Ambiguity Function analysis of WiMAX transmissions for passive radar

In this paper the feasibility of a WiMAX transmissions based Passive Bistatic Radar (PBR) is analysed. The Ambiguity Function (AF) of the considered waveform of opportunity is characterized with reference to different transmission modes. The signal AF is shown to yield regularly spaced undesired peaks which might strongly limit the target detection capability of a WiMAX-based PBR. These sidelobe structures have a deterministic nature mainly related to the OFDM modulation exploited by WiMAX transmissions. A proper filter, based on the knowledge of the expected value of the signal Autocorrelation Function (ACF), is implemented to cope with this limitations and its performance is evaluated against simulated data generated according to the IEEE 802.16e Standard. The proposed approach is shown to yield an effective removal of the undesired peaks in the AF thus making the considered waveform more attractive for PBR medium range surveillance.