8.4 Performance requirements for PRACH
36.1413GPPBase Station (BS) conformance testingEvolved Universal Terrestrial Radio Access (E-UTRA)Release 17TS
8.4.1 PRACH false alarm probability and missed detection
8.4.1.1 Definition and applicability
The performance requirement of PRACH for preamble detection is determined by the two parameters: total probability of false detection of the preamble (Pfa) and the probability of detection of preamble (Pd). The performance is measured by the required SNR at probability of detection, Pd of 99%. Pfa shall be 0.1% or less.
Pfa is defined as a conditional total probability of erroneous detection of the preamble (i.e. erroneous detection from any detector) when input is only noise.
Pd is defined as conditional probability of detection of the preamble when the signal is present. The erroneous detection consists of several error cases – detecting different preamble than the one that was sent, not detecting a preamble at all or correct preamble detection but with the wrong timing estimation. For AWGN, a timing estimation error occurs if the estimation error of the timing of the strongest path is larger than 1.04us. For ETU70, and EPA1 a timing estimation error occurs if the estimation error of the timing of the strongest path is larger than 2.08us. The strongest path for the timing estimation error refers to the strongest path (i.e. average of the delay of all paths having the same highest gain = 310ns for ETU) in the power delay profile.
The test preambles for normal mode are listed in table A.6-1 and the test preambles for high speed mode restriced set type A are listed in A.6-2. The test preambles for coverage enhancement are listed in table A.6-3. The test preambles for high speed mode restriced set type B are listed in A.6-4.
The normal mode test (Table 8.4.1.5-1) is applicable to all BS. The high speed mode test restricted set type A (Table 8.4.1.5-2) and high speed mode restricted set type B (table 8.4.2.1-5) are applicable to high speed BS supporting high speed mode restricted set A and restricted set type B respectively. The coverage enhancement tests (Table 8.4.1.5-3 and Table 8.4.1.5-4) are applicable to the base stations supporting coverage enhancement.
8.4.1.2 Minimum Requirement
The minimum requirement is in TS 36.104 [2] subclause 8.4.1.1 and 8.4.2.1.
8.4.1.3 Test purpose
The test shall verify the receiver’s ability to detect PRACH preamble under multipath fading propagation conditions for a given SNR.
8.4.1.4 Method of test
8.4.1.4.1 Initial Conditions
Test environment: Normal, see subclause D.2.
RF channels to be tested: M; see subclause 4.7
1) Connect the BS tester generating the wanted signal, multipath fading simulators and AWGN generators to all BS antenna connectors for diversity reception via a combining network as shown in Annex I.3.1 or Annex I.3.2 as applicable.
8.4.1.4.2 Procedure
1) Adjust the AWGN generator, according to the channel bandwidth.
Table 8.4.1.4.2-1: AWGN power level at the BS input
|
Channel bandwidth [MHz] |
AWGN power level |
|
1.4 |
-89.7 dBm / 1.08MHz |
|
3 |
-85.7 dBm / 2.7MHz |
|
5 |
-83.5 dBm / 4.5MHz |
|
10 |
-80.5 dBm / 9MHz |
|
15 |
-78.7 dBm / 13.5MHz |
|
20 |
-77.4 dBm / 18MHz |
2) The characteristics of the wanted signal shall be configured according to the corresponding UL reference measurement channel defined in Annex A.
3) The multipath fading emulators shall be configured according to the corresponding channel model defined in Annex B.
4) Adjust the frequency offset of the test signal according to Table 8.4.1.5-1 or 8.4.1.5-2 or 8.4.1.5-3 or 8.4.1.5-4 or 8.4.1.5-5.
5) Adjust the equipment so that the SNR specified in Table 8.4.1.5-1 or 8.4.1.5-2 or 8.4.1.5-3 or 8.4.1.5-4 or 8.4.1.5-5 is achieved at the BS input during the PRACH preambles.
6) The test signal generator sends a preamble and the receiver tries to detect the preamble. This pattern is repeated as illustrated in figure 8.4.1.4.2-1. The preambles are sent with certain timing offsets as described below. The following statistics are kept: the number of preambles detected in the idle period and the number of missed preambles.
Figure 8.4.1.4.2-1: PRACH preamble test pattern
The timing offset base value is set to 50% of Ncs. This offset is increased within the loop, by adding in each step a value of 0.1us, until the end of the tested range, which is 0.9us. Then the loop is being reset and the timing offset is set again to 50% of Ncs. The timing offset scheme is presented in Figure 8.4.1.4.2-2.
Figure 8.4.1.4.2-2: Timing offset scheme
8.4.1.5 Test Requirement
Pfa shall not exceed 0.1%. Pd shall not be below 99% for the SNRs in Tables 8.4.1.5-1 to 8.4.1.5-5.
Table 8.4.1.5-1: PRACH missed detection test requirements for Normal Mode
|
Number of TX antennas |
Number of RX antennas |
Propagation conditions and correlation matrix (Annex B) |
Frequency offset |
SNR [dB] |
||||
|
Burst format 0 |
Burst format 1 |
Burst format 2 |
Burst format 3 |
Burst format 4 |
||||
|
1 |
2 |
AWGN |
0 |
-13.9 |
-13.9 |
-16.1 |
-16.2 |
-6.9 |
|
ETU 70 Low* |
270 Hz |
-7.4 |
-7.2 |
-9.4 |
-9.5 |
0.5 |
||
|
4 |
AWGN |
0 |
-16.6 |
-16.4 |
-18.7 |
-18.5 |
-9.5 |
|
|
ETU 70 Low* |
270 Hz |
-11.5 |
-11.1 |
-13.5 |
-13.3 |
-4.5 |
||
|
8 |
AWGN |
0 |
-19.5 |
-19.1 |
-21.2 |
-21 |
-11.5 |
|
|
ETU 70 Low* |
270 Hz |
-15.7 |
-15.3 |
-17.2 |
-16.9 |
-8.0 |
||
|
Note*: Not applicable for Local Area BS and Home BS. |
||||||||
The requirements in Table 8.4.1.5-2 shall not be applied to Local Area BS and Home BS
Table 8.4.1.5-2: PRACH missed detection test requirements for High speed Mode restricted set type A
|
Number of TX antennas |
Number of RX antennas |
Propagation conditions and correlation matrix (Annex B) |
Frequency offset |
SNR [dB] |
|||
|
Burst format 0 |
Burst format 1 |
Burst format 2 |
Burst format 3 |
||||
|
1 |
2 |
AWGN |
0 |
-13.8 |
-13.9 |
-16.0 |
-16.3 |
|
ETU 70 Low |
270 Hz |
-6.8 |
-6.7 |
-8.7 |
-8.9 |
||
|
AWGN |
625 Hz |
-12.1 |
-12.0 |
-14.1 |
-14.1 |
||
|
AWGN |
1340 Hz |
-13.1 |
-13.2 |
-15.2 |
-15.4 |
||
|
4 |
AWGN |
0 |
-16.6 |
-16.3 |
-18.6 |
-18.5 |
|
|
ETU 70 Low |
270 Hz |
-11.2 |
-10.8 |
-13.1 |
-13.1 |
||
|
AWGN |
625 Hz |
-14.6 |
-14.3 |
-16.5 |
-16.5 |
||
|
AWGN |
1340 Hz |
-15.6 |
-15.2 |
-17.5 |
-17.5 |
||
|
8 |
AWGN |
0 |
-19.0 |
-18.8 |
-20.6 |
-20.7 |
|
|
ETU 70 Low |
270 Hz |
-15.0 |
-14.5 |
-16.4 |
-16.4 |
||
|
AWGN |
625 Hz |
-17.4 |
-17.1 |
-19.0 |
-19.1 |
||
|
AWGN |
1340 Hz |
-18.4 |
-18.1 |
-20.2 |
-20.2 |
||
Table 8.4.1.5-3: PRACH missed detection requirements for coverage enhancement (PRACH frequency hopping OFF)
|
Number of TX antennas |
Number of RX antennas |
Propagation conditions and correlation matrix (Annex B) |
Frequency offset |
Number of Repetitions |
SNR [dB] |
|||
|
Burst format 0 |
Burst format 1 |
Burst format 2 |
Burst format 3 |
|||||
|
1 |
2 |
AWGN |
0 |
4 |
– |
– |
-21.0 |
-20.8 |
|
8 |
-21.4 |
-21.0 |
– |
– |
||||
|
16 |
– |
– |
-24.8 |
-24.7 |
||||
|
32 |
-25.3 |
-25.0 |
– |
– |
||||
|
EPA1 Low |
270 Hz |
4 |
– |
– |
-11.5 |
-11.1 |
||
|
8 |
-12.4 |
-11.7 |
– |
– |
||||
|
16 |
– |
– |
-16.6 |
-16.6 |
||||
|
32 |
-18.4 |
-18.0 |
– |
– |
||||
|
Note 1: Under fading channels, the PRACH detection performance may be significantly different with different PRACH Configuration Indexes. The requirements in this table are defined based on the simulation results with PRACH Configuration Indexes (3, 19, 35, 51) for Format 0, Format 1, Format 2, and Format 3 respectively. |
||||||||
Table 8.4.1.5-4: PRACH missed detection requirements for coverage enhancement (PRACH frequency hopping ON)
|
Number of TX antennas |
Number of RX antennas |
Propagation conditions and correlation matrix (Annex B) |
Frequency offset |
Number of Repetitions |
SNR [dB] |
|||
|
Burst format 0 |
Burst format 1 |
Burst format 2 |
Burst format 3 |
|||||
|
1 |
2 |
EPA1 Low |
270 Hz |
4 |
– |
– |
-14.9 |
-14.7 |
|
8 |
-15.6 |
-15.2 |
– |
– |
||||
|
16 |
– |
– |
-19.5 |
-19.6 |
||||
|
32 |
-20.7 |
-20.5 |
– |
– |
||||
|
Note 1: Under fading channels, the PRACH detection performance may be significantly different with different PRACH Configuration Indexes. The requirements in this table are defined based on the simulation results with PRACH Configuration Indexes (3, 19, 35, 51) for Format 0, Format 1, Format 2, and Format 3 respectively. Note 2: The requirements in this table are defined under the assumption that UE RF tuning during PRACH frequency hopping has no impact on the symbols in PRACH subframes and thus all symbols in PRACH subframes are available for the transmission of PRACH preambles. Note 3: The requirements in this table are defined under the assumption that the PRACH frequency offset (prach-FreqOffset-r13) is 0 and frequency hopping offset is Note 4: The requirements in this table apply for channel bandwidth of 5MHz, 10MHz, 15MHz or 20MHz. For channel bandwidth of 3MHz, the requirements in Table 8.4.1.5-3 apply. |
||||||||
-6, where Table 8.4.2.1-5 PRACH missed detection requirements for High speed Mode restricted set type B
|
Number of TX antennas |
Number of RX antennas |
Propagation conditions and correlation matrix (Annex B) |
Frequency offset |
SNR [dB] |
|||
|
Burst format 0 |
Burst format 1 |
Burst format 2 |
Burst format 3 |
||||
|
1 |
2 |
AWGN |
0 |
-14.2 |
-13.8 |
-16.4 |
-16.5 |
|
AWGN |
625 Hz |
-11.7 |
-11.4 |
-13.6 |
-13.6 |
||
|
ETU 70 Low |
270 Hz |
-6.7 |
-6.3 |
-8.5 |
-8.6 |
||
|
AWGN |
1875 Hz |
-11.5 |
-11.1 |
-13.5 |
-13.7 |
||
|
AWGN |
1944 Hz |
-11.4 |
-11.1 |
-13.5 |
-13.7 |
||
|
4 |
AWGN |
0 |
-16.8 |
-16.3 |
-18.8 |
-18.8 |
|
|
AWGN |
625 Hz |
-14.1 |
-13.8 |
-15.8 |
-15.9 |
||
|
ETU 70 Low |
270 Hz |
-11.2 |
-10.7 |
-12.9 |
-12.8 |
||
|
AWGN |
1875 Hz |
-13.9 |
-13.5 |
-15.6 |
-16.0 |
||
|
AWGN |
1944 Hz |
-13.9 |
-13.5 |
-15.6 |
-16.0 |
||
|
8 |
AWGN |
0 |
-19.3 |
-18.8 |
-20.9 |
-20.9 |
|
|
AWGN |
625 Hz |
-16.1 |
-16.0 |
-17.8 |
-17.9 |
||
|
ETU 70 Low |
270 Hz |
-14.7 |
-14.5 |
-16.5 |
-16.9 |
||
|
AWGN |
1875 Hz |
-16.0 |
-15.7 |
-17.7 |
-18.1 |
||
|
AWGN |
1944 Hz |
-16.0 |
-15.7 |
-17.7 |
-18.1 |
||
NOTE: If the above Test Requirement differs from the Minimum Requirement then the Test Tolerance applied for this test is non-zero. The Test Tolerance for this test and the explanation of how the Minimum Requirement has been relaxed by the Test Tolerance is given in Annex G.