January 2006
doc.: IEEE 802.22-06/0009r0
A PHY/MAC Proposal for IEEE 802.22
WRAN Systems
IEEE P802.22 Wireless RANs
Date: 2006-01-09
Authors:
Name
Company
Address
Phone
Email
Martial Bellec
France Telecom
France
+33-2-99-124806
Martial.bellec@francetelecom.com
Yoon Chae Cheong
SAIT
Korea
+82-31-280-9501
Yc.cheong@samsung.com
Carlos Cordeiro
Philips
USA
+1-914-945-6091
Carlos.Cordeiro@philips.com
Chang-Joo Kim
ETRI
Korea
+82-42-860-1230
cjkim@etri.re.kr
Hak-Sun Kim
Samsung Electro-mechanics
Korea
+82-31-210-3500
hszic.kim@samsung.com
Joy Laskar
Georgia Institute of Technology
USA
+1-404-894-5268
joy.laskar@ece.gatech.edu
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 patcom@iee.org.
>
Submission
Slide 1
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Co-Authors
Name
Company
Address
Phone
email
Myung-Sun Song
ETRI
Korea
+82-42-860-5046
mssong@etri.re.kr
Soon-Ik Jeon
ETRI
Korea
+82-42-860-5947
sijeon@etri.re.kr
Gwang-Zeen Ko
ETRI
Korea
+82-42-860-4862
gogogo@etri.re.kr
Sung-Hyun Hwang
ETRI
Korea
+82-42-860-1133
shwang@etri.re.kr
Soon-Soo Oh
ETRI
Korea
+82-42-860-4974
ssoh@etri.re.kr
Bub-Joo Kang
ETRI
Korea
+82-42-860-5446
kbj64370@etri.re.kr
Chung Gu Kang
ETRI
Korea
+82-2-3290-3236
ccgkang@korea.ac.kr
KyungHi Chang
ETRI
Korea
+82-32-860-8422
khchang@inha.ac.kr
Yoan Shin
ETRI
Korea
+82-2-820-0632
yashin@e.ssu.ac.kr
Yun Hee Kim
ETRI
Korea
+82-31-201-3793
yheekim@khu.ac.kr
Kyesan Lee
ETRI
Korea
+82-31-201-2032
kyesan@khu.ac.kr
Moon Ho Lee
ETRI
Korea
+82-63-270-2463
moonho@chonbuk.ac.kr
Denis Callonnec
France Telecom
France
+33-4-76-764412
Denis.Callonnec@francetelecom.com
Luis Escobar
France Telecom
France
+33-2-45-294622
Luis.Escobar@francetelecom.com
Francois Marx
France Telecom
France
+33-4-76-764109
Francois.Marx@francetelecom.com
Patrick Pirat
France Telecom
France
+33-2-99-124806
Ppirat.ext@francetelecom.com
Submission
Slide 2
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Co-Authors
Name
Company
Address
Phone
email
Kyutae Lim
Georgia Institute of
Technology
USA
+1-404-385-6008
ktlim @ece.gatech.edu
Youngsik Hur
Georgia Institute of
Technology
USA
+1-404-385-6008
yshur @ece.gatech.edu
Dagnachew Birru
Philips
USA
+1-914-945-6401
Dagnachew.Birru@philips.com
Kiran Challapali
Philips
USA
+1-914-945-6357
Kiran.Challapali@philips.com
Vasanth Gaddam
Philips
USA
+1-914-945-6424
Vasanth.Gaddam@philips.com
Monisha Ghosh
Philips
USA
+1-914-945-6415
Monisha.Ghosh@philips.com
Gene Turkenich
Philips
USA
+1-914-945-6370
Gene.Turkenich@philips.com
Duckdong Hwang
SAIT
Korea
+82 31 280 9513
duckdong.hwang@samsung.com
Ashish Pandharipande
SAIT
Korea
+82 010-6335-7784
pashish@ieee.org
Jeong Suk Lee
Samsung ElectroMechanics
Korea
+82-31-210-3217
js0305.lee@samsung.com
Chang Ho Lee
Samsung ElectroMechanics
Korea
+82-31-210-3217
changholee@samsung.com
Wangmyong Woo
Samsung ElectroMechanics
Korea
+82-31-210-3217
wmwoo@samsung.com
Submission
Slide 3
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Co-Authors
Name
David Mazzarese
Baowei Ji
Submission
Company
Samsung
Electronics Co.
Ltd.
Samsung Telecom
America
Address
Phone
Korea
+82 10 3279 5210
USA
+1-972-761-7167
Slide 4
email
d.mazzarese@samsung.com
Baowei.ji@samsung.com
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Presentation Outline
• Introduction
– A Glimpse of IEEE 802.22
• The PHY Proposal
• The MAC Proposal
• Conclusions
Submission
Slide 5
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Presentation Outline
• Introduction
– A Glimpse of IEEE 802.22
• The PHY Proposal
• The MAC Proposal
• Conclusions
Submission
Slide 6
Martial Belec, France Telecom
January 2006
Submission
doc.: IEEE 802.22-06/0009r0
Slide 7
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
The IEEE 802.22
• From 18 Mbps to 24 Mbps
RAN
< 100 km
802.22 (proposed) - 18 to 24 Mbps
WAN
• Propagation delays in excess
of 300 µs
< 15 km
802.20 (proposed)
GSM, GPRS, CDMA, 2.5G, 3G – 10
kbps to 2.4 Mbps
MAN
< 5 km
• Operates in TV bands
802.16a/d/e - 70 Mbps
LMDS - 38 Mbps
– 54 to 862 MHz
– 6 MHz, 7 MHz and 8 MHz
channel bandwidth
LAN
< 150 m
11 – 54 Mbps
802.11a/b/e/g
HiperLAN/2
802.11n (proposed) > 100 Mbps
PAN
< 10 m
802.15.1 (Bluetooth) – 1 Mbps
802.15.3 > 20 Mbps
802.15.3a (UWB) < 480 Mbps
802.15.4 (Zigbee) < 250 kbps
Submission
Slide 8
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Deployment Scenario
CPE
• Master/Slave relationship
CPE
BS
• Entities
CPE
CPE
33 - 100 Km
– Base Station (BS)
– Consumer Premise Equipment
(CPE)
CPE
CPE
BS
CPE
CPE
BS
CPE
• 4W CPE transmit power
BS
CPE
CPE
CPE
Backbone Network
Submission
Slide 9
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Presentation Outline
• Introduction
– A Glimpse of IEEE 802.22
• The PHY Proposal
• The MAC Proposal
• Conclusions
Submission
Slide 10
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
WRAN Hierarchy
Public IP Network
SD
Service Provider IP Network
HA
AAA
ACR
ACR
집
CPE
WRAN
BS
집
집
집
• AAA : Authentication, Authorization and Account Server
• ACR : Access Control Router HA : Home Agent
Submission
Slide 11
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Deployment Scenario
집
집
집
WRAN
Base Station
집
집
집
집
집
Wireless
MIC
집
집
집
집
집
집
집
집
집
집
TV Transmitter
WRAN
Base Station
집
집
집
집
집
집
WRAN
Repeater
집
집
Wireless
MIC
: WRAN Base Station
Typical ~33km
Max. 100km
집
집
집
집
집
집
집
집
집
집
집
집
집
집
집
: CPE
집
집
집
Submission
Slide 12
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
PHY Overview
•
•
•
•
OFDMA both in uplink and downlink
QPSK, 16-QAM, and 64-QAM, spreaded-QPSK
More than 32 sub channels
Contiguous channel bonding upto 3 TV channels ( and beyond in a
stack manner)
• Data rate range from 5Mbps to 60Mbps
• TDD, FDD
Randomizer
Submission
FEC
Interleaver
Slide 13
Modulation
(constellation
mapping)
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
What We Have Proposed ….
Adaptive
OFDMA
Known and proven technology
for broadband fixed/mobile wireless access
(e.g., IEEE 802.16d/e – WiBro in Korea)
• Adaptively scalable to spectrum availability
• New frame structure for CR-enabled operation
• Enhanced PHY features
- Adaptive sub-carrier allocation
- Adaptive pilot insertion
- Enhanced channel coding, e.g., LDPC
Submission
Slide 14
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
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, i.e., 64/7MHz, for all FFT modes.
• Constant Subcarrier Spacing
– The subcarrier spacing is constant for all different channel
bandwidths  Robust to the frequency offset
Submission
Slide 15
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
System Parameters: Proposed
Parameters
Specification
Frequency range
54~862 MHz
Service coverage
Typical range 33 km,
Bandwidth
• Mandatory: 6, 7, 8 MHz with channel bonding
• Optional: fraction BW
Data rate
Spectral Efficiency
• Maximum: 93 Mbps
• Minimum: 4.46 Mbps
• Maximum: 5.20 bits/s/Hz
• Minimum: 0.74 bits/s/Hz
Modulation
QPSK, 16QAM, 64QAM
Transmit power
Multiple Access
FFT Mode
Cyclic Prefix Mode
Duplex
Network topology
Default 4W EIRP
Adaptive OFDMA
1024, 2048, 4096, 6144
1/4, 1/8, 1/16, 1/32
TDD or FDD
Point-to-Multipoint Network
Submission
Remark
Allows the fractional use of TV
channel and channel bonding up
to 3 TV channel
Maximum of 31Mbps for 6MHz
Apply to all bandwidth
Partial bandwidth allocation
Slide 16
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Bonding
• More data rate
• 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
Submission
Slide 17
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
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
Submission
Slide 18
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel bonding
• 6, 12, 18 MHz channels
• Constant inter-carrier
spacing
TV
TV
WRAN
N-3
• Depends on availability
N-2
N-1
N
N+1
N+2
N+3
N+4
TV
• Several receiver techniques to
deal with flexible BW
TV
WRAN
N-3
N-2
N-1
N
N+1
N+2
N+3
N+4
– Selectable analog filters
– Up sampling digital filters
TV
TV
WAN
N-3
Submission
Slide 20
N-2
N-1
N
N+1
N+2
N+3
N+4
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel bonding structure
• 6K FFT over 3 TV channels
• Fixed inter-carrier spacing
– 2K per TV channel
– Null out the outer carriers for 1
or 2 TV channels
– Several implementation
possibilities
DC
Data
Sub-carrier
6 6MHz
MHz
Pilot
Sub-carrier
DC
1212 MHz
MHz
Guard/Null
Sub-carrier
DC
1818MHz
MHz
Submission
Slide 21
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
PHY (Baseband) Architecture
P/S
Guard
Insertion
S/P
Guard
Removal
IFFT
Preamble
&
Pilot
Insertion
Subcarrier
Allocator
S/P
FFT
Channel
Estimation
Subcarrier
Deallocator
P/S
Mapper
Puncturer
&
Interleaver
Encoder
Randomizer
Demapper
Deinterleaver
&
Depuncturer
Decoder
Derandomizer
Binary
Data
Channel
AWGN
Recovered
Data
Synchronization
Submission
Slide 23
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Spectrum of the signal (before further
filtering)
Produced using a
6K FFT
for a single TV
channel
Submission
Slide 24
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
802.22 proposed relative RF emission
Proposed Relative RF Emission Mask
(Output filter requirement)
Required Out-of-band Rejection (dB)
0
-10
Mask w ith TPC cap
Part 15.209a at min. dist.
-20
Proposed Base RF Mask
Equivalent 1stAdj. Ch.
-30
-40
-50
-60
-70
-80
-90
-100
-20
-15
-10
-5
0
5
10
15
20
Channel Spacing
Submission
Slide 25
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
OFDMA parameters-channel bonding
Parameter
Inter-carrier spacing,
F (Hz)
FFT period, TFFT (s)
Total no. of subcarriers,
NFFT
No. of guard subcarriers,
NG (L, DC, R)
No. of used subcarriers,
NT = ND+ NP
No. of data subcarriers,
ND
No. of pilot subcarriers, NP
Signal bandwidth
(MHz)
Submission
3 TV bands
18
21
24
2 TV bands
12
14
16
6
1 TV band
7
8
3348
3906
4464
3348
3906
4464
3348
3906
4464
298.66
256.00
224.00
298.66
256.00
224.00
298.66
256.00
224.00
6144
4096
2048
960 (480, 1, 479)
640 (320, 1, 319)
320 (160, 1, 159)
5184
3456
1728
4608
3072
1536
576
384
192
17.356
20.249
23.141
Slide 26
11.571
13.500
15.428
5.785
6.750
7.714
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
OFDMA Parameters/single channel
Mode
1K
2K
4K
8K ???
FFT Size
1024
2048
4096
8192
Bandwidth
(k = 1, 2, …, 8)
k MHz
k MHz
k MHz
k MHz
Sampling Factor
8/7
8/7
8/7
8/7
No. of Used Subcarriers
(including pilot, but not DC)
104 * k
209.5 * k
416 * k
832 * k
Sampling Frequency
64/7 MHz
64/7 MHz
64/7 MHz
64/7 MHz
Subcarrier Spacing
8.928 kHz(***)
4.464 kHz
2.232 kHz
1.116 kHz
Occupied Bandwidth
8.928 kHz*104*k
4.464 kHz*208*k
2.232 kHz*416*k
1.116 kHz*832*k
Bandwidth Efficiency(*)
92.97~93.75 %
92.91~93.30 %
92.89~93.08 %
92.87~92.97 %
FFT Time
112 us
224 us
448 us
896 us
Cyclic Prefix Time(**)
28 us
56 us
112 us
224 us
OFDMA Symbol Time
140 us
280 us
560 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.
Submission
Slide 27
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
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
Example structure
ST1
Submission
ST2
ST3
TSYM
ST4
ST5
GI
(short)
LT1
LT2
(long)
Slide 28
TMartial
SYM Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Preamble
• Preamble has the repetition pattern in the time domain:
– Time synchronization
– Frequency synchronization
– Channel estimation
– Cell ID detection
• Preamble is modulated using a boosted BPSK modulation
Submission
Slide 29
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Spreaded QPSK/OFDMA
• Spread data over some subcarriers (QPSK only)
– Hadamard
– Two-carrier
– FFT based unitary pre-coding
•
Depending on the receiver
structure, this can
Time (in OFDM symbol unit)
– increase capturing of multipath
1
diversity
subchannels 2
3
– Increase resiliency
4
to interferers
•
dev3
Dev2 (16QAM)
Dev4 (S-QPSK)
Dev8
(64QAM)
dev5 (16QAM)
Receiver structure
Dev7 (S-QPSK)
– MMSE
– Approximate ML
Submission
dev 1
(64QAM)
dev6 (64QAM)
Slide 30
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Preliminary Link Budget(LOS)
modulation
coding rate
Throughput/channel
center frequency
bandwidth
Distance
Tx power
Tx averg power
TX antenna gain
Rx power
free space path loss
Rx antenna gain
cable and other losses
Total received avrg power
Receiver noise figure
Noise power
Interference allowance
Received SNR
Required SNR
Implementation/OFDM loss
Link Margin
Submission
QPSK
64-QAM
1/2
5
0.7
6
30000
4
36.0
0.0
2/3
19
0.7
6
6000
4
36.0
0.0
16-QAM
1/2
29
0.7
18
30000
4
36.0
0.0
Mb/s
GHz
MHz
m
W
dBm
dBi
119
12
3
-74
4
-106
3
25
4
6.0
15.4
105
12
3
-60
4
-106
3
39
25
6.0
8.3
119
12
3
-74
4
-101
3
21
10
6.0
4.6
dB
dBi
dB
dBm
dB
dBm
dB
dB
dB
dB
dB
Slide 31
Difficult to
achieve
19Mbps over
30Km without
channel
bonding
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Superframe Structure
...
Superframe n-1
Preamble
SCH
Superframe n
frame 0
...
Superframe n+1
...
frame 1
Time
frame m
Occupied by Incumbent
Frequency
Occupied by Incumbent
TV Channel
Preamble SCH
t-1
TV Channel
Preamble SCH
t
Frame
0
Frame
1
...
Frame
m-2
(Quiet)
Frame
m-1
TV Channel
Preamble SCH
t+1
Preamble SCH
Frame
m
... Frame
0
Frame
1
Frame
n
Preamble SCH
Occupied by Incumbent
Submission
Slide 32
Time
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Data Rate
•
•
•
•
Bandwidth = 6MHz
Quiet periods are NOT accounted
FFT size = 2048
Cyclic prefix mode = 1/4
Unit: Mbps
Code Rate
7/8
5/6
3/4
2/3
1/2
64QAM
23.40
22.29
20.06
17.83
13.37
16QAM
15.60
14.86
13.37
11.87
8.91
QPSK
7.80
7.43
6.69
5.94
4.46
Modulation
Data Rate = No. of data subcarriers(???) * code rate * no. of bits per modulation symbol/OFDM symbol
time
Submission
Slide 33
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Data Rate-channel bonding
•
•
•
•
Bandwidth = 3*6MHz
Quiet periods and preambles are NOT accounted
FFT size = 2048
Cyclic prefix mode = 1/4
Unit: Mbps
Code Rate
7/8
5/6
3/4
2/3
1/2
64QAM
23.40
22.29
20.06
17.83
13.37
16QAM
15.60
14.86
13.37
11.87
8.91
QPSK
7.80
7.43
6.69
5.94
4.46
Modulation
Data Rate = No. of data subcarriers(???) * code rate * no. of bits per modulation symbol/OFDM symbol
time
Submission
Slide 34
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Spectral Efficiency
• Quiet periods and preambles are NOT accounted
• FFT size = 2048
• Cyclic prefix mode = 1/4
Unit : bps/Hz
Code Rate
7/8
5/6
3/4
2/3
1/2
64QAM
3.90
3.71
3.34
2.97
2.23
16QAM
2.60
2.48
2.23
1.98
1.49
QPSK
1.30
1.24
1.11
0.99
0.74
Modulation
Spectral Efficiency = No. of data subcarrier*code rate*no. of bits per modulation symbol/OFDM symbol time/BW
The proposal meets the spectral efficiency in the FRD:
min 0.5 bps/Hz, max 5 bps/Hz or better
Submission
Slide 35
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Minimum Peak Throughput per CPE
•
•
•
•
•
Bandwidth = 6MHz
Quiet periods and preambles are NOT accounted
FFT size = 2048
Cyclic prefix mode = 1/4
No. of CPE’s = 512 CPE’s/oversubscription ratio 50 ~ 11 CPE’s
Unit : Mbps
Code Rate
Modulation
64QAM
16QAM
QPSK
7/8
5/6
3/4
2/3
1/2
2.13
1.42
0.71
2.03
1.35
0.68
1.82
1.22
0.61
1.62
1.08
0.54
1.22
0.81
0.41
Min. Peak Throughput = No. of used subcarriers*code rate*no. of bits per modulation symbol/OFDM symbol time/no. of CPE’s
 The proposal meets the minimum peak throughput in the FRD:
1.5 Mbps (DL) and 384 kbps (UL)
Submission
Slide 36
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Subchannelization
Subcarrier Allocation
Distributed
Subcarrier permutation
Adjacent
Subcarrier Permutation
Scattered type
Band type
BIN
Band #1
Band #1
BIN
Band #2
Band #3
Band #2
Band #4
…
Band #3
Band #5
…
User 0
User 1
…
…
User 0
User 2
User 1
Band #24
User 2
User 3
Band #48
Symbol
Symbol
Submission
Slide 37
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Subchannelization (cont.)
• Type of subchannelization is determined by channel quality information
Adjacent
Subcarrier Permutation
Distributed
Subcarrier permutation
• Each subchannel consists of a
group of adjacent subcarriers
• Bands in good state are selected
for data transmission
• Multiuser diversity
• Require more feedback
information than distributed
subcarrier allocation type
Submission
• Each subchannel consists of
distributed subcarriers within an
OFDM symbol
• Only the average CINR over all
subcarriers is required
• For users with high frequency
selectivity or far distant users
Slide 38
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Subchannelization (cont.)
• Band-Type Adjacent Subcarrier Allocation
– To achieve the multi-user diversity gain
– Multiple bins allocated to each user
(Bin denotes a group of adjacent subcarriers).
BIN
Band #1
Band #2
Band #3
…
…
User 0
User 1
Band #24
User 2
Symbol
Submission
Slide 39
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Subchannelization (cont.)
• Scattered-Type Adjacent Subcarrier Allocation
– To achieve the multi-user diversity gain
– Only one bin allocated to each user
Band #1
BIN
Band #2
Band #3
Band #4
Band #5
…
User 0
…
User 1
User 2
User 3
Band #48
Symbol
Submission
Slide 40
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Subchannelization (cont.)
• Distributed Subcarrier Allocation
– Subcarriers are pseudo-randomly selected for frequency diversity
Number of used subcarriers
Subcarriers
Pilot subcarriers
...
Data subcarriers
...
Groups
G0
G1
G2
...
GN
...
Subchannels
Submission
Slide 41
S0
S1
SM
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Pilot Pattern
• Pilot pattern is varied with channel condition:
- Adaptively rotated pilot pattern
- Channel estimation by preamble or pilot, depending on power boosting
• Pilot subcarriers are modulated using a boosted BPSK
modulation
Preamble
OFDMA Symbol Direction
Data
Subcarrier
Subcarrier Direction
Direction
Pilot
Subcarrier
Period(variable)
Pilot
Subcarrier
Period(variable)
Pilot Symbol
Period(variable)
Pilot Symbol
Period(variable)
Pilot Symbol
Period(variable)
Boosted Pilot
Submission
Slide 42
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Coding
• Coding Scheme
–
–
–
–
LDPC Code
Convolutional Turbo Code
Convolutional Code
Concatenated Code : BCH+LDPC (CC or CTC)
• Code Rates
– For LDPC, R = 1/2, 2/3, 3/4, 5/6, 7/8 can be supported
– For CTC, R = 1/3, 1/2, 2/3, 3/4, 5/6, 7/8 can be supported
– For CC, R = 1/2, 2/3, 3/4, 5/6, 7/8 can be supported
Submission
Slide 43
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Coding (cont.)
• LDPC Encoder
• CTC Encoder
– Duo-binary CTC
output
A
A
B
B
1
CTC
Interleaver
Constituent
Encoder
2
C1
Y1W1
C2
Y2W2
ST
p1
Information bits
ST
ET-1
A
 1
T-1
B
p2
switch
Systematic part
C
H matrix
A
S1
S2
S3
n  m
m  p
A
B
T  I
D
E
p
B
p
p
Parity part
Y
W
C
Submission
Slide 44
m  p
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Coding (cont.)
• CTC Decoder
Le2 (u )
2

2
2
yk

2
S/P 
2
yp
2 1
MAP
INT
decoder L (u )
e1
ys
MAP
decoder
INT
2

2
DEINT
û k
y 2p
• LDPC Decoder
memQ
_even
B
B
memR
_even
A
memQ
_odd
B
B
memR
_odd
A: Bit_to_Check block ; memQ(even,odd):implement a pair of message buffers alternating between R/W
B: Check_to_Bit block ; memR(even,odd): implement a pair of message buffers alternating between R/W
Submission
Slide 45
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Coding (cont.)
• Performance Comparison: CTC vs. LDPC
- Code rate of 1/2 over WRAN channel model C
0
10
16QAM
QPSK
64QAM
256QAM
-2
10
Blue1
-4
10
BER
Blue2
-6
10
WRAN
Channel
profile C
Multi-path
Fading
-8
6-Paths
Carrier=617MHz
Dopper=0.10
200 Frames
-10
Blue1:
Blue2:
Red1:
Red2:
10
10
Submission
0
Red1
Red2
1/2Turbo message 728 bits
1/2Turbo message 1456 bits
1/2LDPC H size 728*1456
1/2LDPC H size 1456*2912
5
10
15
Eb/No(dB)
Slide 46
20
25
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Coding (cont.)
• Performance Comparison: CTC vs. LDPC
- Code rate of 2/3 over WRAN channel model C
0
10
QPSK
16QAM
64QAM
256QAM
-1
10
-2
10
Blue1
-3
BER
10
-4
10
-5
10
-6
10
-7
10
Submission
Blue2
Multi-path fading
6-Paths
WRAN Channel profile C
Carrier=617MHz
Dopper=0.10
200 Frames
Red1
Red2
Blue1:2/3Turbo message bits 728
Blue2:2/3Turbo message bits 1456
Red1:2/3 LDPC H size 364*1092
Red2:2/3 LDPC H size 728*2184
5
10
15
Eb/No(dB)
Slide 47
20
25
30
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Duo-binary Turbo-codes Outline
•
Duo-Binary Turbo Codes
•
Internal interleaver
•
Flexibility
•
Performance
•
Simulations
Submission
Slide 48
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Duo-Binary Turbo-codes
Information bits are encoded
by couples
Submission
Slide 49
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Duo-Binary Turbo-code
• Duo-Binary input: two decoded bit output at a time
– Reduction of latency and complexity per decoded bit (compared to
Binary TC)
– Better convergence
• Circular (tail-biting) encoding
– No trellis termination overhead
• Original interleaving scheme
– Larger minimum distances
– Improved asymptotic performances
Submission
Slide 50
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Internal Interleaver
•
Algorithmic permutation
–One equation, 4 parameters (P0, P1, P2,
P3)
–Parameters selected such that interleaver
is contention-free
i = 0, …, N-1, j = 0, ...N-1
level 1: if j mod. 2 = 0, let (A,B) = (B,A) (invert the
couple)
level 2:
•
Adjusting the TC to a blocksize only
requires modification of the 4
parameters
-
if j mod. 4 = 0, then P = 0;
-
if j mod. 4 = 1, then P = N/2 + P1;
-
if j mod. 4 = 2, then P = P2;
-
if j mod. 4 = 3, then P = N/2 + P3.
i = P0*j + P +1 mod. N
•
Quasi-regular permutation (easy
connectivity)
•
Inherent parallelism
Submission
Slide 51
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Flexibility
•
Can be easily adjusted to any blocksize
–Storage of the 4 parameters for all blocksizes considered
–Possibility of a generic approach (default parameters)
•
All coding rates are possible
–Through puncturing patterns
–Natural coding rate is ½: increased robustness to puncturing
•
Performance vs complexity: several adjustments are
possible
–Number of iterations, Decoding algorithm, …
•
Implementation: interleaver enables different degrees of
parallelism
–Can be adjusted to meet complexity/throughput requirements
Submission
Slide 52
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Flexibility
•
Submission
Slide 53
The number of
iterations can be
adjusted for a better
performancecomplexity trade-off
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Performance
Submission
Slide 54
•
Duo-Binary TC, 8
iterations, Max-LogMAP decoding
•
IEEE 802.16e
structured LDPC, BP
decoding, 50 iterations
•
AWGN, R=1/2, QPSK
•
N=576 and 2304 (coded
blocksize)
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Short blocksize performance
Submission
Slide 55
•
Hardware
measurements
•
Low BER
(down to 10-11)
are achievable
without error
floor
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Simulation results
• Simulation parameters
–
–
–
–
–
Constellation : 64 QAM
Coding rate : ½
Bandwidth : 7 MHZ
Channel: 641 MHz
Channel model: Profile A of WRAN
Profile A
0
Relative attenuation (dB)
-5
-10
-15
-20
-25
-30
-10
-5
0
5
10
15
20
25
30
35
40
45
50
55
60
Excess delay (usec)
Submission
Slide 56
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Duo-binary Turbo-codes vs Convolutional
with OFDM/QAM modulation
OFDM 64 QAM rate 1/2
13
14
15
16
17
18
19
20
21
0
-1
BER (log)
-2
Convolutional
-3
DTC
-4
-5
-6
C/N
Submission
Slide 57
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Advantages of Duo-binary Turbo-codes
• Good performance for a very wide range of blocksizes
• Highly flexible scheme, enabling a very fine granularity
– Same encoder/decoder for all blocksizes/coding rates.
– Several trade-off in performance (number of iterations, decoding
algorithm), implementation complexity (degrees of parallelism).
• Reasonable complexity
– Approximately 35% decrease in complexity per decoded bit
compared to Binary TC.
Submission
Slide 58
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
State of the art
• Duo-binary Turbo-code is a mature technology
• This technology has already been selected by several
standardization groups
–
–
–
–
Submission
IEEE 802.16 / WiMAX;
DVB-RCS;
DVB-RCT;
ETSI HIPERMAN
Slide 59
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Summary:
Gains brought by DTC
• Duo-binary TC offers 3,5 to 4 dB
• When combined the gain is at least 4,5 dB that allows
to increase the radius by 7,6 km (17%) with QPSK
modulation in a Gaussian channel.
Submission
Slide 60
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Transmit Diversity
•
•
•
•
•
Multiple antennae needed only at the base station.
CPE has only one transmit/receive chain.
Downlink uses transmit diversity methods.
Uplink uses receive diversity for combining.
Rate/ range increase for all CPEs with additional
complexity only at the base-station.
• Especially useful where channel-bonding cannot be
used for increased capacity.
Submission
Slide 61
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Multiple Antenna Techniques for 802.22
Systems: STBC
• Why STBC schemes for 802.22 systems?
–
–
–
–
Easily increase spectral efficiency by utilizing transmit diversity gain
Simple detection algorithm unlike the SM Techniques
No limit on the number of Rx antennas ==> high flexibility
No increase in hardware complexity: the same antennas for receive
diversity at BS can be used
– Significantly increase cell radius
• STBC Schemes
– Orthogonal code algorithms: Alamouti’s scheme (2Tx), Tarokh’s scheme
(3, 4Tx)
– Quasi-orthogonal code algorithm (4Tx), etc.
– Considering the spectrum band for 802.22 systems, the Alamouti scheme
employing two TX antennas seems most attractive.
Submission
Slide 62
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Multiple Antenna Techniques for 802.22
Systems: Adaptive BF
• Why adaptive beam-forming for 802.22 systems?
– Adaptive beam-forming can mitigate the effect of co-channel interference
(CCI) inherent to OFDMA systems, thereby increasing frequency reuse
factor close to unity.
– Since all CPE’s are fixed at known locations, their directions-of- arrival
(DOA’s) may easily be obtained and incorporated for adaptive beamforming without need to be tracked.
– Large cell in 802.22 networks also makes beam-forming problem simple
from 2D to 1D problem: easy DOA estimation (if necessary) or beamforming using a simple array.
– In conjunction with the transmit diversity in the forward link and/or
receive diversity in the reverse link, adaptive beam-forming may
significantly increase cell radius, as required for 802.22 systems.
– Adaptive beam-forming also significantly reduces multi-path delay
spread, which enhances system efficiency.
Submission
Slide 63
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Multiple Antenna Techniques for 802.22
Systems: Beam Forming
• Why adaptive beam-forming for 802.22 systems?
– Adaptive array system steers the main beam to the direction of a
desired signal, while steering nulls to the directions of undesired
interference signals.
adaptive array
fixed-beam
Fig. 1 Adaptive array vs. fixed-beam array.
Submission
Slide 64
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Transmit Diversity Options-summary
• Open Loop:
– STBC: Optimal only for 2 transmit antennae.
– Tone Interleaving: Performance gain is limited in channels with
high frequency diversity.
• Closed Loop:
– Eigen-beamforming at base-station: best performance, however
requires full down-link channel information at transmitter.
– Reduced-feedback methods: number of feedback bits can be
reduced, with ~ 1dB performance loss
Submission
Slide 65
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Transmit Diversity Performance
Submission
Slide 66
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
STBC-OFDM System
Cyclic prefix
IFFT
Binary
input data
Data
mapping
Cyclic
prefix
Removal
S/P
FFT
STBC
Encoding
Linear
Combiner

IFFT
P/S


Cyclic prefix
Data
demapping
h 1~ 4
Binary
output data
Fig. 3 Block diagram of an STBC-OFDM
system.
Submission
Slide 67
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Parameters for Vector Channel Model
• Channel Parameters for Simulation
(* : defined for adaptive beam-forming)
PROFILE A
Path 1
Path 2
Path 3
Path 4
Path 5
Path 6
Excess delay
0
3 sec
8 sec
11 sec
13 sec
21 sec
Relative amplitude
0
-7 dB
-15 dB
-22 dB
-24 dB
-19 dB
Doppler frequency
0
0.10 Hz
2.5 Hz
0.13 Hz
0.17 Hz
0.37 Hz
Incident angles*
0o
2.6o
-6.9o
9.5o
-11.2o
18.0o
0.68 sec
rms delay
PROFILE B
Path 1
Path 2
Path 3
Path 4
Path 5
Path 6
Excess delay
-3 sec
0
2 sec
4 sec
7 sec
11 sec
Relative amplitude
-6 dB
0
-7 dB
-22 dB
-16 dB
-20 dB
Doppler frequency
0.1 Hz
0
0.13 Hz
2.5 Hz
0.17 Hz
0.37 Hz
0o
2.6o
-4.3o
6.0o
-8.6o
12.0o
Incident angles*
0.83 sec
rms delay
Submission
Slide 68
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Parameters for Vector Channel Model
(cont.)
• Channel Parameters for Simulation (cont.)
(* : defined for adaptive beam-forming)
PROFILE C
Path 1
Path 2
Path 3
Path 4
Path 5
Path 6
Excess delay
-2 sec
0
5 sec
16 sec
24 sec
33 sec
Relative amplitude
-9 dB
0
-19 dB
-14 dB
-24 dB
-16 dB
Doppler frequency
0.13 Hz
0
0.17 Hz
2.5 Hz
0.23 Hz
0.10 Hz
0o
-0.86o
-3.0o
7.7o
-11.2o
15.0o
Incident angles*
1.07 sec
rms delay
PROFILE D
Path 1
Path 2
Path 3
Path 4
Path 5
Path 6
Excess delay
-2 sec
0
5 sec
16 sec
22 sec
28 sec
Relative amplitude
-10 dB
0
-22 dB
-18 dB
-21 dB
-7 dB
Doppler frequency
0.23 Hz
0
0.1 Hz
2.5 Hz
0.17 Hz
0.13 Hz
0o
-0.86o
-3.0o
7.7o
-10.3o
13.0o
Incident angles*
5.36 sec
rms delay
Submission
Slide 69
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Simulation Conditions for STBC
Processing
• Two Tx Antenna Case: Alamouti’s scheme
• Doppler Spectrum: quasi-stationary Doppler spectrum
defined for 802.16a
• Channel Estimation
–
–
–
–
Channel estimation performed by using the preamble
Partitioned MMSE using 16 sub-carriers
SNR in MMSE: 20dB
rms delay in MMSE: 9ms
• Others
– Two OFDM symbols used for forward link preamble
– Preamble symbol strength set to the average signal strength
– No channel coding employed
Submission
Slide 70
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Simulation Conditions for Adaptive Beamforming
• Antenna Array
– Array type: Linear equi-spaced array with half wavelength spacing
consisting of 8 antenna elements.
– Modified spatial smoothing is applied with the sub-array size of 7.
– Root-MUSIC is used to estimate the DOA’s of incident signals.
– All incident signals are assumed to have zero elevation angle.
• Channel Conditions
– Model for angular spread: Laplacian model
– All clusters are assumed to have the angular spread of 0.3o.
• Others
–
–
–
–
–
Submission
Coincidence rate for signal identification set to 80%.
No. of OFDM symbols for reverse link preamble is 1.
No. of sub-carriers assigned to users is 128.
No. of sub-carriers per sub-band is 16 for reference signal method.
No channel coding employed
Slide 71
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Performance Evaluation: Alamouti’s
Scheme (1)
0
10
Modulation = QPSK
No. of Rx Ant = 1
Tx Ant spacing = 10 l
o
Angular spread = 0.3
-1
Uncoded BER
10
-2
10
Performance gain:
2.5dB ~ 7dB
-3
10
Alamouti case
Profile A (=0.88)
Profile B (=0.84)
Profile C (=0.93)
Profile D (=0.93)
No diversity case
Profile A
Profile B
Profile C
Profile D
-4
10
-5
10
0
5
10
15
20
25
Eb/No
Fig. 7 BER performance of Alamouti’s scheme in 802.22
environments (No channel feedback, QPSK,  = 10l).
Submission
Slide 72
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Performance Evaluation: ABF Algorithms
(1)
Fig. 9 Comparison of the BER performance (INR = 25dB, interference
DOA’s =(20o, 30o), relative gains = (0dB, -6dB) ).
Submission
Slide 73
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Transmit Diversity Benefits
• 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
implemented 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.
Submission
Slide 74
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Transmit Diversity: Open Issues
• Channel model: does sufficient diversity exists to
indeed realize the gains?
• How often does channel feedback need to be send to
transmitter?
• Signaling format to allow transmit diversity (open and
close loop) options need to be specified at very start of
standardization process.
Submission
Slide 75
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Additional Physical Layer Features
• Ranging
• TPC
Submission
Slide 76
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Design Review: PHY Layer
 Checking the functional requirements for IEEE 802.22 WRAN
WRAN Functional
Requirements
Our Proposal
Minimum
Peak
Throughput
DL: 1.5 Mbps/subscriber
UL: 384 kbps/subscriber
DL: < 2.84 Mbps/subscriber
UL: < 2.13 Mbps/subscriber
Service
Coverage(*)
Typical: 33 km
Maximum: 100 km
Typical: 60.6 km(1K, 2K, 4K mode)
Maximum: 145.5km(8K mode)
Spectral
Efficiency
Minimum: 0.5 bits/s/Hz
Maximum: 5 bits/s/Hz
Minimum: 0.74 bits/s/Hz
Maximum: 5.20 bits/s/Hz
Maximum
Pre-echo: 3 us
Excess Delay Post-echo: 60 us
Maximum Cyclic Prefix Size:
 1K mode: 28 us
 2K mode: 56 us
 4K mode: 112 us
 8K mode: 224 us
(*) It is calculated from the point of view of TTG time, not from link budget.
Submission
Slide 77
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Spectrum Sensing
Submission
Slide 78
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Proposed Spectrum Sensing Scheme
•
•
Dual Sensing Strategy: Energy detection and Fine/Feature detection
Energy Detection
–
–
–
–
•
Fine/Feature Detection
–
–
–
–
–
•
•
•
To meet the speed and power requirement
Power spectrum distribution in the entire band is obtained
On request basis, detect the power level of selected channel in very short time
Examples are MRSS, RSSI
To meet the minimum sensitivity requirement
Fine sensing is applied for the selected channel
Feature Detection: detecting digital modulated signals
Examples include CSFD, field-sync detection,
FFT based spectral analysis: detecting narrowband analog modulated signals, most of part 74
devices
Distributed Sensing Strategy : Frequency usage information is collected and
managed at Base-station
Either the BS makes the detection decision based on the collective measurement
results or CPE’s can make the decision
Can be implemented as a stand alone sensing block with an omni-directional
antenna
Submission
Slide 79
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Spectrum Sensing Architecture
Omni Antenna
Fine/Feature
RFE
Control
MAC
Energy Detection
Submission
Slide 80
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Spectrum Sensing Strategy
Select candidates via
Energy Detection
•Sensing active channel during quite period
•Sensing non-active/candidate channels
•Scanning during initial startup
Fine/Feature detection
for a selected channel
Submission
Slide 81
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Energy Detection Method
•
•
Received signal strength within a given bandwidth is detected after the RF
receiver
Decision can be made by many different ways
– Analog/digital integration, MRSS, RSSI, FFT
•
•
•
Full range of spectrum profile can be obtained quickly with low power
consumption
Integration time and threshold is very important
BS sets essential parameters (constant)
Filter
Submission

LNA
Slide 82
Decision
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Cyclostationary Feature Detection
•
•
•
Large class of signals (eg., QAM, PSK, VSB, OFDM, CDMA, …) exhibit cyclostationary
Cyclic power spectrum provides a richer domain for signal analysis than conventional power
spectrum
Signal detection and classification
–
–
•
Stationary noise exhibits no cyclic correlations, while a signal of interest (eg., TV signal) being cyclostationary
exhibits unique spectral properties at cycle frequencies
Looking at cycle frequencies reveals specific ‘signal-only’ features
Better detector performance even in low SNR regions
Conventional spectrum density (left) vs cyclic
spectrum density (right) in high SNR conditions
(spectrum features at alpha = integer multiples
of symbol and carrier frequencies)
Conventional spectrum density (left) vs cyclic
spectrum density (right) in low SNR conditions
(spectrum features at alpha = integer multiples
of symbol and carrier frequencies)
Submission
Slide 83
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Cyclostationarity based signal detection
Signal attributes
x(n)
X T (n, f ) 
N / 21

p  N / 2
Sliding
N-pt
FFT
x(n  p)e
 j 2 f ( n  p )/ fs
Correlate and
average sum
Feature
detector
–Power
–Modulation
–Symbol frequency
1 M / 21
mfs  *
mfs 
S (n, f ) 
X T (n, f 
 ) X T (n, f 
 )

MN m M / 2
N 2
N 2

xt
• Cyclic spectrum domain reveals signal specific features at
– Modulating frequency
– Carrier frequency
– … (signal frequencies specific to modulation parameters)
• Various forms of detectors can be derived from cyclic power
spectrum density
Submission
Slide 84
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
DTV signal feature detection using field
sync/correlation
• Should not be sensitive to frequency selective fading,
and receiver impairments (e.g., frequency error)
• Use field sync correlation detection for ATSC, similar
correlation for other standards
– Compare correlation peak to the mean of the standard deviation of
the correlation
– Characterized the theoretical performance
– Experimental tests
Submission
Slide 85
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Experimental setup for DTV detection
8VSB_SOURCE
MULTIPATH SIMULATOR
RECEIVER
ATTENUATOR
Submission
Slide 86
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Based on Doc.: IEEE802.22-05/0055r7.
Profile A.
VSB SENSOR,
ENERGY SENSOR,
DELAY, DOPPLER, ATTEN, DETECTION RATE, % DETECTION RATE, %
dB
Hz
usec
PATH 1 POWER, dBm PATH 1 POWER, dBm
PATH 1
PATH 2
PATH 3
PATH 4
PATH 5
PATH 6
Submission
0
3.0
8.0
11.0
13.0
21.0
0
0.1
2.5
0.13
0.17
0.37
0
7.0
15.0
22.0
24.0
19.0
-107 -100 -90 -107
-100
-90
100
100
100
100
Slide 89
100
100
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Part 74 detection
• Part 74 devices occupy a small portion of the spectrum
• Thus, use spectral estimation and statistics of the
estimated signal
– Spectral estimation using FFTs (windowing techniques can also FFT
be
employed to better localize the spectrum)
• Perform FFT
• Average each freq bin
• Average across freq bin
1
P ( k , m) 
K
K 1
 Y ( k  i, m)
2
avg
i 0
N 1
 k   P ( k , m)
W.F.
m 0
N 1
 k   P ( k , m)   k
m 0
– Compute mean and “variance”
Submission
Slide 91
V>k*avg
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Part 74 detection (cont.)
• Detection
max( P(k , m))  k1  k  k 2  k
• Theoretical performance
Pr ob _ miss
  ( K , K ) M
Pr ob _ det ection  1  ( K , K ) M
Pr ob _ false _ alarm.  1  ( K , K ) N
Submission
Slide 92
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Narrow-band detection (Part 74): Theoretical and
simulated performance
Submission
Slide 93
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Probability of miss detection and false alarm
Submission
Slide 94
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
MRSS: Multi-Resolution Spectrum Sensing
• MRSS detect spectral components of incoming signal
by the Fourier Transform.
• Fourier Transform is performed in analog domain.
• MRSS may utilize wavelet transforms as the basis
function of the Fourier Transform.
• Bandwidth, resolution and center frequency can be
controlled by wavelet function
Submission
Slide 95
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
MRSS Schematics
Higher Layers: IP, ATM, 1394, etc.
Convergence Sublayer / Bridge (e.g., 802.1d)
MAC
MAC
PHY
PHY
PHY
PHY/MAC 1
PHY/MAC 2
PHY/MAC n
...
MAC
X
x(t)
Driver Amp
Spectrum Manager

z(t)
y(t)
ADC
CLK#2
w(t)
CLK#1
v(t)*fLO(t)
Timing
Clock
MAC
Wavelet
Generator
Submission
Slide 96
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Advantage of MRSS
• Full analog signal process
– Drastically reduce power consumption
– Faster recognition
•
•
•
•
Flexibility in sensing resolution and speed
Filter is not required on the sensing path
Wideband operation
Relaxing RF components constraint (Noise,
Linearity…)
Submission
Slide 97
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Non-linear effect of MRSS
• Effect of the RF Mixer for MRSS is simulated and
compared with Ideal multiplier
• Three input tone (240MHz, 470MHz, 600MHZ) is
assumed
• Hann window with 5MHz bandwidth is selected as the
wavelet
• RF circuit model of double balanced mixer is used as
multiplier
Submission
Slide 98
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Ideal Multiplier
Submission
Slide 99
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
LOmax = 10 dBm
Submission
Slide 100
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
LOmax = -30 dBm
Submission
Slide 101
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Result of MRSS
• Mixer non-linear effect is significantly depend on the
LO power level
• RF mixer can be used as the multiplier, if operating in
the linear mode
• By adjusting LO power for wavelet generator can
suppressing the unwanted harmonic component
Submission
Slide 102
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
MRSS Simulation Results
40
-50
20
-60
0
-70
-20
-80
PSD (dB)
Power Spectrum Magnitude (dB)
Wireless Microphone (FM) Signal
-40
-90
-60
-100
-80
-110
-100
0
0.2
0.4
0.6
0.8
1
1.2
Frequency
1.4
1.6
1.8
2
x 10
The spectrum of the wireless
microphone signal
Submission
-120
6
0
0.2
0.4
0.6
0.8
1
1.2
Frequency (Hz)
1.4
1.6
1.8
2
x 10
6
The corresponding signal spectrum
detected with the MRSS technique
Slide 103
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
OFDM
)
B
d
(
e
d
u
t
i
n
g
a
M
m
u
r
t
c
e
p
S
40
20
30
10
20
)
B
d
(
10
D
S
P
0
r
e
w -10
o
P
-20
-30
0
-10
-20
-30
0
0.5
1
1.5
2
2.5
3
Frequency
3.5
4
4.5
-40
5
7
x 10
Original
Submission
0
0.5
1
1.5
2
2.5
3
Frequency (Hz)
3.5
4
4.5
5
x 10
MRSS
Slide 104
7
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Presentation Outline
• Introduction
– A Glimpse of IEEE 802.22
• The PHY Proposal
• The MAC Proposal
• Conclusions
Submission
Slide 105
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
MAC Presentation Outline
• Introduction
• The MAC Protocol
– Protocol architecture
– MAC layer data communication
• Superframe and Frame Structures
• Network entry and initialization
• Downstream and Upstream scheduling
– Coexistence
•
•
•
•
Incumbents
Self-Coexistence
Synchronization of overlapping BSs
Clustering
– Security
• Performance Evaluation
Submission
Slide 106
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Introduction
• A MAC layer is proposed to be used for future IEEE 802.22
WRANs
• Some aspects of MAC have been inspired by the IEEE 802.16
MAC standard
• However, major enhancements have been made
– Support of multiple channel operation;
– Coexistence with both incumbents and itself (self-coexistence);
•
•
•
•
•
Incumbent user avoidance and Measurements (incumbents and itself)
Channel classification and Management
Dynamic resource sharing, Coexistence Beacon Protocol (CBP), and Etiquette
Synchronization of overlapping BSs
Embedded wireless microphone beacon mechanism
– Clustering support; etc.
Submission
Slide 107
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Overview
• Given the very long
propagation delays
in WRANs, the BS
regulates the
medium access (for
TDD/FDD)
– Downstream: TDM
(Time Division
Multiplexing)
– Upstream: DAMA
(Demand Assigned
Multiple Access)
TDMA
Submission
Packet Size: 50 bytes
Slide 108
Packet Size: 1500 bytes
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Overview (cont.)
• 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
– Defines a mapping between peer processes
– Defines a service flow (QoS provisioning)
Submission
Slide 109
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Protocol Stack Architecture
• Flexibility, scalability and efficiency are core elements
– Easy support of channel aggregation
– Channel grouping and matching
• Spectrum manager could be implemented in many ways
Higher Layers: IP, ATM, 1394, etc.
Convergence Sublayer / Bridge (e.g., 802.1d)
Submission
MAC
MAC
PHY
PHY
PHY
PHY/MAC 1
PHY/MAC 2
PHY/MAC n
...
Slide 110
MAC
Spectrum Manager
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Protocol Stack Architecture (cont.)
• Flexible and scalable channel assignment
1
2
3
4
5
Allocated
to PHY/
MAC 2
Allocated
to PHY/
MAC 3
Used by another 802.22 cell
Allocated
to PHY/
MAC 1
Used by another 802.22 cell
– Implementers decide on the algorithm
6
7
Frequency
Used by incumbents (e.g., TV stations)
Vacant and available for use by 802.22
Submission
Slide 111
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Grouping and Matching
• Multi-CH Resource Allocation
UL
DL
1
2
3
1’
N
2’
3’
N’
6MHz
MAP
DL
Burst#4
Burst#5
Burst#2
DL
Burst #3
time
Burst #1
MAP
Multi-FA Resource Allocation:
FA-1 MAP + FA-3 MAP
Burst #6
BS
1’
3’
1
3
MAP overhead for
Specifying multi-FA
allocation
3’
3
CPE 1
Submission
1’
1
Slide 112
3’
1’
3
1
CPE 3
CPE 2
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Grouping and Matching (cont.)
DL
1
2
UL
3
1’
N
2’
3’
N’
6MHz
CH-1 MAP
Burst#4
Multi-CH Resource Allocation by CH Grouping:
CH-1 MAP + CH-3 MAP
DL
Burst#5
Burst#2
DL
Burst #3
time
Burst #1
CH-3 MAP
Burst #6
CH
Matching
BS
CH
Matching
1’
3’
1
3’
CPE 1
3
3
CH Matching:
To select (UL and
DL) active set 1 for
individual CPE
Submission
CH Grouping:
To select a group of
CPE’s that are assigned
to the same channel
Slide 113
CPE 3
CPE 2
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Basic Terms and Definitions
• Superframe
– Defined and delimited by a preamble and the SCH (superframe control
header). It is comprised of a number of Frames
• Frame
– Comprised of one DS and one US Subframe, where BS and CPEs use to
communicate with each other
• Subframe
– Formed by a number of Bursts
• Burst
– Defined by a two dimensional segment of logical channel (frequency) and
MAC slot (time). It may comprise of multiple MAC PDUs belonging to
multiple CPEs
• MAC PDU
– The smallest unit of transmission/reception by the MAC. It is comprised
of the MAC header, the payload, and CRC
Submission
Slide 114
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Motivation for Channel Bonding
• The problem
– How to offer enhanced capacity and range?
• The fact
– 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 solution
– Simultaneous use of multiple contiguous TV channels
Submission
Slide 115
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Superframe Structure
...
Superframe n-1
Preamble
Superframe n
frame 0
SCH
...
Superframe n+1
...
frame 1
Time
frame m
Frequency
Superframe Control Header (SCH)
TV Channel
Preamble
t-1
• TV channels being bonded
• Coexistence and superframe information
• Number and size of Occupied
framesby Incumbent
• Information on periodic quiet periods
Occupied by Incumbent
• ID an transmit power of transmitter
SCH
•Location configuration information
TV Channel
Preamble SCH
t
Frame
0
Frame
1
...
Frame
m-2
(Quiet)
Frame
m-1
TV Channel
Preamble SCH
t+1
Preamble SCH
Frame
m
... Frame
0
Frame
1
Frame
n
Preamble SCH
Occupied by Incumbent
Time
Submission
Slide 116
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Frame Structure
• MAC is based on TDD/FDD frame structure
• The MAC frame structure is comprised of two parts
– A downstream (DS) subframe
– An upstream (US) subframe
Submission
Slide 117
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Time/Frequency Structure of a MAC
Frame
...
frame n-1
frame n
...
frame n+1
Time
MAC Slot Number
k
s
k+1
FCH
s+1
k+3
k+5
k+7
k+9
k+11
k+13
k+15
k+17
k+20
k+23
k+29
Burst CPE #1
UCS Notification
Burst CPE #3
Burst CPE #1
DS-MAP
Preamble
Burst CPE #2
Burst CPE #4
Selfcoexistence
BW Request
Burst CPE #2
TV Channel N
Selfcoexistence
s+2
Logical MAC Channel Number
k+26
Ranging
TV Channel N+1
Burst CPE #3
Burst CPE #5
Burst CPE #4
Burst CPE #5
Burst CPE #7
Burst CPE #6
Burst CPE #6
US-MAP
Burst CPE #8
Burst CPE #7
Burst CPE #9
Burst CPE #8
s+L
TTG
DS
Submission
US
Slide 118
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Network Entry and Initialization
• The key problem
Radio range of
TV station
Radio range of
802.22 BS
TV
station on
channel
#52
CPE 4
CPE 1
BS on
channel #52
CPE 2
CPE 3
Grade B contour
of TV station
Submission
Slide 119
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Network Entry and Initialization (BS)
• 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
Submission
Slide 120
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Network Entry and Initialization (CPE)
1.
2.
3.
4.
5.
6.
7.
8.
9.
Scan channels searching for a BS.
Once SCH is received, ascertain that the use of the channel(s) is
permitted (i.e., does not interfere with incumbents).
Synchronize to the BS.
Obtain the transmit parameters from the BS, which are
contained in the UCD message.
Perform ranging and Negotiate basic capabilities.
Authorize CPE and Perform key exchange.
Perform registration.
If indicated as desired by the CPE during registration (REGREQ message), perform other optional initialization procedures
such as establish IP connectivity, establish time of day, and
transfer operational parameters.
Set up connections.
Submission
Slide 121
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Network Entry and Initialization (CPE)
Wait for downstream
synchronization
Energy level
detected on
channel N is
above detection
threshold?
Start
Downstream
synchronization
established
Yes
Start Timer
Downstream:
Upstream:
Search for PHY
superframe starting
on channel N
PHY superframe
detected
Obtain upstream
parameters
Timeout (T12)
UCD
Timeout
No
Start Timer (Lost
SCH)
Yes
Ascertain the presence
of incumbent service in
channel N and other
affected channel(s)
Upstream
channel
usable?
If
measurements
are reliable?
No
Start Timer
Yes
Scan for downstream
channel
Operation
possible?
Mark upstream
channel usable
Yes
Search for PHY frame
on indicated BS
channel(s)
No
Disregard
channel
PHY frame
detected
Mark upstream
channel unusable
No
If notification
is allowed?
Timeout
Upstream
parameters
obtained
Yes
No
Send
coexistence
beacon
Reset (T12)
Start Timer
Wait for DS-MAP
Start Timer (T12)
DS-MAP received
Timeout
Move to next channel
(e.g., N = N+2)
Start Timer (Lost DSMAP)
Start Timer (T1)
Downstream
synchronization
established
Submission
Start Timer (Lost USMAP)
Start Timer (T12)
Synchronized
Maintain upstream
Slide 122
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Downstream (DS) Transmissions
• DS = core messages + data (transmitted in bursts)
– Two core DS messages: DCD and DS-MAP
– Bursts identified by DIUC (Downstream Interval Usage Code)
– Each burst may contain data for several CPEs
• DCD (Downstream Channel Descriptor)
– Establishes association between DIUC and actual PHY parameters (e.g.,
modulation and coding)
• DS-MAP (Downstream map)
– Defines the usage (i.e., scheduling) of the downstream
– Critical, hence first message in each frame
– For self-coexistence purposes, the BS may choose to use part of DS
subframe for CBP protocol operation
Submission
Slide 123
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Upstream (US) Transmissions
• US = core messages + data (contention and bursts)
– Two core DS messages: UCD and US-MAP
– Bursts identified by UIUC (Upstream Interval Usage Code)
– The upstream can be segmented into several UIUC
• Contention-based
– Initialization, Bandwidth Request, Urgent Coexistence Situation (UCS), CBP slots (SCS)
• Data Bursts
• UCD (Upstream Channel Descriptor)
– Establishes association between UIUC and actual PHY parameters (e.g.,
modulation and coding)
• US-MAP (Upstream map)
– Defines the usage (i.e., scheduling) of the upstream
– Contains “grants”addressed to a particular CPE or a set of CPEs (e.g., for
self-coexistence)
Submission
Slide 124
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Bandwidth Management: Request/Grant
Scheme
• Self correcting
– No acknowledgement
– All errors are handled the same way (i.e., periodic aggregate requests)
• Bandwidth requests
– Are always per connection
– Can specify DS/US Traffic Constraint IEs for better self-coexistence
• Bandwidth grants
– Can be either per connection or per CPE
– Grants (given as durations) are carried in US-MAP messages
– CPE converts time into amount of data using information about the UIUC
Submission
Slide 125
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Scheduling Services
• Unsolicited Grant Services (UGS)
– For CBR and CBR-like flows (T1/E1)
– No specific bandwidth request issued by CPE
• Real-time Polling Service (rtPS)
– For rt-VBR-like service flows such as MPEG video
– CPEs are polled to meet delay requirements
• Non-real-time Polling Service (nrtPS)
– For non-real-time flows with better than best effort service such as
bandwidth-intensive file transfer
– CPEs are polled and can use contention interval
• Best Effort (BE)
– E.g., Web surfing
– CPEs use contention interval only
Submission
Slide 126
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
MAC Presentation Outline
• Introduction
• The MAC Protocol
– Protocol architecture
– MAC layer data communication
• Superframe and Frame Structures
• Network entry and initialization
• Downstream and Upstream scheduling
– Coexistence
•
•
•
•
Incumbents
Self-Coexistence
Synchronization of overlapping BSs
Clustering
– Security
• Performance Evaluation
Submission
Slide 127
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Coexistence
• Two primary types
– With incumbents (TV service and Part 74 devices)
– With other overlapping 802.22 cells
• Self-Coexistence
• Measurements can be classified as:
– In-band
• In case of incumbents, requires quiet periods (QP)
– Out-of-band
• No need for quiet periods
• Coexistence is achieved by a joint application of:
– Spectrum management (frequency and power)
– “Interference-free” traffic scheduling (time)
Submission
Slide 128
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Measurements
• Measurements form a key component of the MAC
– Protection of incumbents and self-coexistence
• The BS may request multiple measurements in a single
management message
– E.g., ATSC, DVB, Wireless Microphone, 802.22
• Measurement messages may be transmitted through
multicast
– Allows the implementation of advanced features such as clustering
– Bandwidth efficient
Submission
Slide 129
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Measurements (cont.)
• Bulk Measurement Request (BLM-REQ)
– Transmitted by the BS to CPEs
– Includes information such as
• Channels to measure
• Multiple single measurement requests
• Bulk Measurement Response (BLM-RSP)
– Transmitted by CPE to BS
– If needed, acknowledges the receipt of the BLM-REQ message
• Bulk Measurement Report (BLM-REP)
– Transmitted by CPE to BS
– Returns multiple single measurement reports
• Bulk Measurement Acknowledgement (BLM-ACK)
– Transmitted by BS to CPE
– Acknowledges receipt of measurement report
Submission
Slide 130
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Measurements (cont.)
• Single measurements can be of various types
– Signal specific measurement request
• TV system and Wireless microphones
– Beacon measurement request
• CBP, BS, and Wireless microphone beacons
– CPE statistics measurement request
– Stop measurement request
– Location configuration measurement request
• A range of parameters can be specified
n measurement
repetitions
1
2
. . .
n
Time
Duration
Submission
Restart Delay
Randomization
Interval
Slide 131
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Measurements (cont.)
• There is almost a one-to-one correspondence between
measurement requests and reports
• Some of the individual reports are:
– Signal specific measurement report
• TV/Wireless Microphone system type, measured value, precision, etc.
– Beacon measurement report
• Information on any CBP, BS, or Wireless microphone beacons
received
– CPE statistics measurement report
• E.g., Packet error rate
– Location configuration measurement report
• If known, location information (GPS, triangulization, and so on)
Submission
Slide 132
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Management
• Channel management is key to effective network coordination,
coexistence and sharing
• Included in two modes
– Embedded
– Non-embedded
• A set of messages are defined to allow flexible management of
channels, including:
– Add/remove channel(s) to/from current set of channels
– Switch channel(s) of operation
– Quiet selected channel(s) – possibly to perform in-band measurement
Submission
Slide 133
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Management (cont.)
• Channel Set: Definitions
-
Active set 1: a set of used channels for a certain CPE
Active set 2: a set of used channels for a certain BS
Candidate set: a set of clean channels available for a certain CPE or BS
Occupied set: a set of occupied channels by incumbent user which a certain CPE finds
Disallowed Set: a set of channels whose access are not allowed by regulation
Null set : a set of channels that are not classified as one of above five sets
* Note: The allowed set is defined by union of candidate set and null set depending on
channel’s SIR level
• Channel Set Maintenance
- Each BS maintains five channel sets: Active 1, Active 2, Occupied, Candidate, Null
- Each CPE maintains four channel sets: Active 1, Active 2, Candidate, Occupied
- If needed, each set is updated every quiet period (periodic or aperiodic)
Submission
Slide 134
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Management (cont.)
•
Transition diagram for channel set
 The channel becomes useless as
incumbent service appears.
 Incumbent service releases the channel
and its quality is good, then it is classified as
a member of candidate set.
 Incumbent service releases the channel
and its quality is poor, then it is classified as
a member of null set.
 If the channel quality is better than an
existing member of the candidate set, then it
replaces the member of candidate set.
 The channel becomes active as quality
goes above a given threshold.
 The channel is classified as a member of
null set as quality goes below a given
threshold.
 The channel is released due to the finish
of its usage.
Submission
Slide 135
Null Set
6
6
3
4
1
Active Set
5
7
1
1
Candidate Set
Occupied Set
2
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Coexistence with Incumbents
• Accomplished through the following steps:
– Measurements (discussed earlier)
– Detection
• TV: For more info, please see PHY proposal.
• Wireless Microphones
– PHY solution: For more info, please see PHY proposal.
– MAC solution: See next slide.
– Incumbent Notification
– Incumbent Detection Recovery
Submission
Slide 136
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Coexistence with Incumbents
• Accomplished through the following steps:
– Measurements (discussed earlier)
– Detection
• TV: For more info, please see PHY proposal.
• Wireless Microphones
– PHY solution: For more info, please see PHY proposal.
– MAC solution: See next slide.
– Incumbent Notification
– Incumbent Detection Recovery
Submission
Slide 137
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
MAC Layer Detection of Wireless
Microphones
• From the transmitter perspective, wireless microphone beacons
(WMB) can be of two types
– Embedded
• 802.22 device which has the additional capability of emitting WMBs
– Non-embedded
• Currently addressed by the Part 74 Task Group
• Based on the proposed MAC layer, we have developed an
embedded WMB approach that:
– Reliably detects multiple collocated 802.22 networks
– Upon sending WMBs, this mechanism causes minimal, if any, harmful
interference to collocated 802.22 networks
– Once either BSs or CPEs detect the WMB, a dissemination is made and all
present 802.22 networks vacate the channel
Submission
Slide 138
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Notification
• The problem
– How CPEs notify the BS about the presence of
incumbents in a timely fashion?
• Two modes are proposed:
– Explicit Notification is executed first
– Implicit Notification in case Explicit Notification fails
Submission
Slide 139
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Notification:
Explicit Mode
• Two solutions are possible
– CPEs with upstream bandwidth allocation
• Send report provided bandwidth and time are available; and
• Set dedicated bits in MAC header
– CPEs without upstream bandwidth allocation
• Urgent Coexistence Situation (UCS) Notification slots reserved
specifically for incumbent notification purposes
– Can use either contention-based or contention-based CDMA access
• The size of a slot fits the smallest MAC frame necessary to perform
the incumbent notification: the MAC header
• In both solutions, there is NO need to wait for a quiet
period (QP) before recovery
– CPEs can notify the BS at any point
Submission
Slide 140
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Notification:
Explicit Mode (cont.)
...
frame n-1
frame n
...
frame n+1
Time
MAC Slot Number
k
s
k+1
FCH
s+1
k+3
k+5
k+7
k+9
k+11
k+13
k+15
k+17
k+20
k+23
k+29
Burst CPE #1
UCS Notification
Burst CPE #3
Burst CPE #1
DS-MAP
Preamble
Burst CPE #2
Burst CPE #4
TV Channel N
TV Channel N+1
Burst CPE #3
Burst CPE #5
Burst CPE #4
Burst CPE #5
Burst CPE #7
Burst CPE #6
Burst CPE #6
US-MAP
Burst CPE #8
Burst CPE #7
Burst CPE #9
Burst CPE #8
s+L
TTG
DS
Submission
Selfcoexistence
BW Request
Burst CPE #2
Selfcoexistence
s+2
Logical MAC Channel Number
k+26
Ranging
RTG
US
Slide 141
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Notification:
Explicit Mode (cont.)
• The BS can use various strategies depending upon how
reliable it wants the notification to be
– Trade-off between overhead and data efficiency
– Scalability
n Quiet
Periods
1
2
. . .
n
Time
Duration
Quiet Period
Notification Phase
Submission
Normal System Operation
Notification Phase
Slide 142
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Notification:
Implicit Mode
• When the BS (CPE) does not receive expected
communication from CPE (BS) within a pre-defined
timeout
• Then, the BS (CPE) assumes that an incumbent user
has appeared in the channel
Everything looks fine,
so let me keep it up….
집
I found IU just had appeared,
so I now have to search for new band….
By the way, do he know about that?
Submission
Slide 143
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Notification:
Implicit Mode (cont.)
• Short Implicit
BS
• Normal Implicit
CPE
BS
U
QP
Fx:MAP
QP
D
QP
Fx:Null
Time-out
Fx:MAP
Fx:Null
Fx:MAP
Fx:Null
..
.
Fz:MAP
QP
Fz:MAP
..
.
..
.
Initialization
Fz:MAP
Fz:MAP
QP
Fz:MAP
BLM-REP
Fz:MAP
QP
BLM-REP
Fz:MAP
Submission
Fz:MAP
Slide 144
..
.
Initialization
QP
Time-out
CPE
QP
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Detection Recovery
• The problem
– How does the 802.22 cell recover from an incumbent appearance
in a timely fashion?
Submission
Slide 145
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Incumbent Detection Recovery (cont.)
• The Incumbent Detection Recovery Protocol (IDRP)
– Introduces the concept of Candidate/Backup Channel(s)
– The 802.22 network not only performs in-band measurements, but
also out-of-band measurements
• Out-of-band measurements will determine suitable Candidate/Backup
Channel(s)
– The 802.22 network falls back to a Candidate/Backup Channel in
case communication is preempted by an incumbent
– The algorithms at both the BS and CPEs are provided
• These algorithms also account for the case when no Candidate/Backup
Channel is available
Submission
Slide 146
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Self-Coexistence
• The general problem
TDMA Schedule
Submission
Slide 147
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Self-Coexistence (cont.)
• Indeed a major issue
– E.g., 802.16h
• Becomes even more
critical in 802.22 given
– The large coverage
range
– Its unlicensed nature
• Directional antennas at
CPEs do not address
the problem
Submission
Slide 148
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Self-Coexistence (cont.)
• Some approaches to better self-coexistence
– Over the backhaul (i.e., wired)
• Pros
– 802.22 can wash its hands (throw the “hot potato” to somebody else)
• Cons
– Will there be really a “common backhaul” between competing WISPs? Can 802.22
rely on that?
– What if this “common backhaul” is down?
– Can 802.22 rely on the “upper layers” to take care of self-coexistence?
– Coordination is an active process (e.g., quiet periods), and not a “once-in-a-month
thing”
– Over-the-air
• Pros
– Built-in and self-healing 802.22 system
• Cons
– More complex MAC layer (but just a little more)
Submission
Slide 149
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Self-Coexistence (cont.)
• Two solutions are proposed
– BS beacon based
– The Coexistence Beacon Protocol (CBP), which enables
• Sharing in time and frequency
• Dynamic resource offering and renting
• Etiquette for channel assignment
• Both solutions:
– Can be implemented either over-the-air or via a backbone
• Here, we focus on the over-the-air implementation
– Allow either one-way or two-way (i.e., negotiation) communication
• The BS and its CPEs shall participate in the self-coexistence task
Submission
Slide 150
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Self-Coexistence (cont.)
•
BS beacon based
Case 1:
– Implemented through
overheard BS beacons
– BS beacons carry various
information:
•
•
•
•
Channels used
Quiet periods
Frame information
Transmit power level
Case 2:
– If needed, can use sensing
antenna for this purpose
– Allows better TPC and
sharing in frequency only
Submission
Slide 151
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Self-Coexistence (cont.)
•
Coexistence Beacon
Protocol (CBP)
– CBP is executed by CPEs
but under BS control
– CPEs transmit coexistence
packets with information
about
CBP beacon
CBP beacon
• The cell
• This CPE’s reservations
with the BS
• Resource request
• Channels from the active
and candidate sets
– Allows better TPC and
sharing in both frequency
and time
Submission
Slide 152
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Self-Coexistence (cont.)
...
frame n-1
frame n
...
frame n+1
Time
MAC Slot Number
k
s
k+1
FCH
s+1
k+3
k+5
k+7
k+9
k+11
k+13
k+15
k+17
k+20
k+23
k+29
Burst CPE #1
UCS Notification
Burst CPE #3
Burst CPE #1
DS-MAP
Preamble
Burst CPE #2
Burst CPE #4
Selfcoexistence
BW Request
Burst CPE #2
TV Channel N
Selfcoexistence
s+2
Logical MAC Channel Number
k+26
Ranging
TV Channel N+1
Burst CPE #3
Burst CPE #5
Burst CPE #4
Burst CPE #5
Burst CPE #7
Burst CPE #6
Burst CPE #6
US-MAP
Burst CPE #8
Burst CPE #7
Burst CPE #9
Burst CPE #8
s+L
TTG
DS
Submission
US
Slide 153
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
But what does the CPEs do with this
information?
• Report it to its associated BS
• Future upstream bandwidth reservation requests can
contain time allocation constraints
– For example, a CPE can specify: “Give me 100Kb of airtime, but
not between T1 and T2”
• Note on the BS
– Traffic Constraint (TRC-REQ/RSP) management messages are
also available to the BS
• For example, can be used before the BS allocates any time for the CPE
• Allow the BS to inquire CPE about possible time allocation
constraints
Submission
Slide 154
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Then, what does the BS do about all this?
• If possible and desirable,
avoid each other by
switching channels
• Better TPC
• Implement
“interference-free”
scheduling
– Sharing in time and
frequency
• In case of Resource
Request
– Following CBP packets
contain channels from
the active/candidate sets
Submission
Slide 155
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Resource Renting
• When
– A BS (Offerer) already acquired TV channels, and if other BSs
(Renter) cannot secure the required resource (in the case where
vacant TV Channels are not available)
• Then
– Renter can request a resource partition to the Offerer
• Resource partition ratio between different BSs is outside of this
proposal (pre-determined)
Submission
Slide 156
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Resource Offering
• Step-by-step procedure between Offeror and Renter
–
–
–
–
–
1) Offeror broadcasts its unused TV channel(s)
2) Renter requests its desired TV channel(s) and usage duration
3) Offeror confirms the allocation
4) Renter sends back an ACK
5) Renter shall return the borrowed resource before the rental
duration expires
Resource
Advertisement
Resource
Renting Response
Offeror
Resource
Renting Request
Resource
Renting ACK
Renter
Submission
CBP
CBP
Slide 157
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Etiquette for Channel Assignment
• The renter-offerer mechanism is used to gather channel
usage information in neighboring BSs
• The etiquette is then used to select the appropriate
channel that minimizes interference among
collocated/neighboring WRANs
Submission
Slide 158
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Etiquette Example
N2:
1,5,6
N1:
1,2,3
1,3,4,6,7
N3:
1,4,8
Active Set
Neighbor 1
Neighbor 2
Neighbor 3
1,2,3
1,5,6
1,4,8
Central
U (Candidate sets)
1,3,4,6,7
1st Selection
7
2nd Selection
4 (randomly from 3,4,6)
Final Selection
3 (randomly from 3,,6)
Submission
Slide 159
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Synchronization of Overlapping BSs
• The problem
– Frames of co-channel overlapping BSs are asynchronous, which makes
coexistence even harder
BS1:
BS2:
frame 0
...
frame 1
frame 0
frame 1
frame m
...
frame m
Time
• Numerous benefits to synchronization
– Incumbent protection
• Quiet period synchronization of overlapping BSs
• Improved detection
– Self-Coexistence
• Logical channel amongst overlapping BSs
• Efficient sharing of resources
Submission
Slide 160
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Synchronization of Overlapping BSs (cont.)
•
Synchronization is proposed amongst multiple collocated 802.22 networks
MAC Slot Number
k
s
k+1
FCH
k+5
k+7
k+9
k+11
k+17
k+15
k+20
k+23
k+29
k+26
UCS Notification
Burst CPE #1
BW Request
s+2
DS-MAP
Burst CPE #3
s+L
Burst CPE #2
Burst CPE #1
Burst CPE #2
US-MAP
Preamble
Frame n at BS1:
k+13
Selfcoexistence
Logical MAC Channel Number
s+1
k+3
Burst CPE #3
Burst CPE #5
Burst CPE #4
Burst CPE #4
TTG
CBP packets
s
FCH
UCS Notification
Burst CPE #1
BW Request
s+2
s+L
DS-MAP
Burst CPE #2
Burst CPE #1
Burst CPE #2
US-MAP
Preamble
Frame m at BS2:
Burst CPE #3
Burst CPE #4
Selfcoexistence
Logical MAC Channel Number
s+1
Burst CPE #3
Burst CPE #5
Burst CPE #4
TTG
Time
Submission
Slide 161
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Clustering
• Alleviate much of the redundancy
involved in the execution of the
coexistence mechanisms
– So, very suitable for 802.22
– Can be employed in all coexistence
mechanisms, except for the protection
of Wireless Microphone services
• Based on key observations
Cluster
CPE
BS
– Sensing outcome of close-by CPEs are
likely to be “similar”
– CPEs are stationary
• It is a two-step process conducted by
the BS
– Formation of Physical Cluster
– Formation of Logical Cluster
Submission
Slide 162
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Clustering: Physical Cluster (cont.)
• Creation of Physical
Clusters is totally localized
at the BS
Physical
Cluster
CPE
– No direct involvement from
CPEs
BS
• The BS groups together
CPEs sensing “similar”
characteristics of the
incumbent signal
– Could also be based on location
relative to the incumbent
transmitter
Submission
Slide 163
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Clustering: Physical Cluster (cont.)
• Based on the well-known kmeans clustering algorithm
• The algorithm
Received incumbent
signal strength
– Initially, no clustering
– CPEs report measurements to
the BS (BLM-REP) which
constructs incumbent profiles
– Then, the BS runs the
clustering algorithm
Nearby (or
high power)
incumbent
Far away (or
low power)
incumbent
Frequency
Submission
Slide 164
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Clustering: Logical Cluster (cont.)
Physical
Cluster
• Formed by CPEs
belonging to different
Physical Clusters
CPE
• Allows the BS to group
those CPEs that are less
likely to contend for the
same airtime
BS
• CPEs within a Logical
Cluster perform the same
“coexistence task”
Logical
Cluster
Exemplary assignment for
incumbent measurements:
ATSC
Submission
Slide 165
NTSC
Exemplary assignment
for CBP:
DVB
All
CBP at T1
CBP at T2
CBP at T3
Martial Belec, France Telecom
All
January 2006
doc.: IEEE 802.22-06/0009r0
MAC Presentation Outline
• Introduction
• The MAC Protocol
– Protocol architecture
– MAC layer data communication
• Superframe and Frame Structures
• Network entry and initialization
• Downstream and Upstream scheduling
– Coexistence
•
•
•
•
Incumbents
Self-Coexistence
Synchronization of overlapping BSs
Clustering
– Security
• Performance Evaluation
Submission
Slide 166
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Security Sublayer
• Based on IEEE 802.16e/D12 security sublayer
– Generic security framework made specifically for BWA networks
– Meets all the security requirements identified for the 802.22
WRAN Standard
– Deeply studied and improved by various security experts
(including IEEE and IETF ones)
• Composed of two sublayers
– A Privacy Key Management protocol (PKM) which provides
authentication, authorization and secure key distribution between
the BS and the CPE
– An encapsulation protocol which provides data packets protection
Submission
Slide 167
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Security Sublayer (cont.)
• Mutual Authentication of the devices
– Either using RSA and digital certificates
– Or using EAP and EAP-method specific credentials
• Authentication of the subscribers (optional)
– Using EAP and EAP-method specific credentials
• Authorization based on authenticated CPE and/or
subscriber identity
– Give access to dedicated service flows
Submission
Slide 168
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Security Sublayer (cont.)
• Data packets encryption
– Using strong cryptographic algorithms (AES)
• Management frames integrity protection
– Using keyed message authentication codes
• Protection against Deny of Service and other attacks
–
–
–
–
Submission
Protection of management frames against forgery and replay attacks
Protection of data frames against replay attacks
Protection of EAP packets during subscribers authentication
Protection of every key negotiation phase, using digital signatures and
random numbers
Slide 169
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
MAC Presentation Outline
• Introduction
• The MAC Protocol
– Protocol architecture
– MAC layer data communication
• Superframe and Frame Structures
• Network entry and initialization
• Downstream and Upstream scheduling
– Coexistence
•
•
•
•
Incumbents
Self-Coexistence
Synchronization of overlapping BSs
Clustering
– Security
• Performance Evaluation
Submission
Slide 170
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Performance Evaluation
• All aspects of the MAC are being implemented in OPNET
– OPNET is considered the most well-reputated and reliable network
simulation tool available today
• In all simulations:
– In case of quiet periods (QP), every CPE performs detection in all in-band
channels (e.g., N-1, N, and N+1 in case of a single TV channel)
– DFS model is implemented as per the requirements document
– No fragmentation or packing
• Some common simulation parameters
–
–
–
–
Submission
Superframe size = 12 frames, where Frame size = 40 ms
Packet size = 1 Kbyte
Detection time per TV channel = 13 ms
64-QAM rate 2/3 and Symbol time = 310 µs
Slide 171
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Throughput at the MAC SAP
• Evaluate the throughput of
the MAC under varying
number of bonded TV
channels
• 1 BS and 127 CPEs
Submission
Slide 172
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Throughput at the MAC SAP (cont.)
• Impact of QP on
throughput is
more confined to
high load
scenarios
– The scheduler can
properly handle
this
• Channel bonding
provides
significant
performance
improvement
Submission
Slide 173
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Channel Efficiency
• Evaluate the
channel
utilization
– The overall
impact of QPs
is only
noticeable in
high loads
• Fragmentation
and packing can
improve these
figures even
more
Submission
Slide 174
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Network Joining Time
• Evaluate, for the worst case
scenario, the average network
joining time by a CPE
– CPEs first scan channel for a
time equivalent to a frame size
– CPE stays in a channel for a
superframe duration after that
– This is followed by network
entry and initialization
• More efficient algorithms can
be easily implemented
Submission
Slide 175
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Network Joining Time (cont.)
• 1 BS and 127
CPEs
– BS is powered
up at
simulation
startup
– CPEs power
up at random
times
• 802.22 FRD
requires joining
time under 10
sec
Submission
Slide 176
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Impact on QoS
•
Evaluate the impact of quiet
periods and incumbents on QoS
•
Traffic pattern
– A total of 3 Mbps constant
aggregate US traffic
– DS traffic varies between 3 Mbps
and 15 Mbps
•
All 127 CPEs establish
connections with BS
– Out of these, 4 real time (QoS)
connections at 32 Kbps each
– Other connections are BE or nonreal time
Submission
Slide 177
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Impact on QoS (cont.)
Effect of Queuing
(sec)
• The overall
impact on
average
downstream
delay is very
small
– QoS can be
satisfied to a
large extent
Submission
Slide 178
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
• The overall
impact on
average
upstream delay
is not so small
as in the
downstream
case
(sec)
Impact on QoS (cont.)
– Despite of
that, QoS can
still be
satisfied to a
significant
extent
Submission
Slide 179
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Handling of Incumbents
• Evaluate the detection,
notification and recovery
capability of the MAC
• 1 BS and 9 CPEs
• TV station starts in-band
operation at a random time
– Incumbent is detected
during quiet period
Submission
Slide 180
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Handling of Incumbents (cont.)
• Network operation
is quickly restored
– BS and unaffected
CPEs switch to
Candidate/Backup
Channel
Channel A
Channel B
– CPEs who do not
receive switch
message go to
Candidate/Backup
Channel after
timeout (2 frames)
Submission
Slide 181
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Handling of Incumbents (cont.)
• Evaluate the
dynamics of
channel bonding
Channel A
Channel B
– Together with
handling of
incumbents
– Network can
switch to one or
more
Candidate/Backup
Channel
Submission
Slide 182
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Presentation Outline
• Introduction
– A Glimpse of IEEE 802.22
• The PHY Proposal
• The MAC Proposal
• Conclusions
Submission
Slide 183
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Conclusions
• Proposed a PHY and MAC that addresses 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.
Submission
Slide 184
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Appendix A
• WRAN maximum transmit power constraint
for interference management and coexistence
Submission
Slide 185
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Place of proposed interference
management module in the system
Sensing measurements
Radio map
Footprints of incumbent
and coexisting WRANs
Database
Module that
computes the
constraints
relative to the
protection of
incumbents
Module that
computes the
constraints
relative to
coexistence
Set of minimum
constraints for QoS
scheduler
optimization
QoS scheduling & resource allocation (RRM):
• in opportunistic spectrum access channels
• in dedicated channels (for coexistence)
Interference management module
Constraints from WRANs negotiation outcome
Submission
Slide 186
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Joint maximum power constraint rule in
constraint areas
WRAN BS
Limit of service provision whenever
channel N is occupied by TV
operation by this TV station
P = 4W if alone
P=0
P < 4W
P=0
P=0
d
P < 4W
CPE
Joint maximum power
constraint rule in this
constraint area
150 m
P=0
NTSC TV transmitter
in Channel N
Grade B
4.7 km
dmin
Submission
Slide 187
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
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.
Submission
Slide 188
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Step by step process for the determination of the
interference protection constraints
Spectrum usage map
Distance/location information
Incumbent presence information
Table 1 of max powers for each CPE on
all TV bands
Table 2 of max powers for all CPEs on
all TV bands
First layer of individual maximum transmit power constraints
Using flowchart #1 and EIRP information
Second layer of individual maximum transmit power constraints
List of areas where simultaneous transmissions are critical
List of CPEs in these areas and density of constraint area
Negotiation between WRANs:
• sharing of density and area information
• result of negotiation:
• dedicated channels (operating
and backup)
• shared channels
Computation of maximum transmit power control rules for the
CPEs in each constraint area
Power density of other unlicensed users
in each constraint area
Distance and area information
Third layer of maximum transmit power constraints
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
Submission
Slide 189
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
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)
TV band
CPE operation
on
TV band 1
1
No TV
2
TV
3
No TV
4
TV
5
No TV
6
No TV
7
TV
Outside grade B
Distance
Inside grade B
Outside grade B
Distance
Outside grade B
Distance
Inside grade B
Outside grade B
Distance
Inside grade B
4W
4W
4W
Not allowed
(adjacent band)
4W
8
No TV
4W
EIRP(-6)
4W
4W
EIRP(-5)
4W
4W
EIRP(-4)
4W
CPE Operation not allowed
TV band 2
4W
Not allowed
4W
4W
4W
1st layer of maximum
power constraint
CPE Operation not allowed
TV band 3
4W
Not allowed
(adjacent band)
4W
EIRP(+2)
4W
4W
@ 150 m DTV
@ 44 m NTSC
4W
2nd layer of maximum
power constraint
CPE Operation not allowed
TV band 4
4W
4W
@ 10 m DTV
@ 4.7 km NTSC
4W
4W
EIRP(-3)
4W
CPE max transmit power = min{ EIRP(+2), EIRP(-3), 4W }
TV band 5
4W
EIRP(+3)
TV band 6
4W
EIRP(+4)
4W
4W
@ 150 m DTV
@ 31 m NTSC
4W
4W
EIRP(-2)
4W
To Table 2
CPE max transmit power = min{ EIRP(+3), EIRP(-2), 4W }
4W
4W
4W
4W
Not allowed
(adjacent band)
4W
4W
Not allowed
4W
CPE Operation not allowed
TV band 7
4W
EIRP(+5)
4W
4W
4W
CPE Operation not allowed
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.
Submission
Slide 190
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Table 2 (example)
CPE
CPE #1
Constraint Area #1
CPE #2
Contraint Area #1
CPE #3
Area #2
TV band 1
Not allowed
Not allowed
x
TV band 2
Not allowed
Not allowed
x
TV band 3
Not allowed
Not allowed
x
TV band 4
EIRP(-3) or power control if not alone
(Outside grade B operation at distance d1)
EIRP(-3) or power control if not alone
(Outside grade B operation at distance d2)
x
CPE operation on
Individual or joint maximum power constraint rule might be required
TV band 5
EIRP(+3)
EIRP(+3)
x
TV band 6
Not allowed
Not allowed
x
TV band 7
Not allowed
Not allowed
x
Joint power constraint rule applies whenever CPEs share the same frequency band.
Submission
Slide 191
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Flowchart to determine the first layer of maximum
transmit power constraints  fill one cell of Table 1
start
TV
operation
in band
N?
No
Max power = 4W
DTV
No
Max power = 4W
CPE in
noiseprotected
contour +
150 m?
For one given CPE, determine the
constraints on all bands incurred by
possible TV operation on band N
Yes
NTSC
DTV or NTSC?
Yes
CPE in
grade B
contour +
150 m?
Yes
No
No
• add to list of disallowed bands: N-1, N, N+1
• set max power constraint from EIRP(DTV) on
other bands
Yes
Distance > 4.7 km?
Max power = 4W
Update Table 1
No
Distance > d_min?
no transmission on
channel N
Submission
Slide 192
Yes
limit max transmit
power as a function of
distance
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Simple description of the power rule
•
A single transmitting CPE induces power at TV receiver:
Pr = Pt d - a
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 decreased
Maximum transmit power rule:
Pt ,k = Pt (n , dk , Pt ,k ,max (dk ))
Power at the nearest TV receiver:
Pr =
å
dk- a Pt (n , dk , Pt ,k ,max (dk ))
k
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.
Submission
Slide 193
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Power constraint rule properties
A: constraint area
nmax: maximum allowed CPEs density
Submission
Slide 194
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
Appendix B
• Coexistence with other LE systems
(Contention-Based Protocol)
Submission
Slide 195
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
DS Contention-Based Coexistence with LE Devices
(Call Flow)
Primary BS
CPE
Normal data transmitting
Detect LE devices
Contention needed
Contention
Data transmitting in contention manner
Submission
Slide 196
Martial Belec, France Telecom
January 2006
doc.: IEEE 802.22-06/0009r0
US Contention-Based Coexistence with LE Devices
(Call Flow)
Primary BS
CPE
Normal data transmitting
Detect LE devices
Contention needed
Contend with LE at the next TXOP
Data transmitting in contention manner
Submission
Slide 197
Martial Belec, France Telecom