Spectral Sidelobe Decaying Property of Walsh-Hadamard Code in MC-CDMA Systems

Lin, Chia-Ching; Chen, Wei-Chang

doi:10.1109/twc.2011.081611.102086

Cited by 8 publications

(3 citation statements)

References 14 publications

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“…It is showed that MC-CDMA can effectively combine all the energy of the received signal in the frequency domain. At the same time, a fast Walsh-Hadamard transform 17,18 can be made for spreading and dispreading in a single sub-channel to improve the computational efficiency of UASNs. Y Jiemin et al 19 propose an MC-CDMA scheme in design of UASNs.…”

Section: Related Workmentioning

confidence: 99%

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Convex optimization–based multi-user detection in underwater acoustic sensor networks

Wang

Zhang

Chen

et al. 2018

International Journal of Distributed Sensor Networks

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Multi-carrier code-division multiple access is an important technical means for high-performance underwater acoustic sensor networks. Nevertheless, severe multiple access interference is a huge challenge. As the core technology, multiuser detection is used to eliminate multiple access interference. The traditional optimal detection algorithms (e.g. maximum likelihood) have very high computational complexity, and the performances of suboptimal detection methods (i.e. zero forcing, minimum mean square error, etc.) are poor. Therefore, taking into account the characteristics of underwater acoustic sensor networks, it is of great significance to design multiuser detection algorithms for achieving a tradeoff between the detection performance and the computational complexity in multi-carrier code-division multiple access systems. In this article, we design a transmitter model of underwater multi-carrier code-division multiple access system and then implement a multiuser detection algorithm based on convex optimization, which is named convex optimization-based algorithm. Next, we conduct the detection performance and computational complexity comparisons of maximum likelihood, zero forcing, minimum mean square error, and convex optimization-based algorithm. The results show that the performance of convex optimization-based algorithm is close to that of maximum likelihood, and the complexity is close to that of zero forcing. Therefore, a tradeoff between the computational complexity and the detection performance is realized in convex optimization-based algorithm. It means that convex optimization-based algorithm is suitable for the multiuser detection in multi-carrier code-division multiple access systems of underwater acoustic sensor networks.

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Section: Related Workmentioning

confidence: 99%

“…Finally, we conduct convex optimization according to equation (17). The convex optimization-based algorithm (COBA) mainly includes initialization, solving the semi-definite problem, implementing Cholesky decomposition, 47,48 and achieving convex optimization in four steps.…”

Section: Convex Optimization-based Mudmentioning

confidence: 99%

Convex optimization–based multi-user detection in underwater acoustic sensor networks

Wang

Zhang

Chen

et al. 2018

International Journal of Distributed Sensor Networks

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“…As opposed to the spreading of data in the time domain, as in the direct sequence CDMA technique, the spreading of data associated with the subcarriers in MC-CDMA is carried out in the frequency domain. In order to ensure orthogonality among users in the frequency domain, Walsh-Hadamard sequences are often implemented to achieve the spreading [4]. However, a disadvantage of the MC-CDMA system is that it is easily affected by imperfect channel frequency response estimation mismatch [5].…”

Section: Introductionmentioning

confidence: 99%

Blind ICA detection based on second-order cone programming for MC-CDMA systems

Jen

Jou

2014

EURASIP J. Adv. Signal Process.

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The multicarrier code division multiple access (MC-CDMA) technique has received considerable interest for its potential application to future wireless communication systems due to its high data rate. A common problem regarding the blind multiuser detectors used in MC-CDMA systems is that they are extremely sensitive to the complex channel environment. Besides, the perturbation of colored noise may negatively affect the performance of the system. In this paper, a new coherent detection method will be proposed, which utilizes the modified fast independent component analysis (FastICA) algorithm, based on approximate negentropy maximization that is subject to the second-order cone programming (SOCP) constraint. The aim of the proposed coherent detection is to provide robustness against small-to-medium channel estimation mismatch (CEM) that may arise from channel frequency response estimation error in the MC-CDMA system, which is modulated by downlink binary phase-shift keying (BPSK) under colored noise. Noncoherent demodulation schemes are preferable to coherent demodulation schemes, as the latter are difficult to implement over time-varying fading channels. Differential phase-shift keying (DPSK) is therefore the natural choice for an alternative modulation scheme. Furthermore, the new blind differential SOCP-based ICA (SOCP-ICA) detection without channel estimation and compensation will be proposed to combat Doppler spread caused by time-varying fading channels in the DPSK-modulated MC-CDMA system under colored noise. In this paper, numerical simulations are used to illustrate the robustness of the proposed blind coherent SOCP-ICA detector against small-to-medium CEM and to emphasize the advantage of the blind differential SOCP-ICA detector in overcoming Doppler spread.

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BER performance analysis of a MC-DS-CDMA wireless communication system with rake receiver employing MRC under Nakagami — m fading

Tasneem

Majumder

2016

2016 3rd International Conference on Electrical Engineering and Information Communication Technology (ICEEICT)

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Spectral Sidelobe Decaying Property of Walsh-Hadamard Code in MC-CDMA Systems

Cited by 8 publications

References 14 publications

Convex optimization–based multi-user detection in underwater acoustic sensor networks

Convex optimization–based multi-user detection in underwater acoustic sensor networks

Blind ICA detection based on second-order cone programming for MC-CDMA systems

BER performance analysis of a MC-DS-CDMA wireless communication system with rake receiver employing MRC under Nakagami — m fading

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