Adsl Technology - D-Link DSL-G604T User Manual

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 the preferred method used on many 802.11b and 802.11g 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 Router in a location between the WLAN devices that maintains 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
points can be set up using the same SSID so that wireless stations can move from one location to another without
losing connection to the wireless network.
The DSL-G604T operates in Infrastructure mode. It controls network access on the wireless interface in its
broadcast area. It will allow access to the wireless network to devices using the correct SSID after a negotiation
process takes place. The DSL-G604T broadcasts its SSID so that any wireless station in range can learn the
SSID and ask permission to associate with it. Many wireless adapters are able to survey or scan the wireless
environment for access points. An access point in Infrastructure mode allows wireless devices to survey that
network and select an access point with which to associate.
It is important to understand the difference between the SSID and a BSSID (Basic Service Set Identifier) or
Preferred BSSID. The Preferred BSSID is defined by wireless stations to designate an access point used for
access to the wireless network. The Preferred BSSID is the MAC address of the access point. Therefore any
wireless stations (wireless clients) that use the DSL-G604T through the wireless interface must use its MAC
address for the Preferred BSSID. A wireless station that scans the network for available access points may
present the user with a choice of access points identified by their BSSID.

ADSL Technology

Asymmetric Digital Subscriber Line (ADSL) is a broadband technology that utilizes ordinary copper telephone
lines to enable high-speed digital data transmission and interactive multimedia applications for business and
residential customers.
ADSL greatly increases the signal-carrying capacity of copper telephone lines for faster downloads and more
reliable connectivity without interfering with regular telephone services. ADSL devices make it possible to enjoy
benefits such as high-speed Internet access without experiencing any loss of quality or disruption of voice/fax
telephone capabilities.
ADSL provides a dedicated service over a single telephone line operating at speeds of up to 8 Mbps downstream
and up to 640 Kbps upstream, depending on local telephone line conditions. A secure point-to-point connection
is established between the user and the central office of the service provider.
D-Link ADSL devices incorporate the recommendations of the ADSL Forum regarding framing, data format,
and upper layer protocols.
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