11. Would the information be intercepted while transmitting on
air
？
WLAN features two-fold protection in security. On the hardware
side, as with Direct Sequence Spread Spectrum technology, it has
the inherent security feature of scrambling. On the software side,
WLAN series offer the encryption function (WEP) to enhance
security and Access Control. Users can set it up depending upon
their needs.
12. What is DSSS
？
What is FHSS
？
And what are their differences
？
Frequency-hopping spread-spectrum (FHSS) uses a narrowband
carrier that changes frequency in a pattern that is known to both
transmitter and receiver. Properly synchronized, the net effect is to
maintain a single logical channel. To an unintended receiver, FHSS
appears to be short-duration impulse noise. Direct-sequence
spread-spectrum (DSSS) generates a redundant bit pattern for
each bit to be transmitted. This bit pattern is called a chip (or
chipping code). The longer the chip is, the greater the probability
that the original data can be recovered. Even if one or more bits in
the chip are damaged during transmission, statistical techniques
embedded in the radio can recover the original data without-the
need for retransmission. To an unintended receiver, DSSS appears
as low power wideband noise and is rejected (ignored) by most
narrowband receivers.
13. What is Spread Spectrum
？
Spread Spectrum technology is a wideband radio frequency
technique developed by the military for use in reliable, secure,
mission-critical communication systems. It is designed to trade off
bandwidth efficiency for reliability, integrity, and security. In other
words, more bandwidth is consumed than in the case of narrowband
transmission, but the trade off produces a signal that is, in effect,
louder and thus easier to detect, provided that the receiver knows
the parameters of the spread-spectrum signal being broadcast. If a
receiver is not tuned to the right frequency, a spread –spectrum
signal looks like background noise. There are two main alternatives,
Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping
Spread Spectrum (FHSS).
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