Techniques are described for wireless communication. A first method includes winning, at a UE, contention for access to a channel of a shared radio frequency spectrum band; identifying a number of frequency resources of the band that are allocated to the UE for at least one uplink transmission following the winning contention for access; and transmitting a channel reservation signal using a set of frequency resources associated with the identified number of frequency resources. A second method includes winning, at a UE, contention for access to a channel of a shared radio frequency spectrum band; identifying a number of frequency resources of the band that are pre-designated by a base station for transmission of a channel reservation signal; and transmitting the channel reservation signal, after the winning contention for access, using a set of frequency resources associated with the identified number of pre-designated frequency resources.