existence of CPEs.

March 2006


Slide 115

doc.: IEEE 802.22-06/0005r5

Submission

Explicit OutBand Signaling for Hidden Incumbent Case Detection

• Hidden Incumbent System Case Method– BS periodically broadcasts the information on current channel in

some of other unoccupied channels (e.g. candidate channels).• Out-band signal: control signal on the band other than current band.• This broadcasting signal follows the same PHY and MAC frame

architecture (not to necessitate additional protocol or PHY module).

– CPEs that are not able to decode the BS’s current service channel try to sense other channels to locate the BS signal.

– If CPEs receive the explicit out-band broadcast signal,• It recognizes the current service channel id.• If the current channel is already sensed and is found to be not

decodable, then the CPE sends a report to the BS using the upstream in out-band.

– After noticing the existence of the hidden incumbent,• BS changes its service channel to other available band.

March 2006


Slide 116

doc.: IEEE 802.22-06/0005r5

Submission

Ch A

Time

channelCh C

Ch B

Explicit outband signaling period

CPE that cannot decode the current service channel will try to sense other channels

The CPE finally receives at least one of the periodic outband broadcast signals

Frequency

Ch A Ch B Ch C Ch D Ch E Ch F Ch X Ch Y

Not available

Not available

CurrentServiceChannel

BS

OutbandSignal

broadcast

OutbandSignal

broadcast

OutbandSignal

broadcast

OutbandSignal

broadcast OutbandSignal

broadcast

Frequency

Ch A Ch B Ch C Ch D Ch E Ch F Ch X

Not available

Not available

CPENot

available

Ch Y

OutbandSignal

broadcastReport

service signal

OutbandSignal

broadcast

It can be decided by incumbent system detection time requirement.

March 2006


Slide 117

doc.: IEEE 802.22-06/0005r5

Submission

• Explicit out-band broadcast signal

– Follow the usual PHY and MAC frame architecture like in the service channel

– In SCH: need a flag to differentiate

• Regular service MAC frame (in service channel)

• Out-band broadcast signal MAC frame (for broadcasting channel)

– In DS-Bust: include service channel information

• Service channel numbers, candidate channel numbers, …

• Hidden incumbent case report

– When a CPE receives a out-band signal and if the current service channel is not decodable by the CPE, then

– Sends “Hidden incumbent report” to BS using the broadcasting US-Burst

FCH

US-MAP

DS - Burst DS-

MAP

US- Burst

SCH

March 2006


Slide 118

doc.: IEEE 802.22-06/0005r5

Submission

• Hidden Incumbent System Report– CPE report can be either of

• “the current service channel x is not decodable”• “the current service channel x is used by a incumbent system”

– If the CPE can recognize incumbent signal.– CPE report can also include sensing result for some other channels.

• US resource (data-burst) allocation for “hidden incumbent report” report.– BS may allocate explicit resource to each CPE after CPE initialization procedure –

overhead– BS may list up slotted US busts for unknown CPEs, which possibly reply their

reports using one of the slotted busts. Slotted US burst size can be determined in accordance with the maximum hidden incumbent report size .

• CPEs that need to send “hidden incumbent report” contend each other• Random back-off to send a message.

• Some overheads necessary in BS to broadcast out-band signals in different channels.

• CPEs do not need any change on their implementation.• Implicit method can supplement the explicit method.

March 2006


Slide 119

doc.: IEEE 802.22-06/0005r5

Submission

Channel Switch Procedure

• WRAN system build a candidate channel list using distributed sensing.• When incumbent users and other WRAN system are detected in the current

operating channel, – The BS selects a channel CHselect from the candidate channel list, either randomly or based on

some algorithms.– Randomly selects a wait time twait from a time window [ Tmin, Tmax ]– Start a wait timer with Twait as the expiration time– Advertises the channel selection using backhaul channel or WRAN air interface before

jumping to CHselect.

• Meanwhile the WRAN system sense CHselect for incumbent signals and other WRAN systems

– If the channel CHselect is still idle/available, it jumps to CHselect when the wait timer expires. – If incumbent signals or other WRAN systems exist in CHselect , it goes back to the beginning

to select another channel from the candidate channel list or its previously operated channel if occupied by incumbent users

• If collision occurs after channel switch, it increase tmax and goes back to the beginning to select another channel from the candidate channel list or its previously operated channel if not occupied by incumbent users

– Otherwise, it decrease Tmax and remove CHselect from the candidate channel list.

March 2006


Slide 120

doc.: IEEE 802.22-06/0005r5

Submission

Selects a channel CHselect from the candidate channel list

Start a wait timer with Twait as the expire time

Randomly selects a wait time Twait from a time window [ Tmin, Tmax ]

Advertise the channel selection CHselect

Sense channel CHselect

Channel CHselect idle?

Wait timer expire?

Switch to channel CHselect

Stop the wait timerAdd previously operating channel not occupied by

incumbents to the candidate channel list

Detect incumbent users and other WRAN system on the current operating channel

Stop

Increase Tmax

no

yes

Incumbent users and other WRAN system on Channel CHselect?

yes

yes

no

Remove CHselect from the candidate channel list and reduce Tmax

no

Remove CHselect from the candidate

channel list

March 2006


Slide 121

doc.: IEEE 802.22-06/0005r5

Submission







March 2006


Slide 122

doc.: IEEE 802.22-06/0005r5

Submission

The Opportunistic In-band Sensing Scheme

• Applicable for those cases where the traffic is low, and so sensing can take place within a frame– For these cases, the opportunistic in-band sensing can have

performance benefits such as reducing detection time and improving detection accuracy

• This scheme may be able to run in parallel with the out-of-band sensing algorithm:– However, whenever there is contention between the opportunistic

in-band sensing and out-of-band sensing, out-of-band sensing shall take precedence

March 2006


Slide 123

doc.: IEEE 802.22-06/0005r5

Submission

The Opportunistic In-band Sensing Scheme (cont.)

• The main idea is to use common “sensing-eligible” frames to do in-band sensing

• A “sensing-eligible” frame is:– A frame with no traffic, i.e. no US or DS traffic

– A frame at which the backlogged traffic (both US and DS) is less than the remaining capacity in the current superframe and no sensing frame has been allocated in the superframe

– The last frame of the superframe and no sensing frame has been allocated in the superframe

• A “sensing-eligible” frame is designated as a sensing frame if it is not marked for use for out-of-band sensing

March 2006


Slide 124

doc.: IEEE 802.22-06/0005r5

Submission

Start of a newframe

Current framehas traffic?

backloggedtraffic

< remainingcapacity?

Is this the lastframe?

Sensing frameallocated in

superframe?

Current frame isa sensing frame

no

yes

yes

no

yes

no

Current frame nota sensing frame

no

yes

The opportunistic in-band sensing scheme

The Opportunistic In-band Sensing Scheme (cont.)

March 2006


Slide 125

doc.: IEEE 802.22-06/0005r5

Submission

Credit Tokens based Rental Protocol for Inter-BS Dynamic Resource Sharing

• Rental Protocol– Offeror

– Renter

• Problem: – How to deal access/usage contention issues when several renters compete

to access to the same offer at the same time ?

– How to schedule the competing renters in a fair fashion while maximizing the spectrum efficiency ?

• The proposed mechanism complements the existing proposal– It introduces a cooperative sharing negotiation protocol: credit tokens

based rental protocol between one offeror and several renters

March 2006


Slide 126

doc.: IEEE 802.22-06/0005r5

Submission


(cont.)• Definition

– Radio channel: time*frequency.– BIN = time unit*frequency unit.– A radio channel = a number of BINs.– Credit Tokens (CT): « money like » unit.

• What can be shared/negotiated?– Number of BINs for a given time duration.– The starting time of the sharing.– The ending time of the sharing.

• Principles– Each offeror and renter BS is prior allocated with a given credit tokens budget.– A BIN is charged as a number of CT per time*frequency unit.– A radio channel can be shared by exchanging CT between offeror and renter.– The exchange is dynamic and supported through the CT transactions.

March 2006


Slide 127

doc.: IEEE 802.22-06/0005r5

Submission


(cont.)• Principles

– Transactions rely on the real time and dynamic usage of reserve price auctionning and bidding mechanisms (e.g. ascending bid auction) to solve contention issues between renters BSs:• Offeror = auctionner• Renter = bidder

– BSs do not manipulate money. CT is used for self coordination in a distributed fashion between BS (self gouvernance).

– Incentive for sharing and fairness support is achieved through CT awarding.

• The credit tokens usage at each BS is ruled by the radio etiquette.

March 2006


Slide 128

doc.: IEEE 802.22-06/0005r5

Submission

Credit Tokens based Scheduling Cycle

Resou

rce U

sage p

hase

(10) BW Granting

(9) Transaction

(8) Final Bidding results/Pricing

(5) (n-1)th Bidding results

(6) Express new bidding (nth)

(7) nth Bidding results

Offeror BS Renter BS

nth iteration

(n >

1) of th

e dyn

amic cred

it tok

ens b

ased

auction

ing/b

idd

ing

ph

ase

Fin

al pricin

g an

d

Tran

saction

ph

ase

Cred

it token

s b

ased B

W

Gran

ting

ph

ase

First iteration

(n =

1) of th

e dyn

amic

credit tok

ens

based

auction

ing/b

idd

ing

ph

ase

Interest

expressin

g p

hase

(1) Awareness/Advertising

(3) Inform bidding phasing

(2) Express interest

(5) 1st Bidding results

(4) Express initial bidding

Offeror BS Renter BS

Ad

vertising p

hase

March 2006


Slide 129

doc.: IEEE 802.22-06/0005r5

Submission


(cont.)• This credit tokens based rental protocol can be implemented:

– either over the air (MAC level)– or the backhaul (wired)

• For the over air implementation, the credit tokens based rental protocol rules the MAC frame structure sharing between renters and offerors

• Scalable for different resoure renting timescales– Different auctioning strategies can be applied depending on the time constraints for

the negotiation

• Credit token charging mechanisms (different auctioning strategies) can be dynamically tuned to the context through the radio etiquette

– Space time traffic intensity variations in each cell– Number of bidders– ...

March 2006


Slide 130

doc.: IEEE 802.22-06/0005r5

Submission

Enhanced Measurement Capability

• Besides the detailed and on-channel report, a CPE can now send a Consolidated Spectrum Occupancy Report– A Consolidated Spectrum Occupancy Report conveys a summary

of the overall spectrum occupancy from the point of view of a CPE

• For a particular channel, the CPE reports its state as a 3 bit field:– Unmeasured

– Vacant

– Occupied (i.e., energy detected)

– Occupied by an Incumbent

– Occupied by 802.22

March 2006


Slide 131

doc.: IEEE 802.22-06/0005r5

Submission

Enhanced Channel Management Capability

• Based on the measurement reports from CPEs, a BS can transmit a Channel Occupancy Update message to CPEs– Allows quicker recovery, more efficient measurements, etc.

• Similar to a CPE, for a particular channel the BS reports its state as a 3 bit field:– Unmeasured– Vacant– Occupied (i.e., energy detected)– Occupied by an Incumbent– Occupied by 802.22

March 2006


Slide 132

doc.: IEEE 802.22-06/0005r5

Submission







March 2006


Slide 133

doc.: IEEE 802.22-06/0005r5

Submission

Frequency Hopping

• Purpose– To dismiss any presumption that the proposed MAC does not allow

frequency hopping

• Treated as an optional implementation issue provided the technical hurdles can be overcome

• In order to avoid an in-band quiet period, a WRAN may hop to a Channel A provided:– The Channel A evaluation meets the Channel Availability Check Time as

specified in the FRD

– The Channel A is not occupied by any incumbent

– The Channel A is not occupied by any 802.22 network• Otherwise, it may be worse than sticking to your current channel

– Adjacent channels have also been checked for the presence of incumbents, as to adhere to the EIRP profile

March 2006


Slide 134

doc.: IEEE 802.22-06/0005r5

Submission

Support for Single Channel CPE

• At this point, channel bonding (of up to 3 contiguous TV channels) is an optional feature– This implies that BSs and CPEs may have different capabilities

• What happens if a BS is in channel bonding mode when a single channel CPE attempts to joint the network?

• To support this feature, an Alert Window (AW) is added to the superframe structure– Used to notify the BS about incoming CPEs who cannot operate in

the same mode as the BS

March 2006


Slide 135

doc.: IEEE 802.22-06/0005r5

Submission

Support for Single Channel CPE (cont.)


...


Unit Channelt-1

Unit Channelt

Unit Channelt+1

Time

Preamble SCH

Preamble SCH

Fre

qu

en

cy

Preamble SCHFrame

0Frame

1Frame

m... ...Frame

1Frame

0

AW

Frame2

Frame0

Frame2

Frame0

Frame2

Preamble SCH

Preamble SCH

Preamble SCH

AW

AW

AW

Alert-Window (AW)

• Contention slots for initial ranging• Used by AAS CPEs and by single channel CPEs

March 2006


Slide 136

doc.: IEEE 802.22-06/0005r5

Submission

Quiet Period Management for Sensing

• Background– A potentially very large number of channels (up to N±15) have to

be periodically sensed for the presence of incumbents– At the same time, support to QoS traffic requires delays as low as

20ms (see FRD)

• Question– How is sensing done as to meet these requirements?

• Answer– Sensing is a two-stage process

• Stage 1: Fast sensing (e.g., energy detection)• Stage 2: Only if needed, perform fine sensing (feature detection)

March 2006


Slide 137

doc.: IEEE 802.22-06/0005r5

Submission

Quiet Period Management for Sensing (cont.)

• Quiet period structure

• The fast sensing is performed in-band only– May or may not be scheduled by the BS (e.g., between two

consecutive MAC frames)– Upon BS request, a consolidated report on the fast sensing

outcome is sent by CPEs– BS then determines the need for the next fine sensing and how

much time is required

BS1

Fast sensing 802.22 Transmission

Channel Detection TimeFast sensing Fine sensing

Fine sensing

Time


March 2006


Slide 138

doc.: IEEE 802.22-06/0005r5

Submission


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

...

MAC Slot Number

Pre

am

ble

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

exi

ste

nce

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

TV Channel N

TV Channel N+1

DS US

Lo

gic

al M

AC

Ch

an

ne

l Nu

mb

er

s

s+1

s+2

s+L

BW Request

Sensing RTG

Fast Sensing

March 2006


Slide 139

doc.: IEEE 802.22-06/0005r5

Submission


• Since quiet periods from overlapping 802.22 cells are synchronized, sensing is highly effective

BS1

BS2

Time

BS3

Fast sensing 802.22 TransmissionFine sensing







March 2006


Slide 140

doc.: IEEE 802.22-06/0005r5

Submission


• Given that the nature of incumbent appearance on a channel is sparse (e.g., new TV stations do not come on the air every hour):– The fast sensing stage will be enough most of the time

– Hence, the fine sensing stage will not need to be performed

– Even if the fine sensing stage is required to be performed, its duration will exactly fit how much is required to be measured

• Therefore, with this mechanism: – Not only will incumbents have their protection guaranteed

– The stringent QoS requirements specified in the FRD will be met

March 2006


Slide 141

doc.: IEEE 802.22-06/0005r5

Submission







March 2006


Slide 142

doc.: IEEE 802.22-06/0005r5

Submission

Performance Evaluation

• Two aspects of the proposal are further evaluated– Distributed synchronization of overlapping 802.22 cells

• Four (4) step-by-step scenarios

• Overall convergence time for tens of thousands of scenarios

– Additional CBP protocol evaluation, which assesses• Self-coexistence

• Distributed quiet period synchronization of overlapping 802.22 cells

March 2006


Slide 143

doc.: IEEE 802.22-06/0005r5

Submission

Synchronization of Overlapping WRANs

• For all simulations– Number besides a node is the superframe transmission time (STT)

– Red line between nodes means nodes in range and STT NOT aligned

– Blue line between nodes means nodes in range and STT aligned

– Units• Time is milliseconds

• Space is kilometers

March 2006


Slide 144

doc.: IEEE 802.22-06/0005r5

Submission

Synchronization of Overlapping WRANs:Scenario 1

• A total of 24 WRANs are considered

• BSs and CPEs have a radio range of 25 Km

March 2006


Slide 145

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 146

doc.: IEEE 802.22-06/0005r5

Submission



• All WRANs power up at the same time (worst case analysis)


March 2006


Slide 147

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 148

doc.: IEEE 802.22-06/0005r5

Submission



• All WRANs power up at the same time (worst case analysis)– Random STT at startup


March 2006


Slide 149

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 150

doc.: IEEE 802.22-06/0005r5

Submission



• All WRANs power up at the same time (worst case analysis)– Random STT at startup


March 2006


Slide 151

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 152

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 153

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 154

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 155

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 156

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 157

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 158

doc.: IEEE 802.22-06/0005r5

Submission

March 2006


Slide 159

doc.: IEEE 802.22-06/0005r5

Submission

Synchronization of Overlapping WRANs:Overall Convergence Time

• Comprehensive evaluation of the synchronization mechanism– Used for self-

coexistence (e.g., CBP) as well as for quiet periods

• Results show the quick convergence and efficiency of the algorithm– A similar scheme is

used in the WiMedia UWB MAC

March 2006


Slide 160

doc.: IEEE 802.22-06/0005r5

Submission

CBP/Synchronization

• Evaluate the self-coexistence mechanisms of the proposed MAC– Synchronization– CBP in every frame

• The number of overlapping 802.22 cells are progressively increased– Up to 4 cells are simulated– BSs and CPEs start at random

• Network is fully loaded and traffic is uniform

1 cell:

2 cells:

March 2006


Slide 161

doc.: IEEE 802.22-06/0005r5

Submission

CBP/Synchronization (cont.)

3 cells:

4 cells:

March 2006


Slide 162

doc.: IEEE 802.22-06/0005r5

Submission

CBP/Synchronization (cont.)

• Simple scheduler

• CBP together with Synchronization can provide significant performance improvements– Since CBP is under control of

the BS, it can be made adaptive

March 2006


Slide 163

doc.: IEEE 802.22-06/0005r5

Submission


• PHY Proposal


• Conclusions

March 2006


Slide 164

doc.: IEEE 802.22-06/0005r5

Submission

Conclusions

• Presented the PHY proposal and updates to the MAC proposal– The proposal contains numerous mechanisms to protect incumbents while

meeting the requirements set forth by the 802.22 WG

• PHY– Based on OFDMA– Flexible channel configurations– TV and Part 74 service detection and protection

• MAC– Coexistence is a key feature

• Incumbent protection• Self-coexistence

– CBP, dynamic resource sharing, channel bonding, etc.

doc.: ieee 802.22-06/0005r5 submission march 2006 etri, ft, i2r, motorola, philips, samsung,...

Documents

statement ieee standards

wran systems ieee p802

patent policy

patent holder

patent applications

draft publication

060005r5 submission

joy laskargeorgia institute