Methods, systems, and devices for wireless communications are described in which a transmitting user equipment (UE) may determine a data packet to transmit to another UE and determine a set of candidate resources for transmission of the data packet based on a set of time-frequency resources that are allocated for UE-to-UE communications. A resource reservation signal (RRS) may be transmitted to indicate to other UEs that the set of candidate resources have been reserved by a UE. The RRS may be transmitted such that the RRS may be differentiated from other regular transmissions based at least in part on information provided by a control channel associated with the RRS or a payload of a transmission that includes the RRS. The RRS may indicate one or more of a size of an allocation of the resources and multiple locations of the resources within a time-frequency resource pool.