  Drones are envisaged as an important part of the future 6G systems. With the
possibility of their fast deployment they provide additional connectivity
options in form of a hotspot. However, typically in such a use case they
require provisioning of a wireless backhaul link to facilitate their proper
operation, which might be a challenging task in urban environment. One of the
possible ways to connect such nodes is to use the integrate access and backhaul
(IAB) approach, where part of the spectrum dedicated for user access at the
base station is used for wireless backhauling. Thus, in this work we consider
the problem of establishing a multi-hop wireless backhaul link following the
IAB concept, with the aid of drone relay stations (DRSs) and reconfigurable
intelligent surfaces (RISs). We formulate the problem of coverage improvement
with fixed number of relays assuming certain throughput requirements on the
backhaul. We show with simulations that the use of RISs allows for improvement
of coverage in such a scenario or reduction in the number of involved nodes to
provide the required backhaul.
