Interference-free CDMA air-link technology promising noise-limited performance

This paper addresses the issues on design of innovative interference-free CDMA technologies whose performance is limited by noise only. Firstly, technical limitations associated with interference-limited properties of traditional CDMA systems are revisited. Next, it is demonstrated that it is possible to eliminate both multiple access interference (MAI) and multipath interference (MI) in a CDMA system using perfectly orthogonal complementary codes (CC). A novel CDMA system architecture, namely DS/CC-CDMA, with an inherent immunity against MAI and MI is proposed, enabling a truly noise-limited performance. The proposed scheme can offer an isotropic MAI-free and MI-free operation in both synchronous down-link and asynchronous up-link channels as well as a very low implementation complexity. The introduction of the DS/CC-CDMA architecture gives us a great hope for a substantial capacity increase for the next generation wireless applications, which ought to deliver a much higher transmission rate than possible today.