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Posted on April 26, 2018 by West Corporation 


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Q&A: The Revolution of Wireless 911 Location Technologies

By John Snapp, VP of Technology

Earlier this month, I presented to carriers and PSAPs about new solutions that promise a better location earlier in the 9-1-1 call flow. I also spoke about the methodology and results from West’s location testing and trials with Google’s Android-based ELS (handset-initiated location).

The following addresses the questions I wasn’t able to respond to during the live event.

Q: We received many similar questions around the timing and availability of the wireless 9-1-1 location technologies discussed. Many asked, when will these solutions be made available? How soon will PSAPs start to benefit from the improved location? What are the potential implementation impacts to carriers and PSAPs?

A: West’s WDLS is a carrier-based solution available today for implementation—it requires only initial testing and set up. Carriers interested in learning more about WDLS should reach out to their account representative.

Timelines and schedules are determined by the carriers—and several carriers have already begun the process for testing and deployment.

No changes in equipment or architecture are required by the PSAP. PSAPs that are NG9-1-1-capable will also be able to benefit from location update pushes.

PSAPs interested in learning more about when the improved location will be available in their jurisdictions should contact their carrier representatives directly. If needed, we are able to turn on the location functionality on per PSAP and by carrier.

Q: Do we, as a carrier, have to do anything to get these location improvements from Google ELS, LaaSer, AML, etc.? Is there some sort of network-level implementation that needs to be done on our end?

A: These locations can be provided through the GMLC or MPC within your existing network. You will only need to work with West.

Testing and WDLS Functionality

Q: Did you use just one carrier to do this testing or both TDMA and CDMA? Which carrier did you find more accurate in this testing CDMA or TDMA? Did that have an impact on testing?

A: We used multiple carriers but aggregated the data so we could calculate an average (versus focusing on any one carrier). The purpose of the trial was to measure the ELS technology.

Q: Where does West get their proximity data?

A: There are three possible sources for proximity data:

  • Subscriber billing address or other subscriber-provided address through provisioning WiFi calling or a femtocell with their carrier
  • Subscriber provided address using an app where they provision addresses associated with their phone number
  • Publicly-available data such as county records

Q: What methodologies do you propose for determining the best “single” location when two data elements do not overlap or are not within the same proximity?

A: We assign trust factors to the different location technologies. The cell ID receives the highest trust level because it can’t be spoofed. If a location appears impossible based on the cell ID or other high trust data, we filter it out and provide the other locations.

Q: What is crowdsourcing?

A: Crowdsourcing is the ability to utilize multiple beacons or other data points to calculate location i.e., multiple WiFi hotspots that are visible around your phone that can better triangulate your location.

Q: Can you explain how/why you determined to send the location that was on land versus the location out in the ocean?

A: We look at the different locations to make sure they are all subsets of other locations received for that call. If they are not, we look at the trust factors of the different locations to filter out potentially false data. For example, the water location did not fall within the cell site coverage area so it was eliminated.

Q: You mentioned crowd sourcing WiFi and cell site info. What is the source of this? Is it open source, who is crowd sourcing this data and is it trustworthy?

A: Mobile devices that are using location services (where users have not opted out) provide anonymous location measurements to Google or Apple, who build the location sources around a handset. These are anonymous and encrypted but can be used to quickly triangulate a handset location, even if GPS is not available. Because there are so many different devices contributing to the data pool, we consider it very reliable.

There can be an issue with crowdsourced data if an access point is moved. However, in those instances we would validate against other data points and filter out the potentially false location.

Q: Did you test with location services turned on and turned off on the phone and were there differences?

We did not see any differences.

Q: Would the LaaSer location provided in Samsung have any other advantage over ELS or Apple AML? If they provide or turn on AML/ELS, what is the reason to use LaaSer?

A: The LaaSer/Samsung solution is potentially faster and we believe has great potential to be able to route the call to the proper PSAP (compared with today’s solution of just using cell ID).

Because they also get additional measurements and sensor data, it could work in conjunction with the NEAD to provide dispatchable locations. LaaSer/Samsung also have the ability to look at additional WiFi databases such as enterprise or municipal systems, in addition or crowd-sourced databases of Google’s Android-based ELS.

Q: Are all carrier towers in the country capable of using device-based location at this time?

A: Yes

Q: What is the reliability rate of the WiFi location for MSAG valid address or latitude/longitude?

A: The WiFi location for X/Y is very accurate. As we discussed, there are some anomalies, but if you compare those to the cell ID, they can be identified and eliminated.

Q: Does Google ELS provide elevation? How does it work in a commercial building?

A: Google is working to provide better vertical location. It does today for many devices, but we did not evaluate that feature in our trial.

Q: How do we (a PSAP) become part of testing this technology?

A: Please reach out to West product manager for WDLS, Nora Ligrani, at nligrani@west.com.

NG9-1-1, i3 AND ESInets

Q: Will this technology be part of NG911? Does the FCC have to approve this technology as well?

A: CTIA’s 9-1-1 Location Technologies Test Bed, LLC will benchmark this technology to verify location accuracy and how it is measured in the location estimate. The FCC does not have to approve it.

Q: So with the current limitations in location services, how can we accurately route NG9-1-1 calls?

A: With solutions like LaaSer and, potentially, enhancements by Google and other OEMs, we should be able to get location fast enough to route many 9-1-1 calls using the X/Y initiated by the handset.

Q: If PSAPs or states have an ESInet provider other than West, will this have an adverse impact? Or is it ESInet provider-agnostic?

A: WDLS is primarily dependent on the carrier–it will not matter who provides the ESInet. ESInets and CPE/CADs may or may not implement all of the i3 specification, so functions like location push on updates may vary.

Q: How does this work for a site that is truly i3 enabled?

A: For a truly i3 solution, it will behave the same way. Our goal is to get the accurate location as fast as possible early in the call process.

Other Questions

Q: Have you taken into account the behavioral aspect of “the best single location” being sent to the PSAP? The lesser number of inaccurate locations given to the set of telecommunicators, the less number that are capable to deal with recovery from that inaccuracy. If the location inaccuracy becomes so good, the skills that telecommunicators may have to deal with inaccuracies will atrophy and not get passed along to newer personnel.

A: West believes any location inaccuracy has the potential to delay 9-1-1 response and put lives at risk. Our mission is to work towards delivering a better, faster location to the PSAP.

Q: When do you think ELS will be publicly available through Google’s partners? NENA conference?

A: We recommend contacting Google directly for more information.

Q: Will the ELS location server be compatible with the FCC-mandated dispatchable location technology using the National Emergency Address Database?

A: The NEAD is a database of dispatchable locations associated with Bluetooth low energy (BLE) beacons or WiFi access points. ELS does not currently support the passing of raw WiFi or BLE data to NEAD.

Q: Where online can we register a physical address for a WiFi at government building?

A: That is not available yet, but the NEAD does plan for that.


Thank you, once again, to everyone who participated in the webinar. To view the recording, click here. To learn more about West’s wireless 9-1-1 location solutions, visit us online or contact your account representative.



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