of a zero padding at the beginning. The code length, usually set to $E=G$, has to be changed accordingly, namely setting $E = \lceil G/2 \rceil$.

Mother polar code length and rate matching selection {#subsec:param}
----------------------------------------------------

  -------------------------- ----------------------------------- ------------------------------ ----- ------ ----- -- --
                                                                                                                      
                                                                                                                      
                                                                                                                      
                                    $(A \geq 1013) \vee$                $(A < 360) \vee$                              
                              $(A \geq 360 \wedge G \geq 1088)$   $(A < 1013 \wedge G < 1088)$                        
  Max polar code exponent                 $n_{max}$                                                                   
  Input bits inter. flag                  $I_{IL}$                                                                    
  Channel inter. flag                     $I_{BIL}$                                                                   
  Segmentation flag                       $I_{seg}$                            1                                      
  Max payload length                      $G_{max}$                          16384                     8192   864     
  Min payload length                      $G_{min}$                                                     25    864     
  Max message length                      $A_{max}$                                              140    32            
  Min message length                      $A_{min}$                                               1     32            
  CRC length                                 $L$                                                                      
  \# of PC bits                           $n_{PC}$                                                                    
  \# of row-weight PC bits              $n_{PC}^{wm}$                                             0     1             
  -------------------------- ----------------------------------- ------------------------------ ----- ------ ----- -- --

The mother polar code length $N = 2^n$ is a crucial parameter in the encoding process. Its logarithm $n$ is selected as $$n = \max(\min(n_1,n_2,n_{max}),n_{min})~,$$ where $n_{min}$ and $n_{max}$ give a lower and an upper bound on the mother code length, respectively. In particular, $n_{min} = 5$, while $n_{max} = 9$ for the downlink control channel, and $n_{max} = 10$ for the uplink. Parameter $n_2$ gives an 