A class of multi-valued signature sequences for DS/CDMA systems

In this paper, we propose a class of multi-valued signature sequences for direct sequence code division multiple access (DS/CDMA) systems. We obtain the signature sequences by modifying the coefficients of the subbands of a perfect reconstruction quadrature mirror filter (PR-QMF) bank. The class has perfect correlation properties for synchronous DS/CDMA systems, and in general has better correlation properties than other well-known sequences in asynchronous DS/CDMA systems also. Some numerical results for the performance of the asynchronous DS/CDMA systems with several sequences including the proposed class of sequences are obtained.