  Data Fusion of wireless sensors is a common technique employed in many
communication systems. This work focuses on incorporating the principles of
non-orthogonal-multiple-access (NOMA) to optimize error performance directly in
the choice of constellation design. More specifically, the problem of two
sensor data fusion of a binary uniform source sent over a Gaussian multiple
access channel via symmetric binary constellations is investigated. A so-called
planar upper bound on the error probability is analytically derived. A
constellation design is then obtained by establishing in closed form its
rotation parameter that minimizes the upper bound. Simulation results show that
the resulting constellations achieve a near identical performance as
experimentally determined optimal constellations.
