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TD-SCDMA UE RF Conformance testing and Measurements

This TD-SCDMA Test and measurement tutorial covers TD-SCDMA baseband and RF measurements useful for UE conformance testing. Following basic TD-SCDMA UE transmitter and Receiver tests are done during this TD-SCDMA UE testing.

Transmitter and receiver specifications vary for 3.68Mcps,1.28Mcps and 7.68Mcps TDD versions of TD-SCDMA. They all will have different channel spacings. 3.68Mcps has 5 MHz channel spacing,1.28Mcps has 1.6MHz and 7.68Mcps has 10MHz channel spacing.

TD-SCDMA UE Transmitter

Following TD-SCDMA measurements are carried on UE transmitter part as TD-SCDMA testing.

Maximum output power

This test ascertains that UE fulfills the requirements for Maximum Output Power as per power class.

For 1.28Mcps TDD option, UE maximum power output limits are specified below with tolerance including power class.

power class Output power(max.) nominal tolerance limit
1 +33dBm +1dB/-3dB
2 +24dBm +1dB/-3dB
3 +21dBm +2dB/-2dB

Minimum TX output power

The idea of this test is to verify whether UE works efficiently as lower power as specified. The requirements for Minimum Transmit Output Power is -49dBm (at mid, low and high channels). This limit is for 1.28Mcps TDD version. For 3.84Mcps it is specified as -44dBm and for 7.68Mcps it is -41dBm.

Open loop power control

The requirements for Open Loop Power Control for TD-SCDMA compliant UE is with tolerance of +/-9dB under normal conditions and +/-12dB under extreme conditions.

Output power dynamics

This test help to check whether UE fulfills requirements on power control step tolerance. For 1dB step it should be in between -0.5 and +0.5 dB. Different step size has different upper and lower limits.

UE frequency stability

The UE modulated carrier frequency shall be accurate to within +/-0.1 PPM observed over a period of one timeslot compared to carrier frequency received from the BS.

Spectrum Emission Mask (SEM)

This test helps in verifying that the UE fulfills requirements on Spectrum Emission Mask. Spectrum emission mask is to be measured at maximum output power under low, mid, and high channel conditions.

Spurious limit

The spurious and harmonics should be under control in order for UE to perform well in the system. For frequency band of 921MHz to 925MHz and with 100KHz of measurement bandwidth the minimum requirement of spurious is -60dBm. The other bands have got different limits. This is for 1.28Mcps TDD version.

Adjacent channel leakage power ratio (ACLR)

This test helps in verifying that the UE fulfills requirements for Adjacent Channel Leakage Ratio (ACLR). ACLR and channel power is to be measured at the maximum power level under low, mid, and high channel conditions.

Specification Max. relative as per R99 at normal VBAT Max. relative as oer HSUPA category7 at normal VBAT
ACLR +/- 1.6MHz -38dBc -35dBc
ACLR +/- 3.2MHz -50dBc -43dBc

Modulation accuracy

This test helps in verifying that the UE fulfills requirements on EVM (14%rms at -20 dBm Pout with Mid channel only and for 16QAM modulation), phase discontinuity and frequency error, PCDE(-21dB at High channel only) and IQ imbalance level.

TD-SCDMA UE Receiver

Following TD-SCDMA measurements are carried on UE receiver part as TD-SCDMA testing.

Receiver sensitivity level (RX EVM)

The EVM test with the lower power level is to verify that the UE fulfills requirements on receiver sensitivity.

EVM

EVM is measured in dB as shown in the equation, Where in Perror is the RMS power of the error vector and Pref is the reference constellation average power.

EVM of 14%rms with Mid channel at -20dBm Pout

RX RSSI verification

The purpose is to test the RSSI from the UE with TD-SCDMA mode of operation. The power sweep will test that all analogue gain settings are functional and the frequency sweep will test that frequency response is sufficiently flat.

Power Sweep

Specification Min. Max. Power in (dBm)
RSSI Accuracy -4 +4 -90 to -70

Frequency Sweep

Specification Min. Max. Power in (dBm)
RSSI Accuracy -4 +4 -70

TD-SCDMA RELATED LINKS

Difference between TD-SCDMA WCDMA CDMA2000
TD-SCDMA chipset vendors, TD-SCDMA Chip Vendors
TD-SCDMA UE conformance testing


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