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I think the last time that the Loon project item was posted here a lot of the same comments were made. I think it was verified that they are flying at the 60kft

I think the last time that the Loon project item was posted here a lot of the same comments were made. I think it was verified that they are flying at the 60kft - 90kft range where the winds are typically mild and in the 20mph range. I think one problem I see with it is that ordinary smart phones won't work because they transmit at around 100mw and they won't reach that altitude, you will need an earth station that is capable of at least a couple of watts and presumably then it would act as perhaps a wifi hot spot to serve some remote area. I think in that scenario, then it makes sense as a way to serve remote sparse areas. You are simply not going to be able to get the capacity at that distance to serve downtown San Fran. Also, the issue of backhaul is a question mark in my mind. There is no Google fiber up there, so they will need probably some sort of Microwave link back to earth to connect to the internet. That can be problematic, those types of links are typically very directional so you might have to have steerable antenna's at least on the earth end, which is pretty expensive to do. So I am not sure how they plan on dealing with that part.

dubcanada 12y ago
Cell phones can transmit up to 50 miles depending on what it uses, CDMA is max at around 38 miles? That seems more then enough to reach 60kft - 90kft
- zw123456 12y ago
  hmmm, not with 100mw, in the old days of CMDA perhaps if the phone had 600mw which some did back then. But Loon is using LTE as I understand it, and I think it said they are using unlicensed spectrum, which, although I have not seen it spelled out, I am guessing in the 5.8Ghz band but even at 2.4Ghz, you are not going 50 miles on 100mw especially not since LTE is not CMDA, in the downlink LTE is OFDMA and in the uplink SC-FDMA, both of which have a much larger Peak to average ratio than spread spectrum so unless you are using an extremely narrow beam antenna (hard to aim while moving), that signal will probably be below the receiver sensitivity).
  - hengheng 12y ago
    I could imagine more TX power on the balloon (nobody's in the way so it shouldn't do damage), as well as more sensitive RX antennae, since there isn't the same size or weight restriction as on an airplane or a satellite. Come to think of it, an unmanned balloon is actually the wet dream from an antenna standpoint.
    - zw123456 12y ago
      Yup. The downlink is always easy (from the tower to the phone). The uplink is always the weakest link because the size of the device, the limited battery the limited size of the antenna due to the form factor of the phone and so on. If it was strictly a broadcast solution it would be a lot easier, but even if you are streaming youtube, you still need the uplink for TCP and so on.
raldi 12y ago
> I think one problem I see with it is that ordinary smart phones won't work because they transmit at around 100mw and they won't reach that altitude, you will need an earth station From the article: "When Loon started, Google was testing a system that delivered Internet service to antennas on people’s homes. Mathe explained that this was due at least partly to technology limitations. Project Loon is now capable of sending signals that can be picked up by the smaller antennas on phones."
- zw123456 12y ago
  Picking up is one thing, getting the signal back from the phone with it's small antenna and low power transmitter seems problematic. But perhaps they have solved that somehow. At those distances, I am guessing the uplink would be very limited due to this. Keep in mind, that cellular carriers over time want the signal of each phone reduced. The reason is that for cellular, to get the capacity up, you want to have more cell site, each site re-uses the same spectrum of the site next to it, so if all the phones had higher power they would all be interfering with each other. They just are not designed to go those kinds of distances. Most cell radii is in the 1 - 5 mile type of range usually. Again, for capacity reasons. In the early days when there were fewer towers spaced farther apart the phones had more power (remember the old "brick phones").
  - sangnoir 12y ago
    > In the early days when there were fewer towers spaced farther apart the phones had more power (remember the old "brick phones"). Citation needed. What makes you think newer phones have less transmission power than old brick phones? The working range of a cell site (the range which mobile devices connects reliably to the cell site).. is between between 50 to 70 km (30–45 miles)[1] 1. https://en.wikipedia.org/wiki/Cell_site#Range https://en.wikipedia.org/wiki/Cell_site#Range
runeks 12y ago
> I think the last time that the Loon project item was posted here a lot of the same comments were made. I think it was verified that they are flying at the 60kft - 90kft range where the winds are typically mild and in the 20mph range. From the article: "In the same time it took the Earth to complete half of its annual orbit of the sun, our record-breaker managed to circumnavigate the globe 9 times, [...] soaring to a maximum height of 21 km and drifting over more than a dozen countries across 4 continents." So the maximum altitude reached was 21 km. Also, won't increasing the antenna size on the balloon enable reception of a weaker signal? Although the antenna size increases by a factor of πd^2, where d is the distance between sender and receiver. So an antenna 80 km away needs to be 64 times larger than an antenna 10 km away in order to compensate for the weaker signal.
- zw123456 12y ago
  Yes, but a larger antenna will have a narrower beam width so it gets harder to aim it in the right place especially with a platform that is moving. If the antenna beam width is too narrow, you end up needing mechanically steered antennas to keep on target, which are expensive and weigh a lot. Just to level set, I am not being a negative nelly here, I think this is a super cool idea. It is just every time I read an article about it there is so little technical information that I am left with a million questions in my mind that I wonder how to solve.
tim333 12y ago
You could always use non-normal cell phones. I used a Thuraya sat phone for a while and it worked fine to a satellite 35,786 km away. Apparently the transmission power is about 2W, they cost about the same as an iPhone and weigh 140g or so. Mine worked fine off a solar panel. So these things can be dealt with, presumably more easily for a ballon 30km away than a geostationary satellite. (Here's one on amazon http://www.amazon.com/Thuraya-XT-LITE-Satellite-Phone/dp/B00RBQYO5I http://www.amazon.com/Thuraya-XT-LITE-Satellite-Phone/dp/B00... )
- hobarrera 12y ago
  The cost of these phones (due to lack of mass production) is probably much higher. There's also the issue of no roaming - users can't go into/out-of that region with existing devices.

dubcanada 12y ago

Cell phones can transmit up to 50 miles depending on what it uses, CDMA is max at around 38 miles? That seems more then enough to reach 60kft - 90kft

zw123456 12y ago
hmmm, not with 100mw, in the old days of CMDA perhaps if the phone had 600mw which some did back then. But Loon is using LTE as I understand it, and I think it said they are using unlicensed spectrum, which, although I have not seen it spelled out, I am guessing in the 5.8Ghz band but even at 2.4Ghz, you are not going 50 miles on 100mw especially not since LTE is not CMDA, in the downlink LTE is OFDMA and in the uplink SC-FDMA, both of which have a much larger Peak to average ratio than spread spectrum so unless you are using an extremely narrow beam antenna (hard to aim while moving), that signal will probably be below the receiver sensitivity).
- hengheng 12y ago
  I could imagine more TX power on the balloon (nobody's in the way so it shouldn't do damage), as well as more sensitive RX antennae, since there isn't the same size or weight restriction as on an airplane or a satellite. Come to think of it, an unmanned balloon is actually the wet dream from an antenna standpoint.
  - zw123456 12y ago
    Yup. The downlink is always easy (from the tower to the phone). The uplink is always the weakest link because the size of the device, the limited battery the limited size of the antenna due to the form factor of the phone and so on. If it was strictly a broadcast solution it would be a lot easier, but even if you are streaming youtube, you still need the uplink for TCP and so on.

raldi 12y ago

> I think one problem I see with it is that ordinary smart phones won't work because they transmit at around 100mw and they won't reach that altitude, you will need an earth station From the article: "When Loon started, Google was testing a system that delivered Internet service to antennas on people’s homes. Mathe explained that this was due at least partly to technology limitations. Project Loon is now capable of sending signals that can be picked up by the smaller antennas on phones."

zw123456 12y ago
Picking up is one thing, getting the signal back from the phone with it's small antenna and low power transmitter seems problematic. But perhaps they have solved that somehow. At those distances, I am guessing the uplink would be very limited due to this. Keep in mind, that cellular carriers over time want the signal of each phone reduced. The reason is that for cellular, to get the capacity up, you want to have more cell site, each site re-uses the same spectrum of the site next to it, so if all the phones had higher power they would all be interfering with each other. They just are not designed to go those kinds of distances. Most cell radii is in the 1 - 5 mile type of range usually. Again, for capacity reasons. In the early days when there were fewer towers spaced farther apart the phones had more power (remember the old "brick phones").
- sangnoir 12y ago
  > In the early days when there were fewer towers spaced farther apart the phones had more power (remember the old "brick phones"). Citation needed. What makes you think newer phones have less transmission power than old brick phones? The working range of a cell site (the range which mobile devices connects reliably to the cell site).. is between between 50 to 70 km (30–45 miles)[1] 1. https://en.wikipedia.org/wiki/Cell_site#Range https://en.wikipedia.org/wiki/Cell_site#Range

runeks 12y ago

> I think the last time that the Loon project item was posted here a lot of the same comments were made. I think it was verified that they are flying at the 60kft - 90kft range where the winds are typically mild and in the 20mph range. From the article: "In the same time it took the Earth to complete half of its annual orbit of the sun, our record-breaker managed to circumnavigate the globe 9 times, [...] soaring to a maximum height of 21 km and drifting over more than a dozen countries across 4 continents." So the maximum altitude reached was 21 km. Also, won't increasing the antenna size on the balloon enable reception of a weaker signal? Although the antenna size increases by a factor of πd^2, where d is the distance between sender and receiver. So an antenna 80 km away needs to be 64 times larger than an antenna 10 km away in order to compensate for the weaker signal.

zw123456 12y ago
Yes, but a larger antenna will have a narrower beam width so it gets harder to aim it in the right place especially with a platform that is moving. If the antenna beam width is too narrow, you end up needing mechanically steered antennas to keep on target, which are expensive and weigh a lot. Just to level set, I am not being a negative nelly here, I think this is a super cool idea. It is just every time I read an article about it there is so little technical information that I am left with a million questions in my mind that I wonder how to solve.

tim333 12y ago

You could always use non-normal cell phones. I used a Thuraya sat phone for a while and it worked fine to a satellite 35,786 km away. Apparently the transmission power is about 2W, they cost about the same as an iPhone and weigh 140g or so. Mine worked fine off a solar panel. So these things can be dealt with, presumably more easily for a ballon 30km away than a geostationary satellite. (Here's one on amazon http://www.amazon.com/Thuraya-XT-LITE-Satellite-Phone/dp/B00RBQYO5I http://www.amazon.com/Thuraya-XT-LITE-Satellite-Phone/dp/B00... )

hobarrera 12y ago
The cost of these phones (due to lack of mass production) is probably much higher. There's also the issue of no roaming - users can't go into/out-of that region with existing devices.