Large Set of CI Spreading Codes for High-Capacity MC-CDMA

Natarajan, Balasubramaniam; Wu, Zhiqiang; Nassar, C.R.; Shattil, S.

doi:10.1109/tcomm.2004.836564

Cited by 46 publications

(31 citation statements)

References 8 publications

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“…In [52][53][54], the use of MC-CDMA with novel carrier interferometry (CI) complex spreading codes was proposed. The carrier interferometry MC-CDMA (CI/MC-CDMA) method, applied to cognitive radio systems, offers enhanced performance and flexibility compared to conventional MC-CDMA with WH spreading codes.…”

Section: Ci/mc-cdmamentioning

confidence: 99%

Multicarrier Spread Spectrum Modulation Schemes and Efficient FFT Algorithms for Cognitive Radio Systems

Sundararajan

Govindaswamy

2014

Electronics

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Spread spectrum (SS) and multicarrier modulation (MCM) techniques are recognized as potential candidates for the design of underlay and interweave cognitive radio (CR) systems, respectively. Direct Sequence Code Division Multiple Access (DS-CDMA) is a spread spectrum technique generally used in underlay CR systems. Orthogonal Frequency Division Multiplexing (OFDM) is the basic MCM technique, primarily used in interweave CR systems. There are other MCM schemes derived from OFDM technique, like Non-Contiguous OFDM, Spread OFDM, and OFDM-OQAM, which are more suitable for CR systems. Multicarrier Spread Spectrum Modulation (MCSSM) schemes like MC-CDMA, MC-DS-CDMA and SS-MC-CDMA, combine DS-CDMA and OFDM techniques in order to improve the CR system performance and adaptability. This article gives a detailed survey of the various spread spectrum and multicarrier modulation schemes proposed in the literature. Fast Fourier Transform (FFT) plays a vital role in all the multicarrier modulation techniques. The FFT part of the modem can be used for spectrum sensing. The performance of the FFT operator plays a crucial role in the overall performance of the system. Since the cognitive radio is an adaptive system, the FFT operator must also be adaptive for various input/output values, in order to save energy and time taken for execution. This article also includes the various efficient FFT algorithms proposed in the literature, which are suitable for CR systems.

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Section: Ci/mc-cdmamentioning

confidence: 99%

Multicarrier Spread Spectrum Modulation Schemes and Efficient FFT Algorithms for Cognitive Radio Systems

Sundararajan

Govindaswamy

2014

Electronics

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“…(2) A set of code patterns called carrier interferometry (CI) 66 codes have been developed for application in CDMA communication. Proposed SS watermarking algorithms may be extended for the purpose using carrier interferometry (CI) spreading codes rather than using the binary-valued code patterns.…”

Section: Conclusion and Scope Of Future Workmentioning

confidence: 99%

Performance Improvement in Spread Spectrum Image Watermarking Using Wavelets

Maity

Kundu

2011

Int. J. Wavelets Multiresolut Inf. Process.

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This paper investigates the scope of wavelets for performance improvement in spread spectrum image watermarking. Performance of a digital image watermarking algorithm, in general, is determined by the visual invisibility of the hidden data (imperceptibility), reliability in the detection of the hidden information after various common and deliberate signal processing operations (robustness) applied on the watermarked signals and the amount of data to be hidden (payload) without affecting the imperceptibility and robustness properties. In this paper, we propose a few spread spectrum (SS) image watermarking schemes using discrete wavelet transform (DWT), biorthogonal DWT and M -band wavelets coupled with various modulation, multiplexing and signaling techniques. The performance of the watermarking methods are also reported along with the relative merits and demerits.

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“…In SS modulation, particularly in CDMA, many orthogonal (or near orthogonal) spreading codes, like pseudo noise (PN) codes, gold codes, Walsh codes, Kashimi codes [19], and carrier interferometry codes [20,21] have been studied for capacity improvement. The watermarked signal can be written as…”

Section: Multicarrier Ss Watermarkingmentioning

confidence: 99%

Multicarrier spread spectrum watermarking for secure error concealment in fading channel

Maity

Maity²,

Sil

2010

Telecommun Syst

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This paper proposes a novel multicarrier spread spectrum (SS) watermarking scheme for the application of image error concealment using multicarrier-code division multiple access (MC-CDMA) with binary phase shift keying (BPSK) transmission in Rayleigh fading channel. The goal is achieved by embedding important information (image digest) which is extracted from the original image itself, and is used to introduce sufficient redundancy in the transmitted image. Half-toning technique is applied to obtain image digest from its low-resolution version. At the decoder side, data demodulation as well as watermark decoding are done using minimum mean square error combining (MM-SEC) strategy. The extracted image digest is used to correct the damaged regions. The integration of SS watermarking with the existing SS modulation not only simplifies the design but also offers significant performance improvement for error concealment in fading channel. Authorized users having the knowledge of code patterns for SS watermarking can only perform the error concealment operation and the method is secured. Experimental results duly support the effectiveness of the proposed scheme.

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Large Set of CI Spreading Codes for High-Capacity MC-CDMA

Cited by 46 publications

References 8 publications

Multicarrier Spread Spectrum Modulation Schemes and Efficient FFT Algorithms for Cognitive Radio Systems

Multicarrier Spread Spectrum Modulation Schemes and Efficient FFT Algorithms for Cognitive Radio Systems

Performance Improvement in Spread Spectrum Image Watermarking Using Wavelets

Multicarrier spread spectrum watermarking for secure error concealment in fading channel

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