Linksys WPC54GX4 manual What is roaming?, What is ISM band?, What is Spread Spectrum?

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Wireless-G Notebook Adapter with SRX400

What is roaming?

Roaming is the ability of a portable computer user to communicate continuously while moving freely throughout an area greater than that covered by a single access point. Before using the roaming function, the workstation must make sure that it is the same channel number with the access point of dedicated coverage area.

To achieve true seamless connectivity, the wireless LAN must incorporate a number of different functions. Each node and access point, for example, must always acknowledge receipt of each message. Each node must maintain contact with the wireless network even when not actually transmitting data. Achieving these functions simultaneously requires a dynamic RF networking technology that links access points and nodes. In such a system, the user’s end node undertakes a search for the best possible access to the system. First, it evaluates such factors as signal strength and quality, as well as the message load currently being carried by each access point and the distance of each access point to the wired backbone. Based on that information, the node next selects the right access point and registers its address. Communications between end node and host computer can then be transmitted up and down the backbone.

As the user moves on, the end node’s RF transmitter regularly checks the system to determine whether it is in touch with the original access point or whether it should seek a new one. When a node no longer receives acknowledgment from its original access point, it undertakes a new search. Upon finding a new access point, it then re-registers, and the communication process continues.

What is ISM band?

The FCC and their counterparts outside of the U.S. have set aside bandwidth for unlicensed use in the ISM (Industrial, Scientific and Medical) band. Spectrum in the vicinity of 2.4 GHz, in particular, is being made available worldwide. This presents a truly revolutionary opportunity to place convenient high-speed wireless capabilities in the hands of users around the globe.

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).

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

Appendix A: Troubleshooting

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Frequently Asked Questions

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Contents User Guide Word definition How to Use This User GuideCopyright and Trademarks Table of Contents Adapter’s LEDs Setup Wizard’s Welcome Screen10 Import a Profile Welcome IntroductionWhat’s in This User Guide? But what does all of this mean?Introduction What’s in This User Guide? Network Topology Planning Your Wireless NetworkRoaming Topology the physical layout of a networkNetwork Layout LED Indicators Getting to Know the Wireless-G Notebook Adapter with SRX400Green. The LED lights up when the Adapter is powered on Adapter is transmitting or receiving dataOn the Welcome screen, you have the following choices Starting the Setup WizardInsert the Notebook Adapter Screen Available Wireless Network Screen Setting Up the AdapterWEP Key Needed for Connection Setting Up the Adapter with an Available NetworkWPA-Personal Needed for Connection 10 Available Wireless Network Screen Setting Up the Adapter with Manual Setup12 Wireless Mode Screen Click Next to continue or click Back to change any settingsWEP 17 Wireless Security WPA2 Personal Screen EAP-TLS Radius 22 Confirm New Settings Screen Accessing the Wireless Network Monitor Using the Wireless Network MonitorWireless Network Status screen Link Information ScreensMore Information Wireless Network Status Screen Wireless Network StatusProfile Wireless Network StatisticsSite Information Site SurveyUsing the Wireless Network Monitor Site Survey Profiles Screen Profiles12 Create a New Profile Creating a New Profile14 Available Wireless Network Screen 16 WPA-Personal Needed for Connection 20 Network Settings Screen 21 Wireless Mode Screen 23 Wireless Security Screen 26 Wireless Security WPA2 Personal Screen 27 Wireless Security WPA Enterprise Using EAP-TLS Screen 29 Wireless Security Radius Using EAP-TLS Screen 32 Congratulations Screen Common Problems and Solutions Appendix a TroubleshootingFrequently Asked Questions Wireless-G Notebook Adapter does not work properlyWhat is the Ieee 802.11g standard? What is the Ieee 802.11b standard?What Ieee 802.11b features are supported? What Ieee 802.11g features are supported?What is ISM band? What is roaming?What is Spread Spectrum? What is DSSS? What is FHSS? And what are their differences?What is RADIUS? What is WEP?What is WPA? Figure B-3 Windows XP Wireless Configuration Icon Select Use Linksys Wireless Network MonitorFigure B-4 Available Wireless Network Figure B-6 Network Connection Wireless Security You are now connected to your wireless networkSecurity Threats Facing Wireless Networks Appendix C Wireless SecuritySecurity Precautions Appendix C Wireless Security Wireless-G Notebook Adapter with SRX400 Network Neighborhood/My Network Places Appendix D Windows HelpShared Resources Appendix E Glossary Wireless-G Notebook Adapter with SRX400 Wireless-G Notebook Adapter with SRX400 Wireless-G Notebook Adapter with SRX400 Wireless-G Notebook Adapter with SRX400 Model Appendix F Specifications20dBm for Wireless-B/19dBm for Wireless-G Limited Warranty Appendix G Warranty InformationFCC Statement Appendix H Regulatory InformationWireless-G Notebook Adapter with SRX400 Wireless-G Notebook Adapter with SRX400 Wireless-G Notebook Adapter with SRX400 Wireless-G Notebook Adapter with SRX400 Dual-Band Wireless Access Point Linksys Appendix I Contact Information
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