A radio access network system, comprising: a first device , a second device , and a third device ; wherein the first device is configured to receive, by using an air interface, a first data from a terminal covered by the radio access network system and to process the first data at a first-part air interface protocol stack; the second device comprises a transceiver module and a processing module , wherein the transceiver module is configured to receive the first data from the first device in the radio access network system, and the processing module is configured to process, at a second-part air interface protocol stack, the first data received by the transceiver module ; wherein the transceiver module is further configured to send the processed first data to the third device in the radio access network system, and receive second data from the third device ; and the processing module is further configured to process, at the second-part air interface protocol stack, the second data received by the transceiver module , and send the processed second data to the first device ; wherein the first-part air interface protocol stack comprises a physical, PHY, layer, a Medium Access Control, MAC, layer, and a Radio Link Control, RLC, layer, and the second-part air interface protocol stack comprises a Packet Data Convergence Protocol, PDCP, layer; wherein the first device is an access node in the radio access network system, the second device is a user plane anchor of the first device , and the third device is a control plane anchor of the first device ; and wherein the first data is a RRC connection request, and the second data is a RRC connection setup message. the first device is configured to receive, by using an air interface, a first data from a terminal covered by the radio access network system and to process the first data at a first-part air interface protocol stack; the second device comprises a transceiver module and a processing module , wherein the transceiver module is configured to receive the first data from the first device in the radio access network system, and the processing module is configured to process, at a second-part air interface protocol stack, the first data received by the transceiver module ; wherein the transceiver module is further configured to send the processed first data to the third device in the radio access network system, and receive second data from the third device ; and the processing module is further configured to process, at the second-part air interface protocol stack, the second data received by the transceiver module , and send the processed second data to the first device ; wherein the first-part air interface protocol stack comprises a physical, PHY, layer, a Medium Access Control, MAC, layer, and a Radio Link Control, RLC, layer, and the second-part air interface protocol stack comprises a Packet Data Convergence Protocol, PDCP, layer; wherein the first device is an access node in the radio access network system, the second device is a user plane anchor of the first device , and the third device is a control plane anchor of the first device ; and wherein the first data is a RRC connection request, and the second data is a RRC connection setup message. <EOS>