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该文提出了一种基于判决反馈思想的DF-PSP单通道盲分离算法。该算法结合判决反馈的思想,利用Viterbi序列检测器最可能的幸存序列得到的预判决来合成信道冲激响应尾部造成的符号串扰,来弥补现有PSP单通道盲分离算法对信道冲激响应进行截断处理而带来的性能损失。仿真结果表明,对于两路混合QPSK信号,该算法较截断PSP单通道盲分离算法在复杂度相当的条件下有更好的性能,在误码率为 时,信噪比改善可达到2dB左右,且在同等过采样条件下,该算法能获得更好的性能提升。 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(11):5059-5067
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Guang-Guo Bi 《Communications, IEEE Transactions on》1983,31(10):1196-1201
Performance of the threshold coherent frame sync acquisition (TCFSA) algorithm on the AWGN channel is analyzed and compared with the performance of the algorithm for the BSC. Cases both with and without binary phase ambiguity are considered. Analytical and simulation results are presented and the agreement between the two is shown to he very close. It is shown that the threshold frame sync acquisition algorithm on the BSC outperforms the TCFSA algorithm on the AWGN channel whenP_{e} leq 0.1 , while it is inferior whenP_{e} geq 0.13 in cases of practical interest. A modified acquisition algorithm on the AWGN channel is then proposed. Analytical and simulation results for the modified algorithm show that it is superior to conventional algorithms on the BSC and the AWGN channel. 相似文献
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判决反馈均衡器(Decision Feedback Equalizer,DFE)能补偿具有严重符号间干扰(Inter Symbol Interference,ISI)的信道,且不存在线性均衡器增强噪声的影响。而在其基础上改进的运用误差反馈的DFE,可利用误差反馈滤波器来减少传统DFE中存在的误差信号的相关性,同时其硬件实现的复杂度没有明显提高。理论分析和仿真表明,这种方法比传统的DFE更有效,特别是针对信道有严重符号间干扰的情况。 相似文献
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空间耦合LDPC(Spatially Coupled LDPC,SC-LDPC)码由于阈值饱和特性,被证明是未来无线通信系统的有力候选码型。SC-LDPC码是一种卷积LDPC码,在二元无记忆对称信道下采用置信传播译码算法时具有逼近香农限的性能。对SC-LDPC码的构造及其经典的置信传播译码算法进行了阐述,并在加性高斯白噪声信道下进行了性能仿真和分析。仿真结果表明,SC-LDPC码的约束长度越长或最大迭代次数越大,其性能就越逼近香农容量限。SC-LDPC码在误码率为10-5、最大迭代次数为100时,码长20 000比码长10 000大约有0. 68 d B的增益;在误码率为10-5、码长为10000时,最大迭代次数100的SC-LDPC码比最大迭代次数10的码大约有0. 66 d B的增益。仿真结果有效验证了SCLDPC码在无线通信系统中的良好性能。 相似文献
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Permuter H. Cuff P. Van Roy B. Weissman T. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(7):3150-3165
We establish that the feedback capacity of the trapdoor channel is the logarithm of the golden ratio and provide a simple communication scheme that achieves capacity. As part of the analysis, we formulate a class of dynamic programs that characterize capacities of unifilar finite-state channels. The trapdoor channel is an instance that admits a simple closed-form solution. 相似文献
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广义时频二维扩频在加性白高斯噪声信道中的性能 总被引:12,自引:2,他引:10
该文提出了一种广义时频二维扩频的概念。在加性白高斯噪声信道中,给出了这种二维扩频通信方式的发射机、接收机工作原理,分析了二维扩频通信方式的误比特率,同时,给出了二维扩频通信方法的误比特率的仿真结果.结果表明,分析结果与仿真结果相近。 相似文献
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《Communications, IEEE Transactions on》2006,54(3):574-574
Outage Minimization With Limited Feedback for the Fading Relay Channel In this paper, we consider practical methods to approach the theoretical performance limits in the fading relay channel under different assumptions of transmitter channel knowledge. Specifically, we consider two degrees of transmitter channel knowledge: 1) perfect feedback is available and power control is employed; and 2) no channel-state knowledge is available at the transmitters, and only spatial power allocation is possible. First, when perfect feedback is available, the optimal power-control policy determines the ultimate limits of performance for constant-rate transmission in the slow fading environment. However, in practice, perfect channel knowledge is not possible at the transmitters due to the finite capacity of the feedback links. We find practical methods to approach this performance limit through the use of power control with finite-rate feedback. The finite-rate feedback results are shown for the low-complexity, full-diversity amplify-and-forward (AF) protocol. Interestingly, we see that only a few feedback bits are needed to achieve most of the gains of the optimal perfect feedback power-control algorithm. Second, we consider the performance limit when the transmitter has no channel-state knowledge, and derive the optimal spatial power allocation between the source and relay for a given sum power constraint for the AF protocol. In the foremost practical cases of interest, equal power allocation between the source and relay is shown to be nearly optimal. Our work suggests that there is minimal power savings from using spatial power allocation at the transmitters. To obtain large performance improvements over constant power transmission, it is imperative to have feedback for each realization of the channel state to allow for temporal power control. 相似文献
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This paper presents a derivation of the noise performance of the cross-product AFC with decision feedback (CPAFCDF). This is an AFC loop configured for use with differentially phase-shift-keyed (DPSK) signals and gives excellent performance in noise. 相似文献
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Practical Multiuser Diversity With Outdated Channel Feedback 总被引:2,自引:0,他引:2
《Vehicular Technology, IEEE Transactions on》2005,54(4):1334-1345
Inspired by the information theoretic results concerning multiuser diversity, we address practical issues in implementing multiuser diversity in a multiple access wireless setting. Considering a channel-assigning strategy that assigns the channel only to the user with the best instantaneous SNR [3], our emphasis is on the effects of channel feedback delay in downlink transmissions. A finite set of M-ary quadrature amplitude modulation (M-QAM) constellations is adopted and a constant transmit power is assumed in this practical multiuser adaptive modulation scheme. Based on the closed-form expressions for average bit error rate (BER) and average data rate, we illustrate the impact of channel feedback delay on the achievable multiuser diversity gain with the number of users. Simple and accurate asymptotic approximations are also provided in the limit of large numbers of users. Focusing on different applications, we propose two optimization criteria for the switching thresholds, based on either an average BER, or an outage probability constraint. Two novel constant power, variable rate M-QAM schemes that are less sensitive to feedback delay are proposed using the optimal switching thresholds, which are derived to maximize the average data rate subject to these two constraints, respectively. To obtain a certain degree of fairness among the users, we also consider a fair channel-assigning strategy that assigns the channel to only the user with the greatest normalized SNR. 相似文献
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Iterative decoding and channel estimation for space-time BICM over MIMO block fading multipath AWGN channel 总被引:1,自引:0,他引:1
In this paper, we consider a generic model of space-time bit-interleaved coded modulation (ST-BICM) on a multiple-input multiple-output (MIMO) Rayleigh fading multipath channel. A practical low-complexity receiver structure performing iteratively MIMO data detection, channel decoding and channel estimation, is presented. The MIMO data detection, employing a reduced-state list-type soft output Viterbi algorithm enables to cope with severe channel intersymbol interference (ISI) without MIMO prefiltering. Among other results, simulations show that our approach can dramatically improve the downlink performance of time-division multiple access (TDMA) systems with high order modulation, keeping a reasonable complexity at the receiver side. 相似文献
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A cumulative decision scheme that can be employed in a feedback communication system is treated. Any decision to decode depends upon all messages that have been received prior to the decision. The average error over all transmissions as well as the forward error may be controlled. Performance is compared to an error-detection repeat-request noncumulative scheme utilizing group codes. Optimal performance of the cumulative scheme with respect to the noncumulative scheme is given for short-length best group codes. It is also demonstrated that the use of feedback does not necessarily increase appreciably the amount of hardware necessary to effect error control. 相似文献
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常规跳频系统发送的调制信号易被干扰损伤。本文提出一种新的多序列跳频系统,无需对载波进行调制,数据分组从一簇相互正交的跳频序列中选出某一跳频序列,该跳频序列的当前频率由射频端直接发送。相比差分跳频,多序列跳频的发送频率不仅是用户数据的函数,也是跳频序列的函数,增加了对发送频率的约束,因此可以采用窄带接收,更好地抑制了带外干扰。在AWGN信道下简要讨论了多序列跳频抗跟踪干扰性能,重点分析了其抗部分频带干扰性能。计算和仿真表明,多序列跳频受跟踪干扰影响不大;最坏部分频带干扰下,误码率为10^-5要求的信干比,MSFH比DFH低约1.5dB,比常规跳频低约2.5dB。 相似文献
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This paper addresses the issue of advanced equalization methods for space-time communications over multiple-input multiple-output block fading channel with intersymbol interference. Instead of resorting to conventional multiuser detection techniques (based on the straightforward analogy between antennas and users), we adopt a different point of view, and separate time equalization from space equalization, thus introducing a higher degree of freedom in the overall space-time equalizer design. Time-domain equalization relies on minimum mean-square error criterion and operates on multidimensional modulation symbols, whose individual components can be detected in accordance with another criterion. In particular, when the optimum maximum a posteriori criterion is chosen, substantial performance gains over conventional space-time turbo equalization have been observed for different transmission scenarios, at the price of an increased, albeit manageable, computational complexity. 相似文献