  The ideas of wireless network coding at the physical layer promise high
throughput gains in wireless systems with relays and multi-way traffic flows.
This gain can be ascribed to two principles: (1) joint transmission of multiple
communication flows and (2) usage of \emph{a priori} information to cancel the
interference. In this paper we use these principles to devise new transmission
schemes in wireless cellular systems that feature both users served directly by
the base stations (direct users) and users served through relays (relayed
users). We present four different schemes for \emph{coordinated transmission}
of uplink and downlink traffic in which one direct and one relayed user are
served. These schemes are then used as building blocks in multi-user scenarios,
where we present several schemes for scheduling pairs of users for coordinated
transmissions. The optimal scheme involves exhaustive search of the best user
pair in terms of overall rate. We propose several suboptimal scheduling
schemes, which perform closely to the optimal scheme. The numerical results
show a substantial increase in the system--level rate with respect to the
systems with non--coordinated transmissions.
