7.4.3 SS/PBCH block
38.2113GPPNRPhysical channels and modulationRelease 17TS
7.4.3.1 Time-frequency structure of an SS/PBCH block
In the time domain, an SS/PBCH block consists of 4 OFDM symbols, numbered in increasing order from 0 to 3 within the SS/PBCH block, where PSS, SSS, and PBCH with associated DM-RS are mapped to symbols as given by Table 7.4.3.1-1.
In the frequency domain, an SS/PBCH block consists of 240 contiguous subcarriers with the subcarriers numbered in increasing order from 0 to 239 within the SS/PBCH block. The quantities 
and 
represent the frequency and time indices, respectively, within one SS/PBCH block. The UE may assume that the complex-valued symbols corresponding to resource elements denoted as ‘Set to 0’ in Table 7.4.3.1-1 are set to zero. The quantity 
in Table 7.4.3.1-1 is given by . The quantity 
is the subcarrier offset from subcarrier 0 in common resource block to subcarrier 0 of the SS/PBCH block, where is obtained from the higher-layer parameter offsetToPointA.
– For operation with shared spectrum channel access in FR2-2 and for operation without shared spectrum channel access, the 4 least significant bits of 
are given by the higher-layer parameter ssb-SubcarrierOffset and for FR1 the most significant bit of 
is given by in the PBCH payload as defined in clause 7.1.1 of [4, TS 38.212].
– For operation with shared spectrum channel access in FR1, the 4 least significant bits of are given by the higher-layer parameter ssb-SubcarrierOffset and the most significant bit of is given by in the PBCH payload as defined in clause 7.1.1 of [4, TS 38.212]. If , ; otherwise, .
If ssb-SubcarrierOffset is not provided, is derived from the frequency difference between the SS/PBCH block and Point A.
The UE may assume that the complex-valued symbols corresponding to resource elements that are part of a common resource block partially or fully overlapping with an SS/PBCH block and not used for SS/PBCH transmission are set to zero in the OFDM symbols partially or fully overlapping with OFDM symbols where SS/PBCH is transmitted.
For an SS/PBCH block, the UE shall assume
– antenna port is used for transmission of PSS, SSS, PBCH and DM-RS for PBCH,
– the same cyclic prefix length and subcarrier spacing for the PSS, SSS, PBCH and DM-RS for PBCH,
– for SS/PBCH block type A, 
and 
with the quantities 
, and expressed in terms of 15 kHz subcarrier spacing, and
– for SS/PBCH block type B in FR2-1, 
and 
with the quantity 
expressed in terms of the subcarrier spacing provided by the higher-layer parameter subCarrierSpacingCommon and expressed in terms of 60 kHz subcarrier spacing;
– for SS/PBCH block type B in FR2-2, and with the quantity expressed in terms of the SS/PBCH block subcarrier spacing and expressed in terms of 60 kHz subcarrier spacing;
– the centre of subcarrier 0 of resource block coincides with the centre of subcarrier 0 of a common resource block with the subcarrier spacing
– provided by the higher-layer parameter subCarrierSpacingCommon for operation without shared spectrum channel access in FR1 and FR2-1; and
– same as the subcarrier spacing of the SS/PBCH block for operation without shared spectrum access in FR2-2 and for operation with shared spectrum channel access.
– This common resource block overlaps with subcarrier 0 of the first resource block of the SS/PBCH block.
The UE may assume that SS/PBCH blocks transmitted with the same block index on the same center frequency location are quasi co-located with respect to Doppler spread, Doppler shift, average gain, average delay, delay spread, and, when applicable, spatial Rx parameters. The UE shall not assume quasi co-location for any other SS/PBCH block transmissions other than what is specified in [5, TS 38.213].
Table 7.4.3.1-1: Resources within an SS/PBCH block for PSS, SSS, PBCH, and DM-RS for PBCH.
|
Channel or signal |
OFDM symbol number |
Subcarrier number |
|
PSS |
0 |
56, 57, …, 182 |
|
SSS |
2 |
56, 57, …, 182 |
|
Set to 0 |
0 |
0, 1, …, 55, 183, 184, …, 239 |
|
2 |
48, 49, …, 55, 183, 184, …, 191 |
|
|
PBCH |
1, 3 |
0, 1, …, 239 |
|
2 |
0, 1, …, 47, |
|
|
DM-RS for PBCH |
1, 3 |
|
|
2 |
|
7.4.3.1.1 Mapping of PSS within an SS/PBCH block
The UE shall assume the sequence of symbols 
constituting the primary synchronization signal to be scaled by a factor 
to conform to the PSS power allocation specified in [5, TS 38.213] and mapped to resource elements in increasing order of 
where and 
are given by Table 7.4.3.1-1 and represent the frequency and time indices, respectively, within one SS/PBCH block.
7.4.3.1.2 Mapping of SSS within an SS/PBCH block
The UE shall assume the sequence of symbols 
constituting the secondary synchronization signal to be scaled by a factor 
and mapped to resource elements in increasing order of 
where and 
are given by Table 7.4.3.1-1 and represent the frequency and time indices, respectively, within one SS/PBCH block.
7.4.3.1.3 Mapping of PBCH and DM-RS within an SS/PBCH block
The UE shall assume the sequence of complex-valued symbols constituting the physical broadcast channel to be scaled by a factor 
to conform to the PBCH power allocation specified in [5, TS 38.213] and mapped in sequence starting with 
to resource elements which meet all the following criteria:
– they are not used for PBCH demodulation reference signals
The mapping to resource elements not reserved for PBCH DM-RS shall be in increasing order of first the index 
and then the index 
, where 
and 
represent the frequency and time indices, respectively, within one SS/PBCH block and are given by Table 7.4.3.1-1.
The UE shall assume the sequence of complex-valued symbols 
constituting the demodulation reference signals for the SS/PBCH block to be scaled by a factor of to conform to the PBCH power allocation specified in [5, TS 38.213] and to be mapped to resource elements in increasing order of first 
and then 
where 
and 
are given by Table 7.4.3.1-1 and represent the frequency and time indices, respectively, within one SS/PBCH block.
7.4.3.2 Time location of an SS/PBCH block
The locations in the time domain where a UE shall monitor for a possible SS/PBCH block are described in clause 4.1 of [5, TS 38.213].