Category: dsl

DSL – System Components In this chapter, we will discuss the Transport System, Local Access Network, Multiservice DSLAM, DSL Modem/Router and several other DSL System Components. Transport System This component provides the carrier backbone transmission interface for the DSLAM System. This device can provide service specific interfaces such as − T1/E1 T3/E3 OC-1 OC-3 OC-12 STS-1 and STS-3. Local Access Network The local access network uses inter-CO local carrier network as a foundation. To provide connectivity between multiple service providers and users of multiple services, additional hardware may be required. Frame Relay switches, ATM switches and / or routers may be provisioned in the access network for this purpose. Increasingly, ILECs and PTO are looking for ATM equipment to fulfill this role, and next-generation DSLAM include ATM Switching to accomplish it. Sometimes, it is instructive to consider the concept of an Access Node (AN), which is where the switches and / or routing equipment are physically located. Depending on the scale of the desired access network and the costs associated with transportation, we can expect to find one or more AN by local access network, creating an overlay structure on top of the inter-CO network. In some cases, the AN is integrated in the DSLAM, as is the case with the new generation of DSLAM that incorporate ATM switching systems. Multiservice DSLAM Residing in the CO environment (or in a space of near virtual collocation), the DSLAM is the cornerstone of DSL solution. Functionally, the DSLAM concentrates the data traffic from multiple DSL loops on the base network for connection to the rest of the network. The DSLAM provides Backhaul Services for the packet, cell and / or circuit-based applications through concentration DSL ON 10Base-T lines, 100Base-T, T1 / E1, T3 / E3 ATM or outputs. Some DSLAMs are maintaining the temperature “hardened” for installation in areas that are not controlled environment. This allows the installation of the Remote Terminals in DSLAM or sidewalk cabinets instead of just in the central or virtual collocation spaces. The ability to move the DSLAM in these remote locations (with extended range loop technologies) can significantly increase the footprint of a service provider, for the provision of services to customers that would otherwise be out of reach of DSL In addition to concentration and functions according to the specific service being provisioned, a DSLAM provides added features. The DSLAM may, in some cases be necessary to open the data packets to take action. For example, to support the dynamic IP address assignment using the Dynamic Host Control Protocol (DHCP), each packet must be considered in order to direct packets to the right destination (that is considered as a function DHCP-relay). DSL Modem/Router The criterion for assessment modem / DSL Router is the customer site equipment to connect the service user to DSL loop. The end point of DSL is generally 10/100Base-T, V.35, ATM or T1 / E1, along with the new generations of consumer products, which also support methods such as USB, IEEE 1394 (Firewire) and factor internal PCI form. In addition, CPE parameters are being developed with additional ports designed to support specific applications, such as RJ11 ports for support of voice (for e.g. IADs for service VoDSL), ports Video for video services based on DSL, and new networking interfaces such as Home Phoneline Networking Alliance (HomePNA) or wireless network such as 802.11 wireless Ethernet interfaces. The DSL CPE devices are available in a number of different configurations depending on the specific service being provisioned. In addition to providing basic DSL modem functionality, many parameters have additional features such as bridging, routing, ATM multiplexing or TDM. The Bridged Parameters serve the market well with ease of installation and maintenance. All work bridge setting device should have a learning filter to keep unwanted traffic crossing the network. Routed IP settings provide flexibility to the customer”s site. With a point of IP-termination current, subnets can be created and maintained for effective segmentation of remote LAN and multicast and unicast downstream recognition. Multiple service areas may also be used by remote users on the LAN at the same time. Several service areas become important when you have a large group of users who need access to various service providers such as the corporate LAN and the Internet through different ISPs. The transparent protocol parameters behave like a DSU / CSU. They provide an interface for DSL link for routers and / or existing FRAD, which are Frame Relay Access Devices. Routers and FRAD manage the overall management of network traffic is plugged in, while the final point of DSL pass all traffic to the upstream DSL link. The Channelized TDM parameters can function as DSU / CSU for T1 traditional service / E1. They also provide router interfaces, FRAD, multiplexers, PBX or any other device used to a traditional service. The DSL modem / router must be designed, so that it can be installed with little or no required configuration. In addition, many service providers have demanded that the end of the DSL to be installed by the service user, requiring simply plug and play. DSL endpoint must be very manageable by the service provider. Generally, the features search for the following points − Ability to provide Layer 1 and 2 management statistics such as signal-to noise ratio. Ability to provide Layer 3 MIB statistics such as packet counts. Devices that are fully manageable by the service provider, without the need for on-site personnel. Devices that support performance monitoring and end-to-end visibility for rapid fault detection, isolation and correction. Ability to be remotely downloaded with new software as required. Interoperability with third-party CPE including IAD. POTS Splitters and Microfilters The POTS splitters option lie in both the CO and service users slots, allowing copper loop to use for media transmission, simultaneous DSL high-speed data and the single line telephone service, when the DSL variant uses these services. POTS splitters generally come in two configurations − A single separator version designed for mounting to the residence

DSL – Basics A wide range of DSL technologies and DSL products have entered the market, bringing with them both the opportunity and confusion. This chapter provides an overview of the technology, which can transmit information via copper lines and changing various DSL technologies. After understanding this concept, you can be better prepared to assess DSL technology and related products. Basic DSL Concepts The PSTN and supporting local access networks have been designed with guidelines that transmissions are limited to an analog voice channel 3400 Hz. For example − Telephones, Modems, Dial Fax Modem and Private Line Modems have limited their transmissions on local access telephone lines to the frequency spectrum between 0 Hz and 3400 Hz. The highest information rate possible using 3400 Hz frequency spectrum are less than 56 Kbps. So how does DSL achieve information rate in the millions of bits per second on the same copper lines? The answer is simple − Eliminate the limit of 3400 Hz frequency boundary, much like the traditional T1 or E1, which uses a much wider range of frequencies than the voice channel. Such an implementation requires the transmission of information over a wide frequency range of one of the ends of the copper wire loop to another accessory, which receives the frequency width of the signal at the end of the copper loop. As we have now understood that we can choose to remove the limit frequency 3400 Hz, and increase the supported information rate on copper son; you may be wondering, “Why not we just ignore POTS guidelines transmission and the use of higher frequencies?” Attenuation & Resulting Distance Limitations Let us understand regarding attenuation and the other factors that result in distance limitations. Attenuation − The dissipation of the power of a transmitted signal as it travels over the copper wire line. In-home wiring also contributes to attenuation. Bridged taps − These are unterminated extensions of the loop that cause additional loop loss with loss peaks surrounding the frequency of the quarter wavelength of the extension length. Crosstalk − The interference between two wires in the same bundle, caused by the electrical energy carried by each. One can compare the transmission of an electrical signal to drive a car. The faster you go, the more energy you burn over a given distance and the sooner you have to refuel. With electrical signals transmitted on a line of copper wire, the use of higher frequencies to support high-speed services also leads to shorter loop scope. This is because the high frequency signals transmitted by wire loops attenuate energy more quickly than low frequency signals. One way to minimize attenuation is to use lower resistance wire. Thick wires have less resistance than thin wires, meaning lesser signal attenuation and therefore, the signal can travel a longer distance. Of course, thick gauge wire means more copper, which results in higher costs. Hence, the phone companies have designed their cable plant by using the thinner gauge wire that could support the required services. Advanced Modulation Techniques Minimize Attenuation In the early 1980s, equipment providers actively worked to develop basic rate ISDN, which provided up to 64 Kbps two B channels plus one D channel 16 kbps used for signaling and packet data. The payload of the information, and other overhead costs associated with the implementation, led to 160 Kbps in total transmitted information. A key requirement of ISDN was that it had to reach customers on existing copper, equivalent to 18,000 feet. However, an AMI Implementation of basic rate ISDN would require the use of the lower part 160,000 Hz, resulting in too much attenuation of the signal and is below 18,000 feet, which is the necessary loop carried on the wire 26 gauge In 1988, advances in signal processing and coding line has doubled the efficiency of the AMI code inheritance by sending two bits of information in each cycle of analog waveform or transmission. The line of code was called 2 binary, 1 Quaternary (2B1Q). A 2B1Q implementation of ISDN basic rate uses frequencies ranging from 0 (zero) to about 80,000 Hz, which has less attenuation and results in the desired loop reach of 18,000 feet. History about ADSL Line Codes Around the same time (1980’s decade), the industry recognized asymmetric attributes of the local loop that telephone companies had developed a strong interest in providing video entertainment services. This interest has been motivated by the desire to increase revenue through new services and recognizing that non-US cable television operators have started offering voice services over their plant coaxial cable. By late 1992, three line codes were emerging as the most likely technologies to support high-speed video dial tone services. These were − QAM, or Quadrature Amplitude and Phase Modulation, a line coding technique used in modems for over 20 years. CAP, which was introduced earlier for HDSL and is actually a variant of QAM. DMT, or Discrete MultiTone, a line coding technique that was patented (but not implemented) by AT&T Bell Labs over 20 years ago. Unlike 2B1Q, which is a baseband technology that transmits at frequencies, which include 0 Hz or DC, the line codes mentioned above are typically bandwidth and may be designed to operate in any frequency range specified. DSL was originally designed as a residential service that needs to coexist independently with the POTS already provisioned. Therefore, the bandwidth attributes were considered a prerequisite for the frequency separation between FDM or POTS, a user upstream channel service on the network, and a downlink from the network to the user services. In addition to the implementation of FDM above, some DSL technologies, including some implementations of DMT, were designed to provide an echo canceller of the upstream and downstream channels to minimize the use of frequencies more high and optimize loop reach. However, some observers believe that the performance of these systems echo canceled, tend to deteriorate. A growing number of similar services are deployed in the same cable bundle, offsetting the substantial gains

DSL Tutorial Job Search Digital Subscriber Line (DSL) technology is a copper loop transmission technology, which satisfies bottleneck problems often associated with the last mile between the network and the service providers. This is an introductory tutorial, which covers the basics of the DSL Technology. Audience This tutorial is created for engineers who are new to the DSL Technology. This tutorial provides simple, easy to understand explanations with useful working examples. We will go through most of the modules of DSL, so the reader can also use this as a reference for their projects. Prerequisites There are no specific prerequisites for understanding this tutorial. It will be helpful for the readers, if they are from the telecommunications background. Additionally, it will be advantageous if the reader knows the various equipment used in DSL, its protocols and configurations and other related technologies. Learning working make money

DSL – Home DSL Home is an initiative taken by DSL-Forum. The following points will describe its various features and advantages. To define requirements related to home devices like residential gateways, VoIP devices and local & remote management of home devices. To enable triple/quad play services to the end-user(s) like voice, video, data, including IPTV, video on demand, content on demand, etc. DSL Home remote management protocol (TR-69) and its extensions are access agnostic. Remote Management is the core of DSL Home or next generation Residential Gateway (RG) & in-home networking. DSL Home group has come up with the standards for CPE requirements and management of the CPE devices. Standards defining requirements − WT-124 − Issue 2 of TR-068 − Residential Gateway defining complete RG requirements that not specific to DSL but includes other access technologies like xPON. TR-122 defines Voice ATA Requirements. Standards in management framework − TR-64 − LAN Side CPE Configuration and Enhancements. For configuration and management of CPE devices via local LAN interface. TR-69 − CPE Wan Management Protocol For configuration and management of the CPE device through remote side. TR-111 − allows TR69 remote management for the devices in the Home Network (HN). TR-98 and TR-133 − Configuration and Management of Service differentiation (QoS) parameters in the CPE devices through TR-69 and TR-64 respectively. TR-104 Data model for VoIP services Extended for Video services too. TR-106 defines the common data model template Defines the baseline object structure and a set of accessible parameters for a TR-69 device. TR-122 − defines Voice ATA Requirements. WT-135 − object model for the STB devices. WT-140 − object Model Network Storage Devices. WT-142 − Framework for TR-069 enabled PON devices. DSL Technology Options The following table describes the various DSL Technology options in detail. Family ITU Name Ratified Maximum Speed capabilities ADSL G.992.1 G.dmt 1999 7 Mbps down 800 kbps up ADSL2 G.992.3 G.dmt.bis 2002 8 Mb/s down 1 Mbps up ADSL2plus G.992.5 ADSL2plus 2003 24 Mbps down 1 Mbps up ADSL2-RE G.992.3 Reach Extended 2003 8 Mbps down 1 Mbps up SHDSL (updated 2003) G.991.2 G.SHDSL 2003 5.6 Mbps up/down VDSL G.993.1 Very-high-data-rate DSL 2004 55 Mbps down 15 Mbps up VDSL2 -12 MHz long reach G.993.2 Very-high-data-rate DSL 2 2005 55 Mbps down 30 Mbps up VDSL2 – 30 MHz Short reach G.993.2 Very-high-data-rate DSL 2 2005 100 Mbps up/down Convergence at Home Multiple broadband and networking technologies are converging in the next generation digital home, such as − ADSL2/ ADSL2 Plus / VDSL2 / xPON. Wireless/Ethernet/USB/HomePlug A/V, HPNA, etc. Consumer electronics begin to network. Management of such convergence is complex, driving the need for simplification of end device provisioning and maintenance Challenge − How to manage different elements within the home? Solution − Essentially home networking represents a microcosm of all networking technologies and techniques that Conexant makes. Convergence is happening first in the home. Today you need to be an IT expert (or have some teenagers in the house) to setup and configure your in-home networking devices. As addressed in the Industry, Applications and Technology Trends presentation, 30 − 50% of home networked devices are returned to the retailers with no trouble found. The users simply were unable to setup and configure the device using existing tools/software. Problems with the Existing Approach Following are the problems with the existing approach. User Perspective No flexibility to buy any equipment off-shelf. No support from the service provider, if the equipment is bought. Devices are not plug-n-play requiring both ISP & user to do some configuration. Adding a new service requires both ISP & end-user coordination, which takes time. Requires customer presence at home, if truck roll is involved. Could be difficult to match as more couples are working nowadays. Service Provider Perspective Requires Truck Roll to activate any new services, troubleshooting and new installations. Each truck roll adds to a significant cost in terms of time and resources. When customer lodges a complaint, then it is very difficult for the “Helpdesk” to verify what is wrong with the CPE device by sitting in their office. Vendors provide their own proprietary solution, different interfaces, parameters and procedures. Hence the need for training per vendor solution. ISP forced to stick with a few chosen vendors because ISP has done custom automation to make their job easier. Switching to a new vendor may require changing custom automation. No way to discover the device-capabilities automatically and determine what parameters are supported. Not possible to determine if user-changed configuration information via local management interface like Web, CLI, or SNMP, etc. Not possible to prevent users from changing settings, which may affect the services offered by them. Services Offered by DSL Home − TR-69 Following are the list of services Offered by DSL Home − TR-69. Remote management of the devices in a secure manner (uses SSL/TLS based security). Real-time provisioning of services via auto-configuration. Status and performance monitoring. Diagnostics Access Control Notification Firmware upgrade Standardized data model tailored specially for CPE devices offering various services like voice, video, data and IPTV, etc. Includes wide coverage for LAN devices in the home segments (STB, VoIP, NAS) on different LAN technologies like − Ethernet, USB, WLAN, etc. Management protocol is to access technologies agnostics, thus it could be used for wide variety of CPE devices. For example − xPON, xDSL, etc., just requires the device to be IP addressable. Truckroll is minimized by Remote management. The Helpdesk can provide better services instead of just taking the complaint. Helpdesk has more context and can see complete configuration information about CPE from remote. No need to have vendor-specific training as data model is standardized for services so less need of training the staff. No custom automation required hence offering wider vendor base to choose from Provides automatic discovery of parameters available on the device. Provides Access control, hence allows prevention from user changing the specific configuration. Provides Notification mechanism, thus we get to know any change in configuration related to the services. Reduces Opex. Making

DSL – Quick Guide DSL – Overview Digital Subscriber Line technology is a Copper Loop Transmission Technology, which satisfies bottleneck problems that are often associated with the last mile between the network and service providers. While DSL technology provides dramatic improvements in speed, (up to 8+ Mbps) compared to other network access methods, the true strength of DSL-based service opportunities lies in the actions like − Multimedia applications required by today”s network users. Performance and reliability. Economics. As shown in the following sample comparison chart, DSL-based services offer Performance Benefits for the Network Service Users when compared to other network access methods. In Addition, DSL-based services expand these operational improvements for public and private (Campus) operators. One of the compelling advantages of DSL technology is that it is the NSP and helps the Service Users to take full advantage of the existing infrastructure, layer two and layer three Protocols (such as Frame Relay, ATM and IP), and have reliable network services already entrusted to come. DSL can easily support advanced business-class services such as Voice over DSL (VoDSL) and new variants of proven and well-understood technologies such as the Frame Relay over DSL (FRoDSL). The latest generation of DSL equipment also offers end-to-end Service Level Management (SLM). For simplicity, in our discussion regarding business class DSL applications, we will group all of these under a new acronym − SLM-DSL. DSL – Basics A wide range of DSL technologies and DSL products have entered the market, bringing with them both the opportunity and confusion. This chapter provides an overview of the technology, which can transmit information via copper lines and changing various DSL technologies. After understanding this concept, you can be better prepared to assess DSL technology and related products. Basic DSL Concepts The PSTN and supporting local access networks have been designed with guidelines that transmissions are limited to an analog voice channel 3400 Hz. For example − Telephones, Modems, Dial Fax Modem and Private Line Modems have limited their transmissions on local access telephone lines to the frequency spectrum between 0 Hz and 3400 Hz. The highest information rate possible using 3400 Hz frequency spectrum are less than 56 Kbps. So how does DSL achieve information rate in the millions of bits per second on the same copper lines? The answer is simple − Eliminate the limit of 3400 Hz frequency boundary, much like the traditional T1 or E1, which uses a much wider range of frequencies than the voice channel. Such an implementation requires the transmission of information over a wide frequency range of one of the ends of the copper wire loop to another accessory, which receives the frequency width of the signal at the end of the copper loop. As we have now understood that we can choose to remove the limit frequency 3400 Hz, and increase the supported information rate on copper son; you may be wondering, “Why not we just ignore POTS guidelines transmission and the use of higher frequencies?” Attenuation & Resulting Distance Limitations Let us understand regarding attenuation and the other factors that result in distance limitations. Attenuation − The dissipation of the power of a transmitted signal as it travels over the copper wire line. In-home wiring also contributes to attenuation. Bridged taps − These are unterminated extensions of the loop that cause additional loop loss with loss peaks surrounding the frequency of the quarter wavelength of the extension length. Crosstalk − The interference between two wires in the same bundle, caused by the electrical energy carried by each. One can compare the transmission of an electrical signal to drive a car. The faster you go, the more energy you burn over a given distance and the sooner you have to refuel. With electrical signals transmitted on a line of copper wire, the use of higher frequencies to support high-speed services also leads to shorter loop scope. This is because the high frequency signals transmitted by wire loops attenuate energy more quickly than low frequency signals. One way to minimize attenuation is to use lower resistance wire. Thick wires have less resistance than thin wires, meaning lesser signal attenuation and therefore, the signal can travel a longer distance. Of course, thick gauge wire means more copper, which results in higher costs. Hence, the phone companies have designed their cable plant by using the thinner gauge wire that could support the required services. Advanced Modulation Techniques Minimize Attenuation In the early 1980s, equipment providers actively worked to develop basic rate ISDN, which provided up to 64 Kbps two B channels plus one D channel 16 kbps used for signaling and packet data. The payload of the information, and other overhead costs associated with the implementation, led to 160 Kbps in total transmitted information. A key requirement of ISDN was that it had to reach customers on existing copper, equivalent to 18,000 feet. However, an AMI Implementation of basic rate ISDN would require the use of the lower part 160,000 Hz, resulting in too much attenuation of the signal and is below 18,000 feet, which is the necessary loop carried on the wire 26 gauge In 1988, advances in signal processing and coding line has doubled the efficiency of the AMI code inheritance by sending two bits of information in each cycle of analog waveform or transmission. The line of code was called 2 binary, 1 Quaternary (2B1Q). A 2B1Q implementation of ISDN basic rate uses frequencies ranging from 0 (zero) to about 80,000 Hz, which has less attenuation and results in the desired loop reach of 18,000 feet. History about ADSL Line Codes Around the same time (1980’s decade), the industry recognized asymmetric attributes of the local loop that telephone companies had developed a strong interest in providing video entertainment services. This interest has been motivated by the desire to increase revenue through new services and recognizing that non-US cable television operators have started offering voice services over their plant coaxial cable. By late 1992, three line codes were emerging as

DSL – VDSL-based Video Service VDSL provides operators the ability to offer a multitude of digital video service that increases their phone deals and existing Internet services. VDSL has the capacity to support Digital Television Broadcast, Video on Demand, and HDTV over standard twisted-pair copper. In addition to digital video and Internet services, VDSL also supports interactive video services, Web TV, e-commerce, video conferencing, and video games, which is a set of services currently not available from cable operators or DBS. High-Speed Internet Providing access to high speed Internet is an essential value for home users, small businesses, hotels, institutions and other multi-site buildings. The Internet is growing at a phenomenal rate and this growth is the expansion of new and varied applications to take advantage of the increased availability of equipment, software, access, and users. These new applications require more resources than can be provided with the existing infrastructure, which limits the profit potential in providing these applications. While other DSL technologies such as ADSL and G.lite, can meet the limited requirements of Internet applications today. These systems will soon run out of bandwidth. However, VDSL has the capacity to support today”s applications with dining support emerging applications of tomorrow, creating new revenue growth opportunities, while preserving investment in DSL technology. As the Internet grows increasingly architecture backbone is replaced by ATM. ATM technology is the preferred Internet backbone FSAN to manage the growing burden to support daily operations and mission critical applications. The ATM architecture was chosen because it allows a single ATM network to be used to support all data transport, voice and video instead of delivering them to separate and incompatible networks. The combination of VDSL and ATM technology provides Internet services today in an architecture that supports the applications of tomorrow. Telephony Services A key service for every telco is the delivery of lifeline telephony services. One thing that has become universally expected is that no matter what, the phone will work. VDSL, like other DSL technologies, supports a lifeline POTS connection. This is a basic requirement that must be met by a telephony service provider. VDSL offers this feature and gives the telco opportunity to provide additional voice channels derivatives on the same pair of existing copper. The Voice over IP (VoIP) and Voice over ATM (VToA) technologies are providing standard quality telephony services over a digital network. Because ATM can also transport communications based on IP, ATM over VDSL will support both digital telephony standards. Although Voice over DSL (VoDSL) initiatives seek to develop a standard for carriage on flavors of DSL, bandwidth is always the question. Higher bandwidth VDSL provides more derived voice channels. Cable operators are starting to enter the market of voice using these technologies, but they face a major obstacle in providing Lifeline Services. The capacity of the new class of telecom operators offering comprehensive services to provide lifeline POTS along the derivative telephony, Internet access, and digital video services is a key advantage over cable and DBS operators. Deployment Scenarios The deployment of the full service access network is progressing with the deployment of fiber-based networks. The final architecture is fiber-to-the-home and business, but it will take a number of years and significant resources to implement. Deployment scenarios for today are the fiber-to-the-trade (FTTEx), fiber-to-theneighborhood (FTTN), FTTCab and FTTB. VDSL is only suitable for FTTEx, where customers are served within reach of the central exchange (CO). FTTN and FTTCab are suitable for standalone deployments, VDSL switch or as part of a New Digital Loop Carrier Generation (NGDLC). FTTB would bring fiber directly into a building like a multi-site unit (MDU) or business of the company and end the VDSL. Major VDSL2 Activity Following are the countries, which are using VDSL2. Taiwan Presently, 5-band 100/50Mbps and 30MHz 100/100M VDSL deployments occurring in high volume at NTT, UCOM, and KDDI. Softbank field-testing of FTTN VDSL systems is also happening currently. CHT 5-band 100/50Mbps 480k port VDSL are deploying currently. Korea Has been aggressively rolling out QAM VDSL for over three years. More than 75% coverage of the country with ADSL and VDSL. Will begin VDSL2 evaluating 30MHz − 100/100 systems in September. North America SBC Project Lightspeed to bring IPTV via FTTN VDSL systems to over 4M households in the next three years. Verizon deploying Fiber to the Premise (FTTP) and Fiber to the Cabinet (FTTCab) now. VDSL to Multi-Dwelling Units will have some volume in 2006. BellSouth field-testing VDSL systems. Bell South & AT&T are now expected to merge and therefore have a common VDSL BBA strategy around VDSL2. Europe Presently, Swisscom and Belgacom VDSL deployments are occurring in small volumes now. Deutsche Telecom 17MHz deployments on hold pending system issues. KPN and Telefonica deployed VDSL in 2007. Telecom Italia is in lab evaluation with VDSL DSLAMs at present. Other Regions PCCW in Hong-Kong Awarded Tender for ATM VDSL Deployments. China has done their second VDSL lab testing session. Singapore Telecom lab testing VDSL2 systems are being deployed. VDSL Access Deployment Models The following illustration describes the VDSL access deployment models. VDSL2 Key Features Following are the key features of VDSL2. DMT modulation Same as ADSL Bandwidth increased from 30 MHz ( 14x ADSL2+) Up to 4096 tones (8x ADSL+!) Worldwide Versatile Standard 8 Profiles defined for different services Different band plans for different regions Variety of PSDs to optimize spectral compatibility Support for a variety of Services Integrated Quality of Service features ATM as well as Ethernet payload Channel bonding for extended reach or rate VDSL2 − DMT (Discrete Multi-Tone) The concept of discrete multi-tone is − The frequency band is split into sub-channels equally spaced. Each sub-channel has data modulated on it using QAM. The number of bits allocated to a sub-channel depends on the SNR measured on this sub-channel. Tone Spacing ADSL2/2+/ VDSL2 8a,8b,8c,12a,12b,17a = 4.3125 kHz VDSL2 30a = 8.625 kHz Bin number × Tone spacing = Bin frequency For example − Bin 64 × 4.3125k = 276 kHz The advantage of this is

Discuss DSL Digital Subscriber Line (DSL) technology is a copper loop transmission technology, which satisfies bottleneck problems often associated with the last mile between the network and the service providers. This is an introductory tutorial, which covers the basics of the DSL Technology. Learning working make money

DSL – Useful Resources The following resources contain additional information on DSL. Please use them to get more in-depth knowledge on this. Useful Links on DSL − Wikipedia Reference for DSL. Useful Books on DSL To enlist your site on this page, please drop an email to [email protected] Learning working make money

DSL – Overview Digital Subscriber Line technology is a Copper Loop Transmission Technology, which satisfies bottleneck problems that are often associated with the last mile between the network and service providers. While DSL technology provides dramatic improvements in speed, (up to 8+ Mbps) compared to other network access methods, the true strength of DSL-based service opportunities lies in the actions like − Multimedia applications required by today”s network users. Performance and reliability. Economics. As shown in the following sample comparison chart, DSL-based services offer Performance Benefits for the Network Service Users when compared to other network access methods. In Addition, DSL-based services expand these operational improvements for public and private (Campus) operators. One of the compelling advantages of DSL technology is that it is the NSP and helps the Service Users to take full advantage of the existing infrastructure, layer two and layer three Protocols (such as Frame Relay, ATM and IP), and have reliable network services already entrusted to come. DSL can easily support advanced business-class services such as Voice over DSL (VoDSL) and new variants of proven and well-understood technologies such as the Frame Relay over DSL (FRoDSL). The latest generation of DSL equipment also offers end-to-end Service Level Management (SLM). For simplicity, in our discussion regarding business class DSL applications, we will group all of these under a new acronym − SLM-DSL. Learning working make money

DSL – ADSL Fundamentals In this chapter, we will discuss the fundamentals and standards of Asymmetric Digital Subscriber Line. ADSL Fundamentals To begin with, let us understand the following points. Discrete Multi-Tone (DMT) modulation used by all ADSL standards for a physical layer. Divide the frequency band into many small channels. QAM modulation on each channel. Different bits assigned to each channel in terms of SNR. ADSL Fundamentals System Block Diagram for PHY Following is the ADSL Fundamentals System Block Diagram for PHY. ADSL Standards The following table describes the ADSL Standards. Version Standard name Common name Downstream rate Upstream rate Approved in ADSL ANSI T1.4131998 Issue 2 ADSL 8.0 Mbit/s 1.0 Mbit/s 1998 ADSL ITU G.992.1 ADSL (G.dmt) 8.0 Mbit/s 1.3 Mbit/s 1999-07 ADSL ITU G.992.1 Annex A ADSL over POTS 12.0 Mbit/s 1.3 Mbit/s 2001 ADSL ITU G.992.1 Annex B ADSL over ISDN 12.0 Mbit/s 1.8 Mbit/s 2005 ADSL ITU G.992.2 ADSL Lite (G.lite) 1.5 Mbit/s 0.5 Mbit/s 1999-07 ADSL2 ITU G.992.3 ADSL2 12.0 Mbit/s 1.3 Mbit/s 2002-07 ADSL2 ITU G.992.3 Annex J ADSL2 12.0 Mbit/s 3.5 Mbit/s ADSL2 ITU G.992.3 Annex L RE-ADSL2 5.0 Mbit/s 0.8 Mbit/s ADSL2 ITU G.992.4 splitterless ADSL2 1.5 Mbit/s 0.5 Mbit/s 2002-07 ADSL2+ ITU G.992.5 ADSL2+ 24.0 Mbit/s 1.4 Mbit/s 2003-05 ADSL2+ ITU G.992.5 Annex M ADSL2+M 24.0 Mbit/s 3.3 Mbit/s 2008 2008 ADSL2++ (up to 3.75 MHz) ADSL4 52.0 Mbit/s ? 5.0 Mbit/s In development Annexure G.DMT G.992.1 Annex A − Full rate ADSL over POTs Overlapped Spectrum PSD Masks Non-overlapped Spectrum PSD Masks G.992.1 Annex B − Full rate ADSL over ISDN Overlapped Spectrum PSD Masks only, however, overlap is optional G.992.1 Annex C − Full rate ADSL in TCM-ISDN binder PSD Mask as for G.992.1 Annex A G.DMT PSDs The following illustration describes G.DMT PSDs. G.Dmt Performance The G.Dmt Performance can be understood by the following description. NSC = number of sub carriers Sub carrier spacing = Δ f = 4.3125 KHz Data symbol rate = 4.0 KHz Data rate = N * 4 * 8 Kbps (multiples of 32 Kbps) Bandwidth = NSC * Δ f Sample rate = 2* NSC *Δ f NSC 256 Total bandwidth 1.1 MHz Sample rate 2.2 MHz Maximum Date Rate ~12Mbps(down)/1.2Mbps (up) Maximum Reach 20kf Dial Tone Services While DMT was chosen as the official standard, systems based on the CAP have been used worldwide to implement many ADSL and a line of video sounds trials and commercial deployments, determine effectively the CAP as a de facto standard ADSL competition. Meanwhile, the threat of offering telephony services in the industry of cable television in the United States largely subsided. Globally, the tone video applications have increased, but continues to maintain interest. In many markets, they were difficult to justify the cost in relation to the widespread availability of cable TV and satellite TV. As a result, the video dial tone initiatives have largely disappeared in North America. The final standard for ADSL – approved by the International Telecommunication Union (ITU) (G.dmt or G.992) and ANSI (T1.413 Issue 2) – was, as mentioned earlier, a DMT-based system and is the basis of most new ADSL deployments today. Some vendors, however, continued to deploy PAC-based systems in their networks. Application Switch from Video to Data Throughout these long tone trial video dialing, the industry has come to recognize that many data applications were made asymmetrical. The best example of this is the internet. Typically, users send a small stream of data to a remote server, which requests the download of a data file, graphic, audio and video in particular. In response, the server starts sending the file data rate that can be supported over the network to the remote workstation. This transaction is extremely asymmetrical in nature. During this same time, the Internet has evolved into a completely new phenomenon, which is unheard of, when compared to the rate of the new subscribers to the Internet growth services. The biggest complaint of all users is that it took too long to upload files to the modem dial or even ISDN data rates. Therefore, a new need of services and new technology were soon married, and ADSL has been reoriented to support Internet access. Video has not completely disappeared as a request for DSL. However, video delivery over IP − using systems such as RealMedia or Windows Media – has become increasingly popular and sophisticated. Using compression systems such as MPEG-2 or new industry standard systems that allow even compression of the video, IP video delivery continues to be a viable application for DSL. Optimization for Data Services When the application was a bit synchronous video, the DSL line had to run at a specified line speed. However, the data can be operated at a wide range of speeds. The only effect is that slower speeds take longer to transport large files. Therefore, with data applications, we have the possibility of reducing the line speed to allow the service to be provisioned over longer lines. Both CAP and DMT transceivers have been modified to optimize the service on a loop basis and its implementation was called Adaptive Rate Digital Subscriber Line, or RADSL. RADSL technology supports the ability to allow the transceiver to automatically-increase the line speed to the highest achievable data rate, which can be achieved reliably over a given loop. Although this feature was designed primarily to simplify the service facility, it also gives service providers the possibility of a graceful degradation of service in case of degrading loop conditions. Today, there are other DSL technologies, which support the adaptation of rates. The service providers interested in this feature should examine the extent to which it is supported in different technologies. RADSL Standards As it can be seen, industry and technology have changed dramatically since the tone Video ADSL standards decision in March 1993. In recognition of this Working Group, T1E1 ANSI has established a standard known as ANSI TR59 RADSL. The FCC has specifically cited RADSL as a technology that is