  The terahertz band is considered the last frontier for wireless
communications and expected to play a significant role in beyond 5G networks.
Besides supporting extremely high data rates for existing devices, the
terahertz band is also expected to connect future nanoscale devices using
graphene-based nano-antenna, which happens to radiate in 0.1-10 THz band. In
this band, higher order derivatives of Gaussian pulses can provide
energy-efficient communication for nanodevices. In this paper, we propose a
metric, called root mean square (RMS) frequency spread, to detect the
derivative order of the pulse at the receiving base station using uniform
linear array antennas. Simulation experiments demonstrate that RMS frequency
spread can be used to detect the derivative order of Gaussian pulses with 99%
accuracy for distances up to 50 cm. This finding opens up a new design space
for nanoscale terahertz communication, which can encode information in time
derivative order of the transmitted pulse.
