Patent ID: 7420957

Claim:
A mobile terminal for measuring a carrier to noise and interference ratio (CNIR) of a subchannel in an orthogonal frequency division multiplexing (OFDM) mobile communication system, the mobile terminal comprising: a frequency offset and frame detector for detecting frame timing information and frequency offset from a received signal; a demodulator for demodulating the received signal by using the frame timing information and frequency offset detected by the frequency offset and frame detector; a subchannel separator for separating a data symbol from symbols outputted by the demodulator, the data symbol corresponding to a subchannel allocated to a corresponding mobile terminal; a channel estimating and equalizing unit for estimating and equalizing a channel for the corresponding subchannel from the data symbol separated from the subchannel separator and outputting the channel; and a CNIR measuring unit for measuring the current CNIR based on a difference between a predetermined reference symbol and the data symbol outputted from the channel estimating and equalizing unit and transmitting the current CNIR to the base station, and using the measured CNIR to determine the predetermined reference symbol used for measuring a subsequent CNIR, the CNIR measuring unit selecting one among the data symbol from the channel estimating and equalizing unit and the predetermined pilot between the base station and the mobile terminal as the predetermined reference symbol according to whether the previously measured CNIR is greater than a predetermined threshold value.