IEEE 802.22 PHY Overview Date: 2010-07-06 Name Company Address Phone Email Authors: Zander (Zhongding) Lei Sung Hyun Hwang Institute for Infocomm Research (I 2 R) Electronics and Telecommunications Research Institute (ETRI) 1 Fusionopolis Way #21-01 Connexis, 138632, Singapore 138 Gajeongno, Yuseong-Gu, Daejeon, 305-700, KOREA 65-6408-2436 leizd@i2r.a-star.edu.sg 82-42-860-1133 shwang@etri.re.kr Notice: This document has been prepared to assist IEEE 802.22. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair Apurva N. Mody as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at patcom@ieee.org. Slide 1
Abstract TV Channel Characteristics IEEE 802.22 PHY Features Comparisons to IEEE 802.16/WiMax Conclusions Slide 2
TV Channels Multipath Channel Characteristics Frequency selective with large excessive delay Excessive delay (measurements in US, Germany, France*) Longest delay: >60 µsec 85% test location with delay spread ~35 µsec Low frequency (54~862 MHz) Long range (up to 100 km) Slow fading Small Doppler spread (up to a few Hz) R e la t iv e a t t e n u a t io n ( d B ) 0-5 -10-15 -20-25 Profile C * WRAN Channel Modeling, IEEE802.22-05/0055r7, Aug 05 Slide 3-30 -10-5 0 5 10 15 20 25 30 35 40 45 50 55 60 Excess delay (usec)
Robust OFDMA Design Longer symbol time PHY Features (1) 1/ f ~ 300 µsec*; CP ~ 75 µsec WiMAX: CP ~ 11.4 µsec Slow fading f ~3.3 khz (Robustness to ICI better than WiMax in 3.5 GHz) WiMAX: f ~11 khz (Overkilled in VHF/UHF band) High throughput Peak data rate per channel: 22.69 Mb/s (rate 5/6, 64-QAM) WiMAX: 15.84 Mb/s (rate 5/6, 64-QAM) * US 6 MHz TV channel Slide 4
Simple and Light Specs Single PHY mode: OFDMA Single FFT mode: 2048 Single antenna spec PHY Features (2) Heavy multiple antennas specs (MIMO or beamforming) are not support due to physical sizes of antenna structures at lower frequencies Linear burst allocation DS: little time diversity gain could be achieved across symbols due to channel changes slowly US: allocated across symbols to minimize the number of subchannels used by a CPE, hence reducing (EIRP) to mitigate potential interference to incumbent systems WiMAX: 2 dimension burst mapping Slide 5
Worldwide Operation TDD PHY Features (3) Support worldwide TV channels (6, 7, or 8 MHz) in the VHF/UHF broadcast bands from 54 MHz to 862 MHz Same frame/symbol structure, preamble/pilot pattern, FFT size, number of data/pilot subcarriers, modulation and coding, interleaving etc. Sampling frequency, carrier spacing, symbol duration, signal bandwidth, and data rates are scaled by channel bandwidth Slide 6
PHY Features (4) Adaptive Modulation and Coding Four CP factors: 1/4, 1/8, 1/16, and 1/32 3 modulations (QPSK, 16QAM, 64QAM) and 4 coding rates (1/2, 2/3, 3/4, 5/6) Mandatory CC + optional turbo (CTC or SBTC) and LDPC codes Turbo-block bit interleaver and subcarrier interleaver Maximize the distance between adjacent samples to achieve better frequency diversity Slide 7
PHY Features (5) Preamble, Pilot Pattern and Channelization 3 types preambles: superframe, frame, and CBP Tile pilot pattern For each symbol, every 7 useful subcarriers has a pilot For each subcarrier, every 7 symbols has a pilot Robust channel estimation combining 7 OFDMA symbols. Slide 8
Comparison to IEEE 802.16 Air Interface FFT Mode OFDMA Channel Profile (MHz) Burst Allocation Subcarrier Permutation Multiple Antenna Techniques Robustness to delay spread IEEE 802.22 OFDMA Single mode (2048) 6, 7, or 8 (one per regulatory domain) Linear Distributed with enhanced interleaver Not supported Strong (CP= 74.7 µsec) IEEE 802.16e OFDMA, OFDM, Single Carriers Multiple modes (2048, 1024, 512, 128) 28, 20, 17.5, 14, 10, 8.75, 7, 3.5, 1.25 Two dimensional Adjacent or distributed Support Multiplexing, space time coding, and beamforming Weak (CP= 22.8 µsec) Subcarrier Spacing (khz) 3.3 10.9 Slide 9
Comparison to Mobile WiMAX PHY Profile FFT Mode Sampling Frequency (MHz) Subcarrier Spacing (KHz) Useful Symbol Time (1/ f) (µsec) Max CP Time (µsec) Peak Data Rate (Mbps) Burst Allocation Subcarrier Permutation Multiple Antenna Techniques IEEE 802.22 OFDMA, 6 MHz 2048 6.9 3.3 298.7 74.7 22.7 Linear Distributed with enhanced interleaver Not supported WiMax OFDMA, 5 MHz 512 5.6 10.9 91.4 11.4 15.8 Two dimensional Adjacent or distributed Support Multiplexing, space time coding, beamforming Slide 10
Conclusions IEEE 802.22 standard is optimized for VHF/UHF TV channels to provide broadband services with up to 100km coverage Robust to large delay spread Robust to Doppler spread Simple and light specs Slide 11