In this paper we evaluate the impact of UWB transmissions on the performances of a WiMAX receiver, which employs orthogonal frequency-division multiplexing (OFDM) modulation and operates in a time division duplex (TDD) mode. To this aim, we compute the interference contribution caused by DS-UWB signals at the WiMAX receiver output, as well as the interference statistics, adopting a theoretical approach and simulations. We present a non-cooperative detect and avoid (DAA) procedure to mitigate the UWB interference to WiMAX. The results of the interference analysis are exploited to opportunely set the UWB transmission parameters in the DAA procedure, so that the targeted QoS is achieved for the WiMAX communications.