Cellphone Surveillance Techniques and TV's 24

by Sarah Cortes

Thanks to the TV show 24, cellphone triangulation is now a household term. When you want to find the bad guy, or save your friend, you just triangulate. Like, on your laptop. It seems. According to the show.

So cool.

The flip side, that's not so cool, is that it provides yet another way to invade privacy and control innocent people and even, in the wrong hands, make their lives miserable. For example, police have found human traffickers use this technology around the world, including here in Boston, to to keep women forced into sexual trafficking from escaping their sad and all-too-common plight, while claiming that "they are not prisoners, they are free to come and go."

Of course, back in the unrealistically black-and-white world of 24, everyone knows who the good and bad guys are. And everyone knows that when you want to triangulate on 24, you call not for Jack Bauer, the ostensible hero. Nope, when it comes to the hard-core tech stuff you call for - Chloe, the straight-talking, rocking techno chick. You go, girl!

In real life, locating people using their cellphones involves multiple technical options. Cellphone "triangulation" is just one of several available techniques. LBS, or Location-Based Systems, fall under one of three categories:
•Network -based (of which triangulation is one approach)
•Handset-based (GPS)
•Hybrid

Network -based Cellphone "triangulation" is a technique that falls under the "network-based" category. It is considered the most accurate of all methods. But you might want to think twice if you're Jack Bauer and you need a helicopter to drop you an escape ladder into a precise location - because triangulation is also one of the most challenging techniques. Like landing a drop shot from the back of the squash court, it requires hours of practice and has a lower percentage of success. But when it works, it's sweet.

In general, network-based LBS utilizes a service provider's network infrastructure to identify handset location. The advantages is that it can be implemented non-intrusively, without affecting the handset. The disadvantage is that you have to ask the carrier to provide you the data based on a signal in relation to its towers.

Handset-based On the other hand, handset-based LBS requires installation of client software (GPS) on the handset. The advantage is that you don't need to ask carriers for tower information. But you still need to be able to read GPS, or request reading from GoogleMaps or an application that does.

Here's how handset-based LBS works:
•First, it calculates:
1) Location by cell identification
2) Signal strengths of the home and neighboring cells; or
3) latitude and longitude, if the handset is equipped with a GPS module
• The calculation is then sent from the handset to a location server like GoogleMaps.

Network-based LBS Challenges:
• Accuracy varies. Cell identification is the least accurate, triangulation, the most accurate
• Accuracy is closely dependent on concentration of base station cells, with urban environments achieving highest accuracy
• Requires working closely with service provider because it entails the installation of hardware and software within the operator's infrastructure.
•A legislative framework, such as E911 is required to compel service providers to cooperate and to safeguard privacy

Handset-based LBS Challenges:
These center around the necessity of installing software on the handset, which:
• Requires the active cooperation of subscriber
• Requires software that can handle the different handset operating systems
• Typically, only smart phones, such as Symbian or Windows Mobile are capable
• Proposed work-around: manufacturer installs embedded hw/sw on handset

These issues are coming up more frequently these days with the advent of a plethora of Privacy Laws. Understanding them can help avoid trouble for your organization and in your personal life. And., like Jack and Chloe, it makes you --so cool.

copyright 2009 Sarah Cortes

You can read Sarah's other tech columns at IT Knowledge Exchange