Sequence Design for Cognitive FH-CDMA Systems

Based on the concept of cognitive radio (CR) and the idea of no-hit zone (NHZ), a novel cognitive frequency hopping code division multiple access (FH-CDMA) system is proposed, and the related FH sequences with NHZ are designed. When sensing spectrum usage from primary users, the cognitive FH-CDMA system employing NHZ FH sequences can flexibly change hopping frequencies to avoid interference to primary users while the whole FH-CDMA network can continue to be kept orthogonal without multiple access interference (MAI).