Preamble sequence detection and integral carrier frequency offset estimation method for OFDM/OFDMA wireless communication system

Abstract

In multi-cell OFDM/OFDMA wireless communication systems, any subscriber station (SS) or mobile station (MS) that intends to enter the system needs to establish time and frequency synchronization with the base station (BS) and obtain the identification code of the BS, where in frequency synchronization one usually needs to estimate the fractional carrier frequency offset (CFO) and the integral CFO. (“Fractional” and “integral” refer to, respectively, the fractional and the integral parts of the ratio of the CFO to subcarrier spacing.) The present invention assumes that the SS or MS first does timing and fractional CFO synchronization and then conducts integral CFO estimation and BS identity detection. The present invention considers integral CFO estimation and BS identity detection jointly, i.e., it proposes solutions that address these topics jointly. The present invention formulates the problem as a signal detection problem in multi-channel interference and obtains the theoretically optimal solution first, and then derives simplified, approximately optimal solutions, in which the present invention employs frequency-domain filtering to calculate the required correlation values which can drastically reduce the high computational complexity of the original theoretically optimal solution but results in little impact on precision. In addition, the present invention proposes several further simplified algorithms, some of which can even eliminate the use of multipliers. The above proposition of frequency-domain filtering has high extensibility in application to related signal sequence detection problems.