Before the
FEDERAL COMMUNICATIONS COMMISSION
Washington, D.C. 20554

In the Matter of
Wireless E911 Location Accuracy
Requirements

PS Docket No. 07-114

REPLY COMMENTS OF T-MOBILE ON PUBLIC NOTICE ON THE ROADMAP FOR
IMPROVING E911 LOCATION ACCURACY

Steve B. Sharkey
Eric Hagerson
T-MOBILE USA, INC.
601 Pennsylvania Ave., NW
Washington, DC 20004
(202) 654-5900

John T. Nakahata
Kristine Laudadio Devine
HARRIS, WILTSHIRE & GRANNIS LLP
1919 M Street, Eighth Floor
Washington, DC 20036
(202) 730-1300
Counsel to T-Mobile USA, Inc.

December 24, 2014

 TABLE OF CONTENTS
I.  INTRODUCTION AND SUMMARY ................................................................................................. 1 
II.  THE ROADMAP’S BENCHMARKS ARE MORE LIKELY TO LEAD TO SUCCESSFUL
IMPROVEMENT OF LOCATION ACCURACY THAN THE COMMISSION’S PROPOSED RULES. ........... 6 
A.  Opponents’ Selective, Piecemeal Criticisms Ignore How the Roadmap Addresses
Issues through a Holistic Framework. ................................................................................ 6 
B.  The Roadmap’s Key Features Create a Path to Success. .................................................... 9 
1.  The Roadmap’s Benchmarks Account for the Time Needed to Evaluate
Technologies in a Real-World Test Bed. ...................................................................... 9 
2.  The Roadmap’s Benchmarks Accommodate the Standardization Process................. 11 
3.  The Roadmap’s Benchmarks Recognize the Ongoing Transition to LTE. ................ 13 
4.  The Roadmap Acknowledges that the Distinction Between Indoor and Outdoor
Calls Disappears when Evaluating Performance with Live Call Data. ...................... 14 
5.  The Roadmap Mandates a 36 Month Evaluation of Dispatchable Location. ............. 14 
III.  THE ROADMAP ESTABLISHES AN EFFECTIVE, AFFORDABLE, AND EXPEDITIOUS PATH TO
DISPATCHABLE LOCATION AS WELL AS IMPROVED WIDE-AREA RADIO-BASED LOCATION. ... 15 
A.  Experience Informs Our Current Understanding of Candidate Location Accuracy
Technologies. .................................................................................................................... 15 
B.  Developments in WiFi and Bluetooth Low Energy Beacons, and Improvements in
cLBS Warranted Reassessment of their Potential for E911. ............................................ 18 
C.  OTDOA Cannot be Equated with, and Is Far Superior to, E-OTD. ................................. 19 
D.  WiFi and Bluetooth Beacons Cannot be Judged by Analogy to RF Fingerprinting. ........ 19 
IV. CONCLUSION............................................................................................................................ 21 

 I.

INTRODUCTION AND SUMMARY
T-Mobile USA, Inc. (“T-Mobile”),1 the Uncarrier that has revolutionized the wireless

industry by offering consumer friendly products and services as well as building the nation’s
fastest Long Term Evolution (“LTE”) network, is committed to ensuring that its customers can
be located whenever they place an emergency call 911. As part of that commitment, T-Mobile is
proud to be a signatory, along with the Association of Public Safety Communications Officials
International (“APCO”), the National Emergency Number Association (“NENA”) and other
national wireless carriers, to the Roadmap for Improving E911 Location Accuracy
(“Roadmap”).2 The Roadmap represents the best path forward for real improvement in location
accuracy, taking advantage of the built-in location features of the LTE standard, and leveraging
the continued deployment and improvement of Bluetooth location beacons and commercial WiFi
access points and market-driven improvements in commercial Location-Based Services
(“cLBS”) for the benefit of wireless 911 callers. The Roadmap directs the focus of all
stakeholders to the gold standard for wireless E911—a dispatchable, validated civic location,
with floor or suite information where necessary, that will not be subject to reverse geolocation
errors in Public Safety Answering Point (“PSAP”) maps and that does not require developing
and implementing new, three dimensional mapping technology for every PSAP.
Furthermore, the Roadmap does not rely solely on a dispatchable location approach: it
establishes aggressive but feasible benchmarks for assessing and improving wide-area radiobased location technologies, and, for the first time, establishes enforceable metrics based on live

1

T-Mobile USA, Inc. is a wholly-owned subsidiary of T-Mobile US, Inc., a publicly-traded
company.

2

Letter from Scott Bergman, Counsel, CTIA—The Wireless Association, to Marlene Dortch,
Secretary, Federal Communications Commission, PS Docket No. 07-114 (filed Nov. 18,
2014) (“Roadmap”).

 911 call yields that use high accuracy location technologies. It also provides a means to separate
the exaggerated claims of location technology vendors from verifiable performance so that
consumers, first responders, and carriers can assess whether a location technology can actually
deliver what its proprietors claim. It does all of these things within a transparent, technologyneutral, forward-looking framework. The result maximizes the chances of real, near-term, and
long-term improvement for consumers and the first responders trying to reach them.
In contrast, and despite the claims of some commenters, the rules initially proposed in the
Third Further Notice of Proposed Rulemaking (“FNPRM”)3 will provide only an illusory benefit
because the proposed benchmarks and timeframes are infeasible. Given the need to conduct
standards development, to design and test hardware, and to deploy both new network equipment
and, for many technologies, handsets, it is clear that, in fact, no carrier would be able to meet
those benchmarks, even if the technology could live up to the claims of vendors. No one has
placed into the record a project plan that uses wide-area radio location technologies alone or in
combination with A-GNSS, to achieve 50 meter accuracy for 67% of all indoor 911 calls within
two years, 50 meter accuracy for 80% of all indoor 911 calls within five years, and 3 meter
vertical accuracy for 67% of all indoor 911 calls within three years, and 80% within five years.
The call to adopt those requirements and associated timelines is, in the end, based on nothing
more than wishful thinking.
The Roadmap begins by evaluating candidate technologies to determine what, in fact, is
possible and in what timeframe.4 The Roadmap incorporates time for necessary standards

3

Wireless E911 Location Accuracy Requirements, Third Further Notice of Proposed
Rulemaking, FCC 14-13, 29 FCC Rcd. 2374 (“FNPRM”).

4

Roadmap at 1.
2

 development5—which cannot simply be wished away. And the Roadmap recognizes the
impending deployment and use of new technologies that carriers are already putting into place,
like Observed Time Difference of Arrival (“OTDOA”) and Assisted-Global Navigation Satellite
Systems (“A-GNSS”), both of which will significantly improve the existing performance of both
indoor and outdoor location estimation.6 Other location technology vendors have asked the
Commission to discount, if not ignore entirely, these new technologies.7 But it would be wholly
arbitrary and capricious to ignore the fact that carriers are already implementing technologies
that will work as well or better than the technology solutions offered by other, disappointed
vendors. Finally, and perhaps most critically, the Roadmap sets into motion the necessary steps
to implement and deploy a true dispatchable location solution8—something not one of the
Roadmap’s critics has attempted to do and for which none of them has a proposed alternative.
But the Roadmap also requires a hard-nosed review of the progress being made on a dispatchable
location solution, with backstop requirements for heightened accuracy location determinations
and alternative means of estimating vertical location.
T-Mobile recognizes that dispatchable location will likely never be available for every
wireless 911 caller, in many cases because the caller is located outdoors in places such as parks,
trails, or highways. Wide-area radio and satellite based technologies will continue to be needed,
both outdoors and indoors. Use of additional GNSS constellations and OTDOA will not only
improve outdoor location, but provide a backstop for those indoor locations not covered by the

5

Roadmap §§ 2(d), 5.

6

Roadmap § 3.

7

See, e.g., Comments of TruePosition, Inc. at 3-5 (“TruePosition Comments”); Comments of
Polaris Wireless at 4 (“Polaris Comments”). Unless otherwise noted, all comments cited
were filed on December 15, 2014, in PS Docket No. 07-114.

8

Roadmap § 2.
3

 dispatchable location system. The Roadmap does not foreclose the possibility that alternative
technologies could result in further substantial improvements for what should be a diminishing
number of locations that would lack a heightened accuracy location estimate. But those
additional technologies must be market tested, with verifiable and demonstrable benefits. The
Commission has already seen Uplink-Time Difference of Arrival (“U-TDOA”) fail to meet its
promised performance claims in the early days of Phase II.9 Very little has changed to make that
solution any better today than 11 years ago. NextNav, for all its claims, will never be
ubiquitously deployed,10 which raises the question—how is a proprietary overlay terrestrial
beacon system that will only be deployed in major metropolitan areas, and that does not work if
not locally deployed to a high beacon density, superior to a WiFi or Bluetooth-based
dispatchable location solution that is already being ubiquitously and naturally deployed in
virtually every building where it will be needed for emergency services across the country? Or,
how would a NextNav system be superior to the OTDOA technology that is already being
deployed in production handsets and across entire wireless networks—using the base stations
themselves as terrestrial beacons—where if a 911 call can be made, it most likely can be located
using OTDOA regardless of whether the caller is in a major metropolitan area or elsewhere?
In his recent blog post, Adm. Simpson recognized that, in many respects, the “indoor
location gap” is not about technology but about implementation.11 The new technologies already
being implemented, including OTDOA, A-GNSS and cLBS, in addition to dispatchable address,
9

Comments of T-Mobile USA, Inc., at 13-14.

10

See Letter from Bruce A. Olcott, Counsel, Progeny LMS, LLC, to Marlene H. Dortch,
Secretary, FCC, WT Docket No. 11-49, Attachment at 13 (filed Mar. 21, 2013)
(“NextNav/Progeny Presentation”).

11

Adm. David Simpson, Chief, Public Safety & Homeland Security Bureau, FCC, Closing the
911 Location Accuracy Gap, OFFICIAL FCC BLOG (Dec. 17, 2014) (“Adm. Simpson Blog
Post”); see also NextNav/Progeny Presentation 13.
4

 will substantially close that “indoor location gap.” But as Adm. Simpson also recognized,
implementation must be done “effectively, affordably, [and] expeditiously.”12 Indeed, rules
themselves must be implementable, i.e., they must be technically and economically feasible, in
order to avoid being arbitrary and capricious.13 Effective, affordable, and expeditious
implementation, though, can only be achieved where technology has been proven to be viable
and is offered competitively in a non-sole-sourced manner; because switching barriers are high,
sole-sourced technology predictably will stagnate over time.
In deciding what is reasonable to expect from currently planned technologies and
solutions, and what, if anything, could be gained from additional location technology
alternatives, rational decision making requires facts first, and then conclusions. The Roadmap
does just that, by establishing a test bed open to all candidate solutions, for apples-to-apples
comparisons, including evaluation of vertical location methods. Roadmap opponents would
reach judgment first, and only later examine the facts.
The Roadmap sets forth a timeline that addresses the development and deployment of a
dispatchable location solution using market-tested technologies like WiFi and Bluetooth.14 It
also lays out the necessary steps needed to evaluate wide-area radio-based technologies and
closes the capability gap by ensuring that carriers, vendors, and public safety will not spin their
wheels, wasting time and money, trying to implement technologies that may—and in some cases,
certainly will—never achieve any improvement in location accuracy.15 Moreover, by building in
time to evaluate—and allow for standardization of—candidate technologies, the Roadmap

12

Adm. Simpson Blog Post.

13

Nuvio Corp. v. FCC, 473 F.3d 302, 303 (D.C. Cir. 2006).

14

Roadmap § 2.

15

See Roadmap §§ 1, 3.
5

 accommodates the myriad concerns that accompany such technology deployments, including
critical security and privacy issues.16
II.

THE ROADMAP’S BENCHMARKS ARE MORE LIKELY TO LEAD TO SUCCESSFUL
IMPROVEMENT OF LOCATION ACCURACY THAN THE COMMISSION’S PROPOSED RULES.
A.

Opponents’ Selective, Piecemeal Criticisms Ignore How the Roadmap
Addresses Issues through a Holistic Framework.

The Roadmap establishes a path forward for closing the “indoor location accuracy gap”
by establishing aggressive but feasible benchmarks for wireless E911 location improvement.
Rather than addressing the framework as a comprehensive solution, however, critics of the
Roadmap instead pick and choose selected proposals and analyze them out of context. For
instance, several commenters allege that the Roadmap absolves carriers of any accountability.17
Others claim that the Roadmap contains no real performance metrics, or that the Roadmap uses
outdoor location measurements to mask indoor location errors.18 Still others argue that the
Roadmap is unenforceable.19 None of this is true, and all of these claims are built on
misrepresentations and distortions.
These complaints, of course, are disproven in the Roadmap itself. First, and as noted by
AT&T, the Roadmap commits carriers to support a test bed for evaluation of candidate
technologies, to collect and provide live wireless E911 call data, including, for the first time
16

Roadmap § 2(e).

17

See, e.g., Comments of NextNav, LLC at 23-25 (“NextNav Comments”); Polaris Comments
at 3; TruePosition Comments at 3, 17; Comments of BRETSA at 5-9 (“BRETSA
Comments”); Comments of the Hawaii Enhanced 911 Board at 1 (“Hawaii Comments”);
Comments of AARP at 1 (“AARP Comments”).

18

See, e.g., NextNav Comments at 27-33; Comments of The National Association of EMS
Physicians, et al., at 2; BRETSA Comments at 8; TruePosition Comments at 18; Comments
of Telecommunications for the Deaf and Hard of Hearing at 3.

19

See, e.g., BRETSA Comments at 5-9; TruePosition Comments at 20; NextNav Comments at
4-5; Comments of the Congressional Fire Services and International Association of Fire
Fighters at 1 (“IAFF Comments”).
6

 position source yields, and—most importantly—to meet specific location performance metrics
with respect to the percentage of calls with a blended composite accuracy of 50 meters.20 This
“three-legged stool…facilitate[s] monitoring performance and compliance”21 to ensure
accountability. The test bed will allow carriers and public safety to assess the relative
performance of each location technology in both outdoor and indoor environments, and then to
monitor the frequency of each location method utilized for live 911 calls. This provides
unparalleled visibility into location performance, including the ability to monitor performance
trends over time.
Second, the Roadmap is framed as “trust but verify.” It lays out specific steps that
carriers commit to take, and processes to evaluate progress in carrying out those steps. These
evaluations will be used by carriers to demonstrate progress toward a workable dispatchable
location solution or to pursue other solutions, whether alone or in combination with dispatchable
location. And all signatories have agreed that key provisions in the Roadmap—including
timeframes for handset development and deployment, network design and development,
introduction of new devices, and performance metrics—should be codified, to ensure
compliance.22
Still other commenters create the record that they want the Commission to see—such as
the survey results submitted by FindMe911, in which that organization collected responses to
questions that all but guaranteed a pre-determined conclusion.23 It is telling, despite

20

Comments of AT&T Services, Inc. at 3 (“AT&T Comments”).

21

Id. at 3.

22

Roadmap § 7; see also AT&T Comments at 11.

23

For instance, FindMe911 asked those taking the survey the following questions, presenting
options that pre-determine responses as well as inaccurately represent the content of the
Roadmap:
7

 FindMe911’s claims that public safety is nearly monolithic in its opposition to the Roadmap,24
that numerous public safety organizations have come out in support of the Roadmap,
acknowledging not only that the Roadmap provides a path to true dispatchable location but also
that the timeframes and benchmarks set forth in the Roadmap are more realistic—and therefore
more likely to be successful—than those proposed by the Commission.25

x

Whether takers supported a plan that “Sets specific location requirements for indoor
wireless 9-1-1 calls (FCC plan)” or a plan that “Does not require specific locations for
indoor wireless 9-1-1 calls (Phone company plan)”

x

Whether takers supported a plan that “Sets vertical accuracy requirements to help find
callers in tall buildings (FCC plan)” or a plan that “Does not set any vertical accuracy
requirements (Phone company plan)”

x

Whether takers supported a plan that “Covers all existing and future cell phones in use
(FCC plan)” or a plan that “Only covers future cell phones with a special chipset installed
(Phone company plan)”

Comments of FindMe911 at 8-10 (“FindMe911 Comments”).
24

FindMe911 Comments at 2.

25

See, e.g., Comments of the Texas 9-1-1 Entities; Letter from Allen Turner, Communications
Coordinator, County of Orleans, New York, Office of the Sheriff, to Marlene H. Dortch,
Secretary, FCC, PS Docket No. 07-114 (Dec. 8, 2014); Letter from Steuben County Fire
Service, to Marlene H. Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 1, 2014); Letter
from Jeffrey Schemmer, Indiana NENA President, to Marlene H. Dortch, Secretary, FCC, PS
Docket No. 07-114 (Dec. 8, 2014); Craig Sheets, Virginia NENA President, to Marlene H.
Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 6, 2014); Letter from John Merklinger,
President, New York State 911 Coordinators Association, to Marlene H. Dortch, Secretary,
FCC, PS Docket No. 07-114 (Dec. 8, 2014); Letter from Dee Ann Summersett, Michigan
NENA President, to Marlene H. Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 5,
2014); Letter from David Hopkins, New York NENA President, to Marlene H. Dortch,
Secretary, FCC, PS Docket No. 07-114 (Dec. 1, 2014); Letter from Luiz Casanova, Assistant
Chief of Police, New Haven Police Department, to Marlene H. Dortch, Secretary, FCC, PS
Docket No. 07-114 (Dec. 17, 2014); Letter from Santina Rogers, Alabama NENA, to
Marlene H. Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 8, 2014); Letter from John
Merklinger, Director, City of Rochester, New York, Emergency Communications
Department, to Marlene H. Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 8, 2014);
Letter from Michael Allen, Oswego County, New York, E-9-1-1 Emergency
Communications Department, to Marlene H. Dortch, Secretary, FCC, PS Docket No. 07-114
(Dec. 8, 2014); Letter from Paul Hartnett, Director, Madison County New York, Emergency
Communications, to Marlene H. Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 9,
2014); Letter from Randall Lewis, Tennessee NENA Chapter President, to Marlene H.
8

 B.

The Roadmap’s Key Features Create a Path to Success.

The Roadmap establishes parallel paths to success for dispatchable location and widearea radio location based-solutions by (1) starting with evaluation of technologies; (2) building
the standards-setting process into the timeline; (3) acknowledging the transition to LTE in
benchmarks; (4) recognizing that a blended standard is necessary where live call data is used for
performance evaluation; and (5) having a 36 month evaluation to determine whether dispatchable
location is on track or whether alternative location technologies need to be employed. Viewed as
a comprehensive proposal, it is clear that the Roadmap creates an ecosystem under which real
and significant improvement to location accuracy will be realized in a much shorter overall
timeframe than under the Commission’s proposal.

1.

The Roadmap’s Benchmarks Account for the Time Needed to
Evaluate Technologies in a Real-World Test Bed.

The test bed proposed in the Roadmap will, as noted by APCO, “be very useful for public
safety. Unlike previous location accuracy test beds, we will have the opportunity to assess the
performance of any technology, as well as the usefulness of the technology in PSAPs and in a
realistic call and response environment.”26 By starting with the evaluation of technologies, the
Roadmap allows carriers and public safety, in partnership, to see what works and what doesn’t—
including evaluation under conditions specifically designed to stress vertical location methods—
across geographic morphologies in a technology-neutral and non-discriminatory manner. In

Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 9, 2014); see also e.g., Letter from
Philip Byers, Former Sheriff, Rutherford County, North Carolina, to Marlene H. Dortch,
Secretary, FCC, PS Docket No. 07-114 (Dec. 17, 2014); Letter from Thom Gooslby, North
Carolina Governor’s Crime Commission, to Marlene H. Dortch, Secretary, FCC, PS Docket
No. 07-114 (Dec. 17, 2014); Letter from Rep. Anthony D’Amelio, State Representative, 71st
Dist., Connecticut, to Marlene H. Dortch, Secretary, FCC, PS Docket No. 07-114 (Dec. 17,
2014).
26

Comments of APCO at 5 (“APCO Comments”).
9

 addition, the Roadmap also requires a pre-standards demonstration of a dispatchable location
solution within nine months.
Far from serving as a delay tactic, as some have characterized it,27 the test bed ensures
that stakeholders do not waste time attempting to deploy technologies that cannot match their
proprietors’ optimistic claims. It is perhaps unsurprising, then, that the most vocal critics of the
test bed happen to be technology vendors whose proposed solutions were either pulled from the
Commission’s Communications, Security, Reliability and Interoperability Council (“CSRIC”) III
indoor test bed (TruePosition) or whose solutions were shown in the CSRIC III test bed to
perform poorly and proven unable to provide any real improvement on technologies already in
use (Polaris).28
The record shows, in fact, that many public safety entities support a framework in which
candidate technologies are thoroughly evaluated before implementation. For instance, the
Hawaii Enhanced 911 Board, despite opposing many elements of the Roadmap, also
acknowledges that the test bed proposal is a positive development.29 The National Association
of State 911 Administrators (“NASNA”) asks the Commission to codify the test bed proposals
and notes that it supports the “real-world conditions” of the proposed test bed, as well as the
validation of data using live 911 calls.30 And the International Association of Chiefs of Police
(and affiliated organizations) (“IACP”) agree that any technology to be adopted for location

27

See, e.g., BRETSA Comments at i; TruePosition Comments at Exhibit 1; Comments of the
International Municipal Signal Association at 6-7 (“IMSA Comments”); IAFF Comments at
2; NextNav at 4-5.

28

See generally TruePosition Comments; Polaris Comments.

29

Hawaii Comments at 3.

30

Comments of NASNA at 2.
10

 accuracy must be tested31 and that a technology-neutral approach is critical.32 These tenets are
central to the Roadmap. Such a facts-first framework is eminently logical and will ultimately
shorten the timeframe to realize actual improvements for first responders; given the fact that new
location technologies require years to deploy and permeate into the hands of consumers, getting
the underlying location technology wrong is a costly and time consuming detour for all
stakeholders. As one of the carriers that initially sought to deploy Enhanced-Observed Time
Difference (“E-OTD”) for Phase II locations, T-Mobile has first-hand experience with the
problems and disappointment caused when a technology vendor cannot match its performance
claims.

2.

The Roadmap’s Benchmarks Accommodate the Standardization
Process.

The standardization process must precede any deployment or implementation.33 Under
the Commission’s proposed rules, carriers would be required to meet onerous, infeasible
benchmarks within two years.34 But, with the exception of A-GNSS and OTDOA, the candidate
solutions require standards-setting to enable implementation, and such processes will consume a
significant portion of that two-year window,35 leaving insufficient time for network deployment,
handset development, and change-out.36 The fact is that handsets incorporating those new

31

Comments of the International Association of Chiefs of Police, et al. at 2-3 (“IACP
Comments”).

32

Id. at 2.

33

See Roadmap § 2(d).

34

FNPRM ¶ 3.

35

The Alliance for Telecommunications Industry Solutions (“ATIS”) has already established a
special, cross-functional Emergency Location Task Force (ELOC TF) to begin developing
the standards needed to support the commitments defined in the Roadmap.

36

As discussed in Part II.B.3, infra, handset turnover would be required for all candidate
vertical location solutions in order to attempt to meet the Commission’s proposed rules.
11

 standards will not be widely deployed within those two years and, realistically, probably will not
ever be available. In other words, the two-year, 50 meter indoor benchmark is not a realistic
option (i.e., is infeasible) and sets carriers up to fail. It thus would be arbitrary and capricious
and a disservice to all stakeholders.
When the Commission established similar benchmarks in the early days of Phase II, the
result was substantial delay, due to waivers, lawsuits, consent decrees, and ultimately revised
deadlines, which delayed implementation of actual location improvements to the detriment of all
involved, including consumers and public safety.37 Despite the lessons of history, some
commenters today continue to call for adoption of benchmarks on a short, infeasible timeframe,
ignoring the technical realities involved.38
The Roadmap, in contrast, gives carriers, manufacturers, and technology vendors time
(albeit an aggressive schedule) to allow the appropriate standards bodies to do their work. This
ensures that any technologies adopted for location technology are properly integrated into

37

See, e.g., Revision of the Commission’s Rules to Ensure Compatibility with Enhanced 911
Emergency Calling Systems, Fourth Memorandum Opinion and Order, FCC 00-326, CC
Docket No. 94-102 (rel. Aug. 24, 2000) (extending phase-in deadlines); Revision of the
Commission’s Rules to Ensure Compatibility with Enhanced 911 Emergency Calling
Systems, Order, FCC 01-294 & 01-296, CC Docket No. 94-102 (rel. Oct. 2, 2001) (granting
waivers to AT&T and Cingular of handset requirements); AT&T Consent Decree, FCC 02174, PS Docket No. 94-102 (June 12, 2002); Cingular Consent Decree, FCC 03-129, PS
Docket No. 94-102 (June 6, 2003); T-Mobile Consent Decree, FCC 03-172, PS Docket No.
94-102 (July 14, 2003); Wireless E911 Location Accuracy Requirements et al., Report and
Order, FCC 07-166, PS Docket No. 07-114 (rel. Sept. 11, 2007) (adopting new benchmarks
for handset- and network-based accuracy); Rural Cellular Ass’n v. FCC, Nos. 08-1069, 081070, 08-1075, 08-1076, 2008 WL 9391132 (D.C. Cir. Mar. 25, 2008) (per curiam); Wireless
E911 Location Accuracy Requirements, Second Report and Order, FCC 10-176, PS Docket
No. 07-114 (rel. Sept. 23, 2010).

38

See, e.g., FindMe911 Comments at 1; Hawaii Comments at 2; Comments of NARUC at 5
(“NARUC Comments”); Comments of the Nebraska Public Service Commission at 2
(Nebraska PSC Comments”).
12

 networks and handsets and are part of a viable technology ecosystem. This is a critical step that
is simply unaccounted for under the two- and three-year timeframes proposed in the FNPRM.

3.

The Roadmap’s Benchmarks Recognize the Ongoing Transition to
LTE.

The Roadmap recognizes that to achieve high levels of accuracy across the subscriber
base nationwide, any benchmarks must look to new wireless network technologies—i.e., Voice
over LTE (“VoLTE”), which will, for the first time, allow multiple location queries to be
launched simultaneously, rather than serially.39 This means that a carrier can simultaneously
seek an A-GNSS location estimate and other location estimates such as OTDOA or cLBS, and
then make the best location estimate available to the PSAP. LTE networks are already here: TMobile’s LTE network covers 260 million Americans and will reach 300 million by the end of
2015—approximately 94% of the total U.S. population.
Critics who claim that people using Second Generation (“2G”) and Third Generation
(“3G”) phones will be abandoned overlook the fact that 2G and 3G networks would require
location estimates to be sequenced, which could result in fewer high accuracy location estimates
within an acceptable time parameter. Furthermore, during the multiyear period it would to take
to deploy alternative location technologies (at least five years) many 2G networks are likely to be
sunset. Additionally, the majority of wireless subscribers will have migrated to VoLTE within
five years—essentially the same timeframe that any realistic location performance
improvements, regardless of specific methods, could be introduced and realized.40 Such claims
also ignore the plain fact that, to meet the Commission’s proposed benchmarks—particularly the
39

See Roadmap § 2(f).

40

Moreover, as T-Mobile has pointed out, there is virtually no chance that modifications to the
2G and 3G standards to accommodate new location technologies will ever take place. See
Reply Comments of T-Mobile USA, Inc., PS Docket No. 07-114, at 26-27 (July 14, 2014)
(“T-Mobile Location Accuracy FNPRM Reply Comments”).
13

 vertical benchmarks—handsets will have to be changed out. In other words, under either
proposal, handset change out must occur. But the change out to VoLTE handsets is already
underway as carriers migrate to 4G networks; that is not the case for as-yet-unstandardized and
unspecified location technologies.

4.

The Roadmap Acknowledges that the Distinction Between Indoor and
Outdoor Calls Disappears when Evaluating Performance with Live
Call Data.

The Roadmap recognizes that there is no way to automatically distinguish, in a live call
environment, between an indoor and an outdoor 911 call. A blended indoor/outdoor metric
based for the first time on live, production 911 calls, allows carriers to focus on improvement
overall rather than on trying to figure out which calls are subject to which requirement—
avoiding any further bifurcation of rules. Though critics attempt to paint this proposal as a
watering down of the Commission’s indoor proposal,41 it is no such thing. The blended
indoor/outdoor benchmarks represent substantial improvement over the current outdoor
benchmarks42—while also incorporating real and testable metrics for indoor calls.

5.

The Roadmap Mandates a 36 Month Evaluation of Dispatchable
Location.

Finally, the Roadmap requires evaluation of the proposed dispatchable location solution
at the 36-month mark, to review the progress of its implementation. If the dispatchable location
solution is not on track, the Roadmap requires stakeholders to move to alternative location

41

See, e.g., FindMe911 Comments at 3; TruePosition Comments at Exhibit 1.

42

Depending upon which “compliance path” a carrier is operating under, current outdoor rules
require either 100 meters for 67 percent of calls and 300 meters for 90 percent of calls, or 50
meters for 67 percent of calls and 150 meters for 90 percent of calls. The Roadmap requires
either a dispatchable location or 50 meter accuracy at increasing yield levels—beginning at
40 percent of calls and ending up at 80 percent of calls, see Roadmap at § 4(c)—resulting in
a substantial tightening of the accuracy required for outdoor 911 calls—another goal of the
Commission.
14

 solutions—solutions which, because of the parallel processes of dispatchable location
implementation and test bed evaluation of alternative solutions, will be much closer to
implementation than they otherwise might be. By setting forth this parallel process, the
Roadmap facilitates improvement in indoor location accuracy that cannot be realized where
stakeholders must invest their efforts in a single track.
III.

THE ROADMAP ESTABLISHES AN EFFECTIVE, AFFORDABLE, AND EXPEDITIOUS PATH
TO DISPATCHABLE LOCATION AS WELL AS IMPROVED WIDE-AREA RADIO-BASED
LOCATION.
Effective, affordable, and expeditious improvement in location accuracy can only come

where benchmarks follow technological evaluation. History has proven that “if you mandate it,
they will build it” rules do not work. Without rigorous evaluation of candidate technologies in a
common, real-world environment administered transparently by a neutral third party, we cannot
know anything about what is, in fact, feasible. Yet some critics of the Roadmap call for just
that—adoption of specific benchmarks divorced from any grounding in actual test results.43
A.

Experience Informs Our Current Understanding of Candidate Location
Accuracy Technologies.

Stakeholders today already have a good idea about the capabilities of some candidate
technologies, from prior deployments in the emergency services context, to deployments in the
commercial context, to prior testing, either in a test bed or laboratory setting. Thus we know the
following about Radio Frequency (“RF”) Fingerprinting, NextNav’s terrestrial beacon system,
U-TDOA, OTDOA, A-GNSS, and WiFi and Bluetooth beacons:
x

From the CSRIC III test bed, we know that Polaris’s RF Fingerprinting solution will
not provide results that meet either the FCC’s or the Roadmap’s benchmarks.44

43

See, e.g., FindMe911 Comments at 2; Hawaii Comments at 2; NARUC Comments at 5;
Nebraska PSC Comments at 2.

44

CSRIC III, Working Group 3, E9-1-1 Location Accuracy, Indoor Location Test Bed Report,
27 (Mar. 14, 2013), available at http://transition.fcc.gov/bureaus/pshs/advisory/
15

 x

We know that, in the CSRIC III test bed, NextNav’s solution failed to place the caller
in the correct building for two-thirds of calls.45 Furthermore, it is not standardized
and has not been integrated into production handsets (which is a 3-4 year process—
not counting the time required to get these handsets into the hands of consumers).46
We also know that NextNav requires a high density overlay deployment of terrestrial
beacons, which will only be possible in certain top metropolitan areas where they
hold licensed spectrum. We also know that NextNav does not intend to deploy on a
nationwide basis in all markets,47 leaving many 911 callers without access to their
proposed solution, particularly in smaller cities. Thus even where a NextNav
deployment would be available, it would not meet the 50 meter horizontal accuracy
benchmark proposed by the Commission in urban or dense urban indoor
environments.

x

We do not know how U-TDOA will perform in an apples-to-apples indoor test
because TruePosition pulled it from the CSRIC III test bed, preferring “go it alone”
testing that it could control.48 Nonetheless, we have a good understanding about its
significant shortcomings—both in terms of achievable performance and
deployment/operational limitations—given the prior real-world deployments for 2G
networks and its current unavailability for 3G and 4G networks.49 We also know that
U-TDOA has no vertical component.

x

While we are confident in the improvements that OTDOA and A-GNSS—which are
already being deployed—will provide because we have some idea of the
improvement we can expect based on initial internal testing, the test bed will provide

csric3/CSRIC_III_WG3_Report_March_%202013_ILTestBedReport (“CSRIC III WG3
Indoor Test Bed Report”).
45

CSRIC III WG3 Indoor Test Bed Report at 27.

46

See T-Mobile Location Accuracy FNPRM Reply Comments at 18-19 & Appendix ¶ 15; see
also Comments of NextNav, PS Docket No. 07-114, at 13 (May 12, 2014) (acknowledging
that NextNav has just begun discussing the necessary standards work to integrate its
technology into handsets).

47

See NextNav/Progeny Presentation at 13.

48

See T-Mobile Location Accuracy FNPRM Reply Comments at Appendix ¶ 18.

49

U-TDOA has not been deployed by a U.S. wireless operator on any network other than 2G
GSM. TruePosition’s recommended implementation of U-TDOA for 3G and 4G networks
would require substantial modifications to these networks, including functionality that is not
standardized and has not been tested, specifically, to require the handset to transmit at full
power during a 911 call. In addition, the use of U-TDOA for 3G and 4G networks would
require the deployment of Location Measurement Units (LMUs) at each base station, even
though modern base station architecture does not accommodate the insertion of these LMUs
between the transceiver and the uplink antennas—making U-TDOA virtually incompatible
with modern radio access networks.
16

 empirical evidence to demonstrate their heightened accuracy and yield.50
Furthermore, the necessary standards work has already been completed and
functionality has been integrated into production handsets.
x

Finally, we will be able to empirically demonstrate the benefits of leveraging WiFi
and Bluetooth beacons, both via dispatchable address and crowdsourcing. We are
confident they will perform well because of the many successful demonstrations of
this technology over the last several months—including in multi-story buildings, and
we know that this technology has been successfully deployed in enterprise contexts
for many years.

The test bed proposed in the Roadmap will allow, for the first time, an apples-to-apples
comprehensive evaluation of these technologies across key morphologies. By starting with
evaluation of candidate technologies, the Roadmap improves the efficacy of any solutions that
are later implemented.
In addition, the Roadmap proposals also allow privacy and security concerns to be
addressed from the outset. It is not a flaw of the Roadmap that those protections are not
specified now. As the Roadmap recognizes, these protections are important, and need to be
developed as part of the specifications for the National Emergency Address Database (“NEAD”).
Furthermore, and with respect to privacy and security issues, T-Mobile agrees with Public
Knowledge that the information contained in the database needs to be secure and protected from
abuse and misuse.51 Location information must be protected against unauthorized access and

50

T-Mobile will also deploy additional A-GNSS functionality on its 3G UMTS network,
specifically by adding GLONASS functionality, to improve location performance beyond
that obtainable by A-GPS alone. Note that TruePosition also relied on GLONASS satellites
in conducting its testing in Wilmington. See Joe Marx, Red Herrings and Bogeymen: Setting
the Record Straight on TruePosition’s Misinformation Campaign, AT&T PUBLIC POLICY
BLOG (Dec. 12, 2014), http://www.attpublicpolicy.com/public-safety/red-herrings-andbogeymen-setting-the-record-straight-on-truepositions-misinformation-campaign/; see also
TruePosition Indoor Test Report, Wilmington, DE, at 1 (June 18, 2014), available at
http://www.trueposition.com/assets/Uploads/TP-TestResults-2014.pdf.

51

See generally Comments of Public Knowledge, et al.
17

 only necessary information should be included in the NEAD. We look forward to working with
interested stakeholders to develop the standards and procedures to ensure that is the case.
B.

Developments in WiFi and Bluetooth Low Energy Beacons, and
Improvements in cLBS Warranted Reassessment of their Potential for E911.

Some critics of the Roadmap refuse to accept technological advancements that now make
dispatchable location based on local-area radio beacons feasible for emergency services. For
example, TruePosition claims that carriers are “changing their minds” regarding the feasibility of
using WiFi for wireless E911.52 NextNav makes similar claims.53 Though both technology
vendors correctly note that carriers and CSRIC II identified shortcomings with the use of WiFi in
the emergency communications context in the past,54 they ignore the recent developments—
including the widespread use of WiFi positioning technologies in the commercial sector—that
led carriers and others to reconsider this technology. The introduction of Bluetooth low energy
technologies has had a similar effect, along with other technological advancements, including
improvements in WiFi performance and handset power management, greatly expanded
penetration of WiFi and Bluetooth functionality in common production handsets, ubiquitous
deployment of WiFi access points both commercially and residentially, rapidly expanding use of
small cells in various indoor environments, the emergence of vendors in this technology space
for E911 (including enterprise vendors that have successfully demonstrated the use of this
technology for emergency services), and finally, the development of highly comprehensive and
accurate databases via crowdsourcing, including self-healing and automated consistency checks.

52

TruePosition Comments at 6-7.

53

NextNav Comments at 37-42.

54

TruePosition Comments at 5-9; NextNav Comments at 38.
18

 None of these advancements were available when WiFi and other “beacon based” technologies
were evaluated by CSRIC II.
C.

OTDOA Cannot be Equated with, and Is Far Superior to, E-OTD.

TruePosition also attempts to disparage the promising new OTDOA location method by
asking the Commission to equate OTDOA with the failed E-OTD, developed for GSM networks
in the late 1990s, even though E-OTD was a very different technology than OTDOA.55 For
instance, OTDOA has been integrated into the LTE physical layer using wider bandwidth and
time-coordinated Positioning Reference Signals on the downlink for high accuracy time-ofarrival measurements—improving the “hearability” of surrounding base stations and virtually
eliminating the classic “near-far problem” which significantly degrades both E-OTD and UTDOA. OTDOA also benefits from multi-band (inter-frequency) functionality—allowing many
more surrounding base stations to be measured for a given 911 call, further improving accuracy.
OTDOA over LTE is synchronous, while GSM networks did not have synchronous downlinks
when E-OTD was tested, which introduced additional error sources. And OTDOA enjoys broad
industry support across multiple wireless carriers and vendors allowing a healthy ecosystem and
continual technological evolution.
D.

WiFi and Bluetooth Beacons Cannot Be Judged by Analogy to RF
Fingerprinting.

Finally, in a further attempt to spread confusion, TruePosition also asks the Commission
to equate the relatively straight-forward use of WiFi and Bluetooth beacons and the NEAD to
develop dispatchable locations, with the very complicated and problem-prone method of RF
Fingerprinting. The two location methods could not be more different. The dispatchable
location solution relies on provisioned addresses of specified access points and beacons that are
55

TruePosition Comments at 3.
19

 correlated in the NEAD. In contrast, the necessary RF Fingerprinting database attempts to
maintain an accurate mapping of signal strengths (radio frequency signatures) for surrounding
cell sites in any given location—with all of the challenges that entails—including the fact that
radio frequency signatures are subject to a variety of changes such as changes to cell sites
(location, power level, transmission frequency, antenna downtilt/azimuth/beamwidth),
surrounding buildings, seasons, height above ground, and other common parameters.
*

*

*

The Roadmap proposals should be adopted in lieu of the Commission’s proposed indoor
accuracy benchmarks and timeframes, as the Roadmap captures many of the issues the
Commission hoped to address with its proposals. Specifically, the Roadmap addresses various
Commission proposals as follows:

56

x

The 50 meter horizontal accuracy benchmark is addressed through the dispatchable
location solution and other proven heightened accuracy location methods.

x

Provision of actionable vertical information is addressed within the dispatchable
location solution and the commitment to standardize the delivery of uncompensated
barometric pressure data to PSAPs with 911 calls and to participate in the evaluation
process for both uncompensated and compensated barometric pressure based location
solutions.

x

Demonstration of compliance nationally is addressed by testing in representative
indoor environments in the test bed process patterned after the CSRIC III indoor test
bed.

x

Improved visibility for public safety is addressed by carriers’ agreement to provide to
public safety reports on a quarterly basis detailing the frequency of specific
technologies used to generate location estimates for 911 calls, which allows public
safety to monitor improvements of heightened accuracy methods over time.

x

Inclusion of Phase II (heightened accuracy) yield requirements are met by carriers’
agreement to meet specific 50 meter benchmarks over a time period that aligns
closely with the Commission’s original proposals.56

As envisioned by the Commission in the FNRPM, the Roadmap approach includes all
location results (including Phase I results) in determining yields. Furthermore, as the
20

 Other proposals from the FNRPM that will improve indoor location should be codifed
without modification:

IV.

x

The Commission should standardize uncertainty estimates for non-dispatchable
location results across all carriers and location methods at a 90% confidence level.57
Carriers have long agreed with public safety that standardized confidence and
uncertainty is critical for optimal actionability from radio-based location
technologies. The record is clear that standardized confidence and uncertainty should
be adopted.58

x

The Commission should establish a maximum time-to-first-fix of 30 seconds for
compliance purposes.

x

The Commission should establish a process for PSAPs or State 911 Administrators to
raise concerns if they experience performance problems, once the PSAP has
demonstrated it has done its part to obtain high-accuracy location estimates, including
adoption of appropriate rebidding procedures.

CONCLUSION
T-Mobile urges the Commission to adopt new rules for location accuracy based on the

consensus Roadmap between the four nationwide carriers, APCO, and NENA. The Roadmap
establishes feasible—yet aggressive—timelines for achieving real improvement in indoor
location accuracy for wireless E911 calls, as well as establishes a path to a true dispatchable
location solution—the gold standard for public safety.
Respectfully submitted,

Commission noted, it would be reasonable to exclude calls of insufficient duration to
establish a location estimate.
57

Letter from Derek Poarch, Executive Director, APCO, Brian Fontes, CEO, NENA, and Scott
K. Bergmann, Vice President, Regulatory Affairs, CTIA, to Marlene H. Dortch, Secretary,
FCC, PS Docket No. 07-114 (Dec. 23, 2014) (submitting recommendations for confidence
and uncertainty data provided with location information).

58

See Reply Comments of ATIS, PS Docket No. 07-114, at 5-6 (July 14, 2014); Comments of
NENA, PS Docket No. 07-114, at 8-9 (May 12, 2014); Comments of the Texas 9-1-1
Entities, PS Docket No. 07-114, at 3 (May 12, 2014); Comments of T-Mobile USA, Inc., PS
Docket No. 07-114, at 21 (May 12, 2014); Comments of Qualcomm, PS Docket No. 07-114,
at 19 (May 12, 2014); Comments of NextNav, PS Docket No. 07-114, at 45 (May 12, 2014).
21

 Steve B. Sharkey
Eric Hagerson
T-MOBILE USA, INC.
601 Pennsylvania Ave., NW
Washington, DC 20004
(202) 654-5900

John T. Nakahata
Kristine Laudadio Devine
HARRIS, WILTSHIRE & GRANNIS LLP
1919 M Street, Eighth Floor
Washington, DC 20036
(202) 730-1300
Counsel to T-Mobile USA, Inc.

December 24, 2014

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