Overview

Communications satellites can provide high-speed Internet access to virtually any location in the world and service offerings to residences and businesses are readily available.  In recent years, it has become more common for rural and remote communities that have no other access to high-speed Internet services to establish local community networks using satellite for backhaul and wireless systems for local distribution.
 

Satellite broadband services involve an asymmetrical transfer of high-speed data between the Internet and the user at upstream speeds that usually range between 50 – 256 kbps and downstream speeds between 400 – 500 kbps with bursts up to 1.5 Mbps. The earlier versions of these residential and business services, such as Hughes DirecPC, were one-way.  It involved a combination of dial-up access for the upstream transmission and satellite for the downstream, transmitting data to a computer via a satellite dish installed at the customer’s premises.
 

The newer generation of satellite delivered high-speed Internet service is a two-way service, where the user connects to the Internet using a single satellite dish installed on the customer’s premises that both receives and transmits data directly between the satellite and the subscriber’s computer.  This routing of data is all controlled through satellite company Network Operations Centre (NOC).  This two-way service for residential and small business users is widely available and is provided by many satellite operators.  Business offerings will often provide a download speed of up to 1 or 2 Mbps, but at greater prices than the basic residential package.
 

Advantages and Limitations

What are the capabilities and advantages of using satellite technologies?

• The major advantage of satellite high-speed Internet service is that it is available to virtually any location in the world and it is often the only alternative in rural and remote areas.

What are the constraints and disadvantages of using satellite technologies?

• There is an inherent latency in data transmission of about a half-second because of the data travel time between earth and the geostationary satellite, which is located a distance in space of 35,786 km (22,240 miles) above the equator.  Additional latency can also be introduced by transponders and gateways increasing delays by a factor of two or three times.  A number of applications are sensitive to these delays, such as interactive gaming and it does not support voice over IP.
• Transmission speeds are not normally guaranteed and can be subject to considerable variations dependent on factors related to shared bandwidth and fair access policy.
• The monthly cost of satellite services is generally more expensive than other technologies, such as DSL and cable modem, and the equipment and installation costs are significantly higher.
• Inclement weather may cause transmission problems and service delivery issues.
  

Satellite Technology and Local Open Access Networks

An increasing application for communications satellites is to use them in conjunction with wireless for the provision of community-wide high-speed Internet networks in rural and more particularly in remote communities.  These community networks are often established by voluntary groups or by companies that specialise in building and operating them on a commercial basis.  In both cases, service provision is dependent on all users paying an ongoing fee to subscribe to the service.  The speed of the Internet connection made available to each subscriber is dependent on the backhaul capacity provided by the satellite service provider and the contention ratio (i.e. number of subscribers sharing that bandwidth).  The service offering is typically 512 kbps downstream and 128 kbps upstream.
 

Although these community networks do provide a valuable service to the community, the use of satellite technology does not represent an ideal platform for the development of local open access networks. The price of the satellite backhaul is significant and represents a major constraint to the bandwidth that can be provided.  These networks can provide a basic level of service, but they will always be constrained by the price of satellite backhaul, which in turn is dictated by the capital and operating costs of the satellite.  These community networks are generally small and do not lend themselves to the provision of services by multiple providers.

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