Embodiments of the present invention provide a communication method, user equipment, and a single radio controller. The method includes: establishing, by user equipment, a first connection with an SRC by using a first communications network; and sending, by the user equipment, NAS signaling or Layer 3 signaling of a second communications network to the SRC by using the first connection, and/or receiving NAS signaling or Layer 3 signaling of a second communications network from the SRC by using the first connection, where the first communications network and the second communications network use different RATs, and the SRC is configured to manage radio resources of the first communications network and the second communications network. Therefore, in the embodiments of the present invention, NAS/L3 signaling of a second communications network is transmitted over the first connection that is established in a first communications network, so that a service can flexibly switch between different RATs, and the system efficiency is improved.