The Suppression Algorithm Of GSM Interference In WCDMA System

As the mobile communications developed rapidly,3G systems bring us more business，increasing data rate, while it also has made the spectrum resources tense increasingly. TheWCDMA system and the GSM system will interrupt each other while the co-frequencytransmission occurs. This interference in the transmitting process can be shown as anarrow-band interference, which would significantly affect the sending of the signal in theWCDMA system if no optimization. So how to suppress the co-frequency transmissioninterference becomes the key point.The narrowband interference suppression technology is divided into time domainprediction technology, transform domain filtering technology and code-aided technology. Thecode-aided technology is a novel method that has the advantage of suppressing the low ratenumeric narrowband interference, which also can suppress the MAI and NBI. Consequently,here the paper achieves WCDMA interference-suppression via code-aided technology.Firstly, According to the observation of the simulation in a GSM&WCDMAco-frequency transmission system, the narrow-band interference leads to a distortionsimulation result to WCDMA system, in which should be reduced.From the next part of the paper, we can see that a WCDMA system based on the MMSEand ZF code-aided algorithm model are simulated separately and compared to each other. Thealgorithms are modeled and their performance of GSM suppressing are also tested.Draw thebelow conclusion via the simulations results analysis, the MMSE shows better performance toZF in co-frequency interference suppression, but worse than ZF in MAI suppression.Finally, Faced with the fact of that the WCDMA system is the multi-rate CDMA systems,this paper proposes code-aided suppression technology for multi-rate system. The Systemsimulation results show that this suppression technology has a good performance in the GSMco-frequency interference suppressing.The research results on the interference suppression can be applied in the existingcommunication systems and future communication when they are co-exist, which has greattheoretical importance and economic value.