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WAP4410N Wireless-N Access Point with Power Over Internet 70
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Q. What is Spread Spectrum?
Spread Spectrum technology is a wideband radio frequency technique
developed by the military for use in reliable, secure, mission-critical
communications 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).
Q. 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, 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.
Q. 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, the WLAN series offers a variety of wireless
security methods to enhance security and access control. Users can set it up
depending upon their needs.
Q. Can Cisco wireless products support file and printer sharing?
Cisco wireless products perform the same function as LAN products. Therefore,
Cisco wireless products can work with NetWare, Windows NT/2000, or other LAN
operating systems to support printer or file sharing.