Linksys WRT54GX manual What is ISM band?, What is Spread Spectrum?

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Wireless-G Broadband Router with SRX

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 802 GHz .11g Wireless- G Copyright and Trademarks How to Use This User GuideWord definition Table of Contents Appendix B Wireless Security Appendix a TroubleshootingCommon Problems and Solutions Frequently Asked Questions Router’s Back Panel Router’s Reset Button27 Port Services Welcome IntroductionWhat’s in this Guide? Wireless-G Broadband Router with SRX Network Layout Planning Your Wireless NetworkAd-Hoc versus Infrastructure Mode Network TopologyPlanning Your Wireless Network Network Layout Back Panel Getting to Know the Wireless-G Broadband RouterDMZ Front PanelOverview Connecting the Wireless-G Broadband RouterPassword Screen Configuring the Wireless-G Broadband RouterInternet Setup Setup Tab Basic SetupStatic IP Connection Type Pptp Connection Type Packet a unit of data sent over a network Network SetupNetwork Address Server Settings Dhcp 12 Setup Tab Ddns Setup Tab Ddns13 Setup Tab MAC Address Clone Setup Tab MAC Address Clone14 Setup Tab Advanced Routing Setup Tab Advanced Routing16 Wireless Tab Basic Wireless Settings Wireless Tab Basic Wireless SettingsWPA Radius Wireless Tab Wireless SecurityWEP 20 Wireless Tab Wireless MAC Filter Wireless Tab Wireless MAC Filter22 Wireless Tab Advanced Wireless Settings Wireless Tab Advanced Wireless Settings23 Security Tab Firewall Security Tab FirewallTo create an Internet Access policy Access Restrictions Tab Internet AccessUrl the address of a file located on the Internet Ftp a protocol used to transfer files over a TCP/IP networkApplications and Gaming Tab Port Triggering Applications and Gaming Tab Port Range ForwardApplications and Gaming Tab UPnP Forwarding Applications and Gaming Tab DMZUPnP Forwarding Snmp Administration Tab ManagementAdministration Tab Diagnostics Administration Tab LogUPnP Administration Tab Firmware Upgrade Administration Tab Factory DefaultsStatus Tab Router Administration Tab Config ManagementIsp your internet provider 39 Status Tab Local Network Status Tab Local NetworkEncryption encoding data transmitted in a network Status Tab WirelessSystem Performance Status Tab System PerformanceWireless-G Broadband Router with SRX Common Problems and Solutions Appendix a TroubleshootingNeed to set a static IP address on a PC For Windows 98SE, Me, 2000, and XP 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 SRX Firmware upgrade failed, and/or the Power LED is flashing To start over, I need to set the Router to factory defaultMy power LED will not stop flashing Need to upgrade the firmwareCannot connect to the Internet How do I turn on SRX on my router? My wireless-G speed seems to be slowDoes the Router support IPX or AppleTalk? Frequently Asked QuestionsWhere is the Router installed on the network? Is IPSec Pass-Through supported by the Router?How can I block corrupted FTP downloads? Is the Router cross-platform compatible? What is DMZ Hosting?What are the advanced features of the Router? Will the Router function in a Macintosh environment?What is infrastructure mode? What is the Ieee 802.11g standard?What Ieee 802.11b features are supported? What is ad-hoc mode?What is Spread Spectrum? What is ISM band?What is DSSS? What is FHSS? And what are their differences? How do I resolve issues with signal loss? What is WEP?What is a MAC Address? How do I reset the Router?Security Precautions Appendix B Wireless SecuritySecurity Threats Facing Wireless Networks Appendix B Wireless Security Wireless-G Broadband Router with SRX Appendix C Upgrading Firmware Figure C-1 Upgrade FirmwareShared Resources Appendix D Windows HelpNetwork Neighborhood/My Network Places Windows 98SE or Me Instructions Figure E-1 IP Configuration ScreenFor the Router’s Web-based Utility Windows 2000 or XP InstructionsAppendix F Glossary Wireless-G Broadband Router with SRX Wireless-G Broadband Router with SRX Wireless-G Broadband Router with SRX Wireless-G Broadband Router with SRX Wireless-G Broadband Router with SRX Model Appendix G SpecificationsStandards Storage Temp Limited Warranty Appendix H Warranty InformationFCC Statement Appendix I Regulatory InformationFrance Appendix J Contact Information
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