Wireless CCTV network for Transports Quebec in Gatineau TPF TM ITS... · balloons used on one end...

Wireless CCTV network for Transports Quebec in Gatineau

Simon Béliveau

Team leader, Telecommunications

ITS and Telecommunications

Canada East

June 12th, 2012

Scope of presentation Highlight the viability of license free wireless networks for ITS applications Highlight sensitive design areas

Project description

General description

• Goal is to increase safety and improve response in case of emergency

– Roadside video surveillance

– Telecommunications network

• Challenges

– Densely populated area

– No available underground conduit infrastructures

– Short term needs

June 12th, 2012 Wireless CCTV network for

Transports Quebec in Gatineau

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Video surveillance network

• 20 cameras throughout the Gatineau region

• IP based video signals (H.264 format)

• Completely wireless telecommunications network



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Traffic management center

• Traffic management center

– 6 monitor display wall

– 4 user stations

– Meeting room console and monitor

– Remote viewing capability through VPN connection



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Telecommunications

• Point to point radio communications

– Better viewing those links as complex rather than simple

– Many details often go unnoticed until problem arises

• Cost effective and very quick deployment

• Up to 50 Mbps per link



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Wireless telecom network

Two loops add redundancy



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• Ethernet based Spanning Tree Protocol (SPT)

– Careful design allows load balancing over all nodes

Antennas

• Two types of antennas used – Default planar

– Higher gain parabolic

• Reason for higher gain antennas

– Not for gain, but for reduced side lobes



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Antenna polar patterns

• Typical Planar antenna 1 sq. foot

• Typical 2 feet parabolic antenna



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• Parabolic antenna has reduced side lobes compared to planar antenna

License free radio bands

• Network is based on the 5 GHz UNII bands

– Unlicensed National Information Infrastructure (U-NII)

– 20 non-overlapping channels to choose from

• Interference

– A risk that must be managed

– Good understanding of limitations is important

– Careful design reduces risk considerably



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Wireless network design strategy

Standard design procedure used as foundation

• Topographical analysis



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Point to point design

• Line of sight and link budget analysis

– Important to know speeds vs. receive power



Page 15

Field survey

• Field survey

– 4 feet diameter helium balloons used on one end

– Aerial lift trucks used on other end

• Performed initial spectral analysis

– Not representative but helpful



Page 16

Design specifics



Page 18

Hub site synchronization (HSS)

• HSS syncs. all RX and TX time slots on a single site

– Improves sensitivity of radios collocated on same pole

• Only one side of a link can use this feature (master-slave configuration)

– Careful selection of hubs optimizes benefits

Automatic frequency selection (AFS)

• 20 channels to choose from in the 5 GHz U-NII band

• Automatic Frequency Selection (AFS)

– Automatically transfers to a clean channel when needed



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AFS WARNING:

• AFS creates a risk of auto-interference in such a dense network!

– Avoided by designing 4 distinct frequency groups

– Each radio allowed to operate on only one group



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Lakes and rivers

• Clear line of sight over lake

– Looks like a great path

– Right?



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WARNING: Risk of multipath fading!

• Lake creates a risk of undesired reflections

– Unpredictable decrease of Carrier to Interference and noise ratio (CINR) may result



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Ice and snow

• ICE doesn’t conduct electricity, liquid water does!

– Ice formation changes antenna pattern with moderate power losses

– Melting ice and snow are more damageable

• Radomes help keep water away



Page 24

Rain

• Rain affects microwave links

– Right?

• Crane and ITU-R rain fade models show not a problem for 5 GHz bands

• No need to worry about rain under 10 GHz

– Unless very long links are involved (~100 Km)

Other things to keep an eye on

• Think about power attenuators if link is very short

– Better: Find modems with automatic power attenuation capability

• Careful deployment supervision

– Antennas aligned on secondary lobes is a reality

– Make sure the RX power matches theoretical values (no more than 6 dB)

• Provide a good Network Management System (NMS) for continuous network logging

• If possible, make a multi-day spectrum survey before powering all radios



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Final words

• Design has been done in close interaction with the MTQ team in Gatineau, thanks to them for the excellent support.

• Project has been prized by the Association of Consulting Engineers of Quebec (AICQ), in the telecommunications category.



Page 26

Thanks, merci.

[email protected]

Wireless CCTV network for Transports Quebec in Gatineau TPF TM ITS... · balloons used on one end...

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