Broadband services are used by Telecom Companies worldwide to leverage their existing investment in copper in the local loop. Copper as a last-mile delivery medium has the advantage of near-universal penetration, and local Telecom Companies are increasingly eyeing broadband services on it as a means of hitting back at cable operators who have begun infringing on their turf by their bundled Internet offerings.
This article attempts to demystify the basic technologies involved in broadband delivery, the GOIs attempts to promote broadband usage in the country, and BSNLs broadband plans as part of its ambitious NIB-II project.
To state the obvious, broadband indicates a means of connectivity at a high or broad bandwidth. In India, TRAI has defined broadband as any connectivity delivered to the end user at a bandwidth greater that 256 kbps. (So that immediately excludes the popular DIAS services offered by BSNL at many places).
Why is bandwidth so important and how to estimate how much bandwidth is required for a particular application? A small example below will help illustrate the concept.
Assuming you wish to receive a VCD quality transmission ( incidentally, this is also the quality offered by low cost desktop videoconferencing applications ) over your broadband connection, the maths is:
Of course, the above is raw transmission rate modern technologies use advance compression algorithms to reduce the data rate to a great extent.
The problem of the last mile
While telecom companies have adequate high speed OFC infrastructure to connect their Exchanges and switches, the same does not hold good with the legacy fixed line customers who are connected, however adequately for voice communication, by good old copper. How to deliver the broadband content over this seemingly low bandwidth medium was the question till recently, when advanced Line coding and compression technologies solved the problem.
2.1 The Misunderstood Copper
It has been the general perception that copper is no good for anything other than speech communications of the analog variety. However, the blame for the low bandwidth rests with the telephone system rather than with the medium. The telephone system filters the voice to a range of 400 Hz to 3.4 KHz, thereby rendering the local lead useless for even good quality sound transmission. And people blame the poor copper !
When data transmission was attempted over non-exchange lines using traditional line coding mechanisms like AMI (Alternate Mark Inversion), a good bandwidth could not be achieved because these mechanisms corrupt the spectrum and cause interference between the pairs in a copper cable bundle. To overcome this , alternative technologies were devised which performed the line coding and transmission in such a way that the interference was minimized, thereby enabling much higher frequencies to be transmitted. And the mother of all technologies was DSL.
2.2 Broadband over copper: the DSLs
DSL stands for Digital Subscriber Loop.
The diagram below shows how DSL modulates the Line Spectrum. Data Signal is sent at a frequency higher that the Voice (3.4 Khz) frequency.
There are various technologies spawned off from DSL which perform to different expectations:
n DSL: Digital Subscriber Line
n SDSL: Single Line Digital Subscriber Line
n ADSL: Asymmetric Digital Subscriber Line
n HDSL: High data rate Digital Subscriber Line
n VDSL : Very High data rate Digital Subscriber Line
n IDSL: ISDN Digital Subscriber Line
These technologies offer differing bandwidths over different distances. The table below shows a comparison of their capabilities:
Of all the mechanisms outlined above, Asymmetric Digital Subscriber Loop (ADSL) has found favour as a broadband delivery mechanism, in view of its high downstream bandwidth. Downstream refers to data flowing from the service provider to the user. Most of the popular applications, like web browsing, video streaming, FTP downloads, etc., require much higher downstream bandwidth than upstream bandwidth. ADSL manages to extract high data rates in this direction. The distance limitations for ADSL are shown below:
Range in feet
With all the local telecom companies edging closer to the customer with their distributed access mechanisms like DLCs and RSUs, the above distances lie well within the range of most customer premises, and thus broadband delivery can be quite effective, with a richer user experience.
3.1 Multiplexing Voice and Data: DSLAM
The DSL Access Multiplexer, popularly known as DSLAM, is employed by the Telecom Companies to code the subscriber line with the broadband data content. Once the ADSL copper line reaches the customer, some customer premises equipment (CPE) has to be employed to separate the voice and data signals.
In many cases the Splitter function is combined within the DSL Modem CPE equipment, which is also known sometimes as a Set-top Box.
Several interesting services can be provided in an Integrated manner by the broadband service provider. Some of these are:
n High Speed Internet Services
n Video on Demand
n Multicast Video Streaming
n Interactive e- Learning
n Interactive Gaming
High speed Internet Services refer to always-on fast Internet access.
Video on Demand enables the user to select from an online library of content and select any of the available choices for viewing at a convenient time. This is similar to borrowing a Video for viewing .
Multicast video streaming is similar to cable or terrestrial broadcast the user can join at any time but the stream begins and ends at the preappointed times.
Interactive e-learning can consist of electronic classrooms with 2-way and multi-way communication between teachers and students.
Interactive gaming enables multiple players to play online games pitted against each other or against computers, through gaming servers employed by gaming content providers.
Needless to say, all these services require the service provider to have strong tie-ups with the various content providers. After all, what is hardware without usable software?
Broadband services in India have not yet really taken off because none of the major Telcos has been able to rollout such services in a really big way so far. Broadband penetration is, of course, dependent upon PC penetration as a major factor. India lags behind other major countries of the region by a substantial margin, as the following table will show.
The Confederation of Indian Industry ( CII) has envisioned some penetration targets for India over the years. They are :
The GOI is making great attempts to create a conducive environment for promoting Broadband services in the country. The GOI has formulated a Broadband Policy whose main objectives are to:
6.1 Broadband Policy
n Establish a regulatory framework for the carriage and the content of information in the scenario of convergence.
n Facilitate development of national infrastructure for an information based society.
n Make available broadband interactive multimedia services to users in the public network.
n Provide high speed data and multimedia capability using new technologies to all towns with a population greater than 2 lakhs.
n Make available Internet services at panchayat (village) level for access to information to provide product consultancy and marketing advice.
n Deploy state of art and proven technologies to facilitate introduction of new services.
n Strengthen research and development efforts in the telecom technologies.
6.2 Broadband enabling regulations
Some of the regulations proposed to achieve this end are listed below.
n Promoting of facility-based competition by lowering market entry barriers.
n Reducing charges for Rights of Ways (ROW).
n Permitting infrastructure sharing among different service providers for optimum utilization.
n Allowing the captive infrastructure of utility companies to be used for public broadband service.
n Reducing the bottleneck in last-mile access by permitting deployment of alternative technologies like Cable TV network, Wireless etc.
n Unbundling of local loop for DSL-based services.
6.3 Liberalized Licensing Regime
The GOI has created a simplified regime for rollout of Broadband services:
n Same as Internet Service Providers (ISP) License.
n The most liberal licensing regime.
n Unlimited competition (190 ISPs operational, 388 Licenses signed).
n No entry fee, Licence fee, Contribution to USF
n Can have their own International gateway
n FDI limit (100% for non-gateway service provider, 49% for International gateway service provider)
n Can use BSOs Infrastructure.
n High speed WLL (144 Kbps) permitted for BSOs.
n A liberal V-SAT licensing policy (upto 2Mbps).
With the NIB II project, BSNL is planning to rollout Broadband services in a big way across the country. The earlier forays in this regard did not really take off because of the inability of the franchisee to kickstart the equipment procurement and installation. However, with the current plans under the NIB-II project, BSNL will still be in a position to become the number one player in the segment in the country with its nation-wide rollout.
7.1 Broadband Services proposed to be rolled out
The following services are proposed to be rolled out on the hardware and software platforms provided by NIB-II:
n High Speed Internet Access
1 Mbps Upstream
8 Mbps Downstream
n Video Streaming
n Video Conferencing
n Interactive Gaming
n Point-to-Point Data Network on IP
7.2 BSNLs Objectives
BSNL has undertaken this project with the following objectives:
Ø To utilize to the maximum BSNLs existing infrastructure
40 Million BSNL Customers on Cu
Large scale deployed Fibers in Access & Core network
Deployed DLC Systems on Fiber
Ø To increase the footprint across the Country to provide Access Country Wide
Ø To provide Value Added Services (Video, Broadband Data in addition to Voice) to accelerate development and growth.
BSNL has envisioned that the Broadband services rolled as part of the ambitious NIB-II project will be
n used for high speed Internet connectivity and shall be the primary source of Internet bandwidth
n used for connecting broadband customers to the MPLS VPN through the BRAS.
n used for connecting dial VPN customers to the MPLS VPN through the Narrowband RAS.
7.3 Broadband Services in NIB-II : The Network
The following are the significant network elements for Broadband:
Ø Broadband Remote Access Server (BRAS or BBRAS)
This is the device which acts as the gateway granting customers access to the network. It offers the following services:
Some salient features of the BBRAS are:
Ø Aggregation Switch
The subscriber connections from the DSLAMs are aggregated through this before being passed on to the core router. This again is implemented in two tiers, with a tier1 switch aggregating traffic from multiple tier-2 switches.
7.4 Customer Services
The system proposed to be deployed had provisioning- related features which allow different services to be offered to the customers on demand. Of particular interest is the Subscriber Services Selection System (SSSS), which offers the flexibility to provide many ways of revenue-enhancing application service offerings via the ADSL network, with the following features:
« Tiered ISP Access
(such as Bronze, Silver, Gold Access)
« Video Conferencing
(reserve higher BW for scheduled videoconferencing)
« Streaming Audio or Video
(selection of audio or video )
« Outsourced business Application
(such as Human Resource Application, Database Application or Expense reporting)
The introduction of Broadband services is expected to usher in a true era of convergence and introduce a degree of seamlessness between the work and home environment that has never been possible before. Broadband services such as the one proposed by BSL will enable the local telecom companies to retain a foothold in the segment which has seen threats from new entrants like cable TV companies, Power supply carriers, and even gas pipeline companies. And with their traditional expertise in delivering and managing services at the customers premises, the telecom companies look slated to outstrip these competitors in this arena as well.
This article is based on a technical lecture delivered by the author at IETE Pune Chapter on 30-07-2004. The article was cobbled together from information gleaned from predominantly BSNL sources, as well as from the Internet. The author wishes to acknowledge Shri Dhakar, DE(STP) for the NIB-II related information, and Shri D.M.E Buddhan, DGM(DN) Bangalore for the inputs on the GOI plans and initiatives, the SSSS, etc. Finally, thanks to those who have read patiently to reach this point in the article.
Apologies for all errors and omissions. Suggestions are welcome on firstname.lastname@example.org