Apparatus and method to eastimate noise and interference power in a communication system

An NI electric power estimation device and a method thereof using periodic ranging code in a communication system are provided to improve the overall performance of communication system by estimating exact NI(Noise and Interference) power through periodic ranging code. Multipliers(213,214) produce a correlation values of ranging codes which are usable in the ranging code transmission device. A desired ranging code detector(217) detects ranging codes which the ranging code receiving device desires using correlation values. A remaining ranging code selector(219) selects residual ranging codes, and a correlation value for the residual ranging codes is outputted. The NI power estimator estimate the NI electricity using correlation NI power offsets between the residual ranging codes and the selected ranging codes as described above.