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GA based adaptive receiver for MC-CDMA system

TURKISH JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES 2015年第Sup-1期23卷 2267-2277页

作者： Khan, Muhammad Adnan Umair, Muhammad Choudhry, Muhammad Aamer Saleem Isra Univ Sch Engn & Appl Sci Islamabad Pakistan

multicarrier systems like the multicarrier code division multiple access (MC-CDMA) systems are designed for maximum usability of available bandwidth. We use the MC-CDMA system with Alamouti's space time coding in this paper. We propose the genetic algorithm (GA) in order to calculate MC-CDMA receiver weights with two variation schemes. The proposed schemes reduce receiver complexity. The bit error rate and convergence rate are also improved by increasing the number of genes and chromosomes of the GA in both schemes as compared with conventional LMS based receivers of the MC-CDMA system. This is verified via simulations.

关键词： multiple input and multiple output multicarrier code division multiple access space time block coding genetic algorithm

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Broadband CDMA techniques

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IEEE WIRELESS COMMUNICATIONS 2005年第2期12卷 8-18页

作者： Adachi, F Garg, D Takaoka, S Takeda, K Tohoku Univ Dept Elect & Comp Engn Sendai Miyagi 980 Japan

A very high-speed wireless access of 100 Mb/s to 1 Gb/s is required for fourth-generation mobile communications systems. However, for such high-speed data transmissions, the channel is severely frequency-selective due to the presence of many interfering paths with different time delays. A promising wireless access technique that can overcome the channel frequency-selectivity and even take advantage of this selectivity to improve the transmission performance is CDMA. There may be two approaches in CDMA technique: direct sequence CDMA and multicarrier CDMA. A lot of attention is paid to MC-CDMA. However, recently it has been revealed that DS-CDMA can achieve good performance comparable to MC-CDMA if proper frequency domain equalization is adopted. This article discusses their similarities and performances. A major transmission mode in 4G systems will be packet-based. Automatic repeat request combined with channel coding is a very important technique. Recent research activity on this technique is also introduced.

关键词： Modulation coding Signal processing Wireless communication Broadband communication Multiaccess communication Frequency Mobile communication multicarrier code division multiple access Automatic repeat request Delay effects

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Parallel interference cancellation with different linear equalisation and Rake receiver for the downlink MC-CDMA systems

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IET COMMUNICATIONS 2012年第15期6卷 2351-2360页

作者： Al-fuhaidi, B. A. Hassan, H. E. A. Salah, M. M. Alagooz, S. S. Mil Tech Coll Dept Elect Commun Fac Elect Engn Cairo Egypt

The multi-carrier code division multiple access (MC-CDMA) is becoming a very attractive multiple access technique for high-rate data transmission in the future wireless communication systems. MC-CDMA systems transmitting over multipath channels suffer from inter-symbol interference (ISI) and multiple access interference (MAI). Recently, MC-CDMA with equalisation has attracted much attention for its ability to obtain an excellent performance even in strong frequency-selective fading channels. In this study, the proposed architecture uses the minimum mean-square error (MMSE) with parallel interference cancellation (PIC) for downlink MC-CDMA system and compared with another system based on the rake receiver with PIC for downlink MC-CDMA system. A comparison between such architectures is presented. The effect of the tentative decision functions and the effect of the loading users on the performance of the two proposed receivers are discussed and presented in this study. Simulation results show that the combination of tentative decisions with PIC and equalisation provides an efficient solution to suppress the MAI and ISI in downlink MC-CDMA systems over frequency-selective fading channels.

关键词： Electromagnetic compatibility and interference tentative decision function downlink MC-CDMA system wireless communication system least mean squares methods intersymbol interference fading channels multicarrier code division multiple access code division multiple access multiple access interference high-rate data transmission multipath channel multiple access communication multiple access technique ISI radio receivers Rake receiver PIC MMSE parallel interference cancellation frequency-selective fading channel Interpolation and function approximation (numerical analysis) Radio links and equipment linear equalisation MAI radiofrequency interference minimum mean-square error

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Channel estimation and tracking for MC-CDMA signals

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 2004年第3期15卷 249-258页

作者： Sanguinetti, L Morelli, M Mengali, U Univ Pisa Dept Informat Engn I-56100 Pisa Italy

This paper investigates the impact of channel estimation errors in the uplink and downlink of a multicarrier code-division multiple-access (MC-CDMA) system. Pilot blocks are periodically inserted into the downlink data stream to perform a least-squares channel estimation. It is shown that a single-user minimum-mean-square-error (MMSE) detector endowed with the proposed channel estimator is robust to estimation errors even under full-loaded conditions. In the uplink scenario channel estimates are computed through a least-mean-square algorithm and are passed to a linear multi-user MMSE detector or a parallel interference cancellation (PIC) receiver. Simulations indicate that in this case the system performance depends heavily on the quality of the channel estimates, meaning that they are particularly critical. Copyright (C) 2004 AEI.

关键词： multicarrier code division multiple access System performance up link Error analysis channel estimation tracking Mini Mental State Examination Downlink Least mean square algorithm

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Iterative Message Passing for Pilot-Assisted Multiuser Detection in MC-CDMA Systems

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IEEE TRANSACTIONS ON COMMUNICATIONS 2012年第11期60卷 3353-3364页

作者： Aktas, Emre Hacettepe Univ Dept Elect & Elect Engn TR-06800 Beytepe Turkey

Application of the belief propagation (BP) algorithm is proposed for pilot-assisted reception of multi-carrier code division multiple access systems where the input symbols are binary phase shift keying symbols. The proposed method utilizes a Bayesian network graph that includes channel parameters as explicit nodes representing random variables. Channel parameters in both frequency and time domains are included in the graph. The messages on the graph are obtained by making large system assumptions for the user symbols and Gaussian assumptions for the messages related to the channel parameters. Density evolution analysis is performed whose results match well with the simulation results. For the simulated scenario it is found that BP with the proposed graph outperforms channel estimation followed by graph based detection, and non-graph based iterative channel estimation.

关键词： Iterative algorithms belief propagation channel estimation multiuser detection multicarrier code division multiple access

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Random characteristics of carrier frequency offset and a joint fading branch correlation in an asynchronous multi-carrier coded-division multiple-access system

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IET COMMUNICATIONS 2011年第17期5卷 2551-2557页

作者： Chen, J. I. -Z. Dayeh Univ Dept Elect Engn Dasuen 51505 Changhwa Taiwan

The carrier frequency offset (CFO) is one of the critical parameters for degrading the overall performance of radio systems modulated with a scheme of multiple carriers. The evaluation of system performance for a multi-carrier coded-division multiple-access (MC-CDMA) radio system with CFO effect mentioned previously is investigated in this study. Apart from the aforementioned parameter, the other important parameter referred to as fading branch correlation (FBC) occurring in the propagating channel is rarely applied in the study of MC-CDMA systems' performance. For the sake of simplicity, subcarriers are typically considered independently. However, the randomisation incurred in generating CFO and FBC should be simultaneously considered to calculate the overall performance. The focus of this work is an aggregate investigation to determine which parameter, that is, CFO or FBC, primarily dominates the performance of an MC-CDMA system. Assume that applying the same quantity of CFO (epsilon) and FBC (lambda) in serving the simulation, that is, both values of CFO and FBC are assumed and assigned in the interval of (0.4, 1.0). Moreover, several novel formulas include both CFO and FBC parameters and many three-dimensional curves are presented and illustrated in this article.

关键词： System performance multicarrier code division multiple access Fluidized bed combustion Multi access systems Radio systems carrier frequency offset CDMA mobile communications

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The sensitivity of MC-CDMA to synchronisation errors

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 1999年第4期10卷 429-436页

作者： Steendam, H Moeneclaey, M Univ Ghent DIGCOM Dept Telecommun & Informat Proc B-9000 Ghent Belgium

In this contribution, we investigate the sensitivity of MC-CDMA systems to synchronisation errors. We show that the signal-to-noise ratio (SNR) of the MC-CDMA system at the input of the decision device in the presence of a carrier frequency offset or a clock frequency offset is a rapidly decreasing function of the number of carriers. For a maximal load, carrier phase jitter and timing jitter give rise to a degradation that is independent of the spectral content of the jitter;moreover, the degradation caused by carrier phase jitter is independent of the number of carriers. A constant carrier phase offset and a constant timing offset cause no degradation of the MC-CDMA system performance.

关键词： multicarrier code division multiple access Jitter signal to noise ratios degradation offsets carrier phase timing jitter deterioration carrier frequency offset porters(transport workers) CDMA mobile communications synchronization error

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Smoothed Sparse Blind DOA Estimation for MC-CDMA Systems Based on Tensor Decomposition

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IEEE WIRELESS COMMUNICATIONS LETTERS 2023年第9期12卷 1548-1552页

作者： Wang, Yuexian Liu, Chao Luo, Shuai Liu, Xiangyang Tellambura, Chintha Northwestern Polytech Univ Sch Elect & Informat Xian 710072 Peoples R China Univ Alberta Dept Elect & Comp Engn Edmonton AB T6G 1H9 Canada

We propose a blind direction of arrival (DOA) estimation method for multicarrier code-division multiple access (MC-CDMA) systems, which does not require knowledge of the spreading codes of transmitters. Our method involves reconstructing a fourth-order tensor with observations from the antenna array at the receiver. We then apply higher-order singular value decomposition (HOSVD) to separate the signal subspace from the noise subspace. To enhance the sparsity of the solution, we develop a smoothed l(0)-norm sparse reconstruction method by designing continuous functions with reweighted vectors. Finally, DOA estimates are obtained by searching the spectrum of the sparse solution using an iterative method that ensures fast convergence. Numerical simulations show its superiority over previous work.

关键词： Direction-of-arrival estimation multicarrier code division multiple access codes Tensors Wireless communication Receiving antennas Sparse matrices multicarrier code-division multiple access (MC-CDMA) direction of arrival (DOA) fourth-order tensor higher-order singular value decomposition (HOSVD) smoothed l ₀-norm

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New Mutually Orthogonal Complementary Sets With Non-Power-of-Two Lengths

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IEEE SIGNAL PROCESSING LETTERS 2021年 28卷 359-363页

作者： Tian, Liying Lu, Xiaoshuai Xu, Chengqian Li, Yubo Yanshan Univ Sch Informat Sci & Engn Qinhuangdao 066004 Hebei Peoples R China Hebei Key Lab Informat Transmiss & Signal Proc Qinhuangdao 066004 Hebei Peoples R China

Mutually orthogonal complementary sets (MOCSs) have found a number of practical applications in wireless communications and radar owing to their perfect aperiodic auto-correlation and cross-correlation properties. Recently, toward the challenge of designing MOCSs with non-power-of-two lengths, direct constructions were presented by Wu et al. using generalized Boolean functions (GBFs). In this letter, a new construction of MOCSs is proposed based on GBFs, which leads to MOCSs with flock size 2(k+1) and length 2(m) + 2(t), whose set size is 1/2 of the flock size, where integers 0 <= t < k <= m. In addition, the constructed MOCSs can yield column sequence peak-to-mean envelope power ratio (PMEPR) of at most 2.

关键词： Cascading style sheets Correlation Upper bound multicarrier code division multiple access Boolean functions Wireless communication Technological innovation Generalized Boolean function (GBF) multi carrier code-division multiple-access (MC-CDMA) mutually orthogonal complementary set (MOCS) peak -to-mean envelope power ratio (PMEPR)

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Maximum a posteriori decorrelating receiver for MC-CDMA systems

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 2006年第1期17卷 151-155页

作者： Boujemâa, H Siala, M Ecole Super Commun Tunis El Ghazala 2083 Ariana Tunisia

In this letter, we propose a maximum a posteriori decorrelating receiver (DR) for multicarrier code division multiple access (MC-CDMA) systems. The decorrelating receiver consists in a maximum a posteriori combining of an uncorrelated version of the signal demodulated over the different subcarriers. The DR performance is compared to that of the conventional receiver (CR) which is based on a maximum ratio combining strategy. Copyright (c) 2006 AEIT.

关键词： multicarrier code division multiple access Receivers Maximum a posteriori estimation letter DR CDMA mobile communications

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