  In this paper, an indoor robot navigation system is investigated, where an
intelligent reflecting surface (IRS) is employed to enhance the connectivity
between the access point (AP) and robotic users. Both single-user and
multiple-user scenarios are considered. In the single-user scenario, one mobile
robotic user (MRU) communicates with the AP. In the multiple-user scenario, the
AP serves one MRU and one static robotic user (SRU) employing either
non-orthogonal multiple access (NOMA) or orthogonal multiple access (OMA)
transmission. The considered system is optimized for minimization of the
travelling time/distance of the MRU from a given starting point to a predefined
final location, while satisfying constraints on the communication quality of
the robotic users. To this end, a radio map based approach is proposed to
exploit location-dependent channel propagation knowledge. For the single-user
scenario, a channel power gain map is constructed, which characterizes the
spatial distribution of the maximum expected effective channel power gain of
the MRU for the optimal IRS phase shifts. Based on the obtained channel power
gain map, the communication-aware robot path planing problem is solved by
exploiting graph theory. For the multiple-user scenario, a communication rate
map is constructed, which characterizes the spatial distribution of the maximum
expected rate of the MRU for the optimal power allocation at the AP and the
optimal IRS phase shifts subject to a minimum rate requirement for the SRU. The
joint optimization problem is efficiently solved by invoking bisection search
and successive convex approximation methods. Then, a graph theory based
solution for the robot path planning problem is derived by exploiting the
obtained communication rate map. Our numerical results verify the effectiveness
of the proposed designs.
