Low-Hit-Zone Frequency/Time Hopping Sequence Sets With Large Family Size

For a quasi-synchronous frequency/time hopping (FH/TH) code-division multiple-access (CDMA) system which involves many users, the low-hit-zone (LHZ) FH/TH sequence set with large family size is necessary. In this paper, an upper bound on the family size of LHZ FH/TH sequence sets is derived. The new bound includes the Singleton bound on FH sequence sets as a special case. Further, three constructions of LHZ FH/TH sequence sets are presented, which have optimal/near optimal family size and also optimal maximum Hamming correlation (MHC) with respect to the new bound. They have very large family size compared with the known LHZ FH/TH sequence sets in the literature.