Mobility at CERN

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Sebastien.Ceuterickx@cern.ch

IT/Communication Systems

HEPiX Fall 2013

Agenda• Evolution of Wi-Fi at CERN• BYOD impact• Special Wi-Fi deployments• Eduroam@CERN

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Development of the CERN Wi-Fi

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4,000 simultaneous users

1,400 Access points

280,000m2 covered

7,000 unique devices per day

7 Gbps of traffic

Early 2007

x 6 Devices in 6 years

Wi-Fi is complex

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The challenges:

- client related issues

- infrastructure issues:- deployment challenges- sources of interference

- (high) density issues

- a combination of all factors

- expected QoS from the user’s point of view

Challenges: client issues

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Challenges: a diverse infrastructure

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Challenges: A large and dynamic environment

• 600,000m2 indoor area (+20% in 6 years)• 650 surface buildings (+15% in 6 years)• 2,100,000m2 outside area (stable)

• New experiments• Building refurbishment

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Challenges: intensive usage• From an extension of the structured cabling

to fundamental service

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The primary connection for an increasing number of devices

How do we address this?

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Optimizing RF spectrum!

• Migration from 802.11bg to 802.11n 5GHz• Up to 240Mbps half-duplex shared

• From 200m2 per AP to 120m2 (-40% )• Increase the density of APs

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Avoid the 2.4GHz Band where possible

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Turning ON is not enough• Band steering • Load balancing • Auto-channel assignment• Auto-power tuning

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Might not work out of the box

RF planning and site survey still required

Wi-Fi tuning necessary

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Automation for scalability

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Automated RF configuration

Simplify

Save resources

Increase reliability

Data Base

Network Management System

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Integrated within global NMS

Control, act and support

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Efficient monitoring and analysis system deployed

Remote operation

Proactive optimization

Efficient end-user support

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Ban them ??

BYOD: The impact

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802.11n compliant BUT…

1 spatial stream (75Mbps max)Reduced Wi-Fi performance

Ban (very) poor connectivityOptimize RF planningIncrease AP density

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Special deployments

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Conference rooms

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• Efficient RF planning for• Minimizing interference• Optimizing load sharing

Capacity is the key concern.

• Reduce Tx Power• Ban slow stations & low data rates• Enable band steering and airtime fairness• Use external antennas

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Underground caverns

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• Efficient RF planning for• Minimizing co-channel interference• Maximizing coverage

Coverage is the key concern.

• Disable band steering• Enable RTS/CTS• Use external antennas and power dividers• Use a leaky feeder

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eduroam@CERN

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Travelling?Take Internet access with you!

• A secure international roaming service• Based on a federation of RADIUS servers

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Home Institute

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How do we deploy it?• freeRADIUS• certificate based for CERN user (EAP-TLS )

• No additional hardware• Fully automated

• Pilot version running• end 2013 : 80% of the infrastructure

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Conclusion• WLAN at CERN will continue to grow.

• Wi-Fi has became a (highly) popular and fundamental service which requires a significant investment to work properly in a professional environment.

• 802.11ac will bring new opportunities

--- and new challenges.

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Thank you!

Question

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Future

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802.11ac• 5 GHz only• New higher rate modulation • Will be release in 2 “waves”

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Wave 1 (2013) Wave 2 (2015)

Up to 80MHz Up to 160MHz

Up to 3 spatial streams Up to 4 spatial streams

Single-User MIMO Multi-User MIMO

Up to 650Mbps Up to 1732Mbps

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New opportunities……new challenges

• Higher throughput• Better performance at the same range

• Impact on infrastructure ?• Impact on RF planning ?

• Higher rate only at short range • (-55dBm = same room)

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