Mobile communication method and radio terminal

Abstract

A mobile communication method, which configures a DRX cycle having an On duration in which a downlink signal transmitted from a serving base station is to be monitored and an Off duration other than the On duration in an RRC connected state where an RRC connection is established between a radio terminal and a radio base station, the mobile communication method comprising: a step A of transmitting, from the radio terminal to the radio base station, a timing adjustment request uplink signal through an uplink control channel, even when a radio resource of an uplink data channel has not been assigned in a case where the DRX cycle is configured; and a step B of transmitting, from the radio base station to the radio terminal, transmission timing correction information of an uplink signal, in response to the timing adjustment request uplink signal.

What is claimed is: 
     
         1 . A mobile communication method, which configures a DRX cycle having an On duration in which a downlink signal transmitted from a serving base station is to be monitored and an Off duration other than the On duration in an RRC connected state where an RRC connection is established between a radio terminal and a radio base station, the mobile communication method comprising:
 a step A of transmitting, from the radio terminal to the radio base station, a timing adjustment request uplink signal through an uplink control channel, even when a radio resource of an uplink data channel has not been assigned in a case where the DRX cycle is configured; and   a step B of transmitting, from the radio base station to the radio terminal, transmission timing correction information of an uplink signal, in response to the timing adjustment request uplink signal.   
     
     
         2 . The mobile communication method according to  claim 1 , wherein the step A comprises: a step of transmitting, from the radio terminal to the radio base station, the timing adjustment request uplink signal, when a movement speed of the radio terminal exceeds a predetermined threshold value. 
     
     
         3 . The mobile communication method according to  claim 1 , comprising:
 a step C of deciding, at the radio base station, a maximum reception interval, in which the transmission timing correction information is to be received, based on a movement speed of the radio terminal; and   a step D of transmitting, from the radio base station to the radio terminal, the maximum reception interval.   
     
     
         4 . The mobile communication method according to  claim 3 , wherein the step A comprises: a step of transmitting, from the radio terminal to the radio base station, the timing adjustment request uplink signal, before a reception interval of the transmission timing correction information exceeds the maximum reception interval. 
     
     
         5 . A radio terminal configured to receive a downlink signal in a mobile communication system, which configures a DRX cycle having an On duration in which the downlink signal transmitted from a serving base station is to be monitored and an Off duration other than the On duration in an RRC connected state where an RRC connection is established between the radio terminal and a radio base station, the radio terminal comprising:
 a control unit configured to transmit a timing adjustment request uplink signal to the radio base station through an uplink control channel, even when a radio resource of an uplink data channel has not been assigned in a case where the DRX cycle is configured.