(This is what I found on the Internet when I was studying, I hope it can help you
Kirin: Please write a brief introduction to the contents of the attachment, so that the readers can read it. Thank you, please check the top page for details.
An introduction to the contents of the attachment, with attached drawings.
Network integrated wiring model description and diagram/xdsl/index.htm#1] 1. Overview
Network integrated wiring model description and diagram/xdsl/index.htm#2] Second, the realization
Network integrated wiring model description and diagram/xdsl/index.htm#3] 3. Principle
Network integrated wiring model description and diagram/xdsl/index.htm#4] 4. Classification
Network integrated wiring model description and diagram/xdsl/index.htm#5] 5. Scope of use
I. Overview
Current copper telephone lines carry voice traffic at 28.8Kbps (56Kbps with the help of software). These lines use the existing telephone network and do not require any additional hardware or software. The advantage is that any Where the telephone network is reachable, but this is also where it fails: the entire network is wired at the rate requirements of the past.
In an ideal environment, the speed of the copper wire is only limited by the attenuation of the cable, but in the existing telephone network, the bandwidth is greatly restricted by the filter and the network itself. Upgrading the existing copper twisted pair can greatly improve the overall network performance, but it is expensive, so there is a need for a method that can not only use the existing cable but also significantly improve the performance. Bellcore built the first generation of digital subscriber technology and coined the term DSL. The aim is high performance, low cost: at least 2Mbps bandwidth over existing copper wire networks. DSL uses a combination of software and electronic technology to make up for some of the shortcomings of copper wire.
DSL gives everyone:
.Almost immediate network upgrade
. Cheaper option than fiber and coax
.more reliable data transmission
xDSL is the collective name of DSL (Digital Subscriber Line), which means digital subscriber line, which is a point-to-point transmission technology using copper telephone lines as the transmission medium. DSL technology supports symmetric and asymmetric transmission modes on the subscriber loop of the traditional telephone network (POTS), solving the transmission bottleneck problem that often occurs in the last mile between the network service provider and the end user. Since a large number of telephone user loops have been laid, how to make full use of the existing copper cable resources and achieve high-speed access through copper twisted pairs has become the focus of the industry's research. Therefore, DSL technology has quickly received attention, and has been widely used in some countries. and regions are heavily used. 2. Realization
The xDSL system is mainly composed of central office equipment (DSLAM--DigitalSubscriberLineAccessMultiplexer) and customer end equipment (CPE). The realization principle is shown in the following figure.
file:///Z:/TEMP/Rar$EX03.656/zonghebuxian/Network integrated wiring model description and diagram/xdsl/xdsl1.jpg
The central office consists of a DSLAM access platform, a DSL central office card, a voice splitter, and an IPC (data convergence device), among which IPC is an optional device. The voice splitter separates the audio signal and the high-frequency digital modulation signal on the line, and sends the audio signal to the telephone exchange, and the high-frequency digital modulation signal is sent to the DSL access system; the DSLAM access platform can simultaneously insert different DSL access The central office card modulates the signal on the line into a digital signal and provides a data transmission interface; IPC provides different WAN interfaces for the DSL access system, such as ATM, frame relay, T1/E1, etc. These devices are located in the switch room of the telephone system.
User equipment consists of DSLModem and voice splitter. DSLModem modulates and demodulates user's data packets and provides data transmission interface. 3. Principle
1. Other transmission technologies
The traditional telephone system uses the frequency of 0 to 3KHz to transmit voice on the user loop. The telephone switch converts the analog voice signal into a 64Kbps (zero-order) digital signal, and combines multiple voice signals into T1/ E1 or higher, transmitted to other switches via fiber or copper cables. Therefore, due to the limitations of the telephone system, the digital transmission rate using the telephone connection is not very high (33.6/56Kbps).
The ISDN basic rate integrated digital service network can provide users with a transmission rate of 2B D=160Kbps, and users can utilize this bandwidth separately or in combination using digital terminals. ISDN utilizes the 80-100KHz frequency of the line to transmit signals.
Through the T1/E1 baseband dedicated line technology of the user loop, the traditional T1/E1 dedicated line technology uses a very simple baseband modulation method AMI (T1) or HDB3 (E1) to transmit signals. Due to the limitation of modulation technology, the transmission distance is very short, which requires Install an amplifier in the line, the signal efficiency is high, and the interference is large. 2.DSL technology
DSL technology uses high frequency signals that are not utilized in telephone systems to transmit data. DSL utilizes more advanced modulation techniques:
2B1Q--Baseband modulation technology developed from AMI technology, which can use half of the frequency band of AMI to achieve the same transmission rate as AMI. It is mainly used in H/SDSL technology because it reduces the frequency band requirement and increases the transmission distance.
·QAM--the technology used by traditional dial-up Modem, MVL expands it to high frequency band, and integrates multiplexing technology to support multiple Modem sharing the same line.
CAP--The carrier frequency is variable, and it transmits 2 to 9 bits of binary data in one frequency cycle or baud, so under the same transmission rate, it occupies less bandwidth and transmits farther, mainly used in H/SDSL , RADSL.
·DMT--The high frequency band is divided into multiple frequency windows, and each frequency window modulates one channel separately. Due to the interference between the frequency bands, the transmission distance is relatively short, and it is used in ADSL. DMT has become the modulation standard-T1.413 used by ADSL formulated by ANSI.
The table below compares the use of various encoding techniques in different DSL technologies.
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This post was last edited by kirin at 2008-6-1614:07]
This document includes the following attachments:
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