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Abstract

A data communication apparatus and method based on orthogonal frequency division multiple access (OFDMA) are provided. In the data communication apparatus, a (U+1)-th encoder in a u-th user transmitting unit among U user transmitting units which transmit corresponding user information to a base station part encodes the user information and outputting the result of encoding as N.sub.u u-th user symbols. A user signal generator generates a u-th user signal x.sub.k.sup.(u) in a temporal domain from the u-th user symbol A.sub.m.sup.(u) received from the (U+1)-th encoder according to a formula, x.sub.k.sup.(u)=a.sub.k % N.sub.u.sup.(u) exp(j2.pi.kn.sub.u/N). A second cyclic extension symbol inserter inserts a cyclic extension symbol into the u-th user signal. A second signal transmitter converts the result of insertion into a symbol block signal and transmitting the symbol block signal to the base station part. Here, 1.ltoreq.N.sub.U

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