“…. Sampling the above sequences at symbol period would produce a matrix C in (1.47) with imperfectly known entries unless {τ k , ω l , θ k } are precisely known for all k. Different timing and frequency recovery techniques have been tested specifically for multibeam return links using MUD [67]; the latter reference proposed a hybrid algorithm, where a nondata aided estimate is refined by exploiting the pilot pattern, and concluded that good performance results can be obtained if the start of the frames can be correctly decoded, even though better pilot sequences would probably be required. c kL ), we have that c k (t) = L n=1 c kn g(t − nT), k = 1, .…”