Watchguard Firebox X20E, Руководство пользователя

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About the Firebox X Edge e-Series Wireless.
236 Firebox X Edge e-Series
radiation pattern similar to a sphere that is squashed in the center. If the antenna points up, the gain is
largest in the horizontal direction and less in the vertical direction.
Signal attenuation
Signal attenuation refers to the loss of signal power. It can be caused by multi-path reflection. Multi-
path reflection occurs when RF signals that come to the receiver must move along more than one path
because of walls and other surfaces between the transmitter and the receiver. It changes based on the
phase at which the signals come. Signal strength can be increased or decreased by as much as 30dB.
To decrease the effect of multi-path reflection, the Firebox X Edge e-Series Wireless uses two antennas
spaced some distance apart. This decreases signal cancellation and allows the software to find the best
antenna to receive and transmit as conditions change.
Wireless clients usually have one antenna and are more sensitive to the effects of antenna location.
Because of this, the Firebox X Edge e-Series Wireless can receive signals from a wireless client even if
the client does not receive signals from the Firebox X Edge.
Channel data rate
Channel data rate changes with the modulation type, which changes based on conditions including
noise and the distance between transmitter and receiver. In general, the available data rates for an IEEE
802.11g/b device change from 1 Mbps in the worst conditions to 54 Mbps in the best conditions.