Much has been said about the Ku v Ka band, but as we pivot to High Throughput Satellites (HTS), let’s consider how frequency will impact the ecosystem.
First we had the Ka revolution, where the VSAT industry entered a new era of satellite communications, dedicated to delivering data services. Then there was the battle of the bands where the VSAT community debated if it really was a Ka play, or could the same architecture be delivered with KU.
NSR coined the term “HTS” to encompass this model, whether with KU or Ka, but which band do you think is better suited to HTS?
Satellite services are delivered on a range of spectrum as shown in the diagram below. I have tried to give a rough idea of the impact that the frequency band has on a variety of characteristics. So in general usually a L band based service would have lower throughput than a C Band. Ka band on the other hand has potential to offer much higher speeds. This is mainly due to the amount of spectrum available. It is always surprising to me, just how little spectrum is allocated to L Band. It requires much less spectrum than Ka, so if you look at the services provided here they are providing much less aggregate throughout at the IP layer regardless of the technology used.
Typically, the amount of capacity that is allocated to these L Band satellites is less than 40 MHz. Now compare that to the Ka end of the chart and you will see frequencies of more than 3GHz allocated to the use of FSS and BSS. Clearly, there is a lot of opportunity to deliver higher throughput services from Ka satellites.
What else can satellite operators do to best utilize spectrum?
Let’s consider how spot beam technology helps. It certainly gives the satellite operator some further advantages. The link budgets improve as the beam size reduces, resulting in higher Bit/Hz utilization of that spectrum. So these throughputs will increase, in general as the frequency goes up. The small spot beam also allows for frequency to be reused multiple times, at higher frequency. Satellite payload antennas can be made that are more accurate in terms of beam width, and thus the spots can be smaller.
Frequency reuse can be used by Ka HTS satellite operator or in Ku as well, as in the case of Telesat KU.
In the next piece of this blog, we’ll discuss antenna size.