Iterative receiver architectures for MIMO HSDPA Date 03/11/04 R. - - PowerPoint PPT Presentation

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France Telecom Research & Development

Iterative receiver architectures for MIMO HSDPA

Date 03/11/04

• R. Visoz, A.O. Berthet

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Iterative receiver architectures for MIMO HSDPA

s Why?

QDisappointing results for MIMO HSDPA performance under a non

iterative receiver assumption, at least for 2x2 configuration

QFrom an information theory point of view, only spatial multiplexing can

• ffer a significant gain in spectral efficiency (code re-use)

QSpatial multiplexing adds, on top of Multi-User Interference (MUI) and

Inter-Chip Interference (ICI), Multiple Antenna Interference (MAI)

QAs a result, the spectral efficiency of MIMO HSDPA relies on efficient

receiver architectures that can deal with MAI+ICI+MUI

QThe most efficient receivers combine MIMO and Turbo principle = Turbo-

MUD

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Spatial MCS design

s Our spatial Modulation and Coding Schemes

(MCSs) are built from a well-known potentially capacity achieving transmission scheme : ST-BICM with Linear Precoding

s Overloaded linear precoding may introduce

further flexibility in spatial-MCS design

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Spatial MCS design

s ST-BICM-LP

Mapper Mapper Mapper Mapper NT × KT Spreading Matrix W N × K Spreading Matrix W(1) N × K Spreading Matrix W(T)

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n d1,1

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n d1

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n dT,1

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n dT

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n dT,K

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n

1,1

s

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n s1

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n

1,K

s

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n

T,1

s

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n sT

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n

T,K

s

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n

1,1

x

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n x1

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n

1,N

x

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n

T,1

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n xT

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n

T,N

x

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l

1

x

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l x

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l

T

x Outer code

Π

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n d1,K

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Receiver architecture (example)

− MAI+ISI treatment ˆ X Y

• Y

− Z

• MUI

regeneration SISO mapper (log-domain) S MUI treatment SISO demapping (log-domain) ˆ S ˆ Z S S MAI+ISI regeneration spreading Z X from the decoder from the decoder to the decoder

MMSE criterion is spread in the receiver architecture

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Simulation results

s All simulations are based on

Qrate-1/2 PCCC, 4608 uncoded block size QGray labeling QSF =16 Q2x2 MIMO channel QVeh A channel profile Qperfect channel estimation QMMSE chip-equalizer with sliding window length 21 QNo iteration within the turbo-code (AdHoc scheduling)

s For all simulations 2 benchmarks:

QMFB => Genie Aided receiver 5 turbo-code iteration QOutage Capacity => probability that the channel capacity is

below the transmission rate

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simulations results

s QPSK, 100% load per antenna, 2bpcu

1 ,0E-04 1 ,0E-03 1 ,0E-02 1 ,0E-01 1 ,0E+00

• 2

2 4 6

Eb/No (dB) BLER

• utage

MFB (5 iter) MMSE it0 MMSE it1 MMSE it5 MMSE it14

1.3 dB

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simulations results

s 16-QAM, 100% load, 4bpcu

1 ,0E-03 1 ,0E-02 1 ,0E-01 1 ,0E+00 2 4 6 8 1

Eb/No (dB) BLER

• utage

MFB (5 iter) MMSE it0 MMSE it1 MMSE it5 MMSE it14

4 dB

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simulation results

s 64-QAM, 100% load, 6pbcu

1 ,0E-03 1 ,0E-02 1 ,0E-01 1 ,0E+00 2 4 6 8 1 1 2 1 4

Eb/No (dB) BLER

• utage

MFB (5 iter) MMSE it0 MMSE it1 MMSE it5 MMSE it14

6dB

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Conclusion

s Iterative receiver architectures are needed to

extract the spatial multiplexing gain brought by MIMO = Key feature for the UMTS evolution

s Iterative receiver architectures enable the use of

power and spectrally efficient spatial-MCS = ST- BICM-LP

s Iterative receiver architectures should be

investigated within the standardization process since they condition the choice of the transmission schemes (SI?)