Subspace coherence for detection in multiuser additive noise channels

The matched subspace coherence detector for signals in additive noise and subspace interference is presented. This detector rejects interference and it is invariant to various types of scaling and rotations that model incoherent channels. This makes it a logical choice for multiuser communication channels where one user is interfered with by other users. The detector is developed for multiuser M-ary signaling schemes in colored noise.