Patent ID: 7733834

Claim:
A frame detection method in multipath channel conditions in an 802.11 transmission which includes 802.11a and 802.11b frames, comprising: detecting a signal in said transmission, wherein the detected signal includes symbols; calculating DCC (delayed copy correlation) values of the received symbols until an end of a timeout period; normalizing the calculated DCC values with power of incoming samples in the transmission; comparing the normalized DCC values with a predetermined threshold th dcc ; declaring that there is a 802.11a frame detected when a certain number of DCC values, th dcnt , exceeds said predetermined threshold th dcc in a window of T consecutive DCC values; and, using periodicity of Barker sequence correlation peaks for identifying occurrence of 802.11b frames in the transmission, wherein identifying the occurrence of 802.11b frames comprises: performing a sliding local copy correlation (LCC) of the incoming samples in the transmission with the Barker sequence; normalizing the LCC values with power of the incoming samples; considering a Barker window of the normalized LCC values at a time, wherein the Barker window corresponds to length of the Barker sequence; comparing the normalized LCC values of the incoming samples of the transmission against a predetermined threshold th lcc ; maintaining a counter having an array corresponding to each position in the Barker window, wherein the counter comprises the array equal to the length of the Barker sequence; incrementing the counter at the position corresponding to the normalized LCC value of the incoming sequence with Barker code which exceeds said threshold th lcc ; repeating the steps of comparing and incrementing for num_corr Barker windows, wherein the num_corr represents the number of the Barker windows used; and comparing a maximum value of the counter array against a predetermined threshold th lcnt , and if the compared maximum value of the counter array exceeds said threshold th lcnt in a predetermined number of Barker windows num corr, then declaring an 802.11b packet.