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Content for  TS 25.171  Word version:  16.0.0

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1  ScopeWord‑p. 6

The present document establishes the minimum performance requirements for A-GPS for FDD mode of UTRA for the User Equipment (UE).

2  References

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
TS 25.101: "User Equipment (UE) radio transmission and reception (FDD)".
TS 25.104: "Base Station (BS) radio transmission and reception (FDD)".
TS 34.171: "Terminal Conformance Specification, Assisted Global Positioning System (A-GPS) (FDD)".
TS 25.331: "Radio Resource Control (RRC) protocol specification".
TS 25.302: "Services provided by the physical layer".
TS 25.215: "Physical layer; Measurements (FDD)".
ETSI TR 102 273-1-2: "Electromagnetic compatibility and Radio spectrum Matters (ERM); Improvement on Radiated Methods of Measurement (using test site) and evaluation of the corresponding measurement uncertainties; Part 1: Uncertainties in the measurement of mobile radio equipment characteristics; Sub-part 2: Examples and annexes".
Navstar GPS Space Segment/Navigation User Interfaces, ICD-GPS 200, Rev. C.
P. Axelrad, R.G. Brown, "GPS Navigation Algorithms", in Chapter 9 of "Global Positioning System: Theory and Applications", Volume 1, B.W. Parkinson, J.J. Spilker (Ed.), Am. Inst. of Aeronautics and Astronautics Inc., 1996.
S.K. Gupta, "Test and Evaluation Procedures for the GPS User Equipment", ION-GPS Red Book, Volume 1, p. 119.
TS 34.109: "Special conformance testing functions"

3  Definitions, symbols, abbreviations and test tolerancesWord‑p. 7

3.1  Definitions

For the purposes of the present document, the terms and definitions given in TS 25.101, TS 25.104 and the following apply:
Horizontal Dilution Of Precision (HDOP):
measure of position determination accuracy that is a function of the geometrical layout of the satellites used for the fix, relative to the receiver antenna
Node B:
logical node responsible for radio transmission / reception in one or more cells to/from the User Equipment. Terminates the Iub interface towards the RNC
L band GPS transmission frequency of 1575.42 MHz

3.2  Symbols


3.3  Abbreviations

For the purposes of the present document, the following abbreviations apply:
Assisted - Global Positioning System
Additive White Gaussian Noise
Common Pilot CHannel
Dedicated CHannel
Dedicated Physical CHannel
Device Under Test
Earth Centred, Earth Fixed
Fast Access CHannel
Frequency Division Duplex
Global Positioning System
GPS System Simulator
Horizontal Dilution Of Precision
Line Of Sight
Paging Indicator CHannel
Radio Resource Control
Received Signal Code Power
System Frame Number
Standalone Mobile Location Center
Serving Radio Network Controller
FDD System simulator
Time Division Duplex
TeLeMetry word. It contains an 8-bits preamble (10001011)
Time Of Week
Time To First Fix
User Equipment
Universal Terrestrial Radio Access
Universal Terrestrial Radio Access Network
Weighted Least Square

3.4  Test tolerancesWord‑p. 8

The requirements given in the present document make no allowance for measurement uncertainty. The test specification 3GPP TS 34.171 [3] defines test tolerances. These test tolerances are individually calculated for each test. The test tolerances are then added to the limits in the present document to create test limits. The measurement results are compared against the test limits as defined by the shared risk principle.
Shared Risk is defined in ETR 273-1-2 [7], subclause 6.5.

4  General

4.1  Introduction

The present document defines the minimum performance requirements for both UE based and UE assisted FDD A GPS terminals.

4.2  Measurement parameters

4.2.1  UE based A-GPS measurement parameters

In case of UE-based A-GPS, the measurement parameters are contained in the RRC UE POSITIONING POSITION ESTIMATE INFO IE. The measurement parameter in case of UE-based A-GPS is the horizontal position estimate reported by the UE and expressed in latitude/longitude.

4.2.2  UE assisted A-GPS measurement parameters

In case of UE-assisted A-GPS, the measurement parameters are contained in the RRC UE POSITIONING GPS MEASURED RESULTS IE. The measurement parameters in case of UE-assisted A-GPS are the UE GPS Code Phase measurements, as specified in TS 25.302 and TS 25.215. The UE GPS Code Phase measurements are converted into a horizontal position estimate using the procedure detailed in Annex F.

4.3  Response time

Max Response Time is defined as the time starting from the moment that the UE has received the final RRC measurement control message containing reporting criteria different from "No Reporting" sent before the UE sends the measurement report containing the position estimate or the GPS measured result, and ending when the UE starts sending the measurement report containing the position estimate or the GPS measured result on the Uu interface. The response times specified for all test cases are Time-to-First-Fix (TTFF) unless otherwise stated, i.e. the UE shall not re use any information on GPS time, location or other aiding data that was previously acquired or calculated and stored internally in the UE. A dedicated test message 'RESET UE POSITIONING STORED INFORMATION' has been defined in TS 34.109 clause 5.4 for the purpose of deleting this information and is detailed in subclause B.1.10.

4.4  Time assistance

Time assistance is the provision of GPS time to the UE from the network via RRC messages. Currently two different GPS time assistance methods can be provided by the network.
  1. Coarse time assistance is always provided by the network and provides current GPS time to the UE. The time provided is within ±2 seconds of GPS system time. This allows the GPS time to be known within one GPS navigation data sub-frame. It is signalled to the UE by means of the GPS Week and GPS TOW msec fields in the Reference Time assistance data IE.
  2. Fine time assistance is optionally provided by the network and adds the provision to the UE of the relationship between the GPS system time and the current UTRAN time. The accuracy of this relationship is ±10 μs of the actual relationship. This addresses the case when the network can provide an improved GPS time accuracy. It is signalled to the UE by means of the SFN and UTRAN GPS timing of cell frames fields in the Reference Time assistance data IE.
The time of applicability of time assistance is the beginning of the System Frame of the message containing the GPS Reference time.

4.4.1  Use of fine time assistanceWord‑p. 9

The use of fine time assistance to improve the GPS performance of the UE is optional for the UE, even when fine time assistance is signalled by the network. Thus, there are a set minimum performance requirements defined for all UEs and additional minimum performance requirements that are valid for fine time assistance capable UEs only. These requirements are specified in subclause 5.1.2.

4.5  RRC states

The minimum A-GPS performance requirements are specified in clause 5 for different RRC states that include Cell_DCH and Cell_FACH. Cell_PCH and URA_PCH states are for further study. The test and verification procedures are separately defined in annex B.

4.6  2D position error

The 2D position error is defined by the horizontal difference in meters between the ellipsoid point reported or calculated from the UE Measurement Report and the actual position of the UE in the test case considered.

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