What is Digital Subscriber Line ( DSL)?

Digital Subscriber Line ( DSL)

The development of the internet very quickly since the existence of the World Wide Web not only brought changes to the dissemination of information but also bring changes to the telecommunications infrastructure. But the speed of the increase of the number of internet users and the number of streams of data (information) faster than the development of the telecommunications infrastructure. With the growing number of information and data to be accessed form especially with multimedia is increasingly degrading demands for speed data access and informasi.

For a company will speed high data communication is indispensable for implementation on real-time multimedia applications such as video conferencing, relationship with branch offices, and other information services. To get a better quality then the diberikanlah solution with the ISDN (Integrated Service Digital Network). 

With digital technology the speed of data transmission can be done up to 64 Kbps for each channel, because basic ISDN can provide two canals then overall could have obtained access speed up to 128 Kbps. However, the main constraint of ISDN technology this is it needs a new telecommunications network. So not everyone can enjoy the advantages of this technology. In Indonesia there are telecommunications services that use this technology, namely the pasopati but this new limited services in several major cities.

Many of the variety used by Telecom operators to provide broadband access services to customers. From the media used, can be distinguished into two wireline technology (cable) and wireless technology (without cable). From wireline technology category can be used with DSL (Digital Subscriber Line), cable modem, HFC, optical. While the wireless category can take advantage of wireless LAN technology, BWA (Broadband Wireless Access) as well as the latest technology WiMAX (Worldwide Interoperability for Microwave Access).

With a variety of solutions above, some operators utilizing DSL technology (cable) and BWA (for wireless). For the incumbent telecommunications operator in a country, e.g. TELKOM for Indonesia which has presented cable about 6 million line will then utilise the DSL technology in order to update the enhanced physical network to transmit high speed data to the customer. As for the new operator is very difficult and expensive when deploying broadband network with DSL. Alternative harness wireless technology (BWA). With the birth of the newest wireless technology (WiMAX) then it can be used as a substitute or alternative to transmit broadband services to the customer.

When viewed from its market segment, between WiMAX and DSL have in common that is equally devoted to the MAN (Metro Area Network) where the distance to the customer about 10 km. 

Then comes the thought to keep using the existing infrastructure in order to build a high speed connection, based with the expensive new investments and the magnitude of the demand the need for quick access. One solution is with DSL (Digital Subscriber Line) which is a new technology. 

Subsriber digital Line (DSL) is a technology access with a special device at the central office and the customer that allows transmission of broadband through copper wires, this technology is often referred to by the term technology a shot or injection technology examples of operators that have been rolling out DSL in Indonesia are PT TELKOM. The product named SPEEDY. Regular phone wires so that there can be used to deliver a large amount of data and high speed. The phone using only the most capable frequency transmitted by copper wires. While DSL utilizing more frequency with share them (splitting), higher frequencies for data and a lower frequency for voice and fax. The distance the wearer to the CO determines the speed of DSL. The more users, the distance was much lower speed. 

Seen from the technical side of DSL technology uses packet data base while voice communication-based connections (circuit-switch). For connection-based data communications, the connection with a certain bandwidth width must be maintained even though there is no data passes. For voice communications for a short time unused is not so problematic, but for a long data communications will squander the resources owned by the PSTN. While data communication based package will allow optimum use of bandwith, because it can be used for more than one connections efficiently and economically.

DSL uses standard phone cord work made of copper telephone wire, the current type is already connected many and widely available to homes or offices. DSL technology brings both digital as well as analog signals on one cable. Digital signals to analog signals while data communication for the sound of the phone used halnya seperti now referred to as POTS (Plain Old Telephone System). The ability to separate voice and data signals is an advantage. DSL will connect and carry digital signals for data communication and works by using a special modem (DSL modem) to read (encode) such data and then send it via an unused frequency on the phone cord such. 

Utilizing high frequency DSL to send data and low frequency to channel the voice of/faximili. DSL became important and becomes a choice, at the time the user begins to seek the access speed to the internet connection. Without having to be dizzy and tired of waiting for bermenit - menit just to open a page of the internet let alone can enjoy multimedia services over the internet, such as watching the video service, video conferencing (camera) or other online service and the price could be cheaper Network PSTN (Public Switch Telephone Network) designed for voice communication that only a short berlangsung about three to five minutes.

Because of this then the same connection can be used alternately so as not to penyediaan the phone connection is required just as much with the number of telephone channels. But for data communication is generally the customer uses the time old lebih, especially with the existence of the internet it, then consequently the success rate of connection is experiencing a decline since majority of telephone lines used in the period the old.

Development of traffic very quickly this will overload the public telephone network (PSTN). There are two options that can be taken on the telecommunications service provider to resolve these things the first is improving the PSTN network to handle voice and data komunikasi demand increased and the latter move then litas data to a separate network designed specifically for data communication. Seen from the technical side of DSL technology uses packet data base while voice communication-based connections (circuit-switch).

For connection-based data communications, the connection with a certain bandwidth width must be maintained even though there is no data passes. For voice communications for a short time unused is not so problematic, but for a long data communications will squander the resources owned by the PSTN. While data communication based package will allow optimum use of bandwidth, because it can be used for more than one connection scar efficiently and economically. 

Which is also another advantage of DSL technology is the penggunaan of existing copper wires where the network had already reached the offices and homes so that the necessary infrastructure development to be not too expensive. But the use of an existing cable it should pay attention to several things related to the data signal. Such as attenuation, crosstalk, and noise (noise). Attenuation is weakening the signal caused by the presence of an increasingly far distance that must be taken by a signal, and also because of the increasing frequency of the signal. Due to the distance and frequency of the farthest distance that still probably is about 5.5 km with a bandwidth of about 1 MHz. Crosstalk will be ditimbulkan by the pair telephone wire is used.

This disorder can occur due to signals with the same speed of each cable can influence each other, when these disorders are higher compared to the data signal then akan arise many errors that slow down the speed of the flow of data. To avoid the effects of crosstalk can be created for each cable in one direction, so that the signal on each of the wires do not influence each other.

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