PLiFi: Hybrid WiFi-VLC Networking using PowerLines

Pengfei Hu Parth H. Pathak Aveek K. DasZhicheng Yang Prasant Mohapatra

University of California, Davis

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 1 / 20

Outline

1 Introduction

2 PLiFi

3 Preliminary Results

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Introduction

Outline

1 Introduction

2 PLiFi

3 Preliminary Results

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 3 / 20

Introduction

Background

Visible Light Communication (VLC)Unlicensed spectrum from 390THz to 800THz provides highachievable data rate.Reuse of existing lighting infrastructure for purpose ofcommunication make it energy efficient.Unable to penetrate wall means less interference and bettersecurity

Power Line Communication (PLC)Utilizing existing power line network for data communication.PLC devices increase 130 million by 2013 since the introduction fHomePlug AV2 standard in 2012.HomePlug AV2 achieves over 1 Gbps of PHY data rate.

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Introduction

Challenges

LED to Internet ConnectivityMost researcher focus on LED-to-receiver without consideringhow the LED connecting to Internet.

Internet

LED

0101...000

UplinkCurrent VLC is limited to broadcasting.Devices equipped with high power LED for communication notpractical.

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 5 / 20

Introduction

Challenges continued

Device MobilityUser mobility and device orientation changes can result inmisalignment between transmitter and receiver.Blockage between transmitter and receiver.

InterferenceCo-channel interference among multiple transmitters.Absence of technique to interconnect and synchronize forCoordinated Multi-Point transmission (CoMP)

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 6 / 20

PLiFi

Outline

1 Introduction

2 PLiFi

3 Preliminary Results

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 7 / 20

PLiFi

PLiFi

PLiFi architecture for augmenting existing WiFi networks.

Reuse power line as backboneEthernet-PLC modem asbridge between WiFi and VLCnetwork.PLC network connected toVLC through PLC-VLCmodem

Ethernet-PLC Modem

Power distribution

networkInternet

(a) Single WiFi AP case

LED

VLC APPLC-VLC Modem

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 8 / 20

PLiFi

PLiFi

Cost-effective way of conneting LEDs.WiFi channel serves as uplink and takes over transmission whenno VLC.Power line serves as backhaul for VLC coordinated transmissionScalability for complicated network

Aggregation switch Controller

InternetEthernet-PLC Modem

Power distribution

network

PLC-VLC Modem VLC AP

Ethernet

Power line

LED

(b) Enterprise networking case

WiFi AP

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 9 / 20

PLiFi

PLiFi Design

MAC DesignSending NACK via WiFi uplink for corrupted or lost frameRTS/CTS packets for collision avoidance transmission

Ethernet-PLC and PLC-VLC Modems

HomePlug AV2

Maximum 1.2Gbps

ZyXEL PLA5405 Beaglebone Black

PLC (OFDM) toVLC(On-Off-Keying)

20 MSPS

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 10 / 20

PLiFi

PLiFi Design

VLC Transmission SchemesIndividual Transmission: exclusive use of each LEDJoint Transmission: coordinated and synchronized transmissionamong multiple LEDs.

Tx/Rx LED Photodiode

Joint TransmissionIndividual Transmission

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Preliminary Results

Outline

1 Introduction

2 PLiFi

3 Preliminary Results

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 12 / 20

Preliminary Results

Power Line Network

SettingEthernet-PLC modem: ZyXEL PLA5405University building with an area of 1300 square meters.

400 - 500

300 - 400

200 - 300

100 - 200

50 - 100

10 - 50

0 - 10

(Mbps)

Server

Client

C1

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Preliminary Results

Visible Light Mobile Network

SettingLED: TCP RL10DR427K with 650 lumens.Ethernet-PLC modem: ZyXEL PLA5405VLC controller: Beaglebone Black linux board.WiFi router: Asus RT-AC68U with custom firmware

Power supply

BeagleBone

LEDWiFi router (controller)

PLC-Ethernet adapters

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 14 / 20

Preliminary Results

Tx and Rx

Luminous Path Loss(LL)

LL =(m + 1)A

2πD2 cosα cosm β (1)

Distance (D)

Transmitter LED

Receiver

Irradiation angle

Incident angle

Light sensor

AreaFOV

D: distance betweentransmitter and receiverα: incident angleβ: irradiation angle

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 15 / 20

Preliminary Results

Relative Positions of Tx and Rx

RSS drops sharply as the distance increasesRSS with variation in irradiation angle β following theoryRSS with variation in incident angle α dropping faster than theory.Because of field-of-view (FOV) of receiver

0.0001

0.001

0.01

0.1

1

0 0.5 1 1.5 2 2.5 3 3.5 4

Irradiation angle = 0o

Incident angle = 0o

Norm

aliz

ed R

SS

LED (Tx) to Sensor (Rx) Distance (meters)

ObservedTheoretical

(a)

0

0.2

0.4

0.6

0.8

1

0 10 20 30 40 50 60 70 80 90

Distance = 1m

Incident angle = 0o

Norm

aliz

ed R

SS

Irradiation angle (β)

ObservedTheoretical

(b)

0

0.2

0.4

0.6

0.8

1

0 10 20 30 40 50 60 70 80 90

Distance = 1 m

Irradiation angle = 0o

Norm

aliz

ed R

SS

Incident angle (α)

PD 1PD 2Theoretical

(c)

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Preliminary Results

Transmission Schemes

SINR measured at 16 locations (4ft .× 4ft grid)A as transmitter while B as interferer.

P1 P2 P4P3

P16P13

P5 P6 P7 P8

P14 P15

SINR (dB) JT (%)

11dB 10% 10dB 11% 7dB 25% 3dB 86%

11dB 9% 9dB 15% 6dB 29% 3dB 74%

7dB 11%

P12P11P10P9

9dB 13% 8dB 21% 4dB 45% 3dB 43%

8dB 21% 4dB 44% 2dB 61%

1ft 1ft 1ft

2.5ft 2.5ft

1ft

1ft

1ft

A B

SINR decreases sharply whenreceiver moves from A to BSINR increases significantlyunder joint transmission

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 17 / 20

Preliminary Results

Research in Progress

Extending PLiFi to combat RSS variation and SINR degradation.Design of integrated PLC-VLC modemHigh-speed LED front-end with COTS

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Preliminary Results

Questions?

Pengfei Hu, Parth H. Pathak, Aveek K. Das, Zhicheng Yang, Prasant Mohapatra (UC, Davis)PLiFi: Hybrid WiFi-VLC Networking using Power Lines VLCS 2016 19 / 20

Preliminary Results

Thank you!

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