A PHY/MAC Proposal for IEEE WRAN Systems

A PHY/MAC Proposal for IEEE 802.22 WRAN Systems
Month Year doc.: IEEE yy/xxxxr0 January 2006 A PHY/MAC Proposal for IEEE WRAN Systems IEEE P Wireless RANs Date: Authors: Name Company Address Phone Martial Bellec France Telecom France Yoon Chae Cheong SAIT Korea Carlos Cordeiro Philips USA Chang-Joo Kim ETRI Hak-Sun Kim Samsung Electro-mechanics Joy Laskar Georgia Institute of Technology Notice: This document has been prepared to assist IEEE It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Carl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE Working Group. If you have questions, contact the IEEE Patent Committee Administrator at > Martial Bellec, France Telecom, et al John Doe, Some Company

Georgia Institute of Technology
Month Year doc.: IEEE yy/xxxxr0 January 2006 Co-Authors Name Company Address Phone Myung-Sun Song ETRI Korea Soon-Ik Jeon Gwang-Zeen Ko Sung-Hyun Hwang Bub-Joo Kang Chung Gu Kang KyungHi Chang Yun Hee Kim Moon Ho Lee HyungRae Park Denis Callonnec France Telecom France Luis Escobar Francois Marx Patrick Pirat Kyutae Lim Georgia Institute of Technology USA Youngsik Hur Martial Bellec, France Telecom, et al John Doe, Some Company

Co-Authors January 2006 Name Company Address Phone email
Dagnachew Birru Philips USA Kiran Challapali Vasanth Gaddam Monisha Ghosh Gene Turkenich Duckdong Hwang SAIT Korea Ashish Pandharipande Jeong Suk Lee Samsung Electro-Mechanics Chang Ho Lee Wangmyong Woo David Mazzarese Samsung Electronics Co. Ltd. Baowei Ji Samsung Telecom America Martial Bellec, France Telecom, et al

Presentation Outline Introduction The PHY Proposal The MAC Proposal
January 2006 Presentation Outline Introduction A Glimpse of IEEE The PHY Proposal The MAC Proposal Conclusions Martial Bellec, France Telecom, et al

January 2006 Martial Bellec, France Telecom, et al

The IEEE 802.22 From 18 Mbps to 24 Mbps
January 2006 The IEEE From 18 Mbps to 24 Mbps Propagation delays in excess of 300 µs Operates in TV bands 54 to 862 MHz 6 MHz, 7 MHz and 8 MHz channel bandwidth Martial Bellec, France Telecom, et al

Deployment Scenario Master/Slave relationship Entities
January 2006 Deployment Scenario Master/Slave relationship Entities Base Station (BS) Consumer Premise Equipment (CPE) 4W CPE transmit power Martial Bellec, France Telecom, et al

WRAN Hierarchy January 2006 Month Year doc.: IEEE 802.22-yy/xxxxr0
Public IP Network Service Provider IP Network HA AAA ACR WRAN BS CPE AAA : Authentication, Authorization and Account Server ACR : Access Control Router HA : Home Agent Martial Bellec, France Telecom, et al John Doe, Some Company

Deployment Scenario January 2006 Month Year
doc.: IEEE yy/xxxxr0 January 2006 Deployment Scenario WRAN Base Station Wireless MIC TV Transmitter -직면하게 되는 문제들을 이 그림에서 모든 것을 정리하자.. 문제를 이 슬라이드에게 정리하자. (모자라면 다음 장으로 연결해서) WRAN Base Station WRAN Repeater Typical ~33km Max. 100km Wireless MIC : WRAN Base Station : CPE Martial Bellec, France Telecom, et al John Doe, Some Company

PHY Overview OFDMA both in uplink and downlink
January 2006 PHY Overview OFDMA both in uplink and downlink QPSK, 16-QAM, and 64-QAM, spreaded-QPSK More than 30 sub channels Contiguous channel bonding upto 3 TV channels (and beyond in a stack manner) Data rate range from 5Mbps to 60Mbps TDD, FDD Martial Bellec, France Telecom, et al

What We Have Proposed …. Adaptive OFDMA Known and proven technology
January 2006 What We Have Proposed …. Adaptive OFDMA Known and proven technology for broadband fixed/mobile wireless access (e.g., IEEE d/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) Martial Bellec, France Telecom, et al

Advantages of Adaptive OFDMA Proposal
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 Martial Bellec, France Telecom, et al John Doe, Some Company

System Parameters: Proposed
Month Year doc.: IEEE yy/xxxxr0 January 2006 System Parameters: Proposed Parameters Specification Remark Frequency range 54~862 MHz Service coverage Typical range 33 km, Bandwidth Mandatory: 6, 7, 8 MHz with channel bonding Optional: fraction BW Allows the fractional use of TV channel and channel bonding up to 3 TV channels Data rate Maximum: 70 Mbps Minimum: 4.5 Mbps Maximum of 23 Mbps for 6 MHz Spectral Efficiency Maximum: 3.94 bits/s/Hz Minimum: 0.75 bits/s/Hz Single TV channel BW of 6 MHz Modulation QPSK, 16QAM, 64QAM Transmit power Default 4W EIRP Multiple Access Adaptive OFDMA Partial bandwidth allocation FFT Mode 1024, 2048, 4096, 6144 Cyclic Prefix Mode 1/4, 1/8, 1/16, 1/32 Duplex TDD or FDD Network topology Point-to-Multipoint Network Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Bonding More data rate Multi-path Diversity Interference
January 2006 Channel Bonding More data rate Multi-path Diversity Small BW signal can have deep fade or flat fade Wider-bandwidth signal provides more frequency/multipath diversity Interference Wider-band reduces the amount of interference Martial Bellec, France Telecom, et al

Channel Bonding: Capacity
January 2006 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 Martial Bellec, France Telecom, et al

Channel Bonding 6, 12, 18 MHz channels Constant inter-carrier spacing
January 2006 Channel Bonding 6, 12, 18 MHz channels Constant inter-carrier spacing Depends on availability Several receiver techniques to deal with flexible BW Selectable analog filters Up sampling digital filters Martial Bellec, France Telecom, et al

Channel bonding structure
January 2006 Channel bonding structure 6K FFT over 3 TV channels 2K per TV channel Null out the outer carriers for 1 or 2 TV channels Fixed inter-carrier spacing Several implementation possibilities 6 MHz 12 MHz 18 MHz Martial Bellec, France Telecom, et al

Fractional BW Example January 2006
Month Year doc.: IEEE yy/xxxxr0 January 2006 Fractional BW Example 1, 2, 3, 4, 5, 6, 7, 8 MHz bandwidth More details in the March meeting Martial Bellec, France Telecom, et al John Doe, Some Company

PHY (Baseband) Architecture
Month Year doc.: IEEE yy/xxxxr0 January 2006 PHY (Baseband) Architecture Martial Bellec, France Telecom, et al John Doe, Some Company

Spectrum of the signal (before further filtering)
January 2006 Spectrum of the signal (before further filtering) Produced using a 6K FFT for a single TV channel Martial Bellec, France Telecom, et al

802.22 proposed relative RF emission
January 2006 proposed relative RF emission Martial Bellec, France Telecom, et al

FFT Mode for WRAN Systems
Month Year doc.: IEEE yy/xxxxr0 January 2006 FFT Mode for WRAN Systems No. of Bonded Channel Basic FFT Mode 1 2 3 1K 2K NA 4K 6K Martial Bellec, France Telecom, et al John Doe, Some Company

OFDMA Parameters/Single Channel (6MHz)
Month Year doc.: IEEE yy/xxxxr0 January 2006 OFDMA Parameters/Single Channel (6MHz) Mode 1K 2K 4K 6K FFT Size 1024 2048 4096 6144 Bandwidth (k = 1, 2, …, 6) k MHz Sampling Factor 8/7 No. of Used Subcarriers (including pilot, but not DC) 140 * k 280 * k 560 * k 840 * 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 us us us 896 us Cyclic Prefix Time(**) 37.33 us 74.66 us 224 us OFDMA Symbol Time us us 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. Martial Bellec, France Telecom, et al John Doe, Some Company

OFDMA parameters – channel bonding
January 2006 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 FFT period, TFFT (ms) 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 13.132 15.008 5.628 6.566 7.504 Bandwidth Efficiency (%) 93.8 Martial Bellec, France Telecom, et al

Preamble Superframe preamble Frame preamble: 1-3 TV channels
January 2006 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 (short) (long) Martial Bellec, France Telecom, et al

Preamble Preamble has the repetition pattern in the time domain:
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 Martial Bellec, France Telecom, et al John Doe, Some Company

Spreaded QPSK/OFDMA Spread data over some sub-carriers (QPSK only)
January 2006 Spreaded QPSK/OFDMA Spread data over some sub-carriers (QPSK only) Hadamard Two-carrier FFT based unitary pre-coding Depending on the receiver structure, this can Increase capturing of multipath diversity Increase resiliency to interferers Receiver structure MMSE Approximate ML Martial Bellec, France Telecom, et al

Preliminary Link Budget (LOS)
January 2006 Preliminary Link Budget (LOS) Difficult to achieve 19Mbps over 30Km without channel bonding Martial Bellec, France Telecom, et al

Superframe Structure January 2006
Martial Bellec, France Telecom, et al

Data Rate Bandwidth = 6 MHz FFT size = 2048 Cyclic prefix mode = 1/4
January 2006 Data Rate Bandwidth = 6 MHz FFT size = 2048 Cyclic prefix mode = 1/4 No pilot, no quiet periods assumed Unit: Mbps Code Rate Modulation 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 12.00 9.00 QPSK 7.88 7.50 6.75 6.00 4.50 Data Rate = No. of used subcarriers * code rate * no. of bits per modulation symbol/OFDM symbol time Martial Bellec, France Telecom, et al

Data Rate – Channel Bonding
January 2006 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 Modulation 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 36.00 27.00 QPSK 23.64 22.50 20.25 18.00 13.50 Data Rate = No. of used subcarriers * code rate * no. of bits per modulation symbol/OFDM symbol time * no. of channel bonded Martial Bellec, France Telecom, et al

Spectral Efficiency Single channel bandwidth = 6 MHz FFT size = 2048
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 Modulation 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 2.00 1.50 QPSK 1.31 1.25 1.13 1.00 0.75 Spectral Efficiency = No. of used subcarrier*code rate*no. of bits per modulation symbol/OFDM symbol time/BW Martial Bellec, France Telecom, et al John Doe, Some Company

Minimum Peak Throughput per CPE
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 Modulation 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 1.09 0.82 QPSK 0.72 0.68 0.61 0.55 0.41 Min. Peak Throughput = No. of used subcarriers*code rate*no. of bits per modulation symbol/OFDM symbol time/no. of CPE’s Martial Bellec, France Telecom, et al John Doe, Some Company

Subchannelization Subcarrier Allocation Distributed Adjacent
January 2006 Subchannelization Subcarrier Allocation Distributed Subcarrier permutation Adjacent Subcarrier Permutation Band type Scattered type Martial Bellec, France Telecom, et al

Subchannelization (cont.)
January 2006 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 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 Martial Bellec, France Telecom, et al

Month Year doc.: IEEE yy/xxxxr0 January 2006 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). Martial Bellec, France Telecom, et al John Doe, Some Company

Month Year doc.: IEEE yy/xxxxr0 January 2006 Subchannelization (cont.) Scattered-Type Adjacent Subcarrier Allocation To achieve the multi-user diversity gain Only one bin allocated to each user Martial Bellec, France Telecom, et al John Doe, Some Company

Month Year doc.: IEEE yy/xxxxr0 January 2006 Subchannelization (cont.) Distributed Subcarrier Allocation Subcarriers are pseudo-randomly selected for frequency diversity Martial Bellec, France Telecom, et al John Doe, Some Company

Pilot Pattern Pilot pattern is varied with channel condition:
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Coding Coding Scheme Code Rates LDPC Code
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Coding Coding Scheme LDPC Code Convolutional Turbo Code Convolutional Code Concatenated Code : BCH+LDPC (CC or CTC) Code Rates For LDPC, R = 1/2, 2/3, 3/4, 5/6, 7/8 can be supported For CTC, R = 1/3, 1/2, 2/3, 3/4, 5/6, 7/8 can be supported For CC, R = 1/2, 2/3, 3/4, 5/6, 7/8 can be supported Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Coding (cont.) LDPC Encoder CTC Encoder Duo-binary CTC
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Coding (cont.) CTC Encoder LDPC Encoder Duo-binary CTC Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Coding (cont.) CTC Decoder LDPC Decoder January 2006
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Coding (cont.) CTC Decoder LDPC Decoder Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Coding (cont.) Performance Comparison: CTC vs. LDPC
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Coding (cont.) Performance Comparison: CTC vs. LDPC - Code rate of 1/2 over WRAN channel model C WRAN Channel profile C Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Coding (cont.) Performance Comparison: CTC vs. LDPC
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Coding (cont.) Performance Comparison: CTC vs. LDPC - Code rate of 2/3 over WRAN channel model C WRAN Channel profile C Martial Bellec, France Telecom, et al John Doe, Some Company

Duo-binary Turbo-codes Outline
January 2006 Duo-binary Turbo-codes Outline Duo-Binary Turbo Codes Internal interleaver Flexibility Performance Simulations Martial Bellec, France Telecom, et al

Duo-Binary Turbo-codes
January 2006 Duo-Binary Turbo-codes Information bits are encoded by couples Martial Bellec, France Telecom, et al

Duo-Binary Turbo-code
January 2006 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 Martial Bellec, France Telecom, et al

Internal Interleaver Algorithmic permutation
January 2006 Internal Interleaver Algorithmic permutation One equation, 4 parameters (P0, P1, P2, P3) Parameters selected such that interleaver is contention-free Adjusting the TC to a blocksize only requires modification of the 4 parameters Quasi-regular permutation (easy connectivity) Inherent parallelism i = 0, …, N-1, j = 0, ...N-1 level 1: if j mod. 2 = 0, let (A,B) = (B,A) (invert the couple) level 2: - if j mod. 4 = 0, then P = 0; - if j mod. 4 = 1, then P = N/2 + P1; - if j mod. 4 = 2, then P = P2; - if j mod. 4 = 3, then P = N/2 + P3. i = P0*j + P +1 mod. N Martial Bellec, France Telecom, et al

Flexibility Can be easily adjusted to any blocksize
January 2006 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 Martial Bellec, France Telecom, et al

January 2006 Flexibility The number of iterations can be adjusted for a better performance-complexity trade-off Martial Bellec, France Telecom, et al

Performance Duo-Binary TC, 8 iterations, Max-Log-MAP decoding
January 2006 Performance Duo-Binary TC, 8 iterations, Max-Log-MAP decoding IEEE e structured LDPC, BP decoding, 50 iterations AWGN, R=1/2, QPSK N=576 and 2304 (coded blocksize) Martial Bellec, France Telecom, et al

Short blocksize performance
January 2006 Short blocksize performance Hardware measurements Low BER (down to 10-11) are achievable without error floor Martial Bellec, France Telecom, et al

Simulation results Simulation parameters Constellation : 64 QAM
January 2006 Simulation results Simulation parameters Constellation : 64 QAM Coding rate : ½ Bandwidth : 7 MHZ Channel: 641 MHz Channel model: Profile A of WRAN Martial Bellec, France Telecom, et al

Duo-binary Turbo-codes vs Convolutional with OFDM/QAM modulation
January 2006 Duo-binary Turbo-codes vs Convolutional with OFDM/QAM modulation Martial Bellec, France Telecom, et al

Advantages of Duo-binary Turbo-codes
January 2006 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. Martial Bellec, France Telecom, et al

State of the art Duo-binary Turbo-code is a mature technology
January 2006 State of the art Duo-binary Turbo-code is a mature technology This technology has already been selected by several standardization groups IEEE / WiMAX; DVB-RCS; DVB-RCT; ETSI HIPERMAN Martial Bellec, France Telecom, et al

Summary: Gains brought by DTC
January 2006 Summary: Gains brought by DTC Duo-binary TC offers 3,5 to 4 dB When combined the gain is at least 4,5 dB that allows to increase the radius by 7,6 km (17%) with QPSK modulation in a Gaussian channel. Martial Bellec, France Telecom, et al

Transmit Diversity Multiple antennae needed only at the base station.
January 2006 Transmit Diversity Multiple antennae needed only at the base station. CPE has only one transmit/receive chain. Downlink uses transmit diversity methods. Uplink uses receive diversity for combining. Rate/ range increase for all CPEs with additional complexity only at the base-station. Especially useful where channel-bonding cannot be used for increased capacity. Martial Bellec, France Telecom, et al

Multiple Antenna Techniques for 802.22 Systems: STBC
Month Year doc.: IEEE yy/xxxxr0 January 2006 Multiple Antenna Techniques for Systems: STBC Why STBC schemes for systems? Easily increase spectral efficiency by utilizing transmit diversity gain Simple detection algorithm unlike the SM Techniques No limit on the number of Rx antennas ==> high flexibility No increase in hardware complexity: the same antennas for receive diversity at BS can be used Significantly increase cell radius STBC Schemes Orthogonal code algorithms: Alamouti’s scheme (2Tx), Tarokh’s scheme (3, 4Tx) Quasi-orthogonal code algorithm (4Tx), etc. Considering the spectrum band for systems, the Alamouti scheme employing two TX antennas seems most attractive. 그럼 이번 연구의 내용인 HPi system을 위한 적응 빔 형성 알고리즘에 대하여 설명하겠습니다. 이 그림은 HPi systme의 상향 링크용 스마트 안테나 알고리즘으로서 이는 High-resolution DOA algorithm에 기반을 두었습니다. 그래서 먼저 원하는 신호와 간섭 신호의 도래각을 추정한 후 원하는 신호의 방향으로는 main beam을 형성하고 간섭 신호의 방향으로는 null을 형성하는 알고리즘 입니다. 먼저 배열 안테나를 이용하여 신호를 수신한후, FFT를 취합니다. 그리고 원하는 신호의 주파수 bin을 추출신호가 있는 주파수를 선택하여 covariance matrix를 추정합니다. Covariance matrix에 대하여 eigen-decomposition 과정을 거친후 DOA를 추정합니다. 추정된 DOA를 통하여 간섭과 잡음의 covariance matrix를 생성 합니다. 그후, 생성된 covariance matrix를 이용하여 beam-forming weight vector를 계산합니다. 그리고 계산된 weight vector를 이용하여 beam pattern을 형성합니다. 이 알고리즘에 대하여 약간 구체적으로 살펴보겠습니다. Martial Bellec, France Telecom, et al John Doe, Some Company

Multiple Antenna Techniques for 802.22 Systems: Adaptive BF
Month Year doc.: IEEE yy/xxxxr0 January 2006 Multiple Antenna Techniques for Systems: Adaptive BF Why adaptive beam-forming for systems? Adaptive beam-forming can mitigate the effect of co-channel interference (CCI) inherent to OFDMA systems, thereby increasing frequency reuse factor close to unity. Since all CPE’s are fixed at known locations, their directions-of- arrival (DOA’s) may easily be obtained and incorporated for adaptive beam-forming without need to be tracked. Large cell in networks also makes beam-forming problem simple from 2D to 1D problem: easy DOA estimation (if necessary) or beam-forming using a simple array. In conjunction with the transmit diversity in the forward link and/or receive diversity in the reverse link, adaptive beam-forming may significantly increase cell radius, as required for systems. Adaptive beam-forming also significantly reduces multi-path delay spread, which enhances system efficiency. 그럼 이번 연구의 내용인 HPi system을 위한 적응 빔 형성 알고리즘에 대하여 설명하겠습니다. 이 그림은 HPi systme의 상향 링크용 스마트 안테나 알고리즘으로서 이는 High-resolution DOA algorithm에 기반을 두었습니다. 그래서 먼저 원하는 신호와 간섭 신호의 도래각을 추정한 후 원하는 신호의 방향으로는 main beam을 형성하고 간섭 신호의 방향으로는 null을 형성하는 알고리즘 입니다. 먼저 배열 안테나를 이용하여 신호를 수신한후, FFT를 취합니다. 그리고 원하는 신호의 주파수 bin을 추출신호가 있는 주파수를 선택하여 covariance matrix를 추정합니다. Covariance matrix에 대하여 eigen-decomposition 과정을 거친후 DOA를 추정합니다. 추정된 DOA를 통하여 간섭과 잡음의 covariance matrix를 생성 합니다. 그후, 생성된 covariance matrix를 이용하여 beam-forming weight vector를 계산합니다. 그리고 계산된 weight vector를 이용하여 beam pattern을 형성합니다. 이 알고리즘에 대하여 약간 구체적으로 살펴보겠습니다. Martial Bellec, France Telecom, et al John Doe, Some Company

Multiple Antenna Techniques for 802.22 Systems: Beam Forming
Month Year doc.: IEEE yy/xxxxr0 January 2006 Multiple Antenna Techniques for Systems: Beam Forming Why adaptive beam-forming for systems? Adaptive array system steers the main beam to the direction of a desired signal, while steering nulls to the directions of undesired interference signals. 그럼 이번 연구의 내용인 HPi system을 위한 적응 빔 형성 알고리즘에 대하여 설명하겠습니다. 이 그림은 HPi systme의 상향 링크용 스마트 안테나 알고리즘으로서 이는 High-resolution DOA algorithm에 기반을 두었습니다. 그래서 먼저 원하는 신호와 간섭 신호의 도래각을 추정한 후 원하는 신호의 방향으로는 main beam을 형성하고 간섭 신호의 방향으로는 null을 형성하는 알고리즘 입니다. 먼저 배열 안테나를 이용하여 신호를 수신한후, FFT를 취합니다. 그리고 원하는 신호의 주파수 bin을 추출신호가 있는 주파수를 선택하여 covariance matrix를 추정합니다. Covariance matrix에 대하여 eigen-decomposition 과정을 거친후 DOA를 추정합니다. 추정된 DOA를 통하여 간섭과 잡음의 covariance matrix를 생성 합니다. 그후, 생성된 covariance matrix를 이용하여 beam-forming weight vector를 계산합니다. 그리고 계산된 weight vector를 이용하여 beam pattern을 형성합니다. 이 알고리즘에 대하여 약간 구체적으로 살펴보겠습니다. adaptive array fixed-beam Figure. Adaptive array vs. fixed-beam array. Martial Bellec, France Telecom, et al John Doe, Some Company

Transmit Diversity Options: Summary
January 2006 Transmit Diversity Options: Summary Open Loop: STBC: Optimal only for 2 transmit antennae. Tone Interleaving: Performance gain is limited in channels with high frequency diversity. Closed Loop: Eigen-beamforming at base-station: best performance, however requires full down-link channel information at transmitter. Reduced-feedback methods: number of feedback bits can be reduced, with ~ 1dB performance loss Martial Bellec, France Telecom, et al

Transmit Diversity Performance
January 2006 Transmit Diversity Performance Martial Bellec, France Telecom, et al

Figure. Block diagram of an STBC-OFDM system.
Month Year doc.: IEEE yy/xxxxr0 January 2006 STBC-OFDM System Figure. Block diagram of an STBC-OFDM system. Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Parameters for Simulation
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Parameters for Simulation Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Parameters for Simulation (cont.)
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Parameters for Simulation (cont.) Martial Bellec, France Telecom, et al John Doe, Some Company

Simulation Conditions for STBC Processing
Month Year doc.: IEEE yy/xxxxr0 January 2006 Simulation Conditions for STBC Processing Two Tx Antenna Case: Alamouti’s scheme Doppler Spectrum: quasi-stationary Doppler spectrum defined for a Channel Estimation Channel estimation performed by using the preamble Partitioned MMSE using 16 sub-carriers SNR in MMSE: 20dB rms delay in MMSE: 9ms Others Two OFDM symbols used for forward link preamble Preamble symbol strength set to the average signal strength No channel coding employed 이는 두 신호의 방위각이 각각 10도와 20도 에서 입사한 경우 MUSIC Minimum-norm, CBF 알고리즘 성능을 비교한 것입니다. 이를 통하여 CBF는 도래각을 분리 추정할 수 없으며, High-resolution algorithm은 모두 수신 신호의 도래각을 분리, 추정함을 알 수 있습니다. Martial Bellec, France Telecom, et al John Doe, Some Company

Simulation Conditions for Adaptive Beam-forming
Month Year doc.: IEEE yy/xxxxr0 January 2006 Simulation Conditions for Adaptive Beam-forming Antenna Array Array type: Linear equi-spaced array with half wavelength spacing consisting of 8 antenna elements. Modified spatial smoothing is applied with the sub-array size of 7. Root-MUSIC is used to estimate the DOA’s of incident signals. All incident signals are assumed to have zero elevation angle. Channel Conditions Model for angular spread: Laplacian model All clusters are assumed to have the angular spread of 0.3o. Others Coincidence rate for signal identification set to 80%. No. of OFDM symbols for reverse link preamble is 1. No. of sub-carriers assigned to users is 128. No. of sub-carriers per sub-band is 16 for reference signal method. No channel coding employed 이는 두 신호의 방위각이 각각 10도와 20도 에서 입사한 경우 MUSIC Minimum-norm, CBF 알고리즘 성능을 비교한 것입니다. 이를 통하여 CBF는 도래각을 분리 추정할 수 없으며, High-resolution algorithm은 모두 수신 신호의 도래각을 분리, 추정함을 알 수 있습니다. Martial Bellec, France Telecom, et al John Doe, Some Company

Performance Evaluation: Alamouti’s Scheme
Month Year doc.: IEEE yy/xxxxr0 January 2006 Performance Evaluation: Alamouti’s Scheme Performance gain: 3.7dB ~ 7.5dB at 10-2 ~ 10-3 BER Figure. BER performance of Alamouti’s scheme in environments (No channel feedback, QPSK, r = 0.7) Martial Bellec, France Telecom, et al John Doe, Some Company

Performance Evaluation: Alamouti’s Scheme (cont.)
Month Year doc.: IEEE yy/xxxxr0 January 2006 Performance Evaluation: Alamouti’s Scheme (cont.) Figure. BER performance vs. degree of correlation in environments (no channel feedback, QPSK). Martial Bellec, France Telecom, et al John Doe, Some Company

Performance Evaluation: ABF Algorithms
Month Year doc.: IEEE yy/xxxxr0 January 2006 Performance Evaluation: ABF Algorithms 이는 두 신호의 방위각이 각각 10도와 20도 에서 입사한 경우 MUSIC Minimum-norm, CBF 알고리즘 성능을 비교한 것입니다. 이를 통하여 CBF는 도래각을 분리 추정할 수 없으며, High-resolution algorithm은 모두 수신 신호의 도래각을 분리, 추정함을 알 수 있습니다. Figure. Comparison of the BER performance (INR = 25dB, interference DOA’s =(20o, 30o), relative gains = (0dB, -6dB) ) Martial Bellec, France Telecom, et al John Doe, Some Company

Transmit Diversity Benefits
January 2006 Transmit Diversity Benefits About 6 –7dB downlink gain with 2 transmit antennae. About 11-12dB downlink gain with 4 transmit antennae. Similar gains on uplink, with receive-diversity implemented at base-station. Gains can be realized with about 4 bytes of feedback per user for 2 transmit antennae and 12 bytes per user for 4 transmit antennae. Martial Bellec, France Telecom, et al

Transmit Diversity: Open Issues
January 2006 Transmit Diversity: Open Issues Channel model: does sufficient diversity exists to indeed realize the gains? How often does channel feedback need to be send to transmitter? Signaling format to allow transmit diversity (open and close loop) options need to be specified at very start of standardization process. Martial Bellec, France Telecom, et al

Additional Physical Layer Features
Month Year doc.: IEEE yy/xxxxr0 January 2006 Additional Physical Layer Features Ranging TPC Martial Bellec, France Telecom, et al John Doe, Some Company

Design Review: PHY Layer
January 2006 Design Review: PHY Layer  Checking the functional requirements for IEEE WRAN WRAN Functional Requirements Our Proposal Minimum Peak Throughput DL: 1.5 Mbps/subscriber UL: 384 kbps/subscriber DL: < 2.15 Mbps/subscriber UL: < 2.15 Mbps/subscriber Spectral Efficiency Minimum: 0.5 bits/s/Hz Maximum: 5 bits/s/Hz Minimum: 0.75 bits/s/Hz Maximum: 3.94 bits/s/Hz Maximum Excess Delay Pre-echo: 3 us Post-echo: 60 us Maximum Cyclic Prefix Size: (BW=6 MHz, CP mode=1/4)  1K mode: us  2K mode: us  4K mode: us  6K mode: 224 us Martial Bellec, France Telecom, et al

January 2006 Spectrum Sensing Martial Bellec, France Telecom, et al

Proposed Spectrum Sensing Scheme
Month Year doc.: IEEE yy/xxxxr0 January 2006 Proposed Spectrum Sensing Scheme Dual Sensing Strategy: Energy detection and Fine/Feature detection Energy 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 Fine/Feature Detection 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 Martial Bellec, France Telecom, et al John Doe, Some Company

Spectrum Sensing Architecture
Month Year doc.: IEEE yy/xxxxr0 January 2006 Spectrum Sensing Architecture Omni Antenna Fine/Feature MAC RFE Control Energy Detection Martial Bellec, France Telecom, et al John Doe, Some Company

Spectrum Sensing Strategy
Month Year doc.: IEEE yy/xxxxr0 January 2006 Spectrum Sensing Strategy Select candidates via Energy Detection Sensing active channel during quite period Sensing non-active/candidate channels Scanning during initial startup Fine/Feature detection for a selected channel Martial Bellec, France Telecom, et al John Doe, Some Company

Energy Detection Method
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 LNA  Decision Martial Bellec, France Telecom, et al John Doe, Some Company

Cyclostationary Feature Detection
Month Year doc.: IEEE yy/xxxxr0 January 2006 Cyclostationary Feature Detection Large class of signals (eg., QAM, PSK, VSB, OFDM, CDMA, …) exhibit cyclostationary Cyclic power spectrum provides a richer domain for signal analysis than conventional power spectrum Signal detection and classification Stationary noise exhibits no cyclic correlations, while a signal of interest (eg., TV signal) being cyclostationary exhibits unique spectral properties at cycle frequencies Looking at cycle frequencies reveals specific ‘signal-only’ features Better detector performance even in low SNR regions Conventional spectrum density (left) vs cyclic spectrum density (right) in high SNR conditions (spectrum features at alpha = integer multiples of symbol and carrier frequencies) Conventional spectrum density (left) vs cyclic spectrum density (right) in low SNR conditions (spectrum features at alpha = integer multiples of symbol and carrier frequencies) Martial Bellec, France Telecom, et al John Doe, Some Company

Cyclostationarity based signal detection
Month Year doc.: IEEE yy/xxxxr0 January 2006 Cyclostationarity based signal detection 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 Signal attributes Power Modulation Symbol frequency Sliding N-pt FFT x(n) Correlate and average sum Feature detector Martial Bellec, France Telecom, et al John Doe, Some Company

DTV signal feature detection using field sync/correlation
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 Martial Bellec, France Telecom, et al John Doe, Some Company

Experimental setup for DTV detection
Month Year doc.: IEEE yy/xxxxr0 January 2006 Experimental setup for DTV detection 8VSB_SOURCE MULTIPATH SIMULATOR RECEIVER ATTENUATOR Martial Bellec, France Telecom, et al John Doe, Some Company

January 2006 Based on DTV Laboratory Test Plan (Group D.1)
Month Year doc.: IEEE yy/xxxxr0 January 2006 Based on DTV Laboratory Test Plan (Group D.1) “Static multipath with AWGN”. Martial Bellec, France Telecom, et al John Doe, Some Company

January 2006 Based on Doc.: IEEE802.22-05/0055r7. Profile A.
Month Year doc.: IEEE yy/xxxxr0 January 2006 Based on Doc.: IEEE /0055r7. Profile A. Martial Bellec, France Telecom, et al John Doe, Some Company

January 2006 Based on Doc.: IEEE802.22-05/0055r7. Profile B.
Month Year doc.: IEEE yy/xxxxr0 January 2006 Based on Doc.: IEEE /0055r7. Profile B. Martial Bellec, France Telecom, et al John Doe, Some Company

Month Year doc.: IEEE yy/xxxxr0 January 2006 Part 74 detection Part 74 devices occupy a small portion of the spectrum Thus, use spectral estimation and statistics of the estimated signal Spectral estimation using FFTs (windowing techniques can also be employed to better localize the spectrum) Perform FFT Average each freq bin Average across freq bin Compute mean and “variance” FFT avg W.F. V>k*avg Martial Bellec, France Telecom, et al John Doe, Some Company

Part 74 detection (cont.) Detection Theoretical performance
Month Year doc.: IEEE yy/xxxxr0 January 2006 Part 74 detection (cont.) Detection Theoretical performance Martial Bellec, France Telecom, et al John Doe, Some Company

Narrow-band detection (Part 74): Theoretical and simulated performance
Month Year doc.: IEEE yy/xxxxr0 January 2006 Narrow-band detection (Part 74): Theoretical and simulated performance Martial Bellec, France Telecom, et al John Doe, Some Company

Probability of miss detection and false alarm
Month Year doc.: IEEE yy/xxxxr0 January 2006 Probability of miss detection and false alarm Martial Bellec, France Telecom, et al John Doe, Some Company

MRSS: Multi-Resolution Spectrum Sensing
Month Year doc.: IEEE yy/xxxxr0 January 2006 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 Martial Bellec, France Telecom, et al John Doe, Some Company

 MRSS Schematics X ADC v(t)*fLO(t) MAC January 2006 Driver Amp Timing
Month Year doc.: IEEE yy/xxxxr0 January 2006 MRSS Schematics X  ADC z(t) y(t) x(t) Driver Amp w(t) CLK#2 v(t)*fLO(t) Timing Clock CLK#1 MAC Wavelet Generator Martial Bellec, France Telecom, et al John Doe, Some Company

Advantage of MRSS Full analog signal process
January 2006 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…) Martial Bellec, France Telecom, et al

Non-linear effect of MRSS
January 2006 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 Martial Bellec, France Telecom, et al

January 2006 Ideal Multiplier Martial Bellec, France Telecom, et al

January 2006 LOmax = 10 dBm Martial Bellec, France Telecom, et al

January 2006 LOmax = -30 dBm Martial Bellec, France Telecom, et al

January 2006 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 Martial Bellec, France Telecom, et al

MRSS Simulation Results Wireless Microphone (FM) Signal
Month Year doc.: IEEE yy/xxxxr0 January 2006 MRSS Simulation Results Wireless Microphone (FM) Signal 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 6 -100 -80 -60 -40 -20 20 40 Frequency Power Spectrum Magnitude (dB) -120 -110 -90 -70 -50 Frequency (Hz) PSD (dB) The spectrum of the wireless microphone signal The corresponding signal spectrum detected with the MRSS technique Martial Bellec, France Telecom, et al John Doe, Some Company

OFDM January 2006 Original MRSS Month Year doc.: IEEE 802.22-yy/xxxxr0
. 5 1 2 3 4 x 7 - F r e q u n c y P o w S p t m M a g i d ( B ) . 5 1 2 3 4 x 7 - F r e q u n c y ( H z ) P S D d B Original MRSS Martial Bellec, France Telecom, et al John Doe, Some Company

MAC Presentation Outline
January 2006 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 Martial Bellec, France Telecom, et al

January 2006 Introduction A MAC layer is proposed to be used for future IEEE WRANs Some aspects of MAC have been inspired by the IEEE 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. Martial Bellec, France Telecom, et al

January 2006 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 Packet Size: 50 bytes Packet Size: 1500 bytes Martial Bellec, France Telecom, et al

January 2006 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) Martial Bellec, France Telecom, et al

Protocol Stack Architecture
January 2006 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 Martial Bellec, France Telecom, et al

Protocol Stack Architecture (cont.)
January 2006 Protocol Stack Architecture (cont.) Flexible and scalable channel assignment Implementers decide on the algorithm Martial Bellec, France Telecom, et al

Channel Grouping and Matching
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Grouping and Matching Multi-CH Resource Allocation DS US 1 2 3 N 1’ 2’ 3’ N’ 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. 6MHz MAP MAP Burst #3 Burst #1 DS Burst#4 Burst#5 DS Burst#2 time Burst #6 1 3 1’ 3’ CPE 1 CPE 2 CPE 3 BS MAP overhead for Specifying multi channel allocation Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Grouping and Matching (cont.)
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Grouping and Matching (cont.) 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-1 MAP CH-3 MAP Burst #3 Burst #1 Burst#4 Burst#5 DS DS Burst#2 time Burst #6 After Matching and Grouping CH Matching 1 3 1’ 3’ CH Matching: To select (US and DS) active set 1 for individual CPE CPE 1 CPE 2 CPE 3 CH Matching BS CH Grouping: To select a group of CPE’s that are assigned to the same channel CH-1MAP Burst #3 Burst #1 Burst#2 Before Matching and Grouping Martial Bellec, France Telecom, et al John Doe, Some Company

Basic Terms and Definitions
January 2006 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 Martial Bellec, France Telecom, et al

Motivation for Channel Bonding
January 2006 Motivation for Channel Bonding The problem How to offer enhanced capacity and range? The fact Spectrum occupancy measurements conducted by Shared Spectrum Company from January/2004 to August/2005 have shown that: “There is a significant amount of spectrum available in continuous blocks that are 1 MHz and wider ” “A dynamic spectrum sharing radio with a low agility, contiguous waveform will provide high utility” The solution Simultaneous use of multiple contiguous TV channels Martial Bellec, France Telecom, et al

Superframe Control Header (SCH)
January 2006 Superframe Structure Superframe Control Header (SCH) TV channels being bonded Coexistence and superframe information Number and size of frames Information on periodic quiet periods ID an transmit power of transmitter Location configuration information Martial Bellec, France Telecom, et al

Frame Structure MAC is based on TDD/FDD frame structure
January 2006 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 Martial Bellec, France Telecom, et al

Time/Frequency Structure of a MAC Frame
January 2006 Time/Frequency Structure of a MAC Frame Martial Bellec, France Telecom, et al

Network Entry and Initialization
January 2006 Network Entry and Initialization The key problem Martial Bellec, France Telecom, et al

Network Entry and Initialization (BS)
January 2006 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 Martial Bellec, France Telecom, et al

Network Entry and Initialization (CPE)
January 2006 Network Entry and Initialization (CPE) 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 (REG-REQ message), perform other optional initialization procedures such as establish IP connectivity, establish time of day, and transfer operational parameters. Set up connections. Martial Bellec, France Telecom, et al

Network Entry and Initialization (CPE)
January 2006 Network Entry and Initialization (CPE) Downstream: Upstream: Martial Bellec, France Telecom, et al

Downstream (DS) Transmissions
January 2006 Downstream (DS) Transmissions DS = core messages + data (transmitted in bursts) Two core DS messages: DCD and DS-MAP Bursts identified by DIUC (Downstream Interval Usage Code) Each burst may contain data for several CPEs DCD (Downstream Channel Descriptor) Establishes association between DIUC and actual PHY parameters (e.g., modulation and coding) DS-MAP (Downstream map) Defines the usage (i.e., scheduling) of the downstream Critical, hence first message in each frame For self-coexistence purposes, the BS may choose to use part of DS subframe for CBP protocol operation Martial Bellec, France Telecom, et al

Upstream (US) Transmissions
January 2006 Upstream (US) Transmissions US = core messages + data (contention and bursts) Two core DS messages: UCD and US-MAP Bursts identified by UIUC (Upstream Interval Usage Code) The upstream can be segmented into several UIUC Contention-based Initialization, Bandwidth Request, Urgent Coexistence Situation (UCS), CBP slots (SCS) Data Bursts UCD (Upstream Channel Descriptor) Establishes association between UIUC and actual PHY parameters (e.g., modulation and coding) US-MAP (Upstream map) Defines the usage (i.e., scheduling) of the upstream Contains “grants”addressed to a particular CPE or a set of CPEs (e.g., for self-coexistence) Martial Bellec, France Telecom, et al

Bandwidth Management: Request/Grant Scheme
January 2006 Bandwidth Management: Request/Grant Scheme Self correcting No acknowledgement All errors are handled the same way (i.e., periodic aggregate requests) Bandwidth requests Are always per connection Can specify DS/US Traffic Constraint IEs for better self-coexistence Bandwidth grants Can be either per connection or per CPE Grants (given as durations) are carried in US-MAP messages CPE converts time into amount of data using information about the UIUC Martial Bellec, France Telecom, et al

Scheduling Services Unsolicited Grant Services (UGS)
January 2006 Scheduling Services Unsolicited Grant Services (UGS) For CBR and CBR-like flows (T1/E1) No specific bandwidth request issued by CPE Real-time Polling Service (rtPS) For rt-VBR-like service flows such as MPEG video CPEs are polled to meet delay requirements Non-real-time Polling Service (nrtPS) For non-real-time flows with better than best effort service such as bandwidth-intensive file transfer CPEs are polled and can use contention interval Best Effort (BE) E.g., Web surfing CPEs use contention interval only Martial Bellec, France Telecom, et al

Coexistence Two primary types Measurements can be classified as:
January 2006 Coexistence Two primary types With incumbents (TV service and Part 74 devices) With other overlapping 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) Martial Bellec, France Telecom, et al

Measurements Measurements form a key component of the MAC
January 2006 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, Measurement messages may be transmitted through multicast Allows the implementation of advanced features such as clustering Bandwidth efficient Martial Bellec, France Telecom, et al

Measurements (cont.) Bulk Measurement Request (BLM-REQ)
January 2006 Measurements (cont.) Bulk Measurement Request (BLM-REQ) Transmitted by the BS to CPEs Includes information such as Channels to measure Multiple single measurement requests Bulk Measurement Response (BLM-RSP) Transmitted by CPE to BS If needed, acknowledges the receipt of the BLM-REQ message Bulk Measurement Report (BLM-REP) Returns multiple single measurement reports Bulk Measurement Acknowledgement (BLM-ACK) Transmitted by BS to CPE Acknowledges receipt of measurement report Martial Bellec, France Telecom, et al

Measurements (cont.) Single measurements can be of various types
January 2006 Measurements (cont.) Single measurements can be of various types Signal specific measurement request TV system and Wireless microphones Beacon measurement request CBP, BS, and Wireless microphone beacons CPE statistics measurement request Stop measurement request Location configuration measurement request A range of parameters can be specified Martial Bellec, France Telecom, et al

January 2006 Measurements (cont.) There is almost a one-to-one correspondence between measurement requests and reports Some of the individual reports are: Signal specific measurement report TV/Wireless Microphone system type, measured value, precision, etc. Beacon measurement report Information on any CBP, BS, or Wireless microphone beacons received CPE statistics measurement report E.g., Packet error rate Location configuration measurement report If known, location information (GPS, triangulization, and so on) Martial Bellec, France Telecom, et al

January 2006 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 Martial Bellec, France Telecom, et al

Channel Management (cont.)
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Management (cont.) Channel Set: Definitions Active set 1: a set of used channels for a certain CPE Active set 2: a set of used channels for a certain BS Candidate set: a set of clean channels available for a certain CPE or BS Occupied set: a set of occupied channels by incumbent user which a certain CPE finds Disallowed Set: a set of channels whose access are not allowed by regulation Null set : a set of channels that are not classified as one of above five sets * Note: The allowed set is defined by union of candidate set and null set depending on channel’s SIR level Channel Set: Maintenance - Each BS maintains five channel sets: Active 1, Active 2, Occupied, Candidate, Null - Each CPE maintains four channel sets: Active 1, Active 2, Candidate, Occupied - If needed, each set is updated every quiet period (periodic or aperiodic) Martial Bellec, France Telecom, et al John Doe, Some Company

Channel Management (cont.)
Month Year doc.: IEEE yy/xxxxr0 January 2006 Channel Management (cont.) Transition diagram for channel set 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. Null Set Active Set Occupied Set Candidate Set 1 2 7 5 8 4 6 3 Martial Bellec, France Telecom, et al John Doe, Some Company

Coexistence with Incumbents
January 2006 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 Martial Bellec, France Telecom, et al

MAC Layer Detection of Wireless Microphones
January 2006 MAC Layer Detection of Wireless Microphones From the transmitter perspective, wireless microphone beacons (WMB) can be of two types Embedded device which has the additional capability of emitting WMBs Non-embedded Currently addressed by the Part 74 Task Group Based on the proposed MAC layer, we have developed an embedded WMB approach that: Reliably detects multiple collocated networks Upon sending WMBs, this mechanism causes minimal, if any, harmful interference to collocated networks Once either BSs or CPEs detect the WMB, a dissemination is made and all present networks vacate the channel Martial Bellec, France Telecom, et al

Incumbent Notification
January 2006 Incumbent Notification The problem How CPEs notify the BS about the presence of incumbents in a timely fashion? Two modes are proposed: Explicit Notification is executed first Implicit Notification in case Explicit Notification fails Martial Bellec, France Telecom, et al

Incumbent Notification: Explicit Mode
January 2006 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 Martial Bellec, France Telecom, et al

Incumbent Notification: Explicit Mode (cont.)
January 2006 Incumbent Notification: Explicit Mode (cont.) Martial Bellec, France Telecom, et al

Incumbent Notification: Explicit Mode (cont.)
January 2006 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 Martial Bellec, France Telecom, et al

Incumbent Notification: Implicit Mode
January 2006 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…. I found IU just had appeared, so I now have to search for new band…. By the way, do he know about that? Implicit signaling Martial Bellec, France Telecom, et al

Incumbent Notification: Implicit Mode (cont.)
Month Year doc.: IEEE yy/xxxxr0 January 2006 Incumbent Notification: Implicit Mode (cont.) Short Implicit Normal Implicit BS CPE BS CPE QP D . BLM-REP Fz:MAP Time-out Fx:Null Initialization U QP QP Fx:MAP Fx:MAP Time-out Fx:MAP Fz:MAP . . Initialization Fz:MAP QP QP Fz:MAP BLM-REP Fz:MAP Martial Bellec, France Telecom, et al John Doe, Some Company

Incumbent Detection Recovery
January 2006 Incumbent Detection Recovery The problem How does the cell recover from an incumbent appearance in a timely fashion? Martial Bellec, France Telecom, et al

Incumbent Detection Recovery (cont.)
January 2006 Incumbent Detection Recovery (cont.) The Incumbent Detection Recovery Protocol (IDRP) Introduces the concept of Candidate/Backup Channel(s) The 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 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 Martial Bellec, France Telecom, et al

Self-Coexistence The general problem January 2006 TDMA Schedule
Martial Bellec, France Telecom, et al

Self-Coexistence (cont.)
January 2006 Self-Coexistence (cont.) Indeed a major issue E.g., h Becomes even more critical in given The large coverage range Its unlicensed nature Directional antennas at CPEs do not address the problem Martial Bellec, France Telecom, et al

January 2006 Self-Coexistence (cont.) Some approaches to better self-coexistence Over the backhaul (i.e., wired) Pros can wash its hands (throw the “hot potato” to somebody else) Cons Will there be really a “common backhaul” between competing WISPs? Can rely on that? What if this “common backhaul” is down? Can 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 Built-in and self-healing system More complex MAC layer (but just a little more) Martial Bellec, France Telecom, et al

January 2006 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 Martial Bellec, France Telecom, et al

January 2006 Self-Coexistence (cont.) BS beacon based Implemented through overheard BS beacons BS beacons carry various information: Channels used Quiet periods Frame information Transmit power level If needed, can use sensing antenna for this purpose Allows better TPC and sharing in frequency only Case 1: Case 2: Martial Bellec, France Telecom, et al

January 2006 Self-Coexistence (cont.) Coexistence Beacon Protocol (CBP) CBP is executed by CPEs but under BS control CPEs transmit coexistence packets with information about 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 CBP beacon CBP beacon Martial Bellec, France Telecom, et al

January 2006 Self-Coexistence (cont.) Martial Bellec, France Telecom, et al

But what does the CPEs do with this information?
January 2006 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 Martial Bellec, France Telecom, et al

Then, what does the BS do about all this?
January 2006 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 Martial Bellec, France Telecom, et al

Resource Renting When Then
January 2006 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) Martial Bellec, France Telecom, et al

Resource Offering Step-by-step procedure between Offeror and Renter
January 2006 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 CBP Resource Renting Request Resource Renting ACK Renter CBP Martial Bellec, France Telecom, et al

Etiquette for Channel Assignment
January 2006 Etiquette for Channel Assignment The renter-offerer mechanism is used to gather channel usage information in neighboring BSs The etiquette is then used to select the appropriate channel that minimizes interference among collocated/neighboring WRANs Martial Bellec, France Telecom, et al

Etiquette Example January 2006 N2: 1,5,6 N1: 1,2,3 1,3,4,6,7 N3: 1,4,8
Neighbor 1 Neighbor 2 Neighbor 3 Central Active Set 1,2,3 1,5,6 1,4,8 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) Martial Bellec, France Telecom, et al

Synchronization of Overlapping BSs
January 2006 Synchronization of Overlapping BSs The problem Frames of co-channel overlapping BSs are asynchronous, which makes coexistence even harder Numerous benefits to synchronization Incumbent protection Quiet period synchronization of overlapping BSs Improved detection Self-Coexistence Logical channel amongst overlapping BSs Efficient sharing of resources BS1: BS2: Time Martial Bellec, France Telecom, et al

Synchronization of Overlapping BSs (cont.)
January 2006 Synchronization of Overlapping BSs (cont.) Synchronization is proposed amongst multiple collocated networks Martial Bellec, France Telecom, et al

January 2006 Clustering Alleviate much of the redundancy involved in the execution of the coexistence mechanisms So, very suitable for Can be employed in all coexistence mechanisms, except for the protection of Wireless Microphone services Based on key observations Sensing outcome of close-by CPEs are likely to be “similar” CPEs are stationary It is a two-step process conducted by the BS Formation of Physical Cluster Formation of Logical Cluster Martial Bellec, France Telecom, et al

Clustering: Physical Cluster (cont.)
January 2006 Clustering: Physical Cluster (cont.) Creation of Physical Clusters is totally localized at the BS No direct involvement from CPEs The BS groups together CPEs sensing “similar” characteristics of the incumbent signal Could also be based on location relative to the incumbent transmitter Martial Bellec, France Telecom, et al

Clustering: Physical Cluster (cont.)
January 2006 Clustering: Physical Cluster (cont.) Based on the well-known k-means clustering algorithm The algorithm Initially, no clustering CPEs report measurements to the BS (BLM-REP) which constructs incumbent profiles Then, the BS runs the clustering algorithm Martial Bellec, France Telecom, et al

Clustering: Logical Cluster (cont.)
January 2006 Clustering: Logical Cluster (cont.) Formed by CPEs belonging to different Physical Clusters Allows the BS to group those CPEs that are less likely to contend for the same airtime CPEs within a Logical Cluster perform the same “coexistence task” Martial Bellec, France Telecom, et al

Security Sublayer Based on IEEE 802.16e/D12 security sublayer
January 2006 Security Sublayer Based on IEEE e/D12 security sublayer Generic security framework made specifically for BWA networks Meets all the security requirements identified for the WRAN Standard Deeply studied and improved by various security experts (including IEEE and IETF ones) Composed of two sublayers A Privacy Key Management protocol (PKM) which provides authentication, authorization and secure key distribution between the BS and the CPE An encapsulation protocol which provides data packets protection Martial Bellec, France Telecom, et al

Security Sublayer (cont.)
January 2006 Security Sublayer (cont.) Mutual Authentication of the devices Either using RSA and digital certificates Or using EAP and EAP-method specific credentials Authentication of the subscribers (optional) Using EAP and EAP-method specific credentials Authorization based on authenticated CPE and/or subscriber identity Give access to dedicated service flows Martial Bellec, France Telecom, et al

Security Sublayer (cont.)
January 2006 Security Sublayer (cont.) Data packets encryption Using strong cryptographic algorithms (AES) Management frames integrity protection Using keyed message authentication codes Protection against Deny of Service and other attacks Protection of management frames against forgery and replay attacks Protection of data frames against replay attacks Protection of EAP packets during subscribers authentication Protection of every key negotiation phase, using digital signatures and random numbers Martial Bellec, France Telecom, et al

Performance Evaluation
January 2006 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 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 Martial Bellec, France Telecom, et al

Throughput at the MAC SAP
January 2006 Throughput at the MAC SAP Evaluate the throughput of the MAC under varying number of bonded TV channels 1 BS and 127 CPEs Martial Bellec, France Telecom, et al

Throughput at the MAC SAP (cont.)
January 2006 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 Martial Bellec, France Telecom, et al

Channel Efficiency Evaluate the channel utilization
January 2006 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 Martial Bellec, France Telecom, et al

January 2006 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 Martial Bellec, France Telecom, et al

Network Joining Time (cont.)
January 2006 Network Joining Time (cont.) 1 BS and 127 CPEs BS is powered up at simulation startup CPEs power up at random times FRD requires joining time under 10 sec Martial Bellec, France Telecom, et al

January 2006 Impact on QoS Evaluate the impact of quiet periods and incumbents on QoS Traffic pattern A total of 3 Mbps constant aggregate US traffic DS traffic varies between 3 Mbps and 15 Mbps All 127 CPEs establish connections with BS Out of these, 4 real time (QoS) connections at 32 Kbps each Other connections are BE or non-real time Martial Bellec, France Telecom, et al

January 2006 Impact on QoS (cont.) The overall impact on average downstream delay is very small QoS can be satisfied to a large extent Effect of Queuing (sec) Martial Bellec, France Telecom, et al

January 2006 Impact on QoS (cont.) The overall impact on average upstream delay is not so small as in the downstream case Despite of that, QoS can still be satisfied to a significant extent (sec) Martial Bellec, France Telecom, et al

Handling of Incumbents
January 2006 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 Martial Bellec, France Telecom, et al

Handling of Incumbents (cont.)
January 2006 Handling of Incumbents (cont.) Network operation is quickly restored BS and unaffected CPEs switch to Candidate/Backup Channel CPEs who do not receive switch message go to Candidate/Backup Channel after timeout (2 frames) Channel A Channel B Martial Bellec, France Telecom, et al

Handling of Incumbents (cont.)
January 2006 Handling of Incumbents (cont.) Evaluate the dynamics of channel bonding Together with handling of incumbents Network can switch to one or more Candidate/Backup Channel Channel A Channel B Martial Bellec, France Telecom, et al

January 2006 CBP/Synchronization Evaluate the self-coexistence mechanisms of the proposed MAC Synchronization CBP in every frame The number of overlapping cells are progressively increased Up to 4 cells are simulated BSs and CPEs start at random Network is fully loaded and traffic is uniform 1 cell: 2 cells: Martial Bellec, France Telecom, et al

CBP/Synchronization (cont.)
January 2006 CBP/Synchronization (cont.) 3 cells: 4 cells: Martial Bellec, France Telecom, et al

January 2006 CBP/Synchronization (cont.) Network Synchronization Time Local Drift Time Martial Bellec, France Telecom, et al

January 2006 CBP/Synchronization (cont.) Simple scheduler CBP together with Synchronization can provide significant performance advantages Since CBP is under control of the BS, it can be made adaptive Martial Bellec, France Telecom, et al

January 2006 Conclusions Proposed a PHY and MAC that addresses the requirements set forth by the 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. Martial Bellec, France Telecom, et al

January 2006 Appendix A WRAN maximum transmit power constraint for interference management and coexistence Martial Bellec, France Telecom, et al

Place of proposed interference management module in the system
January 2006 Place of proposed interference management module in the system QoS scheduling & resource allocation (RRM): in opportunistic spectrum access channels in dedicated channels (for coexistence) Interference management module Footprints of incumbent and coexisting WRANs Radio map Module that computes the constraints relative to the protection of incumbents Database Set of minimum constraints for QoS scheduler optimization Sensing measurements Module that computes the constraints relative to coexistence Constraints from WRANs negotiation outcome Martial Bellec, France Telecom, et al

Joint maximum power constraint rule in constraint areas
January 2006 Joint maximum power constraint rule in constraint areas Martial Bellec, France Telecom, et al

Justification of 150 m margin
January 2006 Justification of 150 m margin Calculations show that [2] A CPE transmitting at 4W with TV operation on channel N should be: At least 10 m away from noise-protected contour co-channel to DTV operation At least 150 m away from noise-protected contour on N-1 of DTV operation At least 44 m away from noise-protected contour on N+1 of DTV operation At least 4.7 km away from Grade B contour co-channel to NTSC operation At least 44 m away from Grade B contour on N-1 of NTSC operation At least 31 m away from Grade B contour on N+1 of NTSC operation Thus a 150 m margin beyond the Grade B/noise-protected contours can be given to take care of all but 1 constraints, and would only affect a marginal number of potential WRAN customers. An additional margin can be given if needed based on accuracy of distributed sensing measurements, and to take care of outage due to fading. Martial Bellec, France Telecom, et al

January 2006 Step by step process for the determination of the interference protection constraints Spectrum usage map Distance/location information Incumbent presence information First layer of individual maximum transmit power constraints Table 1 of max powers for each CPE on all TV bands Using flowchart #1 and EIRP information Table 2 of max powers for all CPEs on all TV bands Second layer of individual maximum transmit power constraints Distance and area information Negotiation between WRANs: sharing of density and area information result of negotiation: dedicated channels (operating and backup) shared channels List of areas where simultaneous transmissions are critical List of CPEs in these areas and density of constraint area Computation of maximum transmit power control rules for the CPEs in each constraint area Power density of other unlicensed users in each constraint area Third layer of maximum transmit power constraints Possible set of rules: dedicated channels to some CPEs (respectively to WRANs) power control rule as a function of density of CPEs (per constraint area per TV band) below the critical density threshold where communication is not possible or channels cannot be shared by CPEs. simultaneous scheduling constraints by groups of CPEs within a WRAN Martial Bellec, France Telecom, et al

January 2006 Maximum power constraint for a single CPE operation (out-of-band emission mask is assumed to meet the functional requirement [1]) Table 1 (example) 1st layer of maximum power constraint 2nd layer of maximum power constraint To Table 2 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. Martial Bellec, France Telecom, et al

Table 2 (example) January 2006
Joint power constraint rule applies whenever CPEs share the same frequency band. Martial Bellec, France Telecom, et al

January 2006 Flowchart to determine the first layer of maximum transmit power constraints  fill one cell of Table 1 For one given CPE, determine the constraints on all bands incurred by possible TV operation on band N Martial Bellec, France Telecom, et al

Simple description of the power rule
January 2006 Simple description of the power rule A single transmitting CPE induces power at TV receiver: Where d is the distance of the CPE to the Grade B contour, and a is the path loss exponent. Let n be the density of CPEs in a local area (a few km2). Multiple transmitting CPEs: effective path loss exponent is decreased Maximum transmit power rule: Power at the nearest TV receiver: One rule can address interference to incumbent from same and coexisting WRANs given the knowledge of the density of CPEs of all WRANs within a constraint area. Martial Bellec, France Telecom, et al

Power constraint rule properties
January 2006 Power constraint rule properties A: constraint area nmax: maximum allowed CPEs density Martial Bellec, France Telecom, et al

January 2006 Appendix B Coexistence with other LE systems (Contention-Based Protocol) Martial Bellec, France Telecom, et al

DS Contention-Based Coexistence with LE Devices (Call Flow)
January 2006 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 Martial Bellec, France Telecom, et al

US Contention-Based Coexistence with LE Devices (Call Flow)
January 2006 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 Martial Bellec, France Telecom, et al

A PHY/MAC Proposal for IEEE WRAN Systems

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A PHY/MAC Proposal for IEEE WRAN Systems

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