6.3 Frequency stability
25.1423GPPBase Station (BS) conformance testing (TDD)Release 17TS
6.3.1 Definition and applicability
Frequency stability is the ability of the BS to transmit at the assigned carrier frequency.
6.3.2 Minimum Requirements
The modulated carrier frequency of the BS is observed over a period of one timeslot. The frequency error shall be within the accuracy range given in Table 6.1B.
Table 6.1B: Frequency error Minimum Requirements
|
BS class |
Accuracy |
|
Wide Area BS |
±0,05 ppm |
|
Local Area BS |
±0,1 ppm |
|
Home BS |
±0,25 ppm |
The normative reference for this requirement is TS 25.105 [1] subclause 6.3.1.1 for the 3,84 Mcps TDD option, subclause 6.3.1.2 for the 1,28 Mcps TDD option and subclause 6.3.1.3 for the 7,68 Mcps TDD option.
TS 25.105 subclause 6.3 specifies the additional requirement that the BS shall use the same frequency source for both RF generation and the chip clock. Compliance with this requirement is demonstrated by manufacturer’s declaration; see subclause 5.4; a dedicated conformance test for this requirement is not defined.
6.3.3 Test purpose
The test purpose is to verify the accuracy of the carrier frequency across the frequency range and under normal and extreme conditions.
6.3.4 Method of test
6.3.4.1 Initial conditions
6.3.4.1.0 General test conditions
Test environment: normal; see subclause 5.9.1.
RF channels to be tested for single carrier: B, M and T; see subclause 5.3.
RF bandwidth positions to be tested for multicarrier: BRFBW, MRFBW and TRFBW in sinlge-band operation, see subclause 5.3; BRFBW_T’RFBW and B’RFBW_TRFBW in multi-band operation, see subclause 5.3.
The following additional test shall be performed:
On each RF channels or RF bandwidth positions the test shall be performed under extreme power supply as defined in subclause 5.9.4.
NOTE: Tests under extreme power supply also test extreme temperature.
6.3.4.1.1 3,84 Mcps TDD option
(1) The transmitter under test and all other transmitters of the base station (if any) are switched on.
(2) The power of the transmitters not under test (if any) are controlled down.
(3) Connect the tester to the BS antenna connector.
(4) Set the parameters of the transmitted signal according to table 6.2. For MBSFN IMB operation the set of parameters for the transmitted signals is according to IMB test model 1 in subclause 6.1.1.1.
Table 6.2: Parameters of the transmitted signal for frequency stability test
|
Parameter |
Value/description |
|
TDD Duty Cycle |
TS i; i = 0, 1, 2, …, 14: transmit, if i is even; receive, if i is odd. |
|
Time slot carrying SCH |
TS0 |
|
Time slots under test |
TS i, i even and non zero |
|
Number of DPCH in each time slot under test |
1 |
|
BS output power setting |
PRAT |
|
Data content of DPCH |
real life (sufficient irregular) |
6.3.4.1.2 1,28 Mcps TDD option
(1) Connect the tester to the BS antenna connector under test.
(2) For a BS declared to be capable of single carrier operation only, set the parameters of the transmitted signal according to table 6.2A at manufacturer’s declared output power, PRAT.
For a BS declared to be capable of multi-carrier operation, set the BS to transmit according to Table 6.2A on all carriers configured using the applicable test configuration and corresponding power setting specified in sub-clause 5.20 and 5.21
Table 6.2A: Parameters of the transmitted signal for Frequency stability test for 1,28 Mcps TDD
|
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 eachtime slot under test |
1 |
|
Data content of DPCH |
real life (sufficient irregular) |
6.3.4.1.3 7,68 Mcps TDD option
(1) The transmitter under test and all other transmitters of the base station (if any) are switched on.
(2) The power of the transmitters not under test (if any) are controlled down.
(3) Connect the tester to the BS antenna connector.
(4) Set the parameters of the transmitted signal according to table 6.2AA.
Table 6.2AA: Parameters of the transmitted signal for frequency stability test
|
Parameter |
Value/description |
|
TDD Duty Cycle |
TS i; i = 0, 1, 2, …, 14: transmit, if i is even; receive, if i is odd. |
|
Time slot carrying SCH |
TS0 |
|
Time slots under test |
TS i, i even and non zero |
|
Number of DPCH in each time slot under test |
1 |
|
BS output power setting |
PRAT |
|
Data content of DPCH |
real life (sufficient irregular) |
6.3.4.2 Procedure
(1) Measure the frequency error delta f across one burst (time slot), by applying the global in-channel Tx test method described in Annex C.
(2) Repeat step (1) for 200 bursts (time slots).
(3) Run steps (1) and (2) for RF channels or RF bandwidth positions defined in sbclasue 6.2.4.1.0.
In addition, for a multi-band capable BS, the following steps shall apply:
(4) For multi-band capable BS and single band tests, repeat the test per involved band with no carrier activated in the other band.
(5) For multi-band capable BS with separate antenna connector, the antenna connector not being under test in case of single-band or multi-band test shall be terminated.
6.3.5 Test Requirements
NOTE: If the Test Requirement below differs from the Minimum Requirement, then the Test Tolerance applied for this test is non-zero. The Test Tolerance for this test is defined in subclause 5.11 and the explanation of how the Minimum Requirement has been relaxed by the Test Tolerance is given in Annex D.
For all measured bursts (time slots), the frequency error of each carrier, derived according to subclause 6.3.4.2, shall be within the accuracy range given in table 6.2B.
Table 6.2B: Frequency error Test Requirements
|
BS class |
Accuracy |
|
Wide Area BS |
± (0,05 ppm + 12 Hz) |
|
Local Area BS |
± (0,1 ppm + 12 Hz) |
|
Home BS |
± (0,25 ppm + 12 Hz) |