共查询到20条相似文献,搜索用时 31 毫秒
1.
A model-based approach for the decision feedback equalization of Volterra type nonlinear communication channels is proposed such that the linear model-based decision feedback equalization can be considered as a special case of the proposed approach. In designing the decision feedback equalizer, the nonlinear decision feedback equalization problem is visualized as a linear, multichannel equalization problem. A complete modified Gram–Schmidt orthogonalization of the input vector is achieved by using modified sequential processing multichannel lattice stages. The elements of the multichannel desired signal vector are then estimated from the new orthogonal set by using only scalar operations. The probability of error performance of the proposed equalizer is improved by the estimation of the elements of the desired signal vector through a sigmoid activation function so that a polynomial perceptron equalizer is realized. The comparative computational complexity calculations and performance results of the proposed decision feedback equalizer are also provided. 相似文献
2.
A Simple and useful decision feedback equalizer used for non-linear channels with severe linear distortion and mild non-linear distortion is proposed. It is a combination of a nonlinear channel equalizer based on connectionist model and a common decision feedback equalizer for linear channels. For a typical non-linear channel model it is shown that the equalization performances of the proposed equalizer are improved significantly. 相似文献
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本文针对严重线性失真、轻度非线性失真的信道提出了一种简单实用的非线性信道判决反馈均衡器。它是一个将关联模型非线性信道均衡器与线性信道判决反馈均衡器相结合的产物。对典型的非线性信道模型所做的模拟试验表明,该均衡器不仅简单实用、便于实时处理,而且均衡性能得到较大的改善。 相似文献
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《Communications, IEEE Transactions on》1997,45(11):1358-1362
A new approach for the decision feedback equalizer (DFE) based on the functional-link neural network is described. The structure is applied to the problem of adaptive equalization in the presence of intersymbol interference (ISI), additive white Gaussian noise, and co-channel interference (CCI). It is shown through simulation results for a severe amplitude distorted co-channel system that the decision feedback functional-link equalizer (DFFLE) provides significantly superior bit-error rate (BER) performance characteristics compared to the conventional DFE, the linear transversal equalizer (LTE), the nonlinear radial basis function (RBF) neural-network-based structures and the feed-forward functional-link equalizer (FFLE)-based structures. The DFFLE is also shown to have a significantly simpler computational requirement relative to the RBF and the FFLE 相似文献
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A low complexity soft-input soft-output (SISO) block decision feedback equalizer (BDFE) is presented for turbo equalization. The proposed method employs a sub-optimum sequence-based detection, where the soft-output of the equalizer is calculated by evaluating an approximation of the sequence-based a posteriori probability (APP) of the data symbol. The sequence-based APP approximation is enabled by the adoption of both soft a priori information and soft decision feedback, and it leads to better performance and faster convergence compared to symbol-based detection methods as used by most other low complexity equalizers. The performance and convergence property of the proposed algorithm is analyzed by using extrinsic information transfer (EXIT) chart. Both analytical and simulation results show that the new equalizer can achieve a performance similar to that of trellis-based equalization algorithms, with a complexity similar to linear SISO minimum mean square error equalizers. 相似文献
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In this paper,a frequency domain decision feedback equalizer is proposed for single carrier transmission with time-reversal space-time block coding (TR-STBC).It is shown that the diagonal decision feed... 相似文献
7.
Sheng Chen McLaughlin S. Mulgrew B. Grant P.M. 《Communications, IEEE Transactions on》1995,43(5):1937-1946
The paper investigates adaptive equalization of time-dispersive mobile radio fading channels and develops a robust high performance Bayesian decision feedback equalizer (DFE). The characteristics and implementation aspects of this Bayesian DFE are analyzed, and its performance is compared with those of the conventional symbol or fractional spaced DFE and the maximum likelihood sequence estimator (MLSE). In terms of computational complexity, the adaptive Bayesian DFE is slightly more complex than the conventional DFE but is much simpler than the adaptive MLSE. In terms of error rate in symbol detection, the adaptive Bayesian DFE outperforms the conventional DFE dramatically. Moreover, for severely fading multipath channels, the adaptive MLSE exhibits significant degradation from the theoretical optimal performance and becomes inferior to the adaptive Bayesian DFE 相似文献
8.
为克服线性均衡性能的局限性及避免传统判决反馈均衡器的高复杂度,提出了一种判决反馈均衡算法D-MMSE-FE。该均衡器先是分析线性MMSE均衡的结果成分,并根据最小均方误差准则计算出均衡器的前、后向传递函数,形成反馈链路,提高均衡器性能。将该种均衡器应用于TDD-LTE 1×2 SIMO上行链路中,在协议中常用的信道下进行了计算机仿真,仿真结果表明,TDD-LTE 1×2 SIMO均衡器相对于线性均衡器使系统性最多可提高达2 dB。 相似文献
9.
In this paper we introduce a nonlinear equalizer using the Radial Basis Function (RBF) network with decision feedback equalizer (DFE) for electronic dispersion compensation in optical communication systems with on-off-keying and a direct detection receiver. The RBF method introduces a non-linear equalization technique suitable for optical communication direct detection systems that include nonlinear transformation at the photodetector. A bit error rate performance comparison shows that the RBF with DFE out performs the RBF without DFE and achieves similar results provided by maximum likelihood sequence estimator. 相似文献
10.
针对单载波频域均衡系统MMSE均衡器存在残留码间干扰的缺点,提出MMSE-RISIC判决反馈均衡器消除残留码间干扰.MMSE-RISIC均衡器采用传统MMSE均衡后的判决数据,对残留码间干扰进行估计并消除.残留码间干扰的估计主要采用FFT和IFFT运算,与其他方法相比计算量较小.对该均衡器在不同信道下进行了计算机仿真,结果表明,在频率选择性衰落信道条件下,系统性能有了较为明显的提高. 相似文献
11.
This paper investigates the performance of compromise Viterbi algorithm (VA) and standard equalization techniques by computation and simulation over band-limited channels using fourlevel vestigial sideband (VSB) modulation. Linear channel characteristics from the published telephone channel survey were used as examples of band-limited data transmission channels. One of the principal conclusions drawn from the study is that at data rates of 9600 bits/s and less, the linear characteristics of these channels do not limit performance even with linear equalization. It was found that at this data rate, receivers based on linear equalization are very sensitive to timing and carrier phase over some channels. Thus at 9600 bits/s the decision feedback equalizer was found to be a better choice because it is relatively insensitive to carrier phase and timing considerations. Moreover, at 9600 bits/s no problem with error propagation was encountered with the decision feedback equalizer. As the data rate was increased beyond 9600 bits/s the decision feedback tap gains became large enough to cause severe error propagation. The compromise VA receiver structure was effective at higher data rates and was almost unaffected by channel bandwidth up to 12 000 bits/s. 相似文献
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A decision feedback equalizer with time-reversal structure 总被引:1,自引:0,他引:1
This work describes the use of a receiver with a time-reversal structure for low-complexity decision feedback equalization of slowly fading dispersive indoor radio channels. Time-reversal is done by storing each block of received signal samples in a buffer and reversing the sequential order of the signal samples in time prior to equalization. As a result, the equivalent channel impulse response as seen by the equalizer is a time-reverse of the actual channel impulse response. Selective time-reversal operation, therefore, allows a decision feedback equalizer (DFE) with a small number of forward filter taps to perform equally well for both minimum-phase and maximum-phase channel characteristics. The author evaluates the theoretical performance bounds for such a receiver and quantifies the possible performance improvement for discrete multipath channels with Rayleigh fading statistics. Two extreme cases of DFE examples are considered: an infinite-length DFE; and a DFE with a single forward filter tap. Optimum burst and symbol timing recovery is addressed and several practical schemes are suggested. Simulation results are presented. The combined use of equalization and diversity reception is considered 相似文献
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A technique is described for reducing the error propagation resulting from the use of decision feedback equalization in an M-ary, varying system. The technique is applicable when the actual system response varies moderately about a nominal response that can be approximated by a partial response. The decision feedback equalizer (DFE) is supplemented with partial response precoding and detection such that the resulting error propagation is a function of only the difference between the actual system response and the partial response. Simulation results for a system with a nominal response equal to the duobinary partial response are given to illustrate the performance improvement 相似文献
17.
Blind detection of equalization errors in communication systems 总被引:3,自引:0,他引:3
Dogancay K. Kennedy R.A. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1997,43(2):469-482
In adaptive channel equalization, transmitted symbol estimates at the equalizer output may be in error because of excessive channel noise, convergence of the equalizer to a “closed-eye” local minimum, or error propagation if the equalizer has a decision feedback structure. This paper is concerned with the detection of equalization errors (i.e., errors in transmitted symbol estimates) in a blindfolded manner whereby no direct access to the channel input is required. The detection problem is cast into a binary hypothesis testing framework. Assuming a linear communication channel that is time-invariant during the test interval, a relationship between the presence of equalization errors and time variations in the underlying linear model taking the transmitted symbol estimates to the equalizer input is established. Based on this relationship, a uniformly most powerful test is constructed to detect the presence of equalization errors in finite-length observations. Finite sample size and asymptotic detection performance of the test is studied. A method for estimating the equalization delay without direct access to the channel input is developed. The effectiveness of the test is illustrated by way of computer simulations 相似文献
18.
迭代块判决反馈均衡(Iterative Block Decision Feedback Equalization,IBDFE)是单载波频域均衡中一种行之有效的非线性均衡算法,但算法计算复杂度随迭代次数增加而增大。本文针对传统IBDFE算法的不足提出一种基于线性因子更新的频域迭代判决反馈均衡算法,利用了线性因子更新来降低均衡器复杂度,并引入修正因子计算反馈滤波器系数以避免性能损失。仿真结果表明,所提出算法性能与传统IBDFE算法相比复杂度降低且在误比特率为10-5时有0.12 dB的性能增益,与已有的低复杂度算法(Low-Complexity IBDFE,LC-IBDFE)相比有0.1 dB的性能增益。 相似文献
19.
Ali Masoomzadeh-Fard Subbarayan Pasupathy 《International Journal of Wireless Information Networks》1996,3(2):105-115
Indoor radio communication in the 20–60 GHz band using TDMA with differentially encoded QPSK is consideed. A burst-type transmission, based on a basic time slot consisting of a preamble for synchronization and equalizer training and of an information data section, is adopted. We employ fractionally spaced decision feedback equalization and give the relevant analytical and simulated performance results in terms of Doppler frequency. An upper limit is determined for the channel variations which can be tracked by the equalizer. Performance results are obtained for equalization with and without carrier phase recovery. Calculated and simulated probability of error show that error propagation degrades the performance by about 6 dB at a bit error rate of 10–3 for a channel without any diversity. However, the effect of past decision errors is negligible for dual diversity. Numerical stability, required accuracy, and hardware complexity are also discussed. 相似文献
20.
Describes a low-complexity equalization technique for improving the reliability of portable radio links in the presence of multipath time delay spread. A technique that operates on hard-limited received signals, with only the phase information available, is presented. Suboptimum receivers based on a maximum likelihood estimation criterion are discussed, including a sequence estimator and a decision feedback phase detector. A low-complexity adaptive phase equalizer structure using decision-directed phase tracking is proposed. The equalizer does not require the multiplication operations required in most conventional equalization algorithms. The author also proposes a receiver that includes a time-reversal structure and a joint estimator for optimum timing recovery and equalizer training. The time-reversal structure plays a crucial role in maximizing the compensation capability of the phase equalizer. The combined use of phase equalization and diversity reception is also considered 相似文献