Methods and apparatus for transmitting and receiving data over a physical channel using a polar code are provided. The polar code defines a plurality of virtual channels within the physical channel and allocates a subset of the virtual channels for the transmission of data. The method for transmitting data: receives a block of data to be transmitted; receives additional data to be transmitted together with the block of data; selects one or more of the virtual channels; determines a scrambling sequence based on the additional data; applies the scrambling sequence to those bits of the block of data to generate a scrambled version of the block of data; and transmits the scrambled version of the block of data according to the polar code.