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Research Of New Multiple Access Cooperative Communication Technology

Posted on:2020-03-27Degree:MasterType:Thesis
Country:ChinaCandidate:J J MeiFull Text:PDF
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As a key technology to solve the problem of channel connection between wireless communication users,multiple access technology also reflects the evolution of the wireless systems.From the earliest 1st-generation(1G)wireless systems to the currently widely used 4th-generation(4G)wireless systems,these systems are based on frequency division multiple access(FDMA),time division multiple access(TDMA),code division multiple access(CDMA)and orthogonal frequency division multiple access(OFDMA)technology,respectively.For the development and deployment of the 5th-generation(5G)wireless systems,the conventional multiple access technology is difficult to satisfy the requirements of ultra-high data rate,low latency,high reliability and large-scale connection.The proposals and researches of new multiple access technology has also become a focus.As a wireless communication technology widely deployed in existing wireless communication systems,cooperative communication technology is an important solution to combat channel fading,which can effectively increase communication coverage and improve system performance.In order to take advantage of the cooperative communication technology,the combination of new multiple access technology and cooperative communication technology has become a hot research topic for 5G wireless systems.Therefore,this paper carries out the research on the combination of new multiple access technology and cooperative communication technology(i.e.,non-orthogonal multiple access cooperative communication technology),including:First,a single carrier non-orthogonal multiple access(NOMA)cooperative system in multi-relay scenarios is studied.A relay selection strategy based on the optimal performance of the system outage probability is proposed,whose diversity gain is equal to the number of relays.The closed-form expression of the system outage probability under the relay selection strategy is derived and simulated.Based on the system outage probability closed-form expression,the optimal solution of the power allocation factor between users is derived.Second,the multi-carrier diversity NOMA cooperative system in the cellular scenario is studied.Aiming at the characteristics of large-scale fading and poor channel conditions of cell-edge users,a multi-carrier diversity NOMA cooperative scheme based on full-duplex relay cooperative service is proposed to improve the reliability of cell edge users.When the channel state information is not available at the transmitter,the closed-form expression of the system outage probability using the selective combining(SC)scheme at the receiver is derived.When the channel state information is available at transmitter,the successive interference cancellation(SIC)decode sequence based on the channel transient state information is proposed.This avoids additional outage from SIC decoding in the downlink NOMA system,which greatly improves the system outage performance.Moreover,the system outage probability under the maximum ratio combining(MRC)scheme at the receiver is discussed.Compared to the SC scheme,the outage performance of MRC can be effectively improved.Thirdly,the multi-carrier multiplexed NOMA cooperative system in the ultra-dense relay and user nodes scenario is studied.For the ultra-dense access points and multi-user nodes scenario in some 5G scenarios,a user-centric multi-carrier multiplexing NOMA cooperative scheme is proposed to improve system throughput.The system resource allocation optimization problem that satisfies the target requirements of each user is constructed.A dynamic grouping matching algorithm for multiple relays and users,and an iterative algorithm that joint power and carrier allocation based on convex function difference programming are proposed to optimize system resource allocation and thereby improve system throughput.The thesis provides theoretical and methodological support for the effective combination of new multiple access and cooperative communication technology.The effectiveness of the schemes is verified by simulation.These schemes have theoretical and application value and can be deployed in 5G scenarios.
Keywords/Search Tags:multiple access, cooperative communication, the fifth-generation wireless systems (5G), non-orthogonal multiple access (NOMA)
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