A transmission method includes: a step A which decides a maximum allowed data size of an upstream user IP packet in accordance with the type of a transmission path connected to a radio base station (60) and reports the size to a mobile station (70); a step B in which the mobile station (70) generates an upper node layer data unit of the reported maximum allowed data size or below; a step C in which the mobile station (70) generates an upstream user IP packet containing the upper node layer data unit, generates radio communication data containing the upstream user IP packet, and transmits the data to the radio base station (60); and a step D in which a radio base station (eNB) generates cabled transmission data containing the upstream user IP packet and transmits the data to the upper node.
