6 A-GNSS minimum performance requirements (UE supports other or additional GNSSs)

38.1713GPPNRRelease 17Requirements for Support of Assisted Global Navigation Satellite System (A-GNSS)TS

6.0 Introduction

The minimum performance requirements specified in clause 6 apply for UEs that support other A-GNSSs than GPS L1 C/A, or multiple A-GNSSs which may or may not include GPS L1 C/A. The requirements for UEs that support A-GPS L1 C/A only are specified in clause 5.

The A-GNSS minimum performance requirements are defined by assuming that all relevant and valid assistance data is received by the UE in order to perform GNSS measurements and/or position calculation. This clause does not include nor consider delays occurring in the various signalling interfaces of the network.

In the following clauses the minimum performance requirements are based on availability of the assistance data information and messages defined in annexes D and E.

6.1 Sensitivity

A sensitivity requirement is essential for verifying the performance of A-GNSS receiver in weak satellite signal conditions. In order to test the most stringent signal levels for the satellites the sensitivity test case is performed in AWGN channel. This test case verifies the performance of the first position estimate, when the UE is provided with only coarse time assistance and when it is additionally supplied with fine time assistance.

6.1.1 Coarse time assistance

In this test case 6 satellites are generated for the terminal for single constellation and dual constellation, and 7 satellites are generated for triple constellation. AWGN channel model is used.

Table 6.1: Test parameters

System

Parameters

Unit

Value

Number of generated satellites per system

–

See Table 6.2

Total number of generated satellites

–

6 or 7(2)

HDOP range

1.4 to 2.1

Propagation conditions

–

AWGN

GNSS coarse time assistance error range

seconds

±2

BDS

Reference high signal power level

dBm

-136

Reference low signal power level

dBm

-145

Galileo

Reference high signal power level

dBm

-142

Reference low signal power level

dBm

-147

GLONASS

Reference high signal power level

dBm

-142

Reference low signal power level

dBm

-147

GPS(1)

Reference high signal power level

dBm

-142

Reference low signal power level

dBm

-147

NOTE 1: "GPS" here means GPS L1 C/A, Modernized GPS, or both, dependent on UE capabilities.

NOTE 2: 7 satellites apply only for case of triple constellation.

Table 6.2: Power level and satellite allocation

Satellite allocation for each constellation

GNSS-1(1)

GNSS-2

GNSS-3

Single constellation

High signal level

1

–

–

Low signal level

5

–

–

Dual constellation

High signal level

1

–

–

Low signal level

2

3

–

Triple constellation

High signal level

1

–

–

Low signal level

2

2

2

Note 1: GNSS-1, i.e. the system having the satellite with high signal level, shall be selected by the device manufacturer.

6.1.1.1 Minimum requirements (Coarse time assistance)

The position estimates shall meet the accuracy and response time specified in Table 6.3.

Table 6.3: Minimum requirements (coarse time assistance)

System

Success rate

2-D position error

Max response time

All

95 %

100 m

20 s

6.1.2 Fine time assistance

This requirement is only valid for fine time assistance capable UEs. In this requirement 6 satellites are generated for the terminal for single constellation and dual constellation, and 7 satellites are generated for triple constellation. AWGN channel model is used.

Table 6.4: Test parameters

System

Parameters

Unit

Value

Number of generated satellites per system

–

See Table 6.5

Total number of generated satellites

–

6 or 7(2)

HDOP range

1.4 to 2.1

Propagation conditions

–

AWGN

GNSS coarse time assistance error range

seconds

±2

GNSS fine time assistance error range

s

±10

BDS

Reference signal power level

dBm

-147

Galileo

Reference signal power level

dBm

-147

GLONASS

Reference signal power level

dBm

-147

GPS(1)

Reference signal power level

dBm

-147

NOTE 1: "GPS" here means GPS L1 C/A, Modernized GPS, or both, dependent on UE capabilities.

NOTE 2: 7 satellites apply only for case of triple constellation.

Table 6.5: Satellite allocation

Satellite allocation for each constellation

GNSS-1

GNSS-2

GNSS-3

Single constellation

6

–

–

Dual constellation

3

3

–

Triple constellation

3

2

2

6.1.2.1 Minimum requirements (Fine time assistance)

The position estimates shall meet the accuracy and response time requirements in Table 6.6.

Table 6.6: Minimum requirements for fine time assistance capable terminals

System

Success rate

2-D position error

Max response time

All

95 %

100 m

20 s

6.2 Nominal accuracy

Nominal accuracy requirement verifies the accuracy of A-GNSS position estimate in ideal conditions. The primarily aim of the test is to ensure good accuracy for a position estimate when satellite signal conditions allow it. This test case verifies the performance of the first position estimate.

In this requirement 6 satellites are generated for the terminal for single constellation and dual constellation, and 7 satellites are generated for triple constellation. If SBAS is to be tested one additional satellite shall be generated. AWGN channel model is used. The number of simulated satellites for each constellation is as defined in Table 6.8.

Table 6.7: Test parameters

System

Parameters

Unit

Value

Number of generated satellites per system

–

See Table 6.8

Total number of generated satellites

–

6 or 7(2) or 8(3)

HDOP Range

–

1.4 to 2.1

Propagation conditions

–

AWGN

GNSS coarse time assistance error range

seconds

±2

BDS

Reference signal power level for all satellites

dBm

-133

Galileo

Reference signal power level for all satellites

dBm

-127

GLONASS

Reference signal power level for all satellites

dBm

-131

GPS(1)

Reference signal power level for all satellites

dBm

-128.5

QZSS

Reference signal power level for all satellites

dBm

-128.5

SBAS

Reference signal power level for all satellites

dBm

-131

NOTE 1: "GPS" here means GPS L1 C/A, Modernized GPS, or both, dependent on UE capabilities.

NOTE 2: 7 satellites apply for case of single or dual constellation and SBAS is supported or case of triple constellation and SBAS is not supported.

NOTE 3: 8 satellites apply only for case of triple constellation and SBAS is supported.

If QZSS is supported, one of the GPS satellites will be replaced by a QZSS satellite with respective signal support. If SBAS is supported, the SBAS satellite with the highest elevation will be added to the scenario.

Table 6.8: Satellite allocation

Satellite allocation for each constellation

GNSS 1(1)

GNSS 2(1)

GNSS 3(1)

SBAS

Single constellation

6

—

—

1

Dual constellation

3

3

—

1

Triple constellation

3

2

2

1

NOTE 1: GNSS refers to global systems i.e. BDS, Galileo, GLONASS, GPS.

6.2.1 Minimum requirements (nominal accuracy)

The position estimates shall meet the accuracy and response time requirements in Table 6.9.

Table 6.9: Minimum requirements

System

Success rate

2-D position error

Max response time

All

95 %

15 m

20 s

6.3 Dynamic range

The aim of a dynamic range requirement is to ensure that a GNSS receiver performs well when visible satellites have rather different signal levels. Strong satellites are likely to degrade the acquisition of weaker satellites due to their cross‑correlation products. Hence, it is important in this test case to keep use AWGN in order to avoid loosening the requirements due to additional margin because of fading channels. This test case verifies the performance of the first position estimate.

In this requirement 6 satellites are generated for the terminal for single constellation and dual constellation, and 7 satellites are generated for triple constellation. Two different reference power levels, denoted as "high" and "low" are used for each GNSS. The allocation of "high" and "low" power level satellites depends on the number of supported GNSSs and it is defined in Table 6.11. AWGN channel model is used.

Table 6.10: Test parameters

System

Parameters

Unit

Value

Number of generated satellites per system

–

See Table 6.11

Total number of generated satellites

–

6 or 7(2)

HDOP Range

–

1.4 to 2.1

Propagation conditions

–

AWGN

GNSS coarse time assistance error range

seconds

±2

BDS

Reference high signal power level

dBm

-133.5

Reference low signal power level

dBm

-145

Galileo

Reference high signal power level

dBm

-127.5

Reference low signal power level

dBm

-147

GLONASS

Reference high signal power level

dBm

-131.5

Reference low signal power level

dBm

-147

GPS(1)

Reference high signal power level

dBm

-129

Reference low signal power level

dBm

-147

NOTE 1: "GPS" here means GPS L1 C/A, Modernized GPS, or both, dependent on UE capabilities.

NOTE 2: 7 satellites apply only for case of triple constellation.

Table 6.11: Power level and satellite allocation

Satellite allocation for each constellation

GNSS 1(1)

GNSS 2(1)

GNSS 3(1)

Single constellation

High signal level

2

—

—

Low signal level

4

—

—

Dual constellation

High signal level

1

1

—

Low signal level

2

2

—

Triple constellation

High signal level

1

1

1

Low signal level

2

1

1

NOTE 1: GNSS refers to global systems i.e. BDS, Galileo, GLONASS, GPS.

6.3.1 Minimum requirements (dynamic range)

The position estimates shall meet the accuracy and response time requirements in Table 6.12.

Table 6.12: Minimum requirements

System

Success rate

2-D position error

Max response time

All

95 %

100 m

20 s

6.4 Multi-path scenario

The purpose of the test case is to verify the receiver’s tolerance to multipath while keeping the test setup simple. This test case verifies the performance of the first position estimate.

In this requirement 6 satellites are generated for the terminal for single constellation and dual constellation, and 7 satellites are generated for triple constellation. Some of the satellites have a one tap channel representing the LOS signal. The other satellites have a two-tap channel, where the first tap represents the LOS signal and the second represents a reflected and attenuated signal as specified in Annex C.2. The number of satellites generated for each GNSS as well as the channel model used depends on the number of systems supported by the UE and is defined in Table 6.14. The channel model as specified in Annex C.2 further depends on the generated signal.

Table 6.13: Test parameter

System

Parameters

Unit

Value

Number of generated satellites per system

–

See Table 6.14

Total number of generated satellites

–

6 or 7(2)

HDOP range

1.4 to 2.1

Propagation conditions

–

AWGN

GNSS coarse time assistance error range

seconds

±2

BDS

Reference signal power level

dBm

-133

Galileo

Reference signal power level

dBm

-127

GLONASS

Reference signal power level

dBm

-131

GPS(1)

Reference signal power level

dBm

-128.5

NOTE 1: "GPS" here means GPS L1 C/A, Modernized GPS, or both, dependent on UE capabilities.

NOTE 2: 7 satellites apply only for case of triple constellation.

Table 6.14: Channel model allocation

Channel model allocation for each constellation

GNSS-1

GNSS-2

GNSS-3

Single constellation

One-tap channel

2

—

—

Two-tap channel

4

—

—

Dual constellation

One-tap channel

1

1

—

Two-tap channel

2

2

—

Triple constellation

One-tap channel

1

1

1

Two-tap channel

2

1

1

6.4.1 Minimum requirements (multi-path scenario)

The position estimates shall meet the accuracy and response time requirements in Table 6.15.

Table 6.15: Minimum requirements

System

Success rate

2-D position error

Max response time

All

95 %

100 m

20 s

6.5 Moving scenario and periodic update

The purpose of the test case is to verify the receiver’s capability to produce GNSS measurements or location fixes on a regular basis, and to follow when it is located in a vehicle that slows down, turns or accelerates. A good tracking performance is essential for certain location services. A moving scenario with periodic update is well suited for verifying the tracking capabilities of an A-GNSS receiver in changing UE speed and direction. In the requirement the UE moves on a rectangular trajectory, which imitates urban streets. AWGN channel model is used. This test is not performed as a TTFF test.

In this requirement 6 satellites are generated for the terminal for single constellation and dual constellation, and 7 satellites are generated for triple constellation. The UE is requested to use periodical reporting with a reporting interval of 2 seconds.

The UE moves on a rectangular trajectory of 940 m by 1 440 m with rounded corner defined in Figure 6.1. The initial reference is first defined followed by acceleration to final speed of 100 km/h in 250 m. The UE then maintains the speed for 400 m. This is followed by deceleration to final speed of 25 km/h in 250 m. The UE then turn 90 degrees with turning radius of 20 m at 25 km/h. This is followed by acceleration to final speed of 100 km/h in 250 m. The sequence is repeated to complete the rectangle.

Table 6.16: Trajectory Parameters

Parameter

Distance (m)

Speed (km/h)

l11, l15, l21, l25

20

25

l12, l14, l22, l24

250

25 to 100 and 100 to 25

l13

400

100

l23

900

100

Figure 6.1: Rectangular trajectory of the moving scenario and periodic update test case

Table 6.17: Test Parameters

System

Parameters

Unit

Value

Number of generated satellites per system

–

See Table 6.18

Total number of generated satellites

–

6 or 7(2)

HDOP Range per system

–

1.4 to 2.1

Propagation conditions

–

AWGN

GNSS coarse time assistance error range

seconds

±2

BDS

Reference signal power level for all satellites

dBm

-133

Galileo

Reference signal power level for all satellites

dBm

-127

GLONASS

Reference signal power level for all satellites

dBm

-131

GPS(1)

Reference signal power level for all satellites

dBm

-128.5

NOTE 1: "GPS" here means GPS L1 C/A, Modernized GPS, or both, dependent on UE capabilities.

NOTE 2: 7 satellites apply only for case of triple constellation.

Table 6.18: Satellite allocation

Satellite allocation for each constellation

GNSS 1(1)

GNSS 2(1)

GNSS 3(1)

Single constellation

6

—

—

Dual constellation

3

3

—

Triple constellation

3

2

2

NOTE 1: GNSS refers to global systems i.e. BDS, Galileo, GLONASS, GPS.

6.5.1 Minimum requirements (moving scenario and periodic update)

The position estimates shall meet the accuracy requirement of Table 6.19 with the periodical reporting interval defined in Table 6.19 after the first reported position estimates.

NOTE: In the actual testing the UE may report error messages until it is able to acquire GNSS measured results or a position estimate. The test equipment shall only consider the first measurement report different from an error message as the first position estimate in the requirement in Table 6.19.

Table 6.19: Minimum requirements

System

Success rate

2-D position error

Periodical reporting interval

All

95 %

50 m

2 s

Annex A (normative):
Test cases