Aerospace and Electronic Systems Magazine July 2018 - 46

Feature Article:

DOI. No. 10.1109/MAES.2017.180054

LTE CommSense for Object Detection in Indoor
Environments
Santu Sardar, ANURAG, Defence Research & Development Organization, Hyderabad,
India
Amit K. Mishra, University of Cape Town, Cape Town, South Africa
Mohammed Zafar Ali Khan, IIT Hyderabad, Hyderabad, India

INTRODUCTION
In this work, we describe a new method of using long-term evolution (LTE) telecommunication infrastructure to sense environmental changes. We call it LTE communication-based sensing (CommSense). It can be used in various environment-sensing tasks, e.g.,
sea level monitoring, security of large unmanned landscapes, snow
avalanche monitoring, and activity detection inside forests. The
main concept of this technology is to focus on the known signal
embedded in the data frames. It compares the received signal with
the expected reference signal to estimate the change in the environment. LTE telecommunication infrastructure is used for this
environment-sensing task because of its wide coverage. In addition,
LTE uses a two-dimensional (2D) frame structure of orthogonal
frequency division multiplexing (OFDM) and multiple input and
multiple output (MIMO), which may yield better performance
compared to previous communication standards. This procedure of
extracting channel characteristics using commensal radar principles
does not affect the existing telecommunication system, because it is
a receive-only system. After the channel characteristics are estimated, they can be used to obtain phenomenological knowledge of the
environment using an application-specific instrumentation (ASIN)
framework. The capability analysis of this scheme is presented in
this article, first in simulation and then using field-collected data
captured with the help of a software-defined radio (SDR) platform.
The first known work in the open literature using radar for
data communication is the U.S. patent by Rittenbach published
in 1969 [1]. The field of coexisting telecommunication and radar
Authors' current addresses: S. Sardar, ANURAG, DRDO, PO
Kanchanbagh, Hyderabad, PIN-500058, Telangana, India,
E-mail: (sardar.santu@gmail.com). A. K. Mishra, Department of Electrical Engineering, Room 7.07, 7th Floor, Menzies
Building, Library Road, Upper Campus, University of Cape
Town, Cape Town, South Africa. M. Z. A. Khan, Department
of Electrical Engineering, IIT Hyderabad, Sangareddy, Kandi,
PIN-502285, Telangana, India.
Manuscript received February 15, 2017, revised May 8, 2017,
and ready for publication July 12, 2017.
Refereeing of this contribution was handled by D. O'Hagan.
0885/8985/18/$26.00 © 2018 IEEE
46

systems to detect and track targets has been gaining importance.
In general, the telecommunication and radar systems share benefits without a detrimental effect between them. This field is commonly known as passive radar or commensal radar [2]-[5].1 These
efforts of coexistence continue for various applications [5], [6].
One interesting way of exploiting the existing telecommunication system is to gather information from the channel estimation
blocks in the system. Channel estimation is performed to estimate
the effect of a dynamic channel on the unknown data pattern by
observing its effect on a known data pattern (reference symbols
or pilots). That means the output of a channel estimation block
contains channel information. Collectively, the channel properties
(scattering, fading, and power decay with distance) of the communication link are known as channel state information (CSI). This
CSI is exploited by our proposed CommSense scheme [7], [8]. In
the last 2 years, a large amount of work has been done regarding the feasibility of a global system for mobile communications
(GSM)-based CommSense system [4].
Our work on developing an LTE-based CommSense system
is presented in this article. It has a different set of challenges,
possibilities, and applicabilities compared to the corresponding
GSM-based system. In this article, we present initial results and
analysis of simulation data, as well as practical data captured using
an SDR-based LTE CommSense system. Application of the LTE
communication standard for communication-based environment
sensing is a novel idea. In LTE, the receiver user equipment (UE)
is significantly different from GSM-based UE. The motivations for
using LTE for CommSense are as follows:
C

The existing LTE network is widespread and will grow wider in the near future.
Because OFDM is basically wideband in nature, it is considered a waveform with low interception probability.
The wideband nature of OFDM has the ability to overcome
fading and multipath problems [9].
Using the property of frequency diversity, LTE CommSense
may provide more information about the scene of interest.

The word commensal is borrowed from ecology.

IEEE A&E SYSTEMS MAGAZINE

JULY 2018

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