March 2016 doc.: IEEE 15-16-0254-00-007a Project: IEEE ... · LED lighting in the global market ......

doc.: IEEE 15-16-0254-00-007a

Submission

March 2016

Yiguang Wang, Nan Chi, Junwen Zhang, Fudan UniverisitySlide 1

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: High-speed VLC modulation formats and MIMO transmission

Date Submitted: March 2016

Source: Prof. Nan Chi, Dr. Junwen Zhang, Mr. Yiguang Wang Company: Fudan Univerisity

Address: Fu Dan University, 220 Handan Rd., Yangpu District, Shanghai

Voice: Tel: 0086-21-65642983, E-Mail: [email protected]; [email protected];

[email protected];

Abstract: In response to «Call for Proposals for OWC Channel Models» issued by 802.15.7r1, this

contribution presents the PHY technologies proposal of high-speed VLC modulation formats and MIMO

transmission.

Purpose: Call for Proposal Response

Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for

discussion and is not binding on the contributing individual(s) or organization(s). The material in this

document is subject to change in form and content after further study. The contributor(s) reserve(s) the right

to add, amend or withdraw material contained herein.

Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE

and may be made publicly available by P802.15.

doc.: IEEE 15-16-0254-00-007a

Submission Slide 2

High-speed VLC modulation formats and

MIMO transmission

March 2016

Yiguang Wang, Nan Chi, Junwen Zhang, Fudan Univerisity

doc.: IEEE 15-16-0254-00-007a

Submission Slide 3

Outlines

Background and Introduction

Scenario Targets

Description of Proposed Solutions

Some Experiment Results

Conclusions

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 4

Background

106

107 10

810

910

1010

1110

1210

1310

1410

1510

16 Hz

AM

radio

FM

radioTV Celluar

phone

Wireless

LAN

Infrared

lightUltraviolet

light

Visible

light

1THz1MHz 1GHz 3THz

Radio wave Light wave VLC

LED lighting in the global market

Expand the spectrum for the next generation of broadband communications

Combine lighting with communication, bringing unique advantages

By 2018, the semiconductor lighting penetration will reach 80%. With the popularity

of LED lighting process, VLC will be standing on the shoulders of giants.

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 5

Targets

• High-speed VLC MIMO transmission

• Data Rates Speed: ~Gbps

• Distance: 3m~5m

• Environment: indoor public space for multiple users

• Link: non-imaging MIMO, imaging MIMO

To provide a high-speed VLC free-space link for multi-user access.

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 6

Proposal Research Route

VLC channel coding for MIMO

STBC coding for MISO MRC based receiver diversity

VLC MIMO transmission modes

Non-imaging MIMO & time-multiplexed TS PDM transmission

High-speed VLC modulation formatsBit and power loading based adaptive OFDM SC-FDMA ACO-OFDM

MIMO Transmission Experiments

System Structure Results and Analysis

Imaging MIMO

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 7

TX： electronics：LED driving circuit，coding, modulation, Pre-equalization

optics：transmitter antenna (Multiple Input)

RX： optics：receiver antenna (Multiple Output)

electronics： signal processing (decoding, demodulation, equalization),

Physical Layer of VLC system

Visible light

transmission

LED

coding

modulation

Pre-equalizationO to E

TxModule

LED ModulationRx Module

AD

AD

Demodulator

Decoder

Data

BasebandQ

I

Phase

Signal processing

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 8

To achieve the high speed VLC

Modulation formats:

• Bit and power loading based adaptive OFDM

• Single-carrier FDMA (optional)

• Asymmetrically-clipped optical OFDM (optional)

MIMO transmission modes

• Non-imaging MIMO with time-multiplexed training symbols

• Imaging MIMO

• Polarization division multiplexing (PDM) transmission

Channel coding for MIMO

• Self-adaptive space-time block coding (STBC) for MISO

• Maximal ratio combining (MRC) based receiver diversity

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 9

Bit and power loading based adaptive OFDM modulation

M-QAM

Modulation

Serial to

Parallel

Power

allocation

Carrier

mappingIFFT Adding CP

Parallel

to Serial

Adaptive bit

allocation

Adaptive power

allocation

SNR

estimation

Before applying bit and power allocation, the SNR of the channel is

estimated through EVM method2

0,1

2

0,1

M

n nn

M

nn

S SEVM

S

2

1SNR

EVM

21( log )

N

kkB M

RN

Bit and power loading is used in adaptive OFDM signal

generation to maximum system capacity

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 10

Pre-qualizer Bias Tee

EA1

LE

D

Lens

TIA

LED

TX RX

PIN

Arbitrary

Waveform

Generator

Blue Filter

Oscilloscope

EA2

EA3

Output+

Output-

Channel1

Channel2

TIA+

-

DC supply

GND

AMP

DC supply

AMP

AMP

AWG710 54855A

X. Huang, et al, IEEE Photonics Journal, 2015


March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 11

0 50 100 150 200 250

0

10

20

30(a) SNR estimation (dB)

0 50 100 150 200 2500

5

(b) Bit allocation

0 50 100 150 200 2500

5

(c) Power allocation

Subcarrier index

X. Huang, et al, IEEE Photonics Journal, 2015


March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 12

Single carrier modulation (optional):

Single-carrier frequency division multiple access (SC-FDMA)

SC-FDMA Modulation

Seri

al t

o P

aral

lel

N-p

oin

t ID

FT

Ad

d C

P

Par

alle

l to

Se

rial

Car

rie

r m

app

ing

SC-FDMA Demodulation

M-Q

AM

Map

pin

g

M-p

oin

t D

FTM

-po

int

DFT

Re

mo

ve C

P

N-p

oin

t D

FT

Par

alle

l to

Se

rial

Seri

al t

o P

aral

lel

M-p

oin

t ID

FTM

-po

int

IDFT

M-Q

AM

De

map

pin

g

SC-FDMA can be an optional choice for uplink, due to its advantage to

provide low PAPR for the transmit waveform;

SC-FDMA divides the transmission bandwidth into multiple parallel

subcarriers, which adds a DFT block before the subcarrier mapping

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 13

Transform domain processing (TDP) based channel

estimation method for SC-FDMA

Transform domain processing

(TDP) can be used for channel

estimation:

improve the accuracy of

channel estimation

reduce the length of

overhead

H(k) is transformed to HT(m) by employing another DFT. HT(m) is in

transform domain and expressed as

1

0

( ) ( ( )) exp( 2 / )N

T

k

H m H k j mk N

L. Tao, et al, Optics Express, 2013

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 14

Unipolar modulation (optional):

Asymmetrically-Clipped Optical OFDM (ACO-OFDM)

M-QAM

Modulation

Serial to

Parallel

Carrier

mappingIFFT Adding CP

Parallel

to Serial

Asymmetrical

clipping

Y. Wang, et al, Photonics Research, 2014

ACO-OFDM can be used as a unipolar modulation scheme to further

improve the power efficiency.

The time domain signal is made unipolar by simply clipping the negative

part at the zero level.

Only odd subcarriers are modulated by signals, and all of the clipping

distortion products fall on the vacant even subcarriers.

……… …

… …

… …

……… …

… …

… …

ACO-OFDM Signal

DCO-OFDM Signal Beating Noise

Beating Noise

Output

Output

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission

March, 2016

Slide 15 Yiguang Wang, Nan Chi, Junwen Zhang, Fudan Univerisity

Unipolar modulation (optional):

Asymmetrically-Clipped Optical OFDM (ACO-OFDM)

10 20 30 40 50 60

1E-3

0.01

BE

R

Distance (cm)

ACO-OFDM, 100MHz BW

DCO-OFDM, 100MHz BW

DCO-OFDM, 50MHz BW

AWG

TransmitterLens

Receiver

OSC

12 14 16 18 20

1E-3

0.01

BE

R

Electrical Input Power (dBm)

ACO-OFDM, Red Chip

DCO-OFDM, Red Chip (b)

doc.: IEEE 15-16-0254-00-007a

Submission Slide 16

MIMO transmission modes: Non-imaging MIMO

1 11 12 1 1

2 21 22 2 2

Y H H X N

Y H H X N

Light from each of the LED arrays is received by all the separate receivers,

but with different strengths

Y. Wang, et al, IEEE Journal of Lightwave Technology, 2014

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 17

Time-multiplexed training symbols for non-imaging

MIMO de-multiplexing

The time-multiplexed TS based frequency domain equalization can be used for

MIMO channel estimation and de-multiplexing

1

1 2

2

0,

0

TST T

TS

11 12 11 1 12 2

21 22 21 1 22 2

/ /

TS /

H H Y TS Y TSH

H H Y Y TS

1 22 1 12 2 22 11 12 21

2 11 2 21 1 22 11 12 21

( ) / ( )

( ) / ( )

X H Y H Y H H H H

X H Y H Y H H H H

Zero forcing

Y. Wang, et al, IEEE Journal of Lightwave Technology, 2014

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission

March, 2016

Slide 18

MIMO transmission modes: Non-imaging MIMO


doc.: IEEE 15-16-0254-00-007a

Submission Slide 19

MIMO transmission modes: Imaging MIMO

Imaging MIMO requires each LED array imaging onto a detector array, and

the light propagates directly to the corresponding detector

11 11 1

22 22 2

0 / 0

0 0 /

H Y TSH

H Y TS

Channel crosstalk can be neglected, and the channel matrix can be simplified

Y. Wang, et al, Chinese Optics Letters, 2014

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission

March, 2016

Slide 20Yiguang Wang, Nan Chi, Junwen Zhang, Fudan Univerisity

MIMO transmission modes: Imaging MIMO

doc.: IEEE 15-16-0254-00-007a

Submission Slide 21

Polarization division multiplexing (PDM) transmission

Y. Wang, et al, Optics Letters, 2014

The received optical intensity can be expressed as

2 2

1 1 11 12 1

2 22 2 221 22

cos cos1

2 cos cos

Y I IH N N

Y I I

As the lights emitting from incoherent LEDs are natural lights, they can be

decomposed as two orthogonal bases of x polarization and y polarization by

polarizers.

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission

March, 2016

Slide 22Yiguang Wang, Nan Chi, Junwen Zhang, Fudan Univerisity

Polarization division multiplexing (PDM) transmission

doc.: IEEE 15-16-0254-00-007a

Submission Slide 23

Channel coding for MIMO:

Self-adaptive space-time block coding (STBC) for MISO

STBC technique can easily provide the diversity at

receiver for MISO VLC transmission

Alamouti’s STBC scheme is employed to encode

the data with two transmit LEDs and one

receiver. Space-time encoding as:

1 2

* *

2 1

c c

c c

1 1 2 11

* * * *22 2 1 2

r h h cr Hc n

cr h h

H H Hr H r H Hc H n

the decoded signal can be obtained as

J. Shi, et al, IEEE MOTL, 2015

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 24


Self-adaptive space-time block coding (STBC) for MISO

J. Shi, et al, OFC, 2016

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission 25

Σ

1r 2r 3r Mr

ith branch SNR:2 /i i ir N

Combiner output

SNR:

1 2 3 M

In receiver diversity, the outputs of

multiple receivers are combined which is

a weighted sum of the different

branches

2

21

2

1

M

i ii

M

tot i ii

rr

N N

The goal of MRC is to find the weight to maximize the output SNR

According to the Schwarz inequality: the maximum SNR of the combiner

output is the sum of SNRs in each branch:

2

1 1/

M M

i i ii ir N


Maximal ratio combining (MRC) based receiver diversity

J. Li, et al, Optical Engineering, 2015

March 2016


doc.: IEEE 15-16-0254-00-007a

Submission Slide 26

Conclusion In this contribution, we propose several general technique considerations

for high-speed VLC modulation formats and MIMO transmission.

Modulation formats:

• Bit and power loading based adaptive OFDM

• Single-carrier FDMA (optional)

• Asymmetrically-clipped optical OFDM (optional)

MIMO transmission modes

• Non-imaging MIMO with time-multiplexed training symbols

• Imaging MIMO

• Polarization division multiplexing (PDM) transmission

Channel coding for MIMO

• Self-adaptive space-time block coding (STBC) for MISO

• Maximal ratio combining (MRC) based receiver diversity

March 2016


March 2016 doc.: IEEE 15-16-0254-00-007a Project: IEEE ... · LED lighting in the global market ......

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