Ku vs Ka: Battle of the Bands

Denis SutherlandBy Denis Sutherland, Sr. Manager, Sales System Engineering 

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?

Do you want to know the answer? … it depends on a few factors, but new entrants without access to Ku spectrum will more than likely look to Ka. Incumbent satellite operators with vested interest in Ku will likely use the spectrum they have. L and C will not be going away, but it’s unlikely they will be used in a HTS model, let’s consider why.

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.

image1

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.

32 Responses to Ku vs Ka: Battle of the Bands

  1. Tom Cox says:

    Denis,

    This is a good article and a great way to start a discussion about HTS and frequency bands. In my mind, the greatest benefit of Ka-band is the ability to deliver very narrow beams of extremely power bandwidth of 1GHz or more. A Ka-band spot beam can be far narrower than Ku-band spot beam, which means satellite operators can reuse that frequency band hundreds of times. Viasat-2 is expected to supply more than 400 GBPS of throughout on one satellite.

    This isn’t trying to beat up on ‘legacy frequency bands’ – remember when Ku-band supplanted C-Band as the workhorse for SATCOM back in the mid 1980s? And HTS technology has its place in Ku-Band because of the lower impact from weather-related issues. I’m excited to see some new and innovative business models involving Ku-band HTS.

    Let’s keep the conversation going and make sure we don’t confuse end users with spin designed to protect legacy investments in the name of innovation and growth, which accurately describes some of the other HTS ‘white papers’ I’ve read around the Internet lately.

    • @Tom

      Thanks for the nice comments, and it’s great to get your view on this. I like the additional talking point you raise. Would it be true to say you could achieve around a beamwidth of 2Degrees with Ka and 3 with KU, does not sound a lot but I guess it has a big impact in terms of size of beams. I certainly agree it is in everybody in satellite industry interest not to confuse the end users, and try and present an honest open discussion. Obviously you also started there are some interesting new KU HTS satellites in the pipe along with high profile KA. Exciting times for the industry.

  2. Lindsay Cumberbatch says:

    Since 2002 when uk operators started to take broadband service via satellite seriously there was certainly a shortage of good throughput via ku. The relatively recent availability of ka in the uk has certainly opened the door for integrators and suppliers with uk based operators missing their obvious advantages over non uk based operators. I have delivered both types of service over iDirect, and despite the rain fade question, I have personally experienced no ka outage at all in the uk with our chosen operator. The mitigation really seems to works. The issue with ka I find is the operators charging model for switching beams and the type of terminal available to cover beam switching. Ku simply fits better for the RV, travelling client especially where cost, as most of this type of client will attest, is the limiting factor.

    • @Lindsay
      Good to hear from you. I know you are an expert at providing satellite communications in mission critical environments, so it great to hear you view. I think you raise a very good point about the base of operations, and I have written a future Blog about HTS feeder links and how these can influence the location of the earth station. Obviously for many of your government customers it is important to understand where the data lands and the locations of earth stations. It will be interesting to see if Ka will compete for Ku business in the RV sector in the future?

  3. Emil Samarah says:

    Deat all,

    I believe it is not only a matter of frequency and the amount if throuput, but the network architicture too. I found it really challenging to obtain an operational/service provider license in country A, with a gateway in B.

    Many counties are demanding an in country hub for obvious reasons.

    From a customer view, I guess it’s a matter of convenient and price, I tend to agree that KU is more mature when it comes to terminals availability especially mobile units, applications and customer experience.

    Many applications corporates and governments need more than DSL like services.

    • @Emil

      Thanks for your perspective. The location of the gateway is critical in some cases and will impact a number of factors, including licencing. HTS feeder beams or link will also mean that some Teleport operators will not be able contribute towards the satellite, or may gain more business as a result. Its an interesting talking, and one which I will post Blog on.

      I am not sure what exactly you mean by the government and corporate customers need DSL like services? is that in terms of speed, contention, SLA ?

      • Emil says:

        Denis,

        I meant not only for broadband connectivity, but point to point and point to multi points. A ku architicture with ka band freq might fe the best combination

        • @Emil – Very true, for example your terminals side frequency need not be the same as your feeder link to the satellite for example, that is a good point. I talk about these feeder links in a future Blog.

  4. @Peter – Thanks.

  5. Eric says:

    As a government of Satellite Bandwidth both for routine and disaster communications, I like the idea of the cellular approach to satellite bandwidth. The throughput of services such as VIASAT are truly amazing but priced outside of what most governments can afford. Our 1.2M C-COM Auto-Deploy Antennas were a huge investment but, already we are starting to hit the threshold of reliable bandwidth, is this due to design limitations of the equipment whether it is the bird or the antenna? New equipment is costly and as a government user we typically purchase hardware revisions with grant funds, that revenue stream has been dropping considerably over the last few years. I would like to see small cell areas of coverage, tremendous bandwidth in the neighbor hood of 25-50 Mbps Up/Down symetrical, in a package that is easily deployed and does not require more space than that of a 1.2M dish.

    Additionally, satellite providers need to offer pricing of service that is reasonable, for instance don’t limit to the number of days and then give unlimited bandwidth, or unlimited days and a finite amount of bandwidth.

    For government users where the systems are often not even turned on for months at a time, we need an unlimited number of days, bandwidth, and quantity. It is far easier to budget for a set cost then to budget for something that can move around at a moments notice.

    • Robey Larsen says:

      Eric, Have you considered the Inmarsat GX platform

      Global Ka band service supporting terminals from 65cm

      Service has very small spot beams and therefore tons of power to support data rates of 50Mbps

      Service has been designed for both Governments and Militaries and well suited for your type of requirement

  6. Neil Mackay says:

    Denis, it is encouraging that your posts stay away from the hype. Many thanks. As you may know, I am mostly interested in the agile mobility sector whose requirements may turn out to be band-specific. I’m looking forward to your antenna posting as that may well be one of the most critical elements for us mobile folks. Best…

  7. @Neil

    Many thanks, I do try to offer a balanced view, so its nice to be get some positive feedback from yourself. The mobility sector definitely the most interesting, with all band been offered to the customers in some kind of service. So it will be interesting to see how it works out in the long term. The antenna post is up.

    http://blog.idirect.net/antenna-size-does-it-matter/

  8. @Eric You probably know that their a few satellite up their that take a different approach to HTS. And rather than having a continue coverage of multiple spots like the Viasat-1, they have a smaller number of more focused beams, some people call this the Hi-Cap model. WGS and Athena do this for military users.

    A slightly dated but good paper on it from a UK / airbusperspective

    http://www.satcom-airbusds.com/wp-content/uploads/2014/04/a-review-of-the-two-primary-types-of-ka-satellite-systems.pdf

  9. Velumani says:

    Hi Dennis,

    It was great to see and read the article of yours a well balanced view.

    For back hauling of links for a large mobile network will the Ka HTS be ideally suited and if so what kind of latencies it can offer for 4G/ LTE users.

    Regards

  10. John Brundle says:

    Been out of circulation for a while now but from an end-users perspective, is site licensing visits an issue? In the early days, Ku site licences were expensive but after extensive negotiations, costs were brought down but don’t know what the charges are for Ka sites. Are these now reasonable and controlled in the same was Ku sites are registered?

  11. Denis Sutherland says:

    Velumani,

    Thanks for the nice words. Both Ka and KU are used for backing 4G /LTE currently, and could be used with HTS too. If you would like to send me a direct mail I can ask somebody to send you some more details and discuss any requirements you have.

    All the best,

    Denis

  12. Denis Sutherland says:

    John,

    Good to hear from you! Hope you are doing well.
    You pose a good question, and one I think you know more about that I do. I am not sure how the costs would compare worldwide, but are they not free now in the UK?

    Denis

  13. Denis,

    KA is the future for specific services, no doubt. Thank you for starting this discussion.
    However, there are a few issues to resolve IMHO. Notably homologation of the RF equipment and the legal framework for using this spectrum. Some regulators seem to be running hopelessly behind the developents.

    Also, maritime roaming and antenna approvals (by the satellit operators) seem to be an issue in certain regio’s all be it one may expact these challenges to be tackeled over time.

    The possibly reduced antenna sizes(compared to C and KU and) resulting from the higher spot beam EIRP’s and the physical characteristics of the higher frequencies I think are helping for widely acceptance by the target audience ($$, lesser visual intrusive etc).

    Best,

    Ton Klompmaker

  14. Kemi says:

    How does 2Ku compare to Ka HTS?

  15. Denis says:

    Kemi,

    Not sure I am in a position to comment on 2KU which is a service versus Ka in general.
    Individual service providers will make lots of different choices, and selection of the frequency band is only one part of a solution. The other aspects such hardware and software selection, design of networks, and RF will all have an impact. Some would say Ku and Ka have there pro’s and con’s but really success will be determined by how networks are implemented.

    All the best

  16. Yajan Dua says:

    Hello Denis,

    Considering the battle of bands and global investment on satellites (LEO, MEO & GEO) to be $179 billion in 2014, which band would attribute the most and the least and by how much?
    Taking into account the success of Ka band followed by Ku and C band, how the scenario will shape up for the teleport operators?
    How the investment would change among the band tomorrow as compared today??

  17. Denis says:

    Yajan,

    Good question, I am not sure I the best placed to answer all of these.
    The satellite industry has historically had a lot of investment in GEO Ku, but yes we have seen LEO and MEO constellations announced, what will the result be going forward is the question everybody in the satellite industry is asking.

    Investment in Ka, away from Ku and C ramped up over the last few years, but the answer really depends on the markets you are interested in. Video DTH is still mainly Ku, where a lot of consumer HTS are Ka but that is really driven by access to spectrum. We have seen Inmarsat and Telenor use Ka for Mobility platforms, and SES and Intelsat use Ku.

    Check this report from NS out for more info

    http://www.nsr.com/upload/research_reports/NSR_GASSD9_Brief.pdf

    So to answer you question, the biggest increases in investment is probably going to be in Ka, just because many new entrants will need to use that spectrum, as Ku is more scarce. But the big picture is that a lot of investment is been considered across all bands, and all orbits. Satellite is on the rise, and going mainstream.

  18. Rahul says:

    Although Ka and higher bands are attractive from the point of view of the amount of frequency
    bandwidth that the satellite can potentially use, there are limitation that could dampen the enthusiasm of using them if specific techniques were not implemented in the satellite system to guarantee the capacity and the availability and the quality of service.

    According to my rough estimation:
    – C band (4/6 GHz) FSS (fixed satellite services) – 10% of the market
    – Ku band (11/14 GHz) FSS (fixed satellite service) – 20% of the market
    – Ka band (20/30 GHz) with satellite on board processing – 40% of the market
    – L band (1.5/1.6 GHz) MSS (mobile satellite service) – 25% of the market
    -X Band – 5% of the market

    Any comments ??

    • Denis says:

      Rahul,

      I have not analysied the market in such a way, so could only give you feel for it.

      But what “market” do you refer to, and what do you mean by XX% of the Market?

      I am presuming we are talking VSAT and not satellite in general?

      and in terms of your share of the market, do you mean:
      -Number of terminals
      -Revenues
      -Amount of Equivalent transponders of capacity?
      -satellites in orbit?

      But by most measures Ku is more prevalent currently than the other bands.

  19. Yajan Dua says:

    Hello,

    As per my study,
    Intelsat has a fleet of 50+ satellites and eight owned teleports;

    Eutelsat has a fleet of 34 geostationary satellites and more than three teleports;

    SES, which forms the worlds’ leading HD platform has a fleet of 50+ geostationary satellites, 9 owned teleports and 9 third party partner teleport;

    Telesat has a fleet of 13 owned and 2 third party partner teleport;

    Apart form this, SES is investing into new satellites, expecting launch of seven new satellites by the end of 2017.

    My area of concern is how many earth stations will be required to track the projected number of satellites to be launched??

    • Denis says:

      You are quoting a mixtures or FSS and BSS, but you miss a whole MSS segment.
      Also you dont mention satellite operators like Inmarsat, or even Viasat who have smaller numbers of satellites, but large number terminals. iDirect service the Enterprise markers, where customers demand high technology solution for Maritime, AERO, Defence, Cellular, Telco, O&G where the numbers of terminals are less important and value of service provision is.

      Therefore I recommend you contact somebody like:

      http://www.nsr.com/
      http://www.comsys.co.uk/
      http://www.euroconsult-ec.com/

      They have much better understand of numbers of terminals in the market.

      Or maybe ask you question in a different way, and I will be try to help, why do you ask?

      Hope that helps

  20. Johnson says:

    Hi Denis!
    I would like to know “ka band” service in equatorial area.
    1. Have this “ka band” services functioned well in equatorial area now ?
    2. What space segment (satellite) and ground segment (hub and remote) that have been used a lot all over the world?
    3. Is there a new technology for HTS that will implemented soon?
    Thanks for helping.
    Johnson B.
    http://www..satkomindo.com

  21. Eric says:

    Denis,

    Do you think it would ever be practical for TSPs that use the community aggregator model for voice communications in remote regions to use HTS Ka band? Can onboard-processing deal with the latency issues that stem from the double hop? Or will attenuation from weather mitigate the usefulness of Ka band for voice?

    • Denis says:

      Eric,

      Thanks for the question. I dont see the two thing as related. Onboard switching can be in Ka Ku or X in the case of some military satellites. Double hop can work in some situations, yes its a lot of latency but I know from personal experience that it can be acceptable. I deployed double hop voice systems in the 90s for the military, and we used it no problem. I guess it comes down to expectations of quality, and latency, not sure what your customers are used to and if they have alternatives.

      Ka can be used in all weathers, its just a design problem. Factor in link budgets, satellite capability and use of mitigation techniques such as DVB-S2 ACM and Adaptive TDMA.

      Denis