Linksys WRT54GR manual What is ISM band?, What is Spread Spectrum?

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Wireless-G Broadband Router with RangeBooster

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 (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.

Appendix A: Troubleshooting

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Frequently Asked Questions

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Contents Wireless- G How to Use This User Guide Copyright and TrademarksWord definition Table of Contents Appendix B Wireless Security Appendix a TroubleshootingCommon Problems and Solutions Frequently Asked Questions Appendix C Upgrading Firmware Appendix D Windows HelpRouter’s Back Panel List of Figures27 Wireless Tab Wireless MAC Filter Welcome IntroductionWhat’s in this User Guide? Wireless-G Broadband Router with RangeBooster Ad-Hoc versus Infrastructure Mode Planning Your Wireless NetworkSsid service set identifier your wireless network’s name Network TopologyPlanning Your Wireless Network Network Layout Network devices Back PanelRouter’s LEDs are located on the front panel Front PanelConnecting the Wireless-G Broadband Router with RangeBooster Connecting Your Network Devices Overview Password ScreenInternet Setup Setup Tab Basic SetupPPPoE Connection Type Router IP Time Setting DDNS.com Setup Tab Ddns16 Setup Tab MAC Address Clone Setup Tab MAC Address Clone17 Setup Tab Advanced Routing Setup Tab Advanced RoutingChanges to cancel your changes Wireless Tab Basic Wireless Settings20 Wireless Tab Wireless Security WEP Wireless Tab Wireless Security22 Wireless Tab Wireless Security PSK2 Radius Wireless MAC Filter Wireless Tab Wireless MAC FilterAdvanced Wireless Wireless Tab Advanced Wireless SettingsWireless-G Broadband Router with RangeBooster Firewall Security Tab FirewallInternet Filter Web FiltersAccess Restrictions Tab Internet Access Policy Internet Access PolicySecurity Tab VPN Passthrough 33 Internet Policy Summary To create an Internet Access policySingle Port Forwarding Applications and Gaming Tab Single Port Forwarding36 Applications and Gaming Tab Port Range Forward Applications and Gaming Tab Port Range ForwardingApplications & Gaming Tab Port Range Triggering Applications and Gaming Tab DMZPort Triggering Range Management Administration Tab ManagementBackup and Restore Log Administration Tab Log42 Administration Tab Diagnostics Administration Tab DiagnosticsAdministration Tab Firmware Upgrade Administration Tab Factory DefaultsStatus Tab Router Router InformationInternet Connection Status Tab Local Network Status Tab Wireless NetworkAppendix a Troubleshooting Common Problems and SolutionsNeed to set a static IP address on a PC Wireless-G Broadband Router with RangeBooster Open a command prompt. For Windows 98SE and Me TCP Application Start and End Protocol IP Address EnabledCan’t get the Internet game, server, or application to work Wireless-G Broadband Router with RangeBooster Need to upgrade the firmware To start over, I need to set the Router to factory defaultFirmware upgrade failed, and/or the Power LED is flashing My DSL service’s PPPoE is always disconnectingPower LED keeps flashing Where is my SecureEasySetup button? Frequently Asked QuestionsWhere is the Router installed on the network? Is IPSec Pass-Through supported by the Router?Does the Router support ICQ send file? What is Network Address Translation and what is it used for?How can I block corrupted FTP downloads? What are the advanced features of the Router? What is DMZ Hosting?What is the Ieee 802.11g standard? Is the Router cross-platform compatible?What Ieee 802.11g features are supported? What is the Ieee 802.11b standard?What Ieee 802.11b features are supported? What is ad-hoc mode?What is ISM band? What is Spread Spectrum?What is DSSS? What is FHSS? And what are their differences? What is a MAC Address? What is WEP?How do I reset the Router? How do I resolve issues with signal loss?Appendix B Wireless Security Security PrecautionsSecurity Threats Facing Wireless Networks Appendix B Wireless Security Wireless-G Broadband Router with RangeBooster Appendix C Upgrading Firmware Figure C-1 Upgrade FirmwareAppendix D Windows Help Shared ResourcesNetwork Neighborhood/My Network Places Windows 2000 or XP Instructions Windows 98SE or Me InstructionsFigure E-4 MAC Address Filter List For the Router’s Web-based UtilityAppendix D Glossary Wireless-G Broadband Router with RangeBooster Wireless-G Broadband Router with RangeBooster Wireless-G Broadband Router with RangeBooster Wireless-G Broadband Router with RangeBooster Appendix G Specifications ModelStandards Storage Temp Operating HumidityStorage Humidity Limited Warranty Appendix H Warranty InformationFCC Statement Appendix G Regulatory InformationWireless-G Broadband Router with RangeBooster Wireless-G Broadband Router with RangeBooster Wireless-G Broadband Router with RangeBooster Wireless-G Broadband Router with RangeBooster Wireless-G Broadband Router with RangeBooster Appendix J Contact Information
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