Sunday, October 11, 2009

RF Power Terminology

dB - attenuation/amplification of the power level - expressed as the base 10 logarithm of the ratio of the power of two signals, as shown here:
  • dB = 10 x Log10 (P1/P2)
dBi - power gain rating of antennas
dBm - uses same calculations as dB, but has a reference value of 1mW.  Can also describe receiver sensitivity in -dBm.

Data networks: AP separation of 120-130 feet
Voice networks: cell edge at -67dBm, 2 non overlapping APs at an RSSI +35
                             baseline power of 35-50mw
                             requires 15% more APs than a 100mW deployment

APs have an aggregate throughput less than the data rate because the 802.11 provides a reliable transport mechanism that ACKs all packets, thereby halving the throughput on the channel.

1 comment:

  1. I cannot believe I never took the time to look over your blog, this is great stuff and although half of it makes my head hurt, I'm sure I'll be visiting often. Best of luck on your quest for CCIE Wireless!