© 2013

Wi-Fi Maritime Communications Using TV White SpacesMsC Dissertation

Luciano Jorge Silva Santosee08251@fe.up.pt

Supervisor Manuel RicardoCo-supervisor Rui Campos

© 2013 2Wi-Fi Maritime Communications Using TV White Spaces

• Introduction

• Current Maritime Communications

• Context

• Motivation

• Previous Work

• Maritime Environment

• Outdoor long range link TVWS

• Propagation models

Contents

• On going Work

• Theoretical Results

• Hardware

• Scenario

• Experiments

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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

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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

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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

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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)

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

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Outdoor long distance link with TVWS band

• System configuration

• Equipment

• Mikrotik RB433 router boards

• Ubiquiti XR7 700 MHz cards

• 14 dBi Yagi Directional antennas

• Configurations

• Tx power: 28 dBm

• Channel width 5 Mhz

• 802.11b

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18 m 50 m7 m

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

Variation of RSSI between node 1 and 2

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Scenario

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

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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

• 2x Omni Directional Antenna

• 700-2700 MHz

• 3 dBi gain

• GPS USB

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Omni Directional Antenna

Ubiquiti XR7 card Alix 3D3

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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

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Theoretical Results

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• 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

10 490 970 14501930241028903370385043304810529057706250673072107690817086500

20

40

60

80

100

120

1402-Ray Path Loss Model 760 MHz

Distance (m)

Path

loss (

dB

)

• Max Path loss: 118.16 dB

• Max Distance: 7530 m

• Fresnel Zone: 27.25 m