Satellite technologies for Africa - a user perspective

However, there are areas of technology where this thinking doesn't apply; particularly when we are dealing with natural and limited resources, where we are forced to utilise that which is available and must still be used going forward. One such area is the field of operating frequencies for telecommunication networks. The available frequency spectrum is a finite resource and we can only improve the usage and application of available frequencies.

In the satellite industry C-band was the first frequency band that was developed; thereafter Ku-band and most recently Ka-band. These are different operating frequency bands which all form part of the finite and limited frequency resource spectrum. Although Ka-band is the most recent development, it is certainly not a replacement of Ku-band or C-band services - it is purely a "newer" technology that opens new market sectors and new user application scenarios.

In order to provide a more complete understanding between the applications for C, Ku and Ka-band satellite services we must review the origin and development of these technologies.

The origin of C-band

C-band was developed as the first commercial viable satellite communication medium. C-band systems were expensive, deployments required relative large antenna systems (4.8m to 9.3m), the electronic modem and related equipment was expensive and the applications were for specific point-to-point communication circuits.

These services were often deployed to provide international trunk circuits between US and Africa or Europe and Africa, as well as for national telecommunication infrastructure. The signal power offered by C-band services relative to the loss effect of rain and other atmospheric conditions are the most favourable for C-band systems.

C-band services have evolved and become more cost effective to deploy, although it remains the most expensive configuration. It is mostly used when reliability and service levels cannot be compromised, ie. for GSM backhaul networks, oil and gas deployments, enterprise core networks, etc.

The development of Ku-band

Ku-band was developed after C-band and its development was motivated by different factors. Firstly the increasing market demand for connectivity anywhere; anytime linked to a user requirement for more cost effective equipment and services.

In addition the frequency spectrum used for C-band systems has become increasingly congested and the industry had to develop an additional frequency band to meet the ever increasing demand. Ku-band services were introduced to supplement C-band services and to unlock new markets such as satellite broadcast networks for TV and more recently broadband networks.

Ku-band services can be deployed with much smaller antennas (1.2m for two-way systems and 60cm for receiving only); on-going development has ensured that modem equipment is more cost effective thus creating more attractive user pricing.

Today a Ku-band network offers an attractive balance between available power and atmospheric losses and Ku-band services are widely used for DTH, broadband and business connectivity networks. It must be noted that Ku-band networks did not replace the C-band networks; it actually addressed a new market need and supplement the satellite services portfolio available to service the market.

Most recent developments

Ka-band services are the most recent development in the satellite industry, and again the development of Ka-band services is driven by market demand on the application side, and frequency congestion on the technology side. By now the industry has reached a point where most available C-band and Ku-band spectrum are used and the industry has to find a new frequency band to develop.

In addition the market demand has also increased and the unsaturated consumer demand for more bandwidth, at more places and for lower prices, has driven the development of broadcasting and broadband networks to enable higher-level, more cost effective bandwidth.

Ka-band networks are thus focussed on supplementing Ku-band to alleviate frequency congestion and provide high definition TV and broadband applications. Ka-band networks are focussed on high density environments and networks must be specifically engineered to provide an acceptable balance between available signal power and losses due to adverse weather conditions.

Although this is really a preliminary discussion on C, Ku and Ka-band services and application, it does serve to provide some clarification and reference.

In summary, the key thoughts are: