modulation mode mod k the modulation mode of the k th user such as bpsk qpsk 16qam etc suitable for the channel condition of the user then each modulation symbol is repeated in the symbol repeater 202 205 or 208 l k the number of symbol repetitions of the k th user times each symbol is multiplexed by an orthogonal code c k the orthogonal code of the k th user having a length n code length of an orthogonal user code and then spread into a chip stream the spread chip streams of the users are synchronized with the symbol timing in the combiner 210 and added to each other subsequently m by n interleaving is performed on the chip stream having n number of symbols to be transmitted simultaneously in the m by n interleaver to array the chips for the same symbol at an interval of m chips a system generalizes the overall conditions including traffic condition such as the number of users of the system and the entire system channel condition and then it determines a spreading scheme based on the conditions if the system selects a time based spreading scheme the n by ns chip interleaver 212 performs n by ns ns n u00d7 m interleaving again additionally with respect to the interleaved chip stream ns being the number of sub carriers if the system selects a frequency based spreading.