Session ID-BRKEWN-3016
Understanding RF Fundamentals and the Radio Design of Wireless Networks
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 2
Session Abstract
This advanced session focuses on the deep-dive understanding of the often overlooked Radio Frequency part of the designing and deploying a Wireless LAN Network. It discusses 802.11 Radio, MIMO, Access Points and antenna placements, when to use a DAS system, antenna patterns… It covers the main environments such as carpeted offices, campuses and conference centers, and it provides feedback based on lessons learned from challenging deployments such as outdoor/stadium/rail deployments and manufacturing areas.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 3
Session Agenda - Objectives
What is radio how did we get here and what is frequency?
Basic 802.11 RF terminology and radio hardware identification
802.11 Antenna Basics – Single & Diversity Antennas
Interpreting antenna patterns – Cisco Richfield Facility
Diversity, Multipath, and the technical elements of 802.11n
DAS (Distributed Antenna Systems) overview – how used
Access Point Models and Features
802.11n design and deployment
Installations – above ceiling (plenum) – installations that went wrong
Antennas for Rugged Access Points – MIMO antennas for ceilings and walls
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 4
What We Won‘t Be Covering
Mesh deployments
Clean-Air (separate session for that)
Interference mitigation
Specific site survey utilities
LBS (Location Base Services)
FCC rules and regulations
WLAN management
802.11n beyond RF characteristics
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 5
What is radio? How did we get here and what is frequency?
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Basic understanding of Radio…
How fast the AC current goes is its ―frequency‖
AC is very low frequency 60 Hz (Cycles Per Second)
Radio waves are measured in kHz, MHz and GHz
The lower the frequency the physically longer the radio
wave – Higher frequencies have much shorter waves as
such, they take more power to move them greater
distances. This is why 2.4 GHz goes further then 5 GHz
(given same amount of RF power)
Popular Radio Frequencies:AM Radio 650 kHz = WSM 650 AM
Shortwave 3-30 MHz
FM Radio 88-108 MHz
Weather Radio 162.40 MHz
Cellular Phones 800-900 MHz
WiFi 802.11a 5 GHz
WiFi 802.11b/g 2.4 GHz
Battery is DC
Direct CurrentTypical home is AC
Alternating Current
AC Frequency 60 Hz
or 60 CPS – Cycles
Per Second Waves travel back and forth
so fast they leave the wire
Vintage RF
Transmitter
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 7
Each Frequency or sets of
frequencies (channels) have different
services such as Shortwave, FM
radio, television, etc - Most of these
are licensed services however some
like ―Wi-Fi‖ are ―unlicensed‖
Rest assured your Federal
Government knows these
frequencies well…DC Light
Radio Spectrum goes almost from DC to LightYou just need a radio receiver to “tune them in”
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 8
The US Radio Spectrum (3kHz-300GHz)
Uncle Sam has allocated the entire usable RF spectrum from DC to Light Source: US Department of Commerce http://www.ntia.doc.gov/osmhome/allochrt.PDF
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 9
Wi-Fi Portion of the Radio Spectrum
Wi-Fi is ―unlicensed‖ so it doesn‘t show up in
the overall spectrum allocation as a service
But it has beginnings in the ISM (industrial
Scientific Medical) band where it was not
desirable or profitable to license such short
range devices.
The first frequencies available
for Wi-Fi use was in the 900
MHz and 2.4 GHz range
As Wi-Fi popularity and usage
increased the FCC allocated
additional spectrum in the 5
GHz band for (unlicensed
usage)
Portions of the spectrum we
use today is licensed by
Amateur (Ham Radio) and
other services such as radio
location (weather radar)
There is more bandwidth in 5
GHz and mechanisms are in
place to co-exist with radio
location (radar) services
2.4 GHz 5 GHz
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 10
A radio needs a proper antenna
Cisco antennas are
identified by color
Blue indicates 5 GHz
Black indicates 2.4 GHz
As the frequency
goes up the radiating
element gets smaller
Antennas are custom made and have
frequency ranges and specifications
Omni-Directional antennas
like the one on the left,
radiate much like
a raw light bulb would
everywhere in all directions
Directional antennas like this
―Patch‖ antenna radiate
forward like placing tin foil
behind the light bulb or tilting
the lamp shade
Note: Same RF energy is
used but results in greater
range as its focused at the
cost of other coverage areas
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 11
Complex Modulation Schemes
Radio technology has a lot in
common with that old twisted pair
phone line that started out at 300
baud and then quickly increased
In order to get faster data rates,
(throughput) into the radio signal,
complex modulation schemes as
QPSK or 64 bit QAM is used.
Generally speaking, the faster the
data rate the more powerful the signal
needs to be (at the receiver) to be
successfully decoded.
Take-away here is that 802.11n is a
method of using special modulation
techniques and *not* specific to a
frequency like 2.4 or 5 GHz
802.11n can be used in either band
QAM or Quadrature Amplitude Modulation is one
of the fastest modulation types actually sending
two signals that are out of phase with each other
and then somehow ―putting all the pieces back
together‖ for even greater throughput.
This is one of the advantages of 802.11n
Example of 802.11n Modulation Coding Schemes
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 12
Wi-Fi Radio Spectrum
Even today many portable devices in use are limited to 2.4
GHz only including newer devices but this is changing
802.11b/g is 2.4 GHz
802.11a is 5 GHz
802.11n (can be either band) 2.4 or 5 GHz
The 2.4 GHz spectrum has only
(three non-overlapping channels
1,6 and 11 (US)
There are plenty of channels in
the 5 GHz spectrum and they do
not overlap
2.4 GHz and 5 GHz are different
portions of the radio band and
usually require separate
antennas
Most if not all 5 GHz devices
also have support for 2.4 GHz
Note: There are still many
2.4 GHz only devices today
primarily because those
chipsets are less costly to
produce
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 13
Basic 802.11 RF terminology and Radio Hardware Identification
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Common RF terms
Attenuation – a loss in force or intensity – As radio waves travel through objects or in media such as coaxial cable attenuationoccurs.
BER – Bit Error Rate - the fraction of bits transmitted that are received incorrectly.
Channel Bonding – act of combining more than one channel for additional bandwidth
dBd – abbreviation for the gain of an antenna system relative to a dipole
dBi – abbreviation for the gain of an antenna system relative to an isotropic antenna
dBm – decibels milliwatt -- abbreviation for the power ratio in decibels (dB) of the measured power referenced to one milliwatt of transmitted RF power.
Isotropic antenna – theoretical ―ideal‖ antenna used as a reference for expressing power in logarithmic form.
MRC – Maximal Ratio Combining a method that combines signals from multiple antennas taking into account factors such as signal to noise ratio to decode the signal with the best possible Bit Error Rate.
Multipath – refers to a reflected signal that combines with a true signal resulting in a weaker or some cases a stronger signal.
mW – milliwatt a unit of power equal to one thousandth of a watt (usually converted to dBm)
Noise Floor – The measure of the signal created from the sum of all the noise sources and unwanted signals appearing at the receiver. This can be adjacent signals, weak signals in the background that don‘t go away, electrical noise from electromechanical devices etc.
Receiver Sensitivity – The minimum received power needed to successfully decode a radio signal with an acceptable BER. This is usually expressed in a negative number depending on the data rate. For example the AP-1140 Access Point requires an RF strength of at least negative -91 dBm at 1 MB and an even higher strength higher RF power -79 dBm to decode 54 MB
Receiver Noise Figure – The internal noise present in the receiver with no antenna present (thermal noise).
SNR – Signal to Noise Ratio – The ratio of the transmitted power from the AP to the ambient (noise floor) energy present.
TxBF – Transmit beam forming the ability to transmit independent and separately encoded data signals, so-called streams, from each of the multiple transmit antennas
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 15
Identifying RF connectors
RP-TNC ConnectorUsed on most Cisco Access Points
―N‖ ConnectorUsed on the 1520 Mesh and 1400 Bridge
―SMA‖ Connector―Pig tail‖ type cable assemblies
―RP-SMA‖ ConnectorUsed on some Linksys Products
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 16
Identifying different cable types
LMR- 400 Foil & shield
LMR – 1200
½ inch solid copper cable sometimes
called ―hardline‖ or ―heliax‖ trade
names (side can be milled to be leaky)
Leaky Coax
shield cut away on one side
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 17
Antenna Cables – LMR Series
This is a chart depicting
different types of Times
Microwave LMR Series
coaxial cable.
Cisco uses Times
Microwave cable and has
standardized on two types:
Cisco Low Loss (LMR-400)
and Cisco Ultra Low Loss
(LMR-600).
LMR-600 is recommended
when longer cable distances
are required
Larger cables can be used
but connectors are difficult
to find and install
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 18
Antenna Cables
LMR-400 is 3/8 inch Cisco Low Loss
LMR-600 is ½ inch Cisco Ultra Low Loss
Trivia: LMR Stands for Land Mobile Radio
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 19
Antenna Cables - Plenum
If the cable is ORANGE in color it is usually
Plenum Rated.
Plenum is the air-handling
space that is found above
drop ceiling tiles or below
floors.
Because of fire
regulations this type of
cable must burn with low
smoke
The 3 Ft white cable
attached to most Cisco
antennas is plenum rated.
Our outdoor cable (black)
is not Plenum
Plenum cable is more
expensive
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 20
802.11 Antenna basics
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 21
Antenna basics
Antenna - a device which radiates and/or receives radio signals
Antennas are usually designed to operate at a specific frequency Wide-Band antennas can support additional frequencies but it‘s a trade-off and usually not with the same type of performance.
Antenna Gain is characterized using dBd or dBi
Antenna gain can be measured in decibels against a reference antenna called a dipole and the unit of measure is dBd (d for dipole)
Antenna gain can be measured in decibels against a computer modeled antenna called an ―isotropic‖ dipole <ideal antenna> and the unit of measure is dBi (i for isotropic dipole) (computer modeled ideal antenna)
WiFi antennas are typically rated in dBi.
dBi is a HIGHER value (marketing folks like higher numbers)
Conventional radio (Public safety) tend to use a dBd rating.
To convert dBd to dBi simply add 2.14 so a 3 dBd = 5.14 dBi
Again… dBd is decibel dipole, dBi is decibel isotropic.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 22
How does a Omni-directional dipole radiate?
The radio signal leaves the center wire using the ground wire (shield) as a counterpoise to radiate in a 360 degree pattern
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 23
Antenna theory (Dipole & Monopole)
Dipole
A dipole does not require a ground plane as the bottom half is the ground (counterpoise).
Monopole
A Monopole requires a ground plane – (conductive surface)
808 Ft Broadcast Monopole WSM 650 AM - Grand Ole Opry (erected in 1932)
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Antenna theory (dipole & monopole)
Monopoles were added to our antenna line primarily for aesthetics and require a metal surface to radiate
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How does a directional antenna radiate?Although you don‘t get additional RF power with a directional antenna it does
concentrate the available energy into a given direction resulting in greater range - much like bringing a flashlight into focus.
Also a receive benefit - by listening in a given direction, this can limit the reception of unwanted signals (interference) from other directions for better
performance
A dipole called the ―driven element‖ is placed in front of other elements.
This motivates the signal to go forward into a given direction for gain.
(inside view of the Cisco AIR-ANT1949 13.5 dBi Yagi)
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 26
Patch Antenna a look inside
9.5 dBi Patch, AIR-ANT5195-R
Patch antennas can have multiple radiating elements that
combine for gain. Sometimes a metal plate is used behind the
antenna as a reflector for more gain
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Antennas identified by color
Blue indicates 5 GHz
Black indicates 2.4 GHz
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Most common 2.4 GHz antennas for Access Points (single and diversity)
Antenna Description
AIR-ANT4941
2.2 dBi Swivel-mount Dipole; most popular
mounts directly to radio, low gain, indoor
AIR-ANT5959
2 dBi Diversity Ceiling-mount Omni
AIR-ANT1729
6 dBi Wall-mount Patch
AIR-ANT1728
5.2 dBi Ceiling-mount Omni
AIR-ANT3549
9 dBi Wall-mount Patch
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 29
Most common 5 GHz antennas for Access Points (single and diversity)
Antenna Description
AIR-ANT5135D-R3.5 dBi Omni-directional Antenna; mounts directly to radio, low gain, indoor
AIR-ANT5145V-R4.5 dBi Omni-directional Diversity Antenna; unobtrusive, ceiling mount, low gain, indoor
AIR-ANT5160V-R6 dBi Omni-directional Antenna; ceiling or mast mount, indoor/outdoor
AIR-ANT5170P-R7 dBi Patch Diversity Antenna;directional, small profile, wall mount, indoor/outdoor
AIR-ANT5195-R9.5 dBi Patch Antenna;directional, small profile, wall mount, indoor/outdoor
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 30
Understanding and interpreting antenna patterns
A quick peek at the Cisco Richfield Facility
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Understanding antenna patternsDipole (Omni-directional)
Low gain dipoles
radiate everywhere
think ―light bulb‖
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Understanding antenna patternsMonopole (Omni-Directional) MIMO
When three monopoles are next to each
other – the radiating elements interact
slightly with each other – The higher gain
4 dBi also changes elevation more
compared to the lower gain 2.2 dBi Dipole
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 33
Understanding antenna patternsPatch (Directional)
5 GHz Patch Antenna
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Understanding antenna patternsPatch (Higher Gain Directional)
Four element Patch Array
Single Patch Antenna
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Understanding antenna patternsSector (Higher Gain Directional)
AIR-ANT2414S-R
14 dBi Sector 2.4 GHz
Elevation plane has nulls due to high gain 14 dBi
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Understanding antenna patternsSector (Higher Gain Directional)
AIR-ANT2414S-R
14 dBi Sector 2.4 GHz
Elevation plane has nulls due to high gain 14 dBi
but antenna was designed with ―Null-Fill‖
meaning we scaled back the overall antenna
gain so as to have less nulls or low signal spots
on the ground.
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The Richfield Ohio (Aironet) facility A quick peek where antennas are designed...
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The Richfield Ohio (Aironet) facility designs antennas and qualifies 3rd party antennas
Satimo software compatible with
Stargate-64 System. Basic
measurement tool is 8753ES
Network Analyzer.
Cisco Anechoic chamber using an 18-inch
absorber all the way around 1-6 GHz
Anechoic means ―without echo‖
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FCC regulatory compliance testing is also done at the Richfield Ohio facility.
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Yes we have just a few Access Points…
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RF Screen rooms everywhereCopper shielding (Faraday Cage)
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Cables are typically fiber and exit
through well shielded holes
Doors have copper fingers and
latch tight forming an RF seal
RF Screen rooms Copper shielding on top metal on bottom
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RF Screen roomsCopper shielding (Faraday Cage)
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Cisco Richfield Facility
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Understanding multipath and diversity and the technical elements of 802.11n
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As radio signals
bounce off metal
objects they often
combine at the
receiver
This often results in
either an improvement
―constructive‖ or a
―destructive‖ type of
interference
Understanding MultipathMultipath can change signal strength
Note: Bluetooth type radios that ―hop‖ across the entire band can reduce multipath
interference by constantly changing the angles of multipath as the radio wave
increases and decreases in size (as the frequency constantly changes) however
throughput using these methods are very limited but multipath is less of a problem
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 47
Understanding MultipathMultipath reflections can cause distortion
As the radio waves bounce they can arrive
at slightly different times and angles causing
signal distortion and potential signal
strength fading
Different modulation schemes fair better –
802.11a/g/n uses a type of modulation
based on symbols and is an improvement
over the older modulation types used with
802.11b clients
802.11n with more receivers can
use destructive interference
(multipath) as a benefit.
Tip: It is still best to reduce
multipath conditions whenever
possible – Keep antennas away
from metal objects
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 48
Antenna placement considerations
Never mount antennas near
metal objects as it causes
increased multipath and
directionality
AP antennas need placements that are away from reflective surfaces for best performance
Avoid metal support beams, lighting and other obstructions.
When possible or practical to do so, always mount the Access Point (or remote antennas) as close to the actual users as you reasonably can
Avoid the temptation to hide the Access Point in crawl spaces or areas that compromise the ability to radiate well
Think of the Access Point as you would a light or sound source, would you really put a light there or a speaker there?
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 49
Non-802.11n diversity Access Points use two antennas sampling each antenna choosing the one with the least multi-path distortion
Cisco 802.11a/b/g Access Points start off favoring the right (primary
antenna port) then if multi-path or packet retries occur it will sample the
left port and switch to that antenna port if the signal is better.
Note: Diversity Antennas should always cover the same cell area
Understanding Diversity (SISO)802.11a/b/g diversity has just one radio
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 50
Receiver benefit as each antenna has a radio section
MRC is done at Baseband using DSP techniques
Multiple antennas and multiple RF sections are used in parallel
The multiple copies of the received signal are corrected and combined at Baseband for maximum SNR (Signal to Noise) benefit
This is a significant benefit over traditional 802.11a/b/g diversity where only one radio is used
Understanding Diversity (MIMO)MRC Maximal Ratio Combining (three radios)
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 51Presentation_ID © 2006 Cisco Systems, Inc. All rights reserved. Cisco Confidential 51
Understanding 802.11 MIMO terminology
MIMO (Multiple-Input-Multiple-Output)
Some RF components of 802.11n include:
MRC – Maximal Ratio Combining a method that combines signals from multiple antennas taking into account
factors such as signal to noise ratio to decode the signal with the best possible Bit Error Rate.
TxBF – Transmit beam forming – The ability to transmit independent and separately encoded data signals, so-
called ―streams‖ from each of the multiple transmit antennas.
Channel Bonding – Use of more than one frequency or channel for more bandwidth.
Spatial Multiplexing – A technique for boosting wireless bandwidth and range by taking advantage of multiplexing
which is the ability within the radio chipset to send out information over two or more transmitters known as ―spatial
streams‖.
Note: Cisco 802.11n Access Points utilize two
transmitters and three receivers per radio module.
MIMO is pronounced ―My Moe‖ not to be confused with this Moe.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 52
MIMO40Mhz
Channels
Packet
Aggregation
Backward
Compatibility
Technical Elements of 802.11n
MIMO 40Mhz ChannelsPacket
Aggregation
Backward
Compatibility
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Aspects of 802.11n
Beam Forming Spatial MultiplexingMaximal Ratio Combining
MIMO (Multiple Input, Multiple Output)
MIMO 40Mhz ChannelsPacket
Aggregation
Backward
Compatibility
Performed by
Transmitter
(Talk Better)
Ensures Signal
Received in
Phase
Increases
Receive
Sensitivity
Works with
non-MIMO and
MIMO Clients
Without Beam FormingTransmissions Arrive out of
Phase and signal is weaker
With Beam FormingTransmissions Arrive in Phase,
Increasing Signal Strength
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 54
Aspects of 802.11n
Beam Forming Spatial MultiplexingMaximal Ratio Combining
MIMO (Multiple Input, Multiple Output)
40Mhz ChannelsPacket
Aggregation
Backward
Compatibility
Performed by
Receiver
(Hear Better)
Combines
Multiple Received
Signals
Increases
Receive
Sensitivity
Works with
non-MIMO and
MIMO Clients
Performance
Multiple Signals Sent;
One Signal Chosen
Without MRC
Multiple Signals Sent and Combined
at the Receiver Increasing Fidelity
With MRC
MIMO AP
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 55
Aspects of 802.11n
Beam Forming Spatial MultiplexingMaximal Ratio Combining
MIMO (Multiple Input, Multiple Output)
40Mhz ChannelsPacket
Aggregation
Backward
Compatibility
Transmitter and
Receiver
Participate
Concurrent
Transmission on
Same Channel
Increases
Bandwidth
Requires MIMO
Client
Performance
stream 1
stream 2
Information Is Split and Transmitted on Multiple Streams
MIMO AP
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 56
20-MHz
20-MHz
40-MHzGained Space
MIMO (Multiple Input, Multiple Output)40Mhz Channels
Aspects of 802.11n
MIMO 40Mhz ChannelsPacket
Aggregation
Backward
Compatibility
Moving from 2 to 4 Lanes
40-MHz = 2 aggregated 20-MHz channels—takes advantage of the
reserved channel space through bonding to gain more than double the
data rate of two 20-MHz channels
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 57
40Mhz Channels
Aspects of 802.11n
Packet Aggregation
40Mhz ChannelsPacket
AggregationMIMO
Backward
Compatibility
Carpooling Is More Efficient Than Driving Alone
Without Packet Aggregation
Data
Unit
Packet
802.11n
Overhead
Data
Unit
Packet
802.11n
Overhead
Data
Unit
Packet
802.11n
Overhead
With Packet Aggregation
Data Unit
Packet
802.11n
OverheadPacketPacket
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 58
Packet AggregationBackward Compatibility
Aspects of 802.11nPacket
Aggregation
Backward
CompatibilityMIMO 40Mhz Channels
2.4GHz 5GHz
802.11ABG Clients Interoperate with 11n AND
Experience Performance Improvements
11n Operates
in Both
Frequencies
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 59
1 2 6 113 4 5 7 8 9 12 13 1410
2.402 GHz 2.483 GHz
40MHz 802.11n channel
Channel Bonding:
Wider channels means more bandwidth per AP
Understanding MCS rates and Channel Bonding
20 MHz channel
MCS rates 0-15 apply
Regardless of channel
Bonding.
MCS 0-7 is one Spatial Stream
When you bond a channel
You have a control channel and a
data (extension) Channel
Legacy ABG clients use control
channel for communication
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 60
2.4 GHz, 40 MHz Bandwidths
Tip: Channel bonding in 2.4 GHz should be avoided in enterprise deployments
Tip: Use 5 GHz as there are no overlapping channels to worry about
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 61
Example UNII-3 Channel Bonding
In 40-MHz you define the control channel this is the channel that
is used for communication by Legacy .11a clients.
The Extension channel is the bonded channel that High
Throughput ―HT‖ 802.11n clients use in addition to the control
channel for higher throughput as they send data on BOTH
channels
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 62
Channel Bonding - Subcarriers
When using the 40-MHz bonded channel, 802.11n takes advantage of the fact that each 20-MHz channel
has a small amount of the channel that is reserved at the top and bottom, to reduce interference in those
adjacent channels.
When using 40-MHz channels, the top of the lower channel and the bottom of the upper channel don't
have to be reserved to avoid interference. These small parts of the channel can now be used to carry
information. By using the two 20-MHz channels more efficiently in this way, 802.11n achieves slightly more
than doubling the data rate when moving from 20-MHz to 40-MHz channels
802.11n uses both 20-
MHz and 40-MHz
channels.
The 40-MHz channels
in 802.11n are two
adjacent 20-MHz
channels, bonded
together.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 63
Understanding Guard Interval
The guard interval
that is part of each
OFDM symbol is a
period of time that is
used to minimize
inter-symbol
interference.
This type of
interference is
caused in multipath
environments when
the beginning of a
new symbol arrives
at the receiver before
the end of the last
symbol is done.Default mode for 802.11n is 800 nanoseconds
If you set a shorter interval it will go back to long
in the event retries occur
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 64
54 48 36 24 Mbps
54 Mbps MRC
TxBF
Spatial Multiplexing
802.11a/g AP
(non-MIMO)
802.11n AP
(MIMO)
802.11a/g client
(non-MIMO)
802.11a/g client
(non-MIMO)
300 Mbps802.11n AP
(MIMO)
802.11n client
(MIMO)
MRC
TxBF
Spatial Multiplexing
MRC
TxBF
Spatial Multiplexing
802.11n OperationThroughput improves when all things come together
Channel Bonding
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 65
MCS index of 802.11n rates
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Understanding DAS Antenna SystemsOverview – How used
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Antenna Technologies ―DAS‖Traditional DAS deployments over coaxial cable
DAS – Distributed Antenna System
Mostly seen in healthcare, higher education & hospitality
Major benefits of DAS include:
Carry multiple wireless signals simultaneously (cellular, paging, etc)
Consolidates work above ceiling – fewer cables
Aggregates majority of active components in closet for easy replacement
Disadvantages
Usually one antenna per AP – lack of MIMO and diversity support
Cisco TAC will not support RF signal when radio is separated from the antenna on non-Cisco equipment
Compromises the benefits of CUWN‘s advanced features including RRM, Location, VoFi, etc.
Reduced technology migration paths - 802.11n can be more difficult to support
Large solid copper cable once installed, is difficult to move if changes are later required (remodeling etc).
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 68
How does DAS work?
DAS works by placing multiple radio services on a common cable or antenna system using selective filters and/or a low gain multiband antenna.
Two methods are typically used ―Leaky coax‖ and ―discrete wideband antennas‖ or sometimes a combination of both.
Tip: Avoid daisy-chaining antennas as this breaks key features like location/voice based services – use only discrete wideband antennas (one antenna per AP) with this type of DAS
Leaky ―radiating‖ coaxial cable
Bad for location based applicationsWide-Band antenna
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 69
Leaky coax DAS
Leaky coaxial systems are sometimes used in mining applications and assembly lines (think above assembly work benches)
For leaky coax to be effective, it needs to be installed in very close proximity to the actual WLAN users (distances are short typically 5-20 Ft) and will not work reliably at higher 5 GHz
frequencies. Limited to single channel - high potential for co-interference issues
Note: Leaky coax should be used for only the most basic Wi-Fi scenarios, i.e. light connectivity for low bandwidth apps. Not recommended for features such as voice or location
Cable has shielding removed
on one side – center radiates
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 70
Traditional coaxial DAS solutions
Depending on the type of ―wide band antenna‖ DAS system used, signals leave the Access Point‘s antenna port and go through RF filters
(passive) and/or bi-directional amplifiers (active) circuitry
While better then a leaky coaxial system, it is not a simple installation and requires professional installers with experience cutting and terminating the expensive (solid copper shielded) cable. Connector termination can
be a point of failure and cable moves can be expensive
Note: Unused antenna ports should be terminated to avoid interference to Access Points that are co-located
RP-TNC
Terminator
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 71
New approach In-building cellular – CAT 5e/6/6a
Cisco has a Solutions Plus Resell partnership with Mobile AccessWhereas Cisco resells the MA branded and supported product
Mobile Access active indoor cellular over same UTP
cable that can be shared with Cisco Access Points
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 72
New approachIn-building cellular – CAT 5e/6/6a
Mobile Access Pod using one UTP cable from the cellular controller can filter the cellular signals from the cable and pass GigE PoE
to the Cisco Access Point
• Eliminates the need for expensive solid copper cabling and the complexities of same
• Enables quicker and cost effective deployment with common UTP cabling
• Allows MA solution & Wi-Fi to co-exist on one single UTP cable
• No modifications or wide band antennas, no terminators are required on the AP
Note: Cisco Access Points with integrated antennas can also be used with this solution.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 73
Cellular and Wi-Fi sharing CAT-5e/6/6a
WLAN APSwitch
New / Existing Cat-5/6
Ethernet GigE
POE Alt A
WLAN
“802.11n”
Ethernet-LAN Traffic Passes
Over
0 to ~100 MHz
MobileAccessVE Shifts Carrier to
Intermediate Frequencies
Frequencies Starting at
140 MHz and Above
Shared Structured Cabling System is Passive to WLAN
and Cellular
Cellular
“Cell, PCS”
BDA, BTS,
Pico, Femto
Access
PodCellular
Controller
2 Cellular Bands
or 1 MIMO Service
POE Alt B
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 74
Co-existence of Wi-Fi and Cellular Antenna
Wi-Fi over Traditional DAS
Shared Coax cabling
APs in closet
No Cisco RF Support
Likely no MIMO, MRCor ClientLink, RRM,
Poor roaming, Location
Overlay
No Wi-Fi limitations
Expensive cabling
Duplicate cabling
Cellular over CAT5
No Wi-Fi limitations
Cheap UTP cables
RF signals limited by UTP cabling two for
CAT5 more with CAT6a
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 75
Access Point Models and Features
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 76
Ca
rpe
ted
R
ug
ge
diz
ed
11abg 11n + CleanAir11n
1130
12401260
3500e
3500i1140
Introduction of new Access Points
1250
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 77
AP 1130 AP 1140 AP 3500i AP 1240 AP 1250 1260 3500e
Integrated CleanAir No No Yes No No No Yes
Data Uplink (Mbps) 10/100 10/100/1000 10/100/1000 10/100 10/100/1000 10/100/1000 10/100/1000
Power Requirement 802.3af 802.3af 802.3af 802.3afE-PoE
802.3af*802.3af 802.3af
Installation Carpeted Carpeted Carpeted Rugged Rugged Rugged Rugged
Temp Range 0 to +40°C 0 to +40°C 0 to +40°C -20 to +55°C -20 to +55°C -20 to +55°C -20 to +55°C
Antennas Internal Internal Internal External External External External
Wi-Fi standards a/b/g a/b/g/n a/b/g/n a/b/g a/b/g/n a/b/g/n a/b/g/n
DRAM 32 MB 128 MB 128 MB 32 MB 64 MB 128 MB 128 MB
Flash 16 MB 32 MB 32 MB 16 MB 32 MB 32 MB 32 MB
Aironet Indoor Access Point Comparison
•802.3af fully powers single radio AP1250 or provides 1x3 performance on a dual radio 1250
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 78
Integrated antenna? – External antenna?
Integrated antenna versions
are designed for mounting
on a ceiling (carpeted areas)
where aesthetics is a
primary concern
Use for industrial applications
where external or directional
antennas are desired and or
applications requiring higher
temperature ranges
Carpeted areas Rugged areas
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 79
When to use integrated antennas
When there is no requirement for directional antennas and the unit will be ceiling mounted
Areas such as enterprise carpeted office environments where aesthetics are important
When the temperature range will not exceed 0 to +40C
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 80
When to use external antennas
Reasons to consider deploying a rugged AP
When directional ―focused‖ coverage is desired or greater range is needed
The environment requires a more industrial strength AP with a higher temperature rating of -20 to +55 C (carpeted is 0 to +40 C)
The device is going to be placed in a NEMA enclosure and the antennas need to be extended
You have a desire to extend coverage in two different areas with each radio servicing an independent area - for example 2.4 GHz in the parking lot and 5 GHz indoors
Requirement for outdoor or greater range Bridging application (aIOS version)
Requirement for WGB or mobility application where the device is in the vehicle but antennas need to be mounted external
Rugged AP in ceiling enclosure
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 81
When to use AP-1240 and AP-1250
Reasons to consider the AP-1240 or AP-1250
The AP-1240 and AP-1250 support higher gain antennas - a benefit only if a high gain antenna already exists or is required
Higher gain (up to 10 dBi) can improve WGB and outdoor Bridging distances
Recommend the AP-1240 if the infrastructure is older 10/100 ports and there is no interest in upgrading to 11n
AP-1240 will work with older Cisco PoE switches (Cisco proprietary power)
AP-1240 draws less power so better for solar applications
AP-1240 supports Cisco Fiber injectors
Tip: Higher than 10 dBi antenna gains are supported with the 1300 Series Bridge/AP
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 82
802.11n Design and Deployment
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 83
Phases of 802.11n deployment
Design Considerations
•Which AP to choose
•1:1 Replacement Strategy for Capacity
•5 GHz Strategy
•11n Clients
Planning
•WCS Planning Tool
•Infrastructure Considerations
Deployment
•Site Survey
Operation
•Configuration (40 MHz RRM, Data Rates, Security, etc.)
•Tracking and augmenting controller capacity
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 84
Which 802.11n Access Point is right?
AP-3500i and AP-3500e have the very latest Cisco features such as Clean Air Cisco‘s spectrum intelligence
AP-1140 and AP-1260 are of similar design less Cisco Clean Air features and can also run autonomous code (aIOS) for stand alone or Workgroup Bridge applications.
Note: 3500 Series does not support the older aIOS autonomous mode
All the Access Points were designed to have similar coverage for ease of deployment
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 85
AP1140 AP1250
AP3500i AP3500e
Coverage Comparison – 5GHz
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 86
1130 Access Point Placement
1130 Access Point Placement
1 per 5,000 sq feet for data only
1 per 3,000 sq feet for voice, location
Several
Supported Apps
Web
Radio Resource Management
Adaptive channel / power coverage
Operational simplicity
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 87
1140, 3500i Access Point Placement
Improved coverage at
higher data rates
1 for 1 replacement
AP1140, 3500i reuses existing
AP1130 T-Rail Clip
More Applications Supported
at Any Given Location
Web
Voice
Video
Backup
ERP
ABG
ABG
ABG
ABG
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 88
Access Points (Internal Antenna Models) Designed Primarily for ceiling (carpeted) Installations
Access Point has six integrated
802.11n MIMO antennas
4 dBi @ 2.4 GHz
3 dBi @ 5 GHz
Note: Metal chassis and
inverted ―F‖ antenna
elements were designed to
benefit ceiling installations as
the signal propagates
downward in a 360 degree
pattern for best performance
Antenna element
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 89
Antenna Patterns Azimuth and Elevation Patterns for 2.4 GHz & 5 GHz
2.4 GHz
Azimuth5 GHz
Azimuth
5 GHz
Elevation
2.4 GHz
Elevation
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 90
AP Placement – Wall Mounting
Wall mounting is acceptable
for small deployments such
as hotspots, kiosks, etc but
radiation is better on ceiling
Best for enterprise deployments as
coverage is more uniform
especially for advanced features
such as voice and location
AP-1140 and AP-3500i AP-1260 and AP-3500e
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 91
What about mounting options? Different mounting options for ceiling APs
Cisco has options to mount to
most ceiling rails and directly into
the tile for a more elegant look
Locking enclosures and different
color plastic ―skins‖ available from
third party sources such as
www.oberonwireless.com
www.terrawave.com
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 92
AP Placement—Evaluate Problem Areas
Object in Signal Path
Plasterboard wall
Glass wall with metal frame
Cinder block wall
Office window
Metal door
Metal door in brick wall
Phone and Head position
3 dB
6 dB
4 dB
3 dB
6 dB
12 dB
6 dB
Signal
Attenuation
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 93
Clips adapt Rail to ―T‖ bracket.Attaching to fine line ceiling rails
If the ceiling
rail is not wide
enough or too
recessed for
the ―T‖ rail this
can be
resolved using
the optional
clips
Part number for ceiling clips is AIR-ACC-CLIP-20=
This item is packaged in 20 pieces for 10 Access Points
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 94
Effective Frequency Use—5GHz and 2.4GHzCreate a 5GHz Strategy
5GHz Recommended for 802.11n
• More available spectrum—greater number of channels
• Reduced interference (no Bluetooth, Microwave Ovens, etc.)
• Maximum throughput in a 40MHz channel
• Many 11n devices only support 40MHz in 5GHz
2.4GHz still benefits from MIMO and packet aggregation
1
6 11
2
1 3 5 7 9 11
4 6 8 10
5GHz 40MHz Channels2.4GHz 20MHz Channels
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 95
11n Client Adapters
Make sure adapter is 11n Draft 2.0 or better certified by WiFi Alliance - http://www.wi-fi.org
802.11n adapters have a major influence on performance levels that can be achieved
Built-in 11n adapters out perform add-on
• USB and PCMCIA 11n adapters have less than optimal antenna placement as those form factors have less then ideal antenna spacing
Not realistic to upgrade most older laptops with internal 11n adapters
• Need three antennas connectors
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 96
11n Client Adapter Recommendations
Update 802.11n client drivers to the latest revision
Cisco-Intel relationship means that the Intel 11n adapter with Cisco‘s APs have had the most test time
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 97
WCS Planner1140 and 11n Support
Set AP type
Select ‗Enable 11n support‘
Select protocol ‗802.11a/n, b/g/n‘
Select optimize for HT
Select Voice & location if desired
Calculate/Apply/Add APs to Map
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 98
WCS PlannerData Rate Heat Map
Add APs to map
Set Heat Map type to Data Rates
Set Cutoff to desired minimum data rates
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 99
WCS PlannerProposal
Generate proposal
Use proposal for budgetary estimates
Use proposal with survey to create final install AP count and placement design
Recommend survey to validate and calibrate proposal results
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 100
Third Party Survey ToolsThere are many and I believe they are all good
Airmagnet
EDX
Ekahau
Helium Networks
Wireless Valley
… and many others
Tip: Survey and use Cisco antennas
If you contract this out, some companies use their
own antennas and then lock you into them saying
―that‘s what we surveyed with‖… if in doubt use
Cisco Advanced Services as they also perform
site surveys
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 101
Site SurveySite Survey Recommendations
Use ―Active Survey‖ tools
• Example - AirMagnet 6.0 uses Iperf to send traffic when surveying to measure actual data link speeds
Survey for lowest common client
• Once for 11a/g clients
• Once for 11n clients (optional)
Survey at intended AP power levels
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 102
11n Deployment ExpectationsData Services
Range
• 10-15% increase in maximum range versus a non-N AP
• Recommended 1:1 replacement of an 802.11a/g deployment
Coverage
• 10-20% increase in 802.11a/g high data rate coverage
• More uniform coverage and consistent coverage (MIMO)
Capacity
• Largest gain for 802.11n capable clients
• Maximum data rates of 144Mbps in 2.4GHz
• Maximum data rates of 300Mbps in 5GHz
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 103
1130 11G Survey
48 Mbps Coverage
86 Feet
1140 11G Survey
48 Mbps Coverage
102 Feet
Improved 802.11g Coverage1130 vs. 1140—11G Active Survey
18% Increase in 802.11g Coverage
Note the more uniform coverage of high (green) data rates
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 104
5GHz - Maximum Range
AP1130 – 5GHz AP1140 – 5GHz
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 105
802.11n DeploymentDesigning Around 5GHz 40MHz Channels
One AP
Data Rate vs. RSSIFull Deployment
Contiguous 5GHz Coverage
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 106
5 GHz Dynamic Frequency Selection
When Radar Is
Present
APs Shift
Channels—
Results in Lower
Available Channels
and Loss of UNI 2
and UNI 2e Bands Radar
Available
40MHz
Channels
No DFS
Support
DFS
Support
4 11
5 GHz Frequency
UNI 1 UNI 2 UNI 2 Ext. UNI 3UNI 2 UNI 2 Ext.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 107
DFS and Available Bandwidth
Full DFS support is required forcomplete use of channels in 5GHz
Limited DFS support directlyimpacts available bandwidth
Limited bandwidth restrictsapplication support andnegates investment in 11n
Available Channels per Region Theoretical Cisco Meru/Aruba
United States
11n 5GHz
20MHz24 21 8
11n 5GHz
40MHz11 9 4
Europe
11n 5GHz
20MHz19 19 4
11n 5GHz
40MHz9 9 2
Available Bandwidth in 5GHz for 11n
0
150
300
450
600
750
900
1050
1200
1350
Meru/Aruba Meru/Aruba Cisco Cisco
* 40 MHz Channels in 5GHz
600Mbps
300Mbps
1350Mbps 1350Mbps
US Europe
US
Europe
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 108
Tuning RRM 5GHz Channel SelectionUNII-2 Extended Channel Considerations
Wireless ->802.11a/n -> DCA
Uncheck channels 100-140
(UNII2-Extended)
Some older clients cannot utilize UNII-2 Extended Channels
The 5GHz radio could be ‗invisible‘ to the client
If your clients do not support these channels they can be disabled see below
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 109
Utilizing 11n Wide Channels20MHz vs. 40MHz Considerations
The 40MHz mode of 802.11n provides the highest throughput with data rates of 300Mbps
• Should not be utilized in the 2.4GHz band
• Not enough channels for 40 MHz mode
The 5GHz band has enough spectrum to make 40MHz feasible
• Use 20MHz for 802.11a voice deployments
• Use 40MHz for maximum data throughput with 802.11n clients
Use RRM for 40MHz
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 110
Mixed Mode Performance
11n
300 Mb54 Mb
WLAN Controller
11n
11g
Mixed mode experiences slight
performance impact due to ABG
clients
11n clients still transmit at full
performance
PHY and MAC for 11n provides co-
existence and protection for ABG
clients
Move 11n clients to 5GHz, keep
legacy clients at 2.4GHz
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 111
Improving Mixed Mode PerformanceDisabling Unnecessary Data Rates
Benefit: Beacons and Broadcast traffic utilize less ―airtime‖
For 802.11b/g deploymentsDisable: 1, 2, 5.5, 6 and 9Mbps
For 802.11g-only deploymentsDisable: 1, 2, 5.5, 6, 9 and 11Mbps
For 802.11a deploymentsDisable: 6 and 9 Mbps
Higher rates can also be disabled (ex. 12, 18Mbps) – dependant on deployment
Tuned 802.11b/g Data Rates:
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 112
Installations – Above Ceiling (Plenum) When they must be invisible
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 113
AP Placement in Plenum Areas
When placing the Access Point above the ceiling tiles (Plenum area) Cisco recommends using rugged Access Points with antennas mounted below the Plenum area whenever possible
Cisco antenna have cables that are plenum rated so the antenna can be placed below the Plenum with cable extending into the plenum
If there is a hard requirement to mount carpeted or rugged Access Points using dipoles above the ceiling – This can be done however uniform RF coverage becomes more challenging especially if there are metal obstructions in the ceiling
Tip: Try to use rugged Access Points and locate the antennas below the ceiling whenever possible
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 114
Installation above the ceiling tiles An optional rail above the tiles may be used
Note: The AP should be as close to the tile as practical
AP bracket supports this optional T-bar box hanger item 2
(not supplied) Such as the Erico Caddy 512 or B-Line BA12.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 115
Installation above the ceiling tiles Mount AP close to the tiles and away from objects
Installing Access Points
above the ceiling tiles
should be done only when
mounting below the ceiling
is not an option.
Such mounting methods
can be problematic for
advanced RF features
such as voice and location
as they depend on uniform
coverage
Try to find open ceiling areas away from
metal obstructions (use common sense)
Tip: Mount antennas either
below ceiling tile or the AP
as close to the inside of the
tile as possible
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 116
Plenum installs that went wrongYes it happens and when it does its bad…
When a dipole is mounted
against a metal object you
lose all Omni-directional
properties.
It is now essentially a
directional patch suffering
from acute multipath
distortion problems.
Add to that the metal pipes
and it is a wonder it works
at all.
Dipole antennas up against a metal box create a
patch like antenna - that plus metal pipes create
unwanted Multipath Destructive Interference
Tip: Try to get Access Points
close to the actual users – This
antenna is radiating forward
high in the ceiling where there
are no users - try to avoid these
types of installs
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 117
Plenum installs that went wrongHuh?? You mean it gets worse?
Antennas cannot radiate well with all this mess – someone went to a lot of
―trouble‖ to mount this -- just to encounter even more connectivity ―trouble‖.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 118
Installations that went wrong
Ceiling mount AP up against pipe not good
Antennas are obstructedMetal duct blocking antenna causing
Multipath interference
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 119
Installations that went wrong
Mount the box ―lid down‖ with
the antennas pointing
downward – Tip: Antennas do
not work well against metal
Patch antenna - Shooting across a metal
fence – Put it on a cross arm away from fence
or find a better location
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 120
Installations that went wrong
Sure glad this particular model runs a
bit on the warm side --- ―Chirp Chirp‖
I guess most dry wall guys
are not radio engineers –
Exactly how did this happen?
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 121
Minimize the Impact of Multipath
Temptation is to mount on beams or ceiling rails
This reflects transmitted as well as received packets
Dramatic reduction in SNR due to high-strength, multipath signals
Minimize Reflections When Choosing Locations
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 122
Antennas for Rugged Access Points802.11n options for ceilings and walls
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 123
Guide to Antenna part numbers
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 124
MIMO Ceiling Antenna 2.4 GHzAIR-ANT2430V-R (3 dBi ceiling mount Omni)
Antenna has three
monopole elements
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 125
MIMO Ceiling Antenna 5 GHzAIR-ANT5140V-R (4 dBi ceiling mount Omni)
Antenna has three
monopole elements
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 126
AIR-ANT2451NV-R2.4 GHz (2.5 dBi) & 5 GHz (3.5 dBi) dual band ceiling omni
Six leads - 5 GHz antennas have blue markings (shrink wrap)
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 127
AIR-ANT2460NP-R2.4 GHz 6 dBi Three Element Patch
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 128
AIR-ANT5160NP-R5 GHz 6 dBi Three Element Patch
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 129
AIR-ANT2450NV-R= & AIR-ANT5140NR-RMIMO “Multi-mount” Omni 2.4 GHz and 5 GHz
New 3 in 1 Antenna for 2.4 GHz and 5 GHz.
Gain should be 4 dBi for each antenna – but may be higher depending on how much gain we can achieve.
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 130
New Cisco Antenna part numbers
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 131
Outdoor weatherproofingCoax-Seal can be used with
or without electrical tape.
Taping first with a quality
electrical tape like Scotch 33+
vinyl allows the connection to
be taken apart easier.
Many people tape then use
Coax-Seal then tape again
this allows easy removal with
a razor blade.
Note: Always tape from the
bottom up so water runs over
the folds in the tape. Avoid
using RTV or other caustic
material.www.coaxseal.com
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 132
Links
Cisco Antenna Reference Guide http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/product_data_sheet09186a008008883b.html
Antenna Product portfolio http://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/at_a_glance_c45-513837.pdf
New 3500 datasheets http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps10981/data_sheet_c78-594630.html
Antenna Patterns and their meanings https://www.cisco.com/en/US/prod/collateral/wireless/ps7183/ps469/prod_white_paper0900aecd806a1a3e.html
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 133
Q and A
© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 134
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© 2010 Cisco and/or its affiliates. All rights reserved. Cisco PublicPresentation_ID 135