A communication receiving device is provided. The communication receiving device includes a cross-correlation measuring circuit which receives an L-SIG (Legacy signal) symbol and a RL-SIG symbol to measure a cross-correlation degree therebetween, an accumulating circuit which accumulates a real part of a cross-correlation degree measurement value, a comparator which compares the accumulated L-SIG symbol and the RL-SIG symbol with a variable threshold value, and a threshold value calculator for calculating the threshold value.