Frame synchronization using superimposed sequences

We present a new technique for synchronizing frames of length n, using a sync sequence of the same length n with good cyclic autocorrelation properties. This sequence is modulated and superimposed on the modulated data sequence. The energy of the modulated sync sequence is uniformly distributed and small compared to the energy of the data sequence. For AWGN channels, we give a general upper bound on the correct frame synchronization probability as a function of the frame length and the signal-to-noise ratio. The new technique approaches this upper bound to less than 1 dB, and outperforms standard methods. For fading channels the performance is considerably better than for the standard methods. By increasing the frame length n, the correct frame synchronization probability becomes nearly the same as for AWGN channels