Performance of a Multiple Access Orthogonal Wavelet Division Multiplexing System

Liew, B.A.; Berber, Stevan; Sandhu, G.S.

doi:10.1109/icita.2005.213

Cited by 8 publications

(8 citation statements)

References 5 publications

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“…These basis signals can be pseudorandom sequences with good orthogonal characteristics and Walsh functions [1], wavelets [2], or chaotic sequences [3,4]. These basis signals can be pseudorandom sequences with good orthogonal characteristics and Walsh functions [1], wavelets [2], or chaotic sequences [3,4].…”

Section: Introductionmentioning

confidence: 99%

Noise‐based spreading in code division multiple access systems for secure communications

Berber

2014

Int J Communication

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Binary spreading sequences or chaotic nonbinary sequences are used in code division multiple access systems. In contrast to those sequences, this paper presents the theory, simulation, and implementation in digital signal processor technology of a code division multiple access system that uses random spreading sequences. The expressions for probability of bit error are derived for the cases when the additive white Gaussian noise and fading are present in the channel. Because the overall transmitted signal is a sum of random signals, the security of signal transmission in this communication system can be enormously increased and will depend on the goodness of the random sequence generator. The developed theory was confirmed by a prototype of the system that was designed in digital signal processor technology. The prototype used spreading sequences that had statistical characteristics very close to the characteristics of theoretical random sequences. The main problem in the system is how to synchronize the received spread sequence with the locally generated sequence. Hence, a mathematical model of the synchronization block for the system has been separately designed and developed. The synchronization procedure has been demonstrated on the basis of application of a periodically repeated pilot sequence. erates a multiuser signal that has characteristics of a white Gaussian noise signal because the spreading is performed using Gaussian random number generator. The system is supposed to have the best possible masking property of the transmitted information contents and the best possible protection of information contents, which depends mostly on the random characteristics of spreading sequences.In practice, it is hard to design a pure random number generator. In order to confirm our theoretical model, we generated Gaussian sequences in the digital signal processor (DSP) prototype by using the random sequences generated by nonlinear feedback shift registers and then transforming them using the Box-Muller method [12]. For this purpose, a prototype of the complete CDMA communication system is developed including noise and fading generators by using TigerSHARC Analog Devices processor as a hardware platform.The theoretical model of the system is developed for the case when the transmitter generates a multiuser signal, composed of N single-user random noise-like signals. The expression for the probability of error is derived, and the characteristics of the system are analyzed, assuming that additive white Gaussian noise (AWGN) and fading are present in the channel [19,20]. A CDMA system with impulse noise in the channel and diversity reception is presented in [21]. The uplink system is analyzed assuming a wide-band multipath channel represented by the delay tapped lines [22].In this system, the received CDMA signal is a mixture of Gaussian sequences, which increases security in signal transmission because it is hard to distinguish and separate message signals from the channel noise. The noise-like random nature of the trans...

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Section: Introductionmentioning

confidence: 99%

Noise‐based spreading in code division multiple access systems for secure communications

Berber

2014

Int J Communication

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“…Traditionally, signal spreading and user information encoding in direct sequence CDMA reverse and forward links have been based on application of short and long pseudo random sequences with good orthogonal characteristics, Walsh functions or wavelets [1,2,3]. In spite of the fact these sequences are semi-deterministic they spread signals in frequency domain and thus increase security in signal transmission and enhance resistance to jamming.…”

Section: Introductionmentioning

confidence: 99%

“…The characteristics of CDMA systems extremely deteriorate in the presence of fading [1,2,6]. Due to the problem of sequence synchronization, as addressed in [7,8] for conventional systems, the influence of fading is expected to be even higher in systems with chaotic and noise-like spread sequences.…”

Section: Introductionmentioning

confidence: 99%

Reverse CDMA link based on noise-like spreading sequences and fading mitigation

Berber

Zhan

2009

Proceedings of the 2009 International Conference on Wireless Communications and Mobile Computing: Connecting the World Wireless

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This paper presents a theoretical model of a reverse CDMA link that uses noise-like spreading sequences in the case when AWGN and flat fading are present in the channel. It is known fact that the fading can be mitigated by the use of a block interleaver/deinterleaver structure. However, how to mitigate fading in a CDMA link that uses noise-like spreading sequences is not investigated and reported yet. For the proposed model, the expressions for the probability of error are derived and compared with the previously derived expression for the system that uses binary and non-binary chaotic sequences. It was shown that the degradation in the BER performances of the CDMA system in the presence of fading can be reduced applying interleaver/deinterleaver blocks to be close to the level of AWGN influence.Theory. KeywordsNoise based CDMA, probability of error derivation, non-binary spreading sequences, noise-like sequences.

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“…Analyzing the approaches described in [5][6][7][8][9] gives insight about the extensive research performed on the various solution approaches to problems of LTE OFDMA systems and provides proof that orthogonal wavelets are a better and viable alternative to the existing wireless systems. Although the analysis and evaluations were done for BER and PAPR, it lacks in a unified system implementation, resource analysis, and thorough performance evaluation for current LTE systems.…”

Section: Key Contributionsmentioning

confidence: 99%

“…Raajan et al [7] provided bit error rate (BER) performance graphs for all the wavelets and modulation schemes, but no hardware architecture was provided for the proposed system. Similarly, Tao et al [8] and Liew et al [9] analyzed orthogonal wavelet division multiplexing (OWDM) for signaling over wideband linear time-varying channels (LTV) but, again, did not provide any architecture for deployment. 1-D orthogonal wavelets have been used [10][11][12][13][14] for image processing applications.…”

Section: Introductionmentioning

confidence: 99%

An orthogonal wavelet division multiple-access processor architecture for LTE-advanced wireless/radio-over-fiber systems over heterogeneous networks

Mahapatra

Leung

Stouraitis

2014

EURASIP J. Adv. Signal Process.

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The increase in internet traffic, number of users, and availability of mobile devices poses a challenge to wireless technologies. In long-term evolution (LTE) advanced system, heterogeneous networks (HetNet) using centralized coordinated multipoint (CoMP) transmitting radio over optical fibers (LTE A-ROF) have provided a feasible way of satisfying user demands. In this paper, an orthogonal wavelet division multiple-access (OWDMA) processor architecture is proposed, which is shown to be better suited to LTE advanced systems as compared to orthogonal frequency division multiple access (OFDMA) as in LTE systems 3GPP rel.8 (3GPP, http://www.3gpp.org/DynaReport/36300.htm). ROF systems are a viable alternative to satisfy large data demands; hence, the performance in ROF systems is also evaluated. To validate the architecture, the circuit is designed and synthesized on a Xilinx vertex-6 field-programmable gate array (FPGA). The synthesis results show that the circuit performs with a clock period as short as 7.036 ns (i.e., a maximum clock frequency of 142.13 MHz) for transform size of 512. A pipelined version of the architecture reduces the power consumption by approximately 89%. We compare our architecture with similar available architectures for resource utilization and timing and provide performance comparison with OFDMA systems for various quality metrics of communication systems. The OWDMA architecture is found to perform better than OFDMA for bit error rate (BER) performance versus signal-to-noise ratio (SNR) in wireless channel as well as ROF media. It also gives higher throughput and mitigates the bad effect of peak-to-average-power ratio (PAPR).

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Performance of a Multiple Access Orthogonal Wavelet Division Multiplexing System

Cited by 8 publications

References 5 publications

Noise‐based spreading in code division multiple access systems for secure communications

Noise‐based spreading in code division multiple access systems for secure communications

Reverse CDMA link based on noise-like spreading sequences and fading mitigation

An orthogonal wavelet division multiple-access processor architecture for LTE-advanced wireless/radio-over-fiber systems over heterogeneous networks

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