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Tech Forecast

Why Your Phone Doesn't Work During Disasters—And How To Fix It

When terrorists attack, mobile phone networks fail. They also go down during natural disasters, and even at big sporting events. Here's what causes network overload and what we can do about it.

When two IEDs went off at the Boston Marathon's finish line on Monday, mobile phone carriers were overloaded.

In the fog of disaster, hundreds of thousands of people worldwide tried calling their loved ones in the Boston area. The Boston metropolitan area's robust mobile networks simply clogged up as Verizon, AT&T, Sprint, T-Mobile, and other providers coped with a massive and unexpected surge. In the aftermath of natural disasters, terrorist attacks, and anomalous incidents worldwide, telecommunications networks simply can't cope with the sharp increase in call volume. Can that be fixed?

On Monday, mobile providers scrambled to cope with the unexpected call volume increase and to urge users not to make voice calls. For example, Verizon issued a terse statement saying they were "enhancing network voice capacity to enable additional calling in the Copley Square area of Boston. Customers are advised to use text or email to free up voice capacity for public safety officials at the scene."

In an email to Fast Company, Thomas Pica, Verizon's executive director of corporate communications, said that although Verizon "has a significant amount of margin in (their) system," significant events could exceed local capacity at individual cells. In addition, when sudden disasters such as the Boston attack do happen, engineers at mobile providers can monitor and adjust network elements in real time.

Users of every major mobile carrier reported outages in the Boston metropolitan area. This lead to the spreading of unconfirmed rumors which were taken as facts by the media, such as the Associated Press incorrectly reporting that mobile service had been shut off in Boston to prevent remote detonation of bombs with mobile phone times. A law enforcement official told the AP that a shutdown was taking place.

What did happen in Boston, however, was a routine swamping of mobile networks that takes place whenever an anomaly incident occurs. Shortly after hurricane Sandy, (now former) FCC chairman Julius Genachowski warned that mobile service was devastated by the storm. Although Sandy involved a physical destruction of mobile network infrastructure that was very different from the simple heightened call volume of Boston or the 2007 San Francisco earthquake, the basic elements are the same.

Mobile networks have bandwidth that is more than sufficient 99% of the time. However, when disaster strikes, the decentralized nature of the network means that whole geographic regions can be knocked out by increased call volume. Whenever the generous-but-finite bandwidth at carrier site buildings are strained, users are prevented from making voice calls. Because SMS text messages take up far less bandwidth, mobile carriers instead encourage users to text message each other. As Pica put it to Fast Company, "text requires less dedicated real-time capacity than voice. Data networks including LTE and EVDO were not impacted due to the nature of the way data systems are used."

During disasters, all of America's mobile carriers jump into action to mitigate service outages and, if needed, temporarily boost service. AT&T spokesperson Fletcher Cook told Fast Company that the carrier has more than 320 equipment trailers and support vehicles that can be deployed nationwide in case of disaster. As Cook put it, AT&T's goal during emergencies is to " route non-involved telecommunications traffic around an affected area, give the affected area communications access to the rest of the world, and to recover communications service to a normal condition as quickly as possible through restoration and repair."

It is possible to build redundancies into America's mobile phone infrastructure which would allow the easy placement of phone calls during crises. This would, however, be massively expensive and carriers would likely pass the cost onto customers. In a 2007 Computerworld article, reporter Todd R. Weiss discovered that adding regional redundancies to mobile phone networks is not economically feasible. However, mobile providers can temporarily boost coverage in areas where they anticipate trouble such as football games and music festivals. They can even take away mobile coverage—San Francisco public transit provider BART famously had carriers block wireless signals in order to prevent demonstrators from organizing after a homeless and mentally ill man was shot by BART police.

With that in mind, a series of new and innovative methods have been created to temporarily increase bandwidth during times of emergency. These range from mobile emergency wireless trucks to crowdsourced casualty clearing houses to creative bandwidth reallocation.

Two engineers at AT&T, Bob Mathews and Gary Chow, have devised a method of temporarily boosting mobile phone capacity at sporting events and concerts. AT&T's multi-beam antenna uses a special setup of narrow beams spaced 20 degrees apart, mounted at special events, to boost network traffic capacity up to 500% in order to deal with large crowds. The multi-beam antenna has already been tested at the San Diego Comic-Con, Coachella, and the Super Bowl. The pair helped develop the antenna in response to what they saw as a "telecom Moore's law," wherein data traffic consumption regularly doubled every two years.

Patrick Meier, a crisis early warning and humanitarian response expert at the Qatar Foundation, said that the Boston attack was indicative of a need for a new system which he calls a "Match.com for disaster response." Meier is currently working on a similar project at the Qatar Foundation to match local needs with publicly available information through a low-bandwidth database that combines crowdsourcing, microtasking, natural language processing, and machine learning to provide instant disaster relief information. In the case of Boston, a database accessible to anyone looking for information on a loved one or a runner stranded outside their hotel could quickly leave a message or find a place to stay.

Lastly, a quixotic attempt to boost Wi-Fi bandwidth could create a viable backup communications system during natural disasters or terrorist attacks. Globalstar, a relatively small satellite company, is attempting to convince the FCC to license their communications spectrum for Wi-Fi use. This can be done because Globalstar's allocated spectrum is right next to the spectrum bandwidth allocated for Wi-Fi use; if the FCC gave their approval, routers would be able to use Globalstar's spectrum through a simple software update. Globalstar has the option, if this project is approved, of jointly sharing the spectrum with multiple wireless providers or licensing it exclusively to one lucky carrier. By significantly increasing the bandwidth dedicated to Wi-Fi, users in public areas or crowded environments would enjoy much faster wireless Internet speeds on their mobile phones and tablets.

Additional reporting contributed by Ben Paynter.

[Image: Flickr user lragerich]

This story has been updated to include additional comment from AT&T.