Telecom Informer

    

by The Prophet

Hello, and greetings from the Central Office!

Summer has arrived in the Pacific Northwest, a place where I have landed once again after a busy spring ping-ponging between Europe and the U.S.  I am actually back in my old Central Office, covering a vacation for the new operator, and being back here reminds me of what my life used to be.  It's like wearing a pair of old shoes.  The highlight of my spring was the Turkmenistan Pavilion at Milan Expo, where the reclusive country showcased its communications satellite technology.  The world is becoming an increasingly connected place and it's really amazing to see first-hand how much development has occurred in such a short time, bringing the world ever closer.

That being said, there are still very large parts of the world that have no connectivity whatsoever.  My home state of Washington is one such place.  Fully one third of the state is federal land, most of which is rugged terrain without any coverage at all.  Given the northerly latitude and mountainous terrain, portable satellite phones offer questionable reliability.  So when you really need connectivity, your options are pretty limited.  Portable satellite phones aren't always practical and, of course, the cost is prohibitive.  If you needed a "plug and play" connectivity solution that works with a large number of standard mobile phones in very remote areas where regular road access isn't possible, you used to be out of luck.

These days, however, you can use Remote Mobility Zone (RMZ) equipment, and a TV series called Capture made some of the most creative use of this that I have recently seen.

My friend Barkode (Matt Lewis) produces a bunch of crazy technology for movies and television shows (along with actually producing movies and television shows) and his team built the technology behind Capture, a TV show that essentially showed a high-tech game of hide-and-seek.  This show was filmed in a remote forested region of northern California.  The terrain was similar to my home state of Washington and, being public land, the cellular coverage was very limited.

Actually, there was spotty coverage in only a remote corner of the property.  The premise of the show was an elaborate game of hide-and-seek, completed over several days with the participants fed a strictly controlled and limited diet.  The technology used to enable the game was built on Google Nexus phones, which communicated with centralized servers.

To run the game, the phones didn't need high bandwidth (video and other high bandwidth content was preloaded on the devices), but they did need constant, low-latency connectivity.  This is because the game was designed where certain events would be triggered based on the activities of the players on the ground, or the directives of the show's producers.

Given the real-time nature of the game, there weren't any second shots.  Everything had to work correctly the first time or the scene might be lost (making the players very unhappy - they were competing for $250,000).  This meant that communications needed to be reliable and the network needed to be highly redundant.

How complicated could this be?

The part that was on the Internet wasn't particularly complicated; servers were placed in three separate locations and the network topology was built in a fail-over configuration.  However, covering the playing field was considerably more difficult.  This required creating perfect wireless coverage in the middle of a forest with no electricity or mobile phone coverage.

Wi-Fi, obviously, would be out of the question for entirely covering such a large area.  The solution?  AT&T Remote Mobility Zone (RMZ) units.  These operate as a miniature cell tower, are small enough to fit in a suitcase, and provide backhaul to the AT&T Mobility network via either satellite or terrestrial radio.

The first problem encountered with these units was that the coverage area they provided was very limited.  Also, trees scatter cellular signals, they skip over water (part of the playing field included a lake), and interference from neighboring cellular systems can be a problem.  It quickly became evident that this wasn't going to be a simple deployment.

The originally specified deployment simply wasn't adequate for the terrain; there wasn't enough equipment.  Somewhere along the line, and well before Barkode got involved, the calculations missed the fact that the terrain was rugged, mountainous, and covered with trees.  Also, there wasn't any single logical highest point that could cover all of the playing field.

So, in order to get above the tree line and prevent the signal from scattering as much, RMZ units were mounted on top of scissor lifts, and the locations were strategically selected for maximum coverage.  Many more were used than originally specified.  Powering the units was also a challenge because there wasn't any utility power.  For this, a combination of solar power stations and small gasoline generators was used.

Unfortunately, there was a local AT&T tower that kept interfering with the deployment in one corner of the property, and it drove the team completely nuts with troubleshooting.  This is because the Google Nexus handsets (equipped with AT&T SIM cards) would keep switching over to this tower instead of the better RMZ coverage.

Why?

The RMZs are configured as a network called "ARMZ."  This means there is a different Mobile Country Code (MCC) and Mobile Network Codes (MNC) versus AT&T Mobility's usual network, so if the handset isn't loaded with AT&T firmware, the phone thinks it is roaming.  And naturally, Google Nexus devices aren't natively supported by AT&T, so they don't have AT&T firmware.

In practice, this meant that whenever someone was in the corner of the property with a shred of AT&T signal, the handset would re-home onto the primary AT&T network, rather than the portable one Barkode's team had deployed.  This obviously wasn't going to work, because the time required to do this introduced considerable latency, particularly as handsets "ping-ponged" back and forth between networks.

The ultimate solution?

Persuade the phones they weren't roaming, and prioritize the ARMZ network above the AT&T network.  This was eventually accomplished through a feature called Enhanced Network Selection (ENS), which is an advanced GSM feature.  Few carriers use it, but AT&T supports it and in this case - with a lot of tweaking to the Android firmware and some, erm..., highly questionable network tweaks - it eventually worked.

With that problem solved, there were still coverage gaps in the network.

Remember, in order for the game to work (think of it as a game of hide-and-seek played out over several square miles), there had to be completely reliable coverage and it had to cover the entire playing field, an area of several square miles with trees, hills, rocks, a river, a lake, and more.  This is surprisingly difficult to do.

Fortunately, the phones were equipped with a full mobile data stack (using GPRS, which the RMZs support), a voice stack (including SMS), and Wi-Fi.  Barkode's team designed the software to use all possible ways to communicate, so if one method failed to get through, there was another option.  This made it possible to plug the gaps with Wi-Fi.

How?

By literally strapping wireless access points to trees, and using fiber (originally installed to run the cameras) for backhaul.

Capture ran for only one season.  The technology worked surprisingly well for the entire month that the show was filmed, but ultimately, the story wasn't interesting enough to viewers.

In the end, the network was torn down and the forest was restored to its prior state, as if nothing had ever happened.  And with that, I will leave you to enjoy your summer.

Get out, enjoy a music festival, and come up with creative ways to communicate that aren't on a mobile phone!

References
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