A method includes determining statics indicators of a first communication device when communicating with a plurality of communication groups comprising the first communication device and at least one second communication device; generating a plurality of multi-user level statics of a plurality of multi-user levels according to the static indicators corresponding to each multi-user level, wherein each multi-user level comprises communication groups with a given number of communication devices; adjusting a plurality of group offsets of the plurality of communication groups according to the plurality of multi-user level statics and current modulation and coding scheme of the first communication device in the plurality of communication groups; and adjusting initial MCSs of the first communication device and the second communication device in each communication group by the group offset of each communication group, to acquire the current MCSs of the first communication device and the second communication device of each communication group.