The mob landed on the U.S. Capitol yesterday. Did law enforcement agencies block the signals that obstructed communications? No, the network may be overwhelmed. This is why. Yesterday’s uprising in Washington, DC highlighted the limitations of 4G technology and triggered some relatively reasonable conspiracy theories. When the mob swept the U.S. Capitol, many people nearby reported that their phones had no signal or working connection. It may be that the mob used a cell phone jammer to block most of the phone signals.
Of course, when such things happen to such incidents, it is not surprising that law enforcement agencies are interfering with communication. The answer is usually no. As our senior software and security analyst Max Eddy told me, the benefits of the police from obtaining location and messaging data are more than the benefits of cutting off the video stream.
Instead, the network may just be overwhelmed. That’s the mathematical principle there. According to radio engineer Martin Sauter, a 4G LTE cell can actually handle about 100 users. (Other similar posts on the Internet have also yielded similar results.)
A cellular base station contains several cell sectors. According to CellMapper’s data, Verizon is located close to the lawn on the west side of the Capitol, there are 12; the other two blocks to the south, there are eight blocks. Add five blocks to the north.
AT&T appears to have six locations near the Capitol, with two, three, four, five and nine cells. Cellmapper shows six T-Mobile locations, five, five, five, five, nine, and nine. I also saw seven sprint sites, each with eight, six, four, three, three, three, and three.
If you add them up, you will get 107 cells, which can feed about 10,700 people. For a few blocks, this is a huge sum! The fact that not all of these cell sectors point to the Capitol makes it difficult for me, and I have not found CellMapper’s data on the shape and orientation of cell sectors to be completely reliable. Assume that about half of these industries point to the Capitol. There are now approximately 5,000 active connections on these blocks at the same time.
I couldn’t find a good sign of how many people were outside the Capitol on Wednesday, but of course not only members of the mob, but also the media, police, passers-by, staff, and even the people running the small merchandise stalls I saw on Twitter . According to Google, the floor of the Capitol is approximately 1,600 feet by 700 feet. So it is approximately 1.12 million square feet.
For a relatively tight crowd, 16 square feet per person, theoretically, you can accommodate 70,000 people on the grounds of the Capitol. I am not saying that there are 70,000 people there, how many people can fit in the room. But let us now say that one-fifth of these theorists try to use mobile phones. We have 14,000 concurrent connections. Therefore, in extreme cases, it will be relatively easy to overload the cellular network.
The police’s phones continue to work because they are located in a special part of the AT&T network called FirstNet, which prioritizes first responders. However, since FirstNet ranks first, heavy use of FirstNet will slightly reduce the capacity of civilian equipment in this location.
Why hasn’t this happened in other major protests in the National Mall? For most events, the carrier rolls a series of truck-based cell locations onto the streets around the shopping center (or events in general). Often referred to as COW (battery on wheels) or COLT (battery on light trucks), they are designed to divide larger batteries into smaller batteries to accommodate more people.
On a normal tourist day, cellular systems in buildings such as office buildings and the Smithsonian Museum also provide services to many people. These systems can reduce the burden on the outdoor network. Due to lack of planning or fear of violence, the haulers did not seem to have driven those trucks yesterday. (Given that these mob members destroyed the radios of CNN and other organizations, and that conspiracy theories like QAnon tend to overlap with anti-5G conspiracy theories, this concern would have been justified.)