Radio localization is a key enabler for joint communication and sensing in the fifth/sixth generation (SG/6G) communication systems. With the help of multipath components (MPCs), localization and mapping tasks can be done with a singlebase station (BS) and single unsynchronized user equipment (UE) if both of them are equipped with an antenna array. However, the antenna array at the UE side increases the hardware and computational cost, preventing localization functionality. In thiswork we show that with Doppler estimation and MPCs, localization and mapping tasks can be performed even with a single antenna mobile UE. Furthermore, we show that the localization and mapping performance will improve and then saturate ata certain level with an increased UE speed. Both theoretical Cramer-Rao bound analysis and simulation results show the potential of localization under mobility and the effectiveness of the proposed localization algorithm. © 2022 IEEE