June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 Wireless Regional Area Networks
Enabling Rural Broadband Wireless Access Using Cognitive Radio Technology
IEEE P802.22 Wireless RANs
Date: 2010-06-15
Authors:
Name
Company
Apurva N. Mody BAE Systems
Gerald
Chouinard
Address
Phone
email
P. O. Box 868,
MER 15-2350,
Nashua, NH 03061
1-404-8190314, 1-603885-2621
apurva.mody@baesyst
ems.com,
apurva_mody@yahoo.
com
1-613-9982500
Gerald.chouinard@crc
.ca
Communication
s Research
Center, Canada
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
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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
Apurva N. Mody < apurva.mody@ieee.org > 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 patcom@iee.org.
>
Submission
Slide 1
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
Outline
•
IEEE 802.22 Standard Overview
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–
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–
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–
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IEEE Standards and IEEE 802.22
Overview of the IEEE 802.22
CONOPS
Reference Architecture
Frame Structure
PHY
MAC
Cognitive Radio Capabilities
Spectrum Sensing
Geo-location
Interface to Incumbent Database Service
Security
Submission
Slide 2
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE Standards Association Hierarchy
Courtesy, Paul Nikolich, Chair,
IEEE 802
802.22
WRAN
Submission
More than 300
Standards Being
Developed Under
the IEEE SA
Umbrella
802.11
WLAN
Slide 3
802.15
WPAN
June 2010
doc.: IEEE 802.22-10/0073r03
Overview of the IEEE 802.22 Standard
• Focus - Rural Broadband Wireless Access
• Core Technology - Cognitive radio technology based
un-licensed use, primarily designed to operate in the
TV Whitespaces from 54-862 MHz, on a noninterfering basis with the primary users (incumbents).
Cognitive radio based unlicensed usage, ideally
suited for regional and
rural broadband wireless
access
MAC provides
compensation for
long round trip
delays
• Representation – Commercial industry, Broadcasters,
Govt., regulators, and Academia
• Membership – 40 on an average
PHY optimized to
tolerate long channel
response and
frequency selective
fading channel
• Projects – IEEE 802.22, IEEE 802.22.1, IEEE
802.22.1
• CONOPS - VHF and UHF band operation allows long
range propagation and cell radius of 17 – 33 km.
Approx 280 MHz of Bandwidth with 47 TV channels.
• PHY - Optimized for long channel response times and
highly frequency selective fading channels.
• MAC – Provides compensation for long round trip
delays
• Unique features introduced for Cognitive Radio based
operation: spectrum sensing, spectrum management,
intra-system co-existence, geo-location and security
Submission
• Mobility and Portability - Portability – IEEE 802.22
allows portability (nomadic use). In case the rules do
change, IEEE 802.22 PHY is designed to support mobility
of up to 114 km/hr (no hand-off is included in the current
version).
Slide 4
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 CONOPS
Sensing and GPS
Antennas
Directional Tx / Rx
Antenna at the
Subscriber
• Operation in the VHF / UHF Bands. Frequency Allocation for the
United States – 54 – 60, 76 – 88, 174 – 216, 470 - 608 and 614 –
698 MHz => Total of 282 MHz or 47 Channels
• Network Topology – Point-to-Multipoint (PMP)
• Max EIRP and Cell Radius – Fixed BS and Fixed Subscribers
using 4W EIRP, Cell Radius 10 – 100 km. Portable Subscribers
Station Supported. (Higher power BS allowed in other countries)
• Tx / Rx antenna – BS uses sectorized or omni-directional antenna.
At the subscriber Tx /Rx antenna is directional with 14 dB of frontto-back lobe suppression,
• Sensing antenna - Requires horizontal and vertical polarization
sensitivities to sense TV and microphone signals respectively, with
omni-directional pattern.
• Geo-location - GPS based geo-location is mandatory, but terrestrial
geo-location (triangulation) is supported.
Submission
Slide 5
Apurva N. Mody, BAE Systems
doc.: IEEE 802.22-10/0073r03
June 2010
IEEE 802.22
Cognitive Node: Reference
Architecture
• The proposed Protocol
Reference Model (PRM)
separates the Cognitive Plane
from the Data, Control and
Management planes
IEEE 802.22 Provides Three
Mechanisms for Incumbent
Protection
• Sensing
• Database Access
• Specially Designed Beacon
One or more protection
mechanisms can be adopted
based on the regulatory domain
requirements.
Submission
Slide 6
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
• 802.22 supports Time Division
Duplex (TDD) frame structure
IEEE 802.22 – Frame Structure
• Super-frame: 160 ms, Frame: 10 ms
• Each frame consists of downlink
(DL) sub-frame, uplink (UL) subframe, and the Co-existence Beacon
Protocol (CBP) burst
• Lengths of DL and UL sub-frames
can be adjusted .
• Self Co-existence Window: BS
commands subscribers to send out
CBPs for 802.22
• self co-existence – CBP bursts
contain information about the backup
channel sets and sensing times
• terrestrial geo-location and
• whitespace device identification as
required by the regulatory domain
rules.
Co-existence Beacon Protocol (CBP) burst
used for 802.22 self co-existence and
terrestrial geo-location
Submission
Slide 7
A
CBP
B
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – PHY Features
• PHY Transport - 802.22 uses Orthogonal Frequency Division
Multiplexing (OFDM) as transport mechanism. Orthogonal Frequency
Division Multiple Access (OFDMA) is used in the UL
• Modulation - QPSK, 16-QAM and 64-QAM supported
• Coding – Convolutional Code is Mandatory. Turbo, LDPC or Shortened
Block Turbo Code are Optional but recommended.
• Pilot Pattern - Each OFDM / OFDMA symbol is divided into subchannels of 28 sub-carriers of which 4 are pilots. Pilot symbols are
inserted once every 7 sub-carriers. Pilots cycle through all 7 sub-carriers
over 7 symbol duration. No frequency domain interpolation is required.
• Net Spectral Efficiency - 0.624 bits/s/Hz – 3.12 bits/s/Hz
• Spectral Mask - 802.22 has adopted the Spectral Mask requirements
proposed by FCC. (200 tap FIR filter may be needed for implementation).
PHY capacity
Mod.
Rate
1/2
2/3
QPSK
3/4
5/6
1/2
2/3
16QAM
3/4
5/6
1/2
2/3
64QAM
3/4
5/6
Submission
Slide 8
Mbit/s bit/(s*Hz)
CP= 1/8
3.74
0.624
4.99
0.832
5.62
0.936
6.24
1.04
7.49
1.248
9.98
1.664
11.23
1.872
12.48
2.08
11.23
1.872
14.98
2.496
16.85
2.808
18.72
3.12
PHY performance: SNR (dB)
Mod.
Rate
SNR
1/2
4.3
2/3
6.1
QPSK
3/4
7.1
5/6
8.1
1/2
10.2
2/3
12.4
16QAM
3/4
13.5
5/6
14.8
1/2
15.6
2/3
18.3
64QAM
3/4
19.7
5/6
20.9
Note: includes phase noise: -80dBc/Hz at
1 kHz and 10 kHz and -105 dBc/Hz at
100 kHz
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – MAC Features
• Connection-oriented MAC, establishes connection IDs and service flows which are dynamically created
• QoS – Various types of QoS services are supported (See below). ARQ supported. Uni-cast, Multi-cast and broadcast
services are supported.
• Cognitive functionality –
• Dynamic and adaptive scheduling of quiet periods to allow the system to balance QoS requirements of users with
the need to quiet down the network to support spectrum sensing. Quiet periods range from 1 symbol (approx. 1/3
ms) to one super-frame
• Subscribers can alert the BS, the presence of incumbents in a number of ways. Dedicated - Urgent Co-existence
Situation (UCS) messages or low priority MAC messages
• BS can ask one or more subscribers to move to another channel in a number of ways using
160 ms
Frame Control Header (FCH)
or dedicated MAC messages
... Time
...
Superframe n-1
Superframe n
Superframe n+1
10 ms
frame 0
QoS
Application
UGS
VoIP, T1 / E1
rtPS
MPEG video
streaming
10 ms
10 ms
. . .
frame 1
frame 15
Quiet Period
Quiet Period
Intra-frame quiet period scheduling
160 ms
nrtPS
FTP
BE
E-mail
Contention
BW request etc.
...
Superframe n-1
Superframe n+1
...
Quiet Period
10 ms
10 ms
frame 0
10 ms
. . .
frame 1
frame 15
Quiet Period
Inter frame quiet period scheduling
Submission
Slide 9
Apurva N. Mody, BAE Systems
Time
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – Cognitive Radio Capability
Channel Set Management
Policies
Subscriber Registration
and Tracking
Spectrum Manager
Geo-location
Self Co-existence
Super-frame N+1 (16 Frames)
Super-frame N (16 Frames)
TV Channel
X Cell 1 Cell 2 Cell 3
…
Cell 3 Cell 1 Cell 2 Cell 1 Cell 1
…
Cell 2 Cell 3
…
time
Data Frames
Spectrum Sensing
Incumbent Database
Service
RF sensing performance
Probability of misdetection (Pmd)
100.0%
Incumbent
10.0%
Energy - 1dB Pfa=10% 5 ms
Energy - 0.5dB Pfa=10% 5 ms
Energy - 0dB Pfa=10% 5ms
1.0%
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
Database
Submission
Coexistence Beacon Windows
Qualcom Field Pfa=1% 24 ms
Thomson Field Pfa=10% 24 ms
Thomson Field Pfa=1% 24ms
0.1%
-26
Slide 10
-24
-22
-20
-18
-16
-14
SNR (dB)
-12
-10
-8
-6
-4
Apurva N. Mody, BAE Systems
-2
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – Spectrum Sensing
DTV Detection Results based Cyclostationary
Feature Detection
TV and Wireless Microphone Protection Using Spectrum
Sensing
• FCC R&O requires
• DTV protection at -114 dBm in 6 MHz of bandwidth. This amounts to
an SNR of -19 dB for equivalent receiver noise figure of 11 dB and 22
dB safety margin at edge of coverage
• Wireless microphone protection at -114 dBm in 200 kHz bandwidth.
This amounts to an SNR of -3 dB for equivalent. recceiver noise figure
of 11 dB.
• Several blind and signal specific feature-based sensing schemes have
been proposed and thoroughly evaluated using TV Broadcaster supplied
over-the-air collected signals
► Spectral correlation based sensing,
Time domain cyclostationarity,
Eigen value based sensing,
FFT – based pilot sensing,
Higher order statistics based sensing, etc.
Pd = >99%, Pfa =
10%, -20dB
Wireless Microphone Beacon Sensing Results
-95
Wireless Microphone Protection Using Beacon (IEEE
802.22.1 Standard – Nearly Complete)
-100
-105
Sensing threshold (dBm)
• Many studies have suggested that FCC R&O target for wireless
microphones is not sufficient to protect wearable microphones
(where body attenuation of as much as 27dB is possible according to
the manufacturers)
• 802.22 has designed a beacon signal which will be transmitted from
wireless microphone base stations with 250 mW (as compared to 10
mW for microphones). These beacon signals consist of repeated
pseudo-noise (PN) sequences and occupy a bandwidth of 78 kHz.
• Security features are provided for beacon authentication
1-
En
e
rgy
de
tec
ti
on
TG1
certificate
-110
-114 dBm
TG1
signature
TG1 information
(FEC encoded)
-115
8-chip spreading
sequence
-120
1-E
nerg
y
dete
-125
ctio
n co
rrela
Sync and index
ted
on s
prea
d
sequ
ence
-130
0.1
1
10
Minimum sensing time (ms)
Submission
Slide 11
Apurva N. Mody, BAE Systems
100
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – Geo-location
X
...
Satellite-based geo-location
Frequency
• Requires GPS antenna at each terminal
• NMEA 0183 data string used to report to BS
• Poor accuracy in Northern hemispheres.
Signal Processing Flow for the Terrestrial
Geo-location
OFDM carrier set
2048 carriers BPSK
modulated by PN-sequence
I
PN-sequence
Q
I
IDFT
I
Q
Carrier phase reversal
based on the PN-sequence
Q
I
Terrestrially-based geo-location:
Time
...
I
2048 time domain samples
Slide 12
Q
Frequency
Frequency domain response of a
Dirac pulse distorted by channel
2048 carriers
I
Q
Time
Cyclic prefix
Signal transmitted
to terminal 2
I
IDFT
Q
I
I
Real
Convolution with the
channel impulse response
Q
Q
Channel impulse response
relative to the sampling time
2048 I&Q samples at sampling
period (i.e., every 180 degrees)
times
Sampling
Ima
gina
ry
I
Q
1
Time
τ
1
2048 samples
Signal received
by the user terminal
I
Real
• A new scheme has been proposed requiring no additional
hardware and using the characteristics and capabilities of
the 802.22 standard.
• Normal BS-CPE ranging process: provides coarse ranging
to an accuracy of 147.8 ns (44.3 m)
• Extended BS-CPE ranging process: augments the accuracy
of the ranging process to 1 ns (0.3 m) by a more accurate
scheme using the complex channel impulse response
received at the CPE (Vernier-1) and at the BS (Vernier-2)
• Extended CPE-CPE ranging process: new scheme using
the preamble of the CBP burst transmitted by a CPE and
captured by another CPE in the surrounding area to acquire
the distance between CPEs with a high level of accuracy
(Vernier-3)
• Off-line geo-location calculation: All the information
acquired at the CPEs is transmitted to the BS which can
delegate the calculation of the CPE geo-location to a
server. Calculation is based on usual triangulation using
some CPEs as waypoints.
Submission
Y/X
Q
0
Q
I
Q
0
Im
aginary
DFT
I
Y
Frequency
I
Precise tim
e sam
ple
I
Q
OFDM carrier set
distorted by channel
2048 carriers
1
High resolution band
limited impulse response
(e.g., every 1 degree)
...
Complex
correlation
-1
1
Q
2048 x 180 I&Q samples
at every degree
Q
τ
2
τ
τ
3
1
Channel impulse response
relative to the sampling time
Amplitude1
Amplitude2
Amplitude3
Amplitude4
etc...
Delay 1
Delay 2
Delay 3
Delay 4
List of echo amplitudes and delays
relative to the terminal 2 sampling time
Resolution= sampling period / 180
Signal sent back to terminal 1
Apurva N. Mody, BAE Systems
12
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – Self Co-existence
Requires that information on
Spectrum Etiquette
On Demand Frame
operating, backup and candidate
(Enough channels available)
channels of each cell is shared
Contention
amongst WRAN cells:
(Two or more cells need to co-exist on
the same channel)
exchanged by CBP bursts.
Primary user
appears
Number x – represents operating channel
Number y – represents backup channel
Number z (double underline) – represents candidate channel
Self-coexistence window
(SCW) does not have to
be allocated at each
frame.
Super-frame N+1 (16 Frames)
Super-frame N (16 Frames)
TV Channel
Cell 1
X
Cell 2
Cell 3
…
Cell 3
Cell 1
Cell 2
Cell 1
Cell 1
…
Cell 2
Cell 3
…
time
Data Frames
Submission
Coexistence Beacon Windows
Slide 13
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – Security Sub-layer 1 (Non-Cognitive)
• Confidentiality and Privacy – AES (128) GCM is
used for encryption and authentication
• Network Authorization - RSA and ECC based X.509
certificates are used for mutual authentication /
network entry authorization.
• Integrity – AES-GCM is used to compute Integrity
Check Vector (ICV). PN sequence numbers are
appended to each packet.
• Authentication – Signals such as wireless
microphone beacon and CBP are authenticated using
ECC based digital signatures. No encryption is
provided for these packets
• Key Management - Secure Control and Management
Protocol is used for key management.
• Management Messages – All management messages
except for the broadcast, initial ranging and basic
CID are protected.
• Device Security - Trusted Computing Group,
Trusted Platform Module specifications are
recommended to enable tamper-proof capability for
hardware and software.
Submission
Security Sub-layer 1
Slide 14
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
IEEE 802.22 – Security Sub-layer 2 (Cognitive)
• Spectrum Availability • Spectrum Sensing used to ensure spectrum
availability for primary users.
• Various types of signal specific and feature based
sensing algorithms have been included into the
standard
• Standard recommends sensing algorithms to
determine the signal type (Signal Classification)
• Collaborative Sensing - The group in general thinks
that collaborative sensing will be useful. FCC R&O
requires ‘OR’ rule based collaborative sensing.
• Correlation with Geo-location Information –
Closely tied to collaborative sensing. It tries to
cross check the spectral footprint of the detected
signal based on location of the sensor
Security Sub-layer 2
• Spectrum Access Authorization –
• BS is capable of de-authorizing a subscriber at any
time. Sensing and incumbent database service used
for spectrum access authorization
• Capability Check – The Spectrum Manager (SM) is
capable of prohibiting a subscriber from registering
if it does not have adequate sensing capabilities.
Signal
classification
and policy
based
behavior
control of the
802.22 devices
• Radio Behavior Control
• IEEE 802.22 is policy driven. Policies are rulebased.
Submission
Slide 15
Apurva N. Mody, BAE Systems
June 2010
doc.: IEEE 802.22-10/0073r03
References
• IEEE 802.22 Working Group Website – www.ieee802.org/22
• J. Mitola, Cognitive Radio: An Integrated Agent Architecture for Software Defined
Radio, Ph. D. Thesis, Royal Institute of Technology, Sweden, Spring 2000.
• Gerald Chouinard, Communications Research Center, 802.22 Overview presentation to
the 802 Whitespaces Study Group https://mentor.ieee.org/802-sg-whitespace/dcn/09/sgwhitespace-09-0058-00-0000-802-22-presentation-to-ecsg.ppt
• IEEE 802.22 Draftv3.0 – Members only Documents of the IEEE 802.22 Working Group
(www.ieee802.org/22)
• Other Contributions to the IEEE 802.22 Standard (www.ieee802.org/22)
Submission
Slide 16
Apurva N. Mody, BAE Systems