A cloud radio access network system includes remote signal sources, a baseband processing unit pool, an access management server, a software defined network controller and a network signal forwarder. The software defined network controller is electrically connected to the access management server and the network signal forwarder. The network signal forwarder includes at least two network connectors, each of which is configured to be connected to one remote signal source or the baseband processing unit pool. The software defined network controller obtains connection relation between the network connectors and the remote signal sources or the baseband processing unit pool, and provides network resource information to the network signal forwarder according to the connection relation. The network signal forwarder establishes communication between one remote signal source and the baseband processing unit pool according to the network resource information.