Methods and architectures are described to allow concurrent operation of two separate, non-synchronized, radio systems utilizing closely spaced frequency bands, such as IEEE 802.11p and LTE-V2X, or NR-V2X vehicular communications systems, with a common antenna. A full duplex-“like” active interference cancellation process may be employed that includes self-interference cancellation in the RF domain, in the analog domain and the digital baseband domain to reduce complexities and costs of stringent antenna isolation, otherwise required, for a simultaneous TX and RX mode of operation and concurrent RX mode of operation in closely spaced frequency resources.