  The fundamental problem of energy-efficient reallocation of mobile random
sensors to provide full coverage without interference is addressed in this
paper. We consider $n$ mobile sensors with identical sensing range placed
randomly on the unit interval and on the unit square. The main contribution is
summarized as follows:
  If the sensors are placed on the unit interval we explain the sharp increase
around the sensing radius equal to $\frac{1}{2n}$ and the interference distance
equal to $\frac{1}{n}$ for the expected minimal $a$-total displacement,
  If the sensors are placed on the unit square we explain the sharp increase
around the square sensing radius equal to $\frac{1}{2 \sqrt{n}}$ and the
interference distance equal to $\frac{1}{\sqrt{n}}$ for the expected minimal
$a$-total displacement.
