An apparatus for archiving robust channel estimation in a communication system includes a training sequence generator to generate a training sequence. A formatter inserts the training sequence to a frame. A transmitting module is employed to transmit the frame. The training sequence generator further includes a symbol generator to generate a plurality of training symbols satisfying a predetermined constraint such that the training symbols are insensitive to synchronization error and a training sequence forming unit that forms the training sequence from the training symbols generated by the training symbol generator.