BLIND BEAMFORMING TECHNIQUES FOR AUTOMATIC IDENTIFICATION SYSTEM USING GSVD AND TRACKING

The automatic identification system (AIS) is a wireless synchronous narrowband communication system for exchanging navigational data through short messages between ships and base stations in the maritime VHF frequency band. The service coverage of each communication cell is limited within the horizon by the line of sight propagation of VHF signals. AIS receivers are put on high buildings besides harbors, lighthouses along coastlines and even on LEO satellites in space to detect signals from more cells. The toughest problem that these receivers are facing is the partial overlapping of messages from multiple cells. Antenna arrays are used in AIS receivers to suppress the interference. A good beamforming algorithm is needed for computing beamformers. Previously, we proposed blind beamforming techniques based on subspace intersection to solve this problem. In this paper, we propose more simple and efficient blind beamforming techniques using the generalized singular value decomposition (GSVD) and its tracking version for the same problem. The proposed algorithms are simulated in an exact dynamic AIS software model, and are tested on real-world AIS signals collected from our experimental hardware. Simulation results show that the proposed algorithms achieve satisfactory performance. Experimental results confirm the effectiveness of the proposed algorithms.