Network-based tracking, an alternative to GPS

Published 3 May 2011

With improvements in network-based tracking police and first responders now have a reliable alternative to GPS tracking when searching for suspects or responding to 9-1-1 emergencies; using signals from cell phone towers to triangulate a phone’s location, network-based tracking has steadily improved and in some regards surpassed GPS-tracking; unlike GPS-tracking, network-based solutions cannot be jammed by a user and law enforcement officers do not need to carry any additional equipment; with network-based tracking police can find an individual’s position within fifty meters using data from cell phone towers; despite improvements in network-based tracking, the system is not perfect and GPS still has many strengths

With improvements in network-based tracking police and first responders now have a reliable alternative to GPS tracking when searching for suspects or responding to 9-1-1 emergencies.

Using signals from cell phone towers to triangulate a phone’s location, network-based tracking has steadily improved and in some regards surpassed GPS-tracking.

Unlike GPS-tracking, network-based solutions cannot be jammed by a user and law enforcement officers do not need to carry any additional equipment.

Marty Feuerstein, chief technology officer of Polaris Wireless, a network-based tracking technology firm, said, “The feedback I get from law enforcement agencies said that GPS doesn’t solve the problems they have. A lot of [officers] tell me that it’s easy for users to disable GPS, you can jam it [and] there are battery life implications.”

With Polaris Wireless’ Wireless Location Signatures (WLS) technology police can find an individual’s position within fifty meters using data from cell phone towers.

To pinpoint a cell phone’s location, WLS technology measures the signal strength and delay times of a specific device in relation to the cell towers around it. That information is then relayed to a base station which houses software that automatically plots the data against a radio environment map to give the location of an individual holding the specified phone.

Despite improvements in network-based tracking, the system is not perfect and GPS still has many strengths.

Jeff Kagan, a telecommunications industry analyst, explains, “For GPS, you need to see the sky, whereas with wireless you don’t. But GPS can get you very, very close. Which one is better? I don’t really think we can say, but ultimately, law enforcement should have both.”

For instance in urban areas where cell phone towers are more densely clustered, network-based tracking is highly accurate and if an individual is inside a large building the phone may not be traceable with GPS.

Kagan said, “You still have to triangulate between cell towers,” but, “The more towers you have, the more accurate it will be.”

Therefore in suburban and rural environments with few cell phone towers, network-based tracking solutions are not as accurate, generally pinpointing an individual within 100 meters on average, making GPS a popular option in these settings.

Both tracking methods suffer from the inability to track an individual’s location vertically. In large urban environments if an individual’s location is traced to a large fifty-story building, first responders can have a difficult time in narrowing down where that person is.

To address this problem and enhance accuracy, Polaris Wireless is developing the technology to pinpoint an individual’s location vertically. So far the company has been able to narrow down a cell phone’s location to within a few floors.

“In general, we can get within five floors,” Feuerstein said, regarding the vertical tracking technology under development. “It’s hard to get down to floor-level reliability. It’s one thing to do location if you are on the ground or the first few floors. But it’s much more of a challenge if you are in a penthouse of a 50-story building.”

Feuerstein expects the technology to be ready for release by the end of 2011.