A wireless node, such as a relay node, has different operating modes for unicast and broadcast/multicast subchannels. For unicast services the phase offsets of those relay nodes engaged in a cooperative transmission are optimized for the subchannels used for unicast services. Alternatively, when no feedback is available and an open loop MIMO or MIMO-type scheme is in use, retransmissions are performed in such a way that a destination (e.g., user terminal) receives effectively a distributed space-time block code. For the broadcast/multicast services time varying random phase offsets may be employed for the subchannels used for broadcast services. For reliable high data rate broadcast transmissions a cooperative retransmission scheme that effectively forms distributed space-time block codes may be used.