User's Manual

Wistron
NeWeb
Wistron NeWeb Corporation
20 Park Avenue II, Hsinchu Science Park, Hsinchu 308, Taiwan, R.O.C.
Phone: [phone] Fax: [phone]
Website: www.wneweb.com
Wistron NeWeb Confidential Document
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Appendix A: FAQ about WLAN
1. Can I run an application from a remote computer over the wireless network?
This will depend on whether or not the application is designed to be used over a network.
Consult the application’s user guide to determine whether it supports operation over a
network.
2. Can I play computer games with other members of the wireless network?
Yes, as long as the game supports multiple players over a LAN (local area network).
Refer to the game’s user guide for more information.
3. 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).
4. 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.