Detection with target-incurring orthogonal subspace interference

In this paper, we consider the detection of a deterministic signal with an unknown scaling amplitude in the presence of a colored noise, when there is a covariance mismatch between the null and alternative hypotheses. Specifically, we consider a scenario where the target incurs an additional subspace interference that is orthogonal to the target steering vector and only present under the alternative hypothesis. To address this problem, we apply the generalized likelihood ratio test (GLRT) principle which results in a detector involving the following steps: the observation is first projected into the interference subspace. Then, the energy of the projected signal (residue) is computed. If the residual energy is small, the GLRT reduces to the standard matched filter (MF) which ignores the subspace interference; otherwise, a modified test statistic is employed for additional interference cancellation. Simulation results are presented to demonstrate the effectiveness of the proposed detector.