"Stan Pawlukiewicz" <stanp@nospam_mitre.org> wrote in message news:btet0l$eid$1@newslocal.mitre.org...> Fred Marshall wrote: > > "Jeff" <freelait2000@yahoo.com> wrote in message > > news:6cdef69d.0401060604.4e1f9c70@posting.google.com... > > > >>Hi, > >>I want to simulate an adaptive beamforming algorithm (using QR-RLS). > >>From what I learned, I have the following thoughts and questions. > >>Because I am not sure whether they are right or not (and the question > >>is still unsolved), I want to get your answer to these. > >>From �Adaptive Filter Theory� of Simon Haykin, 4th edition, Page 115, > >>"The essence of a Wiener filter is that it minimizes the mean-square > >>value of an estimation error, defined as the difference between a > >>desired response and the actual filter out." The LS based algorithms > >>are optimized in the least square sense (?). QR-RLS is one of LS > >>algorithm, which has some adavantage in structure, accuracy, > >>convergent speed, etc.. > >>From some of the papers of QR-RLS I read, they are evaluated in a > >>situation of known direction of the desired signal and the > >>interferences. QR-RLS algorithm can adaptively suppress the > >>interference signals at the same time enforce the desired signals from > >>different antennas. The reference signal for the QR-RLS is the pilot > >>PN binary sequences, i.e., in the time domain. I want to do a similar > >>simulation with the desired and interference signals known their > >>directions (There are 4 antennas to receive these signals). My > >>question is: how can I design the signal source model with the > >>intended directions? I have been thinking for quite a while. Could you > >>help me? > > > > > > If you already know the directions then the problem is deterministic andyou> > can design an optimum array weighting to zero out the interferingsources -> > as long as there aren't too many of them. In this case, you appear tohave> > amplitude and phase that can be adjusted for each antenna, is thatright?> > I'd look for papers that adjust complex coefficients (i.e. amplitude and > > phase) to get optimum array patterns. > > > > The adaptive algorithms are good for situations where you don't know the > > direction of the interfering sources. > > But they suck if you don't know the directions of the desired signals.Good point Stan. That was an unstated assumption. I guess if the antenna array is always physically aimed (rotated) at the desired source always then this is a contraint on the main lobe as is often the case. Fred