Wireless Waffle - A whole spectrum of radio related rubbish
Oh, 3Bsignal strength
Wednesday 24 July, 2013, 07:44 - Satellites
Posted by Administrator
o3b logoSatellite officionados will no doubt be aware of 'O3b' but to the rest of the world, the launch of their first four satellites probably passed them by. O3b stands for 'other three billion' and is meant to highlight the plight of the significant proportion of the world's population who do not have access to high speed internet connections. O3b's role is to provide a 'backbone in the sky' which will allow places that are remote from terrestrial infrastructure to have high speed connections.

The idea is not that new. 20 years ago, Teledesic had much the same idea. The two networks share a lot of common features:
  • They both use Ka-band spectrum (around 18 and 28 GHz). At these frequencies, even small dishes have very narrow beams, requiring accurate pointing.
  • They both use low(er) orbits than the geostationary arc. The lower orbits reduce the time delay normally associated with satellite communications but require that the dishes are able to track the movement of the satellites.
  • They both have big-name backers. Microsoft was an investor in Teledesic. Google is an investor in O3b.
Unfortunately Teledesic's business model was usurped by delays in the launch of the system which led to terrestrial telecommunications quickly catching up and surpassing the capabilities of the satellite system. O3b on the other hand, is looking to offer connection speeds of up to 600 Mbps which is highly competitive in areas which do not yet have access to internet delivered via fibre. So is everything hunky dory? with O3b? Let's take a look...

Wireless Waffle has discussed the different bands used by satellites before. Ka-Band is the band of choice for new broadband satellites as it's used less than the now almost saturated Ku-Band. The thing is that there are an increasing number of satellites using the band, the majority of which are in geostationary orbits. As the O3b satellites are in a medium earth orbit (MEO), and thus move through the sky when seen from the ground, it is quite feasible that they could end up positioned between a dish on the ground, and a geostationary satellite. In these cases, there is the potential for the O3b satellite to cause interference to the dish on the ground. As there are potentially millions of such dishes, ensuring that the O3b constellation is 'switched off' when it is in a position to cause such interference is an interesting technical challenge.

get out of my cloud

Then there's the issue that as the satellites appear to move in the sky, ground stations for O3b would require tracking dishes. Much development has been done to try and develop dishes which can track the movement of satellites without the dish itself needing to move. Such dishes would be ideal for use on trains, aircraft or cruise ships to circumvent the need for tracking dishes on moving vehicles. The same idea could be applied to ground stations that are fixed but satellites that move. However this is not the plan for O3b. The plan is to have traditional steerable satellite dishes which track the satellite through the sky. And as it takes time to move a dish around, two will be used with the second picking up a connection from a second satellite as the first dish loses its connection when the satellite passes over the horizon.

Two steerable dishes makes for a complex system and one which will require significant and regular maintenance costs, and maintenance by skilled engineers who are not (currently) likely to be present in large numbers in the kinds of areas that O3b wishes to serve. There is also the question of what happens when the service is handed over from one satellite to another. Such a hand-over could introduce a variable delay in the connection (technically, known as 'jitter'). One solution to this would be to have a buffer to stabilise the connection, but adding a buffer adds a delay and it is precisely to try and reduce delay that the satellites are in a lower orbit to start with. Oops!

Current Ka-band satellite services typically offer connection speeds of around 20 Mbps and use 65 or 80 cm dishes. Delivering 600 Mbps requires a bit more effort and as such the steerable dishes for O3b will each be 4.5 metres in size! At Ka-Band this means they will have a beamwidth of less than 0.2 of a degree, requiring highly accurate tracking. Not to mention the fact that 4.5 metre dishes are large and heavy and take up a lot of space. If you think about the intended market for O3b, which is rural area far from traditional infrastructure of any kind, running two, highly accurate, steerable 4.5 metre dishes is not the kind of technology which would easily blend in with the environment. And where do you get a power source to drive them with?

dish hut

Putting these technical issues aside for a minute, there is then the question of speed to market. Many of the far flung places that O3b is looking to serve are already beginning to be connected via fibre, whether undersea or overland. Take the Pacific Islands, slowly but surely, these are being connected to the world via subsea fibre. Fiji, Guam and Hawaii have long had connections, but Norfolk Island, New Caledonia, Vanuatu, Wallis, Samoa and American Samoa are due to be connected via a project called Hawaiki Cable (though it's fair to say that a previous such projects known as SPIN did not materialise). Perhaps O3b has the upper hand here, then again if Hawaiki goes ahead, it will offer connection speeds nearly a thousand times faster than O3b.

Would you pour your hard earned money into O3b shares? Don't decide just yet as there's one other issue we need to talk about... the Van Allen belt. You may have heard of this. It's a region of space above the Earth which is full of particles charged by solar energy but trapped by the Earth's gravity. It is one of the more unfriendly space environments and the O3b satellites flying at just over 8000 km above the Earth will sit right in the middle of it. This gives them around 100 times the dose of radiation that a satellite in geostationary orbit would experience and as a result makes them more susceptible to radiation damage of various kinds. There are currently no commercial satellites (other than O3b) operating in the Van Allen belt.

Of course all these obstacles are worth the effort if the end services can be supplied more cheaply than competing technologies. O3b's pricing is not yet clear but it will have to compete with other Ka-band services such as Inmarsat's Global Xpress. This will give you a connection of up to 50 Mbps for prices purported to be around US$3000 per month. At rates of income in some countries, it would require an awful lot of users to club together to raise that kind of finance. It is therefore to be hoped that O3b can offer a service that is more cost effective. With the cost of the dishes alone likely to be at least US$50000, that seems rather unlikely.

angry dinosaur

Perhaps a better description of O3b would be 'over 3m big'. Still, it looks as if their dishes will provide good protection against angry dinosaurs!
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Is the European Commission's Spectrum Inventory nuts?signal strength
Wednesday 27 February, 2013, 08:20 - Amateur Radio, Spectrum Management, Satellites
Posted by Administrator
Over in Brussels, the European Commission, through the direction given to it by the Radio Spectrum Policy Programme (RSPP), is trying to identify 1200 MHz of spectrum that can be made available for 'wireless broadband' services. At present there is 1025 MHz of spectrum available for such services including:
Band Allocation Total Spectrum
Digital Dividend 791 – 821 // 832 – 862 MHz 60 MHz
900 MHz 880 – 915 // 925 – 960 MHz 70 MHz
1800 MHz 1710 – 1785 // 1805 – 1880 MHz 150 MHz
2.1 GHz (FDD) 1920 – 1980 // 2110 – 2170 MHz 120 MHz
2.1 GHz (TDD) 1900 – 1920 MHz
2010 – 2025 MHz
35 MHz
2.6 GHz (FDD) 2500 – 2570 // 2620 – 2690 MHz 140 MHz
2.6 GHz (TDD) 2570 – 2620 MHz 50 MHz
3.6 GHz 3400 – 3800 MHz 400 MHz
Total 1025 MHz

Finding another 175 MHz to make the goal of 1200 MHz is therefore surely not such a big ask. However, there are issues with the spectrum that is currently available. The 3400 – 3800 MHz band accounts for 400 MHz or a good third of it and despite already being allocated to broadband wireless in Europe, it has not been very popular. The slow take-up is partly due to a lack of mass market products for the band and the poorer propagation at these higher frequencies, but is also due to the need to protect certain C-Band satellite downlinks which remain in the band. This also forms the 9cm amateur band. It therefore seems sensible that if new spectrum is to be found, it ought to be below 3 GHz in order that it will prove popular enough to actually be put into use.

counting moneyTo try and identify 'underused' spectrum, the European Commission is conducting a spectrum inventory whose purpose is to firstly examine the availability and use of spectrum and then to consider the future needs to try and match supply with demand. The first part of this inventory, a study which examined the extent to which each spectrum band is used was published in late 2012. The initial findings of the consultants who undertook the study were that the bands with the lowest current usage and thus which might be candidates for re-allocation were:
  • 1452 – 1492 MHz. This band is set aside for DAB radio services, however it has remained virtually unused. The ECC have now recommended the re-allocation of this band for mobile services after pressure from Ericsson and Qualcomm to do so. This is therefore a 'no brainer' or a 'done deal'.
  • 1980 – 2010 // 2170 – 2200 MHz. This band is currently allocated for 3G mobile satellite services to complement terrestrial 3G services. One satellite (Eutelsat 10A) was launched with a payload that is active in this band, but it failed to deploy the dish correctly and as such the band remains largely (though not completely) unused. It would seem churlish to take this away though, when there is still scope for it to be commercialised for its intended purpose. Perhaps some form of sharing using a complimentary ground component could be envisaged.
  • 3400 – 3800 MHz. This was identified as being underused… 'Quelle surprise' as they say in Brussels!
  • 3800 – 4200 MHz. This is also part of the C-Band satellite downlink frequency range but has also been used for fixed links in some countries. Fixed links can be carefully controlled so as to avoid interference to satellite ground stations: it is unclear how a more widespread roll-out of services in this band would be feasible. This also fails the 'below 3 GHz' test.
  • 5030 – 5150 MHz. This band is allocated for aeronautical use and was intended to be used for a new microwave landing system (MLS) to replace existing landing systems and for aeronautical mobile satellite services (AMSS). Very few airports or airlines have adopted MLS (London Heathrow and British Airways being two of the few who have done so) and no AMSS services in the band have been launched. If 3.5 GHz is not popular though, it seems unlikely that 5 GHz will be any more welcome.
  • 5725 – 5875 MHz. This is a band which is available on either a licence exempt or a lightly licensed basis in most European countries for use with WiFi (802.11a) and other low power services. Being well over 3 GHz it is unlikely to be popular. It also forms a large chunk of the 6cm amateur band.
In total this represents another 770 MHz of new spectrum, more than enough to deal with finding an extra 175 MHz. However the majority of this is above 3 GHz and experience has shown that the appetite of operators for this spectrum is relatively small. The question therefore ought to be whether there is spectrum below 3 GHz which could be made available.

One option on the table, though not identified through the inventory, is the frequency band 2300 – 2400 MHz. It was identified at the 2007 World Radio Conference as a candidate for IMT (the ITU code for wireless broadband). It is already in the 3GPP standards for LTE, where it is known as the mysterious 'Band 40'. The ECC has considered the use of this band for wireless broadband services and concluded that it is quite possible. Sweden and Australia have already handed all of the band over to wireless broadband use, and many other countries (especially in Asia) have licensed part of it. One of the big problems with this band in Europe is that it is heavily used by governmental (read 'defence') services who are already smarting from the loss of many other bands over the past years and are in no mood for another re-farming exercise to release this band. Oh, and it represents the vast portion (and the most useful bit) of the 13cm amateur band.

meteosatMeanwhile, over in the USA, the FCC has also recently assessed the possibility of reallocating some the frequency band 1675 -1710 MHz for wireless broadband uses. This band is currently used for the downlink for meteorological satellite services, however few satellites venture above 1695 MHz (with the possible exception of a couple of NOAA satellites, the Chinese Feng Yun satellites and the polar orbiting METOP) and there is almost nothing above 1700 MHz, unless you count satellites yet to be launched (such as GOES-R).

Given the location of this spectrum, directly adjacent to the existing 1800 MHz band, and given that the associated pairing is also largely unused it might easily be possible to, say, extend the 1800 MHz band by 2 x 10 to become 1700 – 1785 // 1795 – 1880 MHz. Keeping the spacing between the up and downlinks would simplify the adoption of the new spectrum (in the same way that GSM became E-GSM). The 10 MHz gap in the middle is rather small which can cause handset manufacturers problems, but there are ways this could be dealt with. The loser here (other than some yet-to-be-launched satellites who could surely locate their downlink in the remaining part of the band) are radiomicrophones who are allocated 1785 – 1800 MHz. A screaming case of 'use it or lose it' if they are to retain this allocation.

And whilst we're pairing up things, how's about extending the 2.1 GHz band? The lower part of the pair, 1900 – 1920 MHz, is already licensed, albeit for TDD services. The upper part of the pair, 2090 – 2110 MHz is another of those military bands that would prove difficult to squeeze. The bigger problem here is that it contains sensitive satellite uplinks that are easily interfered with. Nonetheless, there was a terrestrial wireless network licensed in the band in the UK (Zipcom), if never actually launched.

So far, we have identified the following extra spectrum:
Band Allocation Total Spectrum
L-Band 1452 – 1492 MHz 40 MHz
Extended 1800 MHz 1700 – 1710 // 1795 – 1805 MHz 20 MHz
Extended 2.1 GHz 1900 – 1920 // 2090 – 2110 MHz 20 MHz (20 MHz was already available)
2.1 GHz MSS sharing 1980 – 2010 // 2170 – 2200 MHz 60 MHz (shared with satellite)
2.3 GHz 2300 – 2400 MHz 100 MHz
Total 240 MHz

That makes 240 MHz of potential new sub-3 GHz spectrum without too much pain and done in a way that is largely compatible with existing mobile bands, though not with existing defence or satellite sensitivities. Given the recent auction prices for spectrum, 240 MHz across Europe is worth something in the region of 75 billion Euro. So what would it cost to release it?nuts
  • L-Band is free in every sense of the word. Except possibly in the UK where it is owned by Qualcomm but presumably as they have been lobbying for it to become available for mobile services, they would have no qualms about using it for such. Cost: peanuts.
  • Extended 1800 MHz The main affected party here are some meteorological satellite downlink sites. These are few and far between and could be protected through the use of an exclusion zone. Cost: cashew nuts.
  • Extended 2.1 GHz The number of military satellites using the band 2090 – 2110 MHz is difficult to ascertain (for obvious reasons). There is also a need to re-farm the band 1900 – 1920 MHz. Cost: macadamia nuts.
  • 2.1 GHz MSS sharing In theory there is nothing to stop this taking place even with a satellite already launched. To be completely fair, it would only be reasonable to recompense the licensees (Solaris and Intelsat) for their investments. Cost: pistachio nuts.
  • 2.3 GHz Those defence boys have big toys (and big guns) that would be costly to replace. That being said, only around 40 MHz of this band is necessary if the target is 175 MHz and not 240 MHz. Surely releasing 40 MHz can’t be that difficult no matter how big your toys. The fact that the band is destined for TDD means that it doesn’t even need to be the same 40 MHz in each country. Cost: pistachio nuts.
Wireless Waffle claims no particular ownership of the proposals above, they are all kicking around here and there. A few (tons of) nuts seems a small price to ask to tackle the issues required to get things moving. Even a ton of macadamia nuts (the most expensive nut) would be less than 0.1% of the value released.

Alternatively, perhaps radio amateurs who stand to lose the 13cm, 9cm and 6cm bands might wish to launch a counter-bid? After all, they’re replete with nuts (in a good way)…!
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(Not) A Hope In Heavensignal strength
Tuesday 29 January, 2013, 12:34 - Spectrum Management, Satellites
Posted by Administrator
Following the recent Wireless Waffle post about Wes's excellent Soldery Song, it has been noted that the terms 'C-Band' and 'Ku-Band' were thrown around casually, as if everyone understands what these mean. For the benefit of those who don't, here's a short description of what they're all about:
  • C-Band (in satellite terms) refers to frequencies in the range of roughly 4 to 8 GHz. C-Band satellites are commonplace in areas where there is very heavy rainfall (eg tropical areas) as, using relatively low microwave frequencies, signals propagate better and suffer fewer rain fades. It's not the total amount of rain that matters, it's the voracity of the downpours.
  • Ku-Band refers to frequencies roughly in the range of 10 to 15 GHz (the 'roughly' refering to the fact that uplinks and downlinks work in different bands that may or may not be within this range but are at least somewhere nearby). Ku-Band is the band most commonly used for digital satellite television broadcasting anywhere that it doesn't rain too heavily (eg most non-tropical areas). In many areas, the geostationary arc is near saturation in Ku-Band, with satellites positioned every 2 degrees or so. Some satellite operators have tried to launch broadband internet services in this band but the high levels of congestion make it difficult to find the space to do so.
  • Ka-Band refers to frequencies roughly in the range of 20 to 30 GHz. Ka-Band is the relative newcomer on the block (though Italsat F1 conducted some tests in this band in the early 1990s). With Ku-Band becoming congested with broadcasting, satellite operators wishing to offer broadband services are increasingly turning to Ka-Band to do so and it is fast becoming the most hotly contested band for new satellite services. Already popular in the US, it is now being successfully commercialised in Europe and Africa. In emerging countries, where terrestrial (including wireless) broadband services are unlikely to be rolled-out any time soon, the use of Ka-Band satellite broadband is likely to open up Internet access to millions of people who wouldn't otherwise have a hope of getting a decent connection.

newsatlogoIt is perhaps no surprise that in the battle to gain access to Ka-Band, some of those doing the fighting are going to lose out. This seems to have happened to Australian satellite company NewSat. Recently both Morgan Stanley and Lazard have pulled out of the programme raising funds for the launch of NewSat's Jabiru 1 satellite. Digging into the economics of NewSat, it appears that the numbers just don't add up. The cost of their capacity would be around 50% higher than that of existing Ka-Band satellite operators, which might be a difficult sell when trying to raise lots of capital to build and launch a new satellite.

doesnt add upFrom the figures on their web-site, NewSat were going to pay Lockheed Martin US$550 million to build and launch their 'bird'. The resulting satellite would operate in a total of around 8.4 GHz of Ka-Band spectrum. Compare that to UK satellite company Avanti who paid US$400 million for their bird, but which accesses 11 GHz worth of Ka-Band spectrum. Do the maths and you see that NewSat would be paying approximately US$66 million to access each GHz of spectrum, whereas Avanti paid only US$36 million. This difference in cost is borne out in prices too, with NewSat claiming to be aiming to charge customers US$1.3 million for a transponder for 12 months. The equivalent price for Avanti is around US$0.9 million.

This may not yet be a Ka-tastrophe (groan) or even a Ka-lamity (double groan) for NewSat. NewSat suspended trading in its shares in November to give it time to re-think it's financing strategy. Maybe there is still a 'hope in heaven' for those communities that NewSat was intending to serve, if, of course, the other satellite operators don't get there first!
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Soldery Songsignal strength
Sunday 23 December, 2012, 23:02 - Radio Randomness, Satellites, Much Ado About Nothing
Posted by Administrator
It seems there are very few songs which touch on the topic of satellite communications unless you count:
  • Sleeping Satellite by Tasmin Archer;
  • Satellite by Lena (Germany's Eurovision winner in 2010); and
  • Satellite by Oceanlab.
But none of those songs are really about satellite technology as such, they just happen to have ‘satellite’ in their title. There are, however, some songs which have lyrics that are actually about satellites. For example:
I'm just talking to a satellite,
Twenty thousand miles up in the sky each night

Taken from Electric Light Orchestra's Calling America.

There’s also:
I saw two shooting stars last night,
I wished on them but they were only satellites,
It's wrong to wish on space hardware.
I wish, I wish, I wish you'd care.

Taken from Kirsty Macoll's New England.

So it was nice to be alerted to a piece of work which is not only about satellites, but is very specifically endorsing the use of C-Band satellite services (3400 – 4200 MHz) over and above the use of Ku-Band (10700 – 12500 MHz) in sub-Saharan Africa where C-Band reception is more reliable than Ku-Band due to the fact that it deals with rain fading much better than Ku-Band does.

The song is by Cameroonian artist Wes. In it, he laments the loss of his Ku-band equipment, and the main thrust of the song is that he is short of some solder with which to complete the installation of his new C-Band parts. The video has him stood in front of his non-functional C-Band dish whilst his team try to dance their way into fixing the problem. Eventually they set off on a trek to try and get him some solder as the dancing, no matter how energetic, is clearly not working.

The only odd thing is that there is an Asian lady who, all the way through the song, keeps going on about her blasted spade. Still, it all adds to the ambiance.

The song is called ‘Soldery Song’, and you will need to watch the video whilst at the same time reading the lyrics below as it is quite hard to follow what he is saying due to his strong African English accent (the spade lady's incessant moaning about her spade is shown in brackets)...

SOLDERY SONG – WES


Soldery Song – Wes by jibou

(My Spade, where’s my spade?)

Soldery song: me need a solder
Me got me some parts, now it's me too,
Old part me chuck, and new me part, yeh?

Soldery song: me need me a soldery solder
Me got me some parts, now it's me too,
Old part me chuck, and me new part, yeh?

I throw a my Ku away, melt some solder, done my way
I throw a my Ku away, melt some solder, done my way

Bring us C-band way (with a spade?)
One-a-where they can go?
Hey, I meant to check.
(Spade, yeh, yeh, yeh, yeh!) x 2

Soldery song: hoo hoo hoo hoo hoo, me need a solder
Me got me some parts, now it's me too,
Old part me chuck and new me part, yeh?

I throw a my Ku away, melt some solder, done my way
I throw a my Ku away, melt some solder, done my way

Bring us C-band way (with a spade?)
One-a-where they can go?
Hey, I meant to check.
(Spade, yeh, yeh, yeh, yeh!) x 2

No more can I Ku, new me parts C-band
No more can I Ku, new me parts knackered!
No more can I Ku, new me parts C-band
No more can I Ku, new me parts knackered!
No more can I Ku, new me parts C-band
No more can I Ku, new me parts knackered!

I throw a my Ku away, melt some solder, done my way x 4

Bring us C-band way (with a spade?)
One-a-where they can go?
(Spade, yeh, yeh, yeh, yeh!)
Bring us C-band way (with a spade?)
One-a-where they can go?
Hey, I meant to check.

No more can I Ku, new me parts C-band
No more can I Ku, new me parts knackered!
No more can I Ku, new me parts C-band
No more can I Ku...
(Spade, yeh, yeh, yeh, yeh!)

Perhaps some kind Wireless Waffle reader could purchase some solder and send it to Wes to get his C-band equipment up and working. Oh, and whilst you’re at it, give the poor lady a spade too.
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