Aang Yogya's Post : Internet today has become a technological and data communication network of the most popular on the planet. At five years ago, telnet traffic and the World Wide Web is the dominant types of traffic. However, the form of services offered by the Internet increasingly diverse. Internet users start using the applications "killers", such as video conferencing, telemedicine, distance learning, and other services who spent much bandwidth.
However, conventional modem technology today that have a maximum rate of 56 kbps of course can not accommodate these new services. Internet users want the data transfer capacity of a larger order to use Internet applications fairly. Therefore, current xDSL technology is a suitable alternative that best applied to accelerate the transfer of data at the subscriber access lines.
DSL (Digital Subcriber Lines)
Digital Subscriber Lines, as the actual transmission technology developed for ISDN (Integrated Services Digital Network), Basic Rate Access Channel. DSL name used to describe the transmission technology or the physical layer for ISDN Basic Rate Access Channel. Currently, DSL, or also known as xDSL is used as a common naming system for all types of DSL.
Full-duplex transmission on the 2 wire telephone network, using 3 different methods:
However, conventional modem technology today that have a maximum rate of 56 kbps of course can not accommodate these new services. Internet users want the data transfer capacity of a larger order to use Internet applications fairly. Therefore, current xDSL technology is a suitable alternative that best applied to accelerate the transfer of data at the subscriber access lines.
DSL (Digital Subcriber Lines)
Digital Subscriber Lines, as the actual transmission technology developed for ISDN (Integrated Services Digital Network), Basic Rate Access Channel. DSL name used to describe the transmission technology or the physical layer for ISDN Basic Rate Access Channel. Currently, DSL, or also known as xDSL is used as a common naming system for all types of DSL.
Full-duplex transmission on the 2 wire telephone network, using 3 different methods:
- Frequency Division Multiplex (FDM)
- Time Compression Multiplex (TCM)
- Echo cancellation (EC)
Differences of opinion between TCM and the EC method for transmitting DSL still going on until today. The main issue is about the comparison of transmission losses, echo level, compatibility with other systems, and complexity of the system. Broadly speaking, the advantage of TCM systems do not require echo canceller, in separating the different directions of transmission that occurred at a time. But with the development of technology Very Large Integrated Circuits (VLSI), the echo canceller to realize to be more economical. EC system is potentially more complex, using 50% less transmission bandwidth than its competitors.
HDSL (High Data-Rate Digital Lines Subcriber)
HDSL is a better system to deliver T1/E1 through twisted-pair wire channels. HDSL requires smaller bandwidth and requires no repeaters. With the adoption of better modulation techniques, HDSL can transmit data with a transfer rate of 1.544 Mbps or 2.048 Mbps bandwidth only by about 80 kHz to 240 kHz or less when compared with that required by AMI. HDSL can deliver data at speeds above the channel along the 12 Kft 24 AWG, commonly called a CSA (Carrier Serving Area), and requires 2 pairs of wire channels for T1 and E1 3 pairs of channels for each working on or the total speed.
SDSL (Single-Line Digital Subcriber Lines)
SDSL is another type of HDSL. SDSL requires only a pair of wire-line course to deliver POTS and T1/E1. The major advantage compared with HDSL SDSL is easily applied in every customer because it only requires a regular phone lines. The drawback is only be used on the channel along the 10 Kft.
ADSL (Asymmetric Digital Subcriber Lines)
ADSL is the next development of HDSL. As the name implies, ADSL transmits data asymmetrically, ie different transmission capacity between now and the downstream (from network to customer) and at the upstream (from customer to network). Higher downstream capacity than upstream capacity. There are several reasons for the asymmetric data transmission, such as transmission capacity needs, the nature of the transmission line, and the application. Capacity needs that are not necessarily the same can be seen from custom yagn around today, that is usually the customer (eg Internet service subscribers) only requires the data retrieval (downloading) of information providers. If the information extracted in the form of multimedia information (or anything that has a relatively large data size), should be required transport channels with a large capacity for these downloads. On the other hand, customers rarely perform data transmission to the network (upload). If carried out, usually only in the form of control data to the provider of service or request information. Control data are nothing more than a series of characters that is relatively short. Therefore, only the required transmission channel with limited capacity yagn. There are times when customers upload to the network by sending data that is big enough. However, even this relatively less frequently performed than the download. From the above explanation, it can be concluded that the need to download much larger than uploading purposes. If forced to have the same rate, it will make the bandwidth becomes less efficient. If viewed from the transmission medium, the channels of the existing transmission (telephone lines) are not distributed one by one to each customer (single channel), but several channels into one channel in a single bundle. Usually there are 50 bundles in a single channel. With these conditions, interference antarsaluran will very likely happen a lot. Even if the bundle was the same one for data transmission in the opposite direction, the signal emitted on one side (the side of the cable bundle), which has a higher signal level that is still going to interfere with the recipient on the same side (same side of the cable bundle with a transmitter) with the signal level at receiver so weak. This event is called NEXT. However, if on the same bundle that is going on signal transmission in the same direction and the signal level that existed at the two lines can be regarded as strong, channel interference may also occur. Interference effect was smaller than NEXT. This event is called FEXT. In addition, if on the same channel to be full-duplex communication, communication is usually done by sending two signals (signals transmitted and received) with memodulasikannya on the same carrier frequency so that it will happen yagn called echo (the signal being emitted into the receiver signal return or signal return). Echo can usually be removed with the circuit echo canceller yagn not simple. From the application side, an adult is only required applications that can provide information in one direction, such as video-on-demand, home shopping, Internet access, remote LAN access, and multimedia access. Therefore, from all the explanation above, seems to be easier to build an ADSL system.
VDSL (Very High Data Rate Digital Subscriber Line)
VDSL previously referred to as VADSL because initially, VDSL can only transmit digital data, such as ADSL are asymmetric, but with higher capacity than ADSL and channel length is shorter. There is no general standard for VDSL. From some discussion that exists, a common downstream capacity for VDSL is 12.96 Mbps (STS-1; 4.5 Kft), 25.82 Mbps (STS-1; 4 Kft), and 51.84 Mbps (STS-1 ; 1 Kft). For the purposes of upstream capacity available between 1.6 Mbps to 2.3 Mbps. VADSL much contested term, especially by T1E1.4, because it shows something that is not always symmetric. In fact, many who want to one day be truly symmetric. Therefore, a preferred VDSL. In some ways, simpler than ADSL VDSL. Shorter transmission line on VDSL causes constraints on the channel that might occur on a longer channel can be suppressed. Therefore, its transceiver technology may become more simple and its capacity will be 10 times higher. VDSL is a target of ATM network architecture. VDSL allows passive network termination and can be used on more than one VDSL modems for use on customer channels, as well as regular analog phone systems (POTS)
Aang Yogya
HDSL (High Data-Rate Digital Lines Subcriber)
HDSL is a better system to deliver T1/E1 through twisted-pair wire channels. HDSL requires smaller bandwidth and requires no repeaters. With the adoption of better modulation techniques, HDSL can transmit data with a transfer rate of 1.544 Mbps or 2.048 Mbps bandwidth only by about 80 kHz to 240 kHz or less when compared with that required by AMI. HDSL can deliver data at speeds above the channel along the 12 Kft 24 AWG, commonly called a CSA (Carrier Serving Area), and requires 2 pairs of wire channels for T1 and E1 3 pairs of channels for each working on or the total speed.
SDSL (Single-Line Digital Subcriber Lines)
SDSL is another type of HDSL. SDSL requires only a pair of wire-line course to deliver POTS and T1/E1. The major advantage compared with HDSL SDSL is easily applied in every customer because it only requires a regular phone lines. The drawback is only be used on the channel along the 10 Kft.
ADSL (Asymmetric Digital Subcriber Lines)
ADSL is the next development of HDSL. As the name implies, ADSL transmits data asymmetrically, ie different transmission capacity between now and the downstream (from network to customer) and at the upstream (from customer to network). Higher downstream capacity than upstream capacity. There are several reasons for the asymmetric data transmission, such as transmission capacity needs, the nature of the transmission line, and the application. Capacity needs that are not necessarily the same can be seen from custom yagn around today, that is usually the customer (eg Internet service subscribers) only requires the data retrieval (downloading) of information providers. If the information extracted in the form of multimedia information (or anything that has a relatively large data size), should be required transport channels with a large capacity for these downloads. On the other hand, customers rarely perform data transmission to the network (upload). If carried out, usually only in the form of control data to the provider of service or request information. Control data are nothing more than a series of characters that is relatively short. Therefore, only the required transmission channel with limited capacity yagn. There are times when customers upload to the network by sending data that is big enough. However, even this relatively less frequently performed than the download. From the above explanation, it can be concluded that the need to download much larger than uploading purposes. If forced to have the same rate, it will make the bandwidth becomes less efficient. If viewed from the transmission medium, the channels of the existing transmission (telephone lines) are not distributed one by one to each customer (single channel), but several channels into one channel in a single bundle. Usually there are 50 bundles in a single channel. With these conditions, interference antarsaluran will very likely happen a lot. Even if the bundle was the same one for data transmission in the opposite direction, the signal emitted on one side (the side of the cable bundle), which has a higher signal level that is still going to interfere with the recipient on the same side (same side of the cable bundle with a transmitter) with the signal level at receiver so weak. This event is called NEXT. However, if on the same bundle that is going on signal transmission in the same direction and the signal level that existed at the two lines can be regarded as strong, channel interference may also occur. Interference effect was smaller than NEXT. This event is called FEXT. In addition, if on the same channel to be full-duplex communication, communication is usually done by sending two signals (signals transmitted and received) with memodulasikannya on the same carrier frequency so that it will happen yagn called echo (the signal being emitted into the receiver signal return or signal return). Echo can usually be removed with the circuit echo canceller yagn not simple. From the application side, an adult is only required applications that can provide information in one direction, such as video-on-demand, home shopping, Internet access, remote LAN access, and multimedia access. Therefore, from all the explanation above, seems to be easier to build an ADSL system.
VDSL (Very High Data Rate Digital Subscriber Line)
VDSL previously referred to as VADSL because initially, VDSL can only transmit digital data, such as ADSL are asymmetric, but with higher capacity than ADSL and channel length is shorter. There is no general standard for VDSL. From some discussion that exists, a common downstream capacity for VDSL is 12.96 Mbps (STS-1; 4.5 Kft), 25.82 Mbps (STS-1; 4 Kft), and 51.84 Mbps (STS-1 ; 1 Kft). For the purposes of upstream capacity available between 1.6 Mbps to 2.3 Mbps. VADSL much contested term, especially by T1E1.4, because it shows something that is not always symmetric. In fact, many who want to one day be truly symmetric. Therefore, a preferred VDSL. In some ways, simpler than ADSL VDSL. Shorter transmission line on VDSL causes constraints on the channel that might occur on a longer channel can be suppressed. Therefore, its transceiver technology may become more simple and its capacity will be 10 times higher. VDSL is a target of ATM network architecture. VDSL allows passive network termination and can be used on more than one VDSL modems for use on customer channels, as well as regular analog phone systems (POTS)
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