Patent ID: 7995967

Claim:
In a wireless communication system, a method of establishing communication between a mobile and a base station using a ranging signal, the method comprising: modulating, in the mobile station, ranging signals on at least one ranging subchannel: wherein the ranging subchannel includes multiple subcarrier blocks; wherein subcarriers in each subcarrier block are contiguous in frequency; wherein ranging subchannels associated with the base station employ predetermined block configurations; and a sequence of all modulating signals in a ranging subchannel is a ranging sequence; estimating by the mobile station, using a received downlink signal from the base station, a path loss between the base station and the mobile station; setting a power level of the ranging signals by an open-loop power control, wherein the mobile station adds a negative offset to the open-loop power setting to begin sending the ranging signal and gradually increases power as a number of failures and retries increases; detecting, by the base station, a presence of the ranging signal, a time delay, and the power level, wherein the detection process comprises: applying Fast Fourier Transform (FFT) to a selected window of the ranging signal; correlating, in the frequency-domain, stored ranging sequences with the ranging signal, wherein the correlation is performed segment-wise, and wherein each segment of the correlation is performed on the subcarrier block using a correlation result to detect and identify the ranging signal; and correlating, in the time-domain, the identified ranging signal with a corresponding one of the stored ranging sequences, in a sliding-window fashion, to determine the time delay and power level of the ranging signal.