Презентации / 1-2 Wireless Intro
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Enterprise WLAN Design — Location
qGeneric guidelines for video, voice or data applications still apply.
qAP placement is now the MOST important
üMust take triangulation into consideration.
üEffective location requires at least three APs to detect signal.
üAP placement should be staggered
üAP density should be greater.
qCalibration of the RF environment is very important to increase accuracy
qAntennas should be positioned at less than 6 meters height.
Location Readiness
A point on floor map is location-
ready if:
§ min. of 4 AP’s are deployed
§ min. of 3 AP’s are within 21 meters (70
feet)
§ At least 1 AP placed in each of at least 3 surrounding quadrants
AP Placement Examples for Location
Poor AP placement and
coverage for location –
linear AP placement
Proper AP placement and
coverage for location –
staggered AP placement
with perimeter coverage
Big cells = low density
Smaller cells = more density
So, how can you cover this?
48 degree antenna angle
12m AP
21 degree seating pitch
A Radio Needs a Proper Antenna
As the frequency goes up, the radiating element gets smaller
Antennas are identified by color
Blue indicates 5 GHz
Black indicates 2.4 GHz
Orange indicates Both
Antennas are custom made for the frequency to be used. Some antennas have
two elements to allow for both frequencies in one antenna enclosure. Cisco
AP-3700/3600/2600/1600 use such antennas.
Directional antennas like this “Patch”
antenna radiate forward like placing
tin foil behind the light bulb or tilting
and directing the lamp shade
Note: Same RF energy is used but
results in greater range as it is
focused towards one direction, at the
cost of other coverage areas
Antenna placement
ØUse the maximum number supported
ØUse all same type of antenna’s on an AP
ØPosition all of them in the same orientation
ØAccess points with internal antennas are designed to be mounted horizontally
ØAntenna spacing is always a compromise on effects
üTarget for positioning antennas around ½ to 1 wave length apart*
ü*Results vary based on environment. Spacing on ½ wave length intervals has highest probability to provide best performance in multipath rich environment
üFor 2.4 GHz ½ wave length ~ 6.35 cm
üFor 5.2 GHz ½ wave length ~ 2.8 cm
receivers
transmitters
Types of antennas available
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Antenna Type |
Description |
Ideal Deployment |
Dipole
Monopole
360 degree coverage pattern |
Carpeted space environments, classrooms, hallways, |
Swivel or fixed |
conference rooms |
Long (dipole) or short (monopole) |
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Indoor/Outdoor Dual |
360°omni. |
Open office areas, hallways, conference rooms, outside |
Band Omni |
2.4 and 5 GHz |
areas |
Higher gain |
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Directional |
Focused beam |
Hallways, outside areas, on walls pointing inward to direct |
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High gain |
signals |
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Multi Mount Omnidirectional
360 degree pattern |
Areas with high ceilings, factory/warehouse floors |
Moderate gain |
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Easy placement |
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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
Low gain Omni radiates much like a bulb “360”