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Two-Level FH-CDMA Wireless Communication Systems Using Quadratic Congruence Codes

In this paper, a two-level frequency-hopping code-division multiple-access (FH-CDMA) scheme, which is flexible in the selection of modulation codes and FH patterns, is studied. This two-level FH-CDMA scheme can be modified by the partition of the modulation codes in order to support more subscribers without increasing the number of FH patterns. The performance and spectral efficiency (SE) analyses show that our scheme supports higher data rate and SE than Goodman's frequency-shift-keying FH-CDMA scheme, making the former more attractive for wireless communication systems.