Summary of DSL technology

However DSL has grown on high-speed analog signals (usually represented by sinusoidal waves) and is not related to numbers.The S (subscriber) refers to you or your company when renting a DSL line from a telecommunications service provider.The word L (line) means that this is a line (also called a circuit) on the outside of the telephone cable from a telecommunications service provider, like a cable for a phone that you are still using every day. .Most of the use of DSL circuits is to physically connect you to the Internet, so you are always on the network.This connection also allows you to link to other places (eg office offices) over the Internet.With DSL access, you don't need to use regular modem, but you need another device, which is DSL modem.

One of the reasons for DSL being useful is that it offers significant speed on a pair of copper wires.Most homes and offices have built-in pairs of cables for regular phones.Therefore DSL does not require dedicated new cables.Because DSL is designed to use normal copper cables, it does all the tasks from your office to the center of the telecom service provider and this device is called a DSLAM (Digital Subscriber Line Access Multiplexor). .Using separate lines is called dry wire.When combining phone lines with DSL on the same pair of wires, it is called DSL distribution on wet wires.You can have phone conversations simultaneously with using DSL, sharing entertainment on a pair of wires.Once this signal is transmitted to the DSLAM, the voice part is separated and goes to the public telephone switch (PSTN), the data on the DSL is sent to the Internet service provider.There is a distance limit for DSL.Generally the farther away from the center of the telecom service provider the lower the speed.If the DSLAM is located at the office building for rent, the distance is no longer a problem as it is connected to the telecommunications service provider through their device, and the DSL circuit only needs to be connected from the DSLAM right in the building. to your office.ADSL (Asymmetrical DSL) is mostly used for Internet access from families.Circuit capacity from the Internet home (down stream) is larger than the opposite direction (up flow).This is suitable for home users who need to receive more information (graphics, sound, animations) than sending information online (typing and hovering).SDSL (Symmetrical DSL) is the type used by most business operations, needing to send and receive significant amounts of information.The circuit capacity is the same for both directions.Circuit capacity affects quickly downloading information and sending data elsewhere.If you work with image files, you need a larger capacity DSL circuit than when sending text files.Capacity should also be larger if many people use it at the same time.(You can connect DSL to LANs for sharing in the office.) Normal capacity is 128Kbps, average speed is 256Kbps, 512Kbps, 768Kbps and large capacity circuits are usually 1Mbps, 1.5Mbps.You can hear about other types of DSLs, high bit-rate DSLs are 1.544Mbps and use two or three pairs of wires instead of one pair.IDSL (ISDN DSL) has the same speed of 128Kbps or 144Kbps as the Integrated Services Digital Network (ISDN) service.DSL Lite (also called G-Lite) is the lowest speed model of ADSL.RADSL is Rate Adaptive DSL adjusts the transmission rate according to signal quality.VDSL is Very High Speed ​​DSL (12.9 to 52.8Mbps downstream and 1.5 to 2.3Mbps upstream).

Why use DSL?

Most agencies and individuals who have been using the Internet for years have begun connecting to the Internet by using a dial-up connection.The highest speed achieved by this method is now 56Kbps, but in practice the speed is usually lower, depending on the phone line status.Save time: One reason to switch to DSL is that you don't have to wait long to download from the Internet.When Web radio enhances audiovisual features, having a larger capacity to receive data in a shorter time is the most important reason.

Saving money: Many offices still rent separate phone lines from phone companies for about $ 30 a month for each user to dial the Internet connection. These lines pay regardless of whether they are used or not, plus the minutes used. A DSL line of $ 150 / month can replace 10 outgoing telephone lines and can share with ten users. The price of regular DSL lines can range from 40USD / month to hundreds of USD or more depending on speed and service level guarantee. If you use the above wet connection at home and have both a telephone line and a DSL distributed by your DSL service provider, the total cost may be lower because you do not need to separate a phone line and a cord. Other for dial up Internet connection. More responsive: Many of your customers are able to enter the network immediately and expect you to do the same. With DSL you can receive email as soon as the Internet service provider delivers it, allowing you to respond to the sender quickly. This can also make you take advantage of business opportunities before it passes.

In addition, you can consider setting up your own Web breeding station, providing more information to customers.Experiment with new technologies: Having DSL you get the capacity needed to test new technologies like Web cam, which allows you to organize video conferences while sharing documents with other people connected to the Internet (and install television sets together).Similar applications can enhance communication with customers or between people working in the same company in different locations.There is even no Web cam for video conferencing, you can test voice over DSL (VoDSL) - similar to voice over IP (VoIP), which is now an interesting topic.You need the right phone for this, it can convert the voice into a suitable format for streaming on the Internet.Applicability in Vietnam DSL technology has been applied by some units in Vietnam to its network on separate pull copper cables, allowing for high-bandwidth solutions instead of using fiber-optic cables, thus reducing costs. .Meanwhile, the deployment of DSL over the network of telecommunication companies has no practical benefit because the capacity of these units is too high compared to the savings from DSL, according to an evaluation of a company. Trading in these devices.Therefore, although highly appreciated in other countries, such as Singapore using ADSL to bring Internet speed of 2Mbps to family subscribers, the ability to use DSL service in Vietnam is very limited, except in case of self-service by My own cable.Currently DSL products of RAD firms, Pairgain and Pandatel have been provided through agents in Vietnam market.Refer to Pandatel technical specifications: with 0.6mm diameter copper wire, it allows to provide 128Kbps and 2Mbps bandwidth at 11Km and 6Km respectively.