  High-frequency communication systems bring extremely large aperture arrays
(ELAA) and large bandwidths, integrating localization and (bi-static) sensing
functions without extra infrastructure. Such systems are likely to operate in
the near-field (NF), where the performance of localization and sensing is
degraded if a simplified far-field channel model is considered. However, when
taking advantage of the additional geometry information in the NF, e.g., the
encapsulated information in the wavefront, localization and sensing performance
can be improved. In this work, we formulate a joint synchronization,
localization, and sensing problem in the NF. Considering the array size could
be much larger than an obstacle, the effect of partial blockage (i.e., a
portion of antennas are blocked) is investigated, and a blockage detection
algorithm is proposed. The simulation results show that blockage greatly
impacts performance for certain positions, and the proposed blockage detection
algorithm can mitigate this impact by identifying the blocked antennas.
