Slide 1

Wi-Fi Maritime
Communications Using TV
White Spaces
MsC Dissertation

Luciano Jorge Silva Santos
[email protected]

Supervisor Manuel Ricardo
Co-supervisor Rui Campos
© 2013


Slide 2

Contents
• Introduction

• On going Work

•

Current Maritime Communications

•

Theoretical Results

•

Context

•

Hardware

•

Motivation

•

Scenario

•

Experiments

• Previous Work

© 2013

•

Maritime Environment

•

Outdoor long range link TVWS

•

Propagation models

Wi-Fi Maritime Communications Using TV White Spaces

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Slide 3

Current Maritime Communications
• Most common used Technologies
• HF and VHF bands
• Satellite connections
• Low bandwidth and expensive

• 2G/3G (near the shore)

• Motivation
• A need for low cost communications
• A need for high bandwidth and speed networks
• Real time data transfers
• Live VoIP and video surveillance streaming

• Data exchange between fishing boats

© 2013

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Slide 4

Motivation

• Not viable to install base stations in the high sea
• Connection range up to 100 Km from the shore
• Transition to digital television
• 700 MHz band released by analogic television
• Longer transmission ranges
• Better propagation characteristics in comparison with 2.4 GHz and 5.8 GHz

• No current tests done with this band in maritime environment

© 2013

Wi-Fi Maritime Communications Using TV White Spaces

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Slide 5

Maritime Environment
• Completely different from land environment
• Difficult to predict maritime state
•

Frequency propagation over water

•

Surface multipath reflection

•

Wave occlusion

•

Blockage RF signal by near boats

•

Boat rocking motion

•

Continuous changes in the antenna
orientation and height

• These factors provokes
•

Unstable connection

•

Strongly affects signal strength

•

Long delays

•

Increase PER

© 2013

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Slide 6

Propagation model for maritime communications
•

•

Proposed 2 Ray Path Loss model
•

L = Path Loss dB

•

ht = Transmitter antenna height

•

hr = Receiver antenna Height

•

d= Distance (m)

•

λ = Wavelength

Signal reflection on the sea
surface (two ray)

© 2013

ht=hr=18m F=2,4 GHz

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Slide 7

Outdoor long distance link with TVWS band

•

System configuration
•

•

Equipment
•

Mikrotik RB433 router boards

•

Ubiquiti XR7 700 MHz cards

•

14 dBi Yagi Directional antennas

7m

18 m

50 m

Variation of RSSI between node 1 and 2

Configurations
•

Tx power: 28 dBm

•

Channel width 5 Mhz

•

802.11b

Node
1 to 2

Node
1 to 3

Node
2 to 1

Node
2 to 3

Node
3 to 1

Node
3 to 2

1.62
Mbps

1.8
Mbps

1.65
Mbps

0.67
Mbps

1.63
Mbps

0.65
Mbps

© 2013

Wi-Fi Maritime Communications Using TV White Spaces

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Slide 8

Scenario

• ANACOM Restrictions:
 Max Tx Power: 28 dBm
 Channel Width: 5 MHz
 Frequencies between: 770-780 MHz

© 2013

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Slide 9

Hardware
• Hardware
• 2x Alix 3D3 Pc engine
• 2x Flash compact cards

• 2x Ubiquiti XR7
• Proprietary 700MHz, based on 802.11g OFDM
• TX Channel Width Support 5MHz / 10MHz / 20MHz
• Outdoor range up to 50 Km

Omni Directional Antenna

• 2x Omni Directional Antenna
• 700-2700 MHz

• 3 dBi gain

• GPS USB

© 2013

Ubiquiti XR7 card

Wi-Fi Maritime Communications Using TV White Spaces

Alix 3D3

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Slide 10

Experiments
• Analyse the performance of the 700 MHz link in maritime
environment with the following parameters:
• Range – Average distance possible to establish a connection between
the land station and the boat
• Connection throughput – Average bandwidth for different ranges
between the land station and the boat.
• Packet delay and Packet loss – Round Trip Time and the percentage
of packets loss for different ranges
• Jitters - Variation of time between arriving packets
• RSSI throughput – Received Signal Strength in dB

• TCP and UDP tests
• Analyse the results with meteorological conditions

© 2013

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Slide 11

Theoretical Results
Considering following
parameters:
•

•

Transmitted:
•

Tx Power: 30 dBm

•

Antenna Height: 20m

•

Antenna gain: 3 dBi

•

Attenuation: 0.94 dB

Received:
•

Min Power: -88 dBm

•

Antenna Height: 5m

•

Antenna gain: 3 dBi

•

Attenuation: 0.94 dB

Tolerance: 6 dB

140
120
100
80
60
40

20
0

10
250
490
730
970
1210
1450
1690
1930
2170
2410
2650
2890
3130
3370
3610
3850
4090
4330
4570
4810
5050
5290
5530
5770
6010
6250
6490
6730
6970
7210
7450
7690
7930
8170
8410
8650

•

2-Ray Path Loss Model 760 MHz

Pathloss (dB)

•

•

Max Path loss: 118.16 dB

•

Max Distance: 7530 m

•

Fresnel Zone: 27.25 m

© 2013

Distance (m)

Wi-Fi Maritime Communications Using TV White Spaces

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