March Networks GW-DS150N, Manual

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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).
14. What is WMM?
Wi-Fi Multimedia (WMM), a group of features for wireless networks that improve the user experience
for audio, video and voice applications. WMM is based on a subset of the IEEE 802.11e WLAN QoS
draft standard. WMM adds prioritized capabilities to Wi-Fi networks and optimizes their performance
when multiple concurring
applications, each with different latency and throughput requirements, compete for network
resources. By using WMM, end-user satisfaction is maintained in a wider variety of environments
and traffic conditions. WMM makes it possible for home network users and enterprise network
managers to decide which data streams are most important and assign them a higher traffic
priority.
15. What is WMM Power Save?
WMM Power Save is a set of features for Wi-Fi networks that increase the efficiency and flexibility
of data transmission in order to conserve power. WMM Power Save has been optimized for mobile
devices running latency-sensitive applications such as voice, audio, or video, but can benefit any