Wireless devices in a wireless network may use multiple communication modes to perform device-to-device (D2D) communication in a mesh wide area network (WAN). For instance, one communication mode may be contention-based, while the other communication mode may be scheduled (e.g., by a relay). To facilitate co-existence between these communication modes, a wireless device may identify a set of resources set aside for D2D communications and may select and reserve a transmission time interval (e.g., a slot) of the D2D resources. Other wireless devices may determine the transmission time interval is reserved and refrain from transmitting during that transmission time interval. In another example, a base station may assign a D2D communication mode to certain sets of D2D resources.