Matched nonlinearities for frame synchronisation in presence of frequency offsets

In communication systems data are transmitted in frames. The frame boundaries are indicated by transmitting a number of a priori known symbols. The process of detecting the frame boundaries is essential to correct data reception at the receiver. Frame synchronisation also frequently needs to be achieved prior to carrier frequency synchronisation. A number of techniques that achieve frame synchronisation prior to carrier synchronisation have been described in the technical literature. It is shown that matched nonlinearities can be used to improve the performance of the best performing, maximum-likelihood based frame synchroniser known in the literature, by about 1 dB in required signal-to-noise ratio, for the same accuracy in frame synchronisation, with essentially the same implementation complexity.