NICNET is a VSAT based network. All the metropolitan cities, State capitals and important towns are connected to NICNET through high speed VSAT backbone. In each of these locations, NIC computer centres and NICNET users are located at scattered places. NICNET connectivity is extended to these NIC Centres and Users from the place where VSAT Backbone terminates using various technologies available for local access.
Till recently, local access was being provided only through Dialup, Leased lines and ISDN available from DOT/MTNL. Depending on the line quality, Dialup connection can work from 1200 bps to 28.8 kbps. This kind of connectivity may be good for individual users but it is not suitable for connecting large user groups. To ensure higher speed and better line quality, ISDN is now available in many cities. For applications which require constant access to the network, leased lines of various speeds are being used. Leased lines are expensive and may not be available at all the places. Moreover, it takes a considerable amount of time to get a leased line.
With advancements in the field of Information Technology, many new applications have come up, which essentially require high speed and reliable network connectivity. The quality of network services significantly depends on the quality of local access. It is with this view of providing high quality, high speed local access to its users that NIC decided to use 'Hub based Spread Spectrum Wireless Access Networks'.
The Technology NIC's wireless data networks are Hub based. Hub being a central point for communication, all communications are directed through the Hub. These Hubs are located at NIC offices where they are connected to NICNET through a high speed port. Each Hub capacity is 2 Mbps which is shared by all the users (Remotes) communicating with it over wireless medium. By limiting the number of Remotes and by studying traffic patterns, it is possible to ensure high speed connectivity.
The Remote Equipment of the wireless data network has to be installed at the remote end at user premises. The Remote Equipment and Hub communicate over wireless medium at all the time ensuring constant link availability.
The Hub based wireless data network uses Spread Spectrum (Direct Sequence) wireless technology and operates in 2400 MHz to 2483.5 MHz frequency range. The technology is highly interference resistant which ensures availability of robust wireless link all the time and provides high level of security. In addition to the security provided by Spread Spectrum technology, availability of Network ID and Encryption makes the wireless link highly secured.
The Link Feasibility To make a wireless link operational, direct line of sight between Hub and Remote antenna is required. If there is no direct line of sight available, possibility of making a link operational through a suitably located wireless Repeater is explored. The Link may not be feasible for a variety of reasons, such as :- The aerial distance from Hub being more than 12 Km Non-availability of a suitable repeater location Terrain may be difficult not allowing radio signal to reach Remote Location of Remote equipment in a building which may require too long a RF Cable Not getting permission for installation of a mast of required height for antenna In such cases, alternative technologies like VSAT and Leased lines may have to be explored.
The Remote Equipment The term "Remote Equipment" refers to the equipment installed at the user premises and connected to users' LAN or computer. To suite the requirements of various users, two types of Remote Equipments are offered viz. Type-1 and Type-2.
Remote Equipment (Type-1) is a stand-alone equipment consisting of Radio Interface, LAN Interface and Power Supply. The Radio Interface is for connecting RF cable from antenna. LAN Interface is for connecting wired Ethernet LAN. The equipments works as a Bridge which filters out local traffic and forwards only packets meant for going outside the user's Intranet.
Remote Equipment (Type-2) is in the form of a PC/AT, ISA Card which can be installed in any computer of PC architecture and having ISA bus slot. The Type-2 equipment is not a stand-alone equipment and requires a computer for its operation. The equipment has a Radio Interface for connecting RF Cable from Antenna. Drivers for all the popular Operating Systems and Network Operating Systems are supplied along with the Equipment. By installing a Type-2 Equipment in a PC with appropriate Driver, the PC can have wireless access to NICNET and Internet. It is also possible for all the users of wired LAN to have simultaneous access to NICNET and Internet using Type-2 Equipment. For this, Type-2 Equipment may be installed in the Server running Network Operating System with appropriate driver software and Server may be configured to route all packets for NICNET and Internet to the IP Address of Type-2 Equipment. It is also possible to create a gateway for NICNET and Internet for wired LAN by installing the Type-2 Equipment with appropriate drivers in a PC which already has a Ethernet card connected to LAN. The PC can then run a routing software or Proxy Server.
The Installations So far NIC has installed Hub based Wireless Access Networks at Delhi, Hyderabad, Bangalore, Agartala and Warana Nagar providing NICNET and Internet access to seventy remote locations. These Remote locations have LANs with large number of nodes. Installations are in progress at Lucknow, Chandigarh, Jaipur and Shillong. In Delhi, almost all the major NIC computer centres located in different buildings are now connected by wireless links. There are many NIC computer Centres in each of these building sharing one wireless link. In such cases, wireless access network provides an effective and low cost local access solution.
The Advantages ● The access speed of NIC's hub-based wireless access network is faster as compared to various other technologies in use. ● The cost involved is much lower than the cost of VSAT and Leased Line access of comparable performance. ● Lower costs also lead to lower annual maintenance charges. ● There are no associated recurring charges for using the transmission medium. ● The equipment directly gets connected to LAN or PC and does not require expensive internetworking equipments. ● Implementation can be done quickly in days and weeks as against waiting time of months to years for leased lines. ● Uptime of wireless network is much better than leased lines and any breakdown can be quickly fixed as the network is under NIC's administrative control. ● All the clearances and approvals for operation of a wireless network are taken by NIC. Users are not required to take any clearances and approvals.
The cost of providing a wireless link is solely dependent on various equipments used to make the link operational which is in turn dependent on the location of the site with respect to Hub location. Thus the cost factor may be different for different sites.
The Future Plans It is planned to install Hub based Wireless Access Networks in all the State Capitals and important towns. This will provide most of the NIC users a high speed local access. Cities where Hubs are operational have more requirement for the Wireless Remotes. By adding more Remotes and by installing more Hubs in these cities, the Wireless Access Network will become a high speed Metropolitan Area Network.
NIC also plans to use the wireless equipment for providing point to point connection between two buildings where it is difficult to put wires. Wireless solutions are also to be used for in-building LAN in 'difficult to wire' buildings where roaming is a requirement for quick and temporary LANs.
Requirement for higher data rates is already being felt for which plans are there to use Laser Links which can give data rates from 20Mbps to 155Mbps and high speed wireless links on heavy data traffic routes. As this technology area is fast evolving, NIC plans to use the latest technology for providing cost effective solutions.