1. Multi-Antenna and Channel Estimation Supports in Synchronization Channel
IEEE Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-08/1162r1
Date Submitted:
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Seunghee Han, Sungho Moon, Jin Sam Kwak, Wookbong Lee Voice:
{dondai; msungho; samji;
LG Electronics
LG R&D Complex, 533 Hogye-1dong, Dongan-gu, Anyang, , Korea
Venue:
Re: PHY: Text; IEEE m-08/033, Call for Detailed Physical Layer Comments
Purpose:
This contribution proposes SDD text for SCH based on ToC in IEEE m-08/003r4.
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2. Multi-Antenna and Channel Estimation Supports in Synchronization Channel

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

4. Introduction Description in the Current SDD In the Contribution
11.x Coverage
The coverage area of IEEE m 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 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

5. 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 1% error rate in TU6-120km/h
Detailed simulation assumption in Annex A

6. 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.

7. 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.

8. 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 : 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)

9. 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 : dB , Pilot : 3 dB
Boosting :: SCH : dB , Pilot : 0 dB

10. 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 : dB , Pilot : 3 dB
Boosting :: SCH : dB , Pilot : 0 dB

11. 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

12. 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.

13. Text Proposal for IEEE802.16m SDD
============= Start of text proposal for C80216m-08/003r4================
[Replace the whole section with the following texts]
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 =============================

14. Annex A : SCH Simulation Environments
Simulation Parameters
Carrier frequency: 2.5GHz
System bandwidth: 5MHz
Sampling factor: 28/25
Sampling frequency: 5.6MHz
Subcarrier spacing: kHz
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>