The present disclosure relates to resource request in wireless communications. According to an embodiment of the present disclosure, a method performed by a first wireless device configured to operate in a wireless communication system, the method comprises: receiving, from a network, one or more sidelink grants; creating a data unit based on the one or more sidelink grants; performing a transmission of the data unit to a second wireless device by using the one or more sidelink grants; transmitting, to the network via a physical uplink control channel (PUCCH), a resource request for a retransmission of the data unit based on a quality of service (QoS) requirement of the data unit; receiving, from the network, one or more sidelink grants for the retransmission of the data unit; and performing the retransmission of the data unit to the second wireless device by using the one or more sidelink grants for the retransmission of the data unit.