Overview of Broadband Access Technology PDF

JTO Ph-II DNIT Overview of Broadband Access Technology 1 OVERVIEW OF BROADBAND ACCESS TECHNOLOGY 1.1 LEARNING OBJECTIVES The main objective of this chapter is to build up the following  To understand what is Broadband  To understand the need of...

JTO Ph-II DNIT Overview of Broadband Access Technology 1 OVERVIEW OF BROADBAND ACCESS TECHNOLOGY 1.1 LEARNING OBJECTIVES The main objective of this chapter is to build up the following  To understand what is Broadband  To understand the need of broadband  To familiarize with the various broadband technologies  To familiarize with Broadband Network 1.2 INTRODUCTION With the evolution of computer networking and packet switching concept a new era of integrated communication has emerged in the telecom world. Rapid growth of data communication market and popularity of Internet, reflect the needs of enhanced infrastructure to optimize the demand of traffic. Integration of telecom and computer networking technology trend has further amplified the importance of telecommunications in the field of information communication. It becomes a tool for the conveyance of information, and thus can be critical to the development process. Telecommunications has become one of the most important infrastructures that are very essential to the socio-economic well being of any nation. As the Internet market continues to explode, demand for greater bandwidth and faster connection speeds have led to several technological approaches developed to provide broadband access to all consumers. The demand for high-speed bandwidth is growing at a fast pace, driven mostly by growth in data volumes as the Internet and related networks become more central to business operations. The rapid growth of distributed business applications, e-commerce, and bandwidth-intensive applications (such as multimedia, videoconferencing, and video on demand) generate the demand for bandwidth and access network. A concept of broadband services and the means of access technologies to bridge the customer and service provider is emerged out through out the world. "Broadband" refers to high-speed Internet access. Broadband Solutions represent the convergence of multiple independent networks including voice, video and data into a single, unified, broadband network. 1.3 DEFINITION OF BROADBAND Broadband is the nonspecific term for high-speed digital Internet access. To state the obvious, ‗broadband‘ indicates a means of connectivity at a high or ‗broad‘ bandwidth. There are the various ways to define the broadband: -  Term for evolving digital technologies that provide customers a high-speed data network connection  Provides signal switched facility offering integrated access to voice, data, video, and interactive delivery services  The Federal Communications Commission (FCC) defines broadband as an advanced telecommunications capability JTO Ph-II DNIT Version 3.0 Aug 2021 Page 2 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology  Delivers services & facilities with an upstream and downstream speed of 200 Kbps or more. Range varies from 128 Kbps to 100 Mbps. In fact there is no specific International Definition for Broadband In India, Department of Telecommunications had issues a Broadband policy in 2004. Keeping in view the present status, Broadband connectivity is defined at present as: - ―An ‗always-on‘ data connection that is able to support interactive services including Internet access and has the capability of the minimum download speed of 512 kilo bits per second (kbps) to an individual subscriber from the Point Of Presence (POP) of the service provider intending to provide Broadband service where multiple such individual Broadband connections are aggregated and the subscriber is able to access these interactive services including the Internet through this POP. The interactive services will exclude any services for which a separate license is specifically required, for example, real-time voice transmission, except to the extent that it is presently permitted under ISP license with Internet Telephony. It reflects that: -  One of the latest trends in enhancing communication systems involves broadband technology  Broadband refers to greater bandwidth-or transmission capacity of a medium  Broadband technology will allow for high-speed transmission of voice, video, and data over networks like the Internet 1.4 IMPLEMENTATION OF BROADBAND To Strengthen Broadband Penetration, the Government of India has formulated a Broadband Policy whose main objectives are to:-  Establish a regulatory framework for the carriage and the content of information in the scenario of convergence.  Facilitate development of national infrastructure for an information based society.  Make available broadband interactive multimedia services to users in the public network.  Provide high speed data and multimedia capability using new technologies to all towns with a population greater than 2 lakhs.  Make available Internet services at panchayat (village) level for access to information to provide product consultancy and marketing advice.  Deploy state of art and proven technologies to facilitate introduction of new services.  Strengthen research and development efforts in the telecom technologies. NEED OF BROADBAND The concept of socio economy has an important role in the field of communication of data, audio, video, speech or any other kind of application. It is an era of CAPEX and OPEX. Service providers and customers both are interested in economy with fastest tool of communication with more throughput. Traditional circuit switching network are not JTO Ph-II DNIT Version 3.0 Aug 2021 Page 3 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology supporting the effective fast communication for new applications. This has emerged out with the evolution of packet switching network. Communication of data for various applications is feasible to carry with different throughput. The service provider converged voice and data network promises to be implemented as nodes in a neighborhood or remote switches in regional locations. The Internet, e-mail, web sites, software downloads, file transfers: they are all now part of the fabric of doing business. But until now, it has not been possible for businesses to fully take advantage of the benefits that technology can truly deliver. The reason for this is a simple one - a lack of bandwidth. Even for small businesses, narrowband dial-up access is no longer sufficient. It simply takes too long to do basic tasks, like downloading a large file, and is increasingly being recognized as insufficient and inconvenient. Kim Maxwell in his book-"Residential Broadband: An Insider's Guide to the Battle for the Last Mile" has grouped potential residential broadband applications into three general categories: "professional activities" (activities related to users' employment), "entertainment activities " (from game playing to movie watching), and "consumer activities " (all other non- employment and non-entertainment activities). as follows: PROFESSIONAL ACTIVITIES:  Telecommuting (access to corporate networks and systems to support working at home on a regular basis)  Video conferencing (one-to-one or multi-person video telephone calls)  Home-based business (including web serving, e-commerce with customers, and other financial functions)  Home office (access to corporate networks and e-mail to supplement work at a primary office location) ENTERTAINMENT ACTIVITIES:  Web surfing (as today, but at higher speeds with more video content)  Video-on-demand (movies and rerun or delayed television shows)  Video games (interactive multi-player games) CONSUMER ACTIVITIES:  Shopping (as today, but at higher speeds with more video content)  Telemedicine (including remote doctor visits and remote medical analyses by medical specialists)  Distance learning (including live and pre-recorded educational presentations)  Public services (including voting and electronic town hall meetings)  Information gathering (using the Web for non-entertainment purposes)  Photography (editing, distributing, and displaying of digital photographs)  Video conferencing among friends and family JTO Ph-II DNIT Version 3.0 Aug 2021 Page 4 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology These applications have different bandwidth requirements, and some of them are still out of reach today. For example, all of the "professional" activities will likely be supported with less than 1.0 Mbps of bandwidth. Similarly, web surfing and home shopping will be supported with less than 1.0 Mbps of bandwidth. Movies and video, however, demand more bandwidth. Feature length movies can probably be delivered with 1.5 Mbps of bandwidth, but broadcast quality video will probably require more— perhaps as much as 6.0 Mbps. Moreover, if high definition television ("HDTV") is widely accepted as a new broadcast standard, that quality of video would require almost 20.0 Mbps of bandwidth — much higher than the current broadband technologies will support. Thus, although the technology is moving toward flexible, high-quality video-on-demand, the necessary speed is probably still more than a few years away from becoming a reality. The Internet is poised to spin off thousands of specialized broadband services. The access network needs to provide the platform for delivery of these services. Following are the various applications or services, which are very popular in society and needs broadband connectivity: - VIRTUAL NETWORKS The private virtual networks (LAN/WAN) can be used in an ample variety of multimedia services, like bank accounts and central offices. EDUCATION BY DISTANCE Education will not have any limits to reach from source to destination. Along with the traditional school a concept of remote leaning center is emerged out and popular for various courses. There is no limit of distance, area or location in such distance learning. The student situated in the remote station can intervene directly to his class with a double system via videoconference, whilst this happens, simultaneously, the file ex change TELEWORK Organization firm workers that incorporate communication systems via satellite, can work remotely connecting directly to their head offices Internet by a high speed connection that permits users to work efficiently and comfortable. TELEMEDICINE Doctors situated in different clinics can stay in contact and consult themselves directly to other regional medical centers, using videoconference and the exchange of high quality images, giving out test results and any type of information. Also rural zone can have the opinion of specialists situated in remote hospitals quickly and efficiently. ELECTRONIC COMMERCE Electronic commerce is a system that permits users to pay goods and services by Internet. Thanks to this service, any person connected to the network can ad quire such services with independence from the place that he is situated and during the 24 hours, simply using a portable computer. JTO Ph-II DNIT Version 3.0 Aug 2021 Page 5 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology 1.5 TECHNOLOGY OPTIONS FOR BROADBAND SERVICES Communication of data with different throughput is feasible by following technologies: -  Narrow Band 2.4 kbps – 128kbps  Broadband 256kbps..512kbps – 8000kbps  LAN 1000kbps – 100Mbps / Giga Ethernet Various Access Technologies are used for the delivery of broadband services. Broadband communications technology can be divided broadly in to following categories: -  Wireline Technology  Wireless Technologies Service providers according to available technology and access provide the broadband services to customers. The access technologies that are adopted by the services providers are mainly Optical Fiber Technologies, DSL on copper loop, Cable TV Network, Satellite Media, cellular and fixed wireless, Terrestrial Wireless etc. Technology options for broadband services may be classified according to the mode of access. WIRE LINE TECHNOLOGIES INCLUDE  Digital Subscriber Lines (DSL) on copper loop  Optical Fiber Technologies  Cable TV Network  PLC (Power Line Communication) WIRELESS TECHNOLOGIES INCLUDE  Satellite Media  Terrestrial Wireless  3G Mobile  Wi-Fi (Wireless Fidelity)  WiMax  LMDS and MMDS  FSO (Free Space Optics) JTO Ph-II DNIT Version 3.0 Aug 2021 Page 6 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology 1.6 BROADBAND NETWORK The broadband services reached to customer from the three providers. Basically these are Service Provider, Network Provider and Access Provider. The role of Network Provider is to provide the services offered to customer through the access extended by Access Provider. There are various types of networks which are capable of transmitting and managing the broadband traffic to desired nodes or locations. Wireline access technology through DSL, Fiber, Cable etc are generally adopts:  IP based Network  ATM Network Wireless access technology through Wi-Fi, Wi-Max. 3G mobile etc provides wireless access to ingress point of any core network any migrates to Internet world. 1.7 BROADBAND TECHNOLOGIES USED IN ASIAN COUNTRIES Broadband technologies go through two stages of development in Asian countries. In the early stage, sharp technological divisions exist among players due to regulatory constraints. There are various mode of access used by service providers in this field. Following was the beginning scenario in various countries like Hong Kong, Malaysia, Indonesia, India and Singapore: -  Basic Telecom service providers adopted the use of ISDN/DSL  CATV operators use cable modems  Competitive players use wireless technologies. In the later stage of development, technological divisions are shaped by geography and infrastructure. The broadband started establishing and due to a progressive regulatory framework it has matured in the market. In the countries like Korea and Philippines service providers employ several technologies for the broadband in their networks.  DSL and cable modems are used where the PSTN and CATV are in place.  Where rainfall is light, an LMDS is used to serve densely populated areas with little infrastructure and unwired business districts.  Satellite is used to service rural areas where population densities are low Once newer technologies are available in the market, ISDN becomes relatively less important. Established telephone companies are calculating the economics of converting the Last Mile of existing networks to all-digital systems. Hong Kong and Singapore citizens already have broadband access, such as movies on demand, through their local telecom network. Cable-TV operators, too, are venturing into high-speed Internet access through modified networks and end-user "cable modems." Advances in wireless communications means that people starts surfing the net with cell phones at speeds comparable to or greater than current home access. ADSL TECHNOLOGY OVERVIEW JTO Ph-II DNIT Version 3.0 Aug 2021 Page 7 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology xDSL Refers collectively to all types of digital subscriber lines, in which the two main categories: the asymmetric DSL (ADSL) and the symmetric DSL (SDSL). Other important types of xDSL technologies are High-data-rate DSL (HDSL) and Very high DSL (VDSL). xDSL is technology backed by telephone companies to provide next generation high bandwidth services to the home and business using the existing telephone cooper cabling infrastructure. xDSL to the home over existing phone lines promises bandwidths up to theoretically 8.448 megabits per second and more, but distance limitations and line quality conditions can reduce the data rate. xDSL technologies uses a greater range of frequencies over the telephone cable than the traditional telephone services have used. This in turn allows for greater bandwidth with which to send and receive information, enabling for example continuous transmission of motion video, audio, and even 3-D effects. xDSL technology has evolved greatly over the past few years, and is still in development toward achieving even a greater bandwidth as demand rises. Driving this market is the competition from competing access providers for the consumers hard earned cash. HISTORY Traditional phone service (sometimes called POTS for "plain old telephone service") connects our home or small business to a telephone company office over copper wires that are wound around each other and called twisted pair. Traditional phone service was created to let you exchange voice information with other phone users and the type of signal used for this kind of transmission is called an analog signal. An input device such as a phone set takes an acoustic signal (which is a natural analog signal) and converts it into an electrical equivalent in terms of volume (signal amplitude) and pitch (frequency of wave change). That's why our computer has to have a modem - so that it can demodulate the analog signal and turn its values into the string of 0 and 1 values that is called digital information. Because analog transmission only uses a small portion of the available amount of information that could be transmitted over copper wires, the maximum amount of data that you can receive using ordinary modems is about 56 Kbps (With ISDN, which one might think of as a limited precursor to DSL, you can receive up to 128 Kbps) The ability of our computer to receive information is constrained by the fact that the telephone company filters information that arrives as digital data, puts it into analog form for our telephone line, and requires our modem to change it back into digital. In other words, the analog transmission between our home or business and the phone company is a bandwidth bottleneck. HOW DOES DSL WORK xDSL technology assumes digital data does not require change into analog form and back. Digital data is transmitted to our computer directly as digital data and this allows the phone company to use a much wider bandwidth for transmitting it to you. Meanwhile, if one chooses, the signal can be separated so that some of the bandwidth is used to transmit an analog signal so that you can use your telephone and computer on the same line and at the same time. JTO Ph-II DNIT Version 3.0 Aug 2021 Page 8 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology In detail, xDSL utilizes more of the bandwidth on copper phone lines than what is currently used for plain old telephone service (POTS). By utilizing frequencies above the telephone bandwidth (300Hz to 3,400Hz), xDSL can encode more data to achieve higher data rates than would otherwise be possible in the restricted frequency range of a POTS network. Thanks to Advances in DSP technology combined with innovation in algorithms and coding methods over the past few years, bandwidth utilization has increased even more (varying from under 100kHz for narrow-band ISDN to over 10MHz for VDSL). In order to utilize the frequencies above the voice audio spectrum, xDSL equipment must be installed on both ends and the copper wire in between must be able to sustain the higher frequencies for the entire route. This means that bandwidth limiting devices such as loading coils must be removed or avoided. 1.8 MODULATION TECHNIQUES (LINE CODES) QAM and CAP modulation QAM ( Quadrature Amplitude Modulation) also known as I&Q modulation, is a combination of amplitude modulation (data is represented by differing amplitudes) and phase shift keying (data is represented by shifting each wave relative to the wave that came before it). In a QAM signal, there are two carriers, each having the same frequency but differing in phase by 90 degrees (one quarter of a cycle, from which the term quadrature arises). One signal is called the I signal, and the other is called the Q signal. Mathematically, one of the signals can be represented by a sine wave, and the other by a cosine wave. Each of the two carriers are modulated via two separate balanced modulators (BM), and then combined (algebraically summed) at the source for transmission. At the destination, the carriers are separated; the data is extracted from each, and then combined into the original modulating information. CAP (Carrierless amplitude/phase) modulation, which was the original approach for DSL (and the choice of many modems manufacturers in the past), produce the same form of signal as QAM, without requiring in-phase and quadrature components of the carrier to first be generated. Figure 1: Conceptual CAP transmitter The Constellation Encoder maps the incoming data into two stream a1..an and b1..bn. Those streams are then passed to the two filters which are designed so that their impulse response form a hilbert pair( i.e. one signal is phase-shifted by 90 degree regarding the other). JTO Ph-II DNIT Version 3.0 Aug 2021 Page 9 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology CAP splits the data into two bit streams and alters both symbol rate and modulation levels to change the bit rate, causing modems to be symbol rate adaptive to varying line condition. The carrier itself is suppressed before transmission (it contains no information, and can be reconstructed at the receiver), hence the adjective carrierless. CAP also uses frequency division multiplexing to eliminate the need for echo cancellation techniques. Another advantage is the cost element implementing the technology, which is relatively low. DMT MODULATION DMT ( Discrete MultiTone ) is a version of multicarrier modulation in which the data is distributed over a large number of subcarriers, or channels, each of which uses a form of QAM modulation. DMT modems divide the downstream bandwidth into 256 channels of 4 kHz each, and can transmit up to 15 bits/Hz in each channel. The modems can adapt to different impairments in different lines by evaluating the signal-to-noise ratio (SNR) in each subchannel and sending more data in those with higher quality. Figure 2: Conceptual DMT transmitter The input data is buffered, and each bit is assigned or mapped into one of N complex (QAM) multi-level sub-channel symbols by the DMT symbol encoder. Since these are complex numbers, they can be treated as discrete frequency-domain representation of the signal. using IFFT we can convert it to its time-domain representation (the receiver will use FFT to convert it back). The resulting time domain function is then sent serially through the D/A converter and line filter. DMT upstream and downstream channels overlap; therefore, echo cancellation techniques are needed. Discrete Wavelet Multitone (DWMT), a developmental variant of DMT, will provide better sub-channel isolation by using a digital wavelet transform instead of the Fourier transform used in standard DMT. DMT xDSL transceivers based on the Standard have been proven to provide high-grade performance in the field, are more reliable, and considered the preferred Modulation Technique for DSL. FMT MODULATION FMT ( Filtered MultiTone) is a multicarrier modulation scheme which can be viewed as a combination of the other two methods. The modulation is achieved by splitting the data into several streams, each of them applied to one of the inputs of a filter-bank. Because of implementation complexity, the number of channels is considerably less than in DMT. JTO Ph-II DNIT Version 3.0 Aug 2021 Page 10 of 103 For Restricted Circulation JTO Ph-II DNIT Overview of Broadband Access Technology Figure 3: Conceptual FMT transmitter The input goes through an IFFT module, and then filtered by an FIR filter. At the end it goes serial using P/S converter. one of its main advantages is that the frequency band provided is better utilized in the border parts of the spectrum designed for individual transmission direction, where in the case of DMT losses in the transmission rate occur. The out of band emission is eliminated almost completely.FMT plays the rule of a strong candidate for the VDSL modulation method. 1.9 CONCLUSION In past decades we witnessed the rapid development of global communication infrastructure and the explosive growth of the Internet, accompanied by ever-increasing user bandwidth demands and emerging multimedia applications. These dramatic changes in technologies and market demands, combined with government deregulation and fierce competition among data, telcom, and CATV operators, have scrambled the conventional communication services and created new social and economic challenges and opportunities in the new millennium. To meet those challenges and competitions, current service providers are striving to build new multimedia networks. The most challenging part of current Internet development is the access network. As an integrated part of global communication infrastructure, broadband access networks connect millions of users to the Internet, providing various services, including integrated voice, data, and video. As bandwidth demands for multimedia applications increase continuously, users require broadband and flexible access with higher bandwidth and lower cost. A variety of broadband access technologies are emerging to meet those challenging demands. While broadband communication over power lines and satellites is being developed to catch the market share, DSL (digital subscriber line) and cable modem continue to evolve, allowing telecom and CATV companies to provide high-speed access over copper wires. The term broadband commonly refers to high-speed Internet access that is always on and faster than the traditional dial-up access. Broadband includes several high-speed transmission technologies such as: Digital Subscriber Line (DSL), Cable Modem. JTO Ph-II DNIT Version 3.0 Aug 2021 Page 11 of 103 For Restricted Circulation