Methods, systems, and devices for wireless communications are described. A user equipment (UE) may communicate with a first base station using a first antenna array of a set of antenna arrays of the UE. The UE may receive, from the base station, an indication that the UE is to use a second antenna array of the set of antenna arrays to transmit a random access signal. The UE may transmit, to the first base station or a second base station, the random access signal using the second antenna array based on the received indication. The UE may transmit the random access signal to the first base station as part of determining an updated timing advance (TA) value for the second antenna array. The UE may transmit the random access signal to the second base station as a part of initial access or handover.