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RISS 인기검색어
- 검색키워드
- 저자 : Tsiftsis, Theodoros A. (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
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Semiblind Iterative Receiver for Coded MIMO-OFDM Systems
Kyeong Jin Kim,Tsiftsis, T. A.,Schober, R. IEEE 2011 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.60 No.7
<P>In this paper, a semiblind iterative receiver is proposed for coded multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. A novel iterative extended soft-recursive least square (IES-RLS) estimator for joint channel and frequency offset estimation is introduced. Extrinsic bit information obtained from the channel decoder and expected symbol decisions obtained from the demodulator are simultaneously exploited by the IES-RLS. The proposed receiver combines the MIMO data demodulator, the proposed channel estimator, and the channel decoder in an iterative manner to yield an improved bit error rate (BER) performance. To arrive at a feasible algorithm, the first-order linearization of the received vector signal with respect to the frequency offset is used in the IES-RLS channel estimator. The BER performance, a constellation-constrained mutual information analysis, and an EXIT chart analysis are used to verify the effectiveness of the proposed receiver. Simulation results show the superiority of the proposed semiblind receiver, compared with conventional semiblind receivers.</P>
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Power Allocation in Cyclic Prefixed Single-Carrier Relaying Systems
Kyeong Jin Kim,Tsiftsis, T. A.,Poor, H. V. IEEE 2011 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.10 No.7
<P>To address the issues of high peak-to-average power ratio and high power backing-off in orthogonal frequency-division multiplexing (OFDM) relaying systems, a cyclic prefixed single-carrier (CP-SC) relaying system employing best terminal selection (BTS) is considered in this paper. Under a system power constraint, the problem of joint optimal power allocation to the source and relay is investigated. For a two-hop amplify-and-forward (AF) relaying protocol, the optimal power allocation is first obtained by maximizing the achievable spectral efficiency. After applying the obtained optimal power allocations to the source and relay, a destination terminal that has the best effective end-to-end signal-to-noise ratio is selected. With the help of the statistical properties of circulant channel matrices in the relay links, closed-form bounds for the maximum achievable spectral efficiency, outage probability, and average symbol error rate (ASER) are derived. Further, an asymptotic analysis of the outage probability and ASER is conducted and it is shown that both the number of terminals in the system and the number of channel taps being supported by the CP length play key roles in determining the overall diversity gain. Monte Carlo simulation results verify the derived closed-form analytical expressions.</P>
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Secrecy Performance of Finite-Sized Cooperative Full-Duplex Relay Systems With Unreliable Backhauls
Hongwu Liu,Kyeong Jin Kim,Tsiftsis, Theodoros A.,Kyung Sup Kwak,Poor, H. Vincent Institute of Electrical and Electronics Engineers 2017 IEEE transactions on signal processing Vol.65 No.23
<P>This paper investigates secrecy performance of finitesized cooperative full-duplex relay (FDR) systems with unreliable wireless backhaul connections across multiple transmitters under Nakagami-m fading. Closed-form expressions for the secrecy outage probability and probability of nonzero achievable secrecy rate are derived in terms of self-interference (SI), transmitter cooperation, and backhaul reliability. It is shown that transmitter cooperation can effectively enhance the secrecy performance, while the asymptotic limits on the secrecy outage probability and probability of nonzero achievable secrecy rate are exclusively determined by backhaul reliability. With the aid of transmitter cooperation, the burden of SI cancelation can be alleviated for the FDR system in achieving the smallest allowed secrecy outage probability. Compared to that of a half-duplex relay (HDR) system, the FDR system achieves a lower secrecy outage probability with well suppressed SI. The analysis shows that the secrecy outage probability achieved by the FDR system converges to that of the HDR system under perfect backhaul as the target secrecy rate becomes small. The secrecy performance metrics of the considered system are verified by simulations for various backhaul scenarios.</P>
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On the Performance of Cyclic-Prefixed Single-Carrier Cellular Systems in Cochannel Interference
Kyeong Jin Kim,Yongzhao Li,Tsiftsis, T. A. IEEE 2011 IEEE Transactions on Vehicular Technology VT Vol.60 No.8
<P>In this paper, we study cyclic-prefixed single-carrier cellular systems in the presence of cochannel interference from neighboring cells. Performance analysis for the maximum achievable average rate and outage probability based on approximated distributions for the signal-to-interference-plus-noise ratio (SINR) is presented. An asymptotic diversity gain is also derived. Monte Carlo simulations verify the derived analytical expressions.</P>
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Rate-Splitting for Intelligent Reflecting Surface-Assisted CR-NOMA Systems
You, Haoyu,Hongwu, Liu,Bai, Zhiquan,Tsiftsis, Theodoros,Kwak, Kyung Sup 한국통신학회 2023 Journal of communications and networks Vol.25 No.1
Intelligent reflecting surface (IRS) has been re-garded as promising technique to improve system performancefor wireless communications. In this paper, we propose a rate-splitting (RS) scheme for an IRS-assisted cognitive radio-inspirednon-orthogonal multiple access (CR-NOMA) system, where theprimary user’s (PU’s) quality of service (QoS) requirementsmust be guaranteed to be same as in orthogonal multipleaccess. Assisted by IRS, the threshold for the PU’s tolerableinterference power is improved, which in turn makes it possibleto increase the achievable rate for the secondary user (SU). The optimal transmit power allocation, target rate allocation,and successive interference cancellation (SIC) decoding order arejointly designed for the proposed RS scheme. Taking into accountthe statistics of the direct link and IRS reflecting channels, closed-form expression for the PU’s and SU’s outage probabilities arerespectively derived. Various simulation results are presentedto clarify the enhanced outage performance achieved by theproposed RS scheme over the existing CR-NOMA and IRS-assisted CR-NOMA schemes.
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Qi, Nan,Wang, Wei,Ye, Diliao,Wang, Mei,Tsiftsis, Theodoros A.,Yao, Rugui Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.3
In this paper, we propose an energy-efficient unmanned aerial vehicle (UAV) relaying network. In this network, the channels between UAVs and ground transceivers are model-free. A UAV acting as a flying relay explores better channels to assist in efficient data delivery between two ground nodes. The full-duplex relaying mode is applied for potential energy efficiency (EE) improvements. With the genetic algorithm, we manage to optimize the UAV trajectory for any arbitrary radio map scenario. Numerical results demonstrate that compared to other schemes (eg, fixed trajectory/speed policies), the proposed algorithm performs better in terms of EE. Additionally, the impact of self-interference on average EE is also investigated.
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