1. A method operable in a wireless communication network including a first base station and a second base station, both configured for serving user equipment devices (UEs), the method comprising:making a first determination that a data transmission-unit of fixed temporal length transmitted by a UE simultaneously to the first base station on a first uplink air interface and the second base station on a second uplink air interface will be received at the first base station beginning at a first time delay beyond a decoding start time, and at the second base station beginning at a second time delay beyond the decoding start time, wherein the second time delay is greater than both the first time delay and a threshold delay beyond the decoding start time;
making a second determination of a volume of data VD that will temporally fill the data transmission-unit to no greater than a reduced temporal length, the reduced temporal length being the fixed temporal length minus the second time delay;
transmitting information to the UE that causes the UE to use VD when transmitting data in the data transmission-unit to the first and second base stations; and
receiving at the first and second base stations the data transmission-unit transmitted by the UE, the received data transmission-unit containing the volume VD of data.