IEEE C802.16m-08/478
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Design on the Synchronization Channel for IEEE802.16m
Date
Submitted
2008-05-05
Source(s)
Seunghee Han
Voice: +82-31-450-1935
E-mail:
dondai@lge.com
msungho@lge.com
samji@lge.com
Sungho Moon
Jin Sam Kwak
LG Electronics
Re:
IEEE 802.16m-08/016r1 "Call for Contributions on Project 802.16m SDD" - Preambles
Abstract
This contribution describes many consideration points in the preamble design, and proposes
some candidates for IEEE 802.16m preamble for the document C802.16m-08/003r1.
Purpose
To be discussed and adopted by TGm for use in the IEEE 802.16m SDD
Notice
Release
Patent
Policy
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.
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
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contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16.
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<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>.
Design on the Synchronization Channel for IEEE802.16m
Seunghee Han, Sungho Moon, and Jin Sam Kwak
LG Electronics
1. Introduction
This document provides various aspects and views in designing a synchronization channel1 based on
discussions and numerical analyses. We briefly describe design criteria and discuss pros and cons in terms of
timing acquisition algorithms, frequency allocation methodologies, and multi-antenna supports. Based on
simulations and analysis results, an auto-correlation based CDD-type synchronization channel, which has a
1
Since there are different views on the location of the IEEE 802.16m synchronization channel, we use the general word “synchronization channel”
throughout this contribution instead of “preamble”.
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IEEE C802.16m-08/478
sector-common frequency allocation and supports a transparent multi-antenna transmission, is proposed in this
contribution. As a text proposal, we suggest some text and illustrations for the Draft IEEE 802.16m System
Description Document (SDD), C802.16m-08/003r1 [1].
2. Design Criteria for Synchronization Channels
In general, the main objective of synchronization channels (or signals) is to enable MSs to perform the
following fundamental functionalities during cell search operations;
 Time/frequency synchronization
 Detection of cell IDs which can provide best effort services with appropriate link budget
An example of flow chart for cell search procedures is depicted in Figure 1. In this procedure, we assume that
the synchronization signal has a form of N times (Nx) repeated waveforms in terms of a time-domain amplitude.
The synchronization channel with a signal of N x repeated waveforms in time domain is widely adapted in
several OFDM-based systems. The synchronization channel with a signal of N x repeated waveforms in time
domain is widely adapted in several OFDM-based systems. For example, the 16e preamble has three times
repeated waveforms in time domain [2].
SET INITIAL CARRIER FREQUENCY
(set Ntrial0=0)
COARSE TIMING SYNC
no
Ntrial0
>=
MaxTrial0 ?
Ntrial0
=
Ntrial0+1
no
>= λ0 ?
yes
yes
FREQUENCY OFFSET SYNC
(set Ntrial1=0)
Ntrial0=0
SHIFT THE NEXT CARRIER
FREQUENCY (SCAN
FREQUENCY RASTER)
DETECT CELL ID
DETECT ADDITIONAL INFO
(OPTIONAL)
no
no
>= λ1 ?
Ntrial1
=
Ntrial1+1
SHIFT THE NEXT CARRIER
FREQUENCY (SCAN
FREQUENCY RASTER)
Ntrial1
yes
>=
MaxTrial1 ?
Ntrial0=0
yes
FINE TIMING SYNC
DECODE BCH
Figure 1 An example of flow chart for search procedures
In addition, synchronization channels can be utilized to provide the following supplementary functionalities;
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IEEE C802.16m-08/478
 Phase reference for broadcast channel (BCH) decoding to reduce pilot overhead or to provide good
channel estimation performance in case that the synchronization channel is time/frequency-coherently
located with BCH.
 Time/frequency tracking during data communications
 Measurement for neighboring cells in scanning modes
 Additional system information, if needed
Since the cell search is the earliest step in the cellular communication, its performance would have an effect on
other remaining procedures. Therefore, it is natural that the synchronization channel should be optimized even
in the worst case.
Based on above discussions, we summarize the desirable criteria on synchronization channels to provide not
only the fundamental functionalities but also the supplementary ones as follows;
1)
2)
3)
4)
5)
Good correlation properties
Low complexity during cell search, especially in the timing acquisition step
Consideration of effects on the frequency offset
Low PAPR to extend the cell coverage by power boosting
Constant amplitudes for the synchronization sequences in frequency domain in order to provide the
optimal capability of channel estimation for BCH decoding
6) Feasibility of channel estimation for each transmit antenna considering the decoding performance on
BCH
7) Feasible synchronization even in the worst case such as a cell-edged MS scenario
3. Synchronization Channel Structures according to Timing Acquisition
Algorithms
The synchronization channel structure may be categorized into two cases according to the timing acquisition
algorithms;
 Cross-correlation based algorithm in case of N rep  1
 Auto-correlation based algorithm in case of N rep  2
In the following, we define N rep (=1,2,…) as the number of the repetitions corresponding to the signal
amplitude periodicity in terms of a time-domain waveform within an OFDM symbol. For example, the periodic
insertion in frequency domain with three/two subcarrier spacing result in N rep  3 / N rep  2 in time domain.
Although the CC (Cross-Correlation) based algorithm can be applied with a single or a few synchronization
signals in case of N rep  2 , we will not consider the case due to the ambiguous peaks from the repeated signal
waveform. The illustrations of ambiguous peaks using CC based algorithm in case of 2x repeated signal are
shown in Figure 2.
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Aperiodic auto-correlation by CC-based timing detection
1
0.9
0.8
Desired peak
Amplitude
0.7
0.6
Ambiguous peaks
0.5
0.4
0.3
0.2
0.1
0
0
100
200
300
400
500
600
Time shift
700
800
900
1000
Figure 2 Illustrations on ambiguous peak in 2x rep using CC
The CC based algorithm can be applied when one or a few known synchronization signals are pre-defined. The
CC based timing acquisition algorithm can be implemented by the following equation (1) under the assumptions
with a single known signal, a SISO transmission, and no multi-frame averaging.

dˆ  arg max R(d ) 0  d  N f  1 with R(d )   
M 1 ( m 1) L 1
d
 m 0


n  mL

p  n r  n  d   / P  d 


2
*
( N  ML) ,
(1)
 N 1
2
  r  n  d   , when d  0

where P  d    n 0
,
2
2

 P  d   r  d  1  r  d  N  1 , d  0
and p(n) / r (n) / M / L / N / d̂ / N f represent the known synchronization signal in time domain / the received signal
/ a partition index for the M-partial correlation2 / the length of the divided sequence due to partial correlation /
the length of the total known sequence / a detected timing / the frame length, respectively.
.
The AC (Auto-Correlation) based algorithm using the waveform repetition can be implemented by the following
equation (2) assuming a 2x repeated waveform.
 N /21
* 
N 
   r  d  n    r  d  n     / P  d  , when d  0
ˆ
2 
, (2)
d  arg max R(d ) 0  d  N f  1 with R(d )   n 0
 
d
R d 1  R  R , d  0
 old new
 
2
It is well known that the partial correlation concept is introduced to reduce the impact from a large initial frequency offset [3]
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IEEE C802.16m-08/478
*
where Rold
 
N 
 
N 
  r  d  1   r  d  1    , Rnew   r  d   1   r  d  N  1  ,
2 
2

 
 
 N 1
2
  r  n  d   , when d  0

and P  d    n 0
.
2
2

 P  d   r  d  1  r  d  N  1 , d  0
*
Pros and cons for CC and AC based algorithms are summarized as follows;
 CC based algorithm
 Pros
 It can obtain a sharpened peak in timing acquisition under very small frequency offset
environment. It means the coarse timing step can be skipped in the synchronization procedure.
 Cons
 The complexity increases significantly.
 In order to achieve the fundamental goal, i.e, cell search, of the synchronization channel, it
requires, at least, one additional channel either in time/frequency/code/space domain to carry
cell ID information. This is because it is not feasible to adapt multiple correlators for hundreds
of hypothesis tests during the timing detection from practical implementation perspective.
 Under a large frequency offset environment, the benefit of sharpened peak would disappear due
to partial correlation which could result in stubby peak.
 AC based algorithm
 Pros
 The complexity is very small.
 It is possible for the synchronization channel to consist of only a single OFDM symbol. In other
words, it does not require additional resources or channels.
 It can works well regardless of frequency offset effect due to differential operation. (see
equation (2))
 Cons
 Additional fine timing is required after cell ID detection.
Regarding complexity which is directly related to the battery consumption at MSs, a CC based algorithm has
much larger complexity than AC based one. For example, assuming 50000 samples during a radio frame with a
certain sampling rate, the required number of complex multiplications and additions with N  1024 by
equation (1) and (2) are given by Table 1.
Table 1 Comparison of the complexity during one radio frame (It deosn’t count the division by P(d) in
the equations (1) and (2))
# of complex multiplications
# of complex additions
CC based
51200000
51150000
AC based (2x rep.)
100512
100511
Ratio of saving (%)
50939.19 %
50889.95 %
Based on the above discussions, we prefer an AC based synchronization channel ( N rep  2 ).
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4. Discussion on Sector-specific vs. Sector-common Frequency Allocation
In this chapter, we discuss two types of synchronization channels, i.e., sector-specific and sector-common
frequency allocations. It is noted that the following discussion is based on the auto-correlation based
synchronization channel using repeated waveforms as discussed in Chapter 3.
The sector-specific frequency allocation means that each cell or sector segment can be identified according to
the frequency allocation of synchronization signals. For example, the current 16e synchronization signal is
transmitted in the sector-specific manner in which each part of frequency positions is corresponding to a
segment ID to accomplish the frequency reuse of 3. In detail, the preamble sequence of segment ID n is
transmitted in the subcarriers at 3k  n , where k is a running index 0 to 283 for 1024-FFT. In consequence,
each segment can be identified via the frequency position of the synchronization signals.
Meanwhile, the sector-common frequency allocation represents that all cell or sector segments have the same
frequency allocations.
The pros and cons for sector-specific and sector-common allocations are summarized as following;
 Sector-specific frequency allocation
 Pros
 The performance of channel estimation by synchronization channel might be improved by the
orthogonal positions when synchronization channel is utilized as a phase reference for decoding
BCH.
 Cons
 It could not work for cell-edged MSs in perspective of time/frequency synchronization due to
the destruction of the repeated waveforms. In consequence, this structure could result in worse
synchronization performance than the sector-common frequency allocation.
 More hypothesis tests might be required to estimate a frequency offset for all cases of the
sector-specific allocation.
 With CP-based timing detection,
 the performance will significantly be degraded due to the fact that the CP region is already
collapsed by ISI from previous symbol.
 It would not be feasible because the current IEEE802.16m system might allow various CP
length.
 Sector-common frequency allocation
 Pros
 The above problems from sector-specific frequency allocation can disappear. Moreover, the
sector-common frequency allocation can provide a SFN gain in perspective of time/frequency
synchronization by construction of repeated waveforms from sectors in a cell-edged MS
scenario in the synchronized network.
 Cons
 The performance of channel estimation by the synchronization channel might be marginally
degraded in comparison to the sector-specific frequency allocation when the synchronization
channel is utilized as a phase reference for decoding BCH.
Figure 3 shows an example of a cell-edged MS scenario which is one of the worst cases. The next Figure 4 and
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Figure 5, respectively, straightforwardly describe the destruction and construction of repeated waveforms
resulting from sector-specific- and sector-common allocations.
Segment 2
Segment 0
BS1
Segment 1
Segment 0
Segment 2
se
MS
BS0
Segment 1
Segment 2
Segment 0
BS2
Segment 1
Figure 3 An example of the worst case for cell-edged MS
Insert only 3m (m is integer)
Sector 0
3x repetitive waveform
...
Time domain waveform
...
A
-(3k+3) -(3k+1) -3 -2
-(3k+2)
-1
0
1
2
3
A
A={a(0) a(1) a(2) … }
3k 3k+1 3k+2
Frequency index
k: integer
Insert only 3m+1 (m is integer)
A
3x repetitive waveform
Sector 1
...
-(3k+3) -(3k+1) -3 -2
-(3k+2)
...
-1
0
1
2
3
B
B·exp(j2π·2/3)
3x repetitive waveform
Time domain waveform
...
B·exp(j2π·1/3)
B={b(0) b(1) b(2) … }
3k 3k+1 3k+2
Frequency index
k: integer
Insert only 3m+2 (m is integer)
Sector 2
Time domain waveform
...
C
C·exp(j4π·1/3)
C·exp(j4π·2/3)
C={c(0) c(1) c(2) … }
-(3k+3) -(3k+1) -3 -2
-(3k+2)
-1
0
1
2
3
3k 3k+1 3k+2
Frequency index
k: integer
At cell-edged MS,
Sector0+Sector1+Sector2
Non-repetitive waveform
Time domain waveform
...
D
...
D={d(0) d(1) d(2) … }
-(3k+3) -(3k+1) -3 -2
-(3k+2)
-1
0
1
2
3
3k 3k+1 3k+2
Repetitive waveform is destructed!
Frequency index
k: integer
Figure 4 Destruction of repeated waveforms in the sector-specific allocation (3 x repetitions)
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Insert only 2m (m is integer)
Sector 0
2x repetitive waveform
...
...
Time domain waveform
A’
A’
A’={a’(0) a’(1) a’(2) … }
-2
-(2k+1)
-(2k+2)
-1
0
1
2
2k 2k+1
Frequency index
k: integer
Insert only 2m (m is integer)
Sector 1
2x repetitive waveform
Time domain waveform
...
...
B’
B’
B’={b’(0) b’(1) b’(2) … }
-2
-(2k+1)
-(2k+2)
-1
0
1
2
2k 2k+1
Frequency index
k: integer
2x repetitive waveform
Insert only 2m (m is integer)
Time domain waveform
Sector 2
...
C’
C’
...
C’={c’(0) c’(1) c’(2) … }
-2
-(2k+1)
-(2k+2)
-1
0
1
2
2k 2k+1
Frequency index
k: integer
At cell-edged MS,
Sector0+Sector1+Sector2
2x repetitive waveform
...
-(2k+1)
-(2k+2)
...
-2
-1
0
1
2
Time domain waveform
D’
D’
D’={d’(0) d’(1) d’(2) … }
Repetitive waveform still remains
and link budget may be increased!
2k 2k+1
Frequency index
k: integer
Figure 5 Construction of repeated waveforms in the sector-common allocation (2 x repetitions)
While the performance loss of channel estimation from sector-common allocation would be marginal, the
problem from sector-specific allocation would be considerably critical. As discussed in Chapter 2, the
synchronization at cell-edge, which is the worst case, is a fundamental requirement while allowing a phase
reference for decoding BCH via Sync channel is an optional functionality.
The simulation results for a cell-edged MS scenario as seen in Figure 3 were depicted from Figure 6 to Figure 7.
The timing detection performances for a sector-specific frequency allocation with 3x repeated waveforms and
sector-common one with 2x repeated waveforms for the synchronization channel were shown under the
environments of TU6 3km/h and TU6 120km/h. It is noted that the sequence and structure for the sector-specific
allocation are the same as that of the IEEE 802.16e synchronization channel. The timing synchronization is
regarded as success when the detected timing is ranged within ±CP_DURATION. The detailed simulation
conditions can be found in Annex A. The notation Nsector and I ref / I oc , in these figures, represent the number
of sectors which have an effect on the target MS and the ratio of the referenced sector power to other sector
powers, in which the signals from other cells were modeled as AWGN, respectively. The referenced sector in
this simulation was assumed to be sector 0.
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TU6 3km/h, 1Tx/2Rx ant, FO=3ppm
0
10
Timing acquisition failure rate
-1
10
Increase of # of sectors
-2
10
Increase of # of sectors
Sector-common (2x rep), Nsector=1
Sector-common (2x rep), Nsector=2
Sector-common (2x rep), Nsector=3
Sector-specific (3x rep), Nsector=1
Sector-specific (3x rep), Nsector=2
Sector-specific (3x rep), Nsector=3
-3
10
-4
10
-12
-10
-8
-6
Iref/Ioc [dB]
-4
-2
0
Figure 6 TU6 3km/h, 1Tx/2Rx antennas, 3ppm frequency offset
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TU6 120km/h, 1Tx/2Rx ant, FO=3ppm
0
10
Timing acquisition failure rate
-1
10
Increase of # of sectors
-2
10
Increase of # of sectors
Sector-common (2x rep), Nsector=1
Sector-common (2x rep), Nsector=2
Sector-common (2x rep), Nsector=3
Sector-specific (3x rep), Nsector=1
Sector-specific (3x rep), Nsector=2
Sector-specific (3x rep), Nsector=3
-3
10
-4
10
-12
-10
-8
-6
Iref/Ioc [dB]
-4
-2
0
Figure 7 TU6 120km/h, 1Tx/2Rx antennas, 3ppm frequency offset
From the simulation results, we observe that
 Under a single dominant link scenario with one sector, the performance of timing acquisition for 2x
repeated structure is better than 3x repeated one by 1 dB of I ref / I oc .
 As increasing the number of sectors at cell edged MS, the acquisition performance is gradually
 degraded in case of the sector-specific frequency allocation due to the destruction of the repeated
waveform. Particularly in fully loaded cases which is Nsector=3, the timing acquisition operation
does not work at all.
 improved in case of the sector-common frequency allocation due to the construction of the repeated
waveform.
Based on above discussion and simulation results, we suggest each synchronization signal is transmitted in a
manner of sector-common frequency allocation.
5. Synchronization Signal Transmission Considering Multi-antennas
According to desirable design criteria discussed in Chapter 2, we introduce an efficient transmit scheme for the
synchronization channel in this chapter in order to provide a channel estimation capability for each antenna. In
this chapter, we assume a 2x repeated synchronization channel structure. The introduced scheme can be also
applied to the general Nx repeated structures.
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IEEE C802.16m-08/478
Figure 8 shows the suggested CDD (Cyclic Delay Diversity) structure in the synchronization channel with the
predefined shifts corresponding to each antenna ports. In order to enable MSs to estimate MIMO channels, it is
desirable to have a shifted offset between antennas larger than a CP duration. It can be implemented by a phase
rotation in frequency domain as well as a circular shift in time domain.
copy
Ant 0
CP
A
A
a_0(0)
Circular shift
by δ
.....
a_0(N-1)
copy
Ant 1
CP
A
A
δ
Circular shift
by (N_tx-1)δ
.
.
.
Ant N_tx-1
copy
A
CP
A
(N_tx-1)δ
Figure 8 Example of Tx operation for the synchronization channel
Figure 9 shows the corresponding example of Rx operation to perform channel estimation for each antenna at an
MS.
1
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IEEE C802.16m-08/478
copy
CP
A
A
a_0(0)
.....
a_0(N-1)
+
copy
CP
(frequency domain)
(time domain)
r(0)
A
..........
R(0)
r(N-1)
..........
R(N-1)
A
2. perform DFT(FFT)
δ
+
DFT(FFT) window
3. IDFT(IFFT) after
multiplying by the
sequence for ant0
(R(k)*conj(A_0(k)))
(frequency domain)
1. received signal at MS
Circular shift
by (N_tx-1)δ
+
copy
(time domain)
A
CP
A
r'(0)
. . . . . . . . . . r'(N/2-1)r'(N/2)
..........
r'(N-1)
(N_tx-1)δ
...
Eg. window for estimating
channel for ant0
...
Impulse response of the
channel for antenna0
Impulse response of the
channel for antenna1
Impulse response of the
channel for antennaN_tx-1
Figure 9 Example of Rx operation for channel estimation at the synchronization channel
The diversity gain from the proposed scheme can be confirmed as seen in Figure 10 and Figure 11.
1
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0
CDD, shift offset=CP length, TU6, 3km/h, FO=3ppm
10
1Tx-2Rx,
2Tx-2Rx,
4Tx-2Rx,
1Tx-2Rx,
2Tx-2Rx,
4Tx-2Rx,
1Tx-2Rx,
2Tx-2Rx,
4Tx-2Rx,
Timing acquisition failure rate
-1
10
Nsector=1
Nsector=1
Nsector=1
Nsector=2
Nsector=2
Nsector=2
Nsector=4
Nsector=4
Nsector=4
-2
10
-3
10
-4
10
-12
-10
-8
-6
Iref/Ioc [dB]
-4
-2
0
Figure 10 CDD with shift offset of CP length in Sync channel, TU6 3km/h
1
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0
CDD, shift offset=CP length, TU6, 120km/h, FO=3ppm
10
1Tx-2Rx,
2Tx-2Rx,
4Tx-2Rx,
1Tx-2Rx,
2Tx-2Rx,
4Tx-2Rx,
1Tx-2Rx,
2Tx-2Rx,
4Tx-2Rx,
Timing acquisition failure rate
-1
10
Nsector=1
Nsector=1
Nsector=1
Nsector=2
Nsector=2
Nsector=2
Nsector=4
Nsector=4
Nsector=4
-2
10
-3
10
-4
10
-12
-10
-8
-6
Iref/Ioc [dB]
-4
-2
0
Figure 11 CDD with shift offset of CP length in Sync channel, TU6 120km/h
The proposed CDD scheme on Sync channel has following advantages;
 The synchronization channel can be transmitted to MSs in a transparent manner by adapting CDD.
 Multi-antenna diversity gain can be achieved in the synchronization signal transmission.
 The channel estimation from each antenna can be available. This can improve the BCH decoding
performance when the synchronization channel is time/frequency-coherently located to BCH.
6. Conclusion
In this contribution, we discussed several aspects on designing the IEEE 802.16m synchronization channel.
Based on the above discussions and analyses, we summarize our preferences on the synchronization channel as
follows;
 Auto-correlation based synchronization channel structure
 Sector-common frequency allocation in the synchronization channel
 CDD transmission with predefined antenna-specific shift values in which the differences between
arbitrary two shifts
1
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References
[1] IEEE 802.16m-08/003r1, “Draft IEEE 802.16m System Description Document”
[2] IEEE P802.16Rev2 D2, “DRAFT Standard for Local and metropolitan area networks - Part 16: Air Interface
for Broadband Wireless Access Systems,” April, 2008.
[3] Wang, Ottosson, “Cell Search in W-CDMA”, IEEE JSAC August 2000, pp. 1470-1482
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Text Proposal for IEEE802.16m SDD
============= Start of text proposal =================================================
11.x.x Synchronization channel
The synchronization channel is transmitted by one OFDMA symbol in order not only to facilitate
time/frequency synchronization and the detection of Cell ID information but also to support the channel
estimation for each transmit antenna. The time-domain waveform of each synchronization signal, which is
transmitted in a manner of sector-common frequency allocation, should have two times or more repetition in
terms of its amplitude. The CDD scheme in a synchronization channel should be used with antenna-specific
shift values. Each shift offset between two antennas should have larger duration than CP length.
============= End of text proposal =================================================
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IEEE C802.16m-08/478
Annex A Simulation Environments
The simulation parameters used in this paper are summarized in Table 2.
Table 2 Simulation parameters
Parameter
Explanations
Carrier frequency
2.5GHz
System bandwidth
10MHz
Sampling factor
28/25
Sampling frequency
11.2MHz
Subcarrier spacing
10.9375kHz
FFT size
1024
CP config.
1/16 CP (= 5.71us)
Number of used subcarriers
852 for Sync channel, 840 for data channel
Number of guard subcarriers
172 for Sync channel, 184 for data channel
Frame duration & Sync channel
periodicity
5ms
Tx
1, 2, 4
Rx
2
Number of antennas
Multi-antenna transmission
scheme
CDD with 5.71us shift offsets in case of 2Tx and 4Tx
Sector-specific
3x repetition
Sector-common
2x repetition
Sector-specific
Binary sequence defined in [2] for preamble
Sector-common
Binary random generated sequence
Sector-specific
8.0 [2]
Sector-common
8.0*284/426
Repetition factor
Sync channel sequence
Power boosting factor on Sync
channel compared to other data
channels
Modeling of other data channels
Randomly generated QPSK signals
Timing acquisition algorithm
Auto-correlation based
Channel
No fading, TU6
Mobility
3km/h, 120km/h
Number of sectors
1, 2, 3
Modeling of other sectors (cells)
AWGN
Referenced sector
Sector 0
Averaging duration
5ms
Number of sequences (cell IDs) in
Sync channel
114
Frequency offset
3ppm
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IEEE C802.16m-08/478
The criterion on successful timing detection in this simulation is illustrated in Figure 12.
1 OFDM symbol duration
CP
Range for successful
timing acquisition (±CP)
Figure 12 Criterion of successful timing acquisition for simulation
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