共查询到18条相似文献,搜索用时 109 毫秒
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一种低复杂度的Turbo多用户检测技术 总被引:3,自引:0,他引:3
基于Turbo原理,提出了一种适合于同步DS-CDMA系统的迭代多用户接收机结构,它通过在反复迭代的软输入出多用户检测器和一组信道译码之间获得连续的软判决,从而得到一种低复杂度的多用户检测算法-软MMSE干扰消除。 相似文献
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同步CDMA系统中的迭代多用户检测技术 总被引:2,自引:1,他引:1
迭代多用户检测技术是Turbo译码算法中的精髓“迭代思想”的又一个应用 ,它结合了turbo码的译码和多用户检测的研究 ,成为目前通信领域研究的热点。结果表明 ,多次迭代后 ,系统性能将得到很大提高 ,接近单用户的性能。 相似文献
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WuLili HuangHui LiaoGuisheng 《电子科学学刊(英文版)》2003,20(4):289-292
In this letter, the detection of asynchronous DS-CDMA signal with multipath fading and interference from neighboring cells is studied. A novel multiuser detector based on Gibbs sampler is proposed, in which Gibbs sampler is employed to perform the Bayesian multiuser detection according to the linear group-blind decorrelator output. Since Gibbs sampler is dependent of parameter estimation that can be improved by the output of the detector, an enhanced Gibbs sampier based detector using the improved parameter estimation is put forward. The novel multiuser detection technique has the advantages of high performance and wide applications. Computer simulations show its effectiveness. 相似文献
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Kopbayashi M. Boutros J. Caire G. 《Selected Areas in Communications, IEEE Journal on》2001,19(8):1450-1460
We derive a low-complexity receiver scheme for joint multiuser decoding and parameter estimation of code division multiple access signals. The resulting receiver processes the users serially and iteratively and makes use of soft-in soft-out single-user decoders, of soft interference cancellation and of expectation-maximization parameter estimation as the main building blocks. Computer simulations show that the proposed receiver achieves near single-user performance at very high channel load (number of users per chip) and outperforms conventional schemes with similar complexity 相似文献
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We propose a novel scheme for iterative multiuser detection and turbo decoding. The multiuser detector and single-user turbo decoders are coupled such that after each turbo decoding iteration the extrinsic information of the interfering users is passed to the multiuser detector, and after each multiuser iteration, updated a posteriori probabilities are passed to the single-user turbo decoders as the soft input metrics. In synchronous systems, the proposed detector approaches the multiuser capacity limit within 1 dB in the low signal-to-noise ratio region 相似文献
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Turbo greedy multiuser detection 总被引:4,自引:0,他引:4
AlRustamani A.A. Damnjanovic A.D. Vojcic B.R. 《Selected Areas in Communications, IEEE Journal on》2001,19(8):1638-1645
Previously, a novel scheme for iterative multiuser detection and turbo decoding was proposed by Damnjanovic and Vojcic (2000, 2001). In this scheme, multiuser detection and single-user turbo decoding are tightly coupled to maximize the overall gain. The extrinsic probabilities for the coded bits of the interfering users, obtained after each turbo decoding iteration, are used as a priori probabilities in the following multiuser iteration and the extrinsic information for the systematic bits of the desired user is used as a priori information in the next single-user turbo decoding iteration. Turbo decoding of parallel concatenated convolutional codes is carried out in parallel fashion. It has been shown that the proposed detector approaches the multiuser capacity limit within 1 dB in the low signal-to-noise ratio region. However, the main drawback of the scheme is its exponential complexity in the number of users, which is due to the complexity of the maximum a posteriori probability (MAP) multiuser detector. In this paper, we show that the complexity of the scheme can be significantly reduced by replacing the (MAP) multiuser detector with an iterative detector derived from the greedy multiuser detector proposed by AlRustamani and Vojcic (2000). In this paper, we demonstrate that, for both the additive white Gaussian noise and the frequency-nonselective Rayleigh fading, the substantial reduction in complexity of the iterative scheme proposed by Damnjanovic and Vojcic when the greedy detector is utilized introduces a slight degradation in performance 相似文献
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We develop an iterative multiuser receiver for decoding turbo-coded synchronous code-division multiple-access signals in both Gaussian and non-Gaussian noise. A soft-input soft-output nonlinear multiuser detector is combined with a set of single-user channel decoders in an iterative detection/decoding structure. The nonlinear multiuser detector utilizes the prior probabilities of each user's bits to form soft estimates used for multiple-access interference cancellation. The channel decoders perform turbo-code decoding and produce posterior probabilities which are fed back to the multiuser detector for use as prior probabilities. Simulation results show that the proposed multiuser receiver performs well in both Gaussian and non-Gaussian noise. In particular, single-user turbo-code performance can be approached within a few iterations with medium to low cross correlation (ρ⩽0.5) 相似文献
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A practically interesting approach for iterative channel estimation, multiuser detection, and single-user decoding based on maximum a posteriori symbol-by-symbol estimation for direct sequence/code-division multiple-access (DS-CDMA) is proposed. The receiver relies on the output of a bank of matched filters for each user and each path, and combines interference cancellation with iterated soft-decision feedback to improve channel estimation accuracy and data symbol reliability in course of a few iterations. We show that in this way, near single-user channel phase and amplitude estimation accuracy is achieved for frequency-selective fading channels, even in highly loaded systems, and illustrate that reliable data symbol estimation can be performed. 相似文献
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We consider joint source-channel and multiuser decoding for frequency selective Rayleigh fading code-division multiple-access channels. The block source-channel encoder is defined by a vector quantizer. We investigate optimal (minimum mean-square error) decoding and “user-separated” decoding of lower complexity. The studied decoders are soft in the sense that they utilize all soft information available at the receiver. Simulations indicate significant performance gains of the introduced decoders compared with a tandem approach that uses maximum-likelihood multiuser detection plus table-lookup decoding 相似文献
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An approach to optimal soft decoding for vector quantization (VQ) over a code-division multiple-access (CDMA) channel is presented. The decoder of the system is soft in the sense that the unquantized outputs of the matched filters are utilized directly for decoding (no decisions are taken), and optimal according to the minimum mean-squared error (MMSE) criterion. The derived decoder utilizes a priori source information and knowledge of the channel characteristics to combat channel noise and multiuser interference in an optimal fashion. Hadamard transform representations for the user VQs are employed in the derivation and for the implementation of the decoder. The advantages of this approach are emphasized. Suboptimal versions of the optimal decoder are also considered. Simulations show the soft decoders to outperform decoding based on maximum-likelihood (ML) multiuser detection. Furthermore, the suboptimal versions are demonstrated to perform close to the optimal, at a significantly lower complexity in the number of users. The introduced decoders are, moreover, shown to exhibit near-far resistance. Simulations also demonstrate that combined source-channel encoding, with joint source-channel and multiuser decoding, can significantly outperform a tandem source-channel coding scheme employing multiuser detection plus table lookup source decoding 相似文献