Research On The Detection Of SEFDM Non-orthogonal Transmission Signal

Now,with the increasing demand of communication,the limited spectrum resource is challenged and improving the spectrum efficiency has been a problem to be solved.For traditional orthogonal transmission technologies(e.g.OFDM),adopting higher order modulation is the only way to improve the spectrum efficiency.However,This will make the system very sensitive to noise and the performance of the system will degrade.Therefore,Non-orthogonal transmission technology with high spectral efficiency has gradually been in a hot research at home and abroad.As a kind of Non-orthogonal transmission technology,Spectrally Efficient Frequency Division Multiplexing(SEFDM)technology can transmit more information in the same bandwidth by compressing the distance between subcarriers of OFDM signals.Thus,SEFDM can improve the spectrum efficiency.However,the non orthogonality between subcarriers brings serious inter-carrier interference(ICI),which cause the detection algorithm of traditional OFDM orthogonal signals no longer applicable.Therefore,this thesis mainly studies the detection algorithm of SEFDM signals.This thesis first studies the basic theory and basic principle of SEFDM Technology.On the basis of this,the basic model of SEFDM system is introduced,and this thesis explains the SEFDM system has the characteristics of high spectrum efficiency compared with OFDM system.In addition,IFr FT-based and IDFT-based signal generation schemes are introduced which lay the foundation for the introduction of detection algorithms of SEFDM signals.Then,this thesis proposes a kind of QRM-MLD-based detection algorithm of SEFDM signals by comparing SEFDM system with MIMO system.The QRM-MLD-based detection algorithm reduces the computational complexity of ML algorithm at the expense of performance of the system.On the basis of this,an improved scheme is proposed and it can reduce the computational complexity of the algorithm more.Finally,aiming at the problem that the detection performance of existing detection algorithm is not good enough,this thesis introduces a kind of detection algorithm of SEFDM signals combined with Turbo equalization.and on the basis of this,an improved scheme is studied which can reduce the computational complexity for calculating inter-carrier interference.