Satellite technologies for Africa - a user perspective

Dr Dawie de Wet, CEO at QKON.

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In today's ever-developing technology environment, characterised by the daily introduction of new technologies and services, users have become accustomed to continued upgrade and replacement programs. The iPhone 5 replaced the iPhone 4 and Windows 8 replaced Windows 7 (or maybe not quite). The general expectation is that anything new today is an improvement on what was there before.

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, says Dr Dawie de Wet, CEO at QKON.

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.

C-band was developed as the first commercial viable satellite communication medium. C-band systems were expensive, deployments, required relatively 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.

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); ongoing 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 supplements the satellite services portfolio available to service the market.

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 focused on supplementing Ku-band to alleviate frequency congestion and provide high-definition TV and broadband applications. Ka-band networks are focused 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:
1. What is new doesn't always replace what was there before.
2. Development of new technologies opens new markets, doesn't always replace previous markets.
3. The correlation between technology and application is of more importance than selecting the latest available technology purely on the basis that it is better because it is new.

Table 1: User Guide & Quick Reference