Multi-Antenna and Channel Estimation Supports in Synchronization Channel IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE C802.16m-08/1162r1 Date Submitted: 2008-09-05 Source: Seunghee Han, Sungho Moon, Jin Sam Kwak, Wookbong Lee Voice: +82-31-450-1935 e-mail : {dondai; msungho; samji; wbong}@lge.com LG Electronics LG R&D Complex, 533 Hogye-1dong, Dongan-gu, Anyang, 431-749, Korea Venue: Re: PHY: Text; IEEE 802.16m-08/033, Call for Detailed Physical Layer Comments Purpose: This contribution proposes SDD text for SCH based on ToC in IEEE 802.16m-08/003r4. Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who 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 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: <http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and <http://standards.ieee.org/guides/opman/sect6.html#6.3>. Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and <http://standards.ieee.org/board/pat >.

Multi-Antenna and Channel Estimation Supports in Synchronization Channel

Contents Introduction Multi-Antenna Supports in SCH Channel Estimation from SCH BCH Decoding Performance Summary Text Proposal for 16m SDD

Introduction Description in the Current SDD In the Contribution 11.x.2.1.1.3 Coverage The coverage area of IEEE 802.16m SCH shall not be worse than the minimum of the required coverage for broadcasting channel, control channel and unicast data channel at channel conditions under considerations. 11.x.2.1.1.5 MIMO support and channel estimation IEEE802.16m SCH may support multi-antenna transmissions. Channel estimation supported from the SCH is FFS. In the Contribution Detailed simulation results Reasons for multi-antenna transmission in SCH Reasons for channel estimation support in SCH

Multi-Antenna Supports in SCH Necessity of MIMO Supports in SCH Minimum 2 TX antennas are defined in SRD. BCH and other data will be transmitted by multiple antennas. The SCH coverage should be larger than BCH or other channels. There are no reasons to give up this additional diversity without additional overhead. Cell ID Detection Performance Correct detection probability : Probability to choose a BS which received power is within 3 dB of the BS with the highest received power Approximately 3.5dB @ 1% error rate in TU6-120km/h Detailed simulation assumption in Annex A

Convergence Time Assumptions Observation Time interval for cell ID detection error to be less than 1% # of combined symbols for timing sync. = 1 Convergence time = 5ms * (# of combined symbols for the cell ID detection) Observation Multi-antenna transmission is necessary to reduce the convergence time.

Channel Estimation from SCH Necessity of Channel Estimation for SCH Negligible impact on the main functionalities of SCH, e.g., timing/freq. sync and cell ID detection SCH will be time/frequency-coherently located with BCH. The BCH decoding performance is closely related to the system-operable coverage. In order to increase the BCH decoding performance Frequency diversity >= 5MHz BW Transmit diversity : spatial, time, and frequency diversity Low code rate : strong coding or repetition  Needs for additional resources Under the condition enabling channel estimation of each antenna SFBC or STBC is the best way for BCH compared to other schemes. Optimal BCH decoding performance is guaranteed by Channel estimation in both SCH and reference signals with SFBC CE information can be used for other control or date channels. Channel Estimation only from Pilots for BCH Decoding Pilots are multiplexed with data and designed for the coverage of data channels. Power boosting for pilots are needed for satisfy the BCH coverage. Power boosting will be limited due to large PAPR from multiplexing pilot and data. PAPR-optimized SCH can help to solve it. Coverage losses are inevitable for data due to the power boosting.

BCH Decoding Performance Comparisons of Channel Estimation Performance Using both SCH and Pilot Using SCH only Using Pilot only Simulation Environments for BCH Decoding SCH structure : 2x repetition structure with CDD Antenna : 1Tx-2Rx, 2Tx-2Rx (uncorrelated) Modulation and coding : QPSK 1/12 Channel decoder : Max-Log-MAP with 8 iterations SCH-to-traffic PSD ratio : 12.04 dB or 0 dB 3 dB booting due to 2x repetition structure Pilot-to-traffic PSD ratio : 3 dB or 0 dB Number of SCH symbols : 1 Number of BCH symbols : 4 Number of information bits : 248 Interpolation : Perfect/Practical (DFT-based interpolation)

BCH Decoding Performance (cont’d) Observations Obviously, using SCH for CE provides significant gains TU6, 3km/h, 2Tx  From 2.1 dB to 3.8 dB gains according to power boosting In high speed and non-boosting cases in the next pages Similarly, CE from SCH can provide significant gains for BCH decoding. Boosting :: SCH : 12.04 dB , Pilot : 3 dB Boosting :: SCH : 12.04 dB , Pilot : 0 dB

BCH Decoding Performance (cont’d) High Speed Case (TU6, 120km/h) TU6, 120km/h, 2Tx  From 2.1 dB to 3.5 dB gains according to power boosting Boosting :: SCH : 12.04 dB , Pilot : 3 dB Boosting :: SCH : 12.04 dB , Pilot : 0 dB

BCH Decoding Performance (cont’d) Non-Boosting Cases SCH : only 3 dB due to 2x repetition CE from SCH provides gains even in non-booting cases. TU6, 3 km/h, Pilot : 0 dB TU6, 120 km/h, Pilot : 0 dB

Summary The SCH should be transmitted by multiple transmit antennas in order to satisfy the condition that the SCH has a better coverage than BCH or other channels. Multi-antenna transmission can provide better convergence times than that of single-antenna transmission. In order to enhance the BCH decoding performance with antenna diversity schemes, the SCH should be able to provide channel estimation information of the entire bandwidth during BCH decoding.

Text Proposal for IEEE802.16m SDD ============= Start of text proposal for C80216m-08/003r4================ [Replace the whole section 11.7.2.1.1.5 with the following texts] 11.7.2.1.1.5 MIMO support and channel estimation The IEEE802.16m SCH supports multi-antenna transmissions. The number of supported antennas is 2 or 4 (FFS). Channel estimation is supported from the SCH in order to support the control/data channel decoding, e.g., BCH decoding. ================== End of text proposal =============================

Annex A : SCH Simulation Environments Simulation Parameters Carrier frequency: 2.5GHz System bandwidth: 5MHz Sampling factor: 28/25 Sampling frequency: 5.6MHz Subcarrier spacing: 10.9375kHz FFT size: 512 CP length: 1/8*Tu, where Tu is effective OFDM symbol duration Number of used subcarriers: 424 Number of guard subcarriers: 88 Carrier frequency offset: random within 0ppm and ±3ppm Frame configuration: All DL signals, 5ms periodicity for Sync channel Number of antennas: 1Tx-1Tx, 2Tx-1Rx, 4Tx-1Rx Multi-antenna transmission: CDD (1/4*Tu shifts for 2Tx, 1/8*Tu shifts for 4Tx) Sync channel repetition: 2 (every even subcarrier is nulled) Power boosting to other data channel per antenna on Sync channel: 12.04dB (=16) for CDD, 12.04dB+10*log10(# of Tx antennas) dB # of cells: 1, 2, 3 <cellA(desired cell): 0dB, cellB: -6dB, cellC: -6dB>