E-911 Enhancement Solutions

Transcription

1 Indoor Wireless Accuracy: E-911 Enhancement Solutions Impacts on In-Building Distributed Antenna Systems Skip Crilly Cellular Specialties, Inc.

2 Topics What is E-911? How are E-911 calls located? FCC-mandated d location accuracies FCC-led activities to improve accuracy Issues with indoor location accuracy New technologies that improve indoor position accuracy

3 Indoor Subscribers Wireless devices are the number one means of communications today 70 percent of voice calls and 80 percent of data sessions occur indoors Most tlarge buildings and campuses require (a)dedicated di dsystem(s) to ensure ubiquity of: Cellular Public safety WiFi services Thousands of distributed antenna system (DAS) nodes and repeaters are installed at hundreds of higher education institutions in the United States (E-911 LOCATION technology rarely evaluated!) Sponsored by Cellular Specialties, Inc.

4 Mobile Subscribers Dominate System According to FCC, about 455,000 of the 650, calls made every day are from wireless phones wireless e911 calls landline e911 calls Many homes and apartments no longer use landlines Sponsored by Cellular Specialties, Inc.

5 How is a wireless 911 call located? Present Solutions to E911 Positioning GPS satellite signals are received and reported to the network CDMA downlink signals from cell sites are measured by the calling device and reported by the device to the network GSM uplink signals from the E-911 device are measured by, and reported, using location measurement units (LMUs) Serving cell site identification is reported to the network, as a backup report Each operator s cellular network provides a 911 call location fix to the public safety answering point (PSAP)

6 E-911 Positioning Systems are Different From Commercial Location Based Services Applications Smarter phones have more commercial app capability but E-911 positioning has to work with all devices Commercial Location Engines Google, Apple Measurements commercial applications WiFi signals are used Measurements E-911 system WiFi signals are not used

7 History of E-911 E-911 = Enhanced FCC docket opened in (94-102) within five years, requires accuracy of 125m RMS Separate handset and network-based rules adopted 50m CDMA, (x2 GSM) for 67 percent of calls 150m CDMA, (x2 GSM) for 95 percent of calls 2012 FCC indoor location accuracy initiative Future: Next Gen = NG911

8 History of E-911 Continued FCC opens new docket in 2007 (07-114) to update rules January broad changes made to the phase II rules Accuracy is to be measured at PSAP or county boundary level New rules are being phased in over the rest of the decade such that all service providers will be required to provide 50 meter accuracy 67 percent of the time, and 150 meter accuracy 90 percent of the time, in 90 percent of the counties nationwide Indoor location accuracy investigation Sponsored by Cellular Specialties, Inc.

9 911 Calls Need Indoor Location No FCC requirement exists for indoor testing. Dormitories, parking garages, office areas, commons, class rooms, arenas, stadiums and other GPS - denied venues can fit into the ten percent exclusion zone of the 150m 90 percent (to be 95 percent) mandate The current FCC requirements will leave a university campus vulnerable to large position errors in the places likely to be in need of assistance

10 FCC Activities: Indoor Location Accuracy The FCC has given a CSRIC working group the goal of investigating new technologies, and reporting indoor E-911 location accuracy ~40 experts from industry and carriers are in the CSRIC working group An indoor test-bed is underway at several locations in northern California participants: Qualcomm/Verizon AFLT, MCS, A-GPS NextNav 900 MHz LMS Boeing Iridium Polaris RF Fingerprinting Future: WiFi beacons and others for future discussion CSRIC = communications, i security, reliability, interoperability council

11 A 911 caller s device receives many signals Not all signals are used for E-911 Green = Currently used for E-911 LMU = Location measurement unit GPS 900 MHz FCC LMS FCC Location & Monitoring Service Glonass Glonass GPS Iridium CDMA CDMA WiFi 911 GSM LTE CDMA LMU WCDMA LMU

12 GSM and CDMA Systems Use different positioning methods GSM service providers (e.g. AT&T) use uplink measurements of cell phone transmissions to determine E-911 position solution U-TDOA is the standard technique: cell phone signals are measured at BTS (True Position, Inc.) Location measurement units (LMU s) measure relative uplink signal delays CDMA service providers (e.g. Verizon) use downlink measurements of base stations and GPS satellite transmissions to determine E-911 solutions A-GPS is part of the 911 solution. A-GPS = Assisted GPS AFLT is the terrestrial technique: BTS signals are measured at the cell phone (Qualcomm, Inc.). AFLT = advanced forward link trilateration Use CDMA Pilot signals in CDMA carrier for measurements The caller s device measures relative downlink signal delays

13 The Indoor E-911 Positioning Issue Issue: Indoor E-911 calls often cannot be located accurately, because: GPS satellite signals may be blocked in urban canyons GPS satellite signals do not penetrate many building structures Indoor distributed antenna systems can degrade position accuracy

14 Issue : Position accuracy degrades due to in-building distributed antenna system 911 Repeater antenna Basestation RF over fiber to another building 911 Where is the 911 call originating from? Relative signal delays appear the same at each building.

15 Repeaters Compounding Problems Signals re-promulgated are delayed by several microseconds, distorting measurements by thousands of feet. BTS signals used for positioning require much lower SINR than those needed for communication, therefore some non repeated signals are heard which can result in a pathologic condition: Some signals are delayed, others not. DAS Environments Operational paradigm forbids use of measurements from BTS signals that go through fiber. (Not Line of Sight and velocity only 0.6 c). Operational paradigm forbids measurements from BTS signals that are ambiguous due to simulcasting. Geometric techniques, e.g. signal strength measurements, are compromised due to inability of tools to model small or oddly shaped DAS coverage footprints. Sponsored by Cellular Specialties, Inc.

16 A Repeater s Effect on Position Measurements Repeater s 3 microseconds of delay => ~1000 yards of measurement error. Real Distance Repeater Perceived Distance based on measured time of arrival through repeater O-DAS and I-DAS deployments have similar effects on perceived subscriber location due to delays caused by fiber routing and physics of the glass Sponsored by Cellular Specialties, Inc. 16

17 DAS Simulcasting to Multiple Buildings Measurements from BTS Building 5/6 Disqualified; Subscribers in Building 1 & 2 Indistinguishable Building 2 Building 1 Building 3/4 BTS / HE Sponsored by Cellular Specialties, Inc. 17

18 Are there existing solutions to these problems? Yes. Add additional network elements Use additional traffic sectors of a network to localize li coverage to particular buildings Add location measurement units in GSM/WCDMA networks Both of these solutions add complexity to the network. Add additional signals using beacons The additional signals are unique to a venue A CDMA co-pilot beacon (CPB) is a technology that has existing network compatibility and is cost-effective Sponsored by Cellular Specialties, Inc.

19 Co-Pilot Beacon Deployment for Repeater Covered Venue Co-Pilot Beacon Beacon coverage footprint is small. If you can hear me, you must be near me! The CDMA network s Base Station Almanac uses the beacon location and contains a building-footprint size metric. Sponsored by Cellular Specialties, Inc. 19

20 Co-Pilot Beacons provide additional distance references Co-Pilot Beacon PN2 PN1 T1 GPS T2 DAS coverage indoors BTS or off-air repeater feeds a distributed antenna system PN5 Macro outdoors PN4 T4 Device requiring position info T3 PN3

21 CPB signals are summed into a distributed antenna system How to sum CPB signals into traffic channels Inject tcpb signal at tlow power at tthe host units Inject CPB signal at low power before PA at DAS remote unit Inject CPB signal into DAS server antenna Or, sum digital signal if digital media Directional coupler Head end Host unit(s) i() From BTS or repeater Fiber or other media N or coax Remote unit(s) i() 21

22 Some aspects of Co-Pilot Beacons CPBs are not proprietary technology CPBs are currently supplied by multiple equipment vendors No change is required to the existing E-911 control plane interface standards for operation Current/future handset and smart-phone CDMA chipsets are compatible without modification CPB locations are known and entered for accurate positioning, managed as a network element Periodic surveys are not required to ensure beacon location integrity

23 McCarran Airport Situation, Goal, and Solution Situation: After the McCarran Airport DAS is installed in concourses A and B, the PSAP will not be able to adequately differentiate between 911 calls made from concourse Aorconcourse B, due to the simul-casting of a sector to both concourses Goal : Afirst responder needs to have increased confidence which concourse the call is originating from Solution: Install co-pilot beacons based on the DAS design and the design goal Identify the concourse with very high certainty

24 DAS Deployed without Co-Pilot Beacons (100 Test calls) X Sponsored by Cellular Specialties, Inc.

25 Typical Metropolitan Airport w/ DAS Deployed 1000 test calls Objective is 95% of fixes within 150 meters 25% of the fixes were outside the 1/4 mile radius 50% of the fixes were between 150 m & 1/4 mile radius Test location X 25% of the fixes 25% of the fixes were inside the 150 m radius

26 The position uncertainty is caused by the simulcasting of the BTS into the DAS BTS/HE Sponsored by Cellular Specialties, Inc. 26

27 DAS Deployed With Beacons (100 test points) X Sponsored by Cellular Specialties, Inc.

28 Typical Metropolitan Airport after Co-Pilot Beacon Installation Objective of 95% of fixes within 150 meters is achieved Test location X Sponsored by Cellular Specialties, Inc.

29 Some Issues when adding beacons to indoor DAS infrastructure It is possible that the wireless network will not be able to provide the new PN codes needed d by the beacons, due to code exhaustion The wireless network needs its databases to reflect the beacons locations Solution : A multi-pn co-pilot beacon PN = Pseudo-Noise: a code used to identify a CDMA transmitter

30 Multi-PN CDMA Co-Pilot Beacon Description Multiple PNs are transmitted simultaneously on multiple existing macro 1xRTT channels Beacon pilot PN offsets are chosen to match nearby macro cell-site PN offsets, rather than use new PNs Beacon transmit delays (taus) are adjusted to match expected delays from macro sites to fix location The solution brings the macro network s positioning capability into the venue

31 A Multi-PN Co-Pilot Beacon Tau_PN1 = T1 Tau_PN2 = T2 Tau_PN3 = T3 Tau_PN4 = T4 Tau_PN5 = T4 Etc. PN1 Multi-PN Co-Pilot Beacon GPS PN2 Benefits: -No BTS database entries -No BSA database entries T1 -Moveable fix using CPB taus -Adjust taus for best accuracy PN5 PN4 T4 T3 BTS or off-air repeater T2 DAS space inside Macro space outside PN3

32 Multi-PN CDMA Co-Pilot Beacon Benefits PNs do not have to be dedicated to pilot beacons No PN exhaustion Base station almanac entries are not required for multi-pn CPB transmitters Neighbor lists generally do not have to change Low risk of neighbor list exhaustion Position fixes may be adjusted using beacon tau settings

33 Babson College Multi-PN Beacon E911 Tests Pre-Fixes Indoor DAS On/Off Beacons Off Fixes with the DAS ON -Off-air Repeater located in bldg. other side of campus Fixes with the DAS OFF 5 km High percentage of outliers

34 Babson College Multi-PN Beacon E911 Tests Pre-fixes Indoor; DAS On ; Beacons On One outlier of ~40 E911 tests Additional successful Multi-PN Tests: -Rockingham Mall -CSI lab/screen room E911 test location 250 m

35 Review Position determination for E-911/public safety is more problematic indoors than outdoors Coverage and capacity enhancements adversely impact location accuracy Smart phone apps do not currently help the public safety E-911 system Exceptions to the E-911 FCC mandate are sufficient today to account for in-building positioning errors When indoor subscribers have sufficient reference points, location accuracies are much improved Sponsored by Cellular Specialties, Inc.

36 Advice for a Safer Venue If you are deploying a DAS and/or repeater solutions for coverage, be concerned about the impact on E-911 positioning: A COMPLETED CALL IS NOT ENOUGH Augmentation equipment is considered generally available by WSPs. Request its deployment as part of the DAS solution and test it Engage systems integrators with subject matter expertise who are willing to work with the customer, WSPs, PSAPs to engineer in-building location solutions YOUR VENUE WILL BE SAFER WHEN FIRST RESPONDERS KNOW WHERE TO GO! Sponsored by Cellular Specialties, Inc.

37 Thank You! Questions? William J. (Skip) Crilly Jr. CTO Cellular Specialties, Inc. (603)