New quasi‐orthogonal BCH‐derived sequences for CDMA applications

Based 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 BCH‐derived 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. Copyright © 2007 John Wiley & Sons, Ltd.