Patent ID: 7583966
Filing Date: 2009-09-01
Classification: H04W

Abstract:
1. A mobile communications system including a mobile terminal, a plurality of base stations each of which sets up a radio channel to the mobile terminal, and a radio network controller which is connected to each of the base stations and includes an active set for the mobile terminal, which shows a list of cells in which the radio channel is being established to the mobile terminal for handover, said mobile communication system wherein: said mobile terminal transmits a radio channel setup request, when detecting signal power of a downlink reference signal from a neighboring cell is higher than an active set addition threshold level, for requesting to establish the radio channel in the neighboring cell and to add the neighboring cell to the active set of the mobile terminal; said base station transmits a radio channel release request, when degradation of communication quality of an uplink signal from the mobile terminal is detected in a predetermined condition, for requesting to release the radio channel from the mobile terminal in own cell and to delete own cell from the active set of the mobile terminal; said radio network controller, by receiving the radio channel release request, releases the radio channel for the mobile terminal in the cell which relates to the radio channel release request and deletes the cell from the active set of the mobile terminal, and then, upon receiving the radio channel set up request from the mobile terminal, ignores the radio channel set up request if the radio channel setup request relates to the same cell which has been deleted from the active set of the same mobile terminal transmitting the radio channel setup request and if the radio channel setup request is received before a predetermined time has elapsed after deletion of the cell from the active set; and wherein, after the radio network controller has deleted the cell from the active set of the mobile terminal by the radio channel release request from the base stations, and then, upon receiving the radio channel set up request from the mobile terminal, the radio network controller accepts the radio channel setup request and sets up the radio channel based on the radio channel set up request and adds the cell to the active set of the mobile terminal if the radio channel set up request is received after the predetermined time has elapsed after deletion of the cell from the active set even though the radio channel setup request relates to the same cell which has been deleted from the active set of the same mobile terminal transmitting the radio channel setup request.