  We demonstrated a vehicle detection and classification method based on Long
Term Evolution (LTE) communication infrastructure based environment sensing
instrument, termed as LTE-CommSense by the authors. This technology is a novel
passive sensing system which focuses on the reference signals embedded in the
sub-frames of LTE resource grid. It compares the received signal with the
expected reference signal, extracts the evaluated channel state information
(CSI) and analyzes it to estimate the change in the environment. For vehicle
detection and subsequent classification, our setup is similar to a passive
radar in forward scattering radar (FSR) mode. Instead of performing the radio
frequency (RF) signals directly, we take advantage of the processing that
happens in a LTE receiver user equipment (UE). We tap into the channel
estimation and equalization block and extract the CSI value. CSI value reflects
the property of the communication channel between communication base station
(eNodeB) and UE. We use CSI values for with and vehicle and without vehicle
case in outdoor open road environment. Being a receiver only system, there is
no need for any transmission and related regulations. Therefore, this system is
low cost, power efficient and difficult to detect. Also, most of its processing
will be done by the existing LTE communication receiver (UE). In this paper, we
establish our claim by analyzing field-collected data. Live LTE downlink (DL)
signal is captured using modeled LTE UE using software defined radio (SDR). The
detection analysis and classification performance shows promising results and
ascertains that, LTE-CommSense is capable of detection and classification of
different types of vehicles in outdoor road environment.
