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Investigation Of Feedback And Precoding Technologies In Multi-antenna Systems

Posted on:2017-04-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:C WangFull Text:PDF
GTID:1108330482972510Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
In recent years, mobile internet is developing with an unprecedented speed into every cor-ner of our lives, with the goal of satisfying the demand of various applications, specially to break out the constraint of the scarcities of bandwidth and power on the further development of wire-less communication, multi-antenna technology is proposed to enhance transmission reliability, improve spectrum efficiency by exploiting its spatial degree of freedom. The feedback and pre-coding technology can further improve the system performance by adapting the predetermined space-time signal to the channel state. But the feedback ability of the system depends on by the antenna configuration, system bandwidth or users’speed, etc. The crux of design of the per-coding technology lies on the how to design the precoding method based on the characteristic of the feedback. The dissertation gives intensive investigation of feedback and precoding matrix design, optimization of various resources, and proposes some novel strategies as listed follows:For the design of joint precoding and network coding in multi-antenna two way relay sys-tem, the characteristics of two way relay system is first analyzed, two way relay system with network coding and precoding is proposed to improve the system performance. Then, by sharing the channel state information through channel reciprocity among users, relay and base station, a joint network coding and precoding optimization method is designed to calculate the optimal pre-coding matrix efficiently. Thereby, a joint optimization strategy based on precoding and network coding is tailored for the multi-antenna two way relay system.For the design of tradeoff between cooperative sensing and channel state information feed-back in multi-antenna cognitive system, first through analyzing the important metric of cognitive radio system, the schemes of interference eliminating towards primary users and enhancing the link performance of secondary users should be both designed. However, in the conventional multi-antenna cognitive system, the feedback channel is only implemented to enhance the link performance of the secondary user. In order to further increase the sensing performance, a coop-erative sensing method between the transmit side and receiver side of the secondary user through a feedback channel is proposed. After investigating the effect of quantization on sensing in-formation and channel state information, a tradeoff strategy of bits allocation between sensing information and channel state information is designed. It is found that, under the same amount of feedback bits, the proposed scheme can eliminate the interference towards the primary user while guarantee the link performance of the secondary user.For the design of tradeoff between spatial modulation and space time block coding, although spatial modulation or space shift keying can offer better error performance than the conventional space time block coding scheme and obtain further simplification in system design and reduction in decoding complexity, the channel correlation impacts the performance of these systems sig-nificantly. Consider channel correlation can be shown to have insignificant impact on space time coding. A Euclidean distance based switching scheme that uses the minimum Euclidean distance as the criterion for switching between space time coding and spatial modulation in MIMO sys-tems with channel correlation is proposed. The switching criterion makes a tradeoff between two transmit schemes with low complexity.For the design of adaptive space time coding scheme, a random precoding scheme which use the concept of rateless code is designed in the absence of channel state information at trans-mit side. Transmitter keeps choosing a pre-coding matrix randomly at each space-time symbol period to deliver the information until it is successfully decoded by the receiver. Then a crite-ria to achieve optimal performance by minimizing the variance of the effective channel gain is provided, the scheme based on the criteria has a better performance and could adapt to different channel conditions.
Keywords/Search Tags:Multi-antenna system, precoding, limited feedback, diversity and multiplexing, cognitive radio, two way relay, network coding, spatial modulation, space time coding, ratelesscoding
PDF Full Text Request
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