January 2006 - IEEE 802 LAN/MAN Standards Committee

January 2006 doc.: IEEE 802.22-06/0005r1 A PHY/MAC Proposal for IEEE 802.22 WRAN Systems IEEE P802.22 Wireless RANs Date: 2006-01-17 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. 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If you have questions, contact the IEEE Patent Committee Administrator at patcom@iee.org. > Submission Slide 1 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 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 Yun Hee Kim ETRI Korea +82-31-201-3793 yheekim@khu.ac.kr Moon Ho Lee ETRI Korea +82-63-270-2463 moonho@chonbuk.ac.kr HyungRae Park ETRI Korea +82-2-300-0143 hrpark@mail.hangkong.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 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 Submission Slide 2 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Co-Authors Name Company Address Phone email 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 Korea +82 10 3279 5210 USA +1-972-761-7167 David Mazzarese Baowei Ji Submission Samsung Electronics Co. Ltd. Samsung Telecom America Slide 3 d.mazzarese@samsung.com Baowei.ji@samsung.com ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Presentation Outline • Introduction – A Glimpse of IEEE 802.22 • The PHY Proposal • The MAC Proposal • Conclusions Submission Slide 4 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Presentation Outline • Introduction – A Glimpse of IEEE 802.22 • The PHY Proposal • The MAC Proposal • Conclusions Submission Slide 5 ETRI, France Telecom, Philips, Samsung January 2006 Submission doc.: IEEE 802.22-06/0005r1 Slide 6 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 7 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 8 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Presentation Outline • Introduction – A Glimpse of IEEE 802.22 • The PHY Proposal • The MAC Proposal • Conclusions Submission Slide 9 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 PHY Outline • Overview • Channel bonding • Supper-frame, preamble, spreading • Preliminary OFDM parameters, data rates • Sub-Channelization, pilot insertion • Error Correction Coding • Multiple antenna • Sensing Submission Slide 10 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 PHY Overview • OFDMA both in uplink and downlink • QPSK, 16-QAM, and 64-QAM, spreaded-QPSK – OQAM is also being considered, but it has been submitted as a separate contribution • More than 30 sub channels per TV channel • Contiguous channel bonding upto 3 TV channels (and beyond in a stack manner) • Data rate range from 5Mbps to 70Mbps • TDD, FDD Randomizer Submission FEC Interleaver Slide 13 Modulation (constellation mapping) ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 or Turbo Code) - Multiple antenna system • channel bonding Submission Slide 14 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 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 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 16 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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: 70 Mbps • Minimum: 4.5 Mbps • Maximum: 3.94 bits/s/Hz • Minimum: 0.75 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 channels Maximum of 23 Mbps for 6 MHz Single TV channel BW of 6 MHz Partial bandwidth allocation Slide 17 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Bonding: Motivation • 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 November 18, 2005, study from Freepress and New America Foundation (entitled “Measuring the TV “White Space” Available for Unlicensed Use”) reveals that there exists a considerable amount of contiguous vacant TV channels (especially in the upper UHF band) • More can be expected in other countries Submission Slide 18 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Contiguous open spectrum available! Example: Jackson, Mississippi Source: “Measuring the TV ‘White Space’ Available for Unlicensed Wireless Broadband”, Nov 18, 2005, New America Foundation Submission Slide 19 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Bonding • Make opportunistic and simultaneous use of multiple contiguous TV channels • Benefits: – More data rate or range • Initial link-budget analysis showed that single-TV channel can not support full data rate (e.g., 18Mbps) upto 30 Km range – 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 20 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 21 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Capacity of aggregated channels as a given signal power is spread over more channels Submission Slide 22 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Bonding Scheme • 6, 12, 18 MHz channels • Constant inter-carrier spacing TV TV WRAN N-3 N-2 N-1 N N+1 N+2 N+3 N+4 • Depends on availability TV TV • Several receiver techniques to deal with flexible BW WRAN N-3 – Selectable analog filters – Up sampling digital filters N-2 N-1 N N+1 N+2 N+3 N+4 TV TV WAN N-3 Submission Slide 23 N-2 N-1 N N+1 N+2 N+3 N+4 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 24 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 FFT Mode for WRAN Systems No. of Bonded Channel 1 2 3 1K 1K 2K NA 2K 2K 4K 6K 4K 4K NA NA 6K 6K NA NA Basic FFT Mode Submission Slide 25 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 26 Time ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 27 TSYM ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 28 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 – Increase resiliency 3 to interferers 4 • Receiver structure dev3 Dev2 (16QAM) Dev4 (S-QPSK) Dev8 (64QAM) dev5 (16QAM) – MMSE – Approximate ML Submission dev 1 (64QAM) Dev7 (S-QPSK) dev6 (64QAM) Slide 29 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Fractional Bandwidth Usage • • If wireless microphones are in operation in TV channel, the WRAN systems may be clear the entire TV channel • The number of used sub-carriers is proportional to the fractional bandwidth • More details in this coming March meeting • Example: Incumbent or other CR user (except microphone user) TV channel Microphone user f 6 MHz Submission 6 MHz Fractional use of TV channel Slide 30 Unused(6 MHz) ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 • channel bonding needed to achieve long range ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Spectrum of the signal (before further filtering) Produced using a 6K FFT for a single TV channel Submission Slide 32 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 33 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 OFDMA Parameters/Single Channel (6MHz) Mode 1K 2K 4K 6K FFT Size 1024 2048 4096 6144 560 * k 840 * k Bandwidth (k = 1, 2, …, 6) k MHz Sampling Factor 8/7 No. of Used Subcarriers (including pilot, but not DC) 140 * k 280 * k Sampling Frequency 48/7 MHz Subcarrier Spacing 6.696 kHz(***) 3.348 kHz 1.674 kHz 1.116 kHz Occupied Bandwidth 6.696 kHz*140*k 3.348 kHz*280*k 1.674 kHz*560*k 1.116 kHz*840*k Bandwidth Efficiency(*) 93~94 % FFT Time 149.33 us 298.66 us 597.33 us 896 us Cyclic Prefix Time(**) 37.33 us 74.66 us 149.33 us 224 us OFDMA Symbol Time 186.66 us 373.33 us 746.66 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 34 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 OFDMA parameters – channel bonding Parameter 3 TV bands 2 TV bands 1 TV bands 18 21 24 12 14 16 6 7 8 Inter-carrier spacing, DF (Hz) 3348 3906 4464 3348 3906 4464 3348 3906 4464 FFT period, TFFT (ms) 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) 1104 (552,1,551) 736 (368,1,367) 368 (184,1,183) No. of used sub-carriers, NT = ND + NP 5040 3360 1680 No. of data sub-carriers, ND 4680 3120 1560 No. of pilot sub-carriers, NP 360 240 120 Occupied bandwidth (MHz) 16.884 19.698 22.512 11.256 Bandwidth Efficiency (%) Submission 13.132 15.008 5.628 6.566 7.504 93.8 Slide 37 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Data Rate • • • • Bandwidth = 6 MHz FFT size = 2048 Cyclic prefix mode = 1/4 No pilot, no quiet periods assumed Unit: Mbps Code Rate 7/8 5/6 3/4 2/3 1/2 64QAM 23.63 22.50 20.25 18.00 13.50 16QAM 15.75 15.00 13.50 12.00 9.00 QPSK 7.88 7.50 6.75 6.00 4.50 Modulation Data Rate = No. of used subcarriers * code rate * no. of bits per modulation symbol/OFDM symbol time Submission Slide 38 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Data Rate – Channel Bonding • • • • Bandwidth = 3*6 MHz FFT size = 2048 Cyclic prefix mode = 1/4 No pilot, no quiet periods assumed Unit: Mbps Code Rate 7/8 5/6 3/4 2/3 1/2 64QAM 70.89 67.50 60.75 54.00 40.50 16QAM 47.25 45.00 40.50 36.00 27.00 QPSK 23.64 22.50 20.25 18.00 13.50 Modulation Data Rate = No. of used subcarriers * code rate * no. of bits per modulation symbol/OFDM symbol time * no. of channel bonded Submission Slide 39 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Spectral Efficiency • • • • • Single channel bandwidth = 6 MHz FFT size = 2048 Cyclic prefix mode = 1/4 No pilot, no quiet periods assumed The spectral efficiency is same for all fractional BW mode Unit : bps/Hz Code Rate 7/8 5/6 3/4 2/3 1/2 64QAM 3.94 3.75 3.38 3.00 2.25 16QAM 2.63 2.50 2.25 2.00 1.50 QPSK 1.31 1.25 1.13 1.00 0.75 Modulation Spectral Efficiency = No. of used subcarrier*code rate*no. of bits per modulation symbol/OFDM symbol time/BW Submission Slide 40 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Minimum Peak Throughput per CPE • • • • • Bandwidth = 6 MHz FFT size = 2048 Cyclic prefix mode = 1/4 No. of CPE’s = 512 CPE’s/oversubscription ratio 50 ~ 11 CPE’s No pilot, no quiet periods assumed Unit : Mbps Code Rate 7/8 5/6 3/4 2/3 1/2 64QAM 2.15 2.05 1.84 1.64 1.23 16QAM 1.43 1.36 1.23 1.09 0.82 QPSK 0.72 0.68 0.61 0.55 0.41 Modulation Min. Peak Throughput = No. of used subcarriers*code rate*no. of bits per modulation symbol/OFDM symbol time/no. of CPE’s Submission Slide 41 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Subchannelization Subcarrier Allocation Uniformly 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 Submission Slide 42 Symbol ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 43 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 44 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 45 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 46 S0 S1 ETRI, France Telecom, Philips, Samsung SM January 2006 doc.: IEEE 802.22-06/0005r1 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 47 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Coding Scheme • Coding Scheme – Convolutional Code -> similar to the 802.16 – Optional: • LDPC Code • Duo Binary Turbo Code • Concatenated code • Code Rates – CC , R = 1/2, 2/3, 3/4, 5/6, 7/8 – LDPC, R = 1/2, 2/3, 3/4, 5/6, 7/8 – DTC, R = 1/3, 1/2, 2/3, 3/4, 5/6, 7/8 Submission Slide 48 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Encoder • LDPC Encoder • DB-CTC Encoder – Same to 802.16e – Puncturing pattern and CTC interleaver are also same to 802.16e ST p1 Information bits ST ET-1 A  1 T-1 B p2 C H matrix n  m m  p A B T  I D E C Submission Slide 49 p p p m  p ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Decoder • 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 50 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 51 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 52 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 53 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 54 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 55 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Summary: Gains brought by DTC • Duo-binary TC offers 3.5 to 4 dB over CC • 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 56 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Multiple Antenna Techniques for 802.22 Systems • Transmit Diversity Techniques • Adaptive Beam-Forming Techniques • Feasibility of the two techniques in 802.22 environments will be investigated. Submission Slide 57 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Multiple Antenna Techniques for 802.22 Systems : Transmit Diversity (1) • Advantages of Transmit Diversity – – – – Easily increases spectral efficiency by utilizing diversity gain Simple detection algorithm unlike spatial multiplexing schemes No limit on the number of Rx antennas ==> highly flexible No substantial increase in hardware complexity in both CPE and BS: the same antennas for receive diversity at BS can be used. • Open Loop: STC – Orthogonal code algorithms: Alamouti’s scheme (2Tx), Tarokh’s scheme (3, 4Tx) – Quasi-orthogonal code algorithm (4Tx) – STTC, etc. Submission Slide 58 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Multiple Antenna Techniques for 802.22 Systems : Transmit Diversity (2) • Closed Loop: – Most effective in fixed environments – Eigen-beamforming at base-station: best performance, however requires down-link channel information at transmitter. – Reduced-feedback methods: number of feedback bits can be reduced, with ~ 1dB performance loss – No feedback from the CPE for TDD due to reciprocity property • Considering the spectrum bands to be used for 802.22 systems, transmit diversity with two antennas seems most applicable. Submission Slide 59 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 Figure. Block diagram of an STBC-OFDM system Submission Slide 60 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : Simulation Conditions • • • • • Two Tx antennas 2K mode system used for simulation Delay profiles defined for 802.22 Fixed Doppler spectrum defined for 802.16a Channel estimation – Partitioned MMSE estimation performed by using the preamble – SNR in MMSE: 20dB – RMS delay parameter 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 61 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : STBC (1) 0 10 Modulation = QPSK No. of Rx Ant = 1 r = 0.7 -1 Uncoded BER 10 -2 10 -3 10 Performance gain: 3.7dB ~ 7.5dB at 10-2 ~ 10-3 BER Alamouti case Profile A Profile B Profile C Profile D No diversity case Profile A Profile B Profile C Profile D -4 10 -5 10 0 5 10 15 20 25 Eb/No Figure. BER performance of Alamouti’s scheme in 802.22 environments (QPSK, degree of correlation r = 0.7) Submission Slide 62 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : STBC (2) 0 10 Modulation = 16QAM No. of Rx Ant = 1 r = 0.7 -1 Uncoded BER 10 -2 10 -3 10 Performance gain: 3.4dB ~ 7.0dB at 10-2 ~ 10-3 BER Alamouti case Profile A Profile B Profile C Profile D No diversity case Profile A Profile B Profile C Profile D -4 10 -5 10 0 5 10 15 20 25 Eb/No Figure. BER performance of Alamouti’s scheme in 802.22 environments (16QAM, degree of correlation r = 0.7) Submission Slide 63 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : STBC (3) 0 10 Modulation = 64QAM No. of Rx Ant = 1 r = 0.7 -1 Uncoded BER 10 -2 10 -3 10 Performance gain: 3.1dB ~ 6.0dB at 10-2 ~ 10-3 BER Alamouti case Profile A Profile B Profile C Profile D No diversity case Profile A Profile B Profile C Profile D -4 10 -5 10 0 5 10 15 20 25 Eb/No Figure. BER performance of Alamouti’s scheme in 802.22 environments (64QAM, degree of correlation r = 0.7) Submission Slide 64 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : STBC (4) 0 10 Modulation = QPSK No. of Rx Ant = 1 -1 Uncoded BER 10 -2 10 -3 10 No diversity case Alamoti case(Profile A) Correlation = 0.0 Correlation = 0.4 Correlation = 0.7 Correlation = 0.9 -4 10 -5 10 0 5 10 15 20 25 Eb/No Figure. BER performance vs. degree of correlation in 802.22 environments (Profile A, QPSK) Submission Slide 65 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Transmit Diversity Performance Submission Slide 66 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Degree of Correlation vs. Antenna Separation 1.0 0.9 o Angular spread = 0.5 Degree of Correlation 0.8 0.7 0.6 o Angular spread = 1 0.5 0.4 0.3 o Angular spread = 2 0.2 o Angular spread = 4 0.1 0.0 0 2 4 6 8 10 12 14 16 18 20 Antenna Separation (wavelengths) Figure. Degree of correlation vs. antenna separation for various angular spreads (Laplacian model) Submission Slide 67 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Summary : Transmit Diversity • About 3 –7dB downlink gain with 2 transmit antennas for r=0.7, when employing open loop transmit diversity. • Additional 2.0 –2.5dB gain for r=0.7, when employing closed loop transmit diversity. • Even in a highly correlated case of r=0.9, the performance improvement is rather acceptable. Submission Slide 68 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Open Issues : Transmit Diversity • Does sufficient diversity always exist to realize the gains? – Further investigation is necessary but seems obtainable for higher frequency bands! – The angular spread due to local scattering will be less than 0.5o in 802.22 environments. – However, the scattering due to remote objects may increase the angular spread, which in turn decreases the degree of correlation. – Selective usage according to the spectrum band will be necessary. • Signaling format and pilot patterns to allow transmit diversity options need to be specified at very start of standardization process. Submission Slide 69 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Multiple Antenna Techniques for 802.22 Systems : Adaptive Beam-Forming (1) • 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 CPEs are fixed at known locations, their directions-ofarrival (DOAs) may easily be obtained and incorporated for adaptive beam-forming 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 beam-forming using an array with simple configuration. – 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. Submission Slide 70 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Multiple Antenna Techniques for 802.22 Systems : Adaptive Beam-Forming (2) • Adaptive array vs. Fixed-beam array – More Efficient CCI Suppression: Adaptive array system steers the main beam to the direction of a desired signal, while steering nulls to the directions of undesired signals. 1st co-channel interferer desired signal adaptive array fixed-beam 2nd co-channel interferer Figure. Adaptive array vs. fixed-beam array Submission Slide 71 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Adaptive Beam-Forming Algorithms • DOA Based Sample Matrix Inversion (SMI) Algorithm ˆ 1a q  ˆ R w u ˆ is the where a q  is the steering vector for incident angle q and R u estimated interference-plus-noise covariance matrix. • Reference Signal Based SMI Algorithm ˆ 1rˆ ˆ R w x xd ˆ is the estimated covariance where rˆxd is the correlation vector and R x matrix. – Reference signal is required! Submission Slide 72 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : Simulation Conditions • Antenna Array – Array type: Linear equi-spaced array with half wavelength spacing consisting of 8 antenna elements. – Root-MUSIC is used to estimate the DOAs of incident signals. – All incident signals are assumed to have zero elevation angle. • Angular Spread – Laplacian model – All clusters are assumed to have the angular spread of 0.3o. • Others – – – – Submission No. of OFDM symbols for reverse link preamble is 1. No. of sub-carriers assigned to users is 256. No. of sub-carriers per sub-band is 16 for reference signal method. No channel coding employed Slide 73 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Parameters for Simulation (1) (* : defined for adaptive beam-forming) PROFILE A Path 1 Path 2 Path 3 Path 4 Path 5 Path 6 Excess delay 0 3 msec 8 msec 11 msec 13 msec 21 msec 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 msec rms delay PROFILE B Path 1 Path 2 Path 3 Path 4 Path 5 Path 6 Excess delay -3 msec 0 2 msec 4 msec 7 msec 11 msec 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 msec rms delay Submission Slide 74 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Parameters for Simulation (2) (* : defined for adaptive beam-forming) PROFILE C Path 1 Path 2 Path 3 Path 4 Path 5 Path 6 Excess delay -2 msec 0 5 msec 16 msec 24 msec 33 msec 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 msec rms delay PROFILE D Path 1 Path 2 Path 3 Path 4 Path 5 Path 6 Excess delay -2 msec 0 5 msec 16 msec 22 msec 28 msec 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 msec rms delay Submission Slide 75 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : ABF Algorithms (1) 0 10 -1 Uncoded BER 10 -2 10 -3 Single Antenna DOA Based Reference Profile A Profile B Profile C Profile D 10 -4 10 0 5 10 15 20 25 SNR (dB) Figure. Comparison of BER performance for reverse link (INR = 25dB, interference DOAs =(20o, 30o), relative amplitude = (0dB, -3dB) ) Submission Slide 76 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : ABF Algorithms (2) Average Output SINR (dB) 24 22 20 Perfect interference cancellation : Output SINR = 24dB 18 16 14 12 10 DOA Based Algorithm Reference Signal Method 15 20 25 30 35 40 45 50 Azimuth Difference (Deg) Figure. Average output SINR vs. azimuth difference for reverse link ( Profile A, SNR = 15dB, INR = 25dB, relative amplitude = (0dB, -3dB) ) Submission Slide 77 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : ABF Algorithms (3) 0 10 -1 Uncoded BER 10 • Error distribution: truncated Gaussian -2 10 • Ref. signal method: insensitive due to self-healing nature No Errors o Amp Error = 10%, Phase Error = 10 o Amp Error = 20%, Phase Error = 20 o Amp Error = 30%, Phase Error = 30 Dashed line : DOA Based Algorithm Solid line : Reference Signal Method -3 10 • DOA based method: relatively insensitive -4 10 0 5 10 15 20 25 SNR (dB) Figure. Channel mismatch effect for reverse link ( Profile A, INR = 25dB, interference DOAs = (20o, 30o), relative amplitude = (0dB, -3dB) ) Submission Slide 78 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Performance Evaluation : ABF Algorithms (4) 0 10 -1 Uncoded BER 10 • Error distribution: truncated Gaussian -2 10 • Ref. signal method: extremely sensitive No Errors o Amp Error = 0.1%, Phase Error = 0.1 o Amp Error = 0.2%, Phase Error = 0.2 o Amp Error = 0.3%, Phase Error = 0.3 o Amp Error = 0.5%, Phase Error = 0.5 Dashed line : DOA Based Algorithm Solid line : Reference Signal Method -3 10 • DOA based method: relatively insensitive -4 10 0 5 10 15 20 25 SNR (dB) Figure. Effect of channel mismatch for forward link ( Profile A, INR = 25dB, interference DOAs = (20o, 30o), relative amplitude = (0dB, -3dB) ) Submission Slide 79 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Summary : Adaptive Beam-Forming • Efficient CCI cancellation by simple adaptive beamforming algorithms • In the reverse link, the reference signal method seems more effective due to – Simplicity in implementation – Robustness to channel mismatch or self-healing nature – However, in the case of a very large delay spread, the DOA based approach seems more preferred. – Selective usage may be necessary. • In the forward link, the DOA based method seems more desirable. – Robustness to the channel mismatch in the forward Submission Slide 80 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Open Issues : Adaptive Beam-Forming • A relevant vector channel model is necessary for reliable performance evaluation. • Reverse link preamble may be necessary to differentiate a desired signal from CCIs, which should be considered at very start of standardization process. Submission Slide 81 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Additional Physical Layer Features • Ranging • TPC Submission Slide 82 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Spectrum Sensing Submission Slide 84 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Distributed Sensing CSDU: Central Sensing Decision Unit Submission Slide 85 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 86 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Spectrum Sensing Architecture Omni Antenna Fine/Feature RFE Control MAC Energy Detection Submission Slide 87 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Spectrum Sensing Strategy Select candidates via Energy Detection •Sensing active channel during quite period •Sensing non-active/candidate/backup channels •Scanning during initial startup Fine/Feature detection for a selected channel Submission Slide 88 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 89 Decision ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 –Power –Modulation –Symbol frequency Feature detector 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  xDt • 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 90 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Local detection at each CPE • Signal detection – Signal x(k), that is transmitted over channel h(k), to be detected in presence of AWGN n(k) [signal absent hypothesis] H 0 : x(k )  n(k ) [signal present hypothesis] H 1 : x(k )  h(k ) * s(k )  n(k ) • h(k) is the impulse response of channel between Tx and CPE Rx • Measure received cyclic power spectrum at specific cycle frequencies – Specific cycle frequencies could be VSB Nyquist frequency (5.38 MHz), WRAN OFDM symbol frequency (x MHz), etc. – Declare signal sj present if spectral component detected at corresponding cycle frequencies { j} (decision fusion)  Sn0 ( f ),  2 0 0 | H ( f ) | S s ( f )  S n ( f ), S x ( f ) = 0,   H ( f   ) H * ( f   ) S  ( f ), s  2 2 Submission Slide 91   0, signal absent   0, signal present   0, signal absent   0, signal present ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Detection algorithm modes • Basic mode of detection algorithm – Detection of signal energy (from alpha = 0 spectral content) – Used in high SNR regimes for pilot/carrier/signature detection type schemes – Eg., pilot about 11 dB below at 310 KHz carrier offset from lower end frequency • Enhanced mode of detection algorithm – Detection of spectral features (spectral content at signal symbol frequency, carrier frequency, …) – Used in low SNR regimes – Especially useful during initialization procedures where BS is looking for an empty channel in possibly low SNR conditions Submission Slide 92 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Advantages of cyclostationary detection • Cyclic spectrum domain a richer domain for signal analysis than conventional power spectrum • Robust to noise – Stationary noise exhibits no cyclic correlations  S n0 ( f ),  | H ( f ) |2 S s0 ( f )  S n0 ( f ),   S x ( f ) = 0,   H ( f   ) H * ( f   ) S  ( f ), s   2 2   0, signal absent   0, signal present   0, signal absent   0, signal present • Better detector performance even in low SNR regions • Signal classification ability – Different signals have different cycle frequencies and exhibit distinct spectral characteristics • Can be used as an energy detector in alpha = 0 mode – Flexibility of operation Submission Slide 93 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 94 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Experimental Setup for DTV Detection 8VSB_SOURCE MULTIPATH SIMULATOR RECEIVER ATTENUATOR Submission Slide 95 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Experimental Test Results for DTV Detection (1) Based on DTV Laboratory Test Plan (Group C.1) “Static Echoes at various delays”. DELAY, ATTEN, DOPPLER, usec PATH 1 PATH 2 Submission dB ENERGY SENSOR, VSB SENSOR, DETECTION RATE, % DETECTION RATE, % Hz 0 0 0 -5.0 +3.0 +15.0 +30.0 0 0 0 0 0.05 0.05 0.05 0.05 PATH 1 POWER, dBm PATH 1 POWER, dBm -107 -100 -90 -107 -100 -90 100 100 100 100 100 100 100 100 100 100 100 100 95 95 100 100 100 100 100 100 100 100 100 100 Slide 96 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Experimental Test Results for DTV Detection (2) Based on DTV Laboratory Test Plan (Group D.1) “Static multipath with AWGN”. ENERGY SENSOR, VSB SENSOR, DELAY, PHASE, ATTEN, DETECTION RATE, % DETECTION RATE, % dB dB usec PATH 1 POWER, dBm PATH 1 POWER, dBm -107 PATH 1 PATH 2 PATH 3 PATH 4 PATH 5 PATH 6 Submission 0 0.066 0.073 0.091 0.026 0.088 0 326 151 299 298 235 0 5.6 6.1 6.9 14.8 12.2 100 Slide 97 -100 -90 -107 -100 -100 100 100 100 100 100 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Experimental Test Results for DTV Detection (3) Based on Doc.: IEEE802.22-05/0055r7. Profile A. ENERGY SENSOR, VSB SENSOR, DELAY, DOPPLER, ATTEN, DETECTION RATE, % DETECTION RATE, % Hz dB usec PATH 1 POWER, dBm PATH 1 POWER, dBm -107 -100 -90 -107 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 19.0 100 Slide 98 100 100 100 -100 -90 100 100 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Experimental Test Results for DTV Detection (4) Based on Doc.: IEEE802.22-05/0055r7. Profile B. ENERGY SENSOR, DELAY, DOPPLER, ATTEN, DETECTION RATE, % usec Hz dB PATH 1 POWER, dBm PATH 1 POWER, dBm -107 -100 -90 PATH 1 PATH 2 PATH 3 PATH 4 PATH 5 PATH 6 Submission 0 -3.0 2.0 4.0 7.0 11.0 0 0.1 0.13 2.5 0.17 0.37 0 6.0 7.0 22.0 16.0 20.0 VSB SENSOR, DETECTION RATE, % 100 Slide 99 100 100 -107 -100 -90 100 100 100 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 i 0 N 1 m k   P ( k , m) m 0 avg W.F. N 1  k   P ( k , m)  m k m 0 – Compute mean and “variance” Submission Slide 100 V>k*avg ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Part 74 detection (cont.) • Detection max( P(k , m))  k1 m 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 101 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Narrow-band detection (Part 74): Theoretical and simulated performance Submission Slide 102 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Probability of miss detection and false alarm Submission Slide 103 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 104 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 105 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 106 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 107 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Ideal Multiplier Submission Slide 108 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 LOmax = 10 dBm Submission Slide 109 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 LOmax = -30 dBm Submission Slide 110 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 111 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 112 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 113 7 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Feedback of sensing result and fusion rules • Option 1: Data fusion – – – Each sensing element makes raw observations but does not make a decision as to whether a signal is present or not It processes the raw observations and sends the processed information to the CSDU. For eg., each CPE may feed back quantized values of energy when in energy detector mode At the CSDU, the sensing reports from the Q reporting CPEs is fused using the decision: Q Declare signal present ( H 1) if  Ei  Tg; else declare H 0 i 1 • • Thresholds chosen so as to meet a pre-specified probability of false-alarm Option 2: Decision fusion – – – Each sensing element makes raw observations, processes these observations and makes a detection decision as to whether a signal is present or not It then sends the decision bit Di (1/0) to the CSDU At the CSDU, the individual decisions Di are fused into a final decision based on the following Q rule: Declare signal present ( H 1) if  D  T ; else declare H i g 0 i 1 • Submission Parameters chosen so as to meet a pre-specified probability of false-alarm Slide 114 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Presentation Outline • Introduction – A Glimpse of IEEE 802.22 • The PHY Proposal • The MAC Proposal • Conclusions Submission Slide 115 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 116 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 117 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 118 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 119 Packet Size: 1500 bytes ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 120 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 121 MAC Spectrum Manager ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 122 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Grouping and Matching • Multi-CH Resource Allocation US DS 1 2 MAP DS Burst#5 Burst#2 Burst#4 1’ N MAP DS Burst #3 time Burst #1 3 3’ Multi-CH Resource Allocation (FDD case): In order to scan all channel properly, SM (Spectrum Manager) allocates to CPE some redundant channel information in both FA-1 MAP and FA-3 MAP. N’ 6MHz Burst #6 BS 1’ 3’ 1 3 MAP overhead for Specifying multi channel allocation 3’ 3 1’ 1 CPE 1 Submission 2’ Slide 123 3’ 1’ 3 1 CPE 3 CPE 2 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Grouping and Matching (cont.) CH-1 MAP Burst#4 DS Burst#2 Burst#5 DS Burst #3 time Burst #1 Multi-CH Resource Allocation by CH Grouping: The size of both FA-1 MAP and FA-3 MAP can be reduced by using the Channel Grouping and Matching which is managed by SM (Spectrum Manager) CH-3 MAP Burst #6 After Matching and Grouping CH Matching 1’ 3’ 1 CH-1MAP Burst #3 3’ Burst #1 Burst#2 Before Matching and Grouping Submission CH Matching BS CPE 1 CH Grouping: To select a group of CPE’s that are assigned to the same channel 3 3 CH Matching: To select (US and DS) active set 1 for individual CPE Slide 124 CPE 3 CPE 2 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 125 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 126 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Bonding • Channel bonding offers enhanced capacity/data rate/range • To support channel bonding, we introduce a superframe structure that – Allows opportunistic and simultaneous use of multiple contiguous TV channels – Is dynamic and changes channel usage as channels become (un)available – Incorporates features that enable a multitude of mechanisms such as quiet period synchronization, better self-coexistence, and so on Submission Slide 128 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 • Quiet period schedule Occupied by Incumbent • Coexistence and superframe information • Number and size of frames Occupied by Incumbent • Information on periodic quiet periods SCH • ID an transmit power of transmitter Frame •Location configuration information Frame Frame Frame TV Channel Preamble SCH t 0 1 ... m-2 (Quiet) 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 129 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 130 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 131 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Network Entry and Initialization • BS and CPE initialization are key problems 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 132 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 133 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 134 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 140 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 141 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 142 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Measurements: Messages (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 143 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Measurements: Requests (cont.) • Single measurements requests 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 144 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Measurements: Reports (cont.) • Can be either regular or urgent • 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 145 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 146 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 and 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 147 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Channel Management (cont.)  Transition diagram for channel set ① The channel in null, active or candidate set becomes a member of occupied set as incumbent user appears. Incumbent service releases the channel and its quality is better than an existing member of the candidate set, then it is classified as a member of candidate set. Incumbent service releases the channel and its quality is worse than all member of the candidate set, 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 by new allocation to a WRAN service. The poorest channel in candidate set goes to a member of null set as its quality is worse than a new member of candidate set, which comes from null(4), active(7) or occupied(2) sets The channel is released due to the termination of its usage and its quality is better than an existing member of the candidate set. The channel is classified as a member of null set as the WRAN service releases the channel and its quality is worse than all member of the candidate set. ② ③ ④ ⑤ ⑥ ⑦ ⑧ Submission Slide 148 Null Set 8 6 3 4 1 Active Set 5 7 1 1 Candidate Set Occupied Set 2 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 149 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 few slides. – Incumbent Notification – Incumbent Detection Recovery Submission Slide 150 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 (hereby referred to Class B CPE) – Non-embedded • Currently addressed by the Part 74 Task Group • Based on the proposed MAC layer, we have developed a reliable embedded WMB approach comprised of three steps: – Class B CPE Scanning and detection – Class B CPE Notification – BS Acknowledgement and Dissemination Submission Slide 151 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 MAC Layer Detection of Wireless Microphones: Scanning and Detection • Class B CPE scans the desired channel in search for BS beacons – BS beacons contain quiet period schedules • A quiet period map is then constructed BS1 BS2 BS3 BS4 Time Quiet Period 802.22 Transmission Submission Slide 152 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 MAC Layer Detection of Wireless Microphones: Notification • Class B CPE starts sending WMBs during the quiet periods of BSs • WMBs contain information such as: – – – – – Submission Service start time Service duration Location information Transmit power Security key Slide 153 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 MAC Layer Detection of Wireless Microphones: Acknowledgement and Dissemination • Once the WMB is received by the BS or reported by any of its CPEs – Acknowledgement • The BS includes information in its own beacon about the presence of the wireless microphone • Network leaves the channel or reduces transmit power – Dissemination • Even after the network takes any appropriate action, the BS continues to advertise the wireless microphone operation in its beacon (for a time equivalent to Service Duration) Submission Slide 154 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 is then executed if Explicit Notification fails Submission Slide 155 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 156 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 157 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 158 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 159 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 .. . .. . Expedite Initialization Fz:MAP Fz:MAP QP Fz:MAP BLM-REP Fz:MAP QP BLM-REP Fz:MAP Submission Fz:MAP Slide 160 .. . Expedite Initialization QP Time-out CPE QP ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Incumbent Detection Recovery • The problem – How does the 802.22 cell recover from an incumbent appearance in a timely fashion? Submission Slide 161 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 162 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Self-Coexistence • The general problem TDMA Schedule Submission Slide 163 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 164 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 165 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 166 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 167 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 168 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 169 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 170 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 171 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 172 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 173 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Etiquette for Channel Assignment • CBP together with the renter-offerer mechanism is used to gather channel usage information in neighboring BSs • The etiquette is the algorithm used to select the appropriate channel that minimizes interference among collocated/neighboring WRANs Submission Slide 174 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 175 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 176 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Synchronization of Overlapping BSs (cont.) • Two steps in synchronization – Establishment – Confirmation and maintenance • Establishment – Done through self-coexistence quiet periods and CBP Transmission Offset ... Frame n at BS1: Frame m at BS2: ... Reception Offset Time Submission Slide 177 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Synchronization of Overlapping BSs (cont.) • Establishment – The synchronization rule guarantees that the system will converge Partial frame Slide Count Preamble SCH frame 0 ... frame 1 frame n-1 Preamble SCH frame 0 Slide Amount CBP Packet frame m-3 frame m-2 frame m-1 frame m Preamble SCH frame 0 Time – Frame slide messages are defined that allow synchronization to be accomplished – At the time of synchronization, overlapping quiet periods shall also be synchronized (this depends on the quiet period schedule) Submission Slide 178 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Synchronization of Overlapping BSs (cont.) • Synchronization is confirmed by receiving a CBP packet during the self-coexistence window MAC Slot Number k s k+1 FCH k+5 k+7 k+9 k+11 k+15 k+17 k+20 k+23 k+26 k+29 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 #4 Burst CPE #3 Burst CPE #5 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 179 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 180 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 181 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 182 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 183 NTSC Exemplary assignment for CBP: DVB All CBP at T1 CBP at T2 CBP at T3 ETRI, France Telecom, Philips, Samsung All January 2006 doc.: IEEE 802.22-06/0005r1 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 184 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 188 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 189 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 190 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 191 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 192 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 193 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 194 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 195 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 196 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 • 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 197 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 198 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 199 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 200 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 CBP/Synchronization • Evaluate the self-coexistence mechanisms of the proposed MAC – Synchronization – CBP in every frame 1 cell: • The number of overlapping 802.22 cells are progressively increased – Up to 4 cells are simulated – BSs and CPEs start at random 2 cells: • Network is fully loaded and traffic is uniform Submission Slide 201 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 CBP/Synchronization (cont.) 3 cells: 4 cells: Submission Slide 202 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 CBP/Synchronization (cont.) Local Drift Time Network Synchronization Time Submission Slide 203 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 CBP/Synchronization (cont.) • Simple scheduler • CBP together with Synchronization can provide significant performance improvements – Since CBP is under control of the BS, it can be made adaptive Submission Slide 204 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Presentation Outline • Introduction – A Glimpse of IEEE 802.22 • The PHY Proposal • The MAC Proposal • Conclusions Submission Slide 205 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 206 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Appendix A • WRAN maximum transmit power constraint for interference management and coexistence Submission Slide 207 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 208 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Individual maximum transmit power constraint, and joint maximum transmit 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 209 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Individual and joint transmit power constraints • Individual power constraint is required to meet the D/U minimum levels at the nearest TV receivers in co-channel and adjacent channel operations. – Guarantee that a single CPE transmitting over a 6 MHz band at the maximum transmit power constraint will just meet the interference requirements (in fact there is some margin due to fading). • Joint power constraint – In the case of simultaneous transmission of multiple CPEs in an aggregated bandwidth larger than 6 MHz, if each CPE uses the above individual power constraint, the D/U ratio will be too low at the nearest TV receiver. – Application: maybe rarely, mostly for coexistence of WRANs in some small overlapping area close to a Grade B/noise-protected contour with operation co-channel to a TV station. Submission Slide 210 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Justification of 150 m margin for first adjacent channels operation • Calculations show that [2] A CPE transmitting at 4W with TV operation on channel N should be: • • • • • • • • At least 10 km away from noise-protected contour co-channel to DTV operation At least 123 m away from noise-protected contour on N-1 of DTV operation At least 155 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 first adjacent channel 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 211 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Individual CPE transmit power constraint For one given CPE, determine the constraints on all bands incurred by possible TV operation on band N start 1 2 TV operation in band N? No Max power = 4W Yes  fill one column of Table 1 3 Yes 5 CPE in grade B contour + 150 m? No 4 • Add to list of disallowed bands: N-1, N, N+1 • Set max power constraint from EIRP(DTV) on other bands Distance > 4.7 km (NTSC)? Distance > 10 km (DTV)? No Yes 8 7 6 Update Table 1 Column N No Max power = 4W Distance > d_min? (NTSC or DTV) 9 Yes 10 12 No transmission on channel N Update Table 1 Column N Limit max transmit power as a function of distance -a æd ö Pt ,k ,max (dk ) = Po çç o ÷ ÷ ÷ çèdk ø÷ 11 Update Table 1 Column N 13 Update Table 1 Column N Submission Slide 212 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 location CPE operation on 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 8 No TV TV band 1 4W Not allowed (adjacent band) 4W 4W 4W 4W EIRP(-6) 4W TV band 2 4W Not allowed 4W 4W 4W 4W EIRP(-5) 4W TV band 3 4W Not allowed (adjacent band) 4W 4W @ 150 m DTV @ 44 m NTSC 4W 4W EIRP(-4) 4W TV band 4 4W EIRP(+2) 4W 4W @ 10 km DTV @ 4.7 km NTSC 4W 4W EIRP(-3) 4W TV band 5 4W EIRP(+3) 4W 4W @ 150 m DTV @ 31 m NTSC 4W 4W EIRP(-2) 4W TV band 6 4W EIRP(+4) 4W 4W 4W 4W Not allowed (adjacent band) 4W TV band 7 4W EIRP(+5) 4W 4W 4W 4W Not allowed 4W 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 213 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Maximum power constraint for all CPEs (out-of-band emission mask is assumed to meet the functional requirement 15.1.7 [1]) 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) (Outside grade B operation at distance d1) EIRP(-3) (Outside grade B operation at distance d2) x TV band 5 EIRP(+3) EIRP(+3) x TV band 6 Not allowed Not allowed x TV band 7 Not allowed Not allowed x CPE operation on 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 214 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Joint CPEs transmit power constraint • A single transmitting CPE induces power at TV receiver: Pr = Pt ,kdk- a Where dk 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 the same and coexisting WRANs given limited on the CPEs of all WRANs within a constraint area. Submission Slide 215 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Joint CPEs transmit power constraint Interference limit to incumbents exceeded Pt ,k = Po Pt ,k = Interference limit to incumbents below threshold Pt ,k Submission Slide 216 Po K Podo- a = å dk- a ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Joint CPEs transmit power constraint 4W Pt ,k = Po Pt ,k = Pt ,k Submission Slide 217 Po K Podo- a = å dk- a ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Required cooperation between WRAN BSs • WRANs determine overlapping area on co-channel operation close to a Grade B/noise-protected contour, and lists the CPEs in that area. å • Each WRAN estimates the weight wi = dk- a from the knowledge of the distance of its own CPEs to the protected contour. • WRANs exchange these values. • WRANs scale the maximum transmit power of their CPEs according to: Pt ,k Submission Podo- a = å wi Slide 218 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Ideal power constraint rule properties A: constraint area nmax: maximum allowed CPEs density A better closed-form expression of the power rule can be found later. Submission Slide 219 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 Appendix B • Coexistence with other LE systems (Contention-Based Protocol) Submission Slide 220 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 221 ETRI, France Telecom, Philips, Samsung January 2006 doc.: IEEE 802.22-06/0005r1 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 222 ETRI, France Telecom, Philips, Samsung

January 2006 - IEEE 802 LAN/MAN Standards Committee

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