Binary signal design for approximately synchronized CDMA systems without detection sidelobe nor co-channel interference using auto- and cross-complementary codes
N. Suehiro, Noriyoshi Kuroyanagi · 2002
For mobile cellular CDMA systems, co-channel interference in the uplink is the most serious problem, because the power control or the interference cancellation required increase the system's cost. From this view point, Suehiro (1993, 1994) proposed a method for signal design by applying the pseudo-periodic sequences concept on the periodic sequence set without cross-correlation. Using this method, we can design CDMA signals without co-channel interference when the system is approximately synchronized. Approximate synchronization is not difficult for uplink in cellular mobile systems, so this signal design method is useful. Another problem of multipath fading is also solved by the proposed method, because the filter output has no sidelobe in the small shift terms. A signal design method is proposed by using a complete complementary code. Using the proposed method, we can design binary CDMA signals for far wider shifts of without sidelobe nor co-channel interference. In fact, the length of shifts without the influence of multipath is 2/sup n/ for any n.