  In this study, we propose a wideband index modulation (IM) based on
circularly-shifted chirps. To derive the proposed method, we first prove that a
Golay complementary pair (GCP) can be constructed by linearly combining the
Fourier series of chirps. We show that Fresnel integrals and/or Bessel
functions, arising from sinusoidal and linear chirps, respectively, can lead to
GCPs. We then exploit discrete Fourier transform-spread orthogonal frequency
division multiplexing (DFT-s-OFDM) to obtain a low-complexity transmitter and
receiver. We also discuss its generalization for achieving a trade-off between
peak-to-mean envelope power ratio (PMEPR) and spectral efficiency (SE). Through
comprehensive simulations, we compare the proposed scheme with DFT-s-OFDM with
IM, orthogonal frequency division multiplexing (OFDM) with IM and complementary
sequences (CSs) from Reed-Muller (RM) code. Our numerical results show that the
proposed method limits the PMEPR while exploiting the frequency.
