New quasi-orthogonal BCH-derived sequences for CDMA applications

European Transactions on Telecommunications, vol. 18Based on two methods recently proposed—the ‘Ranging Criterion’ (RC) and the ‘Generators Ranging Criterion’ (GRC)—new (quasi orthogonal) even BCH-derived sequences are generated which are very attractive for synchronous or quasi-synchronous Code Division Multiple-Access (CDMA) systems. Numerical results show that the new family of BCH-derived sequences can contain a higher number of quasi-orthogonal sequences with lower correlation values and higher processing gains (PGs) than the spreading sequences typically used in the third generation of mobile communications system, UMTS or in the recent large area synchronised CDMA (LAS-CDMA) technology. It is shown that the even BCHderived sequences are easily generated by a linear shift register generator, allowing the construction of systems with receiver structures of low complexity as compared with those of quasi-synchronous systems using low correlation zone sequences, as for instance the LAS-CDMA system

New Bch-Derived Sequences For Cdmasystems

New BCH-derived PN-EB (pseudo-noise even balanced) sequences suitable to be used in CDMA systems are presented in this paper. It is assumed a new definition for Processing Gain, which better accounts for the system performance regarding the narrow band noise rejection, and it is shown how to obtain high processing gain values, namely, by using zero mean spreading signals in channels with selective noise. The new sequences have low autocorrelation levels, exist in large numbers and can provide higher processing gain with selective noise