Hi,
It looks like you are referring to the below link:
http://www.cisco.com/c/en/us/td/docs/wireless/technology/ap1000/deployment/guide/hah_apdg/dg10ic.pdf
If so, this just simply means that the client used for testing has a transmit power of 15dBm or more and a no gain (zero gain) antenna.
Best Regards,
WiFi Trainers (www.wifitrainers.com)
Simplifying WiFi
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