A Study On Detection Algorithm Of MIMO-GFDM System For The Fifth Generation Communication

The fifth generation mobile communication poses higher challenges to wireless communication system,such as providing higher transmission rate,achieving lower time delay and providing flexible waveform selection.Orthogonal Frequency Division Multiplexing(OFDM),which is widely used nowadays,cannot meet these requirements.Therefore,suitable alternatives need to be found.Generalized frequency division multiplexing(GFDM)has attracted much attention because of its flexibility and robustness.Multi-input multi-output(MIMO)is an essential technology for any candidate waveform.Compared with OFDM,GFDM is comparable accuracy in MIMO detection,but its detection complexity is much higher,which is not conducive to hardware implementation.In addition,when subcarrier non-orthogonal GFDM waveform is used in MIMO channel,it is subject to triple Interference from inter-carrier Interference(ICI),inter-symbol Interference(ISI)and inter-antenna Interference(IAI),and it is necessary to eliminate interference through equalization at the receiving.This also leads to the high computational complexity of GFDM detection and equalization algorithm,which greatly limits its use in practical projects.Therefore,it is of great significance to design a low complexity and high performance MIMO-GFDM detection algorithm.Based on the traditional detection algorithm iteration minimum mean square error(MMSE)with parallel interference cancellation(PIC),a novel MMSE-PIC detection scheme is introduced for MIMO-GFDM.By using conditional unbiased estimator instead of traditional biased estimator,the proposed eliminates the bias in the detection process.The correlation between frequency-domain data estimation and time-domain data estimation is analyzed at the algorithm level.Based on this,a three-step MMSEPIC demapping is introduced.In order to reduce the computational complexity sufficiently without loss of performance,the estimator is decomposed into multiple subsystems by using the special properties of the matrix in the three-step formula,and a low-complexity approximate solution combined factorized system matrix and conjugate gradient method is introduced.The complexity evaluation shows that compared with the original iterative MMSE-PIC detector with a cubic order of computation complexity in terms of subsymbol numbers M,the three-step iterative detection has only a quasi-linear order,which is approximately as linear as OFDM.The comparative experiment of frame error rate(FER)between GFDM and OFDM under different iteration times shows the fact that iterative receiver is superior to non-iterative receiver and GFDM is superior to OFDM.In addition,the comparison experiment of maximum likelihood performance shows that the proposed iterative MMSE-PIC detection algorithm can achieve the optimal maximum likelihood detection performance.