Ground Segment: Transformational Antennas II – Will terminals realise the promised LEO Connectivity Revolution?
Thursday, 13 August 2020
3:00 pm UK time / 10:00 am US Eastern time
Part 2 of the GVF Webinar Series focus on ‘Transformational Antennas’ followed on from the Part 1 consideration of the question “End of the Parabolic Paradigm?”, and produced another energised dialogue that took the conversation on the LEO connectivity revolution into 15 minutes of extra-time.
An indication of the well-focused nature of the 75-minute analysis came in one of the panellists’ closing remarks. It was noted that discussion about achieving elevated connectivity gains for more markets and more users around the world so often only focuses on advances in the space segment, on the satellites launched to orbit, whereas it needs to be more fully acknowledged that the achievement of those gains is dependent on critical changes in equipment on the ground. A better balance needs to be brought to open and public discussion – and that was the view from a representative of the space segment!
Augmenting questions from the moderator, the audience located in 74 countries, used the webinar platform’s real-time Q&A function to put more than 20 questions to the panellists’. Not all could be addressed, even with extra-time, and those remaining unanswered will be responded to by the panel for publication on these website – Webinar Series – pages, along with the video recording of the event.
This was the first public platform taken by OneWeb since its post-Chapter 11 acquisition by an investment consortium of the United Kingdom Government, Bharti Global, and Hughes, and the dialogue revealed important details of OneWeb’s evolving business plan, its intended launch schedule for the remainder of 2020, and its ambitious timeline to start of service delivery.
Underlying discussion of the various antenna types – parabolic technology, through to “flat panel” (FPAs) passive and active phased arrays, electronic steering technology, and optical beam forming – were really some basic questions.
Given that FPAs have been around for some time, in few numbers, serving high-end applications where the prime consideration is performance over cost, when will we see the technology, which, though it is fully understood, continues to be slow in jumping to manufacturing economies of scale that will bring to market a US$500 terminal that will capture the realities of consumer pricing requirements. The dialogue was positive that this jump could be made now, but it requires a push, or a catalyst, to break a current chicken-egg-chicken dilemma.
A related basic question asked what the absence of mass produced terminals will mean for LEO constellations like OneWeb, for which serving the antenna price sensitive consumer is a central tenet of the business plan. It was suggested that such different factors as community wifi/ small cells, and government support in the form of universal access subsidies may need, at least initially, to come into play.
In one part of the dialogue thoughts turned to the really fundamental issue – that there are really only two key reasons to turn to an FPA technology to replace the very high efficiencies of parabolics. We won’t spoil it here to reveal those reasons… Watch the video recording here. In common with those of the “live” webinar audience who posted comments at the end of the discussion, you’ll find it a 75-minutes well spent.
Q & A continued….
The following questions were posed during the webinar but there was insufficient time to respond during the one-hour duration of the event. Thank you to our audience for taking an active part by asking questions, and to our panellists for their time to answer them after the webinar ended…
1. For OneWeb, in easy terms, OneWeb has to generate >US$1M/day in NET NEW BUSINESS to close the business case, every day for the first five years of operation. How does your business plan support this rate of growth in a market that will soon have five (or more) LEO players?
Michele Franci: The demand for data continues to rise exponentially and in these times of COVID we’ve seen existing infrastructure placed under unprecedented strain and exposing critical gaps. Almost half the population remains unconnected. This is a major problem and we are focused on doing all we can to help bridge the gap – the need for better connectivity is clearer than ever. Our system advantages enable us to provide a valuable offering to a range of markets including Maritime, Aviation, Government, Teleco operators and more. With seamless connectivity, we can deliver uninterrupted experiences and reach remote and rural areas that have previously been without connectivity. In other terms, the underlying market needs appear to be strong and we do not believe it will not support OneWeb’s business plan once we are operational. With respect to the possible LEO competition, despite the possible financial backing other projects may have, we believe the regulatory constraints and intrinsic spectrum limitations will not allow more than two or three LEO constellations to become operational.
2. What’s OneWeb goal for maritime? When will it be available?
Michele Franci:OneWeb is powering the digital transformation of vessels at sea. We’ll provide networking solutions tailored to any need, at any level, replacing one-size-fits-all connectivity with a full spectrum of tailored, customisable broadband channels. Our high throughput, low-latency global network can deliver unique flexibility, lowering the barriers to high quality maritime connectivity, minimising environmental impact, and enabling the fleets of the future. A well-connected ship is the starting point for digital transformation. Fibre-like connectivity at sea is a fundamental enabler for cloud solutions and transformative technologies such as Industrial IoT and automation. Better cargo tracking, security and systems for predictive maintenance will deliver significant efficiency gains. OneWeb’s goals are greater than pure connectivity, and we have a role to play in delivering these transformative solutions. In terms of timeline, we were already well advanced in developing the maritime products and expect to start deploying them from 2022.
3. OneWeb has been described (by its key salespeople) as a little bit faster, lower latency, and a little less expensive that Inmarsat’s Global Express… Does that really drive customer adoption?
Michele Franci:OneWeb’s connectivity is a high throughput, resilient, low-latency innovation in broadband communications. It will feel like fibre (fast, near-real-time and seamless). Today very few applications truly sensitive to low latency use satcom links. However, the telecom world is more and more providing individual or enterprise users cloud-based applications that depend on low latency. Once OneWeb will be in service, we expect the rate of adoption to be very significant as user communities realise how much of the applications and use cases that would not be supported by traditional satcom systems are now in reach in areas and situation in which terrestrial is not an option. Our customers seek resilience, freedom, and sustainable growth. We use all our engineering ingenuity to solve tricky problems for our customers such as providing affordable, low power, easy to manufacture, install and use tech. Our customers want to buy something that lives up to its promises: that works, is safe and sustainable. We can give them what they want, in the way the want it.
4. What happened to OneWeb’s/Greg Wyler’s US$15 antenna? Marketing stunt?
Michele Franci: Greg Wyler’s comments referred to an independent company active in developing passive electronically steered antenna solutions, not a OneWeb project. We suggest referring the question directly to Greg.
5. Active arrays are very expensive and power hungry due to the active phase shifter chips but there are some ideas to use passive phase shifters that could made it cheaper and use less power. Why are these technologies not explored or implemented?
Michele Franci: Passive phase shifters carry indeed very strong potential of lowering the antenna BOM cost. Several companies are very busy developing solutions based on such technological choices, albeit, with quite different designs, like Kymeta, Alcan, Wafer, Isotropic, etc. Passive-based solutions however carry an intrinsic performance deficit which makes them naturally bigger than an equivalent active ESA based solution, and despite the elegance and interest of the designs proposed, several companies have to date hit important issues to productise these designs and achieve an affordable manufacturability.
Brian Billman: Actually, you can think of Isotropic’s optical beamformers like passive phase shifters. Or more accurately, passive time delay units since they do not introduce beam squint. This not only simplifies our circuitry and reduces costs, but also drastically reduces the amount of active circuitry per beam which lowers power consumption. The challenge for other technology is that most transmission line or PCB/IC based passive phase shifters are very lossy which ends up having a big impact on the terminal performance because they must go in front of the amplifiers. With Isotropic’s technology however, the combination of our unique design approach, custom low loss material, and lack of resonant structures ensures that there is almost no impact to the signal in front of the amplifier while still maintaining the benefits of passive time delay.
Bill Milroy: A useful figure-of-merit for the efficiency of ANY antenna (parabolic or FPA) is the sum of its LNA NF plus Front-End (pre-LNA) Losses (spillover + blockage + OMT + diplexer for a parabolic… radiator + dielectric(s) + phase-shifter(s) + N-way feed for an FPA.) State-of-the-art today is of the order of 0.8 dB NF + 0.7 dB for Ku-band (12 GHz) antennas and 1.3 dB NF + 0.9 dB for K-band (20 GHz) antennas. For every 1 dB increase (in F/E loss and/or NF) above these baseline values, the G/T of the system drops by 2 to 2.5 dB/K! So, if a given (lower-cost, lower-power) “passive” FPA has an additional 2 dB of added phase-shifter and/or dielectric/feed loss as compared to another FPA, one can expect a 4 to 5 dB/K net penalty/reduction in G/T (efficiency!)
Ralph Brooker: They are! ThinKom, Kymeta, Alcan, and others make flat “passive” array antennas with electronic or electromechanical pointing. These antennas use conventional external LNBs and BUCs.
6. What are the expected percentages of availability for LEO satellites and at what plane and what fleet density? Can they get anywhere near the 99.999999-100% availability of GEO?
Michele Franci:GEO-based connectivity networks do not have the availability hinted in the question, far from it. End-to-end network availability for a not redunded GEO network is around 99.7-99.8%, when using the standard end user performance sampling attached to most service level agreements. LEO constellations, properly designed, can have comparable availability, which are what customers look for.
7. With parabolic tracking stabilised antenna you would use two antennas on a LEO constellation, one for signal, the other to locate and track the next satellite before switching. Will the new flat panel systems be able to do this with a single antenna?
Michele Franci: The use of two parabolic antennas on LEO or MEO systems stems from the requirement to have one antenna tracking the sunsetting first satellite, while the second would lock on the upraising second satellites. Both antennas carry signal traffic. This approach is necessary in systems requiring a “make-before-break” satellite to satellite handover and is a more robust solution for system supporting a “break-before-make” handover. Several electronically steered FPA systems can generate multiple beams from the same surface, thus acting like a dual antenna system.
Brian Billman: Not every flat panel antenna can achieve this. It is highly dependent on the technology used. Mechanically steered flat panels are not able to achieve multi-beam. There are phased array designs that support multi-beam but this drives up the cost and power consumption even more (areas where phased arrays are already challenged). Also, the additional transmit beams have reduced performance since they share the same hardware. What is really unique about Isotropic’s technology is that we can offer multiple full performance, full duplex, beams at a much lower power consumption without increasing costs. This not only supports NGSO make-before-break handovers but also multiple links across multiple orbits.
Ralph Brooker: Some antennas may be capable of multiple simultaneous, independent beams. Others may have very fast switching speed so the same beam can hop to the next satellite without interrupting the channel (presumably buffering the IP data during the handover). Others may have two panels side by side.
Tony Russell: A true active electronically steered array has the ability to support multiple beams so in principle it can perform the “make before break” function. Please realise that the split or multiple beam operation will come with a performance degradation and that the dual beam operation will be required at low look angles where the array is most challenged.
8. Does Isotropic have any measured pattern data and G/T over scan that is publicly available? Would be interested also in hemispherical plots to better understand grating lobes and regulatory compliance.
Brian Billman: Yes, we have measured both Ku and Ka band prototypes in the anechoic chamber. These prototypes were key in confirming our fabrication processes, assembly tolerances, accuracy of our simulation tools, pointing algorithms, calibration routines, and the performance of our optical beamforming modules. Regulatory compliance was also one of the most important aspects of these tests. While we are not publicly sharing this data, I can report that our team, our customers, and our investors were extremely happy with the measured results for both gain and regulatory compliance.
Bill Milroy:For those “true antenna techies” who might be (generically) interested in reviewing measured phased-array antenna patterns (various “skew” cuts at various “elevation” angles) here’s a (publicly-available) FCC link to a large compilation of antenna patterns, metrics, and technical details for a particular Ku-band phased array (employed in Gogo’s “2Ku” IFC System.) Measured G/T for this particular IFC antenna system is 18 dB/K at broadside (zenith) dropping to 15, 12, and 9 dB/K at 30o, 15o, and 10o elevation. www.licensing.fcc.gov/myibfs/download.do?attachment_key=1055681
9. Does the lack of progress on Flat Panel costs, mean that market share could ultimately be lost to low-cost products being produced in the Far East?
Tony Russell:The interest in developing flat panel arrays is global. An example of this may be seen at http://www.xphased.com/
10. How will the LEO constellations compete with 5G in the consumer market?
Michele Franci: For OneWeb, it’s not about competition, but cooperation because we will work with Telcos to widen the opportunities of 5G. Satellite is a vital element of the 5G “network of networks” and all cellular generations from 2.5G to 5G are supported by the OneWeb system in the same way.
We also had a few questions that were only partially responded to, or the answers were not quite clear. Some answers are provided here:
11. What kind of parabolic (small) dish is ready for consumer market today?
Michele Franci:We are not focused on the consumer market, but once we have our local partners and resellers network, we expect consumers will be able to purchase User Terminals through those channels. The key features will be:
• Users Terminals will vary in size to accommodate various customer needs
• Power efficient
• Easy satellite acquisition
• Standards-based network integration
• Cutting edge LTE network enabling mobility, higher throughput/ lower latency
Ralph Brooker:For GEO satellite service, there are already, of course, many low-cost fixed terminals (US$500-US$100) with parabolic reflectors in the 60-90 cm range. They are in consumer service in the U.S., Europe, and other regions. There are some small marine gimbal-stabilised parabolic terminals in the US$3k and up price range. These can be often adapted for LEO service, although two may be required to handoff between LEO satellites as they pass over.
12. What is the recurring cost of solid-state active arrays? Isn’t most of the cost building the foundry?
Ralph Brooker:Where to start! Monolithic Microwave Integrated Circuits (MMICs) tend to use a lot of surface area (transmission lines, radiating elements, power amp transistors) and you need advanced materials and processes to work well at 14 or 30 GHz. The wafers are expensive compared to Si CMOS and you don’t get a vast number of chips per wafer. The engineering required is also intensive. So, it is a real challenge to make an array of active elements at a low cost. Consider the physics: At 14 GHz the wavelength is about 21mm. To make an array you need a radiating element at least roughly every ¼ wavelength. That means that 60 cm x 60 cm array needs over 12,000 elements. If you could even buy a US$2 LNB/BUC chip for each element, that would be (hypothetically) US$24,000 just in chips! Clearly you need much more creative solutions, and you are seeing some very smart ideas from ThinKom, Isotropic, and many others. GVF is working on a training course about antennas which will cover this topic at a systems engineering level.
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