The Technology Options

Most CIOs are unable to follow the road map of their Internetstrategies as getting bandwidth in India can take anywhere between three to sixmonths. Even after they do get those fat pipes, reliability remains a majorproblem. Though the situation has improved with aggressive gateway plans ofISPs, a lot remains to be achieved.

On Internet access depends the other value-added servicesthat ISPs are planning to provide. In India, Internet access started withdial-up, ISDN, and leased-line. Leased-lines are considered to be the mostpreferred for corporates. But many ISPs have also started providing Internetover cable, satellite, and DSL technologies. Newer technologies like LMDS andMMDS still have a long way to go before corporates can decide what to opt forand what not to.

Dial-Up

It is the most popular and the cheapest way to accessInternet. It requires only a PC, a modem, and a telephone connection. Themaximum bandwidth that one can get is 56 Kbps, but even in the best of thenetworks it is difficult to get more than 28 Kbps. A better infrastructuredefinitely helps in providing a better service by the ISP.

ISDN

ISDN provides digital service typically in increments of 64Kbps. Its usage has increased with increase in the Internet usage. It uses 2B+DChannels. and comes in two modes–64 Kbps and 128 Kbps. To access this service,a corporate user has to get an ISDN link from the basic service provider that isconnected to the ISDN modem and in turn is connected to the PC for accessingInternet. The advantage here is that one can access Internet on one channelwhile make or receive voice calls on the other.

Leased-Line

This is a cost-effective Internet access solution offered bya majority of ISPs to corporates. The corporates can receive high-speed Internetconnectivity and pay for the bandwidth according to the usage. Considered to bethe more reliable network, corporates can get a leased-line from the basicservice providers. Leased-lines come in 64 Kbps and its multiples–124, 256,512 Kbps.

Internet-over-Cable

It allows Internet access over existing cable TV networkeither through PC, cable modem or TV by set- top boxes and wireless keyboard.The same network is used for simultaneous transmission of TV signals andInternet data at different frequencies. A head-end unit at the cable TV networkreceives high-bandwidth data from an ISP and is transferred through cable to theuser’s home where a cable modem is attached, which in turn is connected to theEthernet card of the PC for accessing Internet through PC. To access Internet onTV, one has to connect it to a set-top box and using a wireless keyboard one cansurf the web.

Here, one can access Internet at speeds up to 40 Mbps andhigher, depending upon the service provider’s infrastructure. One can haveunlimited access to Internet at a fixed monthly rental and one need not worryabout the mounting telephone charges. The other advantage is the increasedbandwidth capacities, which is many times higher than normal leased-lineconnections. The TV mode is advantageous for first-time user and he can upgradeto the PC mode once he is familiar with Internet access.

The cost of cable modem and set-top box varies from Rs 7,000to Rs 15,000 and a monthly rental of around Rs 1,000 per month or higher,depending upon the bandwidth provided by the ISP.

Cable modem vendors are 3Com, Alcatel, Terayun, Nortel,Cabletron, Cisco, D-Link, Ericsson, Motorola, GVC, Intel, NEC, Netgame,Panasonic, Philips, Samsung, Sharp, Sony, Tainet, Teldat, Thomson, Toshiba,Zoom, and Zyxel.

DSL

An acronym for Digital Subscriber Line, it uses the existingphone line without requiring an additional line. It is a technology for bringinghigh-bandwidth applications like video-conferencing and video-on-demand to homeand small businesses over ordinary copper telephone lines. Connection speeds inDSL typically range from 1.544 Mbps to 512 Kbps downstream and around 128 Kbpsupstream.

For accessing DSL services, you have to connect a DSL modemto the DSL line of the local area network. Once connected, the DSL modemprovides you with continuous connection to the Net. In order to get better DSLservice, the end-user must be geographically within a certain distance from thetelephone exchange to avoid signal degradation.

On the technology front, ordinary telephone services use0-3,400 Hz frequency range that limits the speed to 56 Kbps on standard analogmodems. In DSL, it moves away from 3,400 Hz boundary by connecting both endsdigitally resulting in a larger availability of bandwidth following highertransfer rates.

Asymmetric Digital Subscriber Line (ADSL) is the most popularform of DSL technology and is distance-sensitive. It allows simultaneous voiceand high-speed data transmissions. High bit-rate Digital Subscriber Line (HDSL)acts as a substitute for T1/E1. Symmetric Digital Subscriber Line (SDSL) is a2-wire implementation of HDSL. It allows users to experience equal upstream anddownstream speed of up to 1.5 Mbps. Rate Adaptive Digital Subscriber Line (RADSL)is adaptive to any rate. Very High bit-rate Digital Subscriber Line (VDSL) isproposed for shorter routes.

DSL equipment manufacturers are Adtran, Advanced VideoAccess, Advanced Fibre Communications, Alcatel Bell, Amati Communications,Analog Devices, Ascom Ericsson, AT&T Microelectronics, AT&T Paradyne,Aware Inc., Broadband Technologies, Brooktree, ECI Telecom, Ericsson, Goldstar,Harris Semiconductor, IPM Datacom, Level One Communications, MetaLink, MotorolaSemiconductor, NEC, Orckit Communications, PairGain Technologies, PerformanceTelecom, SourceCom, and Westell Technologies Inc.

Satellites

They can be used for accessing Internet in two modes–one-wayor two-way. To access the Internet, the corporate user has to put up a VSAT,which comprises of an antenna and an adapter card, which is housed in thesubscriber’s PC connected to the external outdoor antenna by a cable. The usersends the request by the normal telephone line and receives the download througha satellite broadcast that is received by the VSAT and comes to the PC.

In two-way mode, both the request and the download happensthrough the satellite. It offers significant benefits for consumers, including a"always-on" connection that saves time when dialing up to the Internetand eliminates the need for a second telephone line.

Local Multipoint Distribution System (LMDS)

This is a broadband wireless point-to-multipointcommunication operating above 20 GHz (depending on country of licensing) thatcan be used to provide digital two-way voice, data, Internet, and videoservices. The technology provides a competitive opportunity to embedded wirelineor wireless networks for providing high-speed data transmission.

The LMDS network architecture consists of four parts–networkoperations centre, fibre-based infrastructure, base station, customer premise,and NOC designs. The customer-premise configurations vary from vendor to vendor.Primarily, all configurations will include outdoor mounted microwave equipmentand indoor digital equipment providing modulation, demodulation, control, andcustomer-premise interface functionality. The CPE may attach to the networkusing time-division multiple access (TDMA), frequency-division multiple access (FDMA),or code-division multiple access (CDMA) methodologies.

LMDS vendors are Cisco, Siemens, Ericsson, PCom, Alcatel,SpectraPoint, WinNet, Newbridge, Nortel, Sun Microsystems, and Airspan.

MMDS

An acronym for Multipoint Microwave Distribution Service, itis also known as Multi-point Distribution System. MMDS channels come in 6 MHzchunks and run on licensed and unlicensed channels. Each channel can reachtransfer rate as high as 27 Mbps (over unlicensed channels) and 1 Gbps (overlicensed channels).

The problem with this access technology is since it works online-of-sight concept, it does not work well in the mountainous terrain but issuitable for rural areas where copper line are unavailable.

A typical set-up of an MMDS system is a wireless system consisting ofhead-end equipment and reception equipment at each subscriber location.