Transcript IEEE C802.16m-08/1162

Multi-Antenna and Channel Estimation Supports in Synchronization Channel
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-08/1162
Date Submitted:
2008-09-05
Source:
Seunghee Han, Sungho Moon, Jin Sam Kwak, Wookbong Lee
e-mail : {dondai; msungho; samji; wbong}@lge.com
Voice: +82-31-450-1935
LG Electronics
LG R&D Complex, 533 Hogye-1dong, Dongan-gu, Anyang, 431-749, Korea
Venue:
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
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1
Multi-Antenna and Channel Estimation
Supports in Synchronization Channel
2
Contents






Introduction
Multi-Antenna Supports in SCH
Channel Estimation from SCH
BCH Decoding Performance
Summary
Text Proposal for 16m SDD
3
Introduction
 Description in the Current SDD
 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
4
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
AWGN, 3ppm, Practical time/freq sync,# of cells=1
0
0
TU6, 120km/h, 3ppm, Practical time/freq sync,# of cells=1
10
10
1Tx-1Rx
2Tx-1Rx
4Tx-1Rx
Prob. of detection error
Prob. of detection error
1Tx-1Rx
2Tx-1Rx
4Tx-1Rx
-1
10
-2
10
-3
10
-18
-1
10
-2
10
-3
-16
-14
-12
-10
-8
SNR[dB]
-6
-4
-2
10
0
5
-18
-16
-14
-12
-10
-8
SNR[dB]
-6
-4
-2
0
Convergence Time
TU6, 120km/h, CDD, FO=3ppm, Practial time/freq sync, # of cells=1
40
 Assumptions
35
30
Convergence time [ms]
 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
25
20
15
10
 Multi-antenna transmission is necessary to
reduce the convergence time.
5
0
TU6, 120km/h, CDD, FO=3ppm, Practical time/freq sync, # of cells=2
-9
-8
-7
-6
SNR [dB]
-5
-4
-3
40
1Tx-1Rx
2Tx-1Rx
4Tx-1Rx
35
1Tx-1Rx
2Tx-1Rx
4Tx-1Rx
35
30
30
Convergence time [ms]
Convergence time [ms]
-10
TU6, 120km/h, CDD, FO=3ppm, Practical time/freq sync, # of cells=3
40
25
20
15
25
20
15
10
10
5
5
0
1Tx-1Rx
2Tx-1Rx
4Tx-1Rx
-10
-9
-8
-7
-6
SNR [dB]
-5
-4
-3
6
0
-10
-9
-8
-7
-6
SNR [dB]
-5
-4
-3
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.
7
BCH Decoding Performance
 Comparisons of Channel Estimation Performance
Frequency
Time
Tx0 pilot
 Using both SCH and Pilot
 Using SCH only
 Using Pilot only
Tx1 pilot
BCH
 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)
8
.
.
.
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
TU6 3km/h, CR=1/12, QPSK
0
TU6 3km/h, CR=1/12, QPSK
0
10
10
-1
-1
10
BLER
BLER
10
-2
10
-3
10
-12
1Tx-2Rx,
1Tx-2Rx,
1Tx-2RX,
1Tx-2Rx,
2Tx-2Rx,
2Tx-2Rx,
2Tx-2RX,
2Tx-2Rx,
perfect ch
pilot only
SCH+pilot
SCH only
perfect ch
pilot only
SCH+pilot
SCH only
-2
10
-3
-10
-8
-6
-4
SNR per antenna [dB]
-2
10
0
9
-12
1Tx-2Rx,
1Tx-2Rx,
1Tx-2RX,
1Tx-2Rx,
2Tx-2Rx,
2Tx-2Rx,
2Tx-2RX,
2Tx-2Rx,
-10
perfect ch
pilot only
SCH+pilot
SCH only
perfect ch
pilot only
SCH+pilot
SCH only
-8
-6
-4
SNR per antenna [dB]
-2
0
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
TU6 120km/h, CR=1/12, QPSK
0
TU6 120km/h, CR=1/12, QPSK
0
10
10
-1
-1
10
BLER
BLER
10
-2
10
-3
10
-12
1Tx-2Rx,
1Tx-2Rx,
1Tx-2RX,
1Tx-2Rx,
2Tx-2Rx,
2Tx-2Rx,
2Tx-2RX,
2Tx-2Rx,
perfect ch
pilot only
SCH+pilot
SCH only
perfect ch
pilot only
SCH+pilot
SCH only
-2
10
-3
-10
-8
-4
-6
SNR per antenna [dB]
-2
10
0
10
-12
1Tx-2Rx,
1Tx-2Rx,
1Tx-2RX,
1Tx-2Rx,
2Tx-2Rx,
2Tx-2Rx,
2Tx-2RX,
2Tx-2Rx,
-10
perfect ch
pilot only
SCH+pilot
SCH only
perfect ch
pilot only
SCH+pilot
SCH only
-8
-6
-4
SNR per antenna [dB]
-2
0
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
TU6 3km/h, CR=1/12, QPSK
0
TU6 120km/h, CR=1/12, QPSK
0
10
10
-1
-1
10
BLER
BLER
10
-2
10
-3
10
-12
1Tx-2Rx,
1Tx-2Rx,
1Tx-2RX,
1Tx-2Rx,
2Tx-2Rx,
2Tx-2Rx,
2Tx-2RX,
2Tx-2Rx,
perfect ch
pilot only
SCH+pilot
SCH only
perfect ch
pilot only
SCH+pilot
SCH only
-2
10
-3
-10
-8
-6
-4
SNR per antenna [dB]
-2
10
0
11
-12
1Tx-2Rx,
1Tx-2Rx,
1Tx-2RX,
1Tx-2Rx,
2Tx-2Rx,
2Tx-2Rx,
2Tx-2RX,
2Tx-2Rx,
-10
perfect ch
pilot only
SCH+pilot
SCH only
perfect ch
pilot only
SCH+pilot
SCH only
-8
-6
-4
SNR per antenna [dB]
-2
0
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.
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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 =============================
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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>
14