A radio access network comprises a donor base station node (29) and a relay base station node (20). The relay base station node (29) participates in communications across a first radio interface with a wireless terminal (30) and also participates in communications over a backhaul link across a second radio interface, the second radio interface reusing at least some functionality of the first interface. The donor base station node (28) configures a subframe configuration pattern. The subframe configuration pattern is arranged to specify which subframe(s) of a frame structure may be utilized for the backhaul link. As a result of subframe configuration, a HARQ process state in a HARQ process at one of the base station nodes is known by the other base station node by any of several operational modes.