  In this article we propose solutions to diverse conflicts that result from
the deployment of the (still immature) relay node (RN) technology in LTE-A
networks. These conflicts and their possible solutions have been observed by
implementing standard-compliant relay functionalities on the Vienna simulator.
  As an original experimental approach, we model realistic RN operation, taking
into account that transmitters are not active all the time due to half-duplex
RN operation. We have rearranged existing elements in the simulator in a manner
that emulates RN behavior, rather than implementing a standalone brand-new
component for the simulator. We also study analytically some of the issues
observed in the interaction between the network and the RNs, to draw
conclusions beyond simulation observation.
  The main observations of this paper are that: $i$) Additional time-varying
interference management steps are needed, because the LTE-A standard employs a
fixed time division between eNB-RN and RN-UE transmissions (typical relay
capacity or throughput research models balance them optimally, which is
unrealistic nowadays); $ii$) There is a trade-off between the time-division
constraints of relaying and multi-user diversity; the stricter the constraints
on relay scheduling are, the less flexibility schedulers have to exploit
channel variation; and $iii$) Thee standard contains a variety of parameters
for relaying configuration, but not all cases of interest are covered.
