Transcript IEEE C802.16m-09/2238r3

CoFIP Pilot Structure
Document Number: IEEE C80216m-09_2238r3
Date Submitted: 2009-11-17
Source:
Padmanabhan M S, Kiran Kuchi, J. Klutto Milleth, Sivakishore
CEWiT, India
Voice:
E-mail:
[email protected],
[email protected]
Venue: Comments
on P802.16m/D2 (15.3.5.4.1)
Base Contribution: None
Purpose: To discuss and adopt the proposed text in D3
To discuss in TGm for appropriate action. Notice:
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Collision Free Interlaced Pilots
(CoFIP)
Outline



In Jeju it was agreed that CoFIP will be used for CDR.
Details of CoFIP are TBD.
In this contribution details of CoFIP pilot structure are
given
In 2253, 2-stream pilot-on-data is proposed.



Performance of both methods compared
CoFIP is shown to be more than 2.0-2.5 dB better than
2-stream pilot-on-data using a low-complexity MMSE
receiver
Proposed text
Proposed CoFIP
P
0
0
P
0
0
0
P
0
0
P
0
0
0
P
0
0
0
0
P
0
P
0
P
0
0
0
P
0
P
0
0
0
0
P
0
P
0
0
P
Pilot pattern Set 0
0
0
0
P
0
0
P
Pilot pattern Set 1
P denotes pilot tone and 0 denotes null tone
P
0
0
P
Pilot pattern Set 2
0
P
0

Pilot structure proposed in S80216m-09_2253
Simulation setup 1
– 2Tx antenna – 2Rx antenna, one stream CDR transmission
– Channel: Modified Ped B, 30 km/h
– Thermal noise level is 30 dB below the power of the desired signal
– QPSK ½ CTC , eight 18x6 PRUs forms a channel coding block.
–
2D-MMSE channel estimation. All estimation done within a PRU
– Short PRBS pilot sequences (sequences with low cross-correlation) are
used.
– Interference profile: [0 0 -3 -4 -5 -7 -9 -12]
– Direct MMSE is used for demodulation
– Interference covariance is estimated from 1) pilot tones and null tones for
CoFIP 2) pilot tones for Interlaced pilot structure
– Interference pilot knowledge is NOT used in the 2D-MMSE channel
estimation. Additional channel est improvement feasible with using pilot
knowledge in CE (approx 1.0 dB gains shown previously)
6
CoFIP outperforms pilot-on-data by over 2.0 dB
Goodput = (1 – bler)*(1- pilot overhead)
CoFIP outperforms Pilot-on-Data in goodput
Simulation setup 2

Interference profile at 0 dB SIR [-4.7 -4.7 -4.7dB].

Direct and indirect MMSE are used for demodulation.

Thermal noise level is 10 dB below the power of one interferer.
CoFIP outperforms pilot-on-data by over 2.5 dB
Goodput = (1 – bler)*(1- pilot overhead)
CoFIP outperforms Pilot-on-Data in goodput
Conclusion



CoFIP outperforms pilot-on-data by over 2.0-2.5 dB

Knowledge of interference pilot sequence is NOT used in CoFIP receiver

With interference pilot knowledge CoFIP which uses pilot-on-pilot
collisions benefits

Pilot-on-data does not benefit from interferer pilot knowledge

The good put of CoFIP is much higher than pilot-on-data
CoFIP is suitable for CQI estimation in OL region
using always ON pilot in select sub frames
Pilot-on-Data does not ensure proper CQI estimation


It fails to provide proper CQI if data tones are not transmitted
in interfering cells
Adopt CoFIP in type-1 OL region
Proposed text
……………………..Start of Text……………………………………………………….
Section 15.3.5.4.1 page 305 line 39
Type-1 OL MIMO region shall use Collision Free Interlaced Pilot (CoFIP)
pattern.
Figure xxx shows the CoFIP pattern for AAI sub-frames consisting of 6
OFDM symbols. The index of the pilot pattern set used by a particular BS
with Cell_ID=k is denoted by pk. The index of the pilot pattern set is
determined by the Cell_ID according to the following equation: pk =
mod(k,3).
For AAI sub-frames consisting of 7 OFDM symbols, the first OFDM symbol
which contains pilot tones and null tones in each pilot pattern set shown in
Figure xxx is added as the 7th symbol
Figure yyy shows the pilot pattern set for AAI sub-frames consisting of 5
OFDM symbols
6 symbols
18 contiguous subcarriers
1
X
X
1
X
X
X
1
X
X
1
X
X
1
X
1
X
X
1
X
1
X
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1
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1
Pilot pattern set 0
X
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1
X
X
Pilot pattern set 1
X
X
X
1
X
1
1
1
X
X
X
X
X
X
1
X
1
1
X
Pilot pattern set 2
Figure xxx - The CoFIP Pattern for AAI sub frames with 6 OFDM symbols
X
5 symbols
18 contiguous subcarriers
1
X
X
X
X
1
X
1
X
X
X
1
X
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1
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1
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Pilot pattern set 0
1
X
X
X
1
X
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Pilot pattern set 1
X
1
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1
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1
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X
1
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1
X
X
Pilot pattern set 2
Figure yyy - The CoFIP Pattern for AAI sub frames with 5 OFDM symbols
……………………..End of Text……………………………………………………….