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Research On Index Modulation-Based Grant-Free Non-Orthogonal Multiple Access

Posted on:2023-10-30Degree:DoctorType:Dissertation
Country:ChinaCandidate:J NiFull Text:PDF
GTID:1528306917979619Subject:Communication and Information System
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With the development of wireless communication technology and the promotion of social development demand,the Internet of Things has shown great potentials and market prospects.Massive machine type communication(m MTC),as an important application scenario in 5G,has the characteristics of huge equipment carrying capacity,short packet size of uplink data traffic,sporadic traffic pattern,low cost and low power consumption,which bring unprecedented challenge to random access mechanism in mobile communication system.Massive devices not only lead to the shortage of transmission resources,but also cause serious random-access collision,which further results in the waste of data transmission resource.In order to solve the challenge of random-access in m MTC,the index modulation(IM)based grant free(GF)non-orthogonal multiple access(NOMA)transmission is studied in this dissertation.Specific contents of this thesis are described as follows.To solve the problem of low transmission rate in existing non-coherent transmission schemes,the higher-rate IM-GF-NOMA transmission scheme and multiuser detection(MUD)algorithm are studied.Firstly,the non-coherent IM-GF-NOMA transmission scheme is proposed where each user activates multiple spread sequences simultaneously.And two MUD algorithms,the covariance based-Maximum Likelihood detection(CB-MLD)algorithm and the approximate message passing(AMP)algorithm integrated with IM structured sparse signal feature are derived in order to implement joint user activity detection(UAD)and data detection(DD).Secondly,an enhanced IM aided coherent GF-NOMA scheme is proposed,and the information is transmitted by both indexes of the active spread sequences and the constellation symbols.And the corresponding hybrid AMP is derived for UAD,channel estimation,and DD.Computer simulation shows that the proposed schemes can effectively increase the transmission rate.In order to improve the performance of MUD,the joint time-slot and spread sequence IM aided non-coherent GF-NOMA transmission is proposed.In this scheme,the transmission frame is divided into multiple channel time slots and multiple spread sequences are allocated to each user.The transmission information is carried by IM principle which applied in both channel time slots and spread sequences.At receiver,the non-Bayesian CB-MLD algorithm with adaptive threshold is proposed to perform joint UAD-DD.Computer simulation results show that the proposed scheme can effectively increase the sparsity of the estimated signal due to the IM in both time slot and spread sequence,and thus improve the MUD performance.Moreover,the proposed scheme is also suitable for block fading channels.In order to reduce the energy consumption of low-power m MTC devices,coherent and noncoherent GF-NOMA transmission schemes based on single-carrier(SC)modulation are proposed for frequency selected fading channels.Firstly,the signal models of coherent and IMbased non-coherent SC-GF-NOMA transmission schemes are derived.Based on the block sparsity of coherent SC-GF-NOMA and the hierarchical block sparsity of IM-based noncoherent SC-GF-NOMA,the block CB-MLD algorithm with signal subblocks as updating units is proposed.Moreover,for coherent SC-GF-NOMA,the Turbo AMP algorithm is also proposed,and the performance of Turbo AMP is analyzed by state-evolution formalism.Simulation results demonstrate the effectiveness of the proposed scheme.For IM-based slotted un-sourced random access(URA)in the dynamic user activity scenario,the multi-codebook-aided URA transmission scheme is proposed and a modified tree decoding implementation is presented.The effectiveness of the proposed scheme is verified by computer simulation.
Keywords/Search Tags:massive machine-type communication, grant free random access, index modulation, non-coherent transmission, multiuser detection
PDF Full Text Request
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