共查询到20条相似文献,搜索用时 31 毫秒
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In M-ary, Gray coded digital communication the bit error probability is usually approximated by the symbol error probability divided by the number of bits in a symbol. This approximation is known to be excellent for phase shift keying with coherent detection at high-signal-to-noise ratios and Gaussian channel. Here it is illustrated that this approximation may also be good for M-ary frequency shift keying with limiter-discriminator-integrator detection on Gaussian, Rayleigh, and Rician channels 相似文献
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现有的极化码打孔算法均未考虑信道构造过程对算法性能的影响,针对这一问题,该文提出一种基于高斯近似的极化码打孔算法(GAPPC)。首先将高斯近似作为极化码构造算法,分析高斯近似与打孔算法的关系,以降低信道构造输出值为目标,引入高斯修正因子,推导出改进的高斯近似函数。然后将改进的高斯近似函数引入信道构造,对极化子信道进行排序获得信道可靠性排序集合。最后依据信道容量关系确定映射规则,选出打孔比特集合和冻结比特集合,完成打孔极化码的构建。实验结果显示,在不同的码长和码率下,误帧率和误码率均获得显著降低。 相似文献
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In M-ary, Gray coded DPSK, and FSK with differential phase detection the bit error probability is usually approximated by the symbol error probability divided by the number of bits in a symbol. This approximation is known to be excellent for PSK with large signal-to-noise ratios in a Gaussian channel. In other cases this approximation may be questionable. Here we compute the exact values of bit error probability for DPSK and FSK in Gaussian, Rayleigh, and Rician channels. We also compute the relative error involved in this approximation. The conclusion is that except for very low values of signal-to-noise ratio the approximation is good for all channels 相似文献
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Yugang Jia Andrieu C. Piechocki R.J. Sandell M. 《Wireless Communications, IEEE Transactions on》2008,7(3):1052-1061
The multilevel structure of the N-QAM modulation constellations is exploited to significantly reduce the complexity of the sequential Gaussian approximation (SGA) algorithm for near optimal symbol detection in spatial multiplexing multiple- input multiple-output (MIMO) system. We propose two multilevel SGA algorithms (MSGA) which are based on depth- first search (DFS) and breadth-first search (BFS) respectively. Additionally, an important methodological contribution to this multilevel technique is proposed where the mismatch between the pseudo symbols and the true symbols is taken into consideration for the computation of posterior probabilities of symbol combinations. We justify this from a theoretical perspective as well as with numerical results. Simulation results show that the performance of the two proposed multilevel algorithms can approach that of the optimal a posteriori probability (APP) detector while its total computation cost is at most 81% and 48% of that of the original SGA algorithm for 16QAM and 64QAM modulation MIMO systems with 4 transmit/receive antennas respectively. 相似文献
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当信道存在时间-频率双选择性时,严重的子载波间干扰和子符号间干扰将导致广义频分复用(GFDM)系统性能显著下降.为此,该文提出一种时间偏移GFDM系统(TO-GFDM),通过对传统GFDM系统的原型滤波器进行时间偏移,来提高双选择信道下GFDM系统的性能.该文推导了GFDM信号在双选择信道中的平均信干比公式,并提出基于离散导频的联合迭代信道估计与符号检测算法,该算法利用信道估计器与串行干扰消除符号检测器之间的信息交换,逐步减小干扰信号,提高信道估计与符号检测的精度.理论分析与仿真实验结果表明,在双选择信道条件下,时间偏移GFDM比传统的GFDM具有更高的平均信干比和误码率性能;并且,联合迭代信道估计与符号检测算法能有效降低系统误码率. 相似文献
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In M-ary, Gray coded frequency shift keying with limiter discriminator detection the bit error probability is usually approximated by the symbol error probability divided by the number of bits in a symbol. This approximation is known to be excellent for phase shift keying with large energy-to-noise ratios and Gaussian channel. In other cases this may be questionable. The authors compute the exact values of bit error probability as a function of energy-to-noise-ratio per bit for Gaussian, Rayleigh and Rician channels. They also compute the relative error involved in this approximation 相似文献
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The application of the probabilistic data association (PDA) algorithm to the symbol detection in narrowband spatial multiplexed multiple input multiple output systems with known channel state information is investigated. The performance of a new proposed complex formulation of PDA algorithm, which matches the full parameters of the complex Gaussian distribution (which are the mean vector, covariance matrix and the pseudo-covariance matrix), is compared with the real vector formulation of a generalised PDA algorithm and a PDA implementation, which employs complex Gaussian approximations with matched mean and covariance only 相似文献
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当信道存在时间-频率双选择性时,严重的子载波间干扰和子符号间干扰将导致广义频分复用(GFDM)系统性能显著下降。为此,该文提出一种时间偏移GFDM系统(TO-GFDM),通过对传统GFDM系统的原型滤波器进行时间偏移,来提高双选择信道下GFDM系统的性能。该文推导了GFDM信号在双选择信道中的平均信干比公式,并提出基于离散导频的联合迭代信道估计与符号检测算法,该算法利用信道估计器与串行干扰消除符号检测器之间的信息交换,逐步减小干扰信号,提高信道估计与符号检测的精度。理论分析与仿真实验结果表明,在双选择信道条件下,时间偏移GFDM比传统的GFDM具有更高的平均信干比和误码率性能;并且,联合迭代信道估计与符号检测算法能有效降低系统误码率。 相似文献
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In the current research on intensity-modulation and direct-detection optical orthogonal frequency division multiplexing(IMDD-OOFDM) system, effective channel compensation is a key factor to improve system performance. In order to improve the efficiency of channel compensation, a deep learning-based symbol detection algorithm is proposed in this paper for IMDD-OOFDM system. Firstly, a high-speed data streams symbol synchronization algorithm based on a training sequence is used to ensure accurate ... 相似文献
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针对GMSK混合信号的单通道盲分离问题进行了研究。由于不能直接采用逐幸存路径处理(PSP)算法对GMSK混合信号进行分离,考虑对GMSK信号作线性近似处理,使得GMSK混合信号适用于PSP算法。该算法通过在符号序列和信道参数组成的联合空间进行最大似然估计,保留最优路径,输出符号对,从而获得分离信号。仿真结果表明,使用PSP算法对GMSK混合信号进行分离的误码率性能略优于粒子滤波算法误码率性能,但复杂度远低于粒子滤波算法。 相似文献
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本文提出了一种基于混合消息传递和部分高斯近似(Partial Gaussian Approximation, PGA)的多用户干扰消除方法,并应用到联合信道估计MIMO-OFDM接收机中。由于多用户干扰模型中存在的“乘积-求和”结构,使得选择标准消息传递规则,如置信传播(Belief Propagation, BP),期望传播(Expectation Propagation, EP),平均场规则(Mean Field, MF),或者联合方法时只能在性能或复杂度方面有所取舍。现有根据标准消息传递规则得到的最优性能接收机复杂度高,而近似程度大的低复杂度接收机性能损失严重。本文根据多用户干扰模型的自身特点,对标准消息传递规则进行了修改,提出了一种基于混合消息传递规则和部分高斯近似的多用户干扰消除方法。依据信道估计过程中不同用户的信道权重,采用不同的消息传递规则,可以实现复杂度和性能的均衡调整。仿真结果表明,本文提出的多用户干扰消除方法,在性能接近已知最优接收机的情况下,能够大幅降低复杂度。 相似文献
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A new technique for joint channel estimation and symbol detection in the Rayleigh flat-fading channels with impulsive noise is developed. This technique involves an approximation to the likelihood statistics for such channels, which in turn is based on the Masreliez approximation of nonlinear filtering. It is seen that the proposed detector outperforms the detector based on the Kalman filter 相似文献
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Yung-Liang Huang Chorng-Ren Sheu Chia-Chi Huang 《Selected Areas in Communications, IEEE Journal on》1999,17(10):1770-1780
We present a joint symbol, frame, and carrier synchronization method for the Eureka 147 DAB signal. Symbol timing is determined first by detecting an abrupt change in the phase angle of the complex product between the last quarter of a useful symbol and its cyclic extension in the guard interval. The detection of this abrupt change is based an the maximal likelihood (hit) principle. Frequency offset of fractional carrier spacing is estimated from the phase angle of the autocorrelation after symbol timing is estimated. Coarse frame synchronization and null symbol detection can also be achieved through this correlation information. Frequency offset of integral carrier spacing is determined from the convolution outputs between a received phase reference symbol and several locally generated but frequency-shifted phase reference symbols. We found the length of a guard interval is the most important parameter for the synchronization algorithm to work. Simulation results show that the performance of this synchronization method approaches to the ideal synchronization case in both an additive white Gaussian noise (AWGN) channel and a two-path Rayleigh fading channel 相似文献
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Mohsen Keshavarz Hedayati Hamidreza Bakhshi Mehdi Cheraghi 《Wireless Personal Communications》2013,71(2):1541-1555
In this paper, a novel semi-blind channel estimation and symbol detection based on space-alternating generalized expectation-maximization (SAGE) algorithm are proposed for space time block coded (STBC) multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) systems. At the receiver, the transmitted signals of all users are added. By utilization of SAGE algorithm, this superimposed received signals are decomposed into their signal components. Then, the channel is estimated at pilot positions. After that, the channel estimation in the other positions are obtained by interpolation and symbol detection is done by utilizing the estimated channel. In SAGE algorithm, selection of initial value is very important for the convergence. We discuss the appropriate range for selection of initial value in this paper. Simulation results show that by increasing the number of users, the slope of bit error rate curve increases with same initial value and the channel estimation becomes worse by increasing the iteration of SAGE algorithm if the initial value is not selected in the proposed rang. 相似文献
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JiangSen SunHong LiPing 《电子科学学刊(英文版)》2005,22(2):118-124
A Jointly Gaussian (JG) equalizer is derived for turbo equalization based on an augmented real matrix representation of channel model and a Gaussian approximation of the received symbol sequence. Using matrix inversion lemma and Cholesky decomposition, a lowcomplexity implementation of JG equalizer is also presented. The simulation results and complexity comparison confirm that turbo equalization with JG equalizer has a better performance and a lower complexity than the existing turbo equalization with linear minimum mean squared error equalizer. 相似文献