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Analyses And Design Of Relay Selection And Power Allocation For Two-way Relaying Networks

Posted on:2015-12-27Degree:DoctorType:Dissertation
Country:ChinaCandidate:S J LouFull Text:PDF
GTID:1228330467974590Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
With the increasing demand for wireless communications, the next generation wireless com-munication systems need to provide higher transmission rate and more reliable performance. Usingcollaboration between multiple nodes in a wireless network, cooperative communication technologyhas been shown to be a promising solution to effectively combat fading in wireless channels, andimprove the reliability of the transmission. Network coding technology can significantly improvespectral efficiency of two-way relay networks by using broadcast nature of wireless transmissionmedia. Therefore network coded two-way relay system has attracted much attention for its ability toimprove wireless network performance in recent years. This thesis focuses on the performanceanalyses and optimization design of two-way relaying systems, including relay selection schemesand power allocation schemes. The main contributions are summarized as follows.1) The performance analyses and algorithm design of relay assignment and power allocationfor multi-pair multi-relay decode-and-forward two-way relay networks. With the high sig-nal-to-noise (SNR) approximation, the two-way bit error rate (BER) of the DF-TWRN is derived inclosed-form. Based on the BER expression, the optimal power allocation scheme is proposed to ob-tain the lowest error probability. Then the power allocation scheme is applied to multi-pair mul-ti-relay two-way systems, and the two-way BER expression is obtained in closed-form throughmathematical manipulations. Theoretical analyses and simulation results show that the proposedscheme can obtain better BER performance at low complexity cost.2) On the design of joint relay selection and power allocation for two-way AF relay networkswith asymmetric traffic requirements (ATR). We focus on analyses of two-way end-to-end SNRwhile there exists asymmetric target rates on the different directions. Based on the results, a newpower allocation algorithm is proposed through hypothesis testing under total transmit power con-straint, and the corresponding relay selection criteria based on the optimal algorithm is proposed aswell. Two new approximation methods are proposed to evaluate the outage probability with moreaccuracy. Finally the closed-form expressions (or upper and lower bound) of the proposed joint al-gorithm are derived by theoretical analyses. The simulation results confirm the theoretical analyses,and meanwhile show that the proposed scheme can obtain lower outage probability than previousschemes in ATR AF-TWRN networks.3) Analyses and design of multiple relay selection scheme for outdated channel state infor-mation (CSI) two-way AF relaying systems. First of all the outdated CSI AF-TWRN model is es- tablished, a normalized threshold generalized selection combining (NT-GSC) scheme is proposedfor two-way communication. The upper and lower bounds of outage probability, average BER andergodic capacity are obtained by reasonable approximation to derive the diversity gain of the pro-posed multiple relay selection scheme. Then based on the analyses and comparison of performance,an adaptive multiple relay selection scheme is proposed to help the system to choose appropriatenumber of relays. The simulation results show that comparing with conventional opportunistic relayselection (ORS), the proposed multiple relay selection can obtain higher diversity gain for outdatedCSI two-way networks, and the adaptive selection scheme can effectively reduce the ergodic capac-ity loss, which is caused by more channel occupation during multiple relay cooperative process.
Keywords/Search Tags:Two-way relaying networks, Network coding, Outage probability, Bit error rate, Relayselection, Power allocation, Asymmetric traffic requirements, Oudated channel stateinformation
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