Single Tx and dual Rx dual-SIM dual-active features can connect two separate networks at the same time using a single transmit chain through a timesharing schedule. The timesharing schedule sets the priority of the two simultaneous connections and assigns the user equipment uplink time slots to transmit data based on preference of the two simultaneous connections. Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS), two concurrent radio access technologies, are considered for performance evaluations. The UMTS uplink has a blank transmission because of lower priority assumption when the GSM uplink sends data simultaneously. This causes a degradation in UMTS performance. Thus a mitigation scheme for the UMTS uplink is proposed to minimise performance loss.