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doc.: IEEE 802.22-11/0130r1

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IEEE 802.22 MAC/CC Overview

Nov. 2011

Gwangzeen Ko, ETRISlide 1

IEEE P802.22 Wireless RANs Date: 2011-11-02

Name Company Address Phone email Gwang-Zeen Ko ETRI Korea +82-42-860-4862 [email protected]

Byung Jang Jeong ETRI Korea +82-42-860-6765 [email protected]

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

Jung-Sun Um ETRI Korea +82-42-860-4844 [email protected]

Antony Franklin ETRI Korea +82-42-860-0752 [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 that the draft publication will be approved for publication. Please notify the Chair Apurva Mody <[email protected]> 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].

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Abstract

This contribution summarizes the MAC and Cognitive Capability (CC) features in the IEEE 802.22-2011 Standard.

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Contents• 802.22 MAC Features

– Introduction – Super-frame/Frame Structure– CBP summary and Coexistence schemes

• Dynamic QP Scheduling• Self-Coexistence Schemes

• Cognitive Capabilities in 802.22– Spectrum Manager– Channel Classification– Spectrum Sensing– Geo-location– DB Access

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MAC Introduction (1)• Some aspects of IEEE 802.22-2011 MAC have been inspired from

the IEEE 802.16 MAC standard• Combination of polling, contention and unsolicited bandwidth

grants mechanisms• Support of Unicast/Multicast/Broadcast for both management and

data• Connection-oriented MAC

– Connection identifier (CID) is a key component• IEEE 802.22-2011 CID can be constructed from Station ID (SID) and Flow

Identifier (FID) [1]. This new CID definition can reduce overhead and storage requirements [2].

– Defines a mapping between peer processes– Defines a service flow (QoS provisioning)

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MAC Introduction (2)

• However, major enhancements have been made– Support of Cognitive functionality

• Dynamic and adaptive scheduling of quiet periods• Various incumbent user detection and notification methods

– Coexistence with both incumbents and other 802.22 systems (self-coexistence)

• Measurements (incumbents and 802.22 operation)• Spectrum management (time, frequency and power)• The Coexistence Beacon Protocol (CBP)• The Incumbent Detection Recovery Protocol (IDRP)• Wireless microphone beacon mechanism (IEEE 802.22.1)

– Self-coexistence mechanisms• Spectrum Etiquette• On-demand Frame Contention

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

frame 0

Superframe Preamble SCH

frame Preamble

frame 1

Superframe Preamble

SCHframe Preamble

frame 15

frame Preamble

WRAN 0

WRAN 1

......

......

160 ms

10 ms

Time

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

...

FramePreamble FCH DS burst 1 DS burst 2 DS burst x...

UDCOptionalBroadcastMAC PDU

MAC PDU 1 ... MAC PDU y Pad

MAC Header MAC Payload CRC

Ranging slots

BW request slots

US Burst (CPE m)

US PHY PDU (CPE p)

...

MAC PDU 1 ... MAC PDU k Pad

MAC Header MAC Payload CRC

UCS Notification

Slots

DS subframe

US-MAPDS-MAP DCD

US subframe

TTGSelf Coexistence

Window RTG

Nov. 2011


IEEE 802.22 Frame Structure(Logical View)

Super frame Structure

Frame Structure

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IEEE 802.22 Frame Structure(Physical View)

DS sub-frame TTG

RTG

US sub-frame(smallest US burst portion on a given subchannel= 7 symbols)

26 to 42 symbols corresponding to bandwidths from 6 MHz to 8 MHz and cyclic prefixes from 1/4 to 1/32Fr

ame

Prea

mbl

e

FCH

DS-

MA

P

Burs

t 1DCD

Burs

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ffer

Self

-coe

xist

ence

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r 5

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n sc

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led)

Burst 1

60 s

ubch

anne

ls

Burst 2

Burst 3more than 7 OFDMA symbols

Burst

Burst n

Burst

Burs

t m

Ranging/BW request/UCS notification

Burst

Burst

Bursts

Burs

ts

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

10 ms

US-

MA

P

US-

MA

PU

CD

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Concept of 802.22 Frame Operation

The allocation of burst could be based on distance of CPE

from BS in order to compensate the delay

of arrival

Contention for all CBP transmitters

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SCH and CBP Features

• The Super-frame Control Header (SCH)– Provides the control information for a WRAN cell– Support the intra-frame and inter-frame quiet periods management mechanisms

for sensing– Support coexistence with incumbents and other WRAN cells (self coexistence)

• An SCH can include various CBP (Coexistence Beacon Protocol) IEs– Backup channel information IE– Frame Contention information IE– Terrestrial Geo-location information IE– Signature IE, Certificate IEs (CBP frame security)

• Using SCH, WRAN BS can intelligently manage the operation of its associated CPEs

• Also, using CBP (Extended version of SCH), WRAN BS can intelligently manage the operation of neighboring WRAN cell under co-existence situation

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CBP Summary• CBP is used to communicate the operating parameters from one

WRAN cell to another WRAN cell• CBP packet is transmitted using SCW which contains the SCH of

its own WRAN cell• CBP is fully controllable by the BS that decides who sends/listens

and when to send/listen for CBP packets (Refer [3])– The source of a CBP packet can be either a BS or a CPE

• CBP packets carry only control information (no data)

Structure of a CBP packet

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Dynamic Quiet Period Scheduling

Intra-Frame QP scheduling(Some part of super-frame)

QP < 1Frame

Intra-Frame QP scheduling(Some part of super-frames)

QP = 1 Frame

Inter-Frame QP scheduling(whole super-frame except SCH)

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Self-Coexistence Mechanism (1)• Self-Coexistence: Co-existence among WRAN Systems [4]

(Exchange of information between BSs through CPEs using the self-coexistence window)

Coexistence beacon protocol

On-

dem

and

fram

eco

nten

tion

Spec

trum

etiq

uette

Orthogonal channel selection for operating channel and first

backup channel

Frame allocation signalledby the super-frame control

header (SCH)

MAC self-coexistence schemes PHY coexistence mechanisms

Enough channels available

Two or more cells need to coexist on the same channel

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Self-Coexistence Mechanism (2)• Spectrum Etiquette [4]

• Orthogonal channel assignment scheme between adjacent cells– different operating channel for overlapping or adjacent cells– different first backup channel

1, 2, 7 3, 4, 2, 6, 7

5, 6, 2, 7, 84, 8, 2, 6, 7

3, 7, 2, 5, 8

6, 4, 2, 5, 7 8, 5, 2, 4, 7

7, 5 3, 4, 6

5, 6, 2, 84, 8, 2, 6

3, 2, 5, 8

6, 4, 2, 5 8, 5, 2, 4

1 2

Requires that information on operating, backup and candidate channelsof each cell is shared amongst WRAN cells: exchanged by CBP packets [5]

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Self-Coexistence Mechanism (3)• On-demand Frame Contention

• Two or more cells need to co-exist on the same channel

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Cognitive Capability

• Collection of Spectrum Information– Geo-location information (A)– TVWS Database (B)– CPE Spectrum Sensor (C)– BS Spectrum Sensor (D)

• Cognitive Engine (Decision Maker)– Spectrum Manager (BS)– Spectrum Automation (CPE)

• Configurable Communication System – 802.22 PHY– 802.22 MAC

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Summary of Spectrum Manager [4]

Spectrum Manager

Policies

Incumbent Database Service

IncumbentDatabase

Spectrum SensingRF sensing performance

0.1%

1.0%

10.0%

100.0%

-26 -24 -22 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2SNR (dB)

Prob

abilit

y of m

isdete

ction

(Pmd

)

Energy - 1dB Pfa=10% 5 ms

Energy - 0.5dB Pfa=10% 5 ms

Energy - 0dB Pfa=10% 5ms

Thomson-Segment Pfa=10% 4 ms

I2R Pfa=0.1% 4ms

I2R Pfa= 1% 4ms

I2R Pfa=10% 4 ms

Qualcomm Field Pfa=10% 24 ms

Qualcom Field Pfa=1% 24 ms

Thomson Field Pfa=10% 24 ms

Thomson Field Pfa=1% 24ms

Channel Set Management Subscriber Station Registration and Tracking

Self Co-existenceGeo-location

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SM Channel Classification [5]Two step channel decision

External to IEEE 802.22 System

Internal to IEEE 802.22 System

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Spectrum Sensing[6]

• IEEE 802.22 supports spectrum sensing capability by using SSA and SSF• Spectrum Sensing Automation (SSA, sensing manager)

– All the IEEE 802.22 devices (BS and CPEs) shall also have an entity called the Spectrum Sensing Automaton (SSA). The SSA interfaces to the Spectrum Sensing Function (SSF) and executes the commands from the SM to enable spectrum sensing

• Spectrum Sensing Function (SSF, sensor)– Spectrum sensing is the process of observing the RF spectrum of a television

channel to determine its occupancy (by either incumbents or other WRANs).– The base station and all CPEs shall implement the Spectrum Sensing Function

(SSF)– The SSF shall be driven by the SSA. The SSF shall observe the RF spectrum of

a television channel and shall report the results of that observation to the SM (at the BS) via its associated SSA

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Spectrum Sensing [6]

Spectrum Sensing Automation state machine Input/Output of the Spectrum Sensing Function

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Geo-Location• Satellite based geo-location [7]

– Requires GPS antenna at each device– NMEA 0183 data string used to represent geo-location– Poor accuracy in Northern hemispheres

• Terrestrial based geo-location [4]– Besides satellite-based geo-location, the 802.22 standard includes terrestrial

geo-location using inherent capabilities of the OFDM based modulation and the coexistence beacon protocol bursts transmitted and received among CPEs

– Propagation time measured between BS and its CPEs and among CPEs of the same cell using Fine Time Difference of Arrival: TDOA

BS Vernier-1

Vernier-2

CPE1

Downstream

Upstream

Vernier-3CPE

2

CBP burst

Vernier-1

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DB Access• WRAN DB access [6]

– 802.22 WG defined DB access structure– Interfaces are defined between DB and BS

• Defined number of primitives for DB access

– M-DB-AVAILABLE-REQUEST– M-DEVICE-ENLISTMENT-REQUEST– M-DB-AVAILABLE-CHANNEL-

REQUEST– M-DB-AVAILABLE-CHANNEL-

INDICATION– M-DB-DELIST-REQUEST– Etc.

Structure of the IEEE 802.22 WRANaccess to the database service

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References

[1] “Additional text to implement new connection identifier management approach”, 22-10-0137-02-0000, Aug. 2010.

[2] “New connection identifier approach”, 22-09-0112-05-0000, Jul. 2010.[3] “Overview of CBP”, 22-07-0136-00-0000, Apr. 2007.[4] “802.22 Coexistence Aspects ”, 22-10-0121-02-0000, Sep. 2010.[5] “Channel Management in IEEE 802.22 WRAN Systems”, IEEE Communication Mag

azine, vol.48, No.9, Sep. 2010.[6] “IEEE P802.22-2011: Standard for Wireless Regional Area Networks Part 22: Cognit

ive Wireless RAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Policies and procedures for operation in the TV Bands”, Jul. 2011.

[7] “IEEE 802.22 Wireless Regional Area Networks”, 22-10-0073-03-0000, Jun. 2010.

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