performance comparison of cdm and fdm for sounding channel of 802.16m awd ieee 802.16 presentation...

Performance Comparison of CDM and FDM for Sounding Channel of 802.16m AWD

IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number:

IEEE C80216m-0850Date Submitted:

2009-04-27Source: KeunChul Hwang, Jing Li, Inseok Hwang, Soon Young Yoon [email protected] Samsung Electronics

Venue: IEEE 802.16m Session#61, Cairo, Egypt

Base Contributions:N/A

Re: Call for Contributions on Project 802.16m Amendment Working Document (AWD) Content Purpose: To discuss and adopt in TGmNotice:

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.

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http://standards.ieee.org/guides/bylaws/sect6-7.html#Slide%206

http://standards.ieee.org/guides/bylaws/sect6-7.html#Slide%206

Motivation

• There are Two Options for sounding multiplexing in the current UL CTRL

AWD text (80216m-09_0010r1a), – Option 1: decimation separation (FDM) or cyclic shift separation (CDM)

– Option 2: decimation separation (FDM)

• Link-level and system-level simulation results are provided to compare the performance of decimation separation (FDM) and cyclic shift separation (CDM).

• Performance of CDM and FDM depends on the number of MS per sector, the channel estimation scheme and interference level

• Option 1 is needed for 16m Sounding due to different performance of CDM and FDM

Summary

Preferred

Scheme

K=1 MS/sector K=6 MS/sector

LS LS+MMSE LS LS+MMSE

Noise limited CDM CDMFDM CDM FDM

Interference limited

CDM CDM CDM CDMFDM

• Performance at low SINR ( less than 0dB) should be paid more attention

• The following simulations focus on performance at SINR [-10, 10]dB

UL SINR distribution (57 sectors)

-30 -25 -20 -15 -10 -5 0 5 10 150

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SINR (dB)

CD

F

UL SINR distribution

6MS/sctr1 MS/sctr

98% of MSs have SIR less than 0dB

55% of MSs have SIR less than 0dB

Simulation parameters

OFDM parameters 10 MHz (1024 subcarriers, 864 used subcarriers)

Sounding sequence

CDM cyclic shift (P): 6, 18 cyclic shift index: 0,1,2,…,K for both serving and interference cell

FDM decimation value (D): 6, 18 subcarrier offset (g=0,1…D) for both serving and interference cell

Loading size 72 tones (one band)

# of sectors1 for noise limited case2 for interference limited case

# of MS per sector (K) 1 or 6

Channel model ITU modified Ped.-B (3km/h, 2.4GHz)

Channel estimation -LS -LS+MMSE: perform LS over each P tones, then MMSE over 18 tones

Performance Metric MSE

LLS results (K=1,P=D=18)

• In noise limited case, using LS+MMSE, CDM and FDM have similar performance

• In the other cases, CDM performs better than FDM

-10 -8 -6 -4 -2 0 2 4 6 8 10-18

-16

-14

-12

-10

-8

-6

-4

-2

0

SNR (dB)

MS

E (

dB

)

Noise limited, K=1, P=D=18

CDM LSFDM LSCDM LS+MMSEFDM LS+MMSE

-10 -8 -6 -4 -2 0 2 4 6 8 10-20

-15

-10

-5

0

5

10

SIR (dB)

MS

E (

dB

)

2 sectors, K=1, P=D=18

CDM LS+MMSEFDM LS+MMSECDM LSFDM LS


• In noise limited case, using LS+MMSE, CDM and FDM have similar performance

• In the other cases, CDM performs better than FDM

-10 -8 -6 -4 -2 0 2 4 6 8 10-20

-15

-10

-5

0

5

SNR (dB)

MS

E (

dB

)



-10 -8 -6 -4 -2 0 2 4 6 8 10-25

-20

-15

-10

-5

0

5

10

SIR (dB)

MS

E (

dB

)




• In noise limited case, using LS+MMSE, FDM performs better• In the other cases, CDM performs better than FDM

-10 -8 -6 -4 -2 0 2 4 6 8 10-20

-15

-10

-5

0

SIR (dB)

MS

E (

cB)



-10 -8 -6 -4 -2 0 2 4 6 8 10-18

-16

-14

-12

-10

-8

-6

-4

-2

0

SNR (dB)

MS

E (

dB

)




• CDM and FDM have similar performance when P=D=6 and K=6

-10 -8 -6 -4 -2 0 2 4 6 8 10-20

-15

-10

-5

0

5

SIR (dB)

MS

E (

dB

)

2sectors, K=6, P=D=6


-10 -8 -6 -4 -2 0 2 4 6 8 10-20

-15

-10

-5

0

5

SNR (dB)

MS

E (

dB

)



SLS results (P=D=6)

• SLS results (57 sectors) are provided with LS+MMSE channel estimation

• CDM is obviously better than FDM when K=1/Sector, and CDM is slightly better than FDM when K=6/Secoter

-10 -5 0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SINR (dB)

CD

F

P=D=6

CDM K=1FDM K=1CDM K=6FDM K=6

Proposed Remedy

• Modify the text in lines 65, page 118 (section 15.3.9.2.3.2. in 80216m-09_0010r1a)

15.3.9.2.3.2 Multiplexing for multi-antenna and multi-AMS

AMS and multiple antennas per AMS can be multiplexed through [Option 1: decimation separation or cyclic shift separation][Option2: decimation separation] in each sounding allocation. Also, in case of multiple UL subframes for sounding, time division separation can be applied by assigning different AMS to different UL subframe. For cyclic shift separation each AMS occupies all subcarriers within sounding allocation and uses the different sounding waveform [Editor's note: remove this sentence if Option 2 will be adopted]. For frequency decimation separation each AMS uses decimated subcarrier subset from the sounding allocation set with different frequency offset. For antenna switching capable AMS, ABS can command the AMS to switch the physical transmit antenna(s) for sounding transmission. The details for supporting antenna switching on sounding is TBD.

Appendix. Channel estimation methods

• System model

• LS

• LS+MMSE

1H HLSh W W W y

1 2

1 2

[ ] [0], [1],... [ 1] is the sounding seq. of user

[ ] is the freq. channel response of userwhere K is No. of users/sector

denotes white noise

T

K k k k k

TK k

y h n

s s s s s s s P k

h h h h h k

n

W

W

2 1( ) Hhp pp hpBias R R I R

2 11( )

( )hp pp LSh R R I h

diag Bias

Number of OFDMA symbols

Loa

din

g si

ze (

one

ba

nd)

hLS1

1

2

:

P

1

2

:

P

1

2

:

P

1

2

:

P

hLS2

hLS3

hLS4

MMSE

CDM

Number of OFDMA symbols

Lo

ad

ing

siz

e (

on

e b

an

d)

hLS1

1

2

:

D

1

2

:

D

1

2

:

D

1

2

:

D

hLS2

hLS3

hLS4

MMSE

FDM

Appendix. Impact of power difference

• Power difference has little impact on MSE performance of both FDM and CDM

• Simulation condition– Power difference between center and edge users : 10dB

– Relative power difference at SNR = -10, -5, 0 (low geometry)

• [desired user#0, interf#1, interf#2,…interf#5] = [0dB 0dB 0dB 10dB 10dB 10dB]

– Relative power difference at SNR = 5, 10 (high geometry)

• [desired user#0, interf#1, interf#2,…interf#5] = [0dB 0dB 0dB -10dB -10dB -10dB]

-10 -5 0 5 10 15 20-12

-10

-8

-6

-4

-2

0Noise limited, P=D=18

SNR (dB)

MS

E (

dB

)

CDM LS wo powdiffFDM LS wo powdiffCDM LS+MMSE wo powdiffFDM LS+MMSE wo powdiffCDM LS w/ powdiffFDM LS w/ powdiffCDM LS+MMSE w/ powdiffFDM LS+MMSE w/ powdiff

performance comparison of cdm and fdm for sounding channel of 802.16m awd ieee 802.16 presentation...

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