xDSL: CHAPTER 16

Internet accesses before using ILEC or Incumbent Local Exchange Carriers has many problems including the ability of maintaining and preserving their installed base. ILEC want to have high speed communication ability and more correct internet access. That’s why they continue to find way to have a new technology that can solve their problem. ILEC have an installed base of unshielded twisted pair in the local loop, and because of this they invented a new technology called xDSL in order to exist the copper cable plant. DSL is known as digital subscriber line, the lower X stands for many variations. Those variations including the following, Asymmetrical DSL, ISDN or ISDL, High-bit rate DSL, Consumer DSL, Single High speed DSL, Rate-adaptive DSL, Very high- bit rate DSL, single DSL. But the most popular on variation is the Asymmetrical DSL because it supports the cable plant and it has a speed that varies depending on the quality of copper.

ADSL produced a high speed transmission using the twisted pair telephone lines and under the current technology it uses the speed between 1.5 to 6 Mbps. They said that in the future the ADSL will carry the speed of 8.192 Mbps and it is very possible to happen. The services that DSL provides are voice, multimedia, data, video, and internet streaming protocol service.

 ISDL or ISDN_DSL is a technique that uses digital and operating at two channels of 64 Kbps for voice or non voice and 16 Kbps for data channel for signaling, control and data packets. ISDN couldn’t catch faster but it is demandable because the carriers caught off- guard when users demand was moderate, escalated so quickly. 

HDSL is developed as more efficient way of transmitting; it does not require the repeater on a local loop above 12K. HSDL is more efficient because the bridge taps will not bother the service and the splices are left in place. It can deliver 1.544 Mbps.

SDSL provides a high speed communications using a single cable pair and a distance of not greater than 10K. Despite of this distance, SDSL can deliver a 1.544 Mbps on a single cable pair. Still it has an advantage to produce a god communication. The limitation of the distance of SDSL is now supported by the use of ADSL. Now the distance becomes 18K by the help of ADSL.

RADSL is made to develop the variations and speed of transmission. IT gives the flexibility to adopt the changing in each direction during the transmission. It can also provides 768 Kbps, that’s why ILEC used this.

CDSL provide only 1 Mbps in download direction and 160 Kbps for upward direction. But still the consumers want to use this because it does not need any splitter on the line.

SHDSL supports the repeaters which further increase the reach capability of some technologies. One of the advantage of SHDSL is that is has an increasing symmetrical bandwidth during installation. SHDL provides the services to the remote LAN access, Web-hosting, application sharing, and video conferencing.

VDSL is faster and more reliable to used, obviously we know that it is fast because the name of very high bit rate. It uses a fiber feed to deliver VDSL so that they can achieve the speed that they want.

Now we know how important those variation in providing the DSL to reach their goal and to satisfy the ILECs for the improvement of their technological device so it can carry the needs of the consumers or the end users. Fast and safe communication is the most important thing that the users needed, the secondary is the cost. That’s why this xDSL made in order to give what they want.

Reference: Broadband Telecommunication Handbook: 2^nd edition by Regis Bates