Embodiments relate to outer coding in communications between a first network device and a second network device. A transport block (TB) and a first parity code block that is based on contents of the TB are transmitted from the first network device to the second network device. The first network device receives feedback information that is transmitted from the second network device. The feedback information indicates a decoding failure of the TB. The first network device generates a second parity check CB that is based on the contents of the TB and is different from the first parity check CB and transmits the second parity check CB to the second network device. The second network device receives the second parity check CB and performs error detection decoding of the TB based on the second parity check CB.