Research On Application Of EMD-ICA Algorithm In OFDM Communication System

Orthogonal Frequency Division Multiplexing is essentially a scheme of multiplex multicarrier.As a type of efficient wireless transmission technology,OFDM has been adopted by many wireless communication systems because of its strong anti-interference performance and high spectrum efficiency.To begin with,the paper proposes a new method of applying Empirical Mode Decomposition algorithm to realizing frequency offset estimation of single channel OFDM system.Then for solving the modal aliasing problem aroused from EMD separation,EMD-ICA integrated algorithm is further carried out on the research of OFDM communication system by jointing Independent Component Analysis method to eliminate modal aliasing phenomenon.Satisfyingly,the CFO estimation scheme which based on EMD-ICA algorithm is achieved ultimately.The research work of this thesis mainly includes the following contents:Firstly,the paper gives the background and significance of the study,and elaborating the basic models and the modulation-demodulation process of OFDM system.Meanwhile,illustrating its advantages and disadvantages.What's more,the article combs the latest research status of the frequency offset estimation of OFDM system and EMD-ICA integrated algorithm earnestly through a plenty variety of literature.Secondly,the chapter elicits the root of OFDM synchronization error according to the consequence of the wireless channel fading characteristics and doppler frequency shift.In view of the problem where synchronous deviation degrades OFDM system performance aroused from carrier frequency offset,the paper puts forward OFDM system research plan based on EMD and ICA integrated technique on the premise of comparing with traditional CFO estimation algorithms meticulously.In addition,the segment introduces time-frequency analysis and EMD modeling method.simultaneously,it also concludes a method of eliminating EMD aliasing effect by proposing the principle of Hilbert transformation and the main features in EMD algorithm.Subsequently,the paper demonstrates a original method of EMD algorithm applied to OFDM system frequency offset estimation in accordance with single channel OFDM model of the relative detection.Comparing with the traditional CFO estimation,the simulation shows that the project can improve spectrum efficiency on one hand,and on the other hand,it makes contribution to reducing the difficulty of the implementation on the system,more importantly,it does not need any additionaltraining sequence.Eventually,depending on the novel viewpoint that ICA technique can eliminate the modal aliasing,the paper explores a conception of achieving CFO estimation in OFDM system by virtue of the EMD-ICA algorithm.Here the paper not only improves the problem of CFO estimation performance,which decreased together with the increasing of multicarrier number resulted from mode mixing interference,but also further enhances the CFO estimation precision.Besides,through multiple simulation performance evaluation,the confluent algorithm is verified effectively and feasibly at last,which offering a new perspective of OFDM synchronization technology's realization and having a certain practical value at the same time.