Research On Turbo Frequency Domain Equalization Technology In GSM System

GSM communication system has become the most sophisticated mobile communications standard through a long-term development. In order to satisfying the people's higher demands to mobile communications, which has to absorb a variety of advanced technologies to achieve continuous improvement. Turbo equalization gets great attention due to the handle method of combining data equalization and decoder. In addition, in the 4G communications standards, single-carrier frequency domain equalization technology obtains a wide range of applications for its lower complexity,simple realization and resisting high PAPR.The two kinds of advanced technology was integrated into the GSM communication system in order to obtaining a better system performance solution, simulation results show that our exploration gets a great success.The main results of this thesis are as follows:1. The traditional turbo equalization principle and the turbo receiver frame was described, a detailed theoretical analysis and performance simulation on the iterative MAP receiving algorithm with the best performance was done.2. The basic frequency-domain equalizer (ZF and MMSE) performance was Compared, the low-complexity linear MMSE equalizer was studied based on it and also the performance simulation was showed.3. The soft interference cancellation frequency-domain equalizer and its optimized algorithm was studied. The GSM system is simulated, it showed that the symbol-wise soft interference cancellation frequency domain equalizer combined the Turbo technology having obtained the outstanding performance.4. The frequency-domain soft-feedback equalizer was studied in detail, it has an advantage of "soft information", "decoding feedback" and so on, whose performance is better than the iterative MAP algorithm and it achieves a great gain. So that it becomes an excellent solution of the turbo frequency-domain equalization in GSM.5. The MMSE-RISIC iterative receiver algorithm was proposed.Firstly the inter-symbol interference generated by data in the frequency domain was estimated as a whole and then be canceled, after MMSE filtering it generates a new output, eventually sent it to the decoder iteration. Simulation results show that iterative algorithm gets 0.728dB performance gain, only 0.3dB performance difference compared to the MAP algorithm, which is a approximate optimal performance solution.6. The turbo receiver performance scheme was proposed with compatible to the GSM system which is carried out easily. Simulation results show that soft-interference frequency-domain cancellation equalizer, MMSE-RISIC,FDE-FDDF-Soft are the excellent performance solution, in which the FDE-FDDF-Soft is the best solution for GSM Turbo receiver system performance.