Analysis of target multipaths in WiFi-based passive radars

摘要

In this study, the authors investigate the effects on the range measurement accuracy of a WiFi-based passive radar when multiple copies of signal, from the same target, are received due to propagation through a rich-scattering environment. These multipath returns from stationary scatters induced range measurement inaccuracies in passive radars including offset of the target from its true range, smearing of the target in range dimension or appearance of ghost targets. Relationship between range measurement inaccuracies due to target multipaths and range resolution of transmission waveform has been studied. A two-step solution, that is, signal separation followed by equalisation, is also proposed to mitigate the effects of multipaths in WiFi-based passive radars.