M.2 A-GPS minimum performance requirements
3GPP45.005GSM/EDGE Radio transmission and receptionTS
The A-GPS minimum performance requirements are defined by assuming that all relevant and valid assistance data is received by the MS in order to perform GPS 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 subclauses the minimum performance requirements are based on availability of the assistance data information and messages defined in clauses M.5 and M.6.
M.2.1 Sensitivity
A sensitivity requirement is essential for verifying the performance of A-GPS 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 MS is provided with only coarse time assistance and when it is additionally supplied with fine time assistance.
M.2.1.1 Coarse time assistance
In this test case 8 satellites are generated for the terminal. AWGN channel model is used.
Table M.2-1: Test parameters
|
Parameters |
Unit |
Value |
|---|---|---|
|
Number of generated satellites |
– |
8 |
|
HDOP Range |
– |
1.1 to 1.6 |
|
Propagation conditions |
– |
AWGN |
|
GPS Coarse time assistance error range |
seconds |
2 |
|
GPS Signal for one satellites |
dBm |
-142 |
|
GPS Signal for remaining satellites |
dBm |
-147 |
M.2.1.1.1 Minimum Requirements (Coarse time assistance)
The position estimates shall meet the accuracy and response time specified in table M.2-2.
Table M.2-2: Minimum requirements (coarse time assistance)
|
Success rate |
2-D position error |
Max response time |
|---|---|---|
|
95 % |
100 m |
20 s |
M.2.1.2 Fine time assistance
This requirement is only valid for fine time assistance capable MSs. In this requirement 8 satellites are generated for the terminal. AWGN channel model is used.
Table M.2-3: Test parameters for fine time assistance capable terminals
|
Parameters |
Unit |
Value |
|---|---|---|
|
Number of generated satellites |
– |
8 |
|
HDOP Range |
– |
1.1 to 1.6 |
|
Propagation conditions |
– |
AWGN |
|
GPS Coarse time assistance error range |
seconds |
2 |
|
GPS Fine time assistance error range |
s |
10 |
|
GPS Signal for all satellites |
dBm |
-147 |
M.2.1.2.1 Minimum Requirements (Fine time assistance)
The position estimates shall meet the accuracy and response time requirements in table M.2-4.
Table M.2-4: Minimum requirements for fine time assistance capable terminals
|
Success rate |
2-D position error |
Max response time |
|---|---|---|
|
95 % |
100 m |
20 s |
M.2.2 Nominal Accuracy
Nominal accuracy requirement verifies the accuracy of A-GPS 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 8 satellites are generated for the terminal. AWGN channel model is used.
Table M.2-5: Test parameters
|
Parameters |
Unit |
Value |
|---|---|---|
|
Number of generated satellites |
– |
8 |
|
HDOP Range |
– |
1.1 to 1.6 |
|
Propagation conditions |
– |
AWGN |
|
GPS Coarse time assistance error range |
seconds |
2 |
|
GPS Signal for all satellites |
dBm |
-130 |
M.2.2.1 Minimum requirements (nominal accuracy)
The position estimates shall meet the accuracy and response time requirements in table M.2-6.
Table M.2-6: Minimum requirements
|
Success rate |
2-D position error |
Max response time |
|---|---|---|
|
95 % |
30 m |
20 s |
M.2.3 Dynamic Range
The aim of a dynamic range requirement is to ensure that a GPS 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. AWGN channel model is used.
Table M.2-7: Test parameters
|
Parameters |
Unit |
Value |
|---|---|---|
|
Number of generated satellites |
– |
6 |
|
HDOP Range |
– |
1.4 to 2.1 |
|
GPS Coarse time assistance error range |
seconds |
2 |
|
Propagation conditions |
– |
AWGN |
|
GPS Signal for 1st satellite |
dBm |
-129 |
|
GPS Signal for 2nd satellite |
dBm |
-135 |
|
GPS Signal for 3rd satellite |
dBm |
-141 |
|
GPS Signal for 4th satellite |
dBm |
-147 |
|
GPS Signal for 5th satellite |
dBm |
-147 |
|
GPS Signal for 6th satellite |
dBm |
-147 |
M.2.3.1 Minimum requirements (dynamic range)
The position estimates shall meet the accuracy and response time requirements in table M.2-8.
Table M.2-8: Minimum requirements
|
Success rate |
2-D position error |
Max response time |
|---|---|---|
|
95 % |
100 m |
20 s |
M.2.4 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 5 satellites are generated for the terminal. Two of the satellites have one tap channel representing Line-Of-Sight (LOS) signal. The three other satellites have two-tap channel, where the first tap represents LOS signal and the second reflected and attenuated signal as specified in Case G1 in subclause M.4.2.
Table M.2-9: Test parameters
|
Parameters |
Unit |
Value |
|---|---|---|
|
Number of generated satellites (Satellites 1, 2 unaffected by multi-path) (Satellites 3, 4, 5 affected by multi-path) |
– |
5 |
|
GPS Coarse time assistance error range |
seconds |
2 |
|
HDOP Range |
– |
1.8 to 2.5 |
|
Satellite 1, 2 signal |
dBm |
-130 |
|
Satellite 3, 4, 5 signal |
dBm |
LOS signal of -130 dBm, multi-path signal of -136 dBm |
M.2.4.1 Minimum Requirements (multi-path scenario)
The position estimates shall meet the accuracy and response time requirements in table M.2-10.
Table M.2-10: Minimum requirements
|
Success rate |
2-D position error |
Max response time |
|---|---|---|
|
95 % |
100 m |
20 s |
M.2.5 Moving scenario and periodic location
This test case only applies to MSs supporting Rel-7 or later Supplementary Services.
The purpose of the test case is to verify the receiver’s capability to produce GPS 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 a certain location services. A moving scenario with periodic location is well suited for verifying the tracking capabilities of an A-GPS receiver in changing MS speed and direction. In the requirement the MS moves on a rectangular trajectory, which imitates urban streets. AWGN channel model is used. This test is not performed as a Time to First Fix (TTFF) test.
In this requirement 5 satellites are generated for the terminal. The MS is requested to use periodic location reporting with a reporting interval of 2 seconds.
The MS moves on a rectangular trajectory of 940 m by 1 440 m with rounded corner defined in figure M.2-1. The initial reference is first defined followed by acceleration to final speed of 100 km/h in 250 m. The MS then maintains the speed for 400 m. This is followed by deceleration to final speed of 25 km/h in 250 m. The MS 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 M.2-11: 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 M.2-1: Rectangular trajectory of the moving scenario and periodic location test case
Table M.2-12: Test Parameters
|
Parameters |
Unit |
Value |
|---|---|---|
|
Number of generated satellites |
– |
5 |
|
HDOP Range |
– |
1.8 to 2.5 |
|
Propagation condition |
– |
AWGN |
|
GPS signal for all satellites |
dBm |
-130 |
M.2.5.1 Minimum Requirements (moving scenario and periodic location)
The position estimates shall meet the accuracy requirement of table M.2-13 with the periodic location reporting interval defined in table M.2-13 after the first reported position estimates.
NOTE: In the actual testing the MS may report error messages until it has been able to acquire GPS 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 M.2-13.
Table M.2-13: Minimum requirements
|
Success Rate |
2-D position error |
Periodic location reporting interval |
|---|---|---|
|
95 % |
100 m |
2 s |