Planet Technology Wireless USB Adapter WNL-U553 - Manual (Page 24)

What is AES?
AES (Advanced Encryption Standard) is a chip-based encryption
method of new generation and has been incorporated into the
newly-approved security standard 802.11i. It supports 128, 192 and
256-bit encryption key length and adopts Rijndael algorithm. It is
widely believed it is impossible to crack AES.
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
transmitters and receivers. 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.
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).