Waveform Based on ZAC Sequences

We propose a waveform wherein orthogonal basis functions are constructed from cyclically shifted versions of a zero autocorrelation (ZAC) sequence. It is shown that the waveform can equivalently be represented as filtered discrete Fourier transform spread OFDM (DFT-s-OFDM). Chirp sequences are one type of ZAC sequence, however, they have high implementation complexity, and we utilize simpler biphase ZAC sequences instead. The results show that lower error rates on time-frequency selective channels are obtained than for orthogonal frequency division multiplexing (OFDM) and DFT-s-OFDM. We derive correlation properties and find that the waveform is also suitable as a synchronization signal, since modulation symbols can be chosen to obtain an ideal periodic autocorrelation function (PACF) and low peak-to-average-power ratio (PAPR).