D-Link DSL-604+ Introduction to 802.11b Wireless, Wireless LAN Basics, Radio Transmission, Range

DSL-604+ ADSL Ethernet Router User’s Guide

Introduction to 802.11b Wireless

The IEEE 802.11b standard is the most widely used standard for wireless LANs today. A wireless LAN (WLAN) is a cellular computer network that transmits data using radio signals instead of cables. WLAN technology is commonly used on home, small office and large corporate networks. WLAN devices have a high degree of mobility and flexibility that allow network to be quickly set up or dismantled and allow them to roam freely throughout the network.

Wireless LAN users can use the same network applications used on an Ethernet LAN. 802.11b adapter cards used on laptop and desktop computers support the same protocols as Ethernet adapter cards. For most users, there is no functional difference between a computer attached to a wired Ethernet LAN or a mobile 802.11b workstation except that hardware is not physically attached to the network. For most networks however, it may be desirable for mobile network devices to be able to link to the wired Ethernet LAN to use shared resources such as servers, printers or an Internet connection. The DSL-604+ unites Ethernet and 802.11b wireless private networks with an Internet connection. The DSL-604+ supports data rates of up to 22 Mbps for wireless operation when used in conjunction with other D-Link AirPlus devices.

D-Link Wireless LAN devices have earned a reputation for reliability, flexibility and value. D-Link offers a full range of IEEE 802.11b and IEEE 802.1a WLAN products including:

u802.11b and 802.11a Wireless Adapter cards for notebook computers

u802.11b and 802.11a Wireless PCI cards for desktop computers

u802.11b and 802.11a Wireless Access Points

uDual-band (802.11b plus 802.11a) Wireless Access Points

u802.11b and 802.11a Wireless Home Gateways

u802.11b and 802.11a Wireless ADSL Routers

Wireless LAN Basics

Some basic understanding of 802.11b wireless technology and terminology when is useful when you are setting up the Router or any wireless access point. If you are not familiar with wireless networks please take a few minutes to learn the basics.

Radio Transmission

WLAN devices use electromagnetic waves within a broad, unlicensed range of the radio spectrum to transmit and receive radio signals. When a wireless access point is present, it becomes a base station for the WLAN nodes in its broadcast range. WLAN nodes transmit digital data using FM (frequency modulation) radio signals. WLAN devices generate a carrier wave and modulate this signal using various techniques. In this way, digital data can then be superimposed onto the carrier signal. This radio signal carries data to WLAN devices within range of the transmitting device. The antennae of WLAN devices listen for and receive the signal. The signal is demodulated and the transmitted data extracted. The transmission method used by the access point is called Direct Sequence Spread Spectrum (DSSS) and operates in a range of the radio spectrum between 2.4GHz and 2.5GHz for transmission. DSSS is preferred method used on many 802.11b devices.

Range

Range should not be a problem in most homes or small offices. If you experience low or no signal strength in some areas, consider positioning the device in a location between the WLAN devices maintaining a roughly equal straight-line distance to all devices that need to access the Router through the wireless interface. Adding more 802.11b access points to rooms where the signal is weak can improve signal strength. Read the section about placement of the Router titled Location in the next chapter, Hardware Installation, for more information.

SSID

Wireless networks use an SSID (Service Set Identifier) to allow wireless devices to roam within the range of the network. Wireless devices that wish to communicate with each other must use the same SSID. Several access

5