4 General test conditions and declarations

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

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

The requirements of this clause apply to all tests in the present document, when applicable.

The general conditions during the tests should be according to the relevant parts of ETR 027 (methods of measurement for mobile radio equipment) with the exceptions and additions defined in the individual tests.

Many of the tests in the present document measure a parameter relative to a value which is not fully specified in the GSM specifications. For these tests, the conformance requirement is determined relative to a nominal value specified by the manufacturer.

Certain functions of a BTS are optional in the GSM specifications.

When specified in a test, the manufacturer shall declare the nominal value of a parameter, or whether an option is supported.

4.1 Output power and determination of power class

The manufacturer shall declare the rated maximum power per TRX for each supported modulation. For a micro or pico‑BTS, this shall be specified at the antenna connector. For a normal BTS, it shall be stated whether this is specified at the input to the combiner or at the antenna connector of the BSS.

For BTS belonging to a multicarrier BTS class, the manufacturer shall declare the maximum output power per carrier in case that all carriers are operated at the same nominal output power. The declaration shall be given for each modulation and for each supported number of carriers up to the maximum number on each antenna port. Additionally, the maximum total power supported shall be declared. The manufacturer shall also declare whether the BTS meets the requirements of a Wide Area, Medium Range and/or Local Area multicarrier BTS. The BTS may only be declared to meet the requirements of a Medium Range and/or Local Area multicarrier BTS class if the declared total power fulfils the power limit defined in table 4.1-2.

For a micro-BTS, the class of the micro‑BTS shall be determined from the declared maximum power, according to table 4.1-1. Where applicable, the manufacturer shall declare whether the BTS meets the requirements of a micro or pico-BTS.

For a BTS supporting other modulations as well (8-PSK, 16-QAM, 32-QAM, QPSK, AQPSK) or higher symbol rate the manufacturer shall declare the maximum output power capability for GMSK and each other supported combination of modulation and symbol rate. The TRX power class, the class of a micro-BTS or a pico-BTS is defined by the highest output power capability for any modulation.

For a BTS supporting AQPSK modulation, the manufacturer shall declare the smallest and largest supported absolute SCPIR_DL value (in dB). Transmitter measurements with AQPSK shall be based on these values.

Table 4.1-1: Micro and pico‑BTS Power Classes

TRX power class	GSM 900, ER-GSM 900, GSM 850, MXM 850 and GSM 700 micro and pico‑BTS Maximum output power	DCS 1800, PCS 1900 and MXM 1900 micro and pico‑BTS Maximum output power
M1	(>19)‑24 dBm	(>27)‑32 dBm
M2	(>14)‑19 dBm	(>22)‑27 dBm
M3	(>9)‑14 dBm	(>17)‑22 dBm
P1	(>13)‑20 dBm	(>16)‑23 dBm

Table 4.1-2: Multicarrier BTS classes

Multicarrier BTS class	Total power limit
Wide Area	No limit
Medium Range	≤ 38 dBm
Local Area	≤ 24 dBm

NOTE: For a normal BTS, the TRX power class can be determined from the manufacturers declared output power per TRX measured at the input to the combiner, according to the tables of TRX power classes in 3GPP TS 45.005. The test requirements for a normal BTS do not vary in this [TS] with TRX power classes. The definition of TRX power class only relates to the declared power per TRX and does not impose any requirement on the measured output power of the BTS.

4.2 Specified frequency range

The manufacturer shall declare:

– which of the frequency bands defined in subclause 3.3.1 are supported by the BSS; a BSS may support DCS 1800, GSM 450, GSM 480, PCS 1900, MXM 1900, GSM 850, MXM 850, GSM 700, T-GSM 810, ER-GSM 900 and one of the GSM 900 bands, but shall not be defined as supporting more than one out of the GSM 900 and the ER-GSM 900 bands;

– the frequency range within the above frequency band(s) supported by the BSS; This frequency range comprises the transmit and receive operating bands.

– in case of multicarrier BTS, the maximum Base Station RF bandwidth per transmit and receive antenna connector supported by the BSS.

– in case of multicarrier BTS, the maximum Transmit Filter bandwidth supported by the BSS.

Many tests in the present document are performed with appropriate frequencies in the bottom, middle and top of the operating frequency band of the BTS. These are denoted as RF channels B (bottom), M (middle) and T (top).

When a test is performed by a test laboratory, the ARFCNs to be used for RF channels B, M and T shall be specified by the laboratory. The laboratory may consult with operators, the manufacturer or other bodies.

When a test is performed by a manufacturer, the ARFCNs to be used for RF channels B, M and T may be specified by an operator.

4.3 Frequency hopping

The Manufacturer shall declare whether the BSS supports Slow Frequency Hopping (SFH) and if yes, which basic implementation or implementations is supported. If SFH is supported the BSS shall be able to switch to any frequency in its operating band on a time slot per time slot basis. For multicarrier BTSs in the BSS, it is sufficient to be able to switch to any frequency within the maximum Base Station RF bandwidth on a time slot per time slot basis.

Two basic implementations of SFH are possible:

a) baseband frequency hopping: frequency hopping is done by multiplexing the data of the logical channels to different TRXs according to the hopping scheme. The TRXs are fixed tuned to a dedicated ARFCN;

b) synthesizer frequency hopping: frequency hopping is done by tuning the TRX on a timeslot per timeslot basis. The logical channels are dedicated to a hopping TRX.

The detailed description of the frequency hopping scheme is described in 3GPP TS 45.002.

NOTE 1: For TU50 (ideal FH), sufficient decorrelation may be achieved with 4 frequencies spaced over 5 MHz.

NOTE 2: For TU 6 (ideal FH), TU3.6 (ideal FH), TU3 (ideal FH), TU1.5 (ideal FH) and TU1.2 (ideal FH), sufficient decorrelation cannot readily be achieved between the channel propagation conditions for each frequency hopped on. The requirements in 3GPP TS 45.005 for performance with TU1.2, TU1.5, TU3, TU3.6 or TU6(ideal FH) propagation condition cannot hence be tested and are thus absent in this test specification. They are inherently tested by TU50 (ideal SFH) together with TU3 (no SFH), TU3.6 (no SFH), TU 6 (no SFH), TU1.5 (no SFH) or TU1.2 (no SFH).

4.4 RF power control

RF power control functions ("dynamic power control") may optionally be implemented in GSM Base Station Systems according to 3GPP TS 45.008 as an operator choice. If implemented, the BSS shall be able to hop between any defined power level on a time slot per time slot basis. The manufacturer shall declare how many static power steps and how many dynamic steps are supported by the BSS. The number of static power steps and the total number of power control steps may be different for GMSK and other modulations (8-PSK, 16-QAM, 32-QAM, QPSK, AQPSK).

4.5 Downlink discontinuous transmission (DTX)

Downlink discontinuous transmission (DTX), as defined in the GSM 06‑series of specifications for full‑rate speech channels and in 3GPP TS 24.022 [30] and 3GPP TS 48.020 [31] for non‑transparent data, may optionally be implemented in the downlink BSS (transmitter) as an operator choice. All requirements in the present document, unless otherwise stated, apply whether downlink DTX is used or not.

4.6 Test environments

For each test in the present document, the environmental conditions under which the BSS is to be tested are defined:

4.6.1 Normal test environment

When a normal test environment is specified for a test, the test should be performed under any combination of conditions between the minimum and maximum limits stated in table 4.6-1.

Table 4.6-1: Limits of conditions for Normal Test Environment

Condition	Minimum	Maximum
Barometric pressure	86 kPa	106 kPa
Temperature	15C	30C
Relative Humidity	20 %	85 %
Power supply	Nominal, as declared by the manufacturer
Vibration	Negligible

The ranges of barometric pressure, temperature and humidity represent the maximum variation expected in the uncontrolled environment of a test laboratory. If it is not possible to maintain these parameters within the specified limits, the actual values shall be recorded in the test report.

NOTE: This may, for instance, be the case for measurements of radiated emissions performed on an open field test site.

4.6.2 Extreme test environment

The manufacturer shall declare one of the following:

a) the equipment class for the equipment under test, as defined in EN 300 019‑1‑3 , (Equipment Engineering (EE) [26]; Environmental conditions and environmental test for telecommunications equipment, Part 1‑3: Classification of environmental conditions, Stationary use at weather protected locations);

b) the equipment class for the equipment under test, as defined in EN 300 019‑1‑4 , (Equipment Engineering (EE) [27]; Environmental conditions and environmental test for telecommunications equipment, Part 1‑4: Classification of environmental conditions, Stationary use at non‑weather protected locations);

c) for equipment that does not comply to an EN 300 019‑1 class [11], the relevant classes from IEC 60 721 [13] documentation for Temperature, Humidity and Vibration shall be declared, as defined in IEC 60 721-3-3 "Stationary use at weather protected locations" [28] or IEC 60 721-3-4 "Stationary use at non weather protected locations" [29] respectively.

NOTE: Reduced functionality for conditions that fall out side of the standard operational conditions are not tested in the present document. These may be stated and tested separately.

4.6.2.1 Extreme temperature

When an extreme temperature test environment is specified for a test, the test shall be performed at the standard minimum and maximum operating temperatures defined by the manufacturer’s declaration for the equipment under test.

Minimum temperature:

– The test shall be performed with the environmental test equipment and methods of inducing the required environmental phenomena into the equipment, conforming to the test procedure of IEC 60068‑2‑1, Environmental Testing, Part 2: Tests ‑ Tests A: Cold [12]. The equipment shall be maintained at the stabilized condition for the duration of the test sequence.

Maximum temperature:

– The test shall be performed with the environmental test equipment and methods of inducing the required environmental phenomena in to the equipment, conforming to the test procedure of IEC 60068‑2‑2 (Environmental Testing, Part 2: Tests ‑ Tests Bd Dry heat) [12]. The equipment shall be maintained at the stabilized condition for the duration of the test sequence.

NOTE: It is recommended that the equipment is made fully operational prior to the equipment being taken to its lower operating temperature.

4.6.3 Vibration

When vibration conditions are specified for a test, the test shall be performed while the equipment is subjected to a vibration sequence as defined by the manufacturers declaration for the equipment under test. This shall use the environmental test equipment and methods of inducing the required environmental phenomena in to the equipment, conforming to the test procedure of IEC 60068‑2‑6, Environmental Testing, Part 2: Tests ‑ Test Fc and guidance [12]: Vibration (Sinusoidal) or IEC 60068‑2‑64, Test Fh: Vibration broad-band random (digital control) and guidance. Other environmental conditions shall be within the ranges specified in subclause 4.6.1, Normal test environment.

NOTE: The higher levels of vibration may induce undue physical stress in to equipment after a prolonged series of tests. The testing body should only vibrate the equipment during the RF measurement process.

4.6.4 Power supply

When extreme power supply conditions are specified for a test, the test shall be performed at the standard upper and lower limits of operating voltage defined by the manufacturer’s declaration for the equipment under test.

Upper voltage limit

The equipment shall be supplied with a voltage equal to the upper limit declared by the manufacturer (as measured at the input terminals to the equipment). The tests shall be carried out at the steady state minimum and maximum temperature limits declared by the manufacturer for the equipment, to the methods described in IEC 60 68‑2‑1 Test Ab/Ad: Cold and IEC 60068‑2‑2 Test Bb/Bd: Dry Heat [12].

Lower voltage limit

The equipment shall be supplied with a voltage equal to the lower limit declared by the manufacturer (as measured at the input terminals to the equipment). The tests shall be carried out at the steady state minimum and maximum temperature limits declared by the manufacturer for the equipment, to the methods described in IEC 60068‑2‑1 [12] Test Ab/Ad: Cold and IEC 60 068‑2‑2 Test Bb/Bd: Dry Heat [12].

4.7 Acceptable uncertainty of measurement equipment

The maximum acceptable uncertainty of measurement equipment is specified separately for each test, where appropriate. The measurement equipment shall enable the stimulus signals in the test case to be adjusted to within the specified tolerance, and the conformance requirement to be measured with an uncertainty not exceeding the specified values. All tolerances and uncertainties are absolute values, unless otherwise stated.

For the test methods, according to the present document, the measurement uncertainty figures shall be calculated in accordance with ETR 028 and shall correspond to an expansion factor (coverage factor) k = 1,96 or k = 2 (which provide confidence levels of respectively 95% and 95,45% in the case where the distributions characterising the actual measurement uncertainties are normal (Gaussian).

Subclause 4.6, Test environments:

Pressure ±5 kPa
Temperature ±2 degrees
Relative Humidity ±5 %
DC Voltage ±1,0 %
AC Voltage ±1,5 %
Vibration 10 %
Vibration frequency 0,1 Hz
The above values shall apply unless the test environment is controlled and the specification for the control of the test environment specifies the uncertainty for the parameter.

Transmitter

Subclause 6.2, Modulation accuracy:

Conformance requirement:

Frequency, GMSK ±10 Hz
± 5 Hz for GSM 400

Phase 1,5 degree rms

5 degrees peak

EVM -(0,75 + 0,025RMS_EVM) – +(0,75 + 0,025RMV_EVM) % RMS

± 4 % for individual measurement samples

Origin Offset suppression ± 1,5 dB

Frequency , 8-PSK ± 16 Hz

16-QAM ± 6 Hz

32-QAM ± 6 Hz

QPSK ± 6 Hz

AQPSK ± 6 Hz

NOTE 1: The value of the RMS EVM specification is a function of the value of RMS_EVM being measured. The asymmetric specification results from the RMS EVM minimisation method used for parameter estimation (see 3GPP TS 45.005, Annex G). This method of measurement for RMS EVM always produces a result that is lower than the actual value of RMS EVM.

NOTE 2: The value for individual EVM samples assumes a Rayleigh distribution of measurement errors. It represents the maximum 95^th percentile value test equipment should return when measuring a signal without error.

Subclause 6.3, Mean transmitted RF carrier power and equivalent combined power:

Conformance requirement:

RF power, for static power step 0 ±1,0 dB

Equivalent combined power, for static power step 0 ±1,0 dB

Relative RF Power, for other power steps ±0,7 dB

Subclause 6.4, Transmitted RF carrier power versus time:

Conformance requirement

RF power (0 dB reference) ±1,0 dB

RF power relative to 0 dB reference ±10 dB

Subclause 6.5.1, Spectrum due to modulation and wideband noise:

Conformance requirement

RF power (absolute limit values) 1,0 dB

NOTE 1: This may require calibration of the power levels corresponding to the limit values.

Relative RF power:

Offset from carrier, MHz	Power difference, dB	Uncertainty of relative power, dB
f  0.1 MHz	All	0,5 dB
0.1 MHz  f 1.8 MHz	 50 dB	0,7 dB
0.1 MHz  f 1.8 MHz	 50 dB	1,5 dB
 1.8 MHz	All	2,0 dB

Subclause 6.5.2, Switching transients spectrum:

Conformance requirement:

RF power: 1,5 dB

Relative RF power:

Power difference  50 dB 0,7 dB

Power difference  50 dB 1,5 dB

Subclause 6.6.1, Conducted spurious emissions from the transmitter antenna connector, inside the BTS transmit band:

Conformance requirement:

RF power: 1,5 dB

Subclause 6.6.2, Conducted spurious emissions from the transmitter antenna connector, outside the BTS transmit band:

Conformance requirement:

Conformance requirement i) (in the receive band of the BSS):

RF power 3 dB

Conformance requirements ii), iii) and iv) (elsewhere):

RF power:

f  2 GHz 1,5 dB

2 GHz  f  4 GHz 2,0 dB

f  4 GHz 4,0 dB

Subclause 6.7, Intermodulation attenuation and

Subclause 6.8, Intra base station system intermodulation attenuation:

Test case:

Relative RF power (of injected signal); 1,5 dB

Conformance requirement (outside RX band):

RF power; absolute limit values 1,5 dB

RF power, relative measurements 2,0 dB

Conformance requirement (inside RX band):

RF power; absolute limit values +4 dB – 3 dB

NOTE 2: The positive limit for uncertainty is greater than the negative limit because the measurement result can be increased (but not decreased) due to intermodulation products within the measurement apparatus.

Receiver

Where a measurement uncertainty of +5 dB ‑0 dB is specified for an input signal, the measured value of the input signal should be increased by an amount equal to the uncertainty with which it can be measured. This will ensure that the true value of the input signal is not below the specified nominal.

Subclause 7.1, Static layer 1 receiver functions:

Test case

RF power, lower limit 5 – 0 dB

RF power, ‑40 dBm nominal 2,5 dB

RF power, ‑23 and ‑15 dBm nominal 1,5 dB

Subclause 7.2, Erroneous frame indication performance:

Test case:

RF Power 5 – 0 dB

Subclause 7.3, Static reference sensitivity level:

Test case:

RF power 1,0 dB

Relative RF power ( adjacent timeslots) 3,0 dB

Subclause 7.4, Multipath reference sensitivity level:

Test case:

RF power 1,5 dB

Relative RF power 3,0 dB

Subclause 7.5, Reference interference level:

Test case:

RF power 5 – 0 dB

Relative RF power 1,0 dB

NOTE 3: The measurement uncertainty for a faded (multipath) input signal may depend on the time taken to average the power of the b signal from the fader. It may be possible to reduce the measurement time by measuring the power with the fader set to the same class of fade profile, but with an increased fade rate.

Subclause 7.6, Blocking characteristics:

Test case:

RF power, wanted signal 1,0 dB

RF power, interfering signal;

f  2 GHz 0,7 dB

2 GHz  f  4 GHz 1,5 dB

f  4 GHz 3,0 dB

Subclause 7.7, Intermodulation characteristics and subclause 7.8 AM suppression:

Test case:

RF power, wanted signal 1,0 dB

RF power, interfering signals 0,7 dB

Subclause 7.9, Spurious emissions from the receiver antenna connector:

Conformance requirement:

RF power;

f  2 GHz 1,5 dB

2 GHz  f  4 GHz 2,0 dB

f  4 GHz 4,0 dB

Clause 8, Radiated spurious emissions:

Conformance requirement:

RF power; 6,0 dB

Clause 9, Radio link management:

Test case:

RF power 1,0 dB

Relative RF power 0,7 dB

Conformance requirement:

Timing difference single measurement ±1/4 bit

average of 100 measurements ±0,1 bit

4.8 Interpretation of measurement results

The measurement value related to the corresponding limit shall be used to decide whether an equipment meets a requirement in the present document.

The measurement uncertainty for the measurement of each parameter shall be included in the test report.

The recorded value for the measurement uncertainty shall be, for each measurement, equal to or lower than the appropriate figure in subclause 4.7 of the present document.

NOTE: This procedure is recommended in ETR 028.

If the measurement apparatus for a test is known to have a measurement uncertainty greater than that specified in subclause 4.7, it is still permitted to use this apparatus provided that an adjustment is made to the measured value as follows.

The adjustment is made by subtracting the modulus of the specified measurement uncertainty in subclause 4.7 from the measurement uncertainty of the apparatus. The measured value is then increased or decreased by the result of the subtraction, whichever is most unfavourable in relation to the limit.

4.9 Selection of configurations for testing

Most tests in the present document are only performed for a subset of the possible combinations of test conditions. For instance:

‑ not all TRXs in the configuration may be specified to be tested;

‑ only one RF channel may be specified to be tested;

‑ only one timeslot may be specified to be tested.

When a test is performed by a test laboratory, the choice of which combinations are to be tested shall be specified by the laboratory. The laboratory may consult with operators, the manufacturer or other bodies.

When a test is performed by a manufacturer, the choice of which combinations are to be tested may be specified by an operator.

4.10 BTS Configurations

The present document has been written to specify tests for the standard configurations of BTS which have been assumed in GSM requirements specifications, In particular GSM 05.01, 05.02 and 05.05. However, there are other configurations of BTS which comply with these specifications, but for which the application of these specifications is not fully defined. For some such configurations there may be alternate ways to apply the requirements of this specification to testing of the configuration, or some variation in the test method may be necessary. It may therefore be necessary for the parties to the testing to reach agreement over the method of testing in advance.

If the BSS is supplied in a number of different environmental enclosures or configurations, it may not be necessary to test RF parameters for each environmental configuration, provided that it can be demonstrated that the equipment has been tested at the worst internal environmental conditions

If a BTS is supplied with a number of different configurations of passive TX antenna combiners, there may be alternate ways to demonstrate the compliance rather than performing the measurements for each configuration. As an example, the worst case configuration of the antenna combiners for a given test shall as a minimum be used for this purpose.

Where alternative interpretations of this specification are possible for a BSS configuration under test, the interpretation which has been adopted in performing the test shall be recorded with the test results.

Where variation in the test method within the present document has been necessary to enable a BSS configuration to be tested, the variation in the test method which has been made in performing the test shall be recorded with the test results. Where possible, agreement should be reached in advance about the nature of such a variation with any party who will later receive the test results.

Possible interpretations of the present document for some common configurations are given in the following subclauses.

4.10.1 Receiver diversity

i) For the tests in clause 7 of the present document, the specified test signals may be applied to one receiver antenna connector, with the remaining receiver antenna connectors being terminated with 50 ohms.

ii) For the tests in clause 7 of the present document, the specified test signals may be simultaneously applied to each of the receiver antenna connectors.

4.10.2 Duplexers

The requirements of the present document shall be met with a duplexer fitted, if a duplexer is supplied as part of the BSS. If the duplexer is supplied as an option by the manufacturer, sufficient tests should be repeated with and without the duplexer fitted to verify that the BSS meets the requirements of the present document in both cases.

The following tests should be performed with the duplexer fitted, and without it fitted if this is an option.

1) Subclause 6.3, Mean transmitted RF power, for the highest static power step only, if this is measured at the antenna connector.

2) Subclause 6.6.2, Conducted spurious emissions from the transmitter antenna connector; outside the BTS transmit band.

3) Subclause 6.8, Intra base station system intermodulation attenuation.

4) Subclause 7.4, Multipath reference sensitivity.

The remaining tests may be performed with or without the duplexer fitted.

NOTE 1: When performing receiver tests with a duplexer fitted, it is important to ensure that the output from the transmitters does not affect the test apparatus. This can be achieved using a combination of attenuators, isolators and filters.

NOTE 2: When duplexers are used, intermodulation products will be generated, not only in the duplexer but also in the antenna system. The intermodulation products generated in the antenna system are not controlled by ETSI specifications, and may degrade during operation (e.g. due to moisture ingress). Therefore, to ensure continued satisfactory operation of a BSS, an operator will normally select ARFCNs to minimize intermodulation products falling on receive channels. For testing of conformance requirements, an operator may specify the ARFCNs to be used.

4.10.3 Power supply options

If the BSS is supplied with a number of different power supply configurations, it may not be necessary to test RF parameters for each of the power supply options, provided that it can be demonstrated that the range of conditions over which the equipment is tested is at least as great as the range of conditions due to any of the power supply configurations.

This applies particularly if a BSS contains a DC rail which can be supplied either externally or from an internal mains power supply. In this case, the conditions of extreme power supply for the mains power supply options can be tested by testing only the external DC supply option. The range of DC input voltages for the test should be sufficient to verify the performance with any of the power supplies, over its range of operating conditions within the BTS, including variation of mains input voltage, temperature and output current.

4.10.4 Ancillary RF amplifiers

Ancillary RF amplifier: a piece of equipment, which when connected by RF coaxial cables to the BTS, has the primary function to provide amplification between the transmit and/or receive antenna connector of a BTS and an antenna without requiring any control signal to fulfil its amplifying function.

The requirements of the present document shall be met with the ancillary RF amplifier fitted. At tests according to clauses 6 and 7 for TX and RX respectively, the ancillary amplifier is connected to the BTS by a connecting network (including any cable(s), attenuator(s), etc.) with applicable loss to make sure the appropriate operating conditions of the ancillary amplifier and the BTS. The applicable connecting network loss range is declared by the manufacturer. Other characteristics and the temperature dependence of the attenuation of the connecting network are neglected. The actual attenuation value of the connecting network is chosen for each test as one of the applicable extreme values. The lowest value is used unless otherwise stated.

Sufficient tests should be repeated with the ancillary amplifier fitted and, if it is optional, without the ancillary RF amplifier to verify that the BSS meets the requirements of the present document in both cases.

For receiver tests only testing on TCH/FS is required

In test according to subclause 7.3 and 6.3 highest applicable attenuation value is applied.

4.10.5 BSS using antenna arrays

A BSS may be configured with a multiple antenna port connection for some or all of its TRXs or with an antenna array related to one cell (not one array per TRX). This section applies to a BSS which meets at least one of the following conditions:

– the transmitter output signals from one or more TRX appear at more than one antenna port; or

– there is more than one receiver antenna port for a TRX or per cell and an input signal is required at more than one port for the correct operation of the receiver (NOTE: diversity reception does not meet this requirement) thus the outputs from the transmitters as well as the inputs to the receivers are directly connected to several antennas (known as „air combining"); or

– transmitters and receivers are connected via duplexers to more than one antenna.

If a BSS is used, in normal operation, in conjunction with an antenna system which contains filters or active elements which are necessary to meet the GSM requirements, the tests of conformance requirements may be performed on a system comprising the BSS together with these elements, supplied separately for the purposes of testing. In this case, it must be demonstrated that the performance of the configuration under test is representative of the system in normal operation, and the conformance assessment is only applicable when the BSS is used with the antenna system.

For testing of conformance requirements of such a BSS, the following procedure may be used.

Receiver tests

For each test, the test signals applied to the receiver antenna connectors shall be such that the sum of the powers of the signals applied equals the power of the test signal(s) specified in the test.

An example of a suitable test configuration is shown in figure 4.10-1.

Figure 4.10-1: Receiver test setup

For spurious emissions from the receiver antenna connector, the test may be performed separately for each receiver antenna connector.

Transmitter tests

For each test, the minimum requirement shall be met by the sum of the signals emitted by each transmitter antenna connector. This may be assessed by separately measuring the signals emitted by each antenna connector and summing the results, or by combining the signals and performing a single measurement. The characteristics (e.g. amplitude and phase) of the combining network should be such that the power of the combined signal is maximised.

An example of a suitable test configuration is shown in figure 4.10-2.

Figure 4.10-2: Transmitter test setup

For Intermodulation attenuation, the test may be performed separately for each transmitter antenna connector.

4.10.6 BTS supporting 8-PSK modulation

If a TRX supports 8-PSK it shall, unless otherwise stated in the tests in clause 6 to 9, be tested at both GMSK and 8‑PSK modulation unless it can be demonstrated that it is sufficient to test only at GMSK or 8-PSK modulation.

If a BTS is configured with both TRXs supporting 8-PSK and TRXs not supporting 8-PSK, the stated number of TRXs to be tested shall apply to each type of TRX.

4.10.7 BTS supporting additional modulations in EGPRS2

If a TRX supports additional modulations (QPSK, 16-QAM or 32-QAM) it shall, unless otherwise stated in the tests in clause 6 to 9, be tested at GMSK as well as at the additional supported modulation unless it can be demonstrated that it is sufficient to test only at GMSK or the specific additional modulation.

If a BTS is configured with TRXs supporting additional modulations as well as TRXs not supporting additional modulations, the different types of TRX shall be counted separately, and the stated number of TRXs to be tested shall refer to each type of TRX separately.

4.10.8 Supported Symbol Rate

The tests in this specification are applicable to both normal symbol rate and higher symbol rate configurations, unless otherwise stated.

4.10.9 Support of RTTI and/or FANR

All tests are performed for BTTI configuration and without PAN, unless otherwise stated. Additional tests marked as specifically RTTI requirements without and with PAN, as well as BTTI with PAN shall be performed if BTS is declared to support these features.

4.10.10 Multicarrier BTS

If the BTS belongs to a multicarrier BTS class the configuration and number of TRXs to be used in the test corresponds to the configuration and number of active carriers at each transmitting antenna connector (i.e. at each transmitter output of a multicarrier transmitter or transceiver). The tests shall be repeated for each transmitting antenna connector, if connected to a multicarrier transmitter. If the maximum Base Station RF bandwidth is less than the relevant transmit band, and the transmitter is capable of operating on all parts of the relevant transmit band or a declared part of it (operating TX band according to subclause 4.2) by tuning, the transmitter tests are repeated until the whole relevant transmit band or the declared operating band is tested.

For multicarrier BTS testing, when the definition minimum carrier frequency spacing is used, the carrier spacing of 600 kHz shall apply for that test case.

The tests in this specification are based on the testing of multicarrier configurations for the supported numbers of carriers, operating at declared maximum power for each number of carriers equally distributed among the carriers. All supported numbers of carriers shall be included in the tests unless otherwise stated in the test case. Equipment that passes all the tests in this specification shall also comply in other configurations, with unequal distribution of power among the carriers, as long as these configurations are defined within the limits of total power, power control margin and maximum number of carriers in the multicarrier transmitter. To verify this compliance a test case with unequal power distribution shall be executed when stated in the subclause for the respective test:

– If support of four or more active carriers is declared: two carriers are configured to 2 dB higher power and two to 4 dB lower power than the declared maximum power at equal distribution. Any additional carrier shall be configured to the declared maximum power at equal distribution. If one carrier needs to be defined as BCCH carrier according to test case, the carrier with highest power shall be used for BCCH.

– If support of less than four active carriers is declared: One carrier is configured to 2 dB higher power and one to 4 dB lower power than the declared maximum power at equal distribution. Any additional carrier shall be configured to the declared maximum power at equal distribution. If one carrier needs to be defined as BCCH carrier according to test case, the carriers with highest power shall be used for BCCH.

If the BTS belongs to a multicarrier BTS class the manufacturer shall declare whether the BTS meets the requirements of the Wide Area class, the Medium Range class and/or the Local Area class. In addition, the manufacturer shall declare the supported combinations of number of carriers, output powers and the maximum Base Station RF bandwidth applicable for each connector. When the carriers in a transmitter test are required to be distributed over the maximum Base Station RF bandwidth, the supported maximum bandwidth at respective transmit antenna connector shall be applied.

The manufacturer shall also declare if the multicarrier BTS is equipped with multicarrier receiver and if any multicarrier receiver paths are equivalent, in terms of radio performance. The Medium Range and Local Area classes may not be declared without multicarrier receiver. The tests shall be repeated for each antenna connector, if connected to a multicarrier receiver. If the manufacturer has declared multicarrier receiver paths to be equivalent, it is sufficient to apply the specified test signal(s) at any one of the equivalent receiver paths’ antenna connectors. If the maximum Base Station RF bandwidth is less than the relevant receive band, and the receiver is capable of operating on all parts of the relevant receive band or a declared part of it (operating RX band according to subclause 4.2) by tuning, the receiver tests are repeated until the whole relevant receive band or the declared operating band is tested.

For any test that applies to a multicarrier BTS with multicarrier receiver, the required receiver resources for the declared maximum supported number of wanted signals shall be allocated and activated simultaneously at frequencies as evenly distributed as possible over the declared maximum Base Station RF bandwidth including the band edges of the Base Station RF bandwidth during the complete test, unless otherwise stated. The actual number and allocation of the applied input signals shall be as defined in each respective test. In case the supported maximum number of signals is higher than the number of applied wanted signals the remaining resources are allocated and activated for frequencies, not under test.

The declared configuration and stated performance shall be tested and fulfilled for any channel using the resource allocation and input signal configuration stated above. When the receiver resources in a test are required to be distributed over the maximum Base Station RF bandwidth, the maximum number of supported wanted signals shall be distributed over the supported maximum bandwidth at respective receive antenna connector.

For any test that applies to a multicarrier configuration in case of a multicarrier BTS all carriers shall apply the GMSK modulation, unless otherwise stated.

In test cases regarding unwanted emissions inband, i.e. including spectrum due to modulation and wideband noise, spurious emissions and intermodulation attenuation, detector mode RMS shall be used for conformance testing.

The vendor shall declare if the multicarrier BTS supports non-contiguous frequency allocation, defined as an allocation where two sub-blocks are separated by at least 5 MHz.

4.10.11 Support of EC-GSM-IoT

A BTS supporting EC-GSM-IoT shall, in addition to fulfilling EGPRS requirements, unless otherwise stated, fulfil the requirements for EC-channels in at least coverage classes CC1 and CC4 (no Overlaid CDMA applied). The BTS shall support 1 TS EC-RACH in CC1 and at least one of 1 TS EC-RACH and 2 TS EC-RACH in Coverage Classes higher than CC1. If the BTS supports CC5 then it shall support 2 TS EC-RACH using ESAB or EDAB (see 3GPP TS 45.002). Unless otherwise stated, the BTS requirements for EC-GSM-IoT are defined with RX diversity with two antennas with uncorrelated fast fading on fading channels and with equal gain between the two receive branches in case of sensitivity performance and interference level performance. For the performance with Overlaid CDMA the requirements are defined for single RX antenna configuration. The other receiver performance requirements for EC-GSM-IoT are defined for single RX antenna configuration.

The support of EC operation and the set of coverage classes supported, which of the 1 TS / 2 TS EC-RACH formats the BTS supports for Coverage Classes higher than CC1, whether the BTS supports Overlaid CDMA, and in this case the number of subchannels supported, shall be included in the manufacturer’s declaration. The BTS shall be equipped with RX diversity and shall support at least MCS-1 and MCS-1/16 for EC-PDTCH.

If supported, EC-PDTCH channels in CC1 using MCS-2 to MCS-4 and EC-PDTCH channels in CC1 using MCS-6 to MCS-9 need not be tested if corresponding channels for EGPRS with the same MCSs have been tested. Otherwise, for these EC-channels the same antenna configuration applies as for EGPRS, i.e. single RX antenna connector and no RX diversity.

In case an EC-channel in higher Coverage Class than 1 is used (i.e. CC2, CC3, CC4 or CC5), the BTS shall be able to distinguish between signals from up to 4 different assigned MSs on the same timeslot in case Overlaid CDMA (see 3GPP TS 45.002 and 3GPP TS 45.004) is supported.

Performance for Overlaid CDMA is defined for two SCPIR_UL configurations (see 3GPP TS 45.005):

– 0 dB, i.e. all Overlaid CDMA subchannels are received with the same power.

– 9 dB in case of two users per timeslot, or 3/ 6/ 9 dB in case of four users per timeslot.

To verify performance, tests are performed for both SCPIR_UL configurations for the supported number of subchannels. In case the manufacturer declares support for multiplexing of three users per timeslot the test for two users per timeslot applies. The requirements for the receiver performance for packet data and control channels in table 7.4-2b apply to Overlaid CDMA subchannel 1 when in specified and supported coverage class and the other subchannel(s) always is/are in CC2.

4.10.12 Support of Multilateration

A BTS supporting the Multilateration Timing Advance or Multilateration Observed Time Difference (see 3GPP TS 44.059 [34]) procedures may support timing advance estimation with increased accuracy which it reports to the BSC as BTS Reception Accuracy Capability (see 3GPP TS 49.031 [35]).

The tests for assessing the BTS Reception Accuracy Capability shall be carried out

– at the reference sensitivity level for PRACH/11bits (see 3GPP TS 45.005 [22]) if the BTS supports PEO operation, and

– at the input signal level for reference performance for EC-RACH (CC1) (see 3GPP TS 45.005 [22]) if the BTS supports EC-GSM-IoT.

The BTS Reception Accuracy Capability shall be tested using a minimum of 200 RACH bursts, subject to TU1.2 propagation conditions, wherein each RACH burst shall be sent with a random timing advance value in the range from 0 to 63 symbols with a granularity of 1/64 of a symbol (i.e. for the RACH 200 test signals each with a timing advance value randomly selected from the set {1/64, 2/64. ….. 63*64/64}. A BTS is said to have the BTS Reception Accuray Capability of 1/32, 1/16, 1/8, ¼, ½, or 1 normal symbol period if at most 10% of the estimated timing advance values (see 3GPP TS 45.010 [37] and 3GPP TS 49.031[35]) generated for a set of 200 RACH bursts have an error (absolute value of the difference of the test signal and the estimated timing advance value) exceeding the corresponding threshold value defined in table 4.10-1.

Table 4.10-1: Mapping of BTS Reception Capability vs timing advance error range

BTS Reception Accuracy Capability	Estimated timing advance threshold value
1/32	error ≤1/32
1/16	error ≤1/16
1/8	error ≤1/8
1/4	error ≤1/4
1/2	error ≤1/2
1	error ≤1