In what world is 50 Volts/meter typical of any user near a cell site? If Typical sector antennas have 20 dB gain, and I'm not sure they are this high for 120 degree sectors probably only 14 dB, at 20 watts average transmitter power one has to be within about 5 meters to see that sort of field strength. At 50 meters with inverse-square (far field) this falls to one hundredth that level. Who spends significant time only 5 meters from the center of beam of a cell antenna? I suspect that field strength from a leaky microwave oven far surpasses typical exposures from cell sites. I think this report is BS on multiple counts.

A single satellite can easily have much more capacity than a 10 Mb Ethernet cable. Today's point-point IP radios can easily do 100 times that but a satellite's capacity is spread over a very large area. It doesn't solve the problem if you use beam forming. To cover the whole earth with N satellites, each satellite's available RF power must on average illuminate earth_area/N. That sets the best case power density with perfect patterns. In actuality it will be worse than this. On the ground, each user can not have an arbitrarily large/directional antenna. The mobile phone user wants the radio and antenna to fit in his/her pocket and run from batteries for a day. Thus both signal power, S, and noise spectral density, N, are set. Per Shannon, this establishes a maximum average data rate per user. This is not a technology problem in that Shannon tells you what the limit is if you do it perfectly. The only way to improve this link budget which is dictating the maximum average data rate is to add more antenna, more aperture, at the user's end and must always be low enough directivity, well formed/pointed/steered for satellite handoff. Directive antennas are inherently larger. And though they can be steered, nothing else substitutes for aperture - how big a 'bucket' to 'catch' RF they represent - which is necessary to increase S. With set ERP at the satellite the required aperture is independent of wavelength. A LEO network *is* possible but the average per-user data rate is set by physics. I maintain that in today's market, which has an expectation of ten's of Mbps (or something similar) that the attendant per-user cost will not support the expectation. The Iridium network with (actually less than) 77 satellites was severely over subscribed. Each user could pay a lot to get a few kbps for a few minutes each day but all users could not simultaneously get many Mbps or even two way audio all the time. A few users in extreme situations were willing to pay the fee but the average user over the whole world would not be willing today. It's physics and economics. But this doesn't keep people from investing, witness Iridium.

Do the math. First make an estimate of how much solar power your 300 (or whatever number of) satellites can catch. Then multiply that by the conversion to RF power and spread the resulting power evenly over the surface of the earth. You now have power density. Next, calculate the maximum antenna size/directivity a single user can use. His beamwidth can't be narrower than the inter-satellite angular spacing. Next after derating the above result based on necessary link margin for foliage, precipitation loss (if it applies at the wavelength used) etc, apply Shannon's equation to this power budget and calculate the available per-user information rate. Finally ask yourself who besides the fringe will be willing to pay enough for this relatively low average rate to support the whole thing. As with the Iridium system, even without latency and particularly in the present age with the per-user bar up in the 10's of Mbps, the overall user base will not be willing to pay so much for so little. For a few users the few kbps (not Mbps) average rate might be useful but it is necessary to have a lot of users to pay for it all. This is essentially a very over-subscribed approach and the physics, even with moderately good nearly line-of-sight radio paths, won't support any reasonable economic model. The US 7B original cost of Iridium turned into something only a few tenths of a percent of that at the last sale, as I understand it. Yes, it is possible to make a system that can support a few users at high rates or a lot of users at low average rates but the economics require both simultaneously. It's not going to happen with a LEO satellite system in this day and age.

ERP is Effective Radiated Power. In the direction of maximum beam of my laser pointer, I get a spot on the order of 1 " in diameter 200' away. This means that most of the 5 milliwatts the laser puts out is contained in a spot of on the order of one square inch. This intensity is brought about by the columnation or directivity of the laser itself. It's a puny 5 milliwatt transmitter with a high gain antenna. In order to get the same intensity from an isotropic antenna (one that spews equally in all directions) rather than a directive one, I'd need to increase the power by the ratio of 4*PI*(200 feet*12 inches/foot) ^2. That's how many square inches are in a sphere with radius 200'. That's almost 80 dB (a hundred million times) change of directivity. BTW directivity is the same as antenna gain if the antenna is well matched and not lossy. 80 dB above 7 dBm ( 5 mW) is +87 dBm or +57 dBW That's HALF A MILLION watts! But this is not "cooking power". Energy is conserved, it's still only a 5 milliwatt, Class III laser and this ERP number is only a measure of what transmit power would be necessary if there weren't any antenna gain. All this alarm about ERP is about not understanding what the terms mean. ERP is transmitter power + antenna gain, not real power. The actual transmitter is something like 24 watts, roughly the same as one segment antenna of a cell site. The system has high ERP because it's at millimeter where the antenna has a lot of gain. This whole thread is alarm about nothing...

In spite of all the bad press *freespace* wireless isn't as terrible as you think. See http://www.corridorsystems.com... and in particular slide 16. The problem is that we live in a world with anything but freespace paths (truly laser light line-of-sight). The difference can be a factor of a million to 1 (60 dB)in throughput over common paths. Your cell phone could talk to another one 2000 miles away if you had free space but sometimes you can't get to a tower 2 miles away. Thus, this really is a problem Shannon's equation can apply to. Wireless for 3g,4g,5g only works when the paths are *really* short - like a few tens of meters. See the rest of the paper.

Start at the building tops - cell sites already do. The issue is to get very close to LOS to the user base so that that data vs. energy is maximized. Take a look at COST231/Hata or similar real-world RF pathloss models. Anything other than LOS is a killer and can't be afforded. The present flooding model for cellular architecture is inherently broken. Montana|Idaho|etc never will get full coverage highspeed data, the present approach doesn't scale. Going too far/high doesn't work either. Satellite distribution (from Iridium to geosynchronous and beyond) doesn't work either. Has to server too many users/needs to much devoted energy/user. Has to be lots of points of presence, LOS and close to end users.

I think he is on to something but the path lengths are too long. Presuming the market will stand for nothing less than mobility and at least 4G class data rates, physics requires that radio paths be shorter than he conjectures. Here's why: Mobility means the user device must be powered from batteries and fit in your pocket. It must contain its own antenna. Thus there is a maximum local_storage/delivered_bit ratio available. It costs battery power to deliver a bit of information. Non-line-of-sight paths are entirely too wasteful - witness a cellphone "handy-talky" that can communicate 2000 miles in truly free space not making it into a cell site only 2 miles away in real world conditions. Wireless goes as inverse-square so that's a million-to-one loss, 60 dB. Given one has to use truly LOS (as in laser light), the question of radio path length is answered by looking at the aperture of the antenna in the user's device. It can be thought of as a "bucket" that catches whatever falls on it. The size of the bucket is roughly the physical size of the device. While as frequency goes up (shorter wavelength) antenna gain goes up, so does path loss. The device can only catch as much flux as is falling on it. This is like solar panels - sunlight is about 1 kW/m^2 on earth- try as you might you won't get more energy per unit capture area. If one does the link analysis and applies Shannon's equation, the ONLY solution that works requires paths of, perhaps, a few hundred meters. For this reason, the drones need to be quite low and there need to be more of them. It turns out that this is possible if they are tethered and powered from the ground. http://www.sonic.net/~n6gn/SWT... gives an example of a way to do this while also allowing the (heavy) network hardware to stay on the ground. Demo coming soon. n6gn

I agree. Got to a WebSDR like http://websdr.ewi.utwente.nl:8901/ and automate the process. You can get a large amount of OTA signals to examine, in the correct ratios, styles and weightings. This requires you to decide whether or not the signal under test is CW or not but that's part of your algorithm anyway. n6gn

I note that the OPERA report (Open PLC European Research Alliance, Document OP_WP1_D5_v0.9.doc) indicated a lot less than 200 Mbps of information capacity on typical European systems.A better guess seems to be 20Mbps on a good day. Thus, with your estimations, more like 50 kbps per home with conventional BPL/PLC techniques (below 80 MHz) seems likely. All the more reason to move it to microwave-over-powerline. n6gn

Don't confuse the user connection with the 'backhaul' which is the over-power-line part. However, also don't confuse 200 Mbps on a lab bench with a lot less than that over a single hop on real lines having excess noise, attenuation. The 200 Mbps hardware may only need 20 MHz of spectrum in the 4-80 MHz region to support that raw rate but after a few links are chained together throughput will likely be a LOT lower than that. Now aggregate 1000 homes onto that backhaul and you may scarcely have enough performance. Fortunately, the smart-meter requirements for average data rate and latency are probably very small so it might all work fine - except for the ingress/egress radiation problems from the line which could be a show stopper. Too bad they don't move it all up to microwave-over-power-line and avoid the interference problem at the same time they get 10X or more capacity improvement. disclaimer: I resemble the above remark. n6gn

Consider 77 satellites, each catching [100 watts] of solar power that you perfectly turn into useful, information carrying RF, and then perfectly overlay so that the entire surface of the earth is covered. That sets available flux at ground level, You can't use more gain and not lose coverage area (location independent access). Now add users with omni-directional antennas. User antennas must not only be small but generally omni-directional - they have to see all the sky and can't be high gain beams constantly pointed (too big, too expensive). The associated antenna aperture determines captured power. Because of system noise temperature (antenna sees terra firma no matter what NF the equipment has, S/N ratio is determined, thus due Shannon capacity of link is set. Guess what, it's not much to write home about if you plug in reasonable numbers. A few users on each satellite can get a little bit but all users can't use it all (or much) of the time. And we haven't even talked about backhaul, real-world efficiences etc. This problem is akin to the problem of getting 3G or 4G mobile networks to work everywhere. They don't and won't unless the paths are shortened greatly and the density of points-of-presence (cell sites) is greatly increased. n6gn

http://www.sonic.net/~n6gn/ocar/ocar.html This is essentially what one does with after market cellphone amplifiers, but the link offers more detail of the theory and what it takes to operate them properly. These amplifiers are bi-directional, both uplink and downlink are supported but in opposite directions. Use two isolated antennas and make the one pointed at the cell site (particularly) as directional as possible. I suggest a $50/$75 3' parabolic 'grid' reflector for PCS/850 MHz respectively. The ones offered for WiFi (2.4 GHz) actually work very well on PCS but not at 850 MHz and offer ~24 dBi gain. If you are really cheap, build corner reflectors http://www.sonic.net/~n6gn/corner.pdf.

We hear with our brains as much as with our ears. Simply buying hardware to compensate for the roll-off is NOT the solution. Hearing is tremendously adaptive and interactive. When you buy HAs from a reputable source you are actually buying a lot of visits for measurement/modification to allow you to adapt to the augmentation as well as possible. This is unique to each individual. This easily adds up to MANY (10-20/year) office visits over the life of the device(s). I too used to think that simply measuring the roll-off and applying compensation was a solution. It emphatically is NOT. Before you all attribute the cost of the hardware to greed, take a look at the service and also look around and find evidence of overly-fat audiologists. I don't find them around where I live... n6gn