Systems, devices, and techniques for antenna port configuration in wireless communication systems are described. A described technique performed by a user equipment (UE) includes receiving configuration information that determines a bit-width value for an antenna port indication field of a downlink control information (DCI) format; receiving a DCI message that is in accordance with the DCI format; and determining an antenna port configuration for one or more demodulation reference signals based on the DCI message, the configuration information, and the bit-width value.