6.3 Mean transmitted RF carrier power and equivalent combined power

3GPP51.021Base Station System (BSS) equipment specificationRadio aspectsRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

6.3.1 Test purpose

1) To verify the accuracy of the mean transmitted RF carrier power across the frequency range and at each power step.

2) If the BSS supports EC-GSM-IoT, to verify a sufficient phase and amplitude coherency, by measuring the equivalent combined power.

This test is also used to determine the parameter "power level", used in subclause 6.5.1.2.

6.3.2 Test case

For a normal BTS, the power shall be measured at the input of the TX combiner or at the BSS antenna connector. For a micro‑BTS, the power shall be measured at the BSS antenna connector. For a multicarrier BTS the power shall be measured at each transmitting BSS antenna connector. The Manufacturer shall declare the maximum output power of the BSS for each supported modulation at the same reference point as the measurement is made. The TX combiner shall have the maximum number of TRXs connected to it so that the measurement of the mean transmitted RF carrier power can be used as a reference for the measurement of transmitted carrier power versus time in subclause 6.4.

NOTE: The value of the output power measured at the antenna connector is generally more useful for cell planning, and may be required for regulatory purposes.

All TRXs in the configuration shall be switched on transmitting full power in all time slots for at least 1 hour before starting the test.

The Manufacturer shall declare how many TRXs the BSS supports:

1 TRX: The TRX shall be tested at B, M and T;

2 TRX: The TRXs shall each be tested at B, M and T;

3 TRX or more: Three TRXs shall each be tested at B, M and T.

In case of multicarrier BTS the tests shall be performed for the declared number(s) of carriers, operating at equally distributed power at minimum carrier frequency spacing and grouped at B, M and T, for each antenna connector.

In addition the test case with unequal power distribution according to subclause 4.10.10 shall be performed for the declared maximum number of carriers.

If the Manufacturer declares that Synthesizer Slow Frequency Hopping is supported by the BSS, the BSS shall be configured with the number of TRXs and frequency allocation defined above and SFH enabled.

Whether SFH is supported or not, the measurement shall be carried out on all of the 3 frequencies in turn. The measurement bandwidth shall be at least 300 kHz.

i) For a BTS not supporting EC-GSM-IoT:

The BSS under test shall be set to transmit at least 3 adjacent time slots in a TDMA frame at the same power level. The RMS power level shall be measured on a time slot basis over the useful part of one of the active time slots and then the average of the logarithmic value taken over at least 200 time slots. Only active bursts shall be included in the averaging process.

ii) For a BTS supporting EC-GSM-IoT:

For all GMSK tests at static RF power step 0 without dynamic Downlink Power Control:

The BSS under test shall be set to transmit on time slots TN4 to TN7 in a TDMA frame at static RF power step 0, and shall transmit with phase and amplitude coherency the same pseudo-random GMSK bit sequence and the same USF value per TDMA frame, using TSC 0 from TSC set 1. Further time slots may be active but shall not use TSC 0 from TSC set 1 and shall use GMSK at static RF power step 0 without dynamic Downlink Power Control. The RMS power level shall be measured on a time slot basis over the useful part of one of the active time slots and then the average of the logarithmic value taken over at least 200 time slots. Only active bursts shall be included in the averaging process. In addition, the equivalent combined power shall be measured by combining the signals in TN4 to TN7 in the same TDMA frame, averaging over at least 200 valid TDMA frames (excluding idle frames) and converting the average to logarithmic scale.

For all other mean transmitted RF carrier power tests:

The test conditions under i) apply.

For the definition of the useful part of the time slot see figure 6.4-1, and for further details see 3GPP TS 45.004 and 3GPP TS 45.010. For timing on a per time slot basis, in case of normal symbol rate, each time slot may contain 156.25 modulating symbols, or 2 time slots may contain 157 and 6 time slots 156 modulating symbols according to 3GPP TS 45.010. In case of higher symbol rate each time slot may contain 187,5 symbols or 188,4 symbols on timeslot 0 and 4 and 187,2 symbols on the remaining timeslots in a TDMA-frame according to 3GPP TS 45.010. If the BSS supports EC-GSM-IoT, only the implementation option with integral symbol periods in normal symbol period bursts is allowed according to 3GPP TS 45.010, for normal and higher symbol rate, respectively.

The mean transmitted RF carrier power shall be measured at each nominal power level as specified. As a minimum, one time slot shall be tested on each TRX. Any TRX which is a dedicated BCCH shall only be tested at highest static power step.

For BTS supporting operation in the ER-GSM 900 band, RF channels B, M, and T refer to the operating frequency band excluding the frequency range 918 to 921 MHz. In addition the test is required to be carried out in the frequency range 918 to 921 MHz for following RF channels: B’= 918.2 MHz, M’= 919.6 MHz and T’= 921.0 MHz to ensure that the maximum RF carrier power of the ER-GSM 900 BTS fulfils the requirements defined in 3GPP TS 45.005, clause 4.1.2.4.

6.3.3 Void

6.3.4 Conformance requirement

Test Environment

Normal: Each TRX specified in the test case shall be tested.

Extreme power supply: One TRX shall be tested, on one ARFCN, for highest static power step only.

NOTE: tests under extreme power supply are carried out at extreme temperature limits.

Minimum requirement

The BSS shall support Nmax steps of Static Power Control for each supported modulation with respect to the declared output power as declared by the manufacturer. For the modulation with the highest output power, Nmax shall be at least 6.

The static power step N has the range from the highest static power level to Nmax inclusive, where

– The Highest Static Power Level corresponds to the maximum single carrier output power declared by the manufacturer. For multicarrier BTS, the Highest Static Power Level corresponds to maximum output power per carrier for each supported number of carriers declared by the manufacturer.

– The Lowest Static Power Level is defined as the Highest Static Power Level reduced by Nmax power steps, where the number of power steps can be different for each supported modulation.

The output power measured when the TRX is set to Highest Static Power Control Level shall have a tolerance of 2 dB under normal conditions and 2,5 dB under extreme conditions, relative to the maximum power declared by the manufacturer for the modulation under test. In this test, this measured output power is termed the maximum BTS output power. Static power control shall allow the RF output power to be reduced from the maximum BTS output power for the modulation with the highest output power capability in at least 6 steps of nominally 2 dB with a tolerance of 1 dB for each modulation referenced to the previous level of the same modulation. In addition, the actual absolute output power for each supported modulation at each static RF power step (N) , with the exception below for the highest RF output power level for 8-PSK, QPSK, AQPSK, 16-QAM and 32-QAM, shall be 2*N dB below the maximum BTS output power for the modulation with the highest output power capability with a tolerance of 3 dB under normal conditions and 4 dB under extreme conditions.

In addition to the Static Power Control levels the BSS may utilize up to M steps of dynamic Downlink Power Control. M can have an upper limit of 0 to 15.

Dynamic Downlink power control shall allow the RF output power to be reduced in M steps with a step size of 2 dB with a tolerance of 1,5 dB referenced to the previous level.

Each dynamic Downlink Power Control level shall have a tolerance of 3 dB under normal conditions and 4 dB under extreme conditions relative to 2*Y dB below the maximum BTS output power for the modulation with the highest output power capability, where Y is the sum of the number of static and dynamic steps below Highest Static Power Control Level for the modulation with the highest output power capability.

For BTS supporting 8-PSK, QPSK, AQPSK, 16-QAM and/or 32-QAM the output power for GMSK, 8-PSK, QPSK, AQPSK, 16-QAM and 32-QAM shall be nominally the same for any supported static and dynamic power control level. An exception is allowed for the maximum output power of the respective modulation QPSK, AQPSK, 8-PSK, 16-QAM and 32-QAM, which may be lower than the GMSK output power for the same static or dynamic power control level. The nominal size of the first step down from the respective maximum power level of QPSK, 8-PSK, AQPSK, 16-QAM and 32-QAM may be in the range 0 to 2 dB. The output power of QPSK, 8-PSK, AQPSK, 16-QAM and 32-QAM for the respective second highest static or dynamic power control level shall be the same as the GMSK output power for the corresponding static or dynamic power control level within a tolerance of ±1 dB The number of static RF power steps and the total number of power control steps may be different for GMSK and other supported modulations (8-PSK, QPSK, AQPSK, 16-QAM and 32-QAM).

For BTS supporting operation in the ER-GSM 900 band, for the test in the frequency range 918 to 921 MHz, maximum allowed RF output power actually transmitted by the BTS depends on the coexistence scenarios and coordination between operators or defined by regulatory authority. The maximum allowed RF output power actually transmitted by the BTS is specified in TS 45.005, clause 4.1.2.4.

Table 6.3-1 specifies the maximum allowed RF output power levels for RF channels B’, M’ and T’ under test, at the BTS transmit antenna connector, for different coexistence scenarios and two configured MCL values (67 dB for the uncoordinated case and 74 dB for the coordinated case). All power level entries in Table 6.3-1 need to be tested and include all kind of output power tolerances.

Table 6.3-1: Maximum allowed RF output power levels for RF channels B’, M’ and T’ in the ER-GSM 900 extension band.

Scenario	MCL	B’	M’	T’
Coexistence with GSM Normal BTS / MCBTS in E-GSM band	67 dB	26.6 dBm	35 dBm	43.4 dBm
Coexistence with GSM Normal BTS / MCBTS in E-GSM band	74 dB	33.6 dBm	42 dBm	50.4 dBm
Coexistence with UTRA / E-UTRA BS in E-GSM band	67 dB	8.3 dBm	23.7 dBm	39.1 dBm
Coexistence with UTRA / E-UTRA BS in E-GSM band	74 dB	15.3 dBm	30.7 dBm	46.1 dBm

If the BSS supports EC-GSM-IoT, the measured equivalent combined power shall exceed the maximum GMSK output power declared by the manufacturer by at least 10 dB under normal conditions and 9.5 dB under extreme conditions.

6.3.5 Requirement reference

3GPP TS 45.005 subclause 4.1.2.