Systems and methods for wireless communications are disclosed herein. Example implementations include a wireless communication method of dividing, by a wireless communication device, an uplink transmission into a plurality of virtual uplink transmissions based on one or more time-domain parameters, and determining, by the wireless communication device for each of the plurality of virtual uplink transmissions, respective time-domain positions of one or more demodulation reference signals. Example implementations also include a wireless communication method of determining, by a wireless communication device, a number of valid symbols for an uplink transmission, and determining, by the wireless communication device for the uplink transmission, respective time-domain positions of one or more demodulation reference signals.