Studies on interference mitigation schemes in mc ds cdma systems

Abstract

The Multi-Carrier Direct-Sequence Code Division Multiple Access newline(MC DS CDMA) transmission technologies deliver broadband (BB) wireless newlinecommunication (WC) services and they work as an unprecedented system to newlineaccess large users with high speed secured wireless communications. newlineMulticarrier modulations have been supported by numerous wireless newlinemultimedia transmission standards, for example, digital video broadcasting newlineand digital audio broadcasting, because they have a higher level of immunity newlinefor multipath fading and noise. MC DS CDMA is a multicarrier modulation; newlineit is regarded to be a suitable method for the downlink of cellular systems. newlineThe performances of a MC DS CDMA system will be affected by the newlineinterferences that influence the system. The interferences are a) Multi-Path newlineInterference (MPI) caused due to multipath delays and b) Multiple Access newlineInterference (MAI) caused by multiple access delays. Both the interferences newlinelead to self-interference and Multi-user Interference (MUI) that reduces the newlinecapacity of MC DS CDMA systems.In the proposed work, various approaches are presented and they newlineare given below. The initial approach deals with a Transmitter based linear newlinepre-coding design that gives out a better performance on considering the newlineconventional pre-coding by utilizing the known interferences between the newlineusers of MC DS CDMA downlink system. The interferences are utilized by newlineselectively orthogonalizing the preferred symbols to Destructive Interference newline(DI) by pre-coding while permitting constructive interference for the required newlinesignals in transmission.The productive interferences spread the signals collected and newlineincrease the Signal-to-interference plus noise ratio (SINR) at the receiver. The newlineintroduced first scheme is applied to the downlink of cellular newline newline