For anyone that’s ever been broken down along a remote stretch of highway and desperately searched for a cell signal, knowing that a constellation of communications satellites is zipping by overhead is cold comfort indeed. One needs specialized gear to tap into the satphone network, few of us can justify the expense of satellite phone service, and fewer still care to carry around a brick with a chunky antenna on it as our main phone.
But what if a regular phone could somehow leverage those satellites to make a call or send a text from a dead zone? As it turns out, it just might be possible to do exactly that, and a Virginia-based startup called UbiquitiLink is in the process of filling in all the gaps in cell phone coverage by orbiting a constellation of satellites that will act as cell towers of last resort. And the best part is that it’ll work with a regular cell phone — no brick needed.
Time, Divided
The idea behind UbiquitiLink’s plan to fill in the dead zones is simple, and it’s based on the fact that space really isn’t as far away as it seems; if you could somehow drive straight up, low Earth orbit is only a couple of hours away. The satellites that will form the backbone of the UbiquitiLink network will be in a somewhat higher orbit — around 310 miles (500 km). Still, that’s not really all that far away (at least in terms of radio frequency propagation) over a path that is, for the most part, free from the attenuation caused by terrestrial obstructions.
UbiquitiLink has done the math and calculated that off-the-shelf phones have just barely enough RF oomph to connect to a satellite over a line-of-sight path, making a network of orbiting cell towers at least plausible. Making that practical is not just a matter of power, though. Some software trickery will be involved on the terrestrial end.
Cellular networks are all based on multiple access methods, which are schemes that allow the resources of a single cell site to be shared among multiple users. Time-division multiple access (TDMA), where a data stream is assigned to a specific timeslot that is negotiated between the cell site and the user, is the multiple access method that was used in most 2G cell phone networks. TDMA was also used in conjunction with code-division multiple access (CDMA) in 3G networks. Although these networks may be approaching end-of-life in a 4G and soon a 5G world, UbiquitiLink’s efforts to spoof the system started with TDMA.
The problem with a time-division system is that the further a cell phone is from a cell site, the longer it takes for the RF waves to travel between the two. Even at approximately the speed of light, the delay can be enough for one timeslot to overlap into another. This requires a synchronization step that determines how far the phone is from the base, and if the phone is far enough away — about 35 km, or 22 miles — the signal will actually arrive too late for its assigned time slot. Even though the transmitter in the phone may have the power to cover more than 35 km, signals from that far away will be unceremoniously dropped.
Fooling Your Phone
This would seem to preclude the use of orbital cell sites, which will always be an order of magnitude further away than the furthest allowed connection. However, UbiquitiLink has patented a technique that amounts to false advertising on the part of the satellites. TDMA networks use a timing advance signal to tell the mobile phones within the cell how far they are from the base station, which in turn is used by the phone to retard the timing of its transmission so its signal arrives at the right point in the timeslot. Since it’s up to the base station to send the timing advance, UbiquitiLink’s orbital cell sites simply send a constant value corresponding to a tower that’s only 20 km away. The phone thinks it has locked onto a weak tower, but that’s OK.
UbiquitiLink’s modified cell tower software also has to adapt to the Doppler shift caused by the platform’s high speed. But aside from that, the orbital cell sites are pretty much the same hardware and software that would be installed on a terrestrial tower. The backhaul connections between different orbital cell sites and between the satellites and the ground will obviously be wireless, but in almost every way, the UbiquitiLink network will just be a constellation of minimally modified cell towers launched into orbit supporting bog-standard cell phones on the surface.
Out with the Trash
Initial testing of the TDMA version of this system occurred after a test system was sent up to the ISS on a Commercial Resupply Service (CRS) mission in November of 2018. The following February, before loading the Cygnus supply spacecraft with their garbage, ISS astronauts assembled and tested the UbiquitiLink test platform. The spacecraft deorbited and burned in the atmosphere, but not before a solid two weeks of orbital testing time. UbiquitiLink was able to connect cell phones in New Zealand and on the Falkland Islands to the test platform, confirming that their software changes work.
Further tests are scheduled for this summer, with another test platform delivered to the ISS with the CRS mission that flew to the ISS in late June. This time, the Cygnus will have an extended duration mission, giving UbiquitiLink up to six months to test their system. Assuming all goes well, this will open the door for launching actual operational satellites.
https://youtu.be/-ccnWvynQWA?t=41
Like Starlink and other microsatellite concerns that want to provide saturation connectivity from on high, UbiquitiLink plans a constellation of thousands of satellites that will cover most of the surface of the Earth. But they believe with even a small constellation of perhaps a half dozen satellites, users will still be in range of a signal every few hours. It’s not enough for a phone call, of course, but it would be enough to get a couple of texts through, which could be all it takes to get aid in the backcountry or in the middle of the ocean. And the possibilities for supporting really remote IoT sensors and systems are endless.
It remains to be seen how well UbiquitLink’s system will work, and whether it will survive in a crowded marketplace of space-based wireless providers. But by freeing users from the need to buy any special hardware, the company may well have given themselves a competitive advantage over everyone else.
Interesting and logical too, though will come down to the type of plans for initial effective commercial uptake, if at least to earn sufficient to maintain infrastructure and minimal admin, thanks for posting, Cheers
It’s going to be damn near impossible for them to get a tight enough beam pattern to avoid interfering with terrestrial networks.
This is basically the inverse of the primary reason cell phones are still banned on airplanes even when most other wireless protocols are now allowed – you can get the FAA to approve all you want, the FCC will still ban the practice because an airborne participant in a terrestrial cellular network is a major interference issue that fundamentally violates the whole idea of a “cellular” network with spatial frequency reuse.
This is a rather clear problem indeed.
Wouldn’t it just be simpler to build cell towers along “normal” roads. (Ie, a road that is paved with asphalt/similar and sees at least a few (3-5) or more vehicle per day on average.) It honestly doesn’t need to be much of a tower per say, just an antenna pointing in each direction sitting on a semi tall (5-10 meters) pole would be sufficient, after all, the road is where we expect people in need of communication the most.
Instead of a convoluted satellite based system that has a risk of interfering with existing infrastructure and devices.
That already exists: it’s the current cellphone network. The whole point of ubiquitilink (or however it’s spelled) is precisely to cover places that aren’t near roads or anything else. My mom’s house is in a remote area where you have to drive 10km just to get voice service, and a lot further to get data service. If I start hiking into the mountains behind her house, I’m a very long ways on foot from the nearest anything service. I’m okay with that: it’s what we’ve been doing for decades. But this business plan is predicated on people in those areas wanting at least some cellphone service.
Yes, I am fully aware that I were talking about the current cellphone network….
My point were rather to just build out the normal cell phone network in places where one knows that there will be people in need of such service.
A cell tower can after all be fairly cheap to build and maintain. Ie, not aiming for 5G, or even 4G, since they are very expensive, and as you stated, any service is better then no service.
It’s really hard to build out cell towers in the middle of the deep blue sea.
We had such a system (Analog cellular), but the carriers have largely abandoned it. (Probably not enough profit to make up for all the upkeep, leases, etc.)
That begs the question how do they plan on making money with this setup? If you live/break down in some really remote area does making a call incur roaming charges of ~$100 a minute or what?
Analog cellular is circuit switched, so each caller reserves a frequency pair. You quickly run out of bandwidth for even small cells with a small number of customers, which is why analog cellular was abandoned after more than 1% of the population could afford cellphones.
One reason the analog AMPS/NAMPS could get connections from so far away is those phones had more powerful radios than modern phones as the density of cell towers was much lower.
I’m honestly surprised we still use analog two-way radios and wireless mics and stuff like that. is just so incredibly effective now, that analog is mostly just for artistic/hobby/education, and fallbacks when nothing else works.
Not that I think analog is actually more reliable, but it’s different, which means it’s less likely to fail at the same time as a digital system.
Although seeing FM radio go would be a little sad, despite the fact it’s taking up some really great spectrum and would probably sound better in digital.
It would likely cost far more than the potential income to build. There’s not just the hardware, but labor costs and power supply issues.
It’s probably cheaper to launch a rocket to deploy a satellite that can cover everywhere in 1% time slots than it does to deploy thousands of towerrs to provide 100% uptime. It’s like considering the cost to have the phone company run a line out to your cabin.
There would have to be a few frequencies reserved for this and a very limited number of calls through the satellite network. Are standard cellphone frequencies even approved to satellite use?
It sounds like they would have to buy spectrum for this service worldwide and possibly get regulatory approval to use it for satellites.
Yes, it seems oddly convoluted from a technical standpoint.
And hard to implement from a legal standpoint.
And in the end, the main people that finds themselves out in the middle of nowhere and in need of cell service are either stranded on a road that only gets used a few times a day on average. (here on could just build a cheap cell “tower”. (Mainly covering the direction the road is using.))
Or intentionally going out into the middle of nowhere for the experience. (These people usually bring a satellite phone, and also some extra supplies to not get into trouble to start with… (or just one of those emergency beacon thingies that Dave on the EEVblog took apart.))
There’s a lot of areas where I grew up without service still. It’s not as simple as putting a small directional antenna somewhere, or someone would have already done it. These areas are mountainous and the roads meandering. There’s not straight lines and mountains in your way in every direction
Terrestrial cellphone networks suffer from outages. A hurricane can blow the power lines down, after which the towers have about 8 – 24 hours of backup power, and then the network goes down.
It would be very nice if there was a solar powered satellite flying overhead once a day, so you can at least send a text to say “I’m okay” or “500 injured, bring water.”
Surely doesn’t have to be that tight a beam (what Freq ranges for what phones – exclusions ?) for the requisite regions which don’t have conventional cell coverage, of course with managed satellite RF power output and appropriate links to the closest service providers amenable to extra $ just for being there ;-) The coverage is either known or can be determined and existing terrestrial providers would be happy I expect to provide that information outside their normal region for a piece of the action – it’s far less infrastructure than to compete especially in Australia. The satellite(s) then have means to cover those regions selectively so as not to interfere – with a few caveats of course as well as access to various extensions or bandwidths within satellite bands and the service provider ground stations.
In general I see this as “..definitely worthy of further analysis..” not that difficult though tad more sophisticated than simply planning parking spaces ahead of time knowing where you are going given balance of probabilities but, helped tremendously by coverage stats in those traditionally sparse areas. In fact could be pretty straightforward given what I hear about how tight the provider’s management is and how a satellite provider in select regions could be slotted in on appropriate commercial terms…
I don’t think interference will be a problem, at an orbital distance of 500km the signal strength on the ground will be too low to cause significant interference with terrestrial networks.
I’m curious what their long term financial plan is? Do they sell the rights to connect to providers and then users add it to their plan? Will it be a separate plan entirely? Because the problem I see is a simple one. The reason most people don’t own a sat phone is a risk assessment which says, I almost never will need one so why invest in one. These guys are the same way.
The best option I can see is a method for users to check a, this is an emergency box, at which point I can connect to their sats and auto join a pay as you go service embedded in my provider contract. Obviously for hikers or other high risk low service people this is a benefit but again the ones who own a sat phone own a sat phone and the ones who don’t don’t, so I don’t see this changing the game on that front. It needs to be possible for people who did not anticipate the need to spontaneously utilize it.
Another model would be to finance it for the public good. (Like emergency services – EMT, fire departments, Tsunami warnings, various alert systems, etc.) Use it essentially for emergency systems, and fund it using similar mechanisms.
Won’t make you a darling of wall-street, but money isn’t everything.
I’m sure that’s fine with Wall Street. Such things are typically paid for by governments using use fees, public safety levys, etc, as you say.
Governments can and do sign long-term contracts. This provides a good revenue foundation reducing the required investment to get to break-even. Such service is likely limited (phone and low-rate data for individuals, higher bandwidth for fixed video and a relatively limited number of public employees/vehicles. Lynk can then sell higher-margin service to corporate and individual users, either directly, or by way of existing mobile carriers.
Nice to see that GSM is not dead yet.
Btw., searching for UbiquitiLink and GSM yields some documents with technical details:
https://fcc.report/ELS/UbiquitiLink-Inc/1247-EX-ST-2018
I wonder if Ubiquiti Networks will ask them to change their name.
I wouldn’t be surprised if they do. At first I thought this was one of their things.
I bet you’re both right. It would be crazy for them to allow use of the name in such a similar marketspace. I was sure they were involved with it at first, going by the spelling.
looks like they changed their name to just “lynk”. I wonder if Ubiquiti had something to say about the name before. (UBNT makes wireless networking gear)
Yeah, that’s the first thing that caught my attention. And I would bet that UBNT had a say in that, though I am wondering how they managed to hold on to that domain.
I’d wondered if this was a UBNT subsidiary or spinoff, but it doesn’t look like either one. First, different visual design, which seems odd for a subsidiary that includes the name of the parent. Second, the execs and advisers all look like cellular or satellite veterans with no connection to UBNT, and the funders don’t include UBNT.
“In 2021, when Lynk has between 24 and 36 satellites in orbit, users can expect coverage every hour, anywhere between 55 degrees north and south latitudes. With the company’s planned constellation of several thousand satellites by 2023, coverage will be continuous, whether in the middle of the Sahara Desert, the Amazon jungle, or the Pacific Ocean.”
All of which lie within the northern and southern 55th parallel, conveniently enough. So no change, then? Or does “coverage every hour” mean that you will have _some coverage_ during each hour? That sounds not completely rubb, but…
.
Also – inside the 55th parallels – south it makes sense, then it’s basically the Antarctic that is not covered, and I expect they have satellite on the south pole, but 55th north? That’s quite a lot of land that does not get coverage. Basically the whole of Scandinavia, the Baltics (Except southmost part of Lithuania), UK north of Newcastle, (thats the whole of scotland, even a bit of North Ireland) its Iceland, Greenland, quite a lot of Canada (like half?), Alaska, and most of Russia. 55th latitude borders north Germany, ffs.
You forgot Poland.
Scandinavia and the Baltics already have full cellular coverage on 100% of the land area. You have to go to Russia to lose signal, but why would you want to?
But it would be nice for sailors to have signal in the middle of Baltic Sea
I spend a fair bit of time outside of cell coverage areas, so I got a Garmin InReach mini to be able to send SMS messages from anywhere. It uses the Iridium satellite network to get global coverage. It’s tiny, much smaller and lighter than an iPhone. Cheaper, too. Giving up voice capability allows a small, inexpensive package to work well.
It would be nice to avoid even carrying that tiny device. But what’s the business model? Will the carriers just bundle the satellite service in with their plans, or will there be an extra charge per month and/or per message?
Ah. Yep. This seems the better idea. I was wondering if GPS satellites allowed any of this. Obvs the transmitter is not gonna be the same. But tons of phones have a gps receiver. Or is the main article tech using the gps aerial communication to setup the gsm transmission from the phone?
This has nothing to do with the GPS or GPS hardware in phones.
The problem with those mini SMS pagers is that they’re extra devices that people don’t want to carry around just in case. Unless you know you’ll need it, it’s just gonna sit there in the drawer with an empty battery, and when you do need it then it’s either not with you or it’s dead.
That’s the point of spoofing a GSM tower with a satellite. Your regular phone thinks it’s within reach of a regular cell tower – which just so happens to reject phone calls, but you can still send and receive text messages through it.
I wonder about their business model. That seems to have been the issue with previous attempts.
Also, I’m not convinced that the need for this is so big: special application like IOT: will be covered by medium range solutions like Sigfox, cheap LORA and 5G. Satellite will be super expensive, so for that matter, it might make more sense to invest in a proper solution not a 2G hack from space. As far as SAR is concerned, there are already satellite solutions for that. And the idiots who travel the Sahara without a rescue beacon, well, they fall victim to Charles Darwin for a good reason.
How is this “2g hack” not a “proper solution”
Doppler shift pre-distortion, I must read that patent ( WO2012/042490A2 ) that sounds very interesting.
Doesn’t Doppler shift changes the frequency? In that case the pre-distortion would be to shift the frequency in the opposite direction to compensate, did they really patent that?
At the simplest level, yea that is about it. But you really think about it a bit more, there is some subtlety. In the above application you would use one frequency band for point A on the earths surface, a second frequency band for point B and a third for Point C, and so on and so on. And you would need to dynamically adjust each by a different frequency offset when flying over to make it appear to each individual point at ground level that there was no Doppler shift and the pre-distortion would be different for each but could all be pre-calculated and just cycled. A bit like a centipede walking, cycling through various frequency bands when entering different legal jurisdictions.
It could be overturned but I can see why a patent was allocated:
Is it novel (is it new, has never been done before): possibly
Is it non-obvious: debatable
Is it useful (does it have an application): Yes. (planes, UAVs, missiles, satellites, …)
Quadrature Phase Shift Keying applied for a patent in 1984 which only expired today actually! So it is not like there is not a history of patents slipping through that possibly should not have.
@Truth, you said: “Quadrature Phase Shift Keying applied for a patent in 1984 which only expired today actually!”
Interesting, link please?
Actually it looks like it was google patents doing something weird:
https://patents.google.com/patent/US4680777A/en
It is now showing
“2019-08-27 Application status is Expired – Lifetime”
And yesterday it was showing:
“2019-08-26 Application status is Expired – Lifetime”
This a thingy in search of a whachamacallit. Satellite phones are cheaper than iPhones and are hardly “bricks”. Yes, the per minute cost is higher, but you can actually make a call, and what makes anyone think the system described in the article would be any cheaper? It’s high tech bumbaclot.
Cool, but with so many companies looking to build such large satellite constellation, I’m worried that just one mistake will result in my grandchildren and their grandchildren being trapped on earth ( Kessler syndrome).
Have you seen what is up there already http://stuffin.space/
I’d be more worried about some idiots deciding that it was a good idea to militarize space (not looking at any countries in particular), than an accidental Kessler syndrome. The odds are Kessler would deliberate be triggered, with hardware designed to optimise and maximise the effect. A ultra cheap doomsday weapon.
There is a service right now to cover wilderness or far flung places. Go to Amazon and search on Spot 3 Satellite GPS Messenger. You can have a wireless panic button that sends your GPS position to several satellites if you are in trouble. You can also send and receive non-emergency text messages on the unit.
Read some reviews before looking at Spot/Globalstar. We went through this a few months ago. Spot’s coverage is, uh, spotty. Literally. The satellite antenna patterns are patchy and cover most of the landmass, but still only a fraction of earth’s surface. The messenger service is better than their phones (which are essentially useless for marine or northern work), but still useless in (for example) Hawaii.
Get the feeling that a lot of commenters here don’t get out much.
There is a lot of the world with no cell phone coverage (get away from the cities
and major highways). Way back before cell-phones (okay, a couple or 3 decades ago)
people went out in these areas and lived, and worked, and played, and if something bad happened, somebody had to go and get help.
Lots of people still live and work and recreate in these areas. The common case is not the Sahara, it is going out to gather wood or pick huckleberries, or go fishing. Not wealthy people,
not technically savvy people. Just common people. Most of them don’t even know that satelite radios exist. Many could not afford them, and they probably would not be cost effective.
For them to all have satelite radios would be a tremendous waste of resources.
Man, with the Doppler shifts and time dispersion, it’s a real hassle to use TDMA. Lowest common denominator savages. Pity plain old CDMA got deprecated. It would be ideal for this application.
As another poster has noted, there’s an easier and far more reliable solution for those who need communication links in remote areas. That’s texting devices such as Garmin’s InReach series, which use already-in-orbit Iridium satellites. The plans are reasonable and flexible. They’re also a lot more versatile than just patching together an iffy communication system using cell phones in ways they’re not intended.
https://explore.garmin.com/en-US/inreach/
Actually, if this system works as intended, why would anyone get an inreach when they already have a normal phone.
LoRa modulation has approx. an order of magnitude greater range than other digital UHF comms & is additionally fairly Doppler shift tolerant. I see it bring eventually inbuilt into smart phones to at least suit non cellular txt messaging. Refer Lacuna’s recrnt satellite based approach => http://lacuna.space
Here’s an update =>
http://lacuna.space/2019/06/12/lacuna-space-achieves-major-milestone-for-lora-in-space/
I’m sure that’s fine with Wall Street. Such things are typically paid for by governments using use fees, public safety levys, etc, as you say.
Governments can and do sign long-term contracts. This provides a good revenue foundation reducing the required investment to get to break-even. Such service is likely limited (phone and low-rate data for individuals, higher bandwidth for fixed video and a relatively limited number of public employees/vehicles. Lynk can then sell higher-margin service to corporate and individual users, either directly, or by way of existing mobile carriers.