According to a detailed embodiment of the invention, the RS implements the following operations by using each of M shift parameter groups: Based on M shift parameters in the group, shifting respectively M decoded bit streams and merge the M shifted bit steams to get a check bit stream. Consequently M check bit streams are obtained by using M shift parameter groups. Then the RS transmits M check bit streams to the BS. The BS has received the M uplink signals from mobile terminals before and makes the M check bit streams as the check information of those uplink signals in order to check them better and reduce error rate. By adopting the method and device proposed by the invention, it is ensured in the low SNR regime error user rate or error block rate is more ideal in multi-user detection in the BS.