  Facilitating the coexistence of radar systems with communication systems has
been a major area of research in radar engineering. The current work presents a
new way to sense the environment using the channel equalization block of
existing communication systems. We have named this system CommSense. In the
current paper we demonstrate the feasibility of the system using Global System
for Mobile Communications (GSM) signals. The implementation has been done using
open-source Software Defined Radio (SDR) environment. In the preliminary
results obtained in our work we show that it is possible to distinguish
environmental changes using the proposed system. The major advantage of the
system is that it is inexpensive as channel estimation is an inherent block in
any communication system and hence the added cost to make it work as an
environment sensor is minimal. The major challenge, on which we are continuing
our work, is how to characterize the features in the environmental changes.
This is an acute challenge given the fact that the bandwidth available is
narrow and the system is inherently a forward looking radar. However the
initial results, as shown in this paper, are encouraging and we intend to use
an application specific instrumentation (ASIN) scheme to distinguish the
environmental changes.
