About the Organization

Scom is a leading technology services provider, delivering business solutions to its principle customers. Scom delivers one of the industry's broadest portfolios of information technology and business process outsourcing services to customers in the industries. They are Different as they provide outstanding service, innovation and industry thought leadership.

As their customers' trusted business ally, Scom provides the best solutions for principles to maximize return on their Network investments. Its deep industry knowledge enables it to provide customers with innovative ideas that help them improve productivity and security. Scom deliver on its commitments, so customers can build strong relationships with their customers, achieve profitable growth and win in the marketplace.

Scom’s portfolio is built around innovative and dedicated offerings in maintenance and development, business process outsourcing, and infrastructure, including desktop services, hosting, storage and networking. We use our next-generation global delivery system to ensure high quality. This enables our customers to respond quickly to changing market dynamics and increase their competitiveness.

Scom is a 17-year-old IT Hardware, Networking, Customer Service oriented Company, headquartered at New Delhi. It has a pan-India presence through its own network of 26 offices. Business Partner to world famous Brands like HP, Lenovo, IBM for Computer Peripherals, PC, Consumer Electronics, and Enterprise Business. As far as Customer Service goes, Scom is Service Partner to topmost Telecommunications Brands in the country like Bharti Airtel Limited, HFCL Infotel Limited, and Reliance Communication Limited. It has built for itself a high credibility amongst its vast network and several million satisfied end users by offering value-for- money quality products supported by effective service and a consistent policy of transparent, fair and ethical dealings.

During the last 8 financial years, the company turnover has increased from INR 2 crore in 2001- 02 to INR 10 crore in FY 2010. The company has also been recognized by Principles through various rankings and awards received over the years.

The company has a strong technical Department in Delhi which is well-equipped with modern facilities and highly qualified engineers looking after developing systems for improvment in value-added services , specifications, benchmarking, quality up-gradation in service industry and technology development etc. This activity ensures that state-of-the-art products are offered as per the latest global standards.

As part of its diversification plan, Scom has added new business feathers in its cap."Trading Financial Securities" and "Materials Management". Mr.Vivek Bajaj having 20 years of experience in Financial Service & Securities have accepted the challenge and has joined Scom as Director Finance. With his experience in the portfolio, Scom has become Business Partner to Edelwise. Mr.S.C.Sehgal, having a vast experience of 40 years in Materials Management, consultant to NTPC, PMI, APGENCO, Ex-Advisor to Zimbabwe Electricity Board, has joined Scom Board of Directors for the same challenge. One of the most valuable assets of the company is its team of more than 500 employees with over 50000 man years of experience. The average age of a Scom employee is 7 years. Scom acknowledges the support and co-operation provided to the company by its dedicated and hardworking network of employees.

The vision of the company is to make itself a globally respected name and to improve the quality of services to the Customers and to provide a good working Environment and continuously upgrade skills of the employees.

Vision of the Organization:

"Without Vision, there's no Destination. Without Mission, there's no Purpose. Without Values, there are no Guiding Principles."

o "A Commitment to Excellence and Quality Services to our Customers and to provide a good Working Environment and to Continuously Upgrade Skills of the Staff through Training Programs." o Customer Delight. o Seek Technology and Trade Leadership. o Work with Quality People. o Enhance Work Culture and Environment. o Optimize Resource Management. o To Offer Services that, Empower our Customers to take control of their Financial Goals. o We will be Ethical, Sincere & Fair with our Clients. o We will Provide Outstanding Services. o We will strive to achieve Innovative and Dedicated Offerings. o We will be committed to Optimize Resource Management. o We will be committed towards creating an Operational Culture based on the highest level of Efficiency, Transparency, Team Work, Integrity and Common purpose".

Services offered:

o Telecommunication

. Fiber and Copper Termination . DSL broadband . Land line Installation . RF Installation

o Trading Financial Securities o Office Automation o Materials Management o Networking

. PRI and Lease Line Installation . WI-FI Installation

o Infocomm Training o Networking Surveillance Flowchart of the process:

Partners:

Lenovo, hp, ibm, molex dlink, edelweiss, airtel, alcatel lucent

INTRODUCTION DSL is a high-speed Internet service like cable Internet. DSL provides high-speed networking using existing twisted-pair telephone lines to transport high- data, such as multimedia and video, to service subscribers with the assistance of a broadband technology. DSL technology allows Internet and telephone service to work over the same phone line simultaneously without requiring customers to disconnect either their voice or Internet connections. The term xDSL covers a number of similar yet conflicting forms of DSL, including ADSL, SDSL, HDSL, RADSL, and VDSL. xDSL is growing and getting significant attention from customers and service providers because it promises to deliver high-bandwidth data rates to dispersed locations with relatively small changes to the existing telecom infrastructure.[1] xDSL provides dedicated, point-to-point, public network access services over copper wire on the local area between a network service provider (NSP’s) central office and the customer site, or on local loops created either within a building or a campus. DSL technology is attractive because it requires little to no upgrading of the existing copper infrastructure that connects nearly all populated locations in the world. In addition, DSL is inherently secure due to its point-to-point nature.

DSL Internet services are used primarily in homes and small businesses. DSL Internet service only works over a limited physical distance and remains unavailable in many areas where the local telephone infrastructure does not support DSL technology. DSL technology theoretically supports data rates of 8.448 Mbps, although typical rates are 1.544 Mbps or lower. Currently the primary focus in xDSL is the development and deployment of ADSL and VDSL technologies and architectures.

Overview: Alexander Graham Bell and Samuel Morse, who developed the idea that data could be transmitted through copper wire. they had no where they would actually lead. However, the principles had been laid. The technological race is a fast-paced. Improvements and developments are constantly being made. What once seemed to be amazing advances had became yesterday’s news. Has DSL () always moved at this speed?

Bell and Morse, were instrumental in developing a path for the ever-increasing volume of data transmitted over the Internet. In the late 1980s, Joseph Lechleider, father of broadband technologies demonstrated the possibility of sending broadband signals. He developed the idea of asymmetry (the A in ADSL), which suggested that a higher rate of data could be sent in one [2] direction. Putting it simply, this was the beginning of the move from analog to digital.

This was the time when ISDN was created as a first effort or this technology. Integrated Services Digital Network, is a system of digital phone connections which allows voice and data to be transmitted simultaneously. The result of this is that more data could be transmitted at the same time, thus creating more speed. Bringing ISDN technology to bear throughout the telephone network required an immense effort lasting more than a decade, consuming money and yielding a service that, was too little. The ISDN specification, built to deliver digital data at the now- unimpressive rate of 128 kbps, presumed brief data sessions with relatively slow transmission speeds, and supporting mainly for digital phone calls. At that time we can say nothing was best suited for the Internet, which scarcely existed as a consumer medium at the time of ISDN's introduction, which now emerges as the central force behind the broadband revolution.

John Cioffi at Standard University’s Department of Electrical Engineering, developed DMT (discrete multitone), a method of separating a DSL signal into 256 frequency bands or channels. Cioffi founded a company called Amati, who, in 1993, designed equipment to perform this task. And this equipment was dramatically better than its competitors in Bellcore testing and became the most common standard. DSL technology turns the historical telephone network into a high- speed broadband delivery instrument. In a way, DSL has revived a maturing business—that of using the telephone network to carry phone calls.

DSL was designed mainly for video. ADSL was a favorite choice as it provides the high downstream rates needed for streaming video. Video on Demand (VOD) was viewed as the next generation service supporting the next generation network from telephone companies around the world. Video on Demand was gave the telephone companies a way to compete with cable television providers, and ADSL was the technology to make it possible. However, with few exceptions, VOD has not proven to be as popular as was once predicted. Instead, the market for DSL has emerged much differently than was once expected. It was started being used device to access high-speed Internet on Personal Computers by corporate networks from residences and remote offices. Now, this PC user market has captured the attention of both cable TV providers and telephone companies, as both are furiously working to meet their needs.

The motivation of digital subscriber line technology was the Integrated Services Digital Network (ISDN) specification proposed in 1984 by the CCITT (now ITU-T) as part of Recommendation I.120, later reused as ISDN Digital Subscriber Line (IDSL). Employees at Bellcore (now Telcordia Technologies) developed Asymmetric Digital Subscriber Line (ADSL) and filed a patent in 1988[2] by placing wide-band digital signals above the existing baseband analog voice signal carried between telephone company telephone exchanges and customers on conventional twisted pair cabling facilities.[3] Consumer-oriented ADSL was designed to operate on existing lines already conditioned for BRI ISDN services, which itself is a switched digital service (non- IP), though most incumbent local exchange carriers (ILECs) provision Rate-Adaptive Digital Subscriber Line (RADSL) to work on virtually any available copper pair facility—whether conditioned for BRI or not. Engineers developed higher-speed DSL facilities such as High Digital Subscriber Line (HDSL) and Symmetric Digital Subscriber Line (SDSL) to provision traditional Digital Signal 1 (DS1) services over standard copper pair facilities.

A DSL circuit provides digital service. The underlying technology of transport across DSL facilities uses high-frequency sinusoidal modulation, which is an analog signal transmission. A DSL circuit terminates at each end in a modem which modulates patterns of bits into certain high-frequency impulses for transmission to the opposing modem. Signals received from the far-end modem are demodulated to yield a corresponding bit pattern that the modem retransmits, in digital form, to its interfaced equipment, such as a computer, router, switch, etc. Unlike traditional dial-up , which modulate bits into signals in the 300–3400 Hz baseband (voice service), DSL modems modulate frequencies from 4000 Hz to as high as 4 MHz. This frequency band separation enables DSL service and plain old telephone service (POTS) to coexist on the same copper pair facility. Generally, higher bit rate transmissions require a wider frequency band, though the ratio of bit rate to bandwidth are not linear due to significant innovations in digital signal processing and digital modulation methods. Early DSL service required a dedicated dry loop, but when the U.S. Federal Communications Commission (FCC) required ILECs to lease their lines to competing DSL service providers, shared-line DSL became available. Also known as DSL over Unbundled Network Element, this unbundling of services allows a single subscriber to receive two separate services from two separate providers on one cable pair. The DSL service provider's equipment is co-located in the same central office (telephone exchange) as that of the ILEC supplying the customer's pre- existing voice service. The subscriber's circuit is then rewired to interface with hardware supplied by the ILEC which combines a DSL frequency and POTS frequency on a single copper pair facility.

On the subscriber's end of the circuit, inline low-pass DSL filters (splitters) are installed on each telephone to filter the high-frequency "hiss" that would otherwise be heard, but pass voice (5 kHz and below) frequencies. Conversely, high-pass filters already incorporated in the circuitry of DSL modems filter out voice frequencies. Although ADSL and RADSL modulations do not use the voice-frequency band, nonlinear elements in the phone could otherwise generate audible intermodulation and may impair the operation of the data modem in the absence of low-pass filters.

TYPES OF DSL:

There are many variations of DSL, each aimed at particular markets, all designed to accomplish the same basic goals. Several modulation technologies are used by various kinds of DSL, although these are being standardized by the International Telecommunication Union (ITU ). Different DSL modem makers are using either Discrete Multitone Technology (DMT ) or Carrierless Amplitude Modulation ( CAP ). A third technology, known as Multiple Virtual Line MVL is another possibility.

ADSL :

ADSL, or Asymmetric DSL, is aimed at the residential consumer market. ADSL is called "asymmetric" because most of its two-way or duplex bandwidth is devoted to the downstream direction, sending data to the user.[3]ADSL provides higher data rates in the downstream direction, from the central office to the end user, than in the upstream direction, from the end user to the central office. Only a small portion of bandwidth is available for upstream requests. However, most Internet and especially graphics or multi-media demanding Web data need large downstream bandwidth, but user requests and responses are small and require little upstream bandwidth. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream. The high downstream bandwidth means that your telephone line will be able to bring motion video, audio, and 3-D images to your computer or hooked-in TV set. In addition, a small portion of the downstream bandwidth can be devoted to voice rather data, and you can hold phone conversations without requiring a separate line.[4]

CAPABILITY:

ADSL has ability to operate along with existing Plain Old Telephone Service (POTS) on a single pair of wires without disruption. POTS is the basic service that provides all phone lines with access to the Public Switched Telephone Network (PSTN). POTS provides the means for all voice-band related applications and technologies, such as , caller identification, call waiting, analog facsimile, analog modem, etc...

It can be also used without Splitters, G.lite or Universal ADSL and now also known as G.992.2 does not require a POTS splitter to be installed at the consumer's home or business. ADSL Lite provides bandwidth downstream up to 1.5 Mbps and upstream up to 512 kbps. ADSL Lite provides service up to a maximum range of 12,000 feet (about 2.0 miles) from the central office

Three information channels—a high-speed downstream channel, a medium-speed duplex channel, and a basic telephone service channel are created when an ADSL modem is connected. The basic telephone service channel is divided from the digital modem by filters, thus guaranteeing uninterrupted basic telephone service, even if ADSL flops. The high-speed channel ranges from 1.5 to 6.1 Mbps, and duplex rates range from 16 to 640 kbps. Each channel can be sub multiplexed to form multiple lower-rate channels. ADSL modems provide data rates consistent with North American T1 1.544 Mbps and European E1 2.048 Mbps digital hierarchies (see Figure 15-2) and can be purchased with various speed ranges and capabilities. The minimum configuration provides 1.5 or 2.0 Mbps downstream and a 16 kbps duplex channel; others provide rates of 6.1 Mbps and 64 kbps duplex. Products with downstream rates up to 8 Mbps and duplex rates up to 640 kbps are available today ADSL modems accommodate Asynchronous Transfer Mode (ATM) transport with variable rates and compensation for ATM overhead, as well as IP protocols. Downstream data rates depend on a number of factors, including the length of the copper line, its wire gauge, presence of bridged taps, and cross- coupled interference. Line attenuation increases with line length and frequency and decreases as wire diameter increases.

FREQUENCY ALLOCATION:

ADSL uses Frequency Division (FDM) to separate frequency bands, referred to as the upstream and downstream bands. The upstream band is used for communication from the end user to the telephone central office. The downstream band is used for communicating from the central office to the end user. With standard ADSL (annex A), the band from 25.875 kHz to 138 kHz is used for upstream communication, while 138 kHz – 1104 kHz is used for downstream communication.

Fig. Process of Frequency Division Multiplexing