Transmitter Subspace-Aware Target Detection in Two-Channel Passive Radars with Inter-Receiver Collaboration

We address target detection in a single Delay-Doppler cell using spatially distributed two-channel passive radars. An unknown illuminator of opportunity (IO) is assumed to emit a waveform lying in a known low-dimensional subspace (e.g., OFDM). Each receiver transforms its reference and surveillance signals onto the IO subspace after noise-whitening, to obtain cross-correlation (CC) measurements. To save bandwidth, receivers collaboratively exchange and linearly combine the CC output, and only a subset transmits them to a fusion center (FC) over a multiple-access channel (MAC). Collaboration weights are designed using the moments of the FC measurement to enhance detection performance.