Methods, systems, and devices for wireless communications are described for improving sidelink communication reliability. In some examples, a user equipment (UE) may map allocated sidelink resources from a logical domain to a physical domain, where the mapped resources may include greater frequency diversity in the physical domain A frequency range of a sidelink control channel or of a sidelink data channel may be greater in the physical domain than in the logical domain after the mapping. In some examples, sidelink communications may be associated with an aggregation factor that represents a number of repetitions of a sidelink communication. In this example, a UE may repeat a sidelink communication within a contention-based resource pool a number of times before receiving feedback in order to increase communication reliability. A first UE may communicate a sidelink communication with a second UE using a resource mapping or repetitions of the sidelink communication.