Cisco 802.11n Speeds

7/31/2019 Cisco 802.11n Speeds

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1 2009 Cisco Systems, Inc. All rights reserved. Cisco PublicBRKCAM-3007

Understandinghigh speed 802.11nwireless networks

in depth

BRKCAM-3007


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2009 Cisco Systems, Inc. All rights reserved. Cisco PublicBRKCAM-3007 3

Agenda

802.11n Technology Fundamentals

802.11n Access Points1140 and 1250

Design and Deployment

Planning and Design for 802.11n in Unified Environment

Key Steps for Configuration of 11n in a Unified Environment

11n Client Adapters

11n Troubleshooting


4/102 2009 Cisco Systems, Inc. All rights reserved. Cisco PublicBRKCAM-3007 4

802.11n Advantages

Increased Bandwidthfor emerging and

existing applications

Reduced Retriespermitting low latency

and delay sensitiveapplications such asvoice

Reduced dead spotspermitting consistent

connectivity for everyapplication

Throughput Reliability Predictability



40Mhz

Channels

Packet

Aggregation

Backward

Compatibility

Technical Elements of 802.11nMIMO 40Mhz Channels Packet

AggregationBackward

Compatibility



MIMO (Multiple Inputs Multiple Outputs)

MIMO is pronounced mee-moh or my-moh

802.11n it is mandatory requirement to have at leasttwo receivers and one transmit per band

Optional to support up to four TXs and four RXs

MRCMaximum ratio combining

SMSpatial multiplexing

Note: MIMO provides improvements for non-n802.11 clients *


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Comparing SISO and MIMOSignal Reception

One radio chain

Switches between antennas

Either A or B

Multipath degrades

Three radio chains

Aggregates all antennas

A and B and C

Multipath improves

Better immunity to noise

Better SNR than SISO

DS

PRadio Radio

Radio

Radio


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MIMO Radio Terminology

TxR:S

Transmit Antennas x Receive Antennas : Spatial Streams

T Transmit Antennas

R Receive Antennas

S Spatial Streams (1 = 150Mbps, 2 = 300Mbps)

The 1250 and 1140 are 2x3:2

Two Transmit, Three Receive, Two Spatial Streams


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Maximum Ratio Combining

Performed at receiver (either AP or client)

Combines multiple received signals Increases receive sensitivity

Works with both 11n and non-11n clients

MRC is like having multiple ears to receive the signal


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Illustration of Three MultipathReflections to SISO AP

MultipathReflections ofOriginal Signal

Signal EachAntenna Sees

Due toMultipath Effect

Radio Switchesto Best Signalwith Least

Multipath Effect

Radio


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Illustration of Three MultipathReflections to MIMO AP with MRC

The DSP Adjuststhe Received SignalPhase So They CanBe Added Together

The Resulting SignalIs Addition of

Adjusted ReceiveSignals

Multipath Reflectionsof Original Signal

DS

PRadio

Radio

Radio


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MIMO vs. SISO Dead Spot Assessment

Y-Axis MovementY-Axis MovementX-Axis MovementX-Axis Movement


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SISO vs. MIMO Dead Spots

1240 with Intel 3945ABG 1250 with Intel 5300AGN92 90 96 84 92 90 90 89 89 84 88 89 91 95

90 90 92 89 90 94 98 93 91 90 89 86 92 92

98 91 96 96 98 92 90 92 92 90 90 90 95 92

91 97 91 97 92 91 89 91 90 95 91 96 90 99

97 92 91 92 90 94 90 91 89 90 91 90 90 97

98 92 90 85 94 91 99 88 91 90 97 95 97 93

92 92 89 89 95 91 86 94 92 91 97 91 92 98

99 97 90 99 97 93 94 90 93 92 90 93 94 9996 96 97 95 95 94 89 90 90 97 96 90 97 98

96 98 99 91 97 92 95 91 96 98 97 95 93 98

98 93 91 99 96 89 96 91 91 92 93 97 93 100

91 96 91 89 92 93 91 91 96 94 92 93 99 97

96 97 96 98 96 98 96 96 98 96 99 97 98 98

98 98 98 98 92 98 96 95 90 91 96 98 98 99

82 77 39 83 80 83 88 78 71 65 64 80 25 64

38 52 54 48 71 85 85 52 70 69 89 66 91 68

67 89 71 81 48 80 69 56 72 45 45 86 91 89

70 75 70 49 85 55 56 88 62 78 69 75 73 93

58 67 80 62 70 90 69 65 91 69 55 69 70 61

57 69 67 71 90 70 21 71 69 68 53 68 92 67

70 89 74 66 67 69 58 68 88 65 68 87 90 91

28 90 31 90 57 69 90 75 64 71 89 89 88 8344 72 75 82 69 28 41 34 42 41 52 68 67 71

43 81 39 54 69 92 42 90 67 74 92 61 61 70

69 90 72 61 41 89 53 88 56 46 69 71 67 69

74 96 59 87 67 90 68 75 62 38 69 64 59 100

56 56 85 25 32 50 50 62 87 67 47 67 74 68

63 68 85 86 82 33 84 88 83 72 59 43 87 49

Each square represents a slight position change

Number is percentage of maximum throughput

802.11n provides more predictability through MRC


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Spatial Multiplexing

MIMO (Multiple Input, Multiple Output)

40Mhz Channels PacketAggregation

BackwardCompatibility

Transmitter andReceiverParticipate

ConcurrentTransmission onSame Channel

IncreasesBandwidth

Requires 11nClient

Performance

stream 1

stream 2

Information Is Split and Transmitted on Multiple Streams

MIMO AP


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SISO Data Transmission

RadioRadio

Thequickbrownfox

Data

TheTheThe

Data

Time Period 1

RadioRadioquickbrownfox

Data

quickquickThe

quick

Data

Time Period 2


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MIMO Spatial MultiplexingData Transmission

Thequickbrownfox

Data TheThe

Thequick

Data

Time Period 1

Time Period 2

TXRadio

TX

Radio

quickquick

RX

Radio

RXRadio

DSP

DSP

brownfox

Data brownbrown

Thequickbrown

fox

Data

TXRadio

TXRadio

foxfox

RXRadio

RXRadio

DSP

DSP


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More Efficient Spectrum Utilizationwith MIMO Spatial Multiplexing

The data is broken intotwo streams transmittedby two transmitters atthe same frequency

DSP

DSP

TXRadio

TXRadio

Data

Data

Data

Stream B

Stream A

Data

I Can Recognize the TwoStreams Transmitted at

the Same Frequency Sincethe Transmitters Have

Spatial Separation UsingMy Three RX Antennaswith My Multipath and

Math Skills

Radio

Radio

Radio


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MIMO Packet

Aggregation

Backward

Compatibility


AggregationBackward

Compatibility


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MIMO (Multiple Input, Multiple Output)40Mhz Channels

40-MHz ChannelsMIMO 40Mhz Channels Packet

AggregationBackward

Compatibility

Moving from 2 to 4 Lanes

40-MHz = 2 aggregated 20-MHz channelstakes advantage of thereserved channel space through bonding to gain more than double thedata rate of 2 20-MHz channels


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Double Wide Channel40-MHz Wide Channel Support

802.11n supports 20 or 40 MHz wide channels40 MHz wide channels recommended only for 5 GHz

Consists of a primary channel and a secondary channel

also referred to as extension channelSecond channel must be adjacent

Can be above or below primary

Protection provided for 20 MHz wide client use

20-MHz

20-MHz

40-MHzGained Space


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40 MHz-Wide Channel

Spectrum Expert Trace for 40 MHz-wide channelchannel 36 primary and channel 40 extension


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MIMO 40Mhz

Channels

Packet

Aggregation

Backward

Compatibility


AggregationBackward

Compatibility


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40Mhz Channels

Aspects of 802.11n

Packet Aggregation

40Mhz Channels PacketAggregation

MIMO BackwardCompatibility

Carpooling Is More Efficient Than Driving Alone

Without Packet Aggregation

DataUnit

Packet

802.11nOverhead

DataUnit

Packet

802.11nOverhead

DataUnit

Packet

802.11nOverhead

With Packet Aggregation

Data Unit

Packet

802.11nOverhead

PacketPacket


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Packet Aggregation

All 11n devices must support receiving of either packetaggregation method A-MPDU or A-MSDU

A-MPDU packet aggregation is what 1250 and 1140will use for packet aggregation with block acknowledge

Without packet aggregation

With packet aggregation


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MIMO 40Mhz

Channels

Packet

Aggregation

Backward

Compatibility


AggregationBackward

Compatibility


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Packet AggregationBackward Compatibility

Aspects of 802.11nPacket

AggregationBackward

CompatibilityMIMO 40Mhz Channels

2.4GHz 5GHz

802.11ABG Clients Interoperate with 11n ANDExperience Performance Improvements

11n Operates

in BothFrequencies


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802.11n HT PHY

To provide legacy co-existence all 11n transmissionstoday use a mixed mode PHY that encapsulates the HTPHY in the Legacy PHY when transmitting at HT rates

Legacy devices degrade 11n device performancebased on duty cycle they use in the spectrum

Legacy 802.11n (HT)


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Co-existence of ABG/N APs

Benefits of 11n accrue to ABG clients

MIMO benefits ABG clients on the AP receive side from MRC

Backward Compatibility & Co-Existence

11n11g

11g 11n

300 Mb

54 Mb

48 Mb

36 Mb

28 Mb

WLAN Controller

Backwards CompatibilityCo-Existence at Controller Level

11n11g

11g 11n

300 Mb54 Mb

WLAN Controller

Roam

802 D R


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802.11n Data RatesMCSModulation and Coding Scheme

802.11a/b/g used data rates

802.11n defines MCS rates

77 MCS rates are defined by standard

1140 and 1250 support 16 (MCS 0-15)

Eight are mandatory

Best MCS rate is chosen based on channel conditions

MCS specifies variables such asNumber of spatial stream, modulation, coding rate, number offorward error correction encoders, number data subcarriers andpilot carriers, number of code bits per symbol, guard interval


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MCS Chart

MCSIndex

Modul-ation

SpatialStreams

802.11n Data Rate

20 MHz 40 MHz

L-GI S-GI L-GI S-GI

0

BPSK 1 6.5 7.2 13.5 151 QPSK 1 13 14.4 27 30

2 QPSK 1 19.5 21.7 40.5 45

3 16-QAM 1 26 28.9 54 60

4 16-QAM 1 39 43.3 81 90

5 64-QAM 1 52 57.8 108 120

6 64-QAM 1 58.5 65 122 135

7 64-QAM 1 65 72.2 135 150

8 BPSK 2 13 14.4 27 30

9

QPSK 2 26 28.9 54 6010 QPSK 2 39 43.3 81 90

11 16-QAM 2 52 57.8 108 120

12 16-QAM 2 78 86.7 162 180

13 64-QAM 2 104 116 216 240

14 64-QAM 2 117 130 243 270

15 64-QAM 2 130 144 270 300

Maximum

with 1 spatialstream

Maximumwith 2 spatial

streams

A Few More 802 11n Features


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A Few More 802.11n FeaturesUsed to Increase Performance

Beam forming

Reduced inter-frame spacing

Reduced guard interval

From 800ns to 400ns betweensymbols

QAM 64


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Cisco Next-Generation Wireless Portfolio

Cisco Aironet 1140 Series

Carpeted Indoor Environments

Easy to Deploy-Sleek design with integratedantennas

802.11n performance with efficient 802.3af power

Blends seamlessly into the environment

Cisco Aironet 1250 Series

Rugged Indoor Environments

Versatile RF coverage with external antennas

Flexible power options for optimal RF coverage


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11a/g to 11n Access Point Migration

Indoor Environments

Integrated Antennas

Rugged Environments

Antenna Versatility


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1140 vs 1250 Positioning

1140 1250

Deployment Indoor Ruggedized

Antennas Integrated External (RP-TNC)

Wired Uplink Gigabit Gigabit

Power Options PoE, AC, Pwr Injector PoE*, ePoE, AC, Pwr Injector

* 1250 runs on PoE with reduced performance


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1250 AP


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The Aironet 1250 Series Access Point

Modular

2.4 GHz Module

5 GHz Module

RP-TNC Antenna Connectors

10/100/1000 Ethernet port

Console port

Security lock

Ruggedized metal exterior

Mounting bracket uses same hole pattern

Runs either LWAPP or Autonomous Cisco IOS


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Full Performance

Power Injector

Full Performance

Local AC Power

1250 Power Options

Less Than Full Performance with Two Modules

Standard 802.3af PoE

Full Performance

Cisco Enhanced PoE

Aironet1250

Full 802.11nRequires MoreThan Standard

802.3af Powerover Ethernet

New Antennas for AP1250


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New Antennas for AP1250Use 3 Antennas for each band

Omni-Directional

Single enclosure with threeantenna elements

2.4 GHz 3dBi (AIR-ANT2430V-R)

5 GHz 4 dBi (AIR-ANT5140V-R)

Dipoles

New dipole without hinge (gray)

2.4 GHz 2.2 dBi (AIR-ANT2422DG-R)

5 GHz 3.5 dBi (AIR-ANT5135DG-R)

Also supports existing dipoles with hinge(black and white)

Blue dot indicates 5 GHz

Three

Elemen

ts

Three PoE Modes Supported


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Three PoE Modes Supportedwith 1250 AP

Enhanced mode use ~18.5 Watts (config port for 20 Watt)

3560-E Cisco IOS Version 12.2(44)SE

3750-E Cisco IOS Version 12.2(44)SE4500EX4648E , X4648+E Cisco IOS Version 12.2(44)SG

1250 injector

Optimized mode 16.8 Watts

6500X6148, X6148A , X6548 Cisco IOS Version 12.2(33)SXH2

PoE daughter cards: WS-F6K-48-AF, WS-F6K-GE48-AF

802.3af mode 15.4 Watts

Any 802.3af switch

Cisco IOS versions are minimum to support greater than .AF PoE mode

Maximum Data Link Speed


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pfor Three PoE Modes

Enhanced and optimized power mode deliver the sameperformance in 5 GHz because it uses two spatial streams

Enhanced and optimized power mode deliver sameperformance in 2.4 GHz for dense deployments

The difference is Optimized Max TX drops from 20 dBm withEPoE to 14dBm with Optimized

2.4 GHzMbps

5 GHzMbps

SpatialStreams

Enhanced

(18.5 Watts)

144 300 2

Optimized(16.8 Watts)

144 300 2

802.3af

(15.4 Watts)

72 150 1

Reduced Output Power

Reduced Performance

Full Performance


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WLC Showing PoE Mode in Use

Enhanced Mode Optimized Mode AF Mode

Maximum Throughput


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1140 AP


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Access Point

has the following:

Mode buttonConsole Port

Ethernet PortLocal Power

Note: Full 802.11n functionality using IEEE 802.3af (15.4 Watt)power

1140 Ports are on the back


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Infrastructure Considerations

AP Power

Power Over Ethernet (802.3af)

1250 Power Injector (AIR-PWRINJ4)

Local AC Power

Switch port uplink

Gigabit Ethernet RecommendedFast Ethernet will work

However, the wired uplink can become a bottleneck


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Still Three Antennas per Band

11401250

2.4GHz 4dBi

5GHz 3dBi

1140 Access Point


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Designed for Horizontal Mounting

Similarly to the AP1130, the AP1140 is designed to bemounted horizontally on the ceiling

Vertical mounting works but is not ideal

1140 M i B k


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1140 Mounting Brackets

Uses same T-Railsystem as AP1130

both bracket and T-Rail

included with unit

1140 S it M ti


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Access Point can be securedusing a Kensington style

locking cable, or secured inthe bracket using a common

padlock

1140 Security Mounting


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Planning and Designfor 802.11n

**

Ph f 11 D l t


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Phases of an 11n Deployment

Design Considerations

1:1 Replacement Strategy for Capacity

5GHz Strategy

Planning

WCS Planning Tool

Infrastructure Considerations

Deployment

Site Survey

Operation

Configuration (40MHz RRM, Data Rates, Security, etc.)

Tracking and augmenting controller capacity

1130 Access Point Placement


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1 per 5,000 sq feet for data only

1 per 3,000 sq feet for voice, location

Several SupportedApps

Email

Web

Radio Resource Management

Adaptive channel / power coverage

Operational simplicity



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Improved coverage athigher data rates

1 for 1 replacement

AP1140 reuses existing

AP1130 T-Rail Clip

More Applications Supported

at Any Given Location

Email

WebVoice

Video

Backup

ERP

ABG

ABG

ABG

ABG

Effective Frequency Use5GHz and 2.4GHzCreate a 5GHz Strategy


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Create a 5GHz Strategy

5GHz Recommended for 802.11n

More available spectrumgreater 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 packetaggregation

1

6 11

2

1 3 5 7 9 11

4 6 8 10

5GHz 40MHz Channels2.4GHz 20MHz Channels

Capacity PrinciplesCh l C it U 5 GH d 2 4 GH


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Channel Capacity: Use 5 GHz and 2.4 GHz

2.4 GHz clients using N will consume less spectrum

5 GHz will provide the most capacity for 802.11n clients

More available spectrumgreater number of channels

Greater speeds dues to 40 MHz channel the fact that many devices will onlysupport 40 MHz channel in 5 GHz

DFS support allows up to 1140 MHz wide channels to be used

in 5 GHz bandIf radar is detect in the area some UNI2 and UNI2 channels may disabled

5 GHz Frequency

UNI 1 UNI 2 UNI 2 Ext. UNI 3UNI 2 UNI 2 Ext.

2 2 5 2# 40 MHzChannels FCC

1140 Deployment ExpectationsData Services


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Data Services

Range

10-15% increase in maximum range versus an AP1130

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 versus an AP1130

Capacity

Largest gain for 802.11n capable clients

Maximum data rates of 144Mbps in 2.4GHz

Maximum data rates of 300Mbps in 5GHz

Throughput: Example 802.11a TCPPerformance Ideal Environment


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Performance Ideal Environment

Approximately 45% of link rate

Throughput: Example 802.11n 5 GHz40 MHz TCP Performance Ideal Environment


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40 MHz TCP Performance Ideal Environment

Approximately 65% of link rate

1140 Deployment ExpectationsAdvanced Services


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Advanced Services

Voice

Plan for the same number of calls per AP as 11a/g (15-25 calls)

Voice over WiFi phones still top out at 54Mbps

No 11n WiFi phones on the market right now

Expect better voice reliability, especially in the upstream

direction (Phone to AP)

Location

Accurate triangulation requires a density of one AP per ~3000

sqft.

Although an 11n AP can hear better, it doesnt mean locationrequires less density

11n DeploymentSite Survey Recommendations


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Site Survey Recommendations

Use Active Survey tools

AirMagnet 6.0 uses Iperf to send

traffic when surveying to measureactual data link speeds

Survey for lowest common client

Once for 11a/g clientsOnce for 11n clients (optional)

Survey at intended AP power

levels


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2.4GHz - Maximum RangeAP1130 2.4GHz AP1140 2.4GHz

Improved 802.11g Coverage1130 vs 114011G Active Survey


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1130 11G Survey

48 Mbps Coverage

86 Feet

1140 11G Survey

48 Mbps Coverage

102 Feet

1130 vs. 1140 11G Active Survey

Note the more uniform coverage of high (green) data rates


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5GHz - Maximum RangeAP1130 5GHz AP1140 5GHz

Improved 802.11a Coverage1130 vs. 114011A Active Survey


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1130 11A Survey

48 Mbps Coverage

86 Feet

1140 11A Survey

48 Mbps Coverage

97 Feet

1130 vs. 1140 11A Active Survey

Note the more uniform coverage of high (green) data rates

802.11n Coverage2.4GHz 20MHz Channel Size


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G 0 C a e S e

Maximum of 144Mbps in a 2.4GHz 20MHz channel

At 100ft average data rate is 100Mbps

100Mbps @ 100ft100Mbps @ 100ft

802.11n Coverage5GHz 20MHz Channel Size


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Maximum of 144Mbps in a 5GHz 20MHz channel



802.11n Coverage5GHz 40MHz Channel Size


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Maximum of 300Mbps in a 5GHz 40MHz channel





802.11n DeploymentDesigning Around 5GHz 40MHz Channels


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g g

One APData Rate vs. RSSI

Full DeploymentContiguous 5GHz Coverage

Five Principles for MaximizingCapacity with 802.11n


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1. Design for 5 GHz 40 MHz wide channelsand increased cell density

2. Design for lowest common denominatorlegacy clients when surveying with 1250 or1140

Plan to migrate client devices to 11n

Disable lower legacy rates

3. Minimize noise and interference effects

Use RRM for interference avoidance

Use Spectrum Expert to find interference source

4. Design for ePoE (for 1250) power and GigEto APs

5. Specify a good 802.11n client adapter

Design MethodWCS Planner


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Set AP type 1250 or 1140

Select enable 11n support

Select protocol 802.11a/n,bgn

Select optimize for HT

Select Voice and location if desired

Calculate/Apply/Add APs to Map

Use WCS Heat Map to Predict Data RateCoverage and AP Placement


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Add APs to MAP

Set Heat Map type to Data Rates

Set Cutoff to desired minimum data rates

WCS PlannerProposal


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Generate proposal

Use proposal for budgetary estimates

Use proposal with Lite or Full survey to create final installAP count and placement design

Recommend survey to calibrate proposal results

Network Capacity and Scalability


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Burst

0

300mb

Burst

0

300mb

Burst

0

300mb

Burst

0

300mb

BurstNormal

WLAN Controller

11n

11n

Mobility Group

WLAN Controller 2

11n 11n

Plan for system levelcapacity, not per APcapacity

Plan for throughput (60%of data rate)

Peak 1140 throughput is200-250Mbps

Additional controllerincreases capacity andimproves availability

Typical Ethernet network

oversubscription is 20:1 With 1140 APs at full

capacity, Cisco WLANcontrollers reach 10:1

11n

11n

11n

System Capacity

Add Controller

Controller Over-subscription Rates


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Even at 200Mbps per AP, high capacity controllersoversubscribed well within acceptable limits of 8:1.

21XX and WLCM platforms fully support 802.11nfunctionality

Potential bottlenecks can be removed by running in H-REAP

Monitor WLC Traffic Utilization


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Use 11n scaling report to monitor WLC utilization

Compare utilization to interface capacity to determine if AP load

should be redistributed or additional WLC capacity is needed


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Configurationof 802.11n in aUnified Environment

Enable 802.11n Mode to SupportHT Rates (On by Default)


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Enable 802.11n mode for the band

802.11a/n>High Throughput (802.11n)

802.11b/n>High Throughput (802.11n)

Configure RRM for 40 MHz Wide5 GHz Channels


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Wireless>802.11a/n>DCA Channel Width 40 MHz

Enable or Disable 5 GHz Channelsthat RRM Is Allowed to Assign


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Wireless>802.11a/n>DCA

Uncheckchannels100-140

(UNII2-Extended)

Manually Configuring40 MHz Wide Channel


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Wireless>802.11a/n>Configure AP

Must set channel assignment to Custom

Extension Channel is always set to one up from primary

Basic 11n ConfigurationWLAN Security


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y

No EncryptionGuest WLANs

WPA2/AES EncryptionEnterprise WLANs

To utilize 11n data rates, use either AES or no encryption.

Basic 11n ConfigurationWLAN QoS


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WMM Allowed WMM Required

To utilize 11n data rates, use WMM Allowed or Required

Configure Which Packets That AreAllowed to Be Aggregated MPDU


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(Cisco Controller) >config 802.11a 11nSupport a-mpdu tx

priority 0 enable

(Cisco Controller) >config 802.11b 11nSupport a-mpdu tx

priority 0 enable

(Cisco Controller)> show 802.11a/b

802.11n Status:

A-MPDU Tx:

Priority 0............................... Enabled

Priority 1............................... Disabled







Enables Priority 0(Best Effort)Aggregation


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Improving Mixed Mode PerformanceDisabling Unnecessary Data Rates


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Benefit: Beacons and Broadcasttraffic utilize less airtime

For 802.11b/g deploymentsDisable: 1, 2, 5.5, 6 and 9Mbps

For 802.11g-only deployments

Disable: 1, 2, 5.5, 6, 9 and11Mbps

For 802.11a deployments

Disable: 6 and 9 Mbps Higher rates can also be

disabled (ex. 12, 18Mbps)

dependant on deployment

Tuned 802.11b/g Data Rates:

Tips for Achieving the Best Performance


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1. Use 5 GHz 40 MHz wide channels

2. Consider increasing cell densities

3. Disable lower legacy data rates

4. Use full power modes for the 1250 by using injector orEPoE

5. Specify a good performing 802.11n client adapter


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802.11nClient Adapters

11n Client Adapters


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Make sure adapter is 11n Draft 2.0 certified by WiFiAlliance - http://www.wi-fi.org

802.11n adapters have a major influence onperformance levels that can be achieved

Built-in 11n adapters out perform add-on

USB and PCMCIA 11n adapters have less than optimalantenna placement

Not realistic to upgrade most older laptops with internal

11n adaptersNeed three antennas connectors

11n Client Adapter Recommendations


90/102


Update 802.11n client drivers to the latest revision

Cisco-Intel relationship means that the Intel 11n

adapter with Ciscos APs have had the most test time


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Troubleshooting

Troubleshooting ToolsDetermining If Client Associated at 11n HT Rates with WLC


92/102


Monitor >Clients

Protocol indicates if client associated with 802.11n HT rates

Troubleshooting ToolsDetermining If Client Associated at 11n HT Rates with WCS


93/102


Protocol shows if client associated at 11n HT rates

Client Status Windows


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20 MHz 144Mbps

40 MHz 300Mbps

Warning: Depending on

the Adapter, You MayNot Be Able to Trustthe Speed It Reports

Client Status OSX


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Applications>Utilities>Network Utility

Client Shows 11n SSID But Does NotConnect at 11n Data Rates


96/102


Does the client have a 11n adapter?

Some legacy clients will show that the AP support11n even though the that client does not support 11n

Is 11n support enabled in adapter driver?

Have 11n Adapter and Still Connectingat A or G Rates


97/102


What type of encryption is allowed for WLAN?

Must be AES or None

If WEP or TKIP will not support 11n HT rates Is WMM allowed?

WMM must be Enable or Require

If WMM disabled will not support 11n HT rates


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Recommended Reading

BRKCAM-3007


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Source: Cisco Press

BRKCAM 3007

Meet The Expert

T k th t f ti t Ci N t k 2009


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Q and A


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Documents

Cisco 802.11n Speeds