wireless lan radio spectrum management best practices

© 2011 Cisco and/or its affiliates. All rights reserved. Cisco Public BRKEWN-3013 1

Wireless LAN Radio: Spectrum Management Best Practices BRKEWN-3013


  The Challenge   Wireless Trends

Evolution of the WLAN

  Deploying with Spectrum in Mind Site Survey – A Word About Tools Cisco Radio Resource Management—RRM ClientLink, BandSelect, CleanAir

What We’re Going to Cover –


The Challenge


  You are breathing the physical layer

  RF reflects off things

  RF is absorbed by things

  It’s a shared medium (as such, not all RF is always yours)

  Requirements change in response to changes in the environment—not always helpful

  Yet, if implemented and maintained properly, it’s a technology enabler providing

Increased productivity Creative freedom Enhanced user experience—by putting the power of the network where the user lives and works

The Dynamic Nature of Spectrum


Mobility Refers to the Client— Not the Infrastructure

 Radio assets are fixed devices

 Autonomous AP channel and power must be set in advance

 Clients move about  Resource demands shift

with client location, and density

Clients Associate to AP with Strongest Signal


Even When Well Planned, Things Change

  Mission critical requires HA

  Client technology refresh—additional device types

  PDA’s, Tablets

  New neighbors?


Normal Range

Reduced Range

Degraded Range

Reduced Coverage from 20% to 80% Reduced Call Quality Most Video Rated “Unwatchable”

A Series of Papers on Wi-Fi Interference Concluded…

..That Dramatic Loss in Quality of Mobility Services Will Result When Wi-Fi Encounters Interference

Video Voice Data

http://www.cisco.com/en/US/products/ps9393/prod_white_papers_list.html

Does Non–Wi-Fi Interference Matter?


Wireless Trends


Enterprise Wireless Evolution From Best Effort to Mission Critical

System Management

Scalable Performance Self Healing &

Optimizing

Hotspot


“When the students returned this year, if you asked me what percentage of students are using the Wi-Fi network – I would have told you 40%. I was shocked to see 85% of them using the Wi-Fi network.”

Scott Ksander – September 2009 – Cisco Education TAB Purdue University


Expectation for Mission Critical Wireless

IT Lacks RF Resources and

Expertise vs.

Continued Growth and Reliance

on Wi-Fi Devices

I Can’t Do My Job Without Wireless. It Has to Work. ”

“ “

”

Wireless Is Best-Effort. I Can’t Support a Level 1 SLA.


Deploying with Spectrum in Mind


  Role of site survey is as important as ever—but has evolved   Evaluate the existing application requirements, available spectrum

and Clients   Focus should be on fixed infrastructure

AP placement

Density is important

Protocols supported

Rates supported

Interference sources

  Mitigating issues   Planning tools

Deploying with Spectrum in Mind

Designing for Sustainable Spectrum Management


A Word About Tools

 What you use is less important than how you use it

  Internal vs. external adapters Internal adapters – even the same model will have different antenna arays and placement for different model laptops External adapters – can be moved with the application – and provide consistent results – regardless of the platform used

 Use the same Tool to compare results!

 Recheck results from a known environment with version updates

 Free Tools – Nothing is Free

How to Compare Apples to Apples


Throughput Reduction

Interference Type Near (25 Feet)

Far (75 Feet)

2.4 or 5 GHz Cordless

Phones 100% 100%

Video Camera 100% 57%

Wi-Fi (Busy Neighbor) 90% 75%

Microwave Oven 63% 53%

Bluetooth Headset 20% 17%

DECT Phone 18% 10%

End User Impact

  Reduced network capacity and coverage

  Poor quality voice and video

  Potential complete link failure

IT Manager Impact   Potential security breaches

  Support calls

  Increased cost of operation

The Impact of a Crowded Spectrum Performance at Risk in Unprotected Networks

Source: FarPoint Group


  802.11 is CSMA/CA – collision avoidance

  CCA is Clear Channel Assessment – and is the listen before talk component of Collision Avoidance

  With 802.11n radios CCA is typically linked to Preamble/Start of packet

  Radios are better these days (mostly)

  CCA - is -65 and SOP is -85 dBm for 802.11b/g/a

  If you can hear it above these levels – you are sharing the spectrum

What Is CCA and SOP?


CCA Blocked or High

802.11n Traffic

Video Signal

Video Camera Duty Cycle 90-100%


How Does Interference Impact Wi-Fi? Separating the FUD from the Facts

  Collisions - Non Wi-Fi devices do not participate in our CA mechanism – they have their own rules

  No respect for Wi-Fi – results in: Corrupted packets

Increased retransmissions

Increased Duty Cycle

Less available bandwidth

  SNR – Signal to Noise ratio

High SNR Low SNR


802.11 and Duty Cycle – Channel Utilization

  Retransmit a packet

  Duty Cycle of interference is logarithmically proportionate to channel time available

  Busy network – less interference tolerance

  Less busy – might not even notice low levels of interference

  Bandwidth is like Money – the more you get the more you spend


Deploying with RRM in Mind


  What are RRM’s objectives? To dynamically balance the RF infrastructure and mitigate changes

Monitor and maintain coverage for all clients

Manage Spectrum Efficiency so as to maintain the optimal throughput under changing conditions

  What RRM does not do Substitute for a site survey

Correct an incorrectly architected network

Manufacture spectrum

RRM—Radio Resource Management


  Continuously monitors dynamic changes in environment Collection of statistics and metrics used by DCA, TPC, and CHDM

Provides assessment of the overall “RF health” of the network

  Stats/metrics include: Noise (e.g., radar, Bluetooth devices, microwave ovens)

Interference (802.11—rogue APs)

Signal – (our AP’s)

Load

RRM Monitors the RF Group


How Does RRM Do This?

  DCA—Dynamic Channel Assignment Each AP radio gets a transmit channel assigned to it Changes in “air quality” are monitored, AP channel assignment changed when deemed appropriate (based on DCA cost function)

  TPC—Transmit Power Control Tx Power assignment based on radio to radio pathloss TPC is in charge of reducing Tx on some APs—but may also increase Tx by defaulting back to power level higher than the current Tx level

  CHDM—Coverage Hole Detection and Mitigation Detecting clients in coverage holes Deciding on Tx adjustment (typically Tx increase) on certain APs based on (in)adequacy of estimated downlink client coverage


Case Study 1 – College High Rise Dorm Channel Utilization

• 26 story dormitory • Low user count – but high channel utilization • Did an Active site survey • Customer complaint – disconnects and low throughput


WCS – Channel Utilization Report

0 TX and 0 RX Utilization – Channel 40-70%?


  Duty Cycle is the on time of a given transmitter

  It is measured as percentage of total time available, this relates directly to channel utilization, but is only part of the story – protocol overhead is the full story

  802.11 can only do essentially two things to recover in a challenging RF environment

Retransmit a Frame – Turn the radio on again to send information that has already been sent once = Increased Duty Cycle

Rate shift to a slower speed that can be supported – If retries are excessive, then the link will be rate shifted to a slower speed in an attempt to gain reliability

  Both of these will increase Duty Cycle and make the problem worse if it is a dense network

Duty Cycle – and Spectrum Capacity


CCK DSSS OFDM

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

1 2 5.5 11 6 12 24 36 48 54 130 300

64 Byte

128 Byte

256 Byte

512 Byte

1024 Byte

2048 Bytes

Time/µS

Mbps

Frame Size/Bytes

Understand Protocol Selection 802.11 b/g/a/n and Duty Cycle—Important? Why?

Spectrum Is a Shared Finite Resource


Duty Cycle and Spectrum 802.11 b/g

Channel Separation

20-30% Duty Cycle

Healthy Network


Duty Cycle and Spectrum 802.11 b/g

No Channel Separation

100% Duty Cycle

Unhealthy Network


Channel Utilization— What Made the Difference?

What Made This Dramatic Change?

Before

5% After


Every SSID Counts!

  Each SSID requires a separate Beacon

  Each SSID will advertise at the minimum mandatory data rate

  Disabled – not available to a client

  Supported – available to an associated client

  Mandatory – Client must support in order to associate


Cell Size – By Protocol/Speed

Assuming 10% PER

Speed Required

SNR AP Sensitivity 1 0 -91 2 3 -91

5.5 6 -91 6 2 -87

11 9 -88 12 6 -86 24 11 -85 36 13 -85 48 17 -78

54 19 -77

Channel Utilization – Is the Aggregate of Every Radio on the Channel That Can Be Heard Above -85 dBm – This Means Clients Too


  Neighbor AP messages are sent every 60 seconds at highest power and lowest supported data rate

  Neighbor Messages are used by receiving APs and their WLCs to determine how to create inter and Intra-WLC RF Groups and Physical RF Neighborhoods

  Each AP listens for other AP’s neighbor messages – and if it’s RF Group name matches – the message is forwarded to it’s controller and ultimately to the RF Group leader

  A list is maintained for each AP in the RF Group of who heard his neighbor messages and how loud

RF Grouping Neighbor Messages = OTA – Over The Air - RF Analysis

Neighbor Messages Are Sent from Each AP to Multicast Address 01:0B:85:00:00:00


Noise, Interference, and Utilization via WLC

RX Utilization 36

TX Utilization 7

Channel Utilization 96


WLC Config Analyzer View


RF Summary – Imbalance Between Neighbors


WCS – Map View – Show Neighbors   Select any AP on the map and

right click   Select View RF Neighbors   Table displays (1) Neighbors

on the current map   Table displays (2) neighbors

not on the current map


Three APs Deployed in Each Foyer


Initial Measures – Before and After   Eliminated center 2.4 GHz radios – on each floor

  Eliminated all but 11 Mbps

  Enabled Client Link

  Enabled Band Steering


End Result – APs Moved


Case 2 – RF Groups

  After conducting a multi floor active site survey using a 4400 and 10 x 1140 AP’s, coverage looked good at power levels 2-3.

  The customer then deployed 3500 series AP’s according to the plan, and RRM set the power levels to 6!

  What’s different about the 3500?


RF Grouping


The Tell… Survey Was Conducted in Separate RF Group


> - 80dBm

Wireless Controller A RF Group = <asciii string>

Wireless Controller B RF Group = <ascii string>

RF Group Controllers Elect an RF Group Leader That Analyses RF Data and Neighbor Relationships to Make More Intelligent Decisions About Optimizing the RF Environment for the System

Neighbor Messages Are Sent At Full Power, Containing Information About the APs Seen, and Authenticated via a MIC Based on the RF Group Name

IF APs on Different Controllers Hear Neighbor Messages from APs in the Same RF Group at –80 dBm or Greater They Will Group in an RF Neighborhood, Channel, and Power Then Compute as a Group

About RF Groups RF Groups Are Clusters of Controllers that Share the Same RF Group Name. RF Neighborhoods Are Groups of APs that “Hear” Each Other


RF Neighborhood (a)

RF Neighborhood (b) RFGroup - Bob

RF Grouping and RF Neighborhoods   Multiple “RF Neighborhoods” can exist within a

single RF Group   RRM is calculated on a per RF neighborhood

basis   RF Neighborhoods can be inter-controller or

intra-controller   Multiple RF Neighborhoods may be formed

even when controllers share same RF Group name

RF Groups/Neighborhoods Apply per PHY Type

RFGroup - Bob

RF Neighborhood (B) RF Neighborhood (A)

RF Neighborhood (C)

RF Neighborhood (D)

RF Neighborhood (E)

Logical RF sub-group (c)

RFGroup 1 RFGroup 1

RF Neighborhood (A)

RF Neighborhood (B)

RF Neighborhood (C)


Configuring RF Grouping

By Default the RF Network Name and Mobility Domain Name Are the Same, but This Is Default Behavior

RF Group Name Is Configured From:   Controller > General on the WLC GUI:   Configure > Controllers > controller > System > General in WCS:


RF Grouping

 By looking at the RF neighborhoods from the network perspective, you can determine which APs are literally within the same RF domain or neighborhood.

 Placing like groups of APs into a separate RF group is perfectly ok, and in fact can provide much better design options


Case -3 DCA

  New Building installation

  CU has a very high density of I-phone’s

  Main Architect – good RF knowledge

  Without RRM – channel distribution matched plan

  With RRM – AP’s on same channel adjacent to one another

  Did not trust RRM Channel Utilization – vs. Spectrum Expert – did not match

Neighbor Lists and spot check with Client card – vastly different


Neighbor Message and AP Neighbors

Neighbor Messages Are Sent Every 60 Seconds to the Multicast Address of 01:0B:85:00:00:00

Did Not Trust RRM – Compared the Neighbor Lists for WLC to Beacon Observations at the AP

Produced Less Trust -


  Looking at the 1st floor we see two APs on the same channel

  At the 2nd floor, we see 3 APs

  The 3rd, we see 3 APs

  And the 4th we see 2 APs

  But look at the APs channels as they stack!

RRM Put Adjacent APs on the Same Channel!

1st 2nd

3rd

1

6

11

4th

1


WLCCA View


AP Placement

  Omni Antenna’s have an Elevation pattern of a donut

  12 dB attenuation between floors

  Customer intentionally stacked the AP’s to protect against direct exposure

  Had these been 1130’s – possibly a valid argument

BUT - These Are Cisco AP 1140s


Antenna Pattern Elevation Plane 2.4 GHz

Access Point Has 3 Integrated 4 dBi (2.4GHz) Antennas


DCA 6.0 and Beyond   CM= RSSI, Noise, Interference, signal, and a constant (threshold)

  An AP list ordered by CM’s in the RF Neighborhood is created worst to best

  Prior to release 6.0 – we solved for the worst AP CM in the RF Neighborhood

  6.0 and after - DCA now operates on multiple local searches – and randomly selects CPCI (channel Plan Change Initiators) from the CPCI list and calculates optimal solutions for the CPCI and it’s first and second hop neighbors

  The calculation completes with the NCCF function – a goodness value for the group – indicating positive change for the CPCI and it’s immediate neighborhood

Version Band High Medium Low 4.1.185.1 2.4 GHz 5 dB 15 dB 30 dB

5 GHz 5 dB 20 dB 30 dB 6.0 2.4 GHz 5 dB 10 dB 20 dB

5 GHz 5 dB 15 dB 20 dB


DCA Solution Flow

AP-5

CPCI

First Hop Neighbor

Second Hop Neighbor

Worst

Best

AP CM AP-5 25 AP-4 34 AP-6 55 AP-1 60 AP-7 63 AP-8 67 AP-23 68 AP-14 71 AP-13 73 AP-19 75 AP-24 76 AP-25 77 AP-16 78 AP-10 79 AP-15 79 AP-17 81 AP-2 82 AP-11 82 AP-20 83 AP-21 83 AP-22 84 AP-9 85 AP-18 87 AP-3 90 AP-12 91

AP-5 AP-6

AP-15 AP-11

AP-9

AP-10 AP-18

AP-19

AP-16

AP-21

AP-22

CPCI and First Hop Neighbor, Channel Change Is Allowed

The Impact on the Second Hop Neighbor Is Considered in the Calculation, but No Channel Change Is Permitted

A CPCI List Is Created of All APs in the Local RF Neighborhood


DCA Solution Flow

AP-5

CPCI

First Hop Neighbor

Second Hop Neighbor

Worst

Best


AP-5 AP-6

AP-15 AP-11

AP-9

AP-10 AP-21

AP-19

AP-16

AP-22

AP-18

NCCF Is Calculated on the Entire Group for Each Channel Plan Calculated – A Plan Is Selected


DCA Solution Flow

AP-5

CPCI

First Hop Neighbor

Second Hop Neighbor

Worst

Best


AP-5 AP-6

AP-15 AP-11

AP-9

AP-10

X X

X

X X

X

The CPCI – and Its First Hop Neighbors Are Removed from the CPCI List


DCA Solution Flow

AP-5

CPCI

First Hop Neighbor

Second Hop Neighbor

Worst

Best

AP-2 AP-19

AP-8 AP-7

AP-18

AP-22

AP CM AP-4 34 AP-1 60 AP-7 63 AP-8 67 AP-23 68 AP-14 71 AP-13 73 AP-19 75 AP-24 76 AP-25 77 AP-16 78 AP-17 81 AP-2 82 AP-20 83 AP-21 83 AP-22 84 AP-9 85 AP-18 87 AP-3 90 AP-12 91

The Process Begins Again with the Remaining APs on the List Randomization Is Applied for Selection of the Next CPCI


Redesigned DCA Benefits

  Faster Convergence– calculations for an RF group are much faster – can complete 6 iterations in the previous time it took for one.

  More Granular – more flexible for the dynamic needs of an RF Neighborhood

  System wide View – every AP’s assignment is known and managed by a centralized resource

  Much better for integrating Spectrum Intelligence and makes CleanAir integration exciting.


Back to Our Use Case -

  Don’t like RRM’s answer – what can be done?

  Change the question!

Move an AP on Either Floor Override Global for Just 1 AP and Let DCA Recalculate!


Case 4 – Transmit Power Control

  New construction

  Predictive site survey done for Vocera 11.b badges

  Predictive survey called for 25 – 30 foot spacing

  Power at 13 dBm power (power level 3) to cover

  TPC forced AP’s to power level 7

  Result was coverage holes for Voice


Voice Readiness Tool Results


New Building Borders with Existing Building and AP1130 Installation


Add APs – Fill Coverage Holes without Increasing Co-Channel Interference


  Assume an AP’s TX neighbors hear it at the following RSSI levels (listed in decreasing order; units are [dBm])

–45, –55, –67, –75, –78, –80

  For third loudest neighbor RSSI_3rd > TPC_Threshold TPC_Threshold = –70 dBm

  TPC would recommend a Tx power decrease

  Important: The RSSI_3rd >? TPC_Threshold criterion only determines if Tx decrease is recommended

Whether the actual decrease takes place depends on hysteresis

The “delta” between the current and the recommended Tx

Hysterisis for a TX Power increase is 3 dB

Hysterisis for a TX Power decrease is 3 dB

TPC—How It Works


  There are two main TX power scenarios that can trigger an increase There is no third neighbor – will result in maximum power

TPC Equation evaluates the recommended Tx_Ideal to be in between Tx_max and Tx_current (rather than lower than TX_current)

  Power decreases take place gradually –1 power level at a time (3 dB)

  TPC power increases happen immediately

TPC—How It Works


  Several changes to how power is calculated where made in the 6.0 MR-1 release

  A smoothing algorithm was added that takes into account the power levels of the next neighboring AP’s and their neighbors

  In situations where there is no third neighbor – the old algorithmic behavior was to default to power level 1 (no RSSI_3rd)

  With these changes, if there is no third neighbor TPC looks for any neighbors heard above the TPC threshold, and interrogates those neighbors that are heard above the current TPC Threshold

  An average of averages is factored against TPC recommended power

  That average is used to modify the recommendation from TPC

TPC 6.0 MR1 Algorithm Changes


AP-2 RX-TX Neighbor List

TPC - Example

AP-1

AP-2 AP-3

AP-4

AP-6

AP-5

Neighbor RSSI

ap2 - tx -45 dBm

ap6 - rx -55 dBm


Neighbor RSSI Power

Ap3 -45 dBm 5

Ap6 -55 dBm 4

Ap4 -57 dBm 5

ap5 -79 dBm 3

Neighbor RSSI Power

Ap2 -55 dBm 4

Ap3 -58 dBm 5

Ap4 -68 dBm 3

ap5 -71 dBm 4


• Ap1 has 2 neighbors, ap2 and ap6 • Ap2 has three neighbors above TPC Threshold of -70 • Ap6 has three neighbors above TPC Threshold of -70 • Average the power settings for all 6 neighbors • 4+5+3+5+4+5=26 26/6=4 • Use power level 4 in smoothing algorithm for final TPC recommendation of 3 for AP1


  From the controller GUI select-

Wireless=>802.11a/b=>RRM-TPC

TPC 6.0 MR1 Min/Max Power GUI Configuration

Note: Ensure You Select Apply in the Upper Right Hand Corner of the Screen to Save.


Facts

  At static power level 3 – no clients on the network – average channel utilization was 30-40%!

  At power level 7- Utilization was much lower at 10% – more representative of what the unloaded network should look like

  Three options under current RRM – Add more AP’s – too late

Split RF group into new group

Risky – live hospital borders 1 full side of the new building – separation was 6 meters

Use TPC Min Max settings to raise power levels in this building

Better – less risk of affecting neighboring AP’s


Use TPC Min/Max

  Set TPC Min/Max to 9 dBm and 6 dBm

  Network settled at power level 5

  Eliminated 1, 2 Mbps

  AP’s stayed at power level 5

  Channel Utilization Dropped

  Voice Survey showed good coverage


TPC Min/Max Power GUI Configuration   From the controller GUI select-

Wireless=>802.11a/b=>RRM-TPC

Note: Ensure You Select Apply in the Upper Right Hand Corner of the Screen to Save.


5 2.4

Optimized RF Utilization by Moving 5 GHz Capable Client Out of the Congested 2.4 GHz Channels

802.11n

BandSelect Access Point Assisted 5 GHz Band Selection

Dual-Band Client Radio 2.4/5GHz

Discovery Probes Looking for AP

Discovery Response

Solution BandSelect Directs Clients to 5 GHz Optimizing RF usage

  Better usage of the higher capacity 5GHz band

  Frees up 2.4 GHz for single band clients

Challenge Dual-Band Clients Persistently Connect to 2.4 GHz

  2.4GHz may have 802.11b/g clients causing contention

  2.4GHz is prone to interference


BandSelect Configuration – Per-SSID Override (Cont.)


802.11a/g Client Connection Not Optimized, Creates Coverage Hole

The Problem Beam Strength Not Directed to Client

802.11n

802.11a/g Beam Strength X


Intelligent Beam Forming Directs Signal to Improve Performance and Coverage for 802.11a/g Devices

Beam Forming 802.11a/g

802.11n

Up to 65% Improvement

The Solution Cisco Innovation: ClientLink


Higher Throughput per 11a/g Device

No Connection without

ClientLink

Throughput vs. Distance

Test: 802.11a/g Device with 802.11n Network Source: Miercom

Up to 65% Increase in Throughput

13.6%

87.7% 70.4%

89.5%


Test: 802.11a/g Device Measured at 16 Antenna Orientations with 802.11n Network Source: Miercom

  Faster data transmission, less retries = more efficient use of RF channel.

  Faster 11a/g transactions opens airtime for 11n devices, providing them improved experience

Higher System Capacity Up to 27% Improvement in Channel Capacity

Channel Util of 74.2% Channel Util of 45.2%


Detect and Classify

What Is CleanAir Technology?

Cisco CleanAir

High-Resolution Interference Detection and Classification Logic Embedded into Cisco’s 802.11n Radio ASIC. Inline Operation with no CPU or Performance Impact.

100

63

35

97

90

20

  CleanAir Radio ASIC   Uniquely Identify and

Track Multiple Interferers   Assess Unique Impact to

Wi-Fi Performance   Monitor AirQuality


  A Wi-Fi chip is a communications processor – a MODEM

  It only knows Energy that can be demodulated = Wi-Fi

Energy that can not be demodulated = Noise

  Noise is complicated – Collisions, fragments, corruption

Wi-Fi that is below sensitivity threshold of the receiver

  Peaks in Wi-Fi activity can cause all of the above to occure

Wi-Fi and Spectrum Knowledge – Why Is Silicon Important?


High Resolution Spectral Advantage

Typical Wi-Fi Chipset Spectral Resolution at 5 MHz

Cisco CleanAir Wi-Fi Chipset Spectral Resolution at 78 to 156 KHz

‘Chip View Visualization’ of Microwave Oven and BlueTooth Interference

Microwave Oven

BlueTooth

Microwave Oven

BlueTooth

Pow

er

Pow

er

The Industry’s ONLY In-Line High-Resolution Spectrum Analyzer


Benefits of CleanAir Technology

Self Healing and Optimizing

Forensics for Troubleshooting

Wireless Security

Policy Enforcement


Self Healing and Optimization

PERFORMANCE AIR QUALITY

Wireless LAN Controller

11

6

1

RRM

Channels 11, 6 and 1 Are Optimized for Maximum Performance and Minimum Interference





11

1

RRM

6

Channels 11, 6 and 1 Are Optimized for Maximum Performance and Minimum Interference

Interference on Channel 6. Air Quality Is Affected. RRM Is Browsing the List of Preferred Channels to Resolve Conflict…

11 6 1

Scanning Available Channels…





11

1

RRM

11 6 1 Changing to Channel 11

6 11

X Conflict Resolved. Information Is Being Relayed to RRM. Conflicting Channel Is Blocked from Future Use.



Persistent Device

Avoidance Self Learning to Increase Reliability

Event Driven

RRM CH 1 CH 1 CH 11 CH 1 Self Healing to Avoid Wi-Fi Degradation

Interference Aware RRM Maximizes Performance by Avoiding Interference


“RF Matters”


Q&A


  Cisco CleanAir solutions

  Farpoint Tech Note: Evaluating Interference in Wireless LANs: Recommended Practice (PDF; 220 KB)

  Farpoint Tech Note: Interference and Metro-Scale Wi-Fi Mesh Networks (PDF; 98 KB)

  Farpoint Tech Note: The Effects of Interference on Video Over Wi-Fi (PDF; 100 KB)

  Farpoint Tech Note: The Effects of Interference on VoFi Traffic (PDF; 88 KB)

  Farpoint Tech Note: The Invisible Threat: Interference and Wireless LANs (PDF; 83 KB)

  Farpoint Tech Note: The Effects of Interference on General WLAN Traffic (PDF; 88 KB)

  Protecting Wi-Fi Networks from Hidden Layer 1 Security Threats (PDF; 7 MB)

  RF Spectrum Policy: Future-Proof Wireless Investment Through Better Compliance

  20 Myths of Wi-Fi Interference

Links


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