Method and apparatus for allocating time slots in a time division duplex communication system. First and second types of time slots selected from receiving and transmitting type time slots are allocated as the first and second time slots, respectively, in a current frame. Based on an amount of information to be transferred, it is determined whether at least one time slot following the second time slot of the frame should be allocated as the first type of time slot, and if so, the last time slot of the frame is always allocated as the first type of time slot, whereby the last time slot of the frame and the first time slot of a succeeding frame are of the same type. If an additional time slot(s) is allocated for the second type of time slot, the third slot is always designated for the second type.