3/4/2009 .

Cabling for 802.11n

Scott D. ThompsonPresident,

Oberon, Inc.

Cabling for 802.11n

Scott D. ThompsonPresident,

Oberon, Inc.

3/4/2009 .

IEEE 802.11n DEFINITIONIEEE 802.11n DEFINITION

• ““n” is a proposed amendment to the IEEE 802.11 Standardn” is a proposed amendment to the IEEE 802.11 Standard

• Uses advanced signal processing (Multiple Input/Multiple Uses advanced signal processing (Multiple Input/Multiple Output and beamforming) and advanced over the air Output and beamforming) and advanced over the air modulation and coding methods to achieve unprecedented modulation and coding methods to achieve unprecedented wireless data rateswireless data rates

• Many client devices and access points from leading vendors Many client devices and access points from leading vendors are “n” readyare “n” ready

• May operate in the 2.4 GHz band and 5 GHz bandMay operate in the 2.4 GHz band and 5 GHz band

• In mixed mode deployments, 802.11n performance will be In mixed mode deployments, 802.11n performance will be degraded somewhat by 802.11 a/b/g clients, but may improve degraded somewhat by 802.11 a/b/g clients, but may improve connectivity performance of 802.11 a/b/g clientsconnectivity performance of 802.11 a/b/g clients

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““SIGNALING” DATA RATE SIGNALING” DATA RATE vs. vs.

DATA THROUGHPUTDATA THROUGHPUT

““Signaling” data rate: Over the air modulation rate Signaling” data rate: Over the air modulation rate commonly used to specify the productcommonly used to specify the product

Data throughput: effective Ethernet throughput at the Data throughput: effective Ethernet throughput at the connectorconnector

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In PracticeIn Practice

TechnologyTechnology ““Signaling” Signaling” data ratedata rate

nominal data nominal data throughputthroughput

100Base-T 100Base-T wired Ethernetwired Ethernet

100 Mb/s 100 Mb/s >90 Mb/s>90 Mb/s

802.11 b 802.11 b wirelesswireless

11 Mb/s11 Mb/s ~ 5-6 Mb/s~ 5-6 Mb/s

802.11 g 802.11 g wirelesswireless

54 Mb/s54 Mb/s ~ 20-25 Mb/s~ 20-25 Mb/s

802.11 n 802.11 n wirelesswireless

300 Mb/s300 Mb/s ~ 90 - 150 Mb/s~ 90 - 150 Mb/s

OrOr

6 x 6 x performanceperformance

““SIGNALING” DATA RATE SIGNALING” DATA RATE vs. vs.

DATA THROUGHPUTDATA THROUGHPUT

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The difference is that the wireless connection has more The difference is that the wireless connection has more packet overhead and lower bit density in the signalingpacket overhead and lower bit density in the signaling

And remember-And remember-

Wireless access points are (somewhat)Wireless access points are (somewhat) like Ethernet hubs like Ethernet hubs - They share a collision domain, and they are half duplex.- They share a collision domain, and they are half duplex.

““SIGNALING” DATA RATE SIGNALING” DATA RATE vs. vs.

DATA THROUGHPUTDATA THROUGHPUT

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TYPICAL PRODUCT DATA RATETYPICAL PRODUCT DATA RATE

Vendors Claim >100Mb/s data throughput rates per radio, Vendors Claim >100Mb/s data throughput rates per radio, > 200 Mb/s for two radios. > 200 Mb/s for two radios.

SO….SO….

requires cabling for 1000Base-T (Gigabit Ethernet) versus requires cabling for 1000Base-T (Gigabit Ethernet) versus 100Base-TX (Fast Ethernet). 100Base-TX (Fast Ethernet).

CAT5e or better, & will be less tolerant of cabling errors CAT5e or better, & will be less tolerant of cabling errors

Is the AP,Is the AP, switch, and/or controller port 1000Base-T (gigabit) switch, and/or controller port 1000Base-T (gigabit) capable? capable?

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INFRASTRUCTURE BANDWIDTHINFRASTRUCTURE BANDWIDTH

What is the uplink bandwidth required when aggregating multiple What is the uplink bandwidth required when aggregating multiple APs? (using an over-subscription factor of 20, for example)APs? (using an over-subscription factor of 20, for example)

48 port switchController A

AP 2 AP 3 AP 48

200 Mb/s ea.peak

48 X (200 Mb/s) 20 (over-subscription factor)

Controller B480 Mb/s

960 Mb/s ea.

= 480 Mb/s

AP 1 AP 4

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TIA GUIDELINES FOR CABLINGTIA GUIDELINES FOR CABLING

Telecommunications Systems Bulletin TSB-162 Telecommunications Systems Bulletin TSB-162 Telecommunications Cabling Guidelines for Wireless Access Telecommunications Cabling Guidelines for Wireless Access Points (APs) provides guidelines on the topology, design, Points (APs) provides guidelines on the topology, design, installation, and testing of cabling infrastructure for installation, and testing of cabling infrastructure for supporting wireless local area networks (WLANs) in supporting wireless local area networks (WLANs) in compliance with the ANSI/TIA/EIA-568-B.2 and TIA-569-B compliance with the ANSI/TIA/EIA-568-B.2 and TIA-569-B standards for supporting wireless LAN in customer standards for supporting wireless LAN in customer premises.premises.

TSB-162 was created by the TIA TR-42 engineering TSB-162 was created by the TIA TR-42 engineering committee and released in March of 2006. TSB-162 is not a committee and released in March of 2006. TSB-162 is not a standard, but rather contains technical material that may standard, but rather contains technical material that may be useful to industry and users.be useful to industry and users.

*Cabling Installation & Maintenance March, 2006

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TIA GUIDELINES FOR CABLINGTIA GUIDELINES FOR CABLING

TSB-162 states that cabling should be installed and performance tested per existing 568-B.2 standards.

Determination of exact cell size and placement of the AP is outside the scope of the TSB (perform a site survey or simulation)

TSB-162 include wall-mount above the drop ceiling, wall-mount below the drop ceiling, and in-grid ceiling mount.

Telecommunications Enclosures (TEs) can be mounted in a ceiling panel to provide locked security or aesthetics for APs

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CELL SIZECELL SIZE

The TSB includes an example of a 60-foot by 60-footsquare cell structure

This agrees reasonably well with vendor recommendations for 3,000 sq. ft. “cell” sizes to support wireless voice over IP

X=18.3 m(60 ft)

r=13m(42 ft)

Hmax=80 m(262 ft)

Patch=6m(20 ft)

TO

AP

TR

EQUIPMENT(switch)

Lmax=13 m(42 ft)

3,600 sq.ft. square cell

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TIA 569-B TIA 569-B Telecommunications PathwaysTelecommunications Pathways

Telecommunications Enclosure (TE) may be used to enclose APs

The use of suspended ceiling space for horizontal connection points may be acceptable, provided that the space is accessible without moving building fixtures, equipment or heavy furniture

Access to the TE shall be controlled against unauthorized access

Cables that enter the TE shall be protected from sheath abrasion and conductor deformation by means of grommets, bushings andsuitable cable management hardware

A TE should serve an area not greater than 3,600 sq. ft.

A minimum of 3” clear vertical space shall be available above the ceiling tiles for horizontal cabling and pathway

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POWER OVER ETHERNETPOWER OVER ETHERNET

• Most vendor wireless access points can be powered by Most vendor wireless access points can be powered by IEEE 802.3af PoE. There are some exceptions, requiring IEEE 802.3af PoE. There are some exceptions, requiring 802.3at (802.3at (PoE Plus)PoE Plus)

• 802.11n products typically require close to 12.95 W if 802.11n products typically require close to 12.95 W if both radios usedboth radios used

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OTHER CONSIDERATIONS OTHER CONSIDERATIONS

- Although 802.11n is capable of providing coverage over - Although 802.11n is capable of providing coverage over large areas, recommend using the same density of access large areas, recommend using the same density of access points used in 802.11 a/b/g networkpoints used in 802.11 a/b/g network

- This is consistent with TIA standards, vendor This is consistent with TIA standards, vendor recommendations, and anticipates applications requiring a recommendations, and anticipates applications requiring a higher signal to noise ratio than datahigher signal to noise ratio than data

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COAX CABLING TO ANTENNASCOAX CABLING TO ANTENNAS

- 802.11n access points may require three to six antennas- 802.11n access points may require three to six antennas

- Some access points have non-detachable or integrated antennasSome access points have non-detachable or integrated antennas - Ideally, antennas are unobstructed by ceiling tiles and other Ideally, antennas are unobstructed by ceiling tiles and other objectsobjects

- Antennas should be spaced aboutAntennas should be spaced about4” apart (2.4 GHz), and 2” apart4” apart (2.4 GHz), and 2” apart(5GHz) or greater. Beyond that,(5GHz) or greater. Beyond that,there is there is not not a need to “spacea need to “spacein increments of a wavelength”in increments of a wavelength”

- Use suitably rated coax such as Use suitably rated coax such as UL Type CL2PUL Type CL2P

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INSTALLING IN THE “PLENUM” INSTALLING IN THE “PLENUM” vs. THE AIR HANDLING SPACEvs. THE AIR HANDLING SPACE

- Ideal location for access point is in the ceiling, but……Ideal location for access point is in the ceiling, but……

National Electric Code (NEC) regarding the plenum used for National Electric Code (NEC) regarding the plenum used for environmental air…….environmental air…….

- Article 300.22(b) “Article 300.22(b) “Equipment and devices shall be permitted within Equipment and devices shall be permitted within such ducts or plenum chambers only if necessary for their direct such ducts or plenum chambers only if necessary for their direct action upon, or sensing of, the contained airaction upon, or sensing of, the contained air” ”

-NEC Article 100 defines plenum as “NEC Article 100 defines plenum as “A compartment or chamber to A compartment or chamber to which one or more air ducts are connected and that forms part of which one or more air ducts are connected and that forms part of the air distribution systemthe air distribution system”. ”.

- NEC article 300.22(c) “NEC article 300.22(c) “The space over a hung ceiling used for The space over a hung ceiling used for environmental air-handling purposes is an example of the type of environmental air-handling purposes is an example of the type of other space to which this section appliesother space to which this section applies”, (Air-handling space as ”, (Air-handling space as opposed to a plenum space)opposed to a plenum space)

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- NEC article 300.22(C)(2) “NEC article 300.22(C)(2) “Electrical Electrical equipment with a metal enclosure, equipment with a metal enclosure, (or (or otherwise listed)otherwise listed) shall be permitted to shall be permitted to be installed in such be installed in such other spaceother space unless prohibited elsewhere in this unless prohibited elsewhere in this Code”Code”..

- NEC article 300.23 “NEC article 300.23 “cables, race-cables, race-ways and equipment installed behind ways and equipment installed behind panels, including suspended ceiling panels, including suspended ceiling tiles, shall be arranged and secured tiles, shall be arranged and secured so as to allow removal of panels and so as to allow removal of panels and access to the equipment.”access to the equipment.”

N.E.C. COMPLIANCEN.E.C. COMPLIANCE

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PREPARING FOR THE FUTURE PREPARING FOR THE FUTURE

- Cable for the future. Faster wireless standards in the works, but nothing - Cable for the future. Faster wireless standards in the works, but nothing eminent eminent

- Gigabit Ethernet to the AP probably adequate for some time into the Gigabit Ethernet to the AP probably adequate for some time into the future future

- In Healthcare, the Joint Commission has established rules for mitigating In Healthcare, the Joint Commission has established rules for mitigating the spread of infectious disease and contaminants- limiting access to the the spread of infectious disease and contaminants- limiting access to the air-handling space. TIA tech. committee TR-42 Health care facility cabling air-handling space. TIA tech. committee TR-42 Health care facility cabling task group.task group.

- Department of defense installations, & other government agencies may Department of defense installations, & other government agencies may require access point to be locked uprequire access point to be locked up

- Consider other RF services such as RFID, asset location, cellular, etc. Consider other RF services such as RFID, asset location, cellular, etc.

- RF cables- 802.11n has provisions for up to 8 antennas!RF cables- 802.11n has provisions for up to 8 antennas!

3/4/2009 .

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