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Based on imperfect channel state information (CSI) and relay selection, a cross-layer optimization scheme is developed for cooperative MIMO system, and the corresponding system performance is investigated in Rayleigh fading channel. By the theoretical analysis and mathematical manipulation, the average spectral efficiency (SE), packet error rate (PER) and packet loss rate (PLR) are derived. As a result, closed-form expressions of the average SE, PER and PLR are obtained, respectively. According to these, a cross-layer design (CLD) scheme subject to the average PER constraints is proposed to avoid the SE performance loss caused by the conventional instantaneous PER constraints. The scheme optimizes the adaptive thresholds by maximizing the average SE of the system, and an iteration method joint the Lagrange multiplier and Newton methods is presented to solve the above optimization problem. Simulation results verify the validity of the theoretical analysis. The results show that the proposed CLD scheme can improve the SE while target PLR is maintained. The CLD scheme under average PER constraints has higher SE than the conventional CLD scheme under instantaneous PER constraints. 相似文献
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M. Naeem D.C. Lee 《Engineering Applications of Artificial Intelligence》2011,24(6):1046-1051
In this paper, we present a low-complexity algorithm for real-time joint transmit and receive antenna selection in MIMO systems. The computational complexity of exhaustive search in this problem grows exponentially with the number of transmit and receive antennas. We apply Binary Particle Swarm Optimization (BPSO) to the joint transmit and receive antenna selection problem. In addition, applying the general BPSO to joint antenna selection, we also present a specific improvement to this population-based heuristic algorithm, namely, we feed cyclically shifted initial population so that the average convergence time (the number of iterations until reaching an acceptable solution) is reduced. The proposed BPSO for joint antenna selection problem has a low computational complexity, and its effectiveness is verified through simulation results. 相似文献
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分别针对瑞利衰落信道和Nakagami衰落信道,研究了使用发射天线选择(TAS)和正交空时分组码(STBC)的多输入多输出系统的平均符号误码率(ASEP)性能。基于标量加性高斯白噪声(AWGN)信道的方法,推导出了采用脉冲幅度调制(PAM)、相移键控(PSK)和正交幅度调制(QAM)的精确和近似的ASEP闭合表达式。然后对不同条件下的系统性能做了数值仿真,验证了分析结果的正确性。 相似文献
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Multimedia Tools and Applications - Due to mobile-to-mobile (M2M) communication unpredictability and difficulty in securing reliable channels, transmission of video over M2M networks is... 相似文献
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This paper investigates a multi-pair full-duplex(FD) communication system aided by an active reconfigurable intelligent surface(RIS) with spatial correlation and imperfect channel state information(CSI).We apply the linear minimum mean square error(LMMSE) method to estimate the cascaded user-RIS-user channel. The approximation for the sum achievable rate(ACR) is derived in closed form over correlated Rician fading channels. To provide insights in a poor-scattering environment, the sum ACR limits... 相似文献
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Hoang-Yang Lu 《Applied Soft Computing》2012,12(7):1865-1874
This paper presents a novel relay resource utilization scheme that uses the particle swarm optimization (PSO) algorithm to jointly search the antenna combining (AC) matrices of multiple relays in cooperative MIMO systems. The relays use the AC matrices to weight and combine signals transmitted by the source node, and then forward the weighted signal to the destination node. As a result, the relays can reduce the number of radio frequency (RF) chains used by the transmit/receive antenna elements, and thereby lower the hardware costs of deploying RF chains. Furthermore, because there are fewer RF chains, the relays require less power than relays that use all the RF chains The results of computer simulations demonstrate that the proposed scheme outperforms the full RF-chain relay method and existing approaches in some scenarios. 相似文献
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提出了一种基于最大瞬时信噪比在瑞利衰落信道中的多发多收(MIMO)天线系统的简单联合收发天线算法.在选定两个发送天线和一个接收天线情况下,利用Alamouti编码可以获得二进制相移键控(BPSK)的误码率(BER)精确解,该分析结果通过仿真得到确切验证. 相似文献
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Cognitive radio networks have recently attracted significant research attention owing to their promise for application in future cellular communication. In this light, given the intense power consumption of wireless networks, considerable research is now being directed at designing random cognitive radio networks with enhanced energy efficiency. In this study, we investigate the outage probability and energy efficiency in a cognitive radio network, modeling the locations of the primary users and cognitive users as a Poisson point process. We derive closed-form expressions for the outage probability and energy efficiency with consideration of the probabilities of unoccupied (not utilized by the primary users) channel selection and successful transmission for imperfect detection in an interference-limited environment of cognitive radio network. Furthermore, we propose a transmit antenna selection method for the cognitive transmitter in such networks and accordingly develop closed-form expressions for the outage probability and energy efficiency. The study reported here highlights the importance of combining the capabilities of unoccupied channel selection and successful transmission in cognitive radio networks to achieve optimal performance regarding outage probability and energy efficiency. In terms of energy efficiency, there is an optimal threshold that maximizes the energy efficiency. For implementation in transmit antenna selection, the outage probability can be significantly decreased by increasing the number of transmit antennas, even though the energy efficiency is maximized at the target outage probability. 相似文献
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针对多输入多输出(MIMO)无线系统多空时发射分集(STTD)技术的符号检测问题,提出了一种有效的功率分配算法。该算法基于QR连续符号检测,在只需要少量反馈信道状态信息(CSI)的前提下对信道矩阵进行QR分解。对R矩阵的属性进行了统计分析,推导了平均误码率(BER)的闭环表达式与上界;通过最小化平均BER上界,给出了最优化的功率分配机制。详细的仿真实验及与现有算法的比较表明,提出算法的性能不仅与理论值完全吻合,而且具有更好的BER性能。 相似文献
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In this paper,the per-layer design for Tomlinson-Harashima precoding (THP) in the downlink of multiuser multiple-input multiple-output (MIMO) systems is investigated.In these systems,the number of the receivers is equal to that of the transmit antennas.Based on the criterion of maximum system sum-capacity,we study two per-layer joint transmit and receive filters design schemes with receive antenna beamforming (RAB) and receive antenna selection (RAS),respectively.Moreover,the differences of the equivalent channel gains and capacities between these two schemes are analyzed theoretically.Simulation results show that by these per-layer schemes,the system sum-rate is improved significantly with respect to the per-user processing scheme. 相似文献
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In a time-division duplex (TDD) system with massive multiple input multiple output (MIMO), channel reciprocity calibration (RC) is generally required in order to cope with the reciprocity mismatch between the uplink and downlink channel state information. Currently, evaluating the achievable spectral efficiency (SE) and energy efficiency (EE) of TDD massive MIMO systems with imperfect RC (IRC) mainly relies on exhausting Monte Carlo simulations and it is infeasible to precisely and concisely quantify the achievable SE and EE with IRC. In this study, a novel method is presented for tightly bounding the achievable SE of massive MIMO systems with zero-forcing beamforming under IRC. On the basis of the analytical results, we demonstrate key insights for practical system design with IRC in three aspects: the scaling rule for interference power, saturation region of the SE, and the bound on the SE loss. Finally, the trade-off between spectral and energy efficiencies in the presence of IRC is determined with algorithms developed to optimize SE (EE) under a constrained EE (SE) value. The loss of optimal total SE and EE due to IRC is also quantified, which shows that the loss of optimal EE is more sensitive to IRC in a typical range of transmit power values. 相似文献
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Automatic Repeat reQuest (ARQ) is a promising forward error control mechanism for improving the reliability of data transmission over wireless channels. Traffic self-similarity has been discovered to be a ubiquitous phenomenon in communication networks with a significant impact on the network performance and user-perceived Quality-of-Service (QoS). However, due to the high complexity and challenges of modelling traffic self-similarity, there has not been any analytical model reported for ARQ under self-similar traffic. To fill this gap, we develop a novel analytical model of multi-buffer ARQ systems in the presence of prioritized self-similar traffic for reliable data transmission and QoS differentiation. This model can be used to investigate the probabilities of queueing loss and transmission loss in the multi-buffer ARQ systems. The validity of the analytical model is demonstrated via extensive comparison between analytical and simulation results. The model is further adopted to investigate the effects of service capacity and delay bound of ARQ on the system performance. 相似文献
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通过对非理想频谱感知下的认知无线电网络(CognitiveRadioNetwork,CRN)建模,分析了认知网络的主要性能参数。由于漏检的存在,可能造成主次级用户业务之间的碰撞,从而引起用户业务的中断或阻塞;另一方面,由于虚警,认知用户将放弃接入可用的空闲频段,从而降低了频谱资源的利用率,无论哪种情形都将导致系统的QoS性能降低。通过将认知网络建模成一个二维马氏链,推导了系统的主要QoS参数。结果表明,尽管误检的存在,认知网络仍能显著提高频谱资源利用率;而主用户的QoS需求也可以通过控制认知业务的接入量来得到保证。 相似文献
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A structure was proposed for multiple-input-multiple-output multicarrier code divi- sion multiple access (MIMO MC-CDMA) uplink transmission system. Linear zero- forcing V-BLAST (ZF V-BLAST) algorithm and maximum ratio combining (MRC) scheme was applied to the receivers. The average bit error rate (BER) expression was derived on condition that the number of receive antennas was larger than that of transmit antennas and it was verified by simulations. Numerical results show that the number of transmit and receive antennas, as well as the number of sub- carriers, all exert significant effects on the BER performance. The space diversity and frequency diversity show different abilities to improve the BER performance. The MIMO MC-CDMA system based on linear ZF V-BLAST algorithm is capable of achieving better BER performance than that of the conventional MC-CDMA system by reducing the number of transmit antennas or increasing the number of receive antennas. 相似文献