Embodiments of the present invention disclose a resource allocation method, a transmission method, and apparatuses. The resource allocation method comprises: sending a scheduling instruction, wherein the scheduling instruction comprises: information that is associated with at least two carriers in an unlicensed spectrum allocated to transmission of a user equipment; determining at least one available carrier in the at least two carriers; and sending a physical indication signal on the at least one available carrier, wherein the physical indication signal is used to occupy the at least one available carrier. According to the method and apparatus of the embodiments of the present invention, at least two carriers is allocated to transmission of a user equipment at a scheduling moment, at least one available carrier in the at least two carriers is determined, and a physical indication signal is used to occupy the at least one available carrier, thereby reducing the possibility of occurrence of the problem of resource unavailability and/or resource waste caused by the unpredictability of whether an unlicensed spectrum is available.