doc.: ieee 802.22-05-0100-00-0000 submission november 2005 ashish pandharipande, saitslide 1...

November 2005

Ashish Pandharipande, SAIT

Slide 1

doc.: IEEE 802.22-05-0100-00-0000

Submission

Technology Proposal IEEE P802.22 Wireless RANs Date: 2005-11-07

Name Company Address Phone email Ashish Pandharipande Samsung Advanced

Institute of Technology SAIT, P.O. Box 111, Suwon 440-600, Korea

+82 010-6335-7784 [email protected]

Jae-Myung Kim Inha University Electrical Engineering Department, Inha University, Korea

[email protected]

David Mazzarese Samsung Electronics Co. Ltd.

Dong Suwon P.O. BOX 105, 416, Maetan-3dong, Yeongtong-gu, Suwon-si, Gyeonggi-do Korea 442-600

+82 10 3279 5210 [email protected]

Baowei Ji Samsung Telecommunications America

1301 E. Lookout Dr. Richardson, TX 75082

+1 972-761-7167 [email protected]

Authors:

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].>

http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf

mailto:[email protected]

mailto:[email protected]

November 2005


Slide 2

doc.: IEEE 802.22-05-0100-00-0000

Submission

Contributors

Section Organization Contributors Email

1. WRAN sensing Samsung Advanced Institute of Technology (SAIT)

Ashish Pandharipande, Duckdong Hwang

[email protected], [email protected]

2. Interference management Samsung Electronics Ltd. David Mazzarese [email protected]

3. WRAN MAC SAIT-Inha University Sang-Jo Yoo, Ashish Pandharipande

[email protected]

4. WRAN PHY Inha University Jaehak Chung, Jae-Myung Kim

[email protected], [email protected]

5. Misc MAC-PHY issues Samsung Telecom America Baowei Ji [email protected]

November 2005


Slide 3

doc.: IEEE 802.22-05-0100-00-0000

Submission

Abstract

This document provides technology solutions to meet functional requirements of an IEEE 802.22 based WRAN system. Keeping in view the unique requirements imposed on WRANs to operate while avoiding interference to licensed incumbents and coexistence among WRANs, we propose an OFDM(A) solution in conjunction with a set of MAC protocols, and provide distributed sensing and interference management solutions.

November 2005


Slide 4

doc.: IEEE 802.22-05-0100-00-0000

Submission

WRAN Proposal Overview• Sensing

– Local detection algorithms– Information fusion in distributed sensing– Interference avoidance to licensed incumbents– Coexistence among WRANs

• MAC– Frame structure definitions– Sensing management– Initialization procedures– Connection management and QoS support– Dynamic frequency change– Inter-WRAN communication, coexistence and resource sharing

• Physical Layer– OFDM(A) air interface– Support for single channel TDD/Multi-channel FDD and TDD– Adaptive modulation and coding modes for variable data rate support– Multiple antenna technology at BS

Sensing

PHY

MAC

November 2005


Slide 5

doc.: IEEE 802.22-05-0100-00-0000

Submission

Overview of WRAN Basic Architecture• Wireless Regional Area Network (WRAN)

– Point-Multipoint structure– Unlicensed operation over VHF-UHF spectrum range– Large service coverage (> 30 Kms)– Operation under interference avoidance to licensed services such as TV

broadcasting– Coexistence among unlicensed systems WRAN BS

Customer Premise Equipment (CPE)

CPE

CPE

CPE

CPE

CPE

November 2005


Slide 6

doc.: IEEE 802.22-05-0100-00-0000

Submission

1. WRAN sensing

• Solutions to address requirements in the following sections of the FRD– General requirements of Sections 5, 14 and 15

November 2005


Slide 7

doc.: IEEE 802.22-05-0100-00-0000

Submission

Sensing and associated modules at WRAN BS

TV usage database

Sensinginformation

module

SG forPart 74 devices

Dynamic map of Spectrum usage

Interference management

module

WRAN radio resource

allocation

WRANcoexistence

Licensed deviceprotection

Regional WRAN information base

Inter-WRAN resource sharing

module

Local WRAN information base

November 2005


Slide 8

doc.: IEEE 802.22-05-0100-00-0000

Submission

Overview of WRAN distributed sensing• WRAN BS has to determine

– Whether a signal is present or not in a given TV channel– Binary hypothesis testing (signal present or signal absent) problem– If yes, which ones

• WRAN BS relies on a central sensing decision unit (CSDU) to make global decision on channel occupancy– Distributed local detection by CPEs followed by detection information fusion

at CSDU to enhance reliability of sensing• Signal types to be considered

– Licensed incumbents• TV signals• Part 74 device signals

– Unlicensed systems• WRAN• Others?

• Different interference management solutions apply depending on which signals are detected

November 2005


Slide 9

doc.: IEEE 802.22-05-0100-00-0000

Submission

Distributed sensing overview

November 2005


Slide 10

doc.: IEEE 802.22-05-0100-00-0000

Submission

Local detection problem formulation• Local detection performed at each CPE• Signal detection

– Signal x(k), that is transmitted over channel h(k), to be detected in presence of AWGN n(k)

• h(k) is the impulse response of channel between Tx and CPE Rx

0

1

[signal absent hypothesis] : ( ) ( ) [signal present hypothesis] : ( ) ( )* ( ) ( )

H x k n kH x k h k s k n k

November 2005


Slide 11

doc.: IEEE 802.22-05-0100-00-0000

Submission

Cyclostationarity based signal detection• Signal x(k) is cyclostationary with period P if

• Cyclic autocorrelation and cyclic power spectrum density

• Various forms of detectors can be derived from cyclic power spectrum density

*( , ) [ ( ) ( )] ( , )x xR n k E x n x k R n P k P

( ) * 21( ) lim [ ( ) ].[ ( ) ] and ( ) ( )2 1

Nj n k j n j fk

x x xN n N k

R k x n k e x n e S f R k eN

Sliding N-pt FFT

x(n) Correlate and average sum

Feature detector

/ 2 1 / 2 12 ( ) / *

/ 2 / 2

1( , ) ( ) ( , ) ( , ) ( , )2 2

s

t

N Mj f n p f

T x T Tp N m M

mfs mfsX n f x n p e S n f X n f X n fMN N N

Signal attributes–Power–Modulation–Symbol frequency

November 2005


Slide 12

doc.: IEEE 802.22-05-0100-00-0000

Submission

Proposed local detection algorithm

• Detection based on cyclostationary properties exhibited by large class of signals (eg., PSK, QAM, VSB, OFDM, CDMA, …)

• Basic mode of detection algorithm– Energy detection– Used in high SNR regimes for pilot/carrier/signature detection type schemes

• Enhanced mode of detection algorithm– Feature detection– Used in low SNR regimes– Especially useful during initialization procedures where BS is looking for an

empty channel in low SNR conditions

November 2005


Slide 13

doc.: IEEE 802.22-05-0100-00-0000

Submission

Advantages of cyclostationary detection• Cyclic spectrum domain a richer domain for signal analysis than

conventional power spectrum• Robust to noise

– Stationary noise exhibits no cyclic correlations

• Better detector performance even in low SNR regions• Signal classification ability

– Different signals have different cycle frequencies and exhibit distinct spectral characteristics

• Can be used as an energy detector in alpha = 0 mode– Flexibility of operation

0

2 0 0

*

( ), 0, signal absent

| ( ) | ( ) ( ), 0, signal present( ) 0, 0, signal absent

( ) ( )2 2

n

s n

x

s

S f

H f S f S fS f

H f H f S

=

( ), 0, signal presentf

November 2005


Slide 14

doc.: IEEE 802.22-05-0100-00-0000

Submission

Feedback of sensing result and fusion rules • Option 1: Data fusion

– Each sensing element makes raw observations but does not make a decision as to whether a signal is present or not

– It processes the raw observations and sends the processed information to the CSDU. For eg., each CPE may feed back quantized values of energy when in energy detector mode

– At the CSDU, the sensing reports from the Q reporting CPEs is fused using the decision:

• Thresholds chosen so as to meet a pre-specified probability of false-alarm

• Option 2: Decision fusion– Each sensing element makes raw observations, processes these observations and makes a

detection decision as to whether a signal is present or not– It then sends the decision bit Di (1/0) to the CSDU

– At the CSDU, the individual decisions Di are fused into a final decision based on the following rule:

• Parameters chosen so as to meet a pre-specified probability of false-alarm

1 0

1

Declare signal present ( ) if ; else declare Q

i g

i

H E T H

1 0

1

Declare signal present ( ) if ; else declare Q

i g

i

H D T H

November 2005


Slide 15

doc.: IEEE 802.22-05-0100-00-0000

Submission

Detecting other WRANs

• Unique ID/spectral signature

• Regional WRAN information base– Attractive for its support for inter-WRAN communication

• Feature detection– Easy to detect OFDM signal with known symbol rate using cyclostationary

methods

November 2005


Slide 16

doc.: IEEE 802.22-05-0100-00-0000

Submission

Dynamic map of collated sensing reports from CPEs

CPE IDs CPE location

CPE sensing and classification and classification report *[Characteristics of signals detected]

Power of signal type

1

Spectrum occupancy of signal

type 1


2


type 2

…

Channel number

k

Data fusion case; *In case of WRANs, report also WRAN ID

CPE IDs CPE location

CPE sensing report [Characteristics of signals detected]


1


type 1


2


type 2

…

Channel number

k+1

.

.

.

.

.

.

November 2005


Slide 17

doc.: IEEE 802.22-05-0100-00-0000

Submission

Spectrum usage map

Information fusion ofdistributed sensing results

Sensing measurements TV usage database

Signal classification and footprint characteristics

Licensed incumbents Other WRANs Other licensed exempt

Channel N-1 ...

.

.

.

.

.

.

Channel N • type of incumbent• spatial footprint• spectral footprint

• BS ID• spatial footprint• spectral footprint

• BS ID• spatial footprint• spectral footprint

Channel N+1 ...

.

.

.

.

.

.

November 2005


Slide 18

doc.: IEEE 802.22-yy/xxxxr0

Submission

Local WRAN information base

WRAN BS ID

BS location

CPE IDs

CPE location

CPE DL CPE UL QoS and resource allocation information

SNR Service requirement

CPE MCS

CPE Tx power

…

• Information base contains current resource allocation of CPEs associated to the WRAN

November 2005


Slide 19

doc.: IEEE 802.22-yy/xxxxr0

Submission

Regional WRAN information base

Operator ID WRAN BS ID

WRAN BS location

Currently occupied spectrum

occupancy

Spectrum resources

available for sharing

Other parameters to facilitate inter-

WRAN resource sharing

…

• Information base contains WRAN information that can be accessed by other WRANs for facilitating coexistence and resource sharing

November 2005


Slide 20

doc.: IEEE 802.22-05-0100-00-0000

Submission

2. WRAN maximum transmit power constraint for interference management and coexistence

• Solutions to address requirements in the following sections of the FRD– Requirements of Sections 15.1.1.5, 15.1.6 and 15.2 (Coexistence and

interference-mitigation)• 15.1.1.5. Algorithms for Avoidance of Interference to Incumbents• 15.1.6. Maximum Power for WRAN CPEs to Avoid Interference to TV Operation• 15.2. WRAN Systems Coexistence/Sharing

November 2005


Slide 21

doc.: IEEE 802.22-05-0100-00-0000

Submission

Place of proposed interference management module in the system

Database

Sensing measurementsSet of minimum

constraints for QoS scheduler

optimization

Radio m

apFootprints of

incumbent and

coexisting WR

AN

s

QoS

scheduling & resource allocation (R

RM

):• in opportunistic spectrum

access channels• in dedicated channels (for coexistence)

Module that computes the

constraints relative to

coexistence

Module that computes the

constraints relative to the protection of incumbents

Interference management module

Constraints from WRANs negotiation outcome

November 2005


Slide 22

doc.: IEEE 802.22-05-0100-00-0000

Submission

Joint maximum power constraint rule in constraint areas

NTSC TV transmitterin Channel N

P = 0P = 0

CPECPE

150 m

P = 0P = 0

P = 0P = 0

P < 4WP < 4W

dmin

4.7 km

d

Grade B

P = 4W if aloneLimit of service provision whenever channel N is occupied by TV operation by this TV station

P = 0P = 0

WRAN BS

P < 4WP < 4W

Joint maximum power constraint rule in this

constraint area

November 2005


Slide 23

doc.: IEEE 802.22-05-0100-00-0000

Submission

Justification of 150 m margin• Calculations show that [2]

A CPE transmitting at 4W with TV operation on channel N should be:• At least 10 m away from noise-protected contour co-channel to DTV operation• At least 150 m away from noise-protected contour on N-1 of DTV operation• At least 44 m away from noise-protected contour on N+1 of DTV operation• At least 4.7 km away from Grade B contour co-channel to NTSC operation• At least 44 m away from Grade B contour on N-1 of NTSC operation• At least 31 m away from Grade B contour on N+1 of NTSC operation

• Thus a 150 m margin beyond the Grade B/noise-protected contours can be given to take care of all but 1 constraints, and would only affect a marginal number of potential WRAN customers.

• An additional margin can be given if needed based on accuracy of distributed sensing measurements, and to take care of outage due to fading.

November 2005


Slide 24

doc.: IEEE 802.22-05-0100-00-0000

Submission

Step by step process for the determination of the interference protection constraints

Spectrum usage map

Table 2 of max powers for all CPEs on all TV bands

List of areas where simultaneous transmissions are criticalList of CPEs in these areas and density of constraint area

Computation of maximum transmit power control rules for the CPEs in each constraint area

Possible set of rules:• dedicated channels to some CPEs (respectively to WRANs)• power control rule as a function of density of CPEs (per constraint area per TV band) below the critical density threshold where communication is not possible or channels cannot be shared by CPEs.• simultaneous scheduling constraints by groups of CPEs within a WRAN

Table 1 of max powers for each CPE on all TV bands Using flowchart #1 and EIRP information

Negotiation between WRANs:• sharing of density and area information• result of negotiation:

• dedicated channels (operating and backup)• shared channels

Power density of other unlicensed users in each constraint area

Distance/location informationIncumbent presence information

Distance and area information

First layer of individual maximum transmit power constraints

Second layer of individual maximum transmit power constraints

Third layer of maximum transmit power constraints

November 2005


Slide 25

doc.: IEEE 802.22-05-0100-00-0000

Submission

Maximum power constraint for a single CPE operation (out-of-band emission mask is assumed to meet the functional requirement 15.1.7 [1])

Table 1 (example)

1st layer of maximum power constraint

2nd layer of maximum power constraint

All values assume a 6 MHz bandwidth used by the CPE. They need to be scaled down later to the bandwidth actually used by the CPE within a TV band.

TV band 7

TV band 6

TV band 5

TV band 4

TV band 3

TV band 2

TV band 1

TV band

CPE operation on

4 W

4 W

4 W

4 W

4 W

4 W

4 W

1No TV

Outside grade BDistance

EIRP(+5)

EIRP(+4)

EIRP(+3)

EIRP(+2)

Not allowed(adjacent band)

Not allowed


2TV

Inside grade B

4 W

4 W

4 W

4 W

4 W

4 W

4 W

3No TV


4 W

4 W

4 W@ 150 m DTV@ 31 m NTSC

4 W @ 10 m DTV@ 4.7 km NTSC


4 W

4 W

4TV


4 WNot allowed4 W4 W

4 WNot allowed(adjacent band)

4 W4 W

4 WEIRP(-2)4 W4 W

4 WEIRP(-3)4 W4 W

4 WEIRP(-4)4 W4 W

4 WEIRP(-5)4 W4 W

4 WEIRP(-6)4 W4 W

8No TV

7TV

Inside grade B

6No TV


5No TV

Inside grade B

TV band 7

TV band 6

TV band 5

TV band 4

TV band 3

TV band 2

TV band 1

TV band

CPE operation on

4 W

4 W

4 W

4 W

4 W

4 W

4 W

1No TV


EIRP(+5)

EIRP(+4)

EIRP(+3)

EIRP(+2)


Not allowed


2TV

Inside grade B

4 W

4 W

4 W

4 W

4 W

4 W

4 W

3No TV


4 W

4 W


4 W @ 10 m DTV@ 4.7 km NTSC


4 W

4 W

4TV


4 WNot allowed4 W4 W

4 WNot allowed(adjacent band)

4 W4 W

4 WEIRP(-2)4 W4 W

4 WEIRP(-3)4 W4 W

4 WEIRP(-4)4 W4 W

4 WEIRP(-5)4 W4 W

4 WEIRP(-6)4 W4 W

8No TV

7TV

Inside grade B

6No TV


5No TV

Inside grade B

CPE Operation not allowed

CPE max transmit power = min{ EIRP(+2), EIRP(-3), 4W }

CPE max transmit power = min{ EIRP(+3), EIRP(-2), 4W }





To Table 2

November 2005


Slide 26

doc.: IEEE 802.22-05-0100-00-0000

Submission

Table 2 (example)

Joint power constraint rule applies whenever CPEs share the same frequency band.

xNot allowedNot allowedTV band 7


xEIRP(+3)EIRP(+3)TV band 5

xEIRP(-3) or power control if not alone(Outside grade B operation at distance d2)

EIRP(-3) or power control if not alone(Outside grade B operation at distance d1)

TV band 4




CPE #3Area #2

CPE #2Contraint Area #1

CPE #1Constraint Area #1

CPE

CPE operation on



xEIRP(+3)EIRP(+3)TV band 5

xEIRP(-3) or power control if not alone(Outside grade B operation at distance d2)

EIRP(-3) or power control if not alone(Outside grade B operation at distance d1)

TV band 4




CPE #3Area #2

CPE #2Contraint Area #1

CPE #1Constraint Area #1

CPE

CPE operation on

Individual or joint maximum power constraint rule might be required

November 2005


Slide 27

doc.: IEEE 802.22-05-0100-00-0000

Submission

Flowchart to determine the first layer of maximum transmit power constraints fill one cell of Table 1

For one given CPE, determine the constraints on all bands incurred by

possible TV operation on band NTV

operation in band

N?

No Yes

CPE in grade B

contour + 150 m?

Distance > 4.7 km?

Max power = 4W

NoYes

Max power = 4W

No Yes

Distance > d_min?

limit max transmit power as a function of

distance

no transmission on channel N

No Yes

DTV or NTSC?

start

CPE in noise-

protected contour +

150 m?

No Yes

• add to list of disallowed bands: N-1, N, N+1• set max power constraint from EIRP(DTV) on other bands

Max power = 4W

Update Table 1

NTSCDTV

November 2005


Slide 28

doc.: IEEE 802.22-05-0100-00-0000

Submission

Simple description of the power rule• A single transmitting CPE induces power at TV receiver:

Where d is the distance of the CPE to the Grade B contour, and a is the path loss exponent. Let n be the density of CPEs in a local area (a few km2).

• Multiple transmitting CPEs: effective path loss exponent is decreasedMaximum transmit power rule:

Power at the nearest TV receiver:

ar tP Pd-=

( ), ar t

CPE constraintareaP P n d d-

Î= å

( ),t tP P n d=

One rule can address interference to incumbent from same and coexisting WRANs given the knowledge of the density of CPEs of all WRANs within a constraint area.

November 2005


Slide 29

doc.: IEEE 802.22-05-0100-00-0000

Submission

3. WRAN MAC


November 2005


Slide 30

doc.: IEEE 802.22-05-0100-00-0000

Submission

MAC Proposals• 802.22 WRAN unique MAC frame structure and messages

– SystemInfo (to carry sensing related information)– BS Communication sub-channel (to provide a ranging and bandwidth

request channel between WRAN base stations)– Modified UL, DL MAP– Additional management message

• BS – CPEs & BS – BS MAC procedures– WRAN initialization and channel sensing– Channel acquisition broadcasting– Sensing reporting– Dynamic frequency selection– Connection management– Inter-WRAN base station management

• Resource partitioning• Dynamic resource renting

November 2005


Slide 31

doc.: IEEE 802.22-05-0100-00-0000

Submission

Basic PHY Architecture (Duplexing)

F2 - Frequency bandF1 - Frequency band

F1 - Frequency bandF1 - Frequency band

Uplink Downlink

TDD

FDD

MAP

Uplink Downlink Uplink Downlink Uplink DownlinkF1

F1 MAP MAP

MAP

Uplink Uplink UplinkF1

F1 MAP MAP

Downlink Downlink Downlink

Time

F2

TDD

FDD

November 2005


Slide 32

doc.: IEEE 802.22-05-0100-00-0000

Submission

Physical frame structureSymbol

Sub-channelPrembles

FCH

Syste

mIn

fo.

DL-M

AP

UL-M

AP

DL Burst # UL Burst #

Symbol

Sub-channel< Up-link >< Down-link >

Cont

rol

Sym

bol

BS C

omm

unica

tion

Sub-

chan

nel

• SystemInfo (in every MAC frame) in BS downlink frame– This portion is used to carry some sensing related information to CPEs/other WRANs– It is also used by BS to send sensing management messages to CPEs or other BSs

• BS communication sub-channel – BS may set BS communication sub-channel periodically; Need not appear in every MAC frame– BS communication sub-channel is used for inter-base station communication– Base station that wants to share some frequency bands must send a request message without collision

November 2005


Slide 33

doc.: IEEE 802.22-05-0100-00-0000

Submission

MAC Frame Structure (Definition of New Portion)

• SystemInfo (in every MAC frame) in BS downlink frame

• Some important fields– CurrentBandList: includes the

currently used bands by the BS– CandidateBandList: includes the

bands that can be used in the case that currently used bands are not available any more

– Sensing Information: includes some commands for CPE sensing

• Quiet time, …

(BandMoveACK)

(Option : ToCPE)

SystemInfo (General) SystemInfoLength

CurrentBandList (Option) CandidateBandList

(Option : ToBS) ToBSType (ResourcePartitionResponse)

(ResourceRentingResponse) (ResourceAllocation) (ResourceCollectionResponse)

(ResourceReturningResponse) ToCPEType (BandChange)

Sensing Information

(ResourceAdvertisement)

(ResourceCollectionACK)

November 2005


Slide 34

doc.: IEEE 802.22-05-0100-00-0000

Submission

MAC Management Message

• Additional message type– SensingReport– BandMoveRequest– BandChangeACK (1:1 case)– ResourcePartitionRequest– ResourceRentingRequest– ResourceRentingACK– ResourceAllocationACK– ResourceCollectionRequest– ResourceCollectionResponseACK– ResourceReturningRequest– ResourceReturningACK

Generic MAC Header ManagementMessage Type Management Message Payload CRC(Optional)

November 2005


Slide 35

doc.: IEEE 802.22-05-0100-00-0000

Submission

3.1 WRAN Initialization (Option 1)

November 2005


Slide 36

doc.: IEEE 802.22-05-0100-00-0000

Submission

3.1 WRAN Initialization (Option 2)• Initialization of WRAN system not simple

– BS consults TV usage database and regional WRAN information base to find potentially empty channels

– BS performs sensing over these channels to check if they are indeed empty– Before using these channels, BS has to get sensing reports from CPEs to enhance channel

occupancy figure– BS broadcasts a “sensing request signal” on channels found empty by it – On receiving sensing request signal on a particular channel, CPEs perform sensing and send a

channel report signal if it finds channel is empty

November 2005


Slide 37

doc.: IEEE 802.22-05-0100-00-0000

Submission

3.2 Channel Acquisition Broadcasting• BS broadcasts a special carrier pattern after it acquires a

channel (every time)– We may use PHY pilots– Easy to detect CR WRAN BS signals by CPEs (simple frequency

scanning)– Let the other BSs know that the channel is already acquired by a

certain CR WRAN BS– Use special carrier signature (each BS may have different signature)

6 MHz 6 MHz

TV in use CR WRAN in use

Acquisitionbroadcasting

November 2005


Slide 38

doc.: IEEE 802.22-05-0100-00-0000

Submission

3.3 Sensing reports when CPEs detect interference• BS performs sensing via collation of detection results from CPEs• Periodic sensing by BS

– BS periodically senses current used bands and other available bands– BS periodically broadcasts some candidate bands with CandidateBandList in

SystemInfo portion• Periodic sensing by CPEs

– BS can request sensing requests to CPEs (periodic, not every frame)• Sensing Information in SystemInfo includes some commands for CPE sensing • If CPE receives the sensing request, it checks whether the current bands and some other

requested bands are available or not• CPE responds with Sensing Report

– Sensing Report = {empty/occupied, (if occupied) licensed incumbent/other WRAN, …}Sensing request (in Sensing Information)Sensing Report

Sensing Information

Sensing Report Sensing Report

Down Frame

UP Frame

Sensing Information

November 2005


Slide 39

doc.: IEEE 802.22-05-0100-00-0000

Submission

State transition diagram for sending CPE sensing reportPeriodic Sensing

Report Start

Random selection of CDMA code

Send the CDMA code with UL

ranging subchannel

Wait for CDMA_Allocation

_IE in UL-MAP

Timeout Tx UL-MAP with CDMA_Allocation_IE

Start Timer Tx

Random BackoffSend sensing report with the allocated data

burst

Done

ReceiveSensing information

.

November 2005


Slide 40

doc.: IEEE 802.22-05-0100-00-0000

Submission

3.4 Frequency Changing by BS• BS should move to new empty bands if a primary system

appears– BS starts frequency sensing. – Before it actually moves to new bands, it should broadcast its frequency

changing to CPEs.• Need a new message (use SystemInfo portion)

– BandChange message– Include up and/or down frequency changing, new frequency info, ….

– CPEs reply with Sensing Report message immediately.• CPE checks (senses) whether the new frequency band is empty or not.• If the new band was already occupied, then it sends a Sensing Report to BS

(with the current up-link band) – BS should wait a sufficient time before it moves.

• Sensing Report may includes– Available Band list (if it has)

• Sensing Report is sent– Piggybacking on the data burst – Request a channel for sensing report (use CDMA codes)

BandChange

Sensing Report Signal from the new band

November 2005


Slide 41

doc.: IEEE 802.22-05-0100-00-0000

Submission

• State transition diagram of frequency changing – BS, CPEStart frequency

sensing

Exist new empty band?

Wait for CPE’s Reply(Sensing Report)

Sudden Death Resolution Procedure

Re-initialization

Broadcast BandChange

Timeout T1

Start Timer T1Yes

No

Sensing Report

SensingReportSuccess/Abort?

Abort

Success

BandChangeCount is MAX?

Need increase Power?(<Max)Increase Power

Yes

Yes

No

No

BandChangeCount+=1

Retry

Wait BandChange

ReceiveBandChange

New frequency band is empty?

SendSensingReport

(Success)

Re-initialization

SendSensingReport

(Abort)

No

Yes

Tiimeout

Attempt to MAX Trial count?

Rendombackoff

No

Yes

Sudden Death Resolution Procedure

November 2005


Slide 42

doc.: IEEE 802.22-05-0100-00-0000

Submission

• Frequency changing failure happens when – CPE does not receive BandChange message – BS did not receive Sensing Report message during the DFS procedure

• Impossible for some CPEs to decode the WRAN BS’s message – if the signal strength from the primary system that suddenly appeared is quite strong

• Sudden death procedure deals with such problems– There will be two possibilities

• First: BS could not recognize the primary system and continuously uses the current bands or BS couldn’t receive the sensing report from CPE during DFS

• Second: BS recognized the primary system appearance. BS will move to new bands (the CPE could not hear BandChange message from BS)

– For both cases, CPEs should search all frequency bands to find out the BS.

WRAN

TV Tx

WRANTV Tx

Frequency Change

3.5 Sudden Death Resolution Procedure

CPE

November 2005


Slide 43

doc.: IEEE 802.22-05-0100-00-0000

Submission

– For the first case, if BS is serving with several bands and the CPE is served with one of the bands of BS, then (FDD case example)

• BS maintains a service table for each CPE– CPE={uplink band, downlink band}

• When the CPE cannot hear BS signal with the current band, it moves to one of the other downlink bands of BS and tries to connect to BS

– After the CPE got a synch with the new band, it sends BandMove message to BS.– BandMove (down2) is sent with the up link band indicated in down2 (in this

example, up2).– BandMoveACK message is sent by BS with the new downlink band (down2)– If CPE cannot receive the BandMoveACK within the given time, it tries to hear

different downlink band.• To do that, BS should broadcast its CurrentBandList in SystemInfo of all

its downlink bands

frequencyup1 up2down1 down2 down3

CPEUplink band problem can be easily detected by BS. BS handles this (e.g., BandChange).

CPE={up1, down1}

CPE={up2, down2}

November 2005


Slide 44

doc.: IEEE 802.22-05-0100-00-0000

Submission

– If CPE fails to synchronize to BS with all current down link bands in the previous CurrentBandList, it may mean that BS changed its service bands into entirely new bands.

• CPE should search all frequency bands until it finds out the BS.

– To reduce this searching effort by CPEs, BS periodically broadcasts some candidate bands to move (BS periodically performs spectrum sensing)

• Candidate bands are not used now, but if BS cannot use the current bands, then it will try to move to the candidate bands first.

• CandidateBandList message is included in SystemInfo portion.• When CPE entirely lost the connection with the BS, then it first searches the BS from the

candidate bands.

frequencyup1 up2down1 down2 down3

CPE

up1

Pre-amble

FCH

UL-MAP

DL - Burst DL - BurstDL - Burst

System Info

DL- MAP

DL - Burst

DL – Burst DL – Burst DL - Burst

MAC frame of down1

CurrentBandList ={down1,down2,down3, up1, up2, up3}

November 2005


Slide 45

doc.: IEEE 802.22-05-0100-00-0000

Submission

• State transition diagram of CPE (sudden death resolution)Detect Sudden

Death

Sync the downlink band in

CurrentBandList

Can be available another downlink band

in CurrentBandList?

Random selection of CDMA code

Send the CDMA code with UL

ranging subchannel

Timeout TxUL-MAP with

CDMA_Allocation_IE

Start Timer Tx

Random Backoff

Attempt to MAX Trial count?

Send BandMove with the allocated

Data Burst

Yes

Exist available band in CandidateBandList?

Search all frequency bands

No

Sync the downlink band in

CandidateBandList

Is band allocated?

Re-initialization?Or Done

Yes

Yes

Wait for CDMA_Allocation

_IE in UL-MAP

Is MAP Information available in the CandiateBand?

No

Yes

No

Yes

No

No

Wait for BandMoveACK

Start Timer Tx Timeout Tx Allocation ACK Re-initialization

November 2005


Slide 46

doc.: IEEE 802.22-05-0100-00-0000

Submission

3.6 Resource Partition Request by other BSs• Network environment

– Multiple WRAN service providers (Base Stations) may need to share available resources• One BS (prior BS) already acquired TV channels, and if other BSs cannot

secure the required resource (additional TV bands are not available)– Other BSs can request a resource partition to the prior BS

• Using a special sub-channel or slot of the prior BS’s UP link• Resource partition ratio between different BSs is outside of this proposal

(pre-determined)

DownlinkRPREQ(Uplink)

Prior BS

RPREP(Downlink)

New BS

November 2005


Slide 47

doc.: IEEE 802.22-05-0100-00-0000

Submission

• MAC frame structure for resource partition request– For OFDMA PHY: define BS Communication Sub-channel– BS Communication Sub-channel does not appear in every frame,

• BS communication sub-channel appearance and symbol length is defined in UL-MAP

• BS communication sub-channel appears periodically but not in every frame

DL - BurstDL –

BurstDL – Burst

DL - BurstDL- MAP

DL - Burst

DL - Burst

DL - BurstUL-

MAP

FCH

Ranging Subchannel

UL- Burst

UL- Burst

UL- Burst

UL- Burst

UL- Burst

Prea

mbl

e

OFDMA symbol number

Subc

hann

el lo

gica

l num

ber

System Info

BSCommunication_IEBSCommunication Sub-

channel

Downlink Uplink

November 2005


Slide 48

doc.: IEEE 802.22-05-0100-00-0000

Submission

– Each BSs should be able to send the resource partition requests to the prior BS without (or little) collisions

– And, the resource partition requests sent by other BSs should be treated with higher priority than ranging or bandwidth requests sent by CPEs of the prior BS

• BS Communication Sub-Channel (OFDMA case)B

S C

omm

unic

atio

nSu

bCha

nnel

Ranging and BW requests from CPEs of the prior BS

Prior BS UP LinkOFDM symbol

sub-channelnumber

Each BS selects one of possible CDMA

codes; because the number of BSs is

small, there will be little collisions

UL-Burst

November 2005


Slide 49

doc.: IEEE 802.22-05-0100-00-0000

Submission

• State transition diagram of resource partition request – Other BSs

Wait for BSCommunication

Domain

UL-MAP with BSCommunicat

ion_IE

Selection of CDMA codes(128)

Resource PartitionRequest

Start Timer T3

Wait Resource PartitionResponse

Timeout T3

Wait for BSCommunication

Domain

Resource PartitionResponse

Resource Partition

SendRanging Code

Wait for CDMA_Allocation_IE

in UL-MAP

UL-MAP with CDMA_Allocatio

n_IE

November 2005


Slide 50

doc.: IEEE 802.22-05-0100-00-0000

Submission

Prior BS

Send UL-MAP without BSCommunication_IE

[Time to send next map]Send UL-MAP containing BSCommunication_IE

[Receive CDMA code]Send UL-MAP containing CDMA_Allocation_IE

[Receive RPREQ]Send RPREP

[Time to send next map]Send UL-MAP

New BS

Wait

Confirm whether BSCommunication_IE exists

Transmit randomly selected CDMA code in BSCommunication Sub-Channel

Send RPREQ

UL- MAP

UL- MAP

UL- MAP

RPREP

UL- MAP

CDMA code

RPREQ

• Message flows of resource partition request

November 2005


Slide 51

doc.: IEEE 802.22-05-0100-00-0000

Submission

3.7 Dynamic Resource Renting Procedure• One regional area, multiple BSs share available resources

– Resource partition ratio between BSs is usually fixed based on agreement• Example : BS1 (50%), BS2(50%)

• However– The number of subscribers of each service provider may be different– The total traffic volume of each BS is also different and time varying

• Dynamic resource renting procedure between BSs1) Offeror broadcasts its unused resource in terms of (subchannels and time

slots in a frame)2) Renter requests its desired resource and duration3) Offeror broadcast its allocation4) Renter sends an ACK5) Renter may return the borrowed resource before the rental time ends6) Offeror may collect the resource before the rental time ends

November 2005


Slide 52

doc.: IEEE 802.22-05-0100-00-0000

Submission

• Resource definition for rent: Resource Advertisement message in SystemInfo portion – OFDMA case: (sub-channels, symbol number (time))

• Rent request by other BSs– Use offeror BS’s UP link channel

• OFDMA case: BS communication sub-channel

FCH

UL-MAP

DL - Burst DL - Burst

DL - Burst

System Info

DL- MAP

DL - Burst

DL – Burst(resource for renting)

DL – Burst(resource for

renting)

DL - Burst

Resource AdvertisementMAC message

(format and syntax)To be determined

Offeror Down Link Offeror UP Link

Renter BS sends a CDMA code with offeror’s UL ranging subchannel to be allocated for resource

BS

Com

mun

icat

ion

SubC

hann

el

UL-BURST

UL-BURST

UL-BURST

UL-BURST

UL-BURST

UL-BURST

November 2005


Slide 53

doc.: IEEE 802.22-05-0100-00-0000

Submission

• Renting Procedure

• Collecting Procedure

• Returning procedure

ResourceAdvertisement

Offeror

Renter

Resource Renting Request

ResourceRenting Response

Resource Renting ACK

Offeror DL(SystemInfo)

Offeror UL

Offeror

Renter

ResourceCollection Request

Resource Collection Response

ResourceCollection Response ACK

ResourceCollection ACK

Renter ULRenter DL(SystemInfo)

Resource AdvertisementResource Renting Request

Resource Renting ResponseResource Renting ACK

Resource Collection RequestResource Collection Response

Resource Collection Response ACKResource Collection ACK

To be determined

Offeror

Renter

ResourceReturning Request

ResourceReturning Response

ResourceReturning ACK

Offeror DL(SystemInfo)

Offeror ULResource Returning

RequestResource Returning

ResponseResource Returning ACK

To be determined

November 2005


Slide 54

doc.: IEEE 802.22-05-0100-00-0000

Submission

• For communication between WRAN BSs – When a BS sends its messages using other WRAN BS’s uplink

channel, the BS should request other BS’s up link resource first– Example scenario

• BS1 periodically (need not in every frame) broadcasts the appearance of BS Communication sub-Channel and its position in UL-MAP with BS1’s downlink

• If BS2 wants to send a message to BS1, BS2 decodes BS1’s UL-MAP to see if the next up link channel of BS1 BS Communication sub-channel is available

• BS2 sends a CDMA code in BS Communication sub-channel of BS1’s up link

• BS1 allocates up link resource to BS2 with UL-MAP• BS2 sends a message for the dynamic resource renting procedure

November 2005


Slide 55

doc.: IEEE 802.22-05-0100-00-0000

Submission

4. WRAN PHY


November 2005


Slide 56

doc.: IEEE 802.22-05-0100-00-0000

Submission

Overview of OFDMA• A variation on OFDM• Multiple access is realized by providing each user with a fraction

of the available number of subcarriers• OFDMA avoids the relatively large guard bands necessary in

FDMA to separate different users

TX#4TX#3

TX#2

TX#6

TX#5

TX#1

Time

Freq

uenc

y bi

n

2468

1012141618202224262830

00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

November 2005


Slide 57

doc.: IEEE 802.22-05-0100-00-0000

Submission

System parameters

• Basic parameters– FFT Size : 1024, 2048, 4096– Coding : Convolutional Turbo Codes– Modulation : QPSK, 16QAM, 64QAM– Channel BW : 6, 7, 8 MHz (TV band)– Operation Channel : Single or Multi Channel– Duplexing Mode : Full duplex FDD and TDD system

November 2005


Slide 58

doc.: IEEE 802.22-05-0100-00-0000

Submission

WRAN physical layer parameters# of subcarrier 1 K mode 2 K mode 4 K mode

Subcarrier spacing(KHz)

6MHz 5.860 2.930 1.464

7MHz 6.863 3.418 1.7090

8MHz 7.813 3.906 1.9531

Effective Subcarrier864

(null carrier : left 80, right 79,DC 1)

1728(null carrier : left 160,right 159,

DC 1)

3408(null carrier : left 343, right

344, DC 1)

FFT duration

(s)

6MHz 170.66 341.33 682.66

7MHz 145.71 292.57 585.14

8MHz 127.99 256.01 512.00

Duration of GI (s)

6Mhz 35.165 60.164 35.165 60.164 35.165 60.164

7Mhz 35.145 60.04 35.145 60.04 35.145 60.04

8Mhz 35.122 60.245 35.122 60.245 35.122 60.245

Symbol Duration

(s)

6MHz 204.792 230.67 375.463 401.33 716.793 742.66

7MHz 180.86 205.75 327.71 352.61 620.285 645.18

8MHz 163.11 188.235 291.13 316.255 547.122 572.245

November 2005


Slide 59

doc.: IEEE 802.22-05-0100-00-0000

Submission

TDD• TDD parameter define(6MHz case)

Parameter Value

Duplex TDD

Multiple Access OFDMA

System Bandwidth 6 MHz

Sampling frequency 6 MHz

1K mode 2K mode 4K mode

Number of used tones 864 out of 1,024 1728 out of 2,048 3,456 out of 4,096

Number of data tones 768 1536 3,072

Number of pilot tones 96 192 384

Tone spacing 5.859375 kHz 2.9296875 kHz 1.46484375 kHz

Signal bandwidth 5.0625 MHz 5.0654 MHz 4.9921875 MHz

FFT duration 170.67 μs 341.33 μs 682.66 μs

Cyclic prefix time 35.165 μs 60.1642 μs 35.165 μs 60.1642 μs 35.165 μs 60.1642 μs

OFDMA symbol time 204.792 μs 230.67 μs 375.463 μs 401.33 μs 716.793 μs 742.66 μs

TDD frame length 4 ms 5 ms 6 ms 4 ms 5 ms 6 ms 4 ms 5 ms 6 ms

Number of symbols in a frame 19 24 29 10 13 15 5 6 8

November 2005


Slide 60

doc.: IEEE 802.22-05-0100-00-0000

Submission

TDD• TDD Time duration parameter (6MHz case)

Frame structure (ref: duty ratio 1:1 / 2:1 / 3:1)

1K mode 2K mode 4K mode

DL UL DL UL DL UL

Timeduration

Tx duration (TTrans)

4ms1.843/2.253

/2.662 ms

1.638/1.228/

0.819 ms- - - -

5ms2.252/3.072

/3.481 ms

2.252/3.891

/4.301ms

2.252/-/-

2.252.778/-/-

- -

6ms

2.867/3.891/4.301

ms

2.662/1.638/1.229

ms

3.003/3.755/4.130

ms

2.628/1.877/1.502

ms

2.867/3.584

ms

2.150/1.434

Ms

TDD Gap time (Tguard)

4ms 518.536 μs(288.90+129.63) - -

5ms 494.58 μs(370.9+123.64)

494.44 μs(370.83+123.61) -

6ms470.616μs

(TTG + RTG = 353.025μs + 117.675 μs)

368.055μs(TTG + RTG =

273.000μs + 92.000 μs)

982.449 μs(TTG + RTG =

736.500μs + 245.500 μs)

November 2005


Slide 61

doc.: IEEE 802.22-05-0100-00-0000

Submission

TDD Frame Structure

Frame #1 Frame #2 Frame #n● ● ● ●

QTSuper Frame #n● ● ● ● Super Frame #1

Preamb

le

FCH / Broadcast

MSGDL PHY PDU (SS#1- SS#n) TTG

initial Ranging

BW reques

t

UL PHY PDU(SS#1-SS#n) OFDMA StructureRTG

DL

MAP

UL

MAP

TTG

BIN

AMC SSTMST TTG

Cluster

RTG

Syst

em in

fo

Band 0

Band 1

Band 2

Band 3

Band B-1

Band B-2

...

...

...

...

...

...

Prea

mbl

e

...............

...

...

...AMC Tile

FCH

RTG

ControlSymbol

TileBIN

... ...

Down Link Up Link

BS c

omm

unic

atio

n

QT

Super Frame #2QT Super Frame #1

November 2005


Slide 62

doc.: IEEE 802.22-05-0100-00-0000

Submission

FDD• 1K /2K / 4K mode FDD parameter define

Parameter 1K 2K 4K

Duplex FDD

Multiple Access OFDMA

System Bandwidth 6MHz

Sampling frequency 6MHz

Number of used tones 864 of 1,024 1728 out of 2,048 3408 out of 4,096

Number of data tones 768 1536 3024

Number of pilot tones 96 192 384

Tone spacing 5.859375KHz 2.9296875 kHz 1.46484375 kHz

Signal bandwidth 5.0625MHz 5.0654 MHz 4.9921875 MHz

Basic OFDMA symbol time 170.67 μs 341.33 μs 682.66 μs

Cyclic prefix time 34.134 μs 34.133 μs 34.133 μs

OFDMA symbol time 202.804 μs 375.463 μs 716.793μs

TDD frame length 3 / 4 / 5 / 6 ms 3 / 4 / 5 / 6 ms 3 / 4 / 5 / 6 ms

Number of symbols in a frame

14 / 19 / 24 / 29 7 / 10 / 13 / 15 4 / 5 / 6 / 8

November 2005


Slide 63

doc.: IEEE 802.22-05-0100-00-0000

Submission

FDD Frame Structure

Down Link Frame Structure

UP Link Frame Structure

Super Frame #1


QTSuper Frame #m● ● ● ● Super Frame #1

3ms ~ 6ms

Preamble FCH / Broadcast MSG DL PHY PDU (SS#1- SS#n)

PUSC

Cluster

Band 0

Band 1

Band 2

Band 3

Band B-1

Band B-2

Prea

mbl

e

BIN

MST SST

............

...

...

...............

...

...

...

FCH

DL

MAP

UL

MAPSysInfo.

QT

QT Super Frame #2

ContentionSlot for initial

Rangin BW

requestUL PHY PDU(SS#1-SS#n) OFDMA Structure


QTSuper Frame #n● ● ● ● Super Frame #1

AMC Tile

ControlSymbol

TileBIN

...

............

BS

com

mun

icat

ion

Super Frame #2

QT

Super Frame #1QT

November 2005


Slide 64

doc.: IEEE 802.22-05-0100-00-0000

Submission

System Capacity• TDD / FDD capacity comparison• Whole Frame Capacity• 1 frame duration – TDD : 6ms / FDD : 3ms, single symbol transmission case unit : Mbps

FFT Size 1K 2K

ModulationDL 　 UL 　 DL UL

TDD FDD TDD FDD TDD FDD TDD FDD

Q P S K

1 / 2 3.242077

3.750146

3.525086

3.750146

3.461697

4.090949

3.854812

4.090949

2 / 3 4.322769

5.000195

4.700115

5.000195

4.615596

5.454599

5.139749

5.454599

3 / 4 4.863116 5.62522 5.28763 5.62522 5.19254

66.13642

45.78221

86.13642

4

7 / 8 5.673635

6.562756

6.168901

6.562756 6.05797 7.15916

16.74592

17.15916

1

16QAM

1 / 2 6.484154

7.500293

7.050173

7.500293

6.923394

8.181898

7.709624

8.181898

2 / 3 8.645539

10.00039 9.40023 10.0003

99.23119

2 10.9092 10.2795 10.9092

3 / 4 9.726231

11.25044

10.57526

11.25044

10.38509

12.27285

11.56444

12.27285

7 / 8 11.34727

13.12551 12.3378 13.1255

112.1159

414.3183

213.4918

414.3183

2

64QAM

1 / 2 9.726231

11.25044

10.57526

11.25044

10.38509

12.27285

11.56444

12.27285

2 / 3 12.96831

15.00059

14.10035

15.00059

13.84679 16.3638 15.4192

5 16.3638

3 / 4 14.58935

16.87566

15.86289

16.87566

15.57764

18.40927

17.34665

18.40927

7 / 8 17.0209 19.68827 18.5067 19.6882

718.1739

121.4774

820.2377

621.4774

8

November 2005


Slide 65

doc.: IEEE 802.22-05-0100-00-0000

Submission

5. Other considerations on WRAN PHY and MAC

• Solutions to address requirements in the following sections of the FRD– General requirements of Sections 5 and 15.

November 2005


Slide 66

doc.: IEEE 802.22-05-0100-00-0000

Submission

5.1. WRAN Pilot

• Relevant sections of the Functional Requirements Document [1]

5.5.1: The base station SHALL serve as a radio resource supervisor and controller for its “cell,” including all associated CPEs and/or optional repeaters, if implemented, in its cell. A Master/Slave relationship between the base station and the CPEs SHALL be established whereby all the RF characteristics of the CPEs are remotely controlled by the base station.

• The proposal of including RACH channel ID guarantees the reliability of Channel Sensing and Initialization described in Section 3.1 in this document.

November 2005


Slide 67

doc.: IEEE 802.22-05-0100-00-0000

Submission

WRAN Pilot

• Pilot definition (in terms of function)– Frequency synchronization (sync LO)– Cell timing synchronization (sync timing)– WRAN ID and BS ID (cell identification)– RACH ID (UL transmission, mandatory for FDD, optional for

TDD)

• For a fresh-started CPE to be able to start the first transmission, the BS must include in its pilot the information of the channel ID of the reverse access channel (RACH).

November 2005


Slide 68

doc.: IEEE 802.22-05-0100-00-0000

Submission

5.2. Smart antenna for sensing, cell searching, packet transmitting and

receiving, and soft combining.• Relevant sections of the Functional Requirements Document [1]

– 5: The base station radio SHALL be P-MP, capable of radiating its downstream signal (forward) toward the CPEs with an omni-directional, a shaped sector, or optionally an adaptive array (spatial reuse) antenna achieving broad azimuthal beam width to serve a number of prospective subscribers.

– 15.1.1.7: The base station and the CPEs SHALL sense licensed transmissions using an omni-directional antenna with a gain of 0 dBi or greater (where all losses between the antenna and the input to the receiver are included) in any azimuthal direction and polarization.

November 2005


Slide 69

doc.: IEEE 802.22-05-0100-00-0000

Submission

• Sensing: omni, 0dBi

• Cell searching: Beamforming (one beam, but space-sweeping), highest gain:

• Packet transmitting and receiving: Beamforming (one fixed beam), highest gain

• Soft combining: Beamforming (multiple beams), highest gain

BS

BS

November 2005


Slide 70

doc.: IEEE 802.22-05-0100-00-0000

Submission

5.3. Spectrum Classification at BS

• Relevant sections of the Functional Requirements Document [1] 15.1.4: The system SHALL provide a way to populate a table of

channels that characterizes channel availability – such as disallowed, occupied, available, available at reduced power , etc., and to update that table at any time. The base station, and optionally the CPEs, SHOULD maintain a "list" of backup channel(s) in case a new incumbent is detected and a channel has to be quickly vacated. The exact scheme can be left to the proposers, as different approaches could be suggested to address this issue.

• The proposal of spectrum classification at BS make it smoother and more reliable of the Frequency Changing described in Section 3.4 in this document.

November 2005


Slide 71

doc.: IEEE 802.22-05-0100-00-0000

Submission

Spectrum Classification (State transitions)

Active SetCandidate SetObserving SetDisallowed Set

C/I < S1 C/I < S2 Needed

C/I > S1

C/I > S2

C/I > S1

C/I > S1Frequency Changing

November 2005


Slide 72

doc.: IEEE 802.22-05-0100-00-0000

Submission

5.4. WRAN Coexistence (Spectrum Etiquette)

• Relevant sections of the Functional Requirements Document [1] 15.2.1: Systems SHALL have means to coordinate with each other to

facilitate sharing, coexistence, and interference mitigation amongst neighbors.

• The proposal of spectrum etiquette is for inter-WRAN coexistence. It is an alternative of the Dynamic Resource Renting Procedure described in Section 3.7 in this document.

November 2005


Slide 73

doc.: IEEE 802.22-05-0100-00-0000

Submission

Spectrum Etiquette (Definitions)• We are proposing a distributed interference-management scheme. Hence,

the central sector/cell and neighbor sectors/cells are relative concept. If there is no sectorization, one central cell has 6 neighbor cells. The scheme is illustrated using a 6-sector per cell scenario.

• Fusable, ID := the frequencies that won’t interfere incumbent uses.• Fused, ID := the frequencies that the central sector has picked up. This could

include some backup frequencies.• Fpool := the frequencies that are usable and are not used by neighbor cells :=

Fusable, ID \ (Fused,n1 U Fused,n2 U Fused,n3)• Flocal := Fpool \ {Fusable,n1 U Fusable, n2 U Fusable, n3}

• Notes: – symbols U, ∩, and \ mean union, intersection, and exclude. – ID means the sector ID. Neighbor sectors are further denoted as n1, n2, and n3.

November 2005


Slide 74

doc.: IEEE 802.22-05-0100-00-0000

Submission

Spectrum Etiquette (Procedure)1. The central sector decides its Fusable, and Fpool.2. The central sector picks up frequencies from the Fpool according to

the following etiquette principles.i. Try to the frequencies that won’t be used by neighbor cells at all. In

other words, use first the frequencies in Flocal

ii. If the central sector is satisfied, go to Step 3. Otherwise, try to pick up frequencies from the rest of Fpool with the consideration of avoid using the frequencies that will affect a single neighbor cell most. For example, Use first the frequencies that are not shared by more than one neighbor cells, then other frequencies that may affect more and more neighbor cells.

iii. If the central sector is satisfied, go to Step 3. Otherwise, go back to Step 1 and try later. (an optional step can be taken here is trying to ask help from neighbor cells so they could release some frequencies.)

3. If needed, update neighbor cells of its Fusable, and Fused. Go back to Step 1.

Note: the procedure can be done periodically, or can be triggered by a certain predefined events.

November 2005


Slide 75

doc.: IEEE 802.22-05-0100-00-0000

Submission

Example

N3: 1,4,8

N2: 1,5,6

N1: 1,2,3

1,3,4,6,7

Neighbor 1 Neighbor 2 Neighbor 3 Central

Fusable 1,2,3 1,5,6 1,4,8 1,3,4,6,7

Fused 2 5 8

Fpool 1,3,4,6,7

1st Selection 7

2nd Selection 4 (randomly from 3,4,6)

Final Selection 3 (randomly from 3,,6)

November 2005


Slide 76

doc.: IEEE 802.22-05-0100-00-0000

Submission

5.5. Coexistence with other LE systems (Contention-Based Protocol)

• Relevant sections of the Functional Requirements Document [1] 15: Furthermore, these protocols SHALL also include means to allow

coexistence among multiple WRAN systems and with other license-exempt systems in these bands for fair and efficient use of the spectrum.

November 2005


Slide 77

doc.: IEEE 802.22-05-0100-00-0000

Submission

DL Contention-Based Coexistence with LE Devices (Call Flow)

CPE Primary BS

Detect LE devices

Normal data transmitting

Data transmitting in contention manner

Contention needed

Contention

November 2005


Slide 78

doc.: IEEE 802.22-05-0100-00-0000

Submission

UL Contention-Based Coexistence with LE Devices (Call Flow)

CPE Primary BS

Detect LE devices

Contention needed

Normal data transmitting

Contend with LE at the next TXOP

Data transmitting in contention manner

November 2005


Slide 79

doc.: IEEE 802.22-05-0100-00-0000

Submission

5.6. Soft Combining

• While it is not required in FRD, Soft Combing does have the following advantages:– Extend coverage: Multiple BSs work together and support edge

CPEs– Reduce interference: Neither BSs nor CPE needs to increase

power in order to support a certain data rate.– It is very possible for OFDM-based WRAN given the fixed P-MP

topology.

November 2005


Slide 80

doc.: IEEE 802.22-05-0100-00-0000

Submission

Soft-combining Call Flow (DL)

CPE Primary BS Supportive BS

SC Req. (S-BS ID)SC Req.

Ranging

SC Accepted

Data

Data

Data

November 2005


Slide 81

doc.: IEEE 802.22-05-0100-00-0000

Submission

Soft-combining Call Flow (UL)

CPE Primary BS Supportive BS

SC Req. (S-BS ID)SC Req.

Ranging

SC Accepted

DataData

Data Extraction

November 2005


Slide 82

doc.: IEEE 802.22-05-0100-00-0000

Submission

5.7. Flexible CPE Operation Modes

• This is not a scheduling issue, rather an issue on system flexibility.

• CPEs of different categories can satisfy different customers. For example, SME and SOHO customers may want to pay for more expensive CPEs than a regular home owner would do.

• We propose the procedure for supporting various categories of CPEs. For example,

– CPEs with various bandwidth: 1.25 MHz, 2.5 MHz, 5 MHz, 6 MHz or 20 MHz. – CPEs with different service level agreements.

• BS perspective: there are several groups of CPEs, each with a certain bandwidth.

• CPE perspective: multiple channels are available from BS

November 2005


Slide 83

doc.: IEEE 802.22-05-0100-00-0000

Submission

Procedures• Initial acquisition

– CPE send the request of bandwidth and service level agreement.– BS assigns the CPE a bandwidth based on the SLA and

availability of system resources.• CPE scans other spectrum under the direction of BS, reports back

channel condition information (CQI) and the request for channel change.

• If it is beneficial for the CPE and other users, BS confirms the center frequency that user should tune into, based on the CQI feedback, user profile, and SLA.

• CPE may repeat Steps 2 and 3 occasionally, e.g., when the link conditions in the current channel deteriorates.

• Besides the request from CPE, BS may inform CPE to tune into a different channel for load balancing or other purposes (e.g., strategic sensing).

• Dependent on other users’ profile and the SLAs, BS may reserve a certain frequencies for higher priorities applications and for users with higher privilege.

November 2005


Slide 84

doc.: IEEE 802.22-05-0100-00-0000

Submission

References

• [1] Functional Requirements for the 802.22 WRAN Standard, doc.: IEEE 802.22-05/0007r46 .

• [2] WRAN Reference Model, doc.: IEEE 802.22-04/0002r12.

doc.: ieee 802.22-05-0100-00-0000 submission november 2005 ashish pandharipande, saitslide 1...

Documents