  Emerging systems such as Internet-of-things (IoT) and machine-to-machine
(M2M) communications have strict requirements on the power consumption of used
equipments and associated complexity in the transceiver design. As a result,
multiple-input multiple-output (MIMO) solutions might not be directly suitable
for these system due to their high complexity, inter-antenna synchronization
(IAS) requirement, and high inter-antenna interference (IAI) problems. In order
to overcome these problems, we propose two novel index modulation (IM) schemes,
namely pulse index modulation (PIM) and generalized PIM (GPIM) for single-input
single-output (SISO) schemes. The proposed models use well-localized and
orthogonal Hermite-Gaussian pulses for data transmission and provide high
spectral efficiency owing to the Hermite-Gaussian pulse indices. Besides, it
has been shown via analytical derivations and computer simulations that the
proposed PIM and GPIM systems have better error performance and considerable
signal-to-noise ratio (SNR) gain compared to existing spatial modulation (SM),
quadrature SM (QSM), and traditional M-ary systems.
