Spatial division multiple access with DOA based digital beamforming in mobile satellite communications

This paper proposes a new scheme for spatial division multiple access (SDMA) in mobile satellite communication by using DOA based digital multiple beam forming with uniform circular antenna array. The schem extends Weight Subspace Fitting algorithm to two dimensions so as to estimate the azimuth and elevation angles of the signals received at the satellite. With these angle estimates and using multiple digital beam forming technique, the signals arriving at the satellite can be well separated from one another and communication channels to the different users within different geographical areas can thus be provided to realize SDMA scheme. This technique can be used to complement existing FDMA, TDMA or CDMA schemes in current mobile satellite systems.