10 Modulation accuracy
25.1533GPPRelease 17TSUTRA repeater conformance testing (LCR TDD)
10.1 Error Vector Magnitude
10.1.1 Definition and applicability
The modulation accuracy is defined by the Error Vector Magnitude (EVM), which is a measure of the difference between the theoretical waveform and a modified version of the measured waveform. This difference is called the error vector. The measured waveform is modified by first passing it through a matched root raised cosine filter with bandwidth 1.28MHz and roll-off =0.22. The waveform is then further modified by selecting the frequency, absolute phase, absolute amplitude and chip clock timing so as to minimise the error vector. The EVM result is defined as root of the ratio of the mean error vector power to the mean reference signal power expressed as a %.
The measurement interval is one power control group (timeslot). The repeater shall operate with an ideal LCR TDD signal in the pass band of the repeater at a level, which produce the maximum rated output power per channel, as specified by the manufacturer.
10.1.2 Minimum requirements
The Error Vector Magnitude shall not be worse than 8 %.
10.1.3 Test purpose
To verify that the EVM is within the limit specified in 10.1.2 after the signal passed through the Repeater..
10.1.4 Method of test
10.1.4.1 Initial conditions
1) Set-up the equipment as shown in annex A.
2) Connect the signal generator equipment to the Repeater input port.
3) Connect the signal analyser to the Repeater output port..
10.1.4.2 Procedure
1) Set the signal generator to transmit one signal according to table 10.1.
Table 10.1: Parameters of the transmitted signal for Error Vector Magnitude testing
|
Parameter |
Value/description |
|
TDD Duty Cycle |
TS i; i = 0, 1, 2, …, 6: Transmit, if i is 0,4,5,6; receive, if i is 1,2,3. |
|
Time slots under test |
TS4, TS5 and TS6 |
|
Number of DPCH in each time slot under test |
10 |
|
Power of each DPCH |
1/10 of Base Station output power |
|
Base station power |
PRAT |
2) Adjust the input power to the Repeater to create the maximum nominal Repeater output power at maximum gain.
3) Measure the Error Vector Magnitude for both paths uplink and downlink of the Repeater.
10.1.5 Test requirements
The error vector magnitude (EVM) measured according to subclause 10.1.4.2 shall not exceed 8 %.
10.2 Peak code domain error
10.2.1 Definition and applicability
The code domain error is computed by projecting the error vector power onto the code domain at a specific spreading factor. The error power for each code is defined as the ratio to the mean power of the reference waveform expressed in dB. And the Peak Code Domain Error is defined as the maximum value for Code Domain Error. The measurement interval is one timeslot.
10.2.2 Minimum requirement
The peak code domain error shall not exceed -30 dB at spreading factor 16.
10.2.3 Test purpose
To verify that the peak code domain error is within the limit specified in 10.2.2 after the signal passed through the Repeater.
10.2.4 Method of test
10.2.4.1 Initial conditions
1) Set-up the equipment as shown in annex A.
2) Connect the signal generator equipment to the Repeater input port.
3) Connect the signal analyser to the Repeater output port..
10.2.4.2 Procedure
1) Set the signal generator to transmit one signal according to table 10.2.
Table 10.2: Parameters of the transmitted signal for Peak Code Domain Error testing
|
Parameter |
Value/description |
|
TDD Duty Cycle |
TS i; i = 0, 1, 2, …, 6: transmit, if i is 0,4,5,6; receive, if i is 1,2,3. |
|
Time slots under test |
TS4, TS5 and TS6 |
|
BS output power setting |
PRAT |
|
Number of DPCH in each time slot under test |
10 |
|
Power of each DPCH |
1/10 of Base Station output power |
|
Data content of DPCH |
real life (sufficient irregular) |
|
Spreading factor |
16 |
2) Adjust the input power to the Repeater to create the maximum nominal Repeater output power at maximum gain.
3) Measure the Peak Code Domain Error for both paths uplink and downlink of the Repeater.
10.2.5 Test requirements
The peak code domain error measured according to subclause 10.2.4.2 shall not exceed -30 dB at spreading factor 16.