Recent advances in digital radio and digital signal processing that form the basis of cellular and satellite communication have reached a degree of maturity. The basic, core components are now available as low cost VLSI chips. These can be used to develop low cost networking solutions. In my paper, I will describe our experience in implementing an electronic mail service that is in operation for the past several years providing good Internet and other international connectivity at 9.6 Kbps and 64 Kbps. To start with, the land lines were not able to support 9.6 Kbps over a distance of even a few Kms! To overcome this an inexpensive digital UHF transceiver was rigged up. This provided good 9.6 Kbps duplex connection for several years between the local host and the international gateway switch which provided a dedicated line to the Bitnet node in Geneva (CERN). More recently this has been upgraded to 64 Kbps (via the new improved land lines) providing excellent connectivity to the strong academic community with international connection and collaboration. Another network, the Ernet, has been established a few years ago with special initiative from the Department of Electronics. This is serving a large number of R and D and academic workers throughout India. However, its expansion plan has run into problems with the telecom monopoly, the Department of Telecommunications.
Cost of several advanced technologies have dropped to such a level that they can be considered for low cost digital wireless solutions. RF modules in GHz band using gallium arsenide devices have opened up entirely new possibilities. Digital Signalling Processing provides a means of overcoming the limitations of imposed by noisy media and narrow bandwidths. Spread spectrum techniques have entered into the cordless telephone. A remote VSAT station with local distribution based on CDMA or TDMA techniques will be able to interconnect the remotest locations in the developing countries. India has planned a satellite (VSAT) based network, INFLIBNET, for interconnecting University Libraries across the country. Each station will be connected to a LAN. This network can be easily adapted and expanded for Internet connectivity to all the Universities.
There are several areas where the only connection with the outside world is through telex. It provides a reasonably reliable service at relatively lower cost. Until such time as the PSTN improves, such areas can be brought into the e-mail network (with some limitation) by having Baudot - ASCII interface at a host. This would be extremely helpful to some of the isolated R and D centres in the remote areas of poor countries. They can also access the nodes at centres such as the International Centre for Theoretical Physics at Trieste that are assisting the developing countries.
Future trends indicate two clear directions. The establishment of satellite based services such as the world wide personal communication services using low earth orbiting satellite LEOs and paging and, the closer integration of the computer, the telephone and the wireless technology. These trends indicate new possibilities of achieving cost effective Internet networking in the developing countries. As a result of the globalization of economy, the business and the industry there is a strong urge for Internet connectivity. This would help in improving the economic viability of this facility.
Based on our experience over the past ten years, I will describe in detail a few selected networking solutions based on digital radio using the state-of-the-art techniques and indicate a few directions for the future.