中英对照 xDSL技术.doc

XDSL TechnologiesXDSL TechnologiesXDSL conceptXDSL x means any character or string to adopt different modulation, a signal transfer speed and distance, and the different channels and downstream the channels symmetry.XDSL is a new form of transport technology, the existing copper phone lines, the higher frequency modulation, and related technology, the circuit or into a digital data signal processing technology to obtain higher transmission speeds (52mbps) up DSL technologies all the difference between the signal transmission speed and distance and the channels and downstream the channels symmetry in two ways different.ADSL2 and ADSL2+ADSL 2 the main technical features required(1) Rate of the wider adsl2 rate. In the area has more than the first generation of ADSL superior performance. The highest rate is downstream adsl2 12 MBITS, the highest rate of 1 MBITS.(2) The diagnosis. In order to the diagnosis and failure, the transport adsl2 the line ends of the measuring the noise attenuation and SNR (ring her letter than), these measures can be done by a special kind of diagnostic test module to gather data.(3) Of power. The first generation of ADSL technology transfer in no transfer data or all energy on work. If the modem ADSL can work in the standby sleep, and for millions of the modems are concerned, we can save a considerable amount of electricity. In order to achieve this end, adsl2 indicated two alternative power supply management pattern and by l2 and backward l3, this mode, ADSL keep in line, reduced total energy consumption the equipment.(4) Rate adaptive technology. By introducing adsl2 SNR (seamless rate) adaptation technology to solve these problems, makes adsl2 system can at work in no service was disrupted and wrong cases to change the linked rate.(5) More lines on the bound. Operators are required for different user has provided different services grade. (6) Channel for technology. ADSL2 can be divided into the different links of channels, which offer service for various applications.(7) Of improving interoperability, simplifies the initializing state machine and connection to chip in a different supplier of ADSLl transceiver, you can exchange operations and improving performance; a fast start: ADSL2 provides a fast start and from the time of adsls reduced to three tens, digital pattern: adsl2 provide an alternative mode, which made ADSL2 able to use a band for data transmission, you can increase 256 KITS data rate. Supports packet of service: adsl2 provide a package of transport modes of transport together, based on the package can be used to transport services.Adsl2 the technical characteristicsADSL2 in addition to their ADSL2 technical features, there is an important characteristic is expanded in the downstream adsl2 band, which increases within a short line at the downstream. ADSL2 two standards of the specified 1.1 MHZ and 552 KHZ downstream band, and 2.2 MHZ adsl2 appointed a band of downstream. This made in the short adsl2 (1.5 km) in the downstream rate has a very big increase its more than 20 MBIT. And adsl2 the rate of about 1 MBITS, it depends on the condition of the line. Use adsl2 can effectively reduce words. when adsl2 interference with ADSL1, on the line between the words, you can go down to work in the band settings between 1.1 2.2 MHZ to avoid downstream of ADSLl 1.1 MHZ band that produces nothing, to reduce the string and improve the quality of service.VDSL technologyVDSL (very - high - speed digital subscriber) line and high speed wire) digital subscriber is the bandwidth of transfers of the VDSL technologies, as is access to domestic users to take the final copper cable. VDSL technology has the following characteristics:(1)A transfer rate is high, to provide the right balance and asymmetric two types of transport modes. The asymmetry mode, can you attain the highest rate VDSL downstream 52 MBITS in the highest rate of symmetry can be reached 34 MBITS. VDSL overcome ADSL in the direction of the bandwidth of defects.(2) Transmission distance and limited. The transport distance of the inverse relationship is VDSL technologies. VDSL are universal by the channel to 12 MHZ for the transmission rate. the high frequency signals in the local call on the decline of attenuation, so the transport distance is very limited, and as their rate of increase will also be significantly reduced, the present general line transceiver VDSL can support the far more than 1.5 km of signal transmission.(3) To better support for various applications. VDSL is a transmission medium based on the physical layer VDSL standardized technology, but from the beginning of the work of the protocol stack frame map, and made detailed regulations, based on , ATM and PTM (via a packet mode, INTERNET and IP applications) various streams of data applications VHDL laid the foundation and avoid a standardized ADSL for the delay caused by the chief support of the INTERNET and IP applications, but needs and IP and ATM requires application but bind the embarrassing situation. (4) With higher spectral compatibility.HDLS technologyHDSL（High-speed Digital Subscriber Line）English, Chinese is called a high rate of televisions digital subscriber of ADLS, classical symmetry products, its ascending and downstream data bandwidth. The codes and standards in isdn, you can switch on the telephone and isdn connection. HDLS is the double line with multiple concurrent transport, is about 1. BPS 5m 2m data stream to separate two or three of the double line of each line, the messaging rate and increase the transport distance. In each of the line for the realization of full duplex offset by technology transfer. With HDSL in two or three for two for the transfer rates and t1 line or e1 transfer rates are identical, therefore generally used as a relay t1 e1 alternative solutions. HDSL to implement than simple, costs and lower, adsls about 1 5.HDSL is the XDSL in the development of early, the application of more widely used to hold back the wave, and high-speed digital processing technology based, use, using two 2b1q to double the line of symmetry to two-way data transmission, transfer rate 2048kbps 1544kbps lines, the transmission rate for 1168kbits, the use of wire gauge 24awg（American of American cable ） of the line is 3 （ 51mm ） the transport distance can be reached 3. 4KM, Provides t1 standard e1 and v. 35 Interface.SDLS technologySDLS is called symmetrical number of users with access to the line is the transmission technology, it is of HDLS version is also called data user SDLS and downstream to the transmission rate of the same digital subscriber line. He only needed a pair of copper DSL,SDSL （ symmetric DSL symmetry DSL ） HDSL is a kind of change form, it only use the cable is providing from 144 kb s to 1.5 s speed. HDSL is the rate of adaptive technology and HDLS, SDLS is not a single circuit the telephone.The technical characteristics of a ： and access to the routers with SDSL, as a client device ； Through the yards actuate the switches end for end the other end of the council as a client device, to some applications. pay attention to the game end and the client access - SDLS modem device speed settings must be unanimous, or no communication ； for DLS, data transfer rates can, through the yards and set up your rate for 256kb s 2304kb s adjust paces 128kb s ；DLS line interfacing 2b1q code using encoded ； 10base - t interface ： in three standard ； ieee802. the transport distance ：2304K：3.5km (0.5mm):256K: 7km (0.5mm).RADSL technologyThe shih: SDSL RADSL is the work at the beginning of the modem line first test, the rate of work to line can cope with the highest speed. RADSL（ adaptive DSL rate, the rate of adaptive DSL ） is a signal quality is based on the speed of ADSL version of ADSL technology. Many are in fact RADSL.Users and technical characteristicsRADSL （ rate - ADAPTIVEDSL, the rate of digital circuit ） to the user is on the basis of ADSL develop new generation of access technique that allows the service providers adjustment of the XDSL connection with the actual needs and solve the problem, and to remote users reliable data network access. It is the use of twin ： the transmission line ； support synchronous and not a transport mode ； rate, the rate to go down from 1 to 8mbps 5mbps, the rate from 16kbps 640kbps ；To support the data and voice, it is particularly applicable to rain, the high temperature of the environment.xDSL技术1. xDSL概念xDSL中“x”表示任意字符或字符串，根据采取不同的调制方式，获得的信号传输速率和距离不同以及上行信道和下行信道的对称性不同。 xDSL是一种新的传输技术，在现有的铜质电话线路上采用较高的频率及相应调制技术，即利用在模拟线路中加入或获取更多的数字数据的信号处理技术来获得高传输速率(理论值可达到52Mbps)。各种DSL技术最大的区别体现在信号传输速率和距离的不同，以及上行信道和下行信道的对称性不同两个方面。2. ADSL2与ADSL2+2.1 ADSL2的主要技术特性 (1)速率提高、覆盖范围扩大。ADSL2在速率、覆盖范围上拥有比第一代ADSL更优的性能。ADSL2下行最高速率可达12 Mbit/s，上行最高速率可达1 Mbit/s。 (2)线路诊断技术。 为了能够诊断和定位故障，ADSL2传送器在线路的两端提供了测量线路噪声、环路衰减和SNR(信噪比)的手段，这些测量手段可以通过一种特殊的诊断测试模块来完成数据的采集。(3)增强的电源管理技术。第一代ADSL传送器在没有数据传送时也处于全能量工作模式。如果ADSL Modem能工作于待机/睡眠状态，那么对于数百万台的Modem而言，就能节省很可观的电量。为了达到上述目的，ADSL2提出了两种电源管理模式，低能模式L2和低能模式L3，这样，在保持ADSL“一直在线”的同时，能减少设备总的能量消耗。 (4)速率自适应技术 。ADSL2通过采用SRA(Seamless Rate Adaptation)技术来解决这些问题，使ADSL2系统可以在工作时在没有任何服务中断和比特错误的情况下改变连接的速率。(5)多线对捆绑技术 。运营商通常需要为不同的用户提供不同的服务等级。 (6)信道化技术 。ADSL2可以将带宽划分到具有不同链路特性的信道中，从而为不同的应用提供服务。 (7)其它优点 。改进的互操作性:简化了初始化的状态机，在连接不同芯片供应商提供的ADSL收发器时，可以互操作并且提高了性能; 快速启动:ADSL2提供了快速启动模式，初始化时间从ADSL的10 s减少到3 s; 全数字化模式:ADSL2提供一个可选模式，它使得ADSL2能够利用语音频段进行数据传输，可以增加256 kbit/s的数据速率。支持基于包的服务:ADSL2提供一个包传输模式的传输汇聚层，可以用来传输基于包的服务。 2. 2 ADSL2+的技术特点 ADSL2+除了具备ADSL2的技术特点外，还有一个重要的特点是扩展了ADSL2的下行频段，从而提高了短距离内线路上的下行速率。ADSL2的两个标准中各指定了1.1 MHz和552 kHz下行频段，而ADSL2+指定了一个2.2 MHz的下行频段。这使得ADSL2+在短距离(1.5 km内)的下行速率有非常大的提高，可以达到20 Mbit/s以上。而ADSL2+的上行速率大约是1 Mbit/s，这要取决于线路的状况。使用ADSL2+可以有效地减少串话干扰。当ADSL2+与ADSL混用时，为避免线对间的串话干扰，可以将其下行工作频段设置在1.1 2.2 MHz之间，避免与ADSL的1.1 MHz下行频段产生干扰，从而达到降低串扰、提高服务质量的目的。 3.VDSL技术VDSL(Very-high-speed Digital Subscriber Line)，甚高速数字用户线)是目前传输带宽最高的一种xDSL接入技术，被看作是向住宅用户传送高端宽带业务的最终铜缆技术。VDSL技术具有下列特点: (1)传输速率高，提供上下行对称和不对称两种传输模式。在不对称模式下，VDSL最高下行速率能够达到52 Mbit/s，在对称模式下最高速率可以达到34 Mbit/s。VDSL克服了ADSL在上行方向提供的带宽不足的缺陷。 (2)传输距离受限。带宽和传输距离呈反比关系是DSL技术的普遍规律，VDSL是利用高至12 MHz的信道频带来换取高的传输速率的。由于高频信号在市话线上的大幅衰减，因此其传输距离是非常有限的，而且随着距离的增加其速率也将大幅降低，目前VDSL线路收发器一般能支持最远不超过1.5 km的信号传输。 (3)能较好地支持各种应用。VDSL是一个基于传输媒介的物理层技术，但VDSL从标准化工作一开始，就在协议栈、帧映射等方面进行了详细的规定，从而为基于STM、ATM和PTM(Packet Transfer Mode，即Ethernet和IP应用)各种数据流的VDSL应用奠定了基础，避免了ADSL因标准化的相对滞后而导致的目前主要支持Ethernet和IP应用但却需要和ATM绑定的尴尬局面。 (4)具有较好的频谱兼容性。 4.HDSL技术HDSL（High-speed Digital Subscriber Line）的英文简称,中文称为高速率数字用户线路是ADSL的对称式产品,其上行和下行数据带宽相同。它的编码技术和ISDN标准兼容 ,在电话局侧可以和ISDN交换机连接。HDSL采用多对双绞线进行并行传输,即将1.5M/2M bps的数据流分开在两对或三对双绞线上传输,减低每线对上的传信率,增