Research On Waveform And Multiple Access Technologies In Machine Type Of Communication

With the rapid development of wireless communication networks and the explosive growth of different terminal equipment,the machine type communication scenario has become an important scenario of 5G communication with large number of connections,small data packets and sporadic transmission.Due to the characteristics of the machine type communication scenario,the traditional orthogonal waveform technologies and multiple access technologies can't meet the demand of higher spectral efficiency and massive device connections.According to the challenges posed by this scenario,it is urgent to study new non-orthogonal waveform technologies and multiple access technologies.The main contents of this thesis include:First of all,different waveforms' performances were analyzed in machine type communication scenario.Due to OFDM's large out-of-band emission,sensitivity to time frequency offset and higher peak-to-peak power,it is not suit to this scenario any more.In this paper,the emphasis of waveform research was on non-orthogonal waveform technology.Three candidate waveforms,i.e.,orthogonal frequency division multiplexing(OFDM),filtered orthogonal frequency division multiplexing(F-OFDM)and universal filtered multi-carrier were evaluated in link level simulation platform.Their performances of BLER and PSD were compared and then the suitability of the non-orthogonal waveforms was proved in MTC.Secondly,different non-orthogonal multiple access schemes were evaluated.In traditional orthogonal multiple access scheme,an orthogonal resource can only be allocated to one user,so it is difficult to meet the demand of mass connection in the machine communication scenario.Non-orthogonal multiple access can not only control the interference reasonably but also meet the requirements of large-scale connection through appropriate non-orthogonal resource allocation.In this paper,three kinds of non-orthogonal multi-access technologies were evaluated which are discussed more extensively in 3GPP,i.e.,interleave division multiple access(IDMA),sparse code multiple access(SCMA)and non-orthogonal code access(NOCA)with a comprehensive horizontal analysis and comparison.The different block error rate performances of different non-orthogonal multiple access schemes under different channels and coding rates were obtained,which provided a reference for the standardization of 5G multiple access technologies.Thirdly,a power domain non-orthogonal multiple access scheme based on tandem spreading was proposed,which includes the design of the transmitter codebook and the design of the receiver algorithm.Compared with the traditional power domain multiple access scheme based on spreading,this scheme achieves the improvement of the error block rate performance when the system users are overloaded.In addition,it also has the blind user identification function that the traditional scheme does not have,that is,without knowing the prior information such as the codebook and the pilot of the activated user,the identification of the active user can be realized only based on the received information.It can not only save the signaling overhead in the scenario of machine type communication but also has a low complexity of implementation.The research results of this paper have certain theoretical significance and practical value for the design of 5G machine type communication system.