Semi-blind closed-form co-channel signals separation method used in smart antenna systems

In this paper, a semi-blind closed-form co-channel signal separation method is proposed, which is based on two steps. The first is to estimate the zero space of multi-user signals. The second is to estimate them using LMS method and some short sequence, which is always known in digital communication systems. Compared with non-blind signals, the new method needs very short sequence, the shortest length of which is equal to the number of co-channel users. At the same time it can overcome the shortcoming of blind signals in computational complexity and lack of global convergence. Computer simulation demonstrates that the new method is suitable for cochannel signal separation in smart antenna system when multipath exists.