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Transcript of Doc.: IEEE 802.22-05/0105r1 Submission November 2005 Carlos Cordeiro, PhilipsSlide 1 A Cognitive...
November 2005
Carlos Cordeiro, Philips
Slide 1
doc.: IEEE 802.22-05/0105r1
Submission
A Cognitive PHY/MAC Proposal for IEEE 802.22 WRAN Systems
IEEE P802.22 Wireless RANs Date: 2005-11-07Authors:
Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.22.
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at [email protected].
Name Company Address Phone email
Carlos Cordeiro Philips 345 Scarborough Rd Briarcliff Manor, NY 10510 1-914-945-6091 [email protected]
Kiran Challapali Philips 345 Scarborough Rd Briarcliff Manor, NY 10510 1-914-945-6356 [email protected]
Dagnachew Birru Philips 345 Scarborough Rd Briarcliff Manor, NY 10510 1-914-945-6401 [email protected]
Vasanth Gaddam Philips 345 Scarborough Rd Briarcliff Manor, NY 10510 1-914-945-6424 [email protected]
Gene Turkenich Philips 345 Scarborough Rd Briarcliff Manor, NY 10510 1-914-945-6370 [email protected]
Martial Bellec France Telecom 4 rue du Clos Courtel 35512 Cesson-Sévigné - France 33 2 99 12 48 06 [email protected] Patrick Pirat France Telecom 4 rue du Clos Courtel 35512 Cesson-Sévigné - France 33 2 99 12 48 06 [email protected] Luis Escobar France Telecom 38-40 rue du Général Leclerc 92794 ISSY LES
MOULINEAUX France 33 245 29 46 22 [email protected]
Denis Callonnec France Telecom 28 Chemin du Vieux Chêne 38243 MEYLAN - France 33 4 76 76 44 12 [email protected] François Marx France Telecom 28 Chemin du Vieux Chêne 38243 MEYLAN - France 33 4 76 76 41 09 [email protected]
November 2005
Carlos Cordeiro, Philips
Slide 2
doc.: IEEE 802.22-05/0105r1
Submission
PHY Abstract
Digital modulation systems presently make use of two basic modulation technologies: single carrier and multi-carrier. Their features are well-known since they have been deployed for several years around the world for broadcasting applications.
Wireless access applications differ from broadcasting since they require : flexibility on the downstream link : variable number of user, variable throughput
per user, variable level of protection, etc; multiple access on the upstream link.Single carrier modulation can tackle these objectives through time multiplexing
techniques. Multi-carrier modulation is however more flexible since it enables to control the signal in both time and frequency domains. This gives the opportunity to define two dimensional (time and frequency) slots and to map the services to be transmitted in both directions onto a subset of these slots.
Two types of multi-carrier modulation has been retained in IEEE 802.16 (WiMAX) standard: OFDM in the fixed MAN version and OFDMA in the mobile version.
In the continuity of IEEE 802.16, it is proposed here to consider OFDMA modulation for downstream and upstream links with two technological improvements:
• Spreading;• OQAM waveforming.To meet the tight link budget requirements of WRAN, duo binary turbo code is
proposed for service ranges up to 100 Km
November 2005
Carlos Cordeiro, Philips
Slide 3
doc.: IEEE 802.22-05/0105r1
Submission
MAC Abstract
We propose the Cognitive MAC (CMAC) layer to be used as the basis for the future IEEE 802.22 WRAN standard operating in the TV bands. The proposed CMAC is in some respects inspired by the IEEE 802.16 standard, but it provides major extensions, improvements and also simplifications in order to meet the 802.22 functional requirements. CMAC is based on a superframe architecture which is general enough to allow multiple wireless systems to coexist in addition to support the flexibility to group multiple vacant TV channels and hence achieve greater capacity. To coexist with incumbent services, CMAC is able to efficiently manage distributed incumbent measurement, control, and recovery procedures, while also providing the necessary spectrum management features. To coexist amongst 802.22 systems, CMAC is the first of its kind to implement a novel coexistence beacon protocol (CBP) that allows BSs with overlapping coverage areas to coordinate and efficiently share the radio spectrum, hence minimizing interference. The efficiency of CBP is further improved by a new scheme that dynamically synchronizes overlapping BSs. Additional characteristics of CMAC include the support of various traffic types with different QoS requirements, flexible bandwidth management, and a combination of access mechanisms.
November 2005
Carlos Cordeiro, Philips
Slide 4
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction– A Glimpse of IEEE 802.22
• The Cognitive PHY Proposal
• The Cognitive MAC Proposal
• Conclusions
November 2005
Carlos Cordeiro, Philips
Slide 5
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction– A Glimpse of IEEE 802.22
• The Cognitive PHY Proposal
• The Cognitive MAC Proposal
• Conclusions
November 2005
Carlos Cordeiro, Philips
Slide 6
doc.: IEEE 802.22-05/0105r1
Submission
November 2005
Carlos Cordeiro, Philips
Slide 7
doc.: IEEE 802.22-05/0105r1
Submission
PAN< 10 m
802.15.1 (Bluetooth) – 1 Mbps802.15.3 > 20 Mbps
802.15.3a (UWB) < 480 Mbps802.15.4 (Zigbee) < 250 kbps
LAN< 150 m
11 – 54 Mbps
802.11a/b/e/gHiperLAN/2
802.11n (proposed) > 100 Mbps
MAN< 5 km
802.16a/d/e - 70 MbpsLMDS - 38 Mbps
WAN< 15 km
802.20 (proposed)GSM, GPRS, CDMA, 2.5G, 3G – 10
kbps to 2.4 Mbps
RAN< 100 km
802.22 (proposed) - 18 to 24 Mbps
The IEEE 802.22
• From 18 Mbps to 24 Mbps
• Propagation delays in excess of 300 µs
• Operates in TV bands– 54 to 862 MHz
– 6 MHz, 7 MHz and 8 MHz channel bandwidth
November 2005
Carlos Cordeiro, Philips
Slide 8
doc.: IEEE 802.22-05/0105r1
Submission
Deployment Scenario
• Master/Slave relationship
• Entities– Base Station (BS)
– Consumer Premise Equipment (CPE)
• 4W CPE transmit power
BS
BS
CPE
CPECPE
CPE
CPE
CPECPE
33 - 100 Km
Backbone Network
BS
CPE
CPE
BS
CPE
CPE
CPE
November 2005
Carlos Cordeiro, Philips
Slide 9
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction– A Glimpse of IEEE 802.22
• The Cognitive PHY Proposal
• The Cognitive MAC Proposal
• Conclusions
November 2005
Carlos Cordeiro, Philips
Slide 10
doc.: IEEE 802.22-05/0105r1
Submission
PHY Presentation Outline
• Background
• Top-level description of modulation/coding
• Channel bonding
• Modulation Parameters
• Spreading OFDMA
• Sensing techniques
• OQAM/OFDMA
• Duo-binary CTC
November 2005
Carlos Cordeiro, Philips
Slide 11
doc.: IEEE 802.22-05/0105r1
Submission
802.22 requirements consideration
• Regional Area Network (up to 30Km)– Operate in vacant TV bands– Detect vacant TV bands
• Large delay spread and roundtrip time• Data rate: from 1.5 Mbps DS and ~300 Kbps US• Should not cause harmful interference to other devices
– -70dB OOB emission– detect and avoid
• Flexibility– Bandwidth, bit rate, TX power, access mechanism, etc
• Spectral efficiency • 4 watt transmission power
November 2005
Carlos Cordeiro, Philips
Slide 12
doc.: IEEE 802.22-05/0105r1
Submission
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
• Option of OQAM/OFDMA and turbo code
RandomizerModulation
(constellationmapping)
InterleaverFEC
November 2005
Carlos Cordeiro, Philips
Slide 13
doc.: IEEE 802.22-05/0105r1
Submission
Why OFDMA ? • Single carrier and multi-carrier have been used for broadcasting, wireless
access, etc– Their behavior is well understood (capacity, filtering requirements, PAPR,
equalization, flexibility, efficiency)
• 802.22 Wireless access differ from broadcasting and most other system– flexibility in downstream and upstream link– variable # of users, variable throughput, – large round-trip signal delay– multiple access
• Multi-carrier system more suitable to meet these objectives– It enables to control the signal in time and frequency– Results in a two dimensional grid to assign resources to a user OFDMA– Resources can be allocated on a per user basis
• OFDM used in standards such as – WiMedia UWB, WiMAX (Fixed MAN), DAB, DMB, DVB-T, DVB-H, ISDB-T
• OFDMA used in WiMax, DVB-RCT
November 2005
Carlos Cordeiro, Philips
Slide 14
doc.: IEEE 802.22-05/0105r1
Submission
OFDMA
• Based on OFDMA (sub-channels per user)– US/DS
– Reduces overhead for short messages
– Flexibility in choosing modulation/coding for CPE
– Reduced PAPR for CPEs
frequency
Sub chan. 1 Sub chan. 2 Sub chan. 3 Sub chan. 4
November 2005
Carlos Cordeiro, Philips
Slide 15
doc.: IEEE 802.22-05/0105r1
Submission
Coding
PuncturerRate - ½
convolutionalcoder
PuncturerDuo-binary
CTC
CTC mode
CC mode
November 2005
Carlos Cordeiro, Philips
Slide 16
doc.: IEEE 802.22-05/0105r1
Submission
Modulation
S/PConstelation
mappingIFFT S/P
AddGI
OFDMA
OQAM/OFDMA
1:NReal QAMmodulator
OFDM/IOTA symbol rate =N/0 symbols/sec
N symbolstreams1/0symbol/sec
IFFT
OFDM/IOTAsymbols1/0symbol/sec
N/2 :1 OFDM/IOTAsymbols
IOTAPolyphaseFiltering
November 2005
Carlos Cordeiro, Philips
Slide 17
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 18
doc.: IEEE 802.22-05/0105r1
Submission
Channel Bonding/capacity
• Aggregate TV channels to get more capacity– Shannon: C = B.log2(1+S/N)
– Capacity proportional to BW, but logarithmic with SNR or signal power
• If S/N is fixed, then capacity increases linearly with bandwidth
• If signal power is fixed, but bandwidth is increased– C = B.log2(1+S/(BNo))
– Capacity still increases as bandwidth is increased
November 2005
Carlos Cordeiro, Philips
Slide 19
doc.: IEEE 802.22-05/0105r1
Submission
Capacity of aggregated channels as a given signal power is spread over more channels
November 2005
Carlos Cordeiro, Philips
Slide 20
doc.: IEEE 802.22-05/0105r1
Submission
Channel bonding
• 6, 12, 18 MHz channels
• Depends on availability
• Several receiver techniques to deal with flexible BW– Selectable analog filters
– Up sampling digital filters
TVTV
WRAN
N N+1 N+2N-1N-2 N+4N+3N-3
TVTV
WRAN
N N+1 N+2N-1N-2 N+4N+3N-3
TVTV
WAN
N N+1 N+2N-1N-2 N+4N+3N-3
November 2005
Carlos Cordeiro, Philips
Slide 21
doc.: IEEE 802.22-05/0105r1
Submission
Channel bonding structure
• 6K FFT over 3 TV channels– 2K per TV channel
– Null out the outer carriers for 1 or 2 TV channels
• Fixed inter-carrier spacing– Several implementation
possibilities
DataSub-carrier
PilotSub-carrier
Guard/NullSub-carrier
6 MHz
18 MHz
12 MHz
DC
DC
DC
12 MHz
6 MHz
18 MHz
November 2005
Carlos Cordeiro, Philips
Slide 22
doc.: IEEE 802.22-05/0105r1
Submission
Frame structure: Superframe
Superframe n-1 Superframe n Superframe n+1 ...Time
...
Preamble SCH frame 0 frame 1 frame m...
TV Channelt-1
TV Channelt
TV Channelt+1
Time
Preamble SCH
Preamble SCH
Fre
qu
en
cy
Preamble SCHFrame
0Frame
1
Framem-2
(Quiet)...
... Frame0
Frame1
Preamble SCH
Preamble SCH
Occupied by Incumbent
Occupied by Incumbent
Framen
Occupied by Incumbent
Framem
Framem-1
November 2005
Carlos Cordeiro, Philips
Slide 23
doc.: IEEE 802.22-05/0105r1
Submission
Spectrum of the signal (before further filtering)
Produced using a 6K FFT
for a single TV channel
November 2005
Carlos Cordeiro, Philips
Slide 25
doc.: IEEE 802.22-05/0105r1
Submission
Inter-carrier spacing and FFT/IFFT period values for different bandwidth options
Table 2: Inter-carrier spacing and FFT/IFFT period values for different bandwidth options
6 MHz based channels
(6, 12 and 18 MHz)
7 MHz based channels
(7, 14 and 21 MHz)
8 MHz based channels
(8, 16 and 24 MHz)
Inter-carrier spacing, F (Hz)
3348.214 3906.625 4464.286
FFT/IFFT period, TFFT (s)
298.666 256.000 224.000
November 2005
Carlos Cordeiro, Philips
Slide 26
doc.: IEEE 802.22-05/0105r1
Submission
OFDMA parameters
3 TV bands 2 TV bands 1 TV band Parameter
18 21 24 12 14 16 6 7 8 Inter-carrier spacing,
F (Hz) 3348 3906 4464 3348 3906 4464 3348 3906 4464
FFT period, TFFT (s) 298.66 256.00 224.00 298.66 256.00 224.00 298.66 256.00 224.00
Total no. of sub-carriers,
NFFT 6144 4096 2048
No. of guard sub-carriers,
NG (L, DC, R) 960 (480, 1, 479) 640 (320, 1, 319) 320 (160, 1, 159)
No. of used sub-carriers,
NT = ND+ NP 5184 3456 1728
No. of data sub-carriers,
ND 4608 3072 1536
No. of pilot sub-carriers, NP 576 384 192
Signal bandwidth (MHz)
17.356 20.249 23.141 11.571 13.500 15.428 5.785 6.750 7.714
November 2005
Carlos Cordeiro, Philips
Slide 27
doc.: IEEE 802.22-05/0105r1
Submission
Modulation/coding modes and corresponding rates
PHY Mode Modulation Coding Rate Spreading
Factor Spreading Matrix
Data rate (Mb/s)
0 QPSK ½ 4 SCH 1 QPSK ½ 1 Hadamard 4.84 2 QPSK ½ 1 Identity 4.84 3 QPSK ¾ 1 Hadamard 7.26 4 QPSK ¾ 1 Identity 7.26 5 16-QAM ½ 1 Identity 9.68 6 16-QAM ¾ 1 Identity 14.52 7 64-QAM ½ 1 Identity 14.52 8 64-QAM 2/3 1 Identity 19.36 9 64-QAM ¾ 1 Identity 21.78
10 64-QAM 5/6 1 Identity 24.20 11 OQPSK ½ tbd tbd 5.14 12 OQPSK 2/3 tbd tbd 6.86 13 OQPSK ¾ tbd tbd 7.71 14 16-OQAM ½ tbd tbd 10.29 15 16-OQAM 2/3 tbd tbd 13.71 16 16-OQAM 3/4 tbd tbd 15.43 17 64-OQAM ½ tbd tbd 15.43 18 64-OQAM 2/3 tbd tbd 20.57
November 2005
Carlos Cordeiro, Philips
Slide 28
doc.: IEEE 802.22-05/0105r1
Submission
Preamble
• Superframe preamble – Over 1512 sub-carriers (every fourth or second non-zero),
– 5 MHz BW
– Simply duplicate for additional TV channels
– 1 MHz gap between adjacent channels to relax filtering
– 2 symbol duration (1 more for data)
• Frame preamble: 1-3 TV channels – 1728*N sub-carriers
– Short preamble is optional
ST1 ST5ST4ST3ST2 LT1 LT2GI
TSYMTSYM (short) (long)
November 2005
Carlos Cordeiro, Philips
Slide 29
doc.: IEEE 802.22-05/0105r1
Submission
Spreaded QPSK/OFDMA
• Spread data over some sub-carriers (Hadamard)
• Increases capturing of multipath diversity
• Increases resiliency to interferers
• Simple receiver structure (MMSE)
dev 1(64QAM)
dev3
dev5 (16QAM)
Dev4 (S-QPSK)
Dev2 (16QAM)
Dev7 (S-QPSK)dev6 (64QAM)
Dev8(64QAM)
1234
Time (in OFDM symbol unit)
subchannels
HxY
November 2005
Carlos Cordeiro, Philips
Slide 30
doc.: IEEE 802.22-05/0105r1
Submission
Simulation results for QPSK, rate 3/4
S-OFDMA gives 2-4dB
gain!
Channels: •ATSC Brazil D•802.22 Profile A •All with Doppler
November 2005
Carlos Cordeiro, Philips
Slide 31
doc.: IEEE 802.22-05/0105r1
Submission
Preliminary Link Budget(LOS)Throughput/channel 5 19 Mb/scenter frequency 0.7 0.7 GHzbandwidth 6 6 MHzDistance 30000 30000 mTx power 4 4 WTx averg power 36.0 36.0 dBmTX antenna gain 18.0 18.0 dBiRx powerfree space path loss 119 119 dBRx antenna gain 12 12 dBicable and other losses 3 3 dBTotal received avrg power -56 -56 dBmReceiver noise figure 4 4 dBNoise power -106 -106 dBmInterference allowance 3 3 dBReceived SNR 43 43 dBRequired SNR 4 25 dBImplementation/OFDM loss 6.0 6.0 dBLink Margin 33.4 12.4 dB
November 2005
Carlos Cordeiro, Philips
Slide 32
doc.: IEEE 802.22-05/0105r1
Submission
Other Features
• Ranging
• Transmitter Power Control (TPC)
• Consideration of multiple antenna
November 2005
Carlos Cordeiro, Philips
Slide 33
doc.: IEEE 802.22-05/0105r1
Submission
Channel Measurement
• Received signal strength– Quality measurement of its own signal (TPC, modulation/coding)
– Fast channel ‘busy’ detection
• Signal feature detection– Detection of the type of the signal
• ATSC, DVB-T, Part 74, .22, etc
– Should be robust to receiver imperfections
November 2005
Carlos Cordeiro, Philips
Slide 34
doc.: IEEE 802.22-05/0105r1
Submission
Received Signal Strength
• Several implementation techniques– FFT, IOTA/FFT, simple low-pass filter etc
– Possibility to measure a part of the spectrum
• Various degrees of performance
• Integration time and threshold is very important
• BS sets essential parameters (constant)
• Either the BS makes the detection decision based on the collective measurement results or CPE’s can make the decision – distributed measurement
November 2005
Carlos Cordeiro, Philips
Slide 35
doc.: IEEE 802.22-05/0105r1
Submission
Simulated performances of OFDM and OQAM: detecting ATSC pilot
5ms integration time
November 2005
Carlos Cordeiro, Philips
Slide 36
doc.: IEEE 802.22-05/0105r1
Submission
DTV signal feature detection
• 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
November 2005
Carlos Cordeiro, Philips
Slide 37
doc.: IEEE 802.22-05/0105r1
Submission
MULTIPATH SIMULATOR
ATTENUATOR
RECEIVER
8VSB_SOURCE
Experimental setup for DTV detection
November 2005
Carlos Cordeiro, Philips
Slide 40
doc.: IEEE 802.22-05/0105r1
Submission
ENERGY SENSOR, DETECTION RATE, %
VSB SENSOR, DETECTION RATE, %
PATH 1 POWER, dBm PATH 1 POWER, dBm
DELAY, usec
DOPPLER, Hz
ATTEN, dB
-107 -100 -90 -107 -100 -90 PATH 1 0 0 0
PATH 2 3.0 0.1 7.0
PATH 3 8.0 2.5 15.0 100 100 100 100 100 100 PATH 4 11.0 0.13 22.0
PATH 5 13.0 0.17 24.0
PATH 6 21.0 0.37 19.0
Based on Doc.: IEEE802.22-05/0055r7.
Profile A.
November 2005
Carlos Cordeiro, Philips
Slide 42
doc.: IEEE 802.22-05/0105r1
Submission
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 be
employed to better localize the spectrum)• Perform FFT • Average each freq bin
• Average across freq bin
– Compute mean and “variance”
1
0
2),(
1),(
K
i
mikYK
mkP
1
0
1
0
),(
),(
N
mkk
N
mk
mkP
mkP
FFT
avg
W.F.
V>k*avg
November 2005
Carlos Cordeiro, Philips
Slide 43
doc.: IEEE 802.22-05/0105r1
Submission
Part 74 detection (cont.)
• Detection
• Theoretical performance
N
M
M
KKalarmfalseob
KKectionob
KKmissob
),(1.__Pr
),(1det_Pr
),(_Pr
kk kkmkP 21)),(max(
November 2005
Carlos Cordeiro, Philips
Slide 44
doc.: IEEE 802.22-05/0105r1
Submission
Narrow-band detection (Part 74): Theoretical and simulated performance
November 2005
Carlos Cordeiro, Philips
Slide 45
doc.: IEEE 802.22-05/0105r1
Submission
Probability of miss detection and false alarm
November 2005
Carlos Cordeiro, Philips
Slide 46
doc.: IEEE 802.22-05/0105r1
Submission
Detector Link Margin
center frequency 0.7 0.7 GHzbandwidth 200 200 KHzDistance 500 1500 mTx power 10 10 mWTx averg power 10.0 10.0 dBmTX antenna gain 0.0 0.0 dBiRx powerfree space path loss 83 93 dBRx antenna gain 0 0 dBicable and other losses 3 3 dBTotal received avrg power -76 -86 dBmReceiver noise figure 4 4 dBNoise power -121 -121 dBmInterference allowance 3 3 dBFading allowance 10 20 dBBody absorption 10 10 dBReceived SNR 18 -2 dB
Required SNR -6 -6 dBImplementation loss 3.0 3.0 dBLink Margin 20.7 1.1 dB
November 2005
Carlos Cordeiro, Philips
Slide 47
doc.: IEEE 802.22-05/0105r1
Submission
PHY Presentation Outline
• Background
• Top-level description of modulation/coding
• Channel bonding
• Modulation Parameters
• Spreading OFDMA
• Sensing techniques
• OQAM/OFDMA
• Duo-binary CTC
November 2005
Carlos Cordeiro, Philips
doc.: IEEE 802.22-05/0105r1
Submission
OFDM/OQAM Outline
• Principles of OFDM/OQAM
• The IOTA Waveform
• Advantages of OFDM/OQAM
• Simulation results
November 2005
Carlos Cordeiro, Philips
doc.: IEEE 802.22-05/0105r1
Submission
OFDM/OQAM principles (1)
• Aim: to increase OFDM spectral efficiency by :– Removing the guard interval (cyclic prefix);
– Delivering a sharper spectral signal than OFDM.
• How: The waveform that modulates OFDM sub-carriers should be as much as possible localized in time and frequency domains to minimize inter-symbol and inter-carrier interferences.
November 2005
Carlos Cordeiro, Philips
doc.: IEEE 802.22-05/0105r1
Submission
OFDM/OQAM principles (2)
• However, the waveform must guarantee orthogonality between sub-carriers and multi-carrier symbols.– Appropriate waveform exist but guarantee orthogonality in the real
domain OffsetQAM modulation should be considered on each sub-carrier.
• Example: IOTA waveform (optimally localized in time and frequency).
November 2005
Carlos Cordeiro, Philips
doc.: IEEE 802.22-05/0105r1
Submission
OFDM/OQAM principles (3)
• OFDM/QAMTransmitted signal:
• takes the complex value representing the transmitted encoded data sent on the mth sub-carrier at the nth symbol;
• and the basic functions are obtained by translation in time and frequency of a prototype function such as:
• With• Rectangular function x used in OFDM has weak frequency
localization.
• OFDM/OQAM• Introduces a time offset between real and imaginary parts of
symbols• takes real values;• And with
nm
nm txts,
,nm,a)(
nma ,
tx nm,
02
,0 ntxetx tmi
nm 100
nma ,
02
,0 ntxeitx tminm
nm 2/100
November 2005
Carlos Cordeiro, Philips
Slide 52
doc.: IEEE 802.22-05/0105r1
Submission
OFDM/OQAM principles (3)
• Time-frequency lattice
November 2005
Carlos Cordeiro, Philips
doc.: IEEE 802.22-05/0105r1
Submission
The IOTA function (1)
IOTA = Isotropic Orthogonal Transform Algorithm
• IOTA is a prototype function obtained by the orthogonalization of the Gaussian function
• Its particularity: the IOTA waveform modulating each sub-carrier is:
– Quasi-optimally localized in both time and frequency
– Isotropic: it has the same shape as its Fourier transform => delay spread and Doppler are both equally managed
November 2005
Carlos Cordeiro, Philips
doc.: IEEE 802.22-05/0105r1
Submission
The IOTA function (2)
0 0 2*0 30
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
symbol duration
Am
plit
ude
IOTA
-2*0 0- 30
0 0 2*0 30
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Inter-carrier spacing
Am
plitu
de
IOTA Fourier Transform
-2*0 0- 30
November 2005
Carlos Cordeiro, Philips
doc.: IEEE 802.22-05/0105r1
Submission
The IOTA function (3)
• The IOTA function can be denoted by:
Where:
• The transmitted signal is:
22
,, ntIeetI mtii
nmnm
2/)(, nmnm
2
2,
, ntIeeats mtiinm
nm
November 2005
Carlos Cordeiro, Philips
Slide 56
doc.: IEEE 802.22-05/0105r1
Submission
Advantages of OFDM/OQAM (1)• Spectrum is sharper : 70 dB instead of 30 dB
• This feature helps to protect the adjacent channels
November 2005
Carlos Cordeiro, Philips
Slide 57
doc.: IEEE 802.22-05/0105r1
Submission
Advantage of OFDM/OQAM (2)
• Cyclic prefix not mandatory more useful bit-rate
• This extra bit-rate may be used to:–Increase the global net bit-rate of the system;
–Increase the robustness and therefore the range, or decrease the power.
Cyclic prefix 1/4 1/8 1/16 1/32
Bit-rate OFDM/QAM 1/2 11.57 Mbits/s 13.5 Mbits/s 14.47 Mbits/s 14.95 Mbits/s
Bit-rate OFDM/OQAM 1/2 15.43 Mbits/s 15.43 Mbits/s 15.43 Mbits/s 15.43 Mbits/s
November 2005
Carlos Cordeiro, Philips
Slide 58
doc.: IEEE 802.22-05/0105r1
Submission
Simulation resultsSimulation parameters:
– Constellation : 64 QAM
– Coding rate : ½
– Bandwidth : 7 MHZ
– Channel: 641 MHz
– Channel model: Profile A of WRANProfile A
-30
-25
-20
-15
-10
-5
0
-10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Excess delay (usec)
Re
lati
ve
att
en
ua
tio
n (
dB
)
November 2005
Carlos Cordeiro, Philips
Slide 59
doc.: IEEE 802.22-05/0105r1
Submission
OFDM/OQAM vs OFDM/QAMwith Convolutional FEC
Convolutional rate 1/2
-6
-5
-4
-3
-2
-1
0
13 14 15 16 17 18 19 20 21
C/N
BE
R (
log
)
OFDM
OQAM
November 2005
Carlos Cordeiro, Philips
Slide 60
doc.: IEEE 802.22-05/0105r1
Submission
OFDM/OQAM vs OFDM/QAMwith Duo-binary Turbo-codes
Duo-binary Turbo-code rate 1/2
-6
-5
-4
-3
-2
-1
0
13 14 15 16 17 18 19 20 21
C/N
BE
R (
log
)
OFDM
OQAM
November 2005
Carlos Cordeiro, Philips
Slide 61
doc.: IEEE 802.22-05/0105r1
Submission
State of the art
• OQAM waveform has been standardized by TIA committee TR8 for Private Land Mobile applications
November 2005
Carlos Cordeiro, Philips
Slide 62
doc.: IEEE 802.22-05/0105r1
Submission
PHY Presentation Outline
• Background
• Top-level description of modulation/coding
• Channel bonding
• Modulation Parameters
• Spreading OFDMA
• Sensing techniques
• OQAM/OFDMA
• Duo-binary CTC
November 2005
Carlos Cordeiro, Philips
Slide 63
doc.: IEEE 802.22-05/0105r1
Submission
Duo-binary Turbo-codes Outline
• Duo-Binary Turbo Codes
• Internal interleaver
• Flexibility
• Performance
• Simulations
November 2005
Carlos Cordeiro, Philips
Slide 64
doc.: IEEE 802.22-05/0105r1
Submission
Duo-Binary Turbo-codes
Information bits are encoded by
couples
November 2005
Carlos Cordeiro, Philips
Slide 65
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 66
doc.: IEEE 802.22-05/0105r1
Submission
Internal Interleaver
• Algorithmic permutation–One equation, 4 parameters (P0, P1, P2, P3)
–Parameters selected such that interleaver is contention-free
• Adjusting the TC to a blocksize only requires modification of the 4 parameters
• Quasi-regular permutation (easy connectivity)
• Inherent parallelism
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:
- 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
November 2005
Carlos Cordeiro, Philips
Slide 67
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 68
doc.: IEEE 802.22-05/0105r1
Submission
Flexibility
• The number of iterations can be adjusted for a better performance-complexity trade-off
November 2005
Carlos Cordeiro, Philips
Slide 69
doc.: IEEE 802.22-05/0105r1
Submission
Performance
• Duo-Binary TC, 8 iterations, Max-Log-MAP decoding
• IEEE 802.16e structured LDPC, BP decoding, 50 iterations
• AWGN, R=1/2, QPSK
• N=576 and 2304 (coded blocksize)
November 2005
Carlos Cordeiro, Philips
Slide 70
doc.: IEEE 802.22-05/0105r1
Submission
Short blocksize performance
• Hardware measurements
• Low BER (down to 10-11) are achievable without error floor
November 2005
Carlos Cordeiro, Philips
Slide 71
doc.: IEEE 802.22-05/0105r1
Submission
Simulation results• Simulation parameters
– Constellation : 64 QAM
– Coding rate : ½
– Bandwidth : 7 MHZ
– Channel: 641 MHz
– Channel model: Profile A of WRANProfile A
-30
-25
-20
-15
-10
-5
0
-10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Excess delay (usec)
Re
lati
ve
att
en
ua
tio
n (
dB
)
November 2005
Carlos Cordeiro, Philips
Slide 72
doc.: IEEE 802.22-05/0105r1
Submission
Duo-binary Turbo-codes vs Convolutionalwith OFDM/QAM modulation
OFDM 64 QAM rate 1/2
-6
-5
-4
-3
-2
-1
0
13 14 15 16 17 18 19 20 21
C/N
BE
R (
log
)
Convolutional
DTC
November 2005
Carlos Cordeiro, Philips
Slide 73
doc.: IEEE 802.22-05/0105r1
Submission
Duo-binary Turbo-codes vs Convolutionalwith OFDM/OQAM modulation
OQAM 64 QAM rate 1/2
-6
-5
-4
-3
-2
-1
0
13 14 15 16 17 18 19 20 21
C/N
BE
R (
log
)
Convolutional
DTC
November 2005
Carlos Cordeiro, Philips
Slide 74
doc.: IEEE 802.22-05/0105r1
Submission
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.
November 2005
Carlos Cordeiro, Philips
Slide 75
doc.: IEEE 802.22-05/0105r1
Submission
State of the art
• Duo-binary Turbo-code is a mature technology
• This technology has already been selected by several standardization groups– IEEE 802.16 / WiMAX;
– DVB-RCS;
– DVB-RCT;
– ETSI HIPERMAN
November 2005
Carlos Cordeiro, Philips
Slide 76
doc.: IEEE 802.22-05/0105r1
Submission
Summary:Gains brought by OQAM and DTC
• OFDM/OQAM brings 10% more bit-rate– When converted in error protection enables to go from ¾ rate to
2/3
– Gain between 1 and 1,5 dB in C/N
• 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.
November 2005
Carlos Cordeiro, Philips
Slide 77
doc.: IEEE 802.22-05/0105r1
Submission
Final conclusion for WRAN PHY
• OFDMA/Channel bonding– Good answer to flexibility requirements
• Spreading QPSK– Captures multipath diversity and increases resiliency to
interference (2-4 dB gain)
• OQAM waveform– Increases efficiency and incumbent protection
• Duo-binary Turbo-codes– Powerful error protection technique
November 2005
Carlos Cordeiro, Philips
Slide 78
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction– A Glimpse of IEEE 802.22
• The Cognitive PHY Proposal
• The Cognitive MAC Proposal
• Conclusions
November 2005
Carlos Cordeiro, Philips
Slide 79
doc.: IEEE 802.22-05/0105r1
Submission
CMAC Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 80
doc.: IEEE 802.22-05/0105r1
Submission
CMAC Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 81
doc.: IEEE 802.22-05/0105r1
Submission
Introduction
• A Cognitive MAC (CMAC) layer is proposed to be used as the future IEEE 802.22 MAC for WRANs
• Some aspects of CMAC 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);
• Measurements (incumbents and itself)• Spectrum management (time, frequency and power)• The Coexistence Beacon Protocol (CBP)• Synchronization of overlapping BSs• The Incumbent Detection Recovery Protocol (IDRP)• Embedded wireless microphone beacon mechanism
– Clustering support; etc.
November 2005
Carlos Cordeiro, Philips
Slide 82
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 83
doc.: IEEE 802.22-05/0105r1
Submission
Overview
• Given the very long propagation delays in WRANs, the BS regulates the medium access– Downstream: TDM
(Time Division Multiplexing)
– Upstream: DAMA (Demand Assigned Multiple Access) TDMA
Packet Size: 50 bytes Packet Size: 1500 bytes
November 2005
Carlos Cordeiro, Philips
Slide 84
doc.: IEEE 802.22-05/0105r1
Submission
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)
November 2005
Carlos Cordeiro, Philips
Slide 85
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 86
doc.: IEEE 802.22-05/0105r1
Submission
Protocol Stack Architecture
• Flexibility, scalability and efficiency are core elements
• Spectrum manager could be implemented in many ways
Convergence Sublayer / Bridge (e.g., 802.1d)
MAC
PHY
...MAC
PHY
MAC
PHY
Spectrum Manager
Higher Layers: IP, ATM, 1394, etc.
PHY/MAC 1 PHY/MAC 2 PHY/MAC n
November 2005
Carlos Cordeiro, Philips
Slide 87
doc.: IEEE 802.22-05/0105r1
Submission
Protocol Stack Architecture (cont.)
• Flexible channel assignment– Implementers decide on the algorithm
Used by incumbents (e.g., TV stations)
54321 6 7
Vacant and available for use by 802.22
Allo
cate
dto
PH
Y/M
AC 1
Use
d b
y ano
ther
80
2.2
2 c
ell
Use
d b
y an
oth
er
802.2
2 c
ell
Frequency
Allo
cate
dto
PH
Y/M
AC 2
November 2005
Carlos Cordeiro, Philips
Slide 88
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 89
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 90
doc.: IEEE 802.22-05/0105r1
Submission
Motivation
• The problem– How to offer enhanced capacity and higher data rates?
• 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
November 2005
Carlos Cordeiro, Philips
Slide 91
doc.: IEEE 802.22-05/0105r1
Submission
Superframe n-1 Superframe n Superframe n+1 ...Time
...
Preamble SCH frame 0 frame 1 frame m...
TV Channelt-1
TV Channelt
TV Channelt+1
Time
Preamble SCH
Preamble SCH
Fre
qu
en
cy
Preamble SCHFrame
0Frame
1
Framem-2
(Quiet)...
... Frame0
Frame1
Preamble SCH
Preamble SCH
Occupied by Incumbent
Occupied by Incumbent
Framen
Occupied by Incumbent
Framem
Framem-1
Superframe Structure
Superframe Control Header (SCH)
• TV channels being bonded• Coexistence and superframe information
• Number and size of frames• Information on periodic quiet periods• ID an transmit power of transmitter
•Location configuration information
November 2005
Carlos Cordeiro, Philips
Slide 92
doc.: IEEE 802.22-05/0105r1
Submission
Frame Structure
• CMAC is based on a TDD frame structure– Reduced complexity
– In general, less measurements overhead
– The flexible architecture (with the Spectrum Manager) already brings with it aspects of FDD
• The CMAC frame structure is comprised of two parts– A predominantly downstream (DS) subframe
– An upstream (US) subframe
November 2005
Carlos Cordeiro, Philips
Slide 93
doc.: IEEE 802.22-05/0105r1
Submission
Frame Structure (cont.)
frame n-1 frame n frame n+1 ...Time
...
DS PHY PDU
Preamble FCH DS burst 1 DS burst 2 DS burst x...
BcastMsgs
MACPDUs
MAC PDU 1 ... MAC PDU y Pad
MACHeader
MAC Payload CRC
DS subframe
Initializationslots
BW requestslots
US PHY PDU(CPE m)
US PHY PDU(CPE p)
...
US subframe
Preamble US burst
MAC PDU 1 ... MAC PDU k Pad
MACHeader
MAC Payload CRC
Sliding self-coexistence
slots
Can appear ineither DS or US
BCH
UCSNotification
Slots
November 2005
Carlos Cordeiro, Philips
Slide 94
doc.: IEEE 802.22-05/0105r1
Submission
Time/Frequency Structure of a MAC Frame
frame n-1 frame n frame n+1 ...Time
...
MAC Slot Number
Pre
am
ble
FCH
DS
-MA
PU
S-M
AP
Self-
coexi
stence
Ranging
UCS Notification
Burst CPE #4
Burst CPE #2
Burst CPE #1
Burst CPE #5
Burst CPE #3
Burst CPE #7
Burst CPE #1
Burst CPE #2
Burst CPE #4
Burst CPE #5
Burst CPE #3
Burst CPE #6
Burst CPE #8
Burst CPE #9
Self-
coexi
stence
Burst CPE #6
Burst CPE #7
Burst CPE #8
TTG
k k+1 k+3 k+5 k+7 k+9 k+11 k+13 k+15 k+17 k+20 k+23 k+26 k+29
TV Channel N
TV Channel N+1
DS US
Log
ica
l MA
C C
hannel N
um
ber
s
s+1
s+2
s+L
BW Request
November 2005
Carlos Cordeiro, Philips
Slide 95
doc.: IEEE 802.22-05/0105r1
Submission
Network Entry and Initialization
BS onchannel #52
CPE 3
CPE 1
CPE 2
Radio range of802.22 BS
• The key problem
CPE 4
TVstation onchannel
#52
Grade B contourof TV station
Radio range ofTV station
November 2005
Carlos Cordeiro, Philips
Slide 96
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 97
doc.: IEEE 802.22-05/0105r1
Submission
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)
November 2005
Carlos Cordeiro, Philips
Slide 98
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 99
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 100
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 101
doc.: IEEE 802.22-05/0105r1
Submission
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)
November 2005
Carlos Cordeiro, Philips
Slide 102
doc.: IEEE 802.22-05/0105r1
Submission
Measurements
• Measurements form a key component of CMAC– 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
November 2005
Carlos Cordeiro, Philips
Slide 103
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 104
doc.: IEEE 802.22-05/0105r1
Submission
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
1 n2 . ..Time
n measurementrepetitions
Duration Restart Delay RandomizationInterval
November 2005
Carlos Cordeiro, Philips
Slide 105
doc.: IEEE 802.22-05/0105r1
Submission
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)
November 2005
Carlos Cordeiro, Philips
Slide 106
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 107
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 108
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 109
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 110
doc.: IEEE 802.22-05/0105r1
Submission
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 Study/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
November 2005
Carlos Cordeiro, Philips
Slide 111
doc.: IEEE 802.22-05/0105r1
Submission
Incumbent Notification
• The problem– How to notify the BS about the presence of incumbents in a timely
fashion?
• Two solutions are possible– CPEs with upstream bandwidth allocation
• Send report provided bandwidth and time are available; and/or• 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
November 2005
Carlos Cordeiro, Philips
Slide 112
doc.: IEEE 802.22-05/0105r1
Submission
Incumbent Notification (cont.)
frame n-1 frame n frame n+1 ...Time
...
MAC Slot Number
Pre
am
ble
FCH
DS
-MA
PU
S-M
AP
Self-
coexi
stence
Ranging
UCS Notification
Burst CPE #4
Burst CPE #2
Burst CPE #1
Burst CPE #5
Burst CPE #3
Burst CPE #7
Burst CPE #1
Burst CPE #2
Burst CPE #4
Burst CPE #5
Burst CPE #3
Burst CPE #6
Burst CPE #8
Burst CPE #9
Self-
coexi
stence
Burst CPE #6
Burst CPE #7
Burst CPE #8
TTG
k k+1 k+3 k+5 k+7 k+9 k+11 k+13 k+15 k+17 k+20 k+23 k+26 k+29
TV Channel N
TV Channel N+1
DS US
Log
ica
l MA
C C
hannel N
um
ber
s
s+1
s+2
s+L
BW Request
RTG
November 2005
Carlos Cordeiro, Philips
Slide 113
doc.: IEEE 802.22-05/0105r1
Submission
Incumbent Notification (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
1 n2 . ..Time
n QuietPeriods
Duration
Quiet PeriodNotification Phase
Normal System OperationNotification Phase
November 2005
Carlos Cordeiro, Philips
Slide 114
doc.: IEEE 802.22-05/0105r1
Submission
Incumbent Detection Recovery
• The problem– How does the 802.22 cell recover from an UCS with incumbents
in a timely fashion?
November 2005
Carlos Cordeiro, Philips
Slide 115
doc.: IEEE 802.22-05/0105r1
Submission
Incumbent Detection Recovery (cont.)
• The Incumbent Detection Recovery Protocol (IDRP)– Introduces the concept of Backup Channel
– The 802.22 network not only performs in-band measurements, but also out-of-band measurements• Out-of-band measurements will determine a suitable Backup Channel
– The 802.22 network falls back to the 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 Backup Channel
is available
November 2005
Carlos Cordeiro, Philips
Slide 116
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 117
doc.: IEEE 802.22-05/0105r1
Submission
Self-Coexistence
• The general problem
TDMA Schedule
November 2005
Carlos Cordeiro, Philips
Slide 118
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 119
doc.: IEEE 802.22-05/0105r1
Submission
Self-Coexistence (cont.)
• Some approaches to better self-coexistence– Over the backhaul
• 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)
November 2005
Carlos Cordeiro, Philips
Slide 120
doc.: IEEE 802.22-05/0105r1
Submission
Self-Coexistence (cont.)
• Two solutions are proposed– BS beacon based– The Coexistence Beacon Protocol (CBP)
• 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
November 2005
Carlos Cordeiro, Philips
Slide 121
doc.: IEEE 802.22-05/0105r1
Submission
Self-Coexistence (cont.)
• BS beacon based– Implemented through
overheard BS beacons
– BS beacons carry various information:
• Channels used
• Quiet periods
• Frame information
• Transmit power level
– If needed, can use sensing antenna for this purpose
– Allows better TPC and sharing in frequency only
Case 1:
Case 2:
November 2005
Carlos Cordeiro, Philips
Slide 122
doc.: IEEE 802.22-05/0105r1
Submission
Self-Coexistence (cont.)
• Coexistence Beacon Protocol (CBP)
– CBP is executed by CPEs but under BS control
– CPEs transmit coexistence packets carrying two types of information
• About the cell
• About a CPE’s reservations with the BS
– Allows better TPC and sharing in both frequency and time
CBP beaconCBP beacon
November 2005
Carlos Cordeiro, Philips
Slide 123
doc.: IEEE 802.22-05/0105r1
Submission
Self-Coexistence (cont.)
frame n-1 frame n frame n+1 ...Time
...
MAC Slot Number
Pre
am
ble
FCH
DS
-MA
PU
S-M
AP
Self-
coexi
stence
Ranging
UCS Notification
Burst CPE #4
Burst CPE #2
Burst CPE #1
Burst CPE #5
Burst CPE #3
Burst CPE #7
Burst CPE #1
Burst CPE #2
Burst CPE #4
Burst CPE #5
Burst CPE #3
Burst CPE #6
Burst CPE #8
Burst CPE #9
Self-
coexi
stence
Burst CPE #6
Burst CPE #7
Burst CPE #8
TTG
k k+1 k+3 k+5 k+7 k+9 k+11 k+13 k+15 k+17 k+20 k+23 k+26 k+29
TV Channel N
TV Channel N+1
DS US
Log
ica
l MA
C C
hannel N
um
ber
s
s+1
s+2
s+L
BW Request
November 2005
Carlos Cordeiro, Philips
Slide 124
doc.: IEEE 802.22-05/0105r1
Submission
But what does the CPEs do with this information?
• If previously requested by the BS, report it
• 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
November 2005
Carlos Cordeiro, Philips
Slide 125
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 126
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 127
doc.: IEEE 802.22-05/0105r1
Submission
Synchronization of Overlapping BSs
• The problem– Frames of co-channel overlapping BSs are asynchronous, which makes
coexistence even harder
• 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
frame 0 frame 1 frame m...
frame 0 frame 1 frame m...
BS1:
BS2:
Time
November 2005
Carlos Cordeiro, Philips
Slide 128
doc.: IEEE 802.22-05/0105r1
Submission
Synchronization of Overlapping BSs (cont.)
• Synchronization is proposed amongst multiple collocated 802.22 networks
MAC Slot Number
Pre
am
ble
FCH
DS
-MA
PU
S-M
AP
Se
lf-co
exi
ste
nce
UCS Notification
Burst CPE #4
Burst CPE #2
Burst CPE #1
Burst CPE #5
Burst CPE #3
Burst CPE #1
Burst CPE #2
Burst CPE #4
Burst CPE #3
TTG
k k+1 k+3 k+5 k+7 k+9 k+11 k+13 k+15 k+17 k+20 k+23 k+26 k+29
Lo
gic
al M
AC
Ch
an
ne
l Nu
mb
er
s
s+1
s+2
s+L
BW Request
Frame n at BS1:
Frame m at BS2:
Pre
am
ble
FCH
DS
-MA
PU
S-M
AP
Se
lf-co
exi
ste
nce
UCS Notification
Burst CPE #4
Burst CPE #2
Burst CPE #1
Burst CPE #5
Burst CPE #3
Burst CPE #1
Burst CPE #2
Burst CPE #4
Burst CPE #3
TTG
Lo
gic
al M
AC
Ch
an
ne
l Nu
mb
er
s
s+1
s+2
s+L
BW Request
CBP packets
Time
November 2005
Carlos Cordeiro, Philips
Slide 129
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 130
doc.: IEEE 802.22-05/0105r1
Submission
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– 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
CPE
Cluster
BS
November 2005
Carlos Cordeiro, Philips
Slide 131
doc.: IEEE 802.22-05/0105r1
Submission
Clustering: Physical Cluster (cont.)
• Creation of Physical Clusters is totally localized at the BS– No direct involvement from
CPEs
• The BS groups together CPEs sensing “similar” characteristics of the incumbent signal– Could also be based on location
relative to the incumbent transmitter
CPE
PhysicalCluster
BS
November 2005
Carlos Cordeiro, Philips
Slide 132
doc.: IEEE 802.22-05/0105r1
Submission
Clustering: Physical Cluster (cont.)
• Based on the well-known k-means clustering algorithm
• The algorithm– Initially, no clustering
– CPEs report measurements to the BS (BLM-REP) which constructs incumbent profiles
– Then, the BS runs the clustering algorithm
Frequency
Rec
eive
d in
cum
ben
tsi
gn
al s
tren
gth
Far away (orlow power)incumbent
Nearby (orhigh power)incumbent
November 2005
Carlos Cordeiro, Philips
Slide 133
doc.: IEEE 802.22-05/0105r1
Submission
Clustering: Logical Cluster (cont.)
• Formed by CPEs belonging to different Physical Clusters
• Allows the BS to group those CPEs that are less likely to contend for the same airtime
• CPEs within a Logical Cluster perform the same “coexistence task”
BS
CPE
LogicalCluster
CBP at T1AllCBP at T2
CBP at T3ATSC NTSC All
Exemplary assignment forincumbent measurements:
Exemplary assignmentfor CBP:
DVB
PhysicalCluster
November 2005
Carlos Cordeiro, Philips
Slide 134
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 135
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 136
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 137
doc.: IEEE 802.22-05/0105r1
Submission
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– 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
November 2005
Carlos Cordeiro, Philips
Slide 138
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction
• The CMAC Protocol– Architecture– 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
November 2005
Carlos Cordeiro, Philips
Slide 139
doc.: IEEE 802.22-05/0105r1
Submission
Performance Evaluation
• All aspects of CMAC 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– 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
November 2005
Carlos Cordeiro, Philips
Slide 140
doc.: IEEE 802.22-05/0105r1
Submission
Throughput at the MAC SAP
• Evaluate the throughput of CMAC under varying number of bonded TV channels
• 1 BS and 127 CPEs
November 2005
Carlos Cordeiro, Philips
Slide 141
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 142
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 143
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 144
doc.: IEEE 802.22-05/0105r1
Submission
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
November 2005
Carlos Cordeiro, Philips
Slide 145
doc.: IEEE 802.22-05/0105r1
Submission
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 non-real time
November 2005
Carlos Cordeiro, Philips
Slide 146
doc.: IEEE 802.22-05/0105r1
Submission
Impact on QoS (cont.)
• The overall impact on average downstream delay is very small– QoS can be
satisfied to a large extent
(sec
)
Effect of Queuing
November 2005
Carlos Cordeiro, Philips
Slide 147
doc.: IEEE 802.22-05/0105r1
Submission
Impact on QoS (cont.)
• The overall impact on average upstream delay is not so small as in the downstream case– Despite of
that, QoS can still be satisfied to a significant extent
(sec
)
November 2005
Carlos Cordeiro, Philips
Slide 148
doc.: IEEE 802.22-05/0105r1
Submission
Handling of Incumbents
• Evaluate the detection, notification and recovery capability of CMAC
• 1 BS and 9 CPEs
• TV station starts in-band operation at a random time– Incumbent is detected
during quiet period
November 2005
Carlos Cordeiro, Philips
Slide 149
doc.: IEEE 802.22-05/0105r1
Submission
Handling of Incumbents (cont.)
• Network operation is quickly restored– BS and
unaffected CPEs switch to Backup Channel
– CPEs who do not receive switch message go to Backup Channel after timeout (2 frames)
Channel A Channel B
November 2005
Carlos Cordeiro, Philips
Slide 150
doc.: IEEE 802.22-05/0105r1
Submission
Handling of Incumbents (cont.)
• Evaluate the dynamics of channel bonding – Together with
handling of incumbents
– Network can switch to one or more Backup Channel
Channel A Channel B
November 2005
Carlos Cordeiro, Philips
Slide 151
doc.: IEEE 802.22-05/0105r1
Submission
Presentation Outline
• Introduction– A Glimpse of IEEE 802.22
• The Cognitive PHY Proposal
• The Cognitive MAC Proposal
• Conclusions
November 2005
Carlos Cordeiro, Philips
Slide 152
doc.: IEEE 802.22-05/0105r1
Submission
Conclusions
• Proposed a PHY and MAC that addresses the requirements set forth by the 802.22 WG
• PHY– Based on OFDMA
• Spreaded OFDMA• O-QAM
– Flexible channel configurations (6, 12, and 18 MHz)– TV and Part 74 detection
• MAC– Coexistence is a key feature
• Incumbent protection• Self-coexistence
– CBP and IDRP protocols, superframes, support of channel bonding, etc.