6.3.1 Scrambling
36.2113GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical channels and modulationRelease 17TS
For each codeword 
, the block of bits 
, where 
is the number of bits in codeword 
transmitted on the physical channel in one subframe/slot/subslot, shall be scrambled prior to modulation, resulting in a block of scrambled bits 
according to
where the scrambling sequence 
is given by clause 7.2. The scrambling sequence generator shall be initialised at the start of each subframe, where the initialisation value of 
depends on the transport channel type according to
where 
corresponds to the RNTI associated with the PDSCH transmission as described in clause 7.1 TS 36.213 [4].
For BL/CE UEs, the same scrambling sequence is applied per subframe to PDSCH for a given block of 
subframes. The subframe number of the first subframe in each block of 
consecutive subframes, denoted as 
, satisfies 
. For the 
block of 
subframes, the scrambling sequence generator shall be initialised with
where
and 
is the absolute subframe number of the first downlink subframe intended for PDSCH. The PDSCH transmission spans 
consecutive subframes including subframes that are not BL/CE DL subframes where the PDSCH transmission is postponed.
For BL/CE UEs,
– if the PDSCH is carrying SIB1-BR
– 
– else if the PDSCH is carrying SI message (except for SIB1-BR) or if the PDSCH transmission is associated with P-RNTI or SC-RNTI:
– 
for frame structure type 1 and 
for frame structure type 2
– otherwise
– 
for UEs assuming CEModeA (according to the definition in Clause 12 of [4]) or configured with CEModeA
– 
for frame structure type 1 and 
for frame structure type 2 for UEs assuming CEModeB (according to the definition in Clause 12 of [4]) or configured with CEModeB
For PDSCH with a subframe duration, up to two codewords can be transmitted in one subframe, i.e., 
. In the case of single codeword transmission, 
is equal to zero.