Transcript
The Wort Hotel Jackson Hole, WY February 22 - 25, 2000
TR45.3.6/00.02.22.22 Time Division Digital Technology Mobile and Personal Communications Standards
Title Stage One for System Assisted Mobile Positioning through Satellite (SAMPS)
Source Ericsson
Abstract This contribution provides the stage one for the System Assisted Mobile Positioning through Satellite (SAMPS).
Recommendation Adopt the contribution as stage one for System Assisted Mobile Positioning through Satellite (SAMPS).
NOTICE: © 2000 Telefonaktiebolaget LM Ericsson. The contributor grants a free, irrevocable license to the Telecommunications Industry Association (TIA) to incorporate text or other copyrightable material contained in this contribution and any modifications thereof in the creation of a TIA standards publication; to copyright and sell in TIA's name any TIA standards publication even though it may include portions of this contribution; and at TIA's sole discretion to permit others to reproduce in whole or in part such contributions or the resulting TIA standards publication. This contributor will also be willing to grant licenses under such copyrights to third parties on reasonable, non-discriminatory terms and conditions, if appropriate. This contribution has been prepared by Ericsson to assist the TIA TR45.3 standards subcommittee. This document should not be construed as a binding proposal on Ericsson. Specifically, Ericsson reserves the right to modify, amend, or withdraw the contents of this contribution
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Stage 1 for System Assisted Mobile Positioning through Satellite (SAMPS) 1.0 System Assisted Mobile Positioning through Satellite (SAMPS) 1.1 Background GPS-equipped handsets offer many opportunities for the network operator to offer value to the consumer through additional location-based services and applications. GPS also is suitable for public safety (E911) applications in many environments, although it is very unlikely that the coverage footprint will be truly universal even with network assistance. Within the coverage footprint, however, GPS with differential corrections (DGPS) provides superior accuracy, typically on the order of 5-10 m (RMS).
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One drawback with traditional GPS-based positioning is poor link margin. Since the satellite signals are relatively weak, GPS receivers cannot tolerate much path loss or attenuation. This reduces the footprint of GPS coverage, especially in challenging environments such as indoors and urban canyons. However, integrating a GPS receiver into a cellular handset opens many new possibilities. If the cellular network provides side information (“assistance”) to the GPS-equipped handset via the communication channel, then the GPS receiver’s sensitivity and measurement latency can be improved significantly. This allows the GPS-equipped handset to operate in challenging propagation environments where traditional, stand-alone GPS receivers cannot.
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SAMPS Assistance Options
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There are several kinds of “assistance” that the TIA/EIA-136 network can provide in order to enhance the performance of the GPS-equipped MS. There are two different general models of operation. One option where the Position Computation Function (PCF) is located in the MS and one where it is located in the Network (NW):
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1. MS-Assisted GPS (PCF in NW)
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2. MS-Based GPS with NW assistance (PCF in MS)
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MS-Assisted GPS (PCF in NW)
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The mobile-assisted solution shifts many of the traditional GPS receiver functions to the network processor. This method requires an antenna, RF section, and digital processor for making measurements by generating replica codes and correlating them with the received GPS signals. The network transmits an assistance message to the mobile station (MS), including time, visible satellite list, satellite signal Doppler, and code phase. These parameters help the embedded GPS sensor reduce the GPS acquisition time considerably. These assistance data are valid for a limited time. The MS returns the pseudorange data processed by the GPS sensor. After
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receiving the pseudorange data, the corresponding network processor or location server estimates the position of the MS. The differential correction can be applied to the final result at the network side to improve the position accuracy.
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MS-Based GPS with NW assistance (PCF in MS)
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The MS-based solution maintains a fully functional GPS receiver in the MS. This method requires the same function as MS-assisted GPS, plus an additional means for computing the satellite position and ultimately the MS position. In the initial start-up scenario, more data must be provided to the MS than for the MS-assisted case. However, this data is valid for four hours or more and can be updated as necessary over time. Typical transmissions include time, reference location, and satellite ephemeris and clock corrections. If better position accuracy is required for certain applications, DGPS data must be transmitted to the MS frequently (approximately every 30 seconds). Since the DGPS data is valid for a large geographical area, one centrally located reference receiver can be used to service this large region. The final position of the MS is generated at the MS itself. The calculated MS location can then be sent to an application outside of the MS if required.
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SAMPS Goals
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The main goal of SAMPS is to provide a handset-based platform to enable service providers to offer value-added, location-based services. SAMPS addresses subscriber-positioning requirements in TIA/EIA-136-based networks by utilizing the existing Global Positioning System (GPS) infrastructure. A secondary goal is that SAMPS should be one possible technology to fulfil the FCC E911 positioning requirements [1]. From a technology perspective, the main goal of SAMPS is to utilize the data capabilities of TIA/EIA-136 networks to enhance the performance of GPS-equipped handsets. Compared to conventional GPS receivers, this performance enhancement should be in terms of both coverage and latency or timeto-first-fix (TTFF).
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1.2
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Requirements
This section discusses the requirements and objectives of the SAMPS service. These requirements can be divided into the following categories: Requirements related to the performance of the SAMPS-capable terminals; Requirements related to the network and messages necessary to support SAMPS; Requirements related to applications that request position information from SAMPS terminals.
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The following are the requirements and objectives of the SAMPS service. Requirements are stated in terms of “shall” while objectives are stated as “should”.
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The requirements for SAMPS are as follows:
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1. The SAMPS service shall be based on a well-defined client-server model. SAMPS functional entities such as client, server, and application shall be clearly defined.
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2. The SAMPS service shall be based on a well-defined messaging protocol.
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3. The SAMPS service shall not place an undue burden on the system resources such as MSC, BS, terminal etc. 4. The SAMPS service shall allow an application to requests a mobile station’s position information at a specified QoS. The mobile station shall be able to allow or deny this request. At a minimum, this QoS should be based on latency and position accuracy. 5. The user of a SAMPS terminal shall have the capability of setting privacy options to choose which application can request its location information. Applications shall be capable of subscribing to the SAMPS’ location services whereby the location information from SAMPS terminals is provided to the requesting application, provided the applications requesting information from SAMPS-capable terminals meet the associated privacy requirement set by the terminal. 6. The SAMPS service shall be available by subscription to users with SAMPScapable terminals. 7. The SAMPS service shall be specified for both broadcast bearers and point-topoint bearers. Any assistance information with frequent payload changes that is provided on a broadcast bearer shall be configured as a stream service. Any bearer used for SAMPS should be able to deliver the assistance information in a timely manner to SAMPS terminals. For instance, satellite ephemeris information requires 18-30 seconds to demodulate from the satellite signals. In order to be of value, the SAMPS service should deliver this information much more quickly. 8. The SAMPS service shall provide assistance information to SAMPS terminals that improves the performance of such terminals compared to standalone GPS receivers. In other words, the assistance information shall enable the SAMPS terminals to provide a higher QoS to location applications. 9. The SAMPS service shall include an option for delivering differential GPS (DGPS) corrections to SAMPS terminals. 10. The SAMPS service shall have the necessary provisions to support synchronized TIA/EIA-136 networks. A TIA/EIA-136 network that is synchronized to GPS time has a fixed relationship between absolute GPS time and the air-interface time base. This relationship information may be provided as part of the SAMPS assistance, if so, the SAMPS terminal may determine GPS time from the base station air-interface rather than from the satellite signals.
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11. For unsynchronized networks, the SAMPS network model and messaging shall include provisions for mobile stations that observe air-interface timing and relate it to the GPS time base. Where available, these mobile stations may provide the cell timing information to a SAMPS teleservice server.
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12. The SAMPS service shall have no impact on existing teleservices.
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13. The SAMPS service should have no impact on the TIA/EIA-41 network.
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14. The SAMPS service shall have no impact on layers 3 and higher protocols, other than new messages that are required to deliver the assistance information.
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15. Support for SAMPS in the handset shall be optional.
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16. If a handset supports SAMPS, one of the following options shall be supported:
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MS-Based or;
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MS-Assisted or;
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MS-Based and MS-Assisted.
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17. It shall be possible to fulfil the FCC E911 requirements with the use of SAMPS. 18. SAMPS shall leverage the work done for GSM Location Services to facilitate GSM/TDMA convergence.
1.3 Normal Procedure with Successful Outcome This section lists normal procedures to be followed which result in a successful outcome. Authorization
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SAMPS may be generally available or may be provided after prearrangement with the service provider.
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SAMPS may be authorized for the following options:
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The following MS privacy options shall exist and shall apply to positioning requests to a Target MS that was not initiated by itself (except as may be overridden by FCC regulatory requirements). They define the particular classes of applications, for which a positioning is allowed, with the following classes being possible:
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(a) Universal Class – allow positioning by all applications
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(b) Subscriber Initiated Class – allow positioning by any application to which the MS originated a service that is currently established
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(c) Non-Subscriber Initiated Class – allow positioning by specific identified application or groups of applications
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(d) Operator Class – allow positioning by specific OAM&P applications within the serving system
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De-Authorization
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SAMPS may be withdrawn at the subscriber’s request or for administrative reasons.
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Registration
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SAMPS has no registration.
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De-Registration
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SAMPS has no de-registration.
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Activation
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SAMPS shall be activated upon authorization.
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De-Activation
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SAMPS shall be de-activated upon de-authorization.
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Invocation
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SAMPS may be invoked by the subscriber or by the network.
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Normal Operation with Successful Outcome
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In normal operation SAMPS may be invoked by an application for a Target MS that is operating on a DCCH or a DTC. The positioning client shall receive the position information subject to the mobile stations privacy options.
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1.4
Exception Procedures or Unsuccessful Outcome
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This section lists some of the more probable abnormal situations not described in the Normal Procedures with Successful Outcome.
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Registration None identified.
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De-Registration None identified.
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Authentication None identified.
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Activation None identified.
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De-Activation None identified.
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Invocation None identified. Exception While Roaming None identified. Exception During Inter-System Hand-off An inter-system handoff (to and from DTC) shall not prevent SAMPS from working.
1.5 Alternate Procedures None Identified.
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1.6 Interactions with Other Services Call Delivery (CD)
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None identified.
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Call Forwarding-Busy (CFB)
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None identified.
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Call Forwarding-Default (CFD) None identified. Call Forwarding-No Answer (CFNA) None identified. Call Forwarding-Unconditional (CFU) None identified. Call Transfer (CT) None identified. Call Waiting (CW) None identified. Call Number identification Presentation (CNIP) None identified. Call Number Identification Restriction (CNIR) None identified. Conference Calling (CC) None identified. Do Not Disturb (DND) None identified.
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Emergency Service If SAMPS constitutes part of an operator’s E911 service, then SAMPS shall be supported during Emergency Service calls. Flexible Alerting (FA) None identified. Message Waiting Notification (MWN) None identified. Mobile Access Hunting (MAH) None identified. Password Call Acceptance (PCA) None identified. Preferred Language (PL) None identified. Priority Access and Channel Assignment (PACA) None identified. Remote Feature Control (RFC) None identified. Selective Call Acceptance (SCA) None identified. Subscriber PIN Access (SPINA) None identified. Three-way Calling (3WC) None identified. Voice Message Retrieval (VMR)
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None identified. Voice Privacy (VP) None identified. Asynchronous Data Service (ADS) None identified. Calling Name Presentation (CNAP) None identified. Data Privacy (DP) None identified. Emergency Services Callback (9-1-1CB)
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None identified.
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Emergency Services Reconnect (9-1-1RC)
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None identified.
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Group 3 Facsimile Service (G3FAX) None identified. Incoming Call Screening (ICS) None identified. Non-Public Mode Service (NPM) None identified. Over-the-Air Service Provisioning (OTASP) None identified. Speech Option Selection (SOS) None identified.
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User Group ID (UGID) None identified.
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Voice Controlled Services (VCS) None identified.
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References 1. Third Report and Order: “Revision of the Commission’s Rules to Ensure Compatibility with Enhanced 911 Emergency Calling Systems”. Adopted September 15, 1999. FCC 99-245. CC Docket No. 94-102 RM-8143.
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