Research Of The Detection Algorithm For WiMAX OFDMA Periodical Ranging

WiMAX which the Physical layer adopt OFDMA method is a potential technology of wireless metropolitan network. As a method of the adjustment of time offset, power information and carrier frequency offset in the uplink, ranging plays an important role in the system. There are three kinds of algorithms for the detection of ranging codes in the OFDMA system. The algorithms are time-domain correlation, frequency-domain correlation and differ-correlation respectively. They utilize the peak value of the correlation to make out the time-departure of MS. At the mean time, the peak value reflects the power information of MS. We can make use of the information to adjust the power of MS. Through the research of the detection algorithm of the periodical ranging access, time-domain correlation, frequency-domain correlation and differ-correlation are discussed. The principle and the process of deduce are provided, and the last two algorithms are realized in the platform of the uplink simulation. Through the tests in different environment and different schemes, the comparison of the two algorithms is presented. The conclusion is that the fake alarm of detection of non-target code of frequency-domain correlation algorithm is a little lower than differ-correlation algorithm when the detective error rate remains equal. Therefore, frequency-domain correlation algorithm is established as the detection method of periodical ranging access in the simulation platform of uplink.