Cisco Cisco Aironet 3500p Access Point 정보 가이드
When looking at the UNII−1 band 5150−5240 MHz (channels 36−48), you can see that the
primary or dedicated (licensed use) for this spectrum is for the Aeronautical Radio Navigation
service and fixed satellite use, applications such as Microwave Landing systems and outdoor
communications.
primary or dedicated (licensed use) for this spectrum is for the Aeronautical Radio Navigation
service and fixed satellite use, applications such as Microwave Landing systems and outdoor
communications.
When the UNII−1 frequencies are used indoors with limited RF power, the FCC permits these
frequencies to be used for unlicensed Wi−Fi because such devices can co−exist with limited
interference provided the Peak RF power and the Power Spectral Density (PSD) are kept
within acceptable levels.
frequencies to be used for unlicensed Wi−Fi because such devices can co−exist with limited
interference provided the Peak RF power and the Power Spectral Density (PSD) are kept
within acceptable levels.
On October 25th 2011, the FCC Office of Engineering and Technology Laboratory Division
released a paper about the testing of transmitters with Multiple Outputs in the same band.
These new guidelines help to reduce potential interference and apply to Smart Antenna
systems and all Wireless LAN products utilizing Multiple Input Multiple Output (MIMO)
technology regardless of vendor.
released a paper about the testing of transmitters with Multiple Outputs in the same band.
These new guidelines help to reduce potential interference and apply to Smart Antenna
systems and all Wireless LAN products utilizing Multiple Input Multiple Output (MIMO)
technology regardless of vendor.
This FCC bulletin was released to address how manufacturers such as Cisco must comply
with the new guidelines. These guidelines are available at these FCC URLs:
with the new guidelines. These guidelines are available at these FCC URLs:
http://apps.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm?id=49466&switch=P
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http://apps.fcc.gov/kdb/GetAttachment.html?id=38670
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The take−away is that the FCC has introduced additional clarification about the method
manufacturers must comply with PSD limits.
manufacturers must comply with PSD limits.
From the FCC paper, directional gain calculations can be done using this method:
Directional Gain CalculationsIn the re−occurring case of N transmit antennas, each with
the same directional gain GANT dBi driven by N transmitter outputs of equal power,
directional gain is to be computed as follows:
the same directional gain GANT dBi driven by N transmitter outputs of equal power,
directional gain is to be computed as follows:
If any transmit signals are correlated with each other, Directional gain = GANT + 10
log(N) dBi
log(N) dBi
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If all transmit signals are completely uncorrelated with each other, Directional gain =
GANT
GANT
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From the FCC paperCorrelation between signals transmitted from different antennas can