We need to look afresh at how technology can bring high-quality services to all, writes Chris Bell
While fibre optic cables are today being laid around the coastline and in major African cities, there still remain vast tracks of the continent where populations are unlikely to benefit from these investments. The danger is obvious: rural areas will become more isolated and technologically impoverished.
It is with these facts in mind that we need to look afresh at how technology can be applied to overcome these obstacles and bring high-quality services to all. Satellite communication technology can provide an optimum solution to connect remote towns and rural villages with national and international telecommuni-cation networks. Regrettably, however, the widespread deployment of satellite services and technology has been hampered in some cases by bureaucracy, monopoly providers and perceived costs.
The big advantage of satellite communication is that it can be deployed anywhere and provide the full range of communication services. The direct costs of installing a satellite solution may initially appear higher than an extension of the existing public network but this may not be the total picture. For instance, the cost of installing conventional lines is often overlooked, as is the cost of maintenance and repairs in isolated areas. There is also the economic impact of being without communication while these links are restored and the old-fashioned telephone is unlikely to be reliable enough or provide the access speeds necessary to download Multimedia or e-mails with very large attachments.
Internet is the new way of communicating. Not only is it faster and easy to use, but covers the whole world and does not require the other party to be in and waiting for you to call, so time differences are not a barrier.
Until recently a dial-up connection was for most of us an acceptable way to access the Internet, particularly for sending and receiving e-mails. However, the recent growth of multimedia has made it necessary to be able to download at much higher speed.
One option to overcome problems of downloading information faster is for the Internet service provider (ISP)to subscribe to one or more caching services so that they can locally hold the data of sites that their customers frequently visit as the cost of data storage has fallen. ISPs can then make savings on the bandwidth required to access the Internet backbone. This would improve service to large numbers of subscribers.
The second approach is for an ISP to deliver Internet content directly to a customer via satellite with the return path to the ISP going via a normal telephone line. The benefit of this is that the satellite downloads data faster to the end user’s computer.
The third solution is when the return path or the uplink to the ISP is through a satellite where a wide range of uplink bandwidths can be made available. However, this is a costly route due to the need for a transmitter that is also subject to licensing costs and other regulatory restrictions.
Regrettably, the regulatory environment in many situations will prohibit individuals from transmitting or will be in the hands of a monopoly provider. If such obstacles can be overcome then the end user will still need to determine whether a permanent connection to the Internet can be cost justified.
The Internet can be likened to a global railway network with many local, regional or international operating companies whose tracks are interconnected. The question of quality of service comes into the picture as traffic congestion results from thousands of users seeking to access the Internet at the same time, thereby affecting the rate at which data can be downloaded.
At the local level there is also the question of how easily can an end user connect to an ISP via a dial-up connection. This depends on the number of modems an ISP has to handle the community of users and what data rate throughput can be achieved over the phone lines. Any or all of these may affect the user’s perception of service quality.
In the case of satellite delivered Internet service the main concern relates to the downlink of data that the user can receive. First is the size of the carrier received from the ISP a bigger carrier is not always faster. For an ISP with thousands of subscribers, the question is how to share the bandwidth among them? Does the ISP simply divide it up so that there is a maximum rate within the overall data rate that any subscriber can download at a particular time of day? The worst scenario is that of “first come first served” with the potential danger of one subscriber effectively hogging the available bandwidth.
A more sophisticated approach is where the ISP guarantees the subscriber a committed information rate on the downlink. The advantage here is that the users will always be assured of being able to download at the minimum data rate they have contracted for.
Another pertinent issue with satellite-delivered Internet is for the ISP to ensure that the satellite capacity being paid for matches the Internet backbone access speed. If this is not provided then the ISP may be paying for satellite capacity it is unable to use.
There is an increasing choice of satellites that are able to support Internet traffic. These include traditional communication satellites and those that provide direct-to-home television, which offers a range of online services such as home shopping and pay-per-view programming. Existing antennae and set-top boxes could provide additional revenue.
Satellite connection for Internet service is not simply a download at the speed of light. Other factors that need to be taken into consideration include the frequency band in which the satellite is downloading to the subscriber. Ku-band is becoming more popular because it uses a smaller receive antenna and the hardware is cheaper. However, Ku-band signals require more transmission power to overcome the absorption that the signal is subjected to by heavy rain, as opposed to the C-band with its larger and more expensive antenna. A single C-band beam can provide coverage of the whole of Africa whereas Ku-band can cover only a region. Climatic conditions and cost factors would therefore determine the optimal frequency and type of satellite technology to be used.
For corporate type networks with mixed voice, data and Internet traffic single carrier per channel solutions are ideal for a point-to-point link. Where multiple sites form a network there is scope to make operational savings by deploying sophisticated hybrid systems such as Demand Assigned Multiple Access, which are ideal for specific applications such as distance learning and tele-medicine.
An alternative is a point-to-multipoint system where the transmission of each site is received by all other sites in the network. For isolated communities, farms and lodges an on-demand solution is ideal on a pay-as-you-go basis.
Reliable access to the Internet backbone is essential. Where an ISP is operating in multiple locations within a country or continent, a point-to-multipoint solution will serve well as traffic to the locations can be delivered on a single carrier with the local router then throwing away irrelevant packets. In the return (uplink) direction each location will transmit their own carrier thereby ensuring that all the ISPs are continually online for their local customer.
For customers there is a range of technical platforms that can be adapted by various service providers. Many new receivers use digital TV technology that incorporates a telephone modem, which enables the users to send e-mails and Web requests over a phone line while receiving the download at a higher rate over the satellite. The increasing widespread availability of these desktop satellite Internet receivers is enabling even those in remote areas to benefit from a high speed Internet connection at a realistic price.
Liberalisation to allow the entry of many service providers on to the market would bode well for making Internet access affordable. So is the imposition of reasonable duties on equipment and the licensing of services. Improved access to a reliable electricity supply, a dire need in many rural areas, is also essential for connecting to the global Internet information highway.
Chris Bell is MD for Redwing Satellite Solutions, United Kingdom. This is an abridged version of a paper presented at the African Computing and Telecommunications Summit in Pretoria on August 1