the present invention relates to a method for transmitting a data demodulation reference signal in a radio mobile communication system . the method comprises : a step for generating a sub - frame including the data demodulation reference signal , and a step for transmitting the generated sub - frame . the 1st and 2nd demodulation reference signal pattern groups include plural demodulation signal patterns orthogonal to each other , and are differentiated from each other with regard to time - frequency resources . in the data demodulation reference signal , demodulation reference signal patterns which are respectively orthogonal to each other m and n − m times are respectively included in the 1st and 2nd demodulation reference signal pattern groups if the rank is n .