  Deployment of small cells in dense urban areas dedicated to the heterogeneous
network (HetNet) and associated relay nodes for improving backhauling is
expected to be an important structural element in the design of beyond 5G (B5G)
and 6G wireless access networks. A key operational aspect in HetNets is how to
optimally implement the wireless backhaul links to efficiently support the
traffic demand. In this work, we utilize the recently proposed Robotic Aerial
Small Cells (RASCs) that are able to grasp at different tall urban landforms as
wireless relay nodes for backhauling. This can be considered as an alternative
to fixed small cells (FSCs) which lack flexibility since once installed their
position cannot be altered. More specifically, on-demand deployment of RASCs is
considered for constructing a millimeter-wave (mmWave) backhaul network to
optimize available network capacity using a network flow-based mixed integer
linear programming (MILP) formulation. Numerical investigations reveal that for
the same required achievable throughput, the number of RASCs required are 25\%
to 65\% less than the number of required FSCs. This result can have significant
implications in reducing required wireless network equipment (capex) to provide
a given network capacity and allows for an efficient and flexible network
densification.
