A communication apparatus and method for performing discontinuous reception in a mobile communication system is provided. The communication apparatus continues to turn on a receiver during a reception-on (Rx-on) period associated with persistent resource allocation to receives a packet, and receives a retransmission packet transmitted through the persistent resources at the Rx-on period spaced from the Rx-on period by a processing time of the retransmission packet given taking into account feedback information determined according to a reception error of the packet.