WCDMA Measurements: UE and NodeB RF Testing

This page describes WCDMA measurements as per 3GPP TS 34.121 from an RF and baseband domain perspective for both UE and NodeB. Circuit switched and Packet switched calls need to be tested from UE to NodeB and vice versa. This is referred to as a Mobile Originated call (MO call) and a Mobile Terminated call (MT call).

The establishment of the WCDMA call is carried out by connecting the UE with an R&S CMW500 system simulator or an Agilent 8960 system.

The call establishment confirms basic voice and data testing.

To perform RF and baseband testing, 3GPP TS 34.121(FDD) and TS 34.122(TDD) UE specifications need to be followed.

Conformance testing for NodeB is specified in 3GPP TS 25.141(FDD) and 3GPP TS 25.142(TDD).

WCDMA UE Transmitter Measurements

1. Nominal Maximum Output Power: This is examined for different bands and power classes to ensure it’s within tolerance.

2. Frequency Error: The frequency offset between the received RF modulated carrier frequency from NodeB and the one transmitted by the UE after necessary frequency correction is incorporated as commanded by NodeB.

   • The frequency error should not exceed +/- (0.1 ppm + 10 Hz).

3. EVM (Error Vector Magnitude): Another time-domain measure of the performance of the WCDMA transmitter.

   EVM gives an estimate of the modulation quality of the designed transmitter with the ideal WCDMA UE transmitter. To measure EVM, the vector difference between the reference signal and the signal under test is calculated.

• Measured EVM should be less than or equal to about 17.5%.

4. Peak Code Domain Error (PCDE): Another measure of transmitter distortion.

   It is defined using the mean value of the error vector power spread over code domain power. For the UE to be tested, the WCDMA system simulator should generate two coded channels with a spreading factor of 4 and DPCCH.

   The PCDE should be 15dB below the transmit signal power.

5. Adjacent Channel Leakage Ratio (ACLR): It measures how much adjacent power leaks from the wanted band to the adjacent band. As per specifications, there are two ACLR levels defined: one at 5MHz (about 33dB) and another at 10MHz (about 43 dB).

6. Spectrum Emission Mask: This is a measure of the transmitter’s RF power amplitude limits in addition to ACLR.

   The measurement is based on 30KHz and 1MHz bandwidths. The standard defines UE power density levels at these frequencies.

WCDMA Node B Transmitter Specifications

• Transmit Power: It is about 10-40 W in range and varies from manufacturer to manufacturer. Power control is up to 18 dB and in steps of either 1dB or 0.5dB.
• EVM: It is the same for NodeB as specified for UE.
• PCDE: It should be 33dB below the transmitted signal power for NodeB.
• ACLR: It is the same measure as specified in the UE part. The levels are different. ACLR performance levels are 45dB at 5MHz offset and 50dB at 10 MHz offset.
• Spectrum Emission Mask: The mask varies based on the power amplitude from the transmitter. The masks are defined in the standard and vary from 31 dBm to greater than 43 dBm. The measurements are based on 30KHz and 1MHz bandwidths.
• Spurious Emissions: Any unwanted frequencies at the output of the transmitter are referred to as spurious frequencies. The power emission limit for spurious is specified in the conformance requirement. For example, for 1920-1980 MHz (UTRA Rx Band I) the level is -96dBm with 100KHz measurement BW.

Receiver Specifications for UE/NodeB

The receiver sensitivity, BER, receiver adjacent channel selectivity, dynamic range, receiver blocking specifications (inband/out-of-band), and intermodulation requirements are the measurements carried out for both the WCDMA UE as well as NodeB testing.

Other than the normal Transmitter and Receiver measurements, radio characteristics viz. frame error rate, Signal to Interference ratio, and Interference power are measured by the physical layer and reported to upper layers and to NodeB via messages.

These measurements will help make decisions in handover from one cell to the other. It also helps in selecting the right cell during the initial network entry procedure.