Systems, methods, and instrumentalities are disclosed for error check-based synchronization. Physical Broadcast Channel (PBCH) data may be determined. A scrambling (e.g., a first scrambling) of the PBCH data may be scrambled via a sequence (e.g., a first sequence). The first sequence may be based on a cell ID and/or timing information. Error check bits may be attached to the scrambled PBCH data and to the timing information. The error check bits may include one or more cyclic redundancy check (CRC) bits. The scrambled PBCH data, the timing information (e.g., the unscrambled timing information), and/or the attached error check bits may be polar encoded. The polar encoding may result in polar encoded bits. A scrambling (e.g., a second scrambling) of the polar encoded bits may be scrambled via a sequence (e.g., a second sequence). The first sequence and the second sequence may be different. The polar encoded bits may be transmitted.