J.3 Physical signals, channels mapping and precoding
38.176-23GPPIntegrated Access and Backhaul (IAB) conformance testingNRPart 2: radiated conformance testingRelease 17TS
J.3.1 General
Unless otherwise stated, the transmission on antenna port(s) is defined by using a precoder matrix 
of size , where is the number of physical transmit antenna elements configured per test , is the number of ports for a reference signal or physical channel configured per test, and is the first port for that reference signal or physical channel as defined in clauses 7.3 and 7.4 in TS 38.211 [9]. This precoder takes as an input a block of signals for antenna port(s) , , 
, with 
being the number of modulation symbols per antenna port including the reference signal symbols, and generates a block of signals the elements of which are to be mapped onto the frequency-time index pair 
as per the test configuration but transmitted on different physical antenna elements:
For Clause 6 and 8, the transmission of PDCCH and PDCCH DMRS on antenna port is defined by using a precoder matrix 
of size 2×1. This precoder takes as an input a block of signals for antenna port(s) , and generates a block of signals the elements of which are to be mapped onto the frequency-time index pair 
as per the test configuration but transmitted on different physical antenna elements:
The precoder matrix 
is specific to the test case configuration 
is defined in Clause 5.2.2.2 of TS 38.214 [24].
The transmission on PT-RS antenna port is associated (using same precoder) with the lowest indexed DM-RS antenna port among the DM-RS antenna ports assigned for the PDSCH.
The physical antenna elements are identified by indices
, where 
is the number of physical antenna elements configured per test.
Modulation symbols with (i.e. PSS, SSS, PBCH and DM-RS for PBCH) are directly mapped to first physical antenna element.
Modulation symbols 
for CSI-RS resources which configured for tracking with one port are directly mapped to first physical antenna element.
Modulation symbols 
for CSI-RS resources which configured for beam refinement with one port are directly mapped to first physical antenna element.
Modulation symbols 
for NZP CSI-RS which configured for CSI acquisition with 
are mapped to the physical antenna index 
where 
is the number of NZP CSI-RS ports configured per test.
Annex K (informative):
Measuring noise close to noise-floor
As the emission level seen by the measurement receiver (PUEM) for co-location requirements are very low, it is suggested to measure relative noise change instead of absolute noise level. For the situation where the noise level is stable, the noise level change can be identified by a relative noise measurement method. This method measures the relative noise change extracted from when the test object is operating and when the power is disconnected. From the two measured noise levels the relative noise change can be determined. The relations between measured noise change 1, noise floor N0 and the relation to PUEM with respect to the noise floor denoted 2 is visualized in the left drawing in figure K-1.
Figure K-1: Relative noise measurement
The absolute emission level in decibel scale is determined from a relative measurement of 1 as:
where N0 is the noise floor of the measurement receiver and 2 is plotted as function of 1 at the right in figure K-1. The absolute noise floor of the measurement receiver, including probe antenna, cables, filter and LNA is determined by a calibration procedure. The calibration will determine the absolute emission level (N0) accuracy of measuring out-of-band unwanted emission close to the thermal noise floor.
Annex L (normative):
In-channel TX tests for IAB-DU
The Annex H in TS 38.141-2 [6] applies to FR1 and FR2 IAB-DU.
Annex M (normative): In-channel TX tests for IAB-MT