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1.
In this letter, outage probability of dual-hop decode-and-forward (DF) relaying scheme is analyzed over mixed Rayleigh and generalized Gamma fading channels. Cooperation model considered in this work consists of a source, a relay and a destination. It is assumed that source-relay and relay-destination channels experience Rayleigh fading and generalized Gamma fading, respectively. Exact outage probability expression is derived and outage performance is illustrated for both direct transmission and DF relaying scheme. 相似文献
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Distributed spatial diversity systems utilize multiple communication nodes to create independent signal replicas that are combined at the destination. Practical diversity receivers often employ simple combining techniques especially if comparable performance to more complex optimum combining can be achieved. The performance of decode-and-forward relaying that uses selection combining is investigated. In particular, a closed- form expression for the outage probability of a system with an arbitrary number of relay nodes is derived. By comparing the performance of a system that uses selection combining to one that uses optimum maximal ratio combining, it is shown that the performance loss due to using a less complex combiner is not substantial. 相似文献
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This paper considers the choice of the number of diversity branches for minimizing the bit error rate of a selection diversity system using noncoherent binary frequency-shift keying modulation for transmission over a Rayleigh fading Gaussian channel. An exact expression for the optimum number of branches,L_{sel}^{ast} , is given. The resulting probability of bit error decreases exponentially with the square root of the energy per bit. 相似文献
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研究存在残余自干扰(residual self-interference, RSI)条件下全双工解码转发中继的中断概率性能。在Nakagami-m信道下,推导了多跳解码转发(multi-hop decode-and-forward,MH-DF)策略和选择解码转发(selected decode-and-forward,SDF)策略的端到端中断概率闭合表达式和渐近表达式,分析了两种策略的可达分集度。结果显示,MH-DF策略的可达分集度为0,SDF策略的可达分集度由信道成型因子和中继功率伸缩方案决定。相比于MH-DF策略,SDF策略具有更优的中断概率性能和抗自干扰能力。 相似文献
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Analysis of Transmit Antenna Selection/Maximal-Ratio Combining in Rayleigh Fading Channels 总被引:11,自引:0,他引:11
《Vehicular Technology, IEEE Transactions on》2005,54(4):1312-1321
In this paper, we investigate a multiple-input-multiple-output (MIMO) scheme combining transmit antenna selection and receiver maximal-ratio combining (the TAS/MRC scheme). In this scheme, a single transmit antenna, which maximizes the total received signal power at the receiver, is selected for uncoded transmission. The closed-form outage probability of the system with transmit antenna selection is presented. The bit error rate (BER) of the TAS/MRC scheme is derived for binary phase-shift keying (BPSK) in flat Rayleigh fading channels. The BER analysis demonstrates that the TAS/MRC scheme can achieve a full diversity order at high signal-to-noise ratios (SNRs), as if all the transmit antennas were used. The average SNR gain of the TAS/MRC is quantified and compared with those of uncoded receiver MRC and space-time block codes (STBCs). The analytical results are verified by simulation. It is shown that the TAS/MRC scheme outperforms some more complex space-time codes of the same spectral efficiency. The cost of the improved performance is a low-rate feedback channel. We also show that channel estimation errors based on pilot symbols have no impact on the diversity order over quasi-static fading channels. 相似文献
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由于在数字移动通信中要考虑多径和多普勒频移的影响,建立了瑞利时变衰落信道模型,并使用最大似然序列检测算法实现均衡.它的基本思想是在MLSE算法中插入信道估计算法,不断跟踪实时信道变化并及时更新.为降低复杂度,研究了传统的自适应MLSE算法和运幸存MLSE两种经典算法,仿真表明,当多普勒频移较小时,两种算法有相近的性能,... 相似文献
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Interest in code division multiple access (CDMA) has increased dramaticallyin boththe industry and academia. This is due to the potential increase in usercapacity andinterference, multipath fading, and jam-resistant capabilities. Differentapproaches ofmultiuser detection schemes have shown improvement over the conventionalreceiver.However, multiuser detectors require system parameters and adaptive multiuserreceivers require training sequences. These parameters are difficult toobtain inmultipath fading channels with a degradation in performance. A blind adaptivemultiuser receiver for flat fading and frequency-selective fading environments isstudied in this paper. This receiver alleviates the problem of multiuser detectors and adaptivemultiuser receivers by using a blind adaptive equalization method. The structure of the receiveris similar to that of the adaptive MMSE receiver which consists of an adaptive equalizer and an adaptivemechanism that uses a standard least mean-squared (LMS) algorithm, but uses a matched filterto generate a reference signal. The receiver is shown to be effective in different fadingchannels with perfect power control and a near-far effect. Furthermore, the simulationresults show that the blind MMSE receiver outperforms the conventional receiver and theRAKE receiver. 相似文献
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In this paper, some analytical results for general order selection (GOS) over independent but not necessarily identically distributed (i.n.d.) Weibull and Nakagami fading channels are presented. The Weibull fading parameters are assumed to be equal whereas the Nakagami fading parameters are assumed to be integer-valued. It is shown that the pdf of the q-th order statistic can be expressed as a linear combination of Weibull and Nakagami pdf's respectively. Closed-form expressions for the moment generating functions and general moments are derived. In addition, exact closed-form expressions for the symbol error rate are obtained for a number of modulation schemes. Numerical results show that for the same average channel gains, the performance on i.n.d. channels may be better or worse than on i.i.d. channels. 相似文献
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A modulation system is proposed that continuously adjusts its data rate in response to signal strength variations in a fading channel. The optimum variation of data rate with channel conditions is determined, and includes the effects of feedback channel time delay, the interval between rate changes, and restriction of the number of allowable rates. Application of these results to a full duplex situation allows determination of the optimum fraction of the data stream to be devoted to service information. Comparison of this scheme with diversity transmission on the basis of error probability and bandwidth utilization reveals a reduction on the order of 14 dB in transmitter power for a typical duplex link. 相似文献
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Sungeun Lee Myeongsu Han Daesik Hong 《Wireless Communications, IEEE Transactions on》2009,8(6):2807-2812
In the paper, we deal with a single-selection opportunistic relaying with the decode-and-forward (DF) protocol over Rayleigh fading channels. The exact end-to-end average signalto- noise ratios (SNR) and ergodic capacities of both proactive and reactive opportunistic relaying are derived as a closed-form for arbitrary link SNR. In addition, the effective ergodic capacity satisfying the minimum required data rate without outage is also identified for both relaying schemes. The analysis results are used to demonstrate which relaying scheme outperforms the other for given system parameters. 相似文献
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In this letter, we address the end-to-end signal-to-noise ratio (SNR) gain achievable by dual-hop relaying over the single-hop transmission in single-input single-output (SISO) flat Rayleigh fading channels. We deal with both nonregenerative and regenerative relaying schemes. To quantify the SNR gain, a closed-form expression of the probability of SNR gain is developed. The probability of SNR gain results in an explicit function of an average power ratio of the per-hop channel in dual-hop relaying to the channel in the single-hop transmission. We investigate impacts of the average power ratio as well as the relaying location on the SNR gain. 相似文献
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This paper proposes a modified decode and forward (DAF) protocol with a three node model, which contains two users and one destination. Each user can be either the source or the relay in different frames. We analyze the four cooperative cases in the first frame and run simulations to obtain the optimal power allocation coefficients in the second frame. The closed form expression of outage probability is derived over Nakagami m fading channels. Furthermore, we show that the proposed model has better performance than the non cooperation system and traditional DAF strategy based on the derived outage probability. 相似文献
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本文设计了一种新的MIMO传输技术,它在发射端(基站)按最大比发射(MRT),接收端则基于信噪比最大的原则仅选择一根接收天线来处理信号,记MRT/RAS.其目标就是为了提高系统性能并降低接收端(移动台)的硬件复杂度.根据随机矩阵和排序统计的最新理论,推导出瑞利衰落信道下MRT/RAS系统的中断概率、误码率(BER)等性能指标的确切表达式.仿真结果表明MRT/RAS系统可以取得很好的阵列增益及满分集增益.仿真试验也证明了分析结果的正确性. 相似文献
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It is well known that the capacity of spatial multiplexing multiple-input multiple-output (SM-MIMO) system employing optimal antenna selection can significantly outperform a system without selection for same number of costly radio frequency chains. However, it requires an exhaustive search for the optimal selection (OS) that grows exponentially with the available number of transmit (u) and receive (m) antennas. In this paper, a novel low complexity receive antenna selection (RAS) technique is proposed for SM-MIMO to maximize the channel capacity over correlated Rayleigh fading environment. It is based on the Euclidean norms of channel matrix rows and the corresponding phase differences due to their direct impact on the capacity. Extensive analysis and simulations have shown near optimal performance for any signal-to-noise-ratio and correlation values with low complexity of ${\mathcal{O} \left({u^{2}m}\right)}$ vector calculations. This technique provides fast RAS to capture most of the capacity gain promised by multiple antenna systems over different channel conditions. Furthermore, it enables efficient spectrum utilization for next generation wireless communications. 相似文献
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Wireless Personal Communications - Adaptive transmission in a cooperative network with a half-duplex relay operating in decode-and-forward mode is considered. The main purpose of the paper is... 相似文献
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Adaptive Path Selection Scheme with Combining for Multiple Relaying Cooperative Communications Networks
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In future communications, cooperative communications with relay networks will be one of the most effective schemes to enlarge the coverage area and to boost the data rate. In the recent research results, the path selection, power allocation, and relay protocols on relay networks are the most important factors to improve the system performance. However, the channel quality of the direct transmission path and the relaying path has an influential effect on the performance of relay networks. Therefore, in this paper, we propose a best relaying path selection (BRPS) scheme to obtain the path diversity to improve the system capacity and data rate for cooperative networks (CNs). Simulation results show that the more the relay nodes are selected, the lower the bit error rate (BER) is. The proposed BRPS scheme obtains a high concession between both BER and system capacity for CNs. 相似文献
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We present the performance of multi-antenna selective combining amplify-and-forward (SC-AF) two-way relaying systems over independent and identically distributed (i.i.d) Nakagami- $m$ fading channels. The outage probability and symbol error probability of our relaying system are derived in closed-form. In order to get additional insights into the impact of system parameters, we consider the analysis of system at high signal-to-noise (SNR) regime. Through over high SNR analysis, we assume that the fading channels are independent and non-identically distributed (i.n.i.d). Also, there is no assumption on the fading parameter, $m$ . Moreover, some special cases of practical interest (e.g., Rayleigh fading channels, and single relay system) are also examined. Subsequently, we define an optimization problem using some approximations and then solve it analytically. Lastly, we present numerical simulations to check our analytical formulas. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(3):944-951