First responders need access to life-saving, 3D location technology

By Charles Werner and Eddie Reyes

The FirstNet RFP has been issued, responses are back and evaluations are currently in progress. For all practical purposes, the nation will finally get a broadband network dedicated to Public Safety needs. The question is: What we will get in the public-safety broadband network that is useful to us?

To get an idea, we looked at the 16 objectives that FirstNet has laid out for the network. A key one we quickly gravitated to is the need to provide precise first-responder location accountability indoors and outdoors. Second to mission-critical voice, there is not another application that is more critical, answering two important questions: Where are my people in an incident, and where is the “incident”? Getting accurate and precise information will allow optimal dispatch of our men and women correctly, meaning a faster response; use of strategies that keep them from harm’s way while also using resources more efficiently—an important consideration, given ever-shrinking budgets.

So, what is required for any location system to satisfy a "mission critical" need?

• The location system needs to be highly accurate XY information, both indoors and outdoors;
• Indoors, it should provide near-floor-level vertical information (particularly for high-rise buildings in New York, Chicago, and Los Angeles), also known as the Z-axis;
• It needs to work reliably and consistently, even during storms and adverse conditions;
• It needs to work pervasively throughout a city, because emergencies can happen anywhere;
• It needs to support the public-safety application, such as 3D geolocation, navigation and Blue Force Tracking;and
• It needs to transition seamlessly between cellular, Wi-Fi and satellite communications, always operating on the technology with best signal strength at a given moment.

In fact, Public Safety Communications Research (PSCR) has done extensive work in this area and identified candidate location technologies (Location-Based Services R&D Roadmap, May 2015). Some would qualify for mission-critical operations, whereas others we don’t see playing that role. The technologies identified are:

• GPS/GNSS;
• Cellular-based systems such as Observed Time Difference of Arrival (OTDOA);
• Short Range, such as RFID, wireless personal-area networks (WPAN), wireless local area networks (WLAN), ultrawideband (UWB) and Wi-Fi; and
• Terrestrial Beacons, such as the metropolitan beacon system (MBS).

There is no doubt that GPS will continue to be the foundation on which geolocation is provided. It is a robust global system, designed specifically for mission-critical mobile applications. However, GPS does not work indoors or in urban areas where a device cannot see four or more Satellites to determine your location. It also has other constraints, such as it can cause a device to consuming lots of power and is susceptible to jamming. So, the central question is: What technologies complement GPS to fill the holes that GPS leaves in the urban areas?

Cellular-based systems such as OTDOA are terrestrial and leverage the cellular infrastructure, which is advantageous since it is already present in the network and FirstNet devices will be LTE-based. However, those characteristics also make it significantly less accurate than other approaches.

This disconnect occurs because the cellular system is not designed for location but rather is designed for voice and data applications. In a cellular system, all that is required is a signal from a single cell site to carry voice and data; in a location system, a device has to see four sites in a square configuration to get good location This ideal cell-site placement happens occasionally, but often it does not—hence the accuracy of cellular-based systems has been in the hundreds of meters, not in the tens of meters required for robust location accuracy.

Accuracy also suffers from the fact that there is no ‘floor’ level information available, nor the ability to navigate with such a system. There is a reason why the U.S. Department of Defense (DoD) built its own dedicated system for location—GPS—and did not try to piggyback on a commercial satellite system.