Appendix B Planning Your Wireless Network

Instant WirelessTM Series

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 transmis- sion, 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.

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 fea- ture of scrambling. On the software side, the WLAN series offers the encryp- tion function (WEP) to enhance security and access control. Users can set it up depending upon their needs.

Can Instant Wireless products support file and printer sharing?

Instant Wireless products perform the same function as LAN products. Therefore, Instant Wireless products can work with NetWare, Windows NT/2000, or other LAN operating systems to support printer or file sharing.

I am using 802.11b-compliant wireless equipment but still cannot connect to my wireless network.

Verify that you are using the same IP domain as that of your wireless network.

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Appendix B: Planning Your Wireless Network

Network Topology

A wireless LAN is exactly like a regular LAN, except that each network device in the LAN uses wireless technology to connect to the network. Computers in a wire- less LAN must be configured to share the same radio channel.

Wireless components provides LAN access for wireless network devices. An inte- grated wireless and wired LAN is called an Infrastructure configuration. A group of wireless users and an access point compose a Basic Service Set (BSS). Each PC equipped with a wireless adapter in a BSS can talk to any computer in a wired LAN infrastructure.

An infrastructure configuration extends the accessibility of a wireless user to a wired LAN, and doubles the effective wireless transmission range for wireless PCs. Since the access point is able to forward data within its BSS, the effective transmission range in an infrastructure LAN is doubled.

The use of a unique ID in a Basic Service Set is essential.

The Wireless LAN Infrastructure configuration is appropriate for enterprise-scale wireless access to a central database, or as a wireless application for mobile users.

Roaming

Infrastructure mode also supports roaming capabilities for mobile users. More than one BSS can be configured as an Extended Service Set (ESS). This continu- ous network allows users to roam freely within an ESS. All wireless PCs within one Extended Service Set must be configured with the same SSID.

Selecting a feasible radio channel and optimum access point position is recom- mended. Proper access point positioning combined with a clear radio signal will greatly enhance performance.