A packet transmission method in which packets are transmitted between a base station and a mobile station communicating with the base station includes the steps of: recognizing the size of each of the packets to be transmitted; determining a transmission rate for each packet in accordance with the recognized size of the packet; allocating a radio resource to the transmission of each packet between the base station and the mobile station based on the determined transmission rate; and transmitting each packet between the base station and the mobile station using the allocated radio resource. In the method, a modulation method or a radio resource used for transmitting the packets is determined by calculating a transmission rate in a wireless area according to the size of each packet and a transmission request in the wireless area. The transmission request is recognized by the base station from an upper network when the packets are transmitted downward, while calculated by the base station based on a user request and a transmission state of the upper network when the packets are transmitted upward. Therefore, end-to-end quality of service can be provided.