It is now an urban legend that SMS is transmitted in overhead. In UMTS, a separate connection is set up to transmit the message and acknowledge receipt.

You're correct, only that carrier's customers (and supported MVNOs) would be able to use that tower on a truck.

This event is an excellent candidate for a temporary cellular deployment, engineered and operated by a carrier. Typically, they will not charge for the service because of the extra call revenue and to avoid bad publicity from poor coverage or capacity. Unfortunately, you would need to engage both Verizon and AT&T to provide service for their own customers.

I recommend not deploying a cellular repeater in this case because there is likely insufficient isolation between the surrounding macro network and your event site. Without sufficient isolation, the repeater will impair the operation of the host base station and not even provide significant coverage improvement due to massive multipath problems. If you're interested in a survey, you could use an Android phone with RF Signal Tracker and record the RSCP and Ec/Io of UMTS ("3G") service.

If the carriers are not interested, I recommend deploying your own Wi-Fi network. I cannot offer advice on how many access points you would need, but it will be many. Because Wi-Fi was never meant to be infrastructure and lacks features like uplink scheduling and handover, controlling the footprint of each access point is very important.

In some areas, Google Maps already provides multi-modal trip planning on public transportation, as long as those modes fall into that category. But it doesn't work very well. I can ask for driving directions between a city and an island which will include the ferry, but asking for public transit directions between the same two points routes me on Amtrak several hundred miles south, then various bus connections to ferries servicing various small islands before reaching a completely different ferry than the first mentioned one. Total time over twelve hours when the direct route on public transportation is about four. Clearly, their algorithms need improvement.

Terahertz radiation does not cause cancer. I recently completed a masters degree studying terahertz waves. You may be confusing the terahertz scanners with the X-ray scanners, which DO cause cancer.

This is a great post. I was not aware that FELs are only spatially coherent due to bunching. I was under the impression they were also temporally coherent.

One of the main advantages of IPv6 is we will be able to abolish NAT (for security, transparency, and reliability), yet you propose we adopt IPv6 and issue all Internet users with an... address translation device? Why not advocate keeping IPv4 then?