Multi-domain collaborative filter for interference suppressing

Filters with antenna arrays are widely used for interference suppression in the temporal domain, frequency domain, space domain and so on. Meanwhile, the interference mitigation performance of a single-domain-based filter depends on a noticeable difference between the target signal and interference in the corresponding domain. However, the interference cannot be efficiently suppressed by a single-domain-based filter when the difference in this individual domain is small. To solve this problem, a multi-domain collaborative oblique projection filter is proposed in this study. First, multi-domain spaces are theoretically derived to distinguish the target signal and the interference, and then a multi-domain oblique projection operator is provided to recover the original target and suppress the interference. Depending on the multi-domain spaces, the filter has excellent performance when the difference is insignificant in each individual domain, whereas the performances of the single-domain-based filter and cascade filter degrade significantly. Finally, a space-polarisation-frequency domain collaborative filter based on oblique projection is given as an illustration. Performance analysis and simulation results are provided to illustrate the superiority of the proposed filter for interference mitigation.