9. LightSquared interference issue 111611Nov 17, 2011 · Initial LightSquared Deployment: Las Vegas, Phoenix, Denver, Baltimore-Washington DC 2392 of 40000+ Towers: Aircraft at 10,000’

By: Deane Bunce, Co-Chair to National PNT Systems Engineering Forum (NPEF)

Date: November 17, 2011

Federal Aviation Administration LightSquared –

Interference Issue

2 Federal Aviation Administration

November 17, 2011 PNT Symposium – Stanford University

Overview

•  Background

•  NPEF Tasking

•  Test Methdology and Analysis Approach

•  Next Steps

2



Interference Concerns • LightSquared's “final” operating configuration

–  Interim LightSquared deployment plans (or “standstill” offers) do not protect GPS users from end-state LightSquared system

• Consideration of “All” GPS users, current and future –  Expectation that filters can resolve interference issues is largely

a potential mitigation only for future GPS receivers –  Filters will not address the tens of millions of GPS receivers in

use today –  Interference needs to be resolved for currently fielded GPS

receivers—without GPS modifications • Address interference from both ATCs and handsets

–  LightSquared user smartphones (or similar devices) transmit in the band above GPS in addition to ATC signals in the MSS band

–  Preliminary analysis indicates handset transmissions cause harmful interference in close proximity (e.g. in a car or aircraft)



Background •  January 2011 – FCC grants conditional waiver to LSQ

–  LSQ required to study potential of GPS overload interference and identify means to preclude harmful interference

–  FCC mandated Technical Working Group (TWG) be utilized •  June 2011 – TWG and NPEF Reports submitted to FCC

–  LSQ developed “signal spectral occupancy concept” mid-way through TWG testing

–  LSQ and GPS community interpretations of test results (assumptions, definitions, thresholds for ‘harmful interference’) differed significantly

•  September 2011 – FCC & NTIA request additional testing –  Cellular and General Location/Navigation Receivers constrained to LSQ

“Lower 10 MHz”, designated 10L-only –  FAA/LSQ also continuing analysis and discussion on implications for

aviation receivers (working on probabilistic path loss modeling and determination of aggregate RFI)

–  High Precision followed by GPS timing filter testing and integrated device testing once LSQ band-limiting filters are available

–  Evaluation of handset effects once LSQ units are available



Background (con’t) •  October 2011– NCO on behalf of Executive Steering Group,

tasked NPEF –  Conduct testing of General Location/Navigation devices

–  Focus only on the “first phase” of LightSquared deployment” (1526 – 1536 MHz) with simulation of LSQ handset emissions

–  Cellular Device testing •  Follow-on to TWG results for select units that were ‘inconclusive’

•  Oversight of testing handled directly by NTIA without NPEF involvement

–  Required to engage both LightSquared and GPS communities

–  Use of NTIA standard definitions and metrics to assess interference •  Interference thresholds • Propagation models

•  Antenna characteristics • Handset planning assumptions



Illustration of Concerns

GLONASS

GLONASS

1525 1559 1575 1610

Situation before LightSquared

1525 1559 1575 1610

Situation with LightSquared

low power (on Earth) satcom emissions

low power (on Earth) satcom emissions

6

Up to 15 kW base station emissions



1525 1559 1610 L Band Satellite Downlink (34 MHz) (ARNS + RNSS band )

LTE (10) (10L) LTE (10) (10H) 1526 1536 1545.2 1555.2

3.8 9.2

LTE (5) 1526.3 1531.3

LTE (5) 1550.2 1555.2

1575.42 MHz

16.42 MHz

L1

Phase 0/1

Phase 2

1525 1559 1626.5 1610

L Band Satellite (Uplink)

L Band Satellite (Downlink)

Aer

onau

tical

Te

lem

etry

Aeronautical Radio Navigation/ Radio Navigation-Satellite

(GPS, 51MHz) Big LEO (Uplink)

1660.5

LightSquared Spectral Occupancy Plans

LTE Handset

1627.5 1637.5 1646.7 1656.7



Upper L-Band Spectrum for Global Navigation Satellite Systems

8

1559 1575.42 1610 (MHz)

GPS

GLONASS

COMPASS

QZSS

GALILEO

L 1



NPEF Findings •  NPEF Assessment of LightSquared Impacts to GPS and its

Applications – June 2011 –  Phase 0, Phase 1, and Phase 2 deployments of ATC transmitters

utilizing the MSS band demonstrated detrimental impacts to all GPS applications assessed

–  Simulation results showed that completion of the Network of high-powered base stations envisioned by LightSquared would result in degradation or loss of GPS function (ranging, position) at standoff distances of a few kilometers extending to space operations

–  Possible mitigations for GPS applications were identified and evaluated but deemed impractical

•  would require significant modification or complete redesign and replacement of currently fielded GPS equipment

•  timeline to field new GPS receivers for some applications, from initial concept development through production, can take 10-15 years.

–  Certain applications, even with modification or complete redesign, would still not be able to perform their current mission in the presence of such a Network broadcasting directly adjacent to the GPS L1 band



NPEF Assessment – June 2011 (continued)   Initial LightSquared Deployment: Las Vegas, Phoenix, Denver, Baltimore-Washington DC □ 2392 of 40000+ Towers: Aircraft at 10,000’

Emissions exceed FAA TSO C145/146/196 test level (-86.4 dBm)

>1-dB SNR degradation for Receiver #2 (-64 dBm)

LightSquared base station location



Aviation Impact (Initial Deployment) Aircraft at 500’

No Position Output – Aviation Receiver “A” (-47 dBm) No Position Output – Aviation Receiver “B” (-37 dBm)

11



NPEF Tasker

•  Content based on NTIA Letter requesting ESG to conduct additional testing –  Confirm validity of prior TWG measurements collected to assess LSQ

modified proposal

–  Provide NTIA data to allow Federal Agencies to identify any additional operating restrictions needed to mitigate interference issues related to cellular and General Navigation

–  Evaluate proposed mitigation plans for high-precision and timing receivers once filtering solution available

–  Evaluate effectiveness of PCTEL antenna in mitigating interference to timing receivers without degrading performance



NPEF Test Methodology

•  Develop Comprehensive Test Plan –  Test approach, environment and receiver sets

–  Test hardware includes LightSquared supplied filter

•  Test environments Used –  Laboratory for conducted emissions

–  Anechoic chamber for radiated emissions



Conducted Emissions Testing •  Testing conducted at SPAWAR

–  September 26 to October 19

•  Test Approach –  Connect all signals directly to input of receiver filter/LNA (directly after

GPS antenna element) –  Input power level stepped (1 dB steps) using variable attenuator

•  Emulated LightSquared signals with ‘shaped’ noise –  10 MHz bandwidth noise signal(s) centered at 1531 MHz (10L)

•  Evaluations limited primarily to DoD receivers –  Testing established prior to NPEF tasking (signed out on Oct 12)



Anechoic Chamber Testing •  USAF Space Command sponsored testing conducted at White

Sands Missile Range (WSMR) •  Test Plan developed and coordinated with LightSquared

–  Testing employed use of actual LSQ antennas •  Testing invitation went out to both industry and government

–  Dates of testing: October 26 – November 4 •  Participants included several USG agencies and commercial

companies •  Testing conducted with suite of 182 GPS receivers

–  101 General Location, 52 Military and 29 High Precision •  Test conducted using emulated LightSquared handsets •  Test Limitations

–  Single LSQ ATC transmit antenna –  Could not extract all necessary data (primarily C/No data) from

some receivers



Chamber Testing Summary •  All Test Events Completed

Successfully •  Data Compilation and analysis

conducted at GPSD –  Plan to complete analysis next week

•  Results to be presented as EIRP from the LightSquared base station transmitter required to cause a 1 dB C/No degradation –  Separation distance determined via

propagation models



Other Testing and Studies •  Cellular Devices

–  Testing scheduled for next week at commercial lab/chamber

–  NTIA oversight of this testing

–  Results to be developed & presented by NTIA

•  Certified Aviation Receivers –  Not tested this round

–  FAA and LightSquared analysis in progress based upon RTCA recommended study areas, LSQ 10L deployment plan and legacy certified avionics

–  Analysis considers GPS Navigation, ADS-B surveillance, and Terrain Awareness and Warning and Systems (TAWS) for both fixed wing and helicopters



Next Steps •  Preparation of NPEF Test Report for NCO, EXCOM and NTIA/

FCC •  Scope Next LightSquared Test Phase(s)

–  High Precision and Timing Receivers (different timelines) •  Awaiting LSQ-provided High Precision and Timing filters (November

and March 2012 respectfully), antennas and handsets –  Schedule

•  Tentatively, Spring of 2012 •  Test Types – Lab; Chamber; Live Sky; Aggregate Effects

–  Test Agency/Location – TBD –  Funding – Cost Estimate; Source TBD

Documents

9. LightSquared interference issue 111611Nov 17, 2011 · Initial LightSquared Deployment: Las Vegas, Phoenix, Denver, Baltimore-Washington DC 2392 of 40000+ Towers: Aircraft at 10,000’