Opportunistic Sensing Using mmWave Communication Signals: A Subspace Approach

Subspace-Based Detection and Localization in Distributed MIMO Radars

“…In this study, we consider the JDL of multiple targets in a distributed MIMO radar with an imperfect waveform separation. Interestingly, a somehow similar problem has been recently considered in the context of mmWave dualfunction radar-communication systems [18]- [21] and of passive radars [22], [23]. Inspired by these related studies, we make the following contributions.…”

“…To proceed, notice that r p is the noisy superposition of an unknown number of subspace signals originated from as many targets; the k-th subspace signal belongs to the column span of the mode matrix S p (x k ), which only depends upon the target location x k . Leveraging the design methodology in [21], we propose to solve a sequence of composite binary hypothesis testing problems: in each problem, we aim to detect a subspace signal generated by a prospective target with an unknown location in the presence of the subspace interference caused by the previously-detected targets plus independent noise.…”

“…We show that the superposition of the echoes produced by each target in response to waveforms emitted by the radar transmitters can be regarded as a subspace signal, whose structure is specified by the target location. Following the design methodology in [21], we derive a novel iterative subspace-based detector that extracts one target at the time from the data and is robust to the sidelobe masking caused by the stronger targets on weaker ones. The proposed procedure generalizes the one discussed in [21] to the case where multiple widely-spaced transmitters/receivers are present and the targets belong to linear subspaces which may be not independent.…”

“…Following the design methodology in [21], we derive a novel iterative subspace-based detector that extracts one target at the time from the data and is robust to the sidelobe masking caused by the stronger targets on weaker ones. The proposed procedure generalizes the one discussed in [21] to the case where multiple widely-spaced transmitters/receivers are present and the targets belong to linear subspaces which may be not independent. Finally, we assess the performance of the proposed detector, also in comparison with the solution in [11] and the single-target benchmark.…”

Radar-enabled ambient backscatter communication

“…A far less costly strategy relies on the exploitation of signals of opportunity-typically, the signal emitted by TV/FM towers, cellular base stations, and Wi-Fi access points-to implement a passive radar, which has the merit of being low-cost, difficult to jam, easy to deploy, and undetectable [7]. To the family of passive radars can be somehow ascribed the opportunistic architectures considered in [8]- [11], mainly with reference to automotive applications through millimeter-wave (mmWave) communication signals: in close proximity with the communication transmitter, a radar receive chain, which may avail itself of information shared by the transmitter, implements the sensing function without producing interference and without requiring any additional physical resource. In particular, [12] puts forward mmWave communication signals as the only credible means to support massive automotive sensing.…”