Constrained Contextual Bandit Learning for Adaptive Radar Waveform Selection

TL;DR

This paper introduces a linear contextual bandit approach for adaptive radar waveform selection, leveraging spectrum sensing and feedback to improve target detection in various environments, including adversarial scenarios.

Contribution

It formulates the waveform selection as a linear contextual bandit problem, enabling computationally feasible and sample-efficient adaptive radar strategies.

Findings

Significant performance improvements in target detection with bandit algorithms.

Effective handling of adversarial environments with stochastic and adversarial models.

Mitigation of pulse-agile impacts through time-varying waveform constraints.

Abstract

A sequential decision process in which an adaptive radar system repeatedly interacts with a finite-state target channel is studied. The radar is capable of passively sensing the spectrum at regular intervals, which provides side information for the waveform selection process. The radar transmitter uses the sequence of spectrum observations as well as feedback from a collocated receiver to select waveforms which accurately estimate target parameters. It is shown that the waveform selection problem can be effectively addressed using a linear contextual bandit formulation in a manner that is both computationally feasible and sample efficient. Stochastic and adversarial linear contextual bandit models are introduced, allowing the radar to achieve effective performance in broad classes of physical environments. Simulations in a radar-communication coexistence scenario, as well as in an adversarial radar-jammer scenario, demonstrate that the proposed formulation provides a substantial improvement in target detection performance when Thompson Sampling and EXP3 algorithms are used to drive the waveform selection process. Further, it is shown that the harmful impacts of pulse-agile behavior on coherently processed radar data can be mitigated by adopting a time-varying constraint on the radar's waveform catalog.