CSRIC working group expects only ‘slightly better’ 911 location accuracy with VoLTE

Existing FCC outdoor location accuracy and testing standards for 911 calls can apply to LTE networks, but only modest improvement in location accuracy is expected with the new architecture, a working group reported to the Communications Security, Reliability and Interoperability Council (CSRIC) on Wednesday.

“It’s not anticipated that modifications to existing outdoor carrier testing methods or procedures would be required due to the introduction of VoLTE [voice over LTE] service,” Brian Fontes, chief executive officer of the National Emergency Number Association (NENA), said during the CSRIC meeting, which was webcast.

“If specific indoor requirements are adopted in the future—and we recognize that the commission has this as an open proceeding—then we anticipate that different testing methodologies would be required, such as testing in representative indoor environments. It’s premature to speculate on the specifics of indoor testing procedures in advance of the FCC’s proceeding on indoor location accuracy, among other things raised in their notice.”

The working group concluded that “VoLTE will have no deleterious impact on the ability of operators to meet the E9-11 location accuracy levels that currently apply to (Commercial Mobile Radio Service),” even with carriers simultaneously running VoLTE and legacy networks during the transition, according to the group’s presentation given Wednesday.

But the group also noted that the FCC should only “expect, over time, location performance with VoLTE to be slightly better or equivalent to 2G and 3G performance,” according to the presentation.

David Simpson, chief of the FCC’s public-safety and homeland-security bureau, said he was puzzled that more location-accuracy improvement was not expected with the implementation of LTE and associated new technologies.

“It does seem to me, though, that the dramatically faster speeds associated with LTE and the additional technical elements to make VoLTE effective help drive a need for much more accurate timing standards in slower-speed networks—certainly, the 2G, 3G—and that, inherently, the more accurate timing standards should very much be translatable into dramatically improved (Observed Time Difference Of Arrival, or OTDOA, accuracy information) than is possible at the lower-speed networks,” Simpson said at Wednesday’s CSRIC meeting.

“So the comment that location accuracy would be potentially slightly better in the VoLTE … I’m not sure I completely understand that. It also strikes me that, if OTDOA is suddenly possibly in broadly scalable way—because the nature in which it’s derived—it kind of makes the indoor/outdoor question moot, or at least less significant,” he said.