www.networks.pe análises de site para desempenho de wireless 802.11 jim.davis2@flukenetworks.com...
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www.networks.pe
Análises de site para desempenho de wireless 802.11
Jim.Davis2@flukenetworks.com
Regional Sales Director
Latin America
www.networks.pe
• Wireless basics– What do we need to make it work– What power levels do we want– When does interference start
• Site Survey 1 – Office Environment– Freeware– Paid solution– Internal laptop solution
• Site Survey 2 – Residential Enviroment– Paid solution– iPhone test survey
• Site Survey 3 – Campus Enviroment– Overlay network for event
Agenda
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The Death of Cabling?
Just a few Centimeters and no more Wired Network!!
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What do we need for wireless to work?
• Signal Strength• Low interference• Limited number of users• A Good wan Link
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Why Survey?• Signal propagation is hard to predict• Interference is impossible to predict• Walls, doors, elevator shafts, people, and other
obstacles offer varying degrees of attenuation• Testing solves this• It’s absolutely necessary to perform a wireless site
survey…– To determine how many APs– To determine placement of those APs– To determine the channel plan– To determine to power settings– To determine which antennas to use
AirMagnet Confidential
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Comparación en tamano de una onda 2.4 GHz contra una de 5GHz
AirMagnet Confidential
7
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Comparación de Atenuación entre Ondas RF
AirMagnet Confidential 9
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Que es Multipath?
Multipath ocurre cuando las señales de RF rebotan en objetos y se reciben fuera de fase en el receptor.
AirMagnet Confidential
11
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Perdida de Señal RF en el Espacio Libre
AirMagnet Confidential 12
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11n 11ac ph 1 11ac ph 2+
Modulation BPSK, QPSK, 16, 64 QAM
+ 256 QAM
Channel widths 20MHz, 40MHz + 80MHz + 160MHz
MIMO optionalMIMO minimum
4x42x2
8x81x1
8x81x1
MIMO available 3x3 3x3 4x4, 8x8
MIMO user mode Single-user Single-user Multi-user
Bands 2.4, 5 5 5
Operating Mode Mixed HT, Greenfield Mixed VHT Mixed VHT
Beam forming Optional, Proprietary (implicit feedback)
Optional, Standardized (explicit Rx > Tx feedback)
Optional, Standardized (explicit Rx > Tx feedback)
Aggregated data units Optional Mandatory Mandatory
PHY Data Rate (3x3) 450 Mbps 1300 Mbps 2,600 Mbps(6,933 Mbps for 8x8)
11ac Major changes from 11n
11ac also introduces : RTS/CTS extensions: stronger clearance requirements for secondary channels; available bandwidth (channel) indication in CTS
What does it bring to the user?
• Higher Rates
• 80/160 MHz channels, 256 QAM (up to 33% performance improvement), up to 8x8 MIMO, Multi-User MIMO,
mandatory data unit aggregation
• More User Capacity
• Higher Rates = Less airtime needed per User
• Compatibility with 802.11a/n at 5 GHz
• and most APs support dual-band and 802.11b/g/n at 2.4
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Traspaso de Canales 2.4 Ghz
AirMagnet Confidential 16
100% 78% 55%
33% 9%
0%
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11ac Channel allocation – 5GHz
From Andrew vonNagy’s RevolutionWifi revolutionwifi.blogspot.com
• 80 MHz wide channels allow for 5 non-overlapping channels in the U.S. and 5 in the UK/EU (channels 149 and higher require light licensing for outdoor use only) when DFS is used, but only 2 channels in the U.S. and 1 in UK/EU without DFS.
• 160 MHz wide channels allow for 1 non-overlapping channel in the U.S. and 2 in the UK/EU, with DFS being mandatory for their use in all circumstances.
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Niveles de Señal en dBm Recomendados
Velocidad de
Transmisión
2.4 GHz
Umbral de Recepción
2.4 GHz
Umbral para Trafico VoIP
5 GHz
Umbral de Recepción
54 -61 -56 -58
36 -63 -58 -63
24 -67 -62 -67
12/11 -72 -67 -72
6/5.5 -79 -74 -75
2 -81 -76 N/A
1 -84 -79 N/A
AirMagnet Confidential
18Source: Cisco
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Elimina Interferencia entre Canales
AirMagnet Confidential 21
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Fuentes Comunes de Interferencia que afectan a Redes 802.11
AirMagnet Confidential
22
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Spectrum Analyzer
AirMagnet Confidential 23
Potencia Promedio
Potencia Máxima Actual
Potencia Maxima
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Three Bears Guide to Wifi
Too Much Signal Strength - Interference
Not enough Signal Strength –Slow connections
Just Right
http://jility.wordpress.com/2013/06/04/and-the-three-bears/
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Site Survey Tools- Wheeled Cart so I
don’t have to carry PC- Tape Measure – for
Map Scale- Spectrum Analyzer
card on left side of laptop
- Dual antennas on right side - One for passive- One for active
survey- Not Shown
- InSSIDer software- iPhone
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Detail of 5GHz coverage filtered on Authorized guest – better
overlap
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Coverage area for one AP – do you really want to give free wifi to your neighbors?
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An Outdoor Campus Surveyboth permanent and temporary
Wifi set up-Just Right-
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There is signal in the place we want it, but it is below what we want
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• A Site Survey is Mandatory for Acceptable Wifi performance
• Some tools are no adequate for this such as the internal computer or iPhone power meter
• Freeware can do the trick if you know what you are doing and are flexible on the documentation
In Conclusion
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Jim DavisSales Director Latin America
Jim.Davis2@FlukeNetworks.com
http://es.FlukeNetworks.com
Alvaro CayoRep. Fluke Networks en PERU
Alvaro.Cayo@Networks.pe
http://Networks.pe
Thank You!Gracias!
Obrigado!
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