Georg Frank

Parameter optimization for decision directed frequency tracking for coherent OFDM

In wireless transmission systems frequency offsets have to be taken care off. OFDM showing otherwise good characteristics in mobile communication reacts sensitively to these offsets. In case of coherent modulation the situation is even worse as here-additionally to the fact that the offsets destroy the orthogonality of the subcarriers-the correct reception of long data frames is impossible due to the rotation of the signal constellation. Frequency tracking is therefore a necessity. This paper enlightens the context of a low-complexity PLL tracking structure for frequency selective transmission environments and shows that when exploiting this knowledge in an analytical optimization a significant improvement of performance and possibly a reduction in complexity can be achieved.