A method for controlling data retransmission in a multi-user system , the method comprising: determining whether data transferred by at least one but not all of multiple users are received unsuccessfully, wherein the multiple users share a same resource in a feedback channel for carrying feedback information of whether or not data transferred by respective users are received successfully; and when data transferred by at least one but not all of the multiple users are received unsuccessfully, causing data retransmission in a first retransmission mode or a second retransmission mode, wherein causing data retransmission comprises: selecting the first retransmission mode or the second retransmission mode for the data retransmission according to a predetermined scheme, wherein the predetermined scheme is defined based on at least one of the following: a ratio of the number of users whose data are received successfully, to the number of the multiple users ; an amount of available resources in a control channel; and a probability that resource collisions in the feedback channel occur, wherein in the first retransmission mode, positive feedback is sent via the same resource to the multiple users , and adaptive retransmission is triggered for the users whose data are received unsuccessfully, and in the second retransmission mode, negative feedback is sent via the same resource to the multiple users so that non-adaptive retransmission is triggered for the multiple users . determining whether data transferred by at least one but not all of multiple users are received unsuccessfully, wherein the multiple users share a same resource in a feedback channel for carrying feedback information of whether or not data transferred by respective users are received successfully; and when data transferred by at least one but not all of the multiple users are received unsuccessfully, causing data retransmission in a first retransmission mode or a second retransmission mode, wherein causing data retransmission comprises: selecting the first retransmission mode or the second retransmission mode for the data retransmission according to a predetermined scheme, wherein the predetermined scheme is defined based on at least one of the following: a ratio of the number of users whose data are received successfully, to the number of the multiple users ; an amount of available resources in a control channel; and a probability that resource collisions in the feedback channel occur, wherein in the first retransmission mode, positive feedback is sent via the same resource to the multiple users , and adaptive retransmission is triggered for the users whose data are received unsuccessfully, and in the second retransmission mode, negative feedback is sent via the same resource to the multiple users so that non-adaptive retransmission is triggered for the multiple users . a ratio of the number of users whose data are received successfully, to the number of the multiple users ; an amount of available resources in a control channel; and a probability that resource collisions in the feedback channel occur, wherein in the first retransmission mode, positive feedback is sent via the same resource to the multiple users , and adaptive retransmission is triggered for the users whose data are received unsuccessfully, and in the second retransmission mode, negative feedback is sent via the same resource to the multiple users so that non-adaptive retransmission is triggered for the multiple users . <EOS>