A novel preamble design for Multi-Cell OFDMA Downlink Systems

In this paper a novel preamble is designed for Multi-Cell Orthogonal Frequency Division Multiple Access downlink system, in which multiple carrier frequency offset exists between mobile station and multiple base stations. The preamble preceded downlink frame from every base station manifests 4-period pattern in one OFDMA symbol by modulating cell/sector ID specific sequence on one of every four subcarriers. This structure enables application of MUSIC algorithm to estimate up to three carrier frequency offset. Liu& Lin´s method, namely increasing the interval of cyclic prefix to form approximately the same four-segment preamble, fails in case of three CFOs. Whereas the estimation algorithm based on the new preamble structure has low complexity and better performance.