A method of operating a wireless communication device (101) includes receiving (3002) at least one downlink control message (411, 412, 4002) from a communications network (100), the at least one downlink control message (411, 412, 4002) being indicative of a frequency density (401-404) of uplink reference signals (31), the uplink reference signals (31) being for an estimation of a radio channel (114) between the wireless communication device (101) and the communications network (100) to coherently decode data signals encoding data of a uplink data transmission (4012), the uplink reference signals (31) and the data signals using the same precoding. The method also includes transmitting (3003) the uplink reference signals (31) on the radio channel (114) using a time-frequency resource mapping (390) set in accordance with the frequency density (401-404), the time-frequency resource mapping (390) allocating time-frequency resource elements (311, 312, 313) of a plurality of time-frequency resource elements (309, 311, 312, 313) of a time-frequency resource grid (300) of the radio channel (114) to the uplink reference signals (31).