OPTIMAL PN SEQUENCE DESIGN FOR QUASISYNCHRONOUS CDMA COMMUNICATION-SYSTEMS

In this paper, the conventional quasisynchronous (QS) direct sequence (DS) code-division multiple-access (CDMA) communication system is gene ralized, and the problem of optimal spreading pseudonoise (PN) sequenc e design for new QS DS-CDMA communication systems is formulated, The c lasses of optimal PN sequences which have good pseudo-randomness and v ery small cross-correlation values for some range of offsets are desig ned by using a matrix-based approach, In contrast to the case of the o ther sequences, optimal PN sequences in this paper produce small multi ple-access interference (MAI) which is not affected by the number of u sers if there are sufficiently large number of users in the link, The new results are compared with the commonly used PN sequences to prove the superiority of our designed sequences, and the system performances of the QS-CDMA systems using different PN sequences are also evaluate d.