6.2.1 Transport block CRC attachment
38.2123GPPMultiplexing and channel codingNRRelease 17TS
Error detection is provided on each UL-SCH transport block through a Cyclic Redundancy Check (CRC).
The entire transport block is used to calculate the CRC parity bits. Denote the bits in a transport block delivered to layer 1 by
, and the parity bits by
, where 
is the payload size and 
is the number of parity bits. The lowest order information bit 
is mapped to the most significant bit of the transport block as defined in Clause 6.1.1 of [TS38.321].
The parity bits are computed and attached to the UL-SCH transport block according to Clause 5.1, by setting 
to 24 bits and using the generator polynomial 
if 
; and by setting 
to 16 bits and using the generator polynomial 
otherwise.
The bits after CRC attachment are denoted by 
, where 
.