Described herein are technologies related to an implementation of interference mitigation in a receiver of a portable device. A preemptive-automatic gain control (AGC) system mitigates a collocated or external interfering signal in a receiver of a portable device. The receiver of the portable device receives and processes a data packet of a first radio frequency (RF) signal that includes a Bluetooth (BT) signal, a Wi-Fi signal, a near field communications (NFC), 3G, 4G, or the like. During the processing of the data packet, a collocated or an external second RF signal is detected and received by the receiver. The second RF signal includes an interfering Bluetooth (BT) uplink transmission, a near field communications (NFC) transmission signal, a Wi-Fi transmission signal, 3G or 4G uplink transmission, an LTE signal, or the like.