Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a base station may implement polar coding to generate codewords for transmission, for example, in a physical broadcast channel (PBCH). The base station may identify a subset of the bandwidth allocated for PBCH transmission (e.g., corresponding to a bandwidth for a synchronization signal), and may assign sub-channels to information bits based on the identified bandwidth subset. The base station may generate a codeword based on the assigned sub-channels, and may map a subset of encoded bits for the codeword to the subset of the bandwidth such that the subset of encoded bits includes bits corresponding to the assigned subchannels for the information bits. A user equipment (UE) may receive the encoded bits in the subset of the bandwidth, and may decode the subset of encoded bits to determine the information bits.