7.3 Physical channels
38.2113GPPNRPhysical channels and modulationRelease 17TS
7.3.1 Physical downlink shared channel
7.3.1.1 Scrambling
Up to two codewords 
can be transmitted. In case of single-codeword transmission, 
.
For each codeword 
, the UE shall assume the block of bits , where is the number of bits in codeword 
transmitted on the physical channel, are scrambled prior to modulation, resulting in a block of scrambled bits according to
where the scrambling sequence is given by clause 5.2.1. The scrambling sequence generator shall be initialized with
where
– 
equals the higher-layer parameter dataScramblingIdentityPDSCH if configured and the RNTI equals the C-RNTI, MCS-C-RNTI, or CS-RNTI, and the transmission is not scheduled using DCI format 1_0 in a common search space;
– equals the higher-layer parameter dataScramblingIdentityPDSCH if configured in a common MBS frequency resource and the RNTI equals the G-RNTI, G-CS-RNTI, or MCCH-RNTI, and the transmission is scheduled using DCI in a common search space configured in the common MBS frequency resource;
– equals
– the higher-layer parameter dataScramblingIdentityPDSCH if the codeword is scheduled using a CORESET with CORESETPoolIndex equal to 0;
– the higher-layer parameter dataScramblingIdentityPDSCH2 if the codeword is scheduled using a CORESET with CORESETPoolIndex equal to 1;
if the higher-layer parameters dataScramblingIdentityPDSCH and dataScramblingIdentityPDSCH2 are configured together with the higher-layer parameter CORESETPoolIndex containing two different values, and the RNTI equals the C-RNTI, MCS-C-RNTI, or CS-RNTI, and the transmission is not scheduled using DCI format 1_0 in a common search space;
– otherwise
and where corresponds to the RNTI associated with the PDSCH transmission as described in clause 5.1 of [6, TS 38.214].
7.3.1.2 Modulation
For each codeword , the UE shall assume the block of scrambled bits are modulated as described in clause 5.1 using one of the modulation schemes in Table 7.3.1.2-1, resulting in a block of complex-valued modulation symbols .
Table 7.3.1.2-1: Supported modulation schemes.
|
Modulation scheme |
Modulation order |
|
QPSK |
2 |
|
16QAM |
4 |
|
64QAM |
6 |
|
256QAM |
8 |
|
1024QAM |
10 |
7.3.1.3 Layer mapping
The UE shall assume that complex-valued modulation symbols for each of the codewords to be transmitted are mapped onto one or several layers according to Table 7.3.1.3-1. Complex-valued modulation symbols for codeword shall be mapped onto the layers , where is the number of layers and is the number of modulation symbols per layer.
Table 7.3.1.3-1: Codeword-to-layer mapping for spatial multiplexing.
|
Number of layers |
Number of codewords |
Codeword-to-layer mapping
|
|
|
1 |
1 |
|
|
|
2 |
1 |
|
|
|
3 |
1 |
|
|
|
4 |
1 |
|
|
|
5 |
2 |
|
|
|
|
|||
|
6 |
2 |
|
|
|
|
|||
|
7 |
2 |
|
|
|
|
|||
|
8 |
2 |
|
|
|
|
|||
7.3.1.4 Antenna port mapping
The block of vectors , shall be mapped to antenna ports according to
where , . The set of antenna ports 
shall be determined according to the procedure in [4, TS 38.212].
7.3.1.5 Mapping to virtual resource blocks
The UE shall, for each of the antenna ports used for transmission of the physical channel, assume the block of complex-valued symbols conform to the downlink power allocation specified in [6, TS 38.214] and are mapped in sequence starting with to resource elements in the virtual resource blocks assigned for transmission which meet all of the following criteria:
– they are in the virtual resource blocks assigned for transmission;
– the corresponding physical resource blocks are declared as available for PDSCH according to clause 5.1.4 of [6, TS 38.214];
– the corresponding resource elements in the corresponding physical resource blocks are
– not used for transmission of the associated DM-RS or DM-RS intended for other co-scheduled UEs as described in clause 7.4.1.1.2;
– not used for non-zero-power CSI-RS, which is according to clause 7.4.1.5 and not configured by TRS-ResourceSet IE, if the corresponding physical resource blocks are for a PDSCH scheduled by a PDCCH with the CRC scrambled by C-RNTI, MCS-C-RNTI, CS-RNTI, G-RNTI for multicast, G-CS-RNTI, or a PDSCH with SPS, except if the non-zero-power CSI-RS is a CSI-RS configured by the higher-layer parameter CSI-RS-Resource-Mobility in the MeasObjectNR IE or except if the non-zero-power CSI-RS is an aperiodic non-zero-power CSI-RS resource;
– not used for PT-RS according to clause 7.4.1.2;
– not declared as ‘not available for PDSCH according to clause 5.1.4 of [6, TS 38.214].
The mapping to resource elements allocated for PDSCH according to [6, TS 38.214] and not reserved for other purposes shall be in increasing order of first the index over the assigned virtual resource blocks, where is the first subcarrier in the lowest-numbered virtual resource block assigned for transmission, and then the index .
7.3.1.6 Mapping from virtual to physical resource blocks
The UE shall assume the virtual resource blocks are mapped to physical resource blocks according to the indicated mapping scheme, non-interleaved or interleaved mapping. If no mapping scheme is indicated, the UE shall assume non-interleaved mapping.
For non-interleaved VRB-to-PRB mapping, virtual resource block is mapped to physical resource block , except for PDSCH transmissions scheduled with DCI format 1_0 in a common search space in which case virtual resource block is mapped to physical resource block where is the lowest-numbered physical resource block in the control resource set where the corresponding DCI was received. When two PDCCH candidates from two linked common search space sets as indicated by the higher-layer parameter searchSpaceLinking are detected, and the two linked common search space sets are associated with different control resource sets, the control resource set with the lowest number among the two linked control resource sets is used to determine .
For interleaved VRB-to-PRB mapping, the mapping process is defined by:
– Resource block bundles are defined as
– for PDSCH transmissions scheduled with DCI format 1_0 with the CRC scrambled by SI-RNTI in Type0-PDCCH common search space in CORESET 0, the set of resource blocks in CORESET 0 are divided into resource-block bundles in increasing order of the resource-block number and bundle number where is the bundle size and is the size of CORESET 0.
– resource block bundle consists of resource blocks if and resource blocks otherwise,
– all other resource block bundles consists of resource blocks.
– for PDSCH transmissions scheduled with DCI format 1_0 in any common search space in bandwidth part with starting position , other than Type0-PDCCH common search space in CORESET 0, the set of virtual resource blocks , where is the size of CORESET 0 if CORESET 0 is configured for the cell and the size of initial downlink bandwidth part if CORESET 0 is not configured for the cell, are divided into virtual resource-block bundles in increasing order of the virtual resource-block number and virtual bundle number and the set of physical resource blocks are divided into physical resource-block bundles in increasing order of the physical resource-block number and physical bundle number, where , is the bundle size, and is the lowest-numbered physical resource block in the control resource set where the corresponding DCI was received. When two PDCCH candidates from two linked search space sets as indicated by the higher-layer parameter searchSpaceLinking are detected, and the two linked search space sets are associated with different control resource sets, the control resource set with the lowest number among the two linked control resource sets is used to determine .
– resource block bundle 0 consists of resource blocks,
– resource block bundle consists of resource blocks if and resource blocks otherwise,
– all other resource block bundles consists of resource blocks.
– for all other PDSCH transmissions, the set of resource blocks in bandwidth part 
with starting position are divided into resource-block bundles in increasing order of the resource-block number and bundle number where 
is the bundle size for bandwidth part 
provided by the higher-layer parameter vrb-ToPRB-Interleaver for DCI formats 1_0 and 1_1 in a UE-specific search space, or vrb-ToPRB-InterleaverDCI-1-2 for DCI format 1_2, and
– resource block bundle 0 consists of resource blocks,
– resource block bundle consists of resource blocks if and resource blocks otherwise,
– all other resource block bundles consists of resource blocks.
– Virtual resource blocks in the interval are mapped to physical resource blocks according to
– virtual resource block bundle is mapped to physical resource block bundle
– virtual resource block bundle 
is mapped to physical resource block bundle 
where
– The UE is not expected to be configured with simultaneously with a PRG size of 4 as defined in [6, TS 38.214]
The UE may assume that the same precoding in the frequency domain is used within a PRB bundle and the bundle size is determined by clause 5.1.2.3 in [6, TS 38.214]. The UE shall not make any assumption that the same precoding is used for different bundles of common resource blocks.
For PDSCH transmissions scheduled by DCI format 4_1 or 4_2, and using G-RNTI or G-CS-RNTI, the quantities and in this clause are replaced by and , respectively, and is the bundle size for the common MBS frequency resource provided by the higher-layer parameter vrb-ToPRB-Interleaver in PDSCH-Config-Multicast.
For PDSCH transmissions scheduled by DCI format 4_0, and using G-RNTI or MCCH-RNTI, the quantities and in this clause are replaced by and , respectively, and .
7.3.2 Physical downlink control channel (PDCCH)
7.3.2.1 Control-channel element (CCE)
A physical downlink control channel consists of one or more control-channel elements (CCEs) as indicated in Table 7.3.2.1-1.
Table 7.3.2.1-1: Supported PDCCH aggregation levels.
|
Aggregation level |
Number of CCEs |
|
1 |
1 |
|
2 |
2 |
|
4 |
4 |
|
8 |
8 |
|
16 |
16 |
7.3.2.2 Control-resource set (CORESET)
A control-resource set consists of resource blocks in the frequency domain and symbols in the time domain.
A control-channel element consists of 6 resource-element groups (REGs) where a resource-element group equals one resource block during one OFDM symbol. Resource-element groups within a control-resource set are numbered in increasing order in a time-first manner, starting with 0 for the first OFDM symbol and the lowest-numbered resource block in the control resource set.
A UE can be configured with multiple control-resource sets. Each control-resource set is associated with one CCE-to-REG mapping only.
The CCE-to-REG mapping for a control-resource set can be interleaved or non-interleaved and is described by REG bundles:
– REG bundle 
is defined as REGs 
where is the REG bundle size, , and is the number of REGs in the CORESET
– CCE 
consists of REG bundles 
where 
is an interleaver
For non-interleaved CCE-to-REG mapping, and .
For interleaved CCE-to-REG mapping, for and for . The interleaver is defined by
where 
.
The UE is not expected to handle configurations resulting in the quantity not being an integer.
For a CORESET configured by the ControlResourceSet IE:
– is given by the higher-layer parameter frequencyDomainResources;
– is given by the higher-layer parameter duration, where is supported only if the higher-layer parameter dmrs-TypeA-Position equals 3;
– interleaved or non-interleaved mapping is given by the higher-layer parameter cce-REG-MappingType;
– equals 6 for non-interleaved mapping and is given by the higher-layer parameter reg-BundleSize for interleaved mapping;
– is given by the higher-layer parameter interleaverSize;
– is given by the higher-layer parameter shiftIndex if provided, otherwise ;
– for both interleaved and non-interleaved mapping, the UE may assume
– the same precoding being used within a REG bundle if the higher-layer parameter precoderGranularity equals sameAsREG-bundle;
– the same precoding being used across the all resource-element groups within the set of contiguous resource blocks in the CORESET, and that no resource elements in the CORESET overlap with an SSB or LTE cell-specific reference signals as indicated by the higher-layer parameter lte-CRS-ToMatchAround, lte-CRS-PatternList1, or lte-CRS-PatternList2, if the higher-layer parameter precoderGranularity equals allContiguousRBs.
For CORESET 0 configured by the ControlResourceSetZero IE:
– and are defined by clause 13 of [5, TS 38.213];
– the UE may assume interleaved mapping
– ;
– ;
–
– the UE may assume normal cyclic prefix when CORESET 0 is configured by MIB or SIB1;
– the UE may assume the same precoding being used within a REG bundle.
7.3.2.3 Scrambling
The UE shall assume the block of bits , where is the number of bits transmitted on the physical channel, is scrambled prior to modulation, resulting in a block of scrambled bits according to
where the scrambling sequence 
is given by clause 5.2.1. The scrambling sequence generator shall be initialized with
where
– for a UE-specific search space as defined in clause 10 of [5, TS 38.213], equals the higher-layer parameter pdcch-DMRS-ScramblingID if configured;
– for a PDCCH with the CRC scrambled by G-RNTI, G-CS-RNTI, or MCCH-RNTI in a common search space as defined in clause 10 of [5, TS 38.213], equals the higher-layer parameter pdcch-DMRS-ScramblingID if configured in a common MBS frequency resource;
– otherwise
and where
– is given by the C-RNTI for a PDCCH in a UE-specific search space if the higher-layer parameter pdcch-DMRS-ScramblingID is configured, and
– otherwise.
7.3.2.4 PDCCH modulation
The UE shall assume the block of bits to be QPSK modulated as described in clause 5.1.3, resulting in a block of complex-valued modulation symbols .
7.3.2.5 Mapping to physical resources
The UE shall assume the block of complex-valued symbols to be scaled by a factor 
and mapped to resource elements used for the monitored PDCCH and not used for the associated PDCCH DMRS in increasing order of first 
, then 
. The antenna port 
.
7.3.3 Physical broadcast channel
7.3.3.1 Scrambling
The UE shall assume the block of bits, where 
is the number of bits transmitted on the physical broadcast channel, are scrambled prior to modulation, resulting in a block of scrambled bits according to
where the scrambling sequence 
is given by clause 5.2. The scrambling sequence shall be initialized with at the start of each SS/PBCH block where
– for , is the two least significant bits of the candidate SS/PBCH block index
– for , is the three least significant bits of the candidate SS/PBCH block index
with being the maximum number of candidate SS/PBCH blocks in a half frame, as described in [5, TS 38.213].
7.3.3.2 Modulation
The UE shall assume the block of bits are QPSK modulated as described in clause 5.1.3, resulting in a block of complex-valued modulation symbols .
7.3.3.3 Mapping to physical resources
Mapping to physical resources is described in clause 7.4.3.