Multiuser detection for multiple-access communications using wavelet-packet transforms

Wang, X.F.; Lu, Wu-Sheng; Antoniou, A.

doi:10.1109/pacrim.1997.620336

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…The key challenge of the detection technique is to estimate the exact data of the specific user from the composite signal. In this connection, the early CDMA-based systems used a traditional detector called a matched filter [72][73][74]. This detector provides the optimum results only if the signature waveforms for the distinct users are orthogonal to the desired user code.…”

Section: Multi-user Detection Techniquesmentioning

confidence: 99%

Doubly Orthogonal Wavelet Packets for Multi-Users Indoor Visible Light Communication Systems

et al. 2019

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Visible Light Communication (VLC) is a data communication technology that modulates the intensity of the light to transmit the information mostly by means of Light Emitting Diodes (LEDs). The data rate is mainly throttled by the limited bandwidth of the LEDs. To combat, Multi-carrier Code Division Multiple Access (MC-CDMA) is a favorable technique for achieving higher data rates along with reduced Inter-Symbol Interference (ISI) and easy access to multi-users at the cost of slightly reduced compromised spectral efficiency and Multiple Access Interference (MAI). In this article, a multi-user VLC system is designed using a Discrete Wavelet Transform (DWT) that eradicates the use of cyclic prefix due to the good orthogonality and time-frequency localization properties of wavelets. Moreover, the design also comprises suitable signature codes, which are generated by employing double orthogonality depending upon Walsh codes and Wavelet Packets. The proposed multi-user system is simulated in MATLAB software and its overall performance is assessed using line-of-sight (LoS) and non-line-of-sight (NLoS) configurations. Furthermore, two sub-optimum multi-users detection schemes such as zero forcing (ZF) and minimum-mean-square-error (MMSE) are also used at the receiver. The simulated results illustrate that the doubly orthogonal signature waveform-based DWT-MC-CDMA with MMSE detection scheme outperforms the Walsh code-based multi-user system. Keywords: visible light communication (VLC); LED; photo-diode (PD); line-of-sight (LoS); non-line-of-sight (NLoS); multi-carrier code division multiple access (MC-CDMA); discrete wavelet transform (DWT); doubly orthogonal wavelet packets (DOWP); multiple access interference (MAI); minimum-mean-square-error (MMSE) IntroductionWith unprecedented demand for high-speed multi-media mobile services, optimization of wireless communication systems has become critical. Due to the limited range of frequencies, radio-frequency (RF) technology is unable to fulfill the needs for the current demands of mobile users [1]. As we are advancing towards 5G, the necessity for the evolution in broadband communication technologies has grown to its peak. The 5G communication networks have already defined performance requirements in which high-speed data delivery (expected to be 10 Gbps) and low latency (less than 1 ms) are the key performance parameters [2]. Visible Light Communication (VLC) is a completely new paradigm that is going to revolutionize the next generation of wireless communication by making use of a visible

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Section: Multi-user Detection Techniquesmentioning

confidence: 99%

Doubly Orthogonal Wavelet Packets for Multi-Users Indoor Visible Light Communication Systems

et al. 2019

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“…Several testimonies of this can be found in the literature [3] following the work initiated by Learned [4]. It should be emphasized, however, that the above studies rely strongly on the assumption that the system is synchronous.…”

Section: Introductionmentioning

confidence: 88%

Wavelet-packet-based signatures for asynchronous CDMA systems

Monera-Llorca

Lu²,

Bhargava³

1999 IEEE Pacific Rim Conference on Communications, Computers and Signal Processing (PACRIM 1999). Conference Proceedings (Cat.

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A wavelet-packet-based family of user signatures for asynchronous CDMA systems is investigated. These signatures are of non-binary nature and are generated by the ap-. plication of the inverse wavelet packet transform. Through numerical optimization, we obtain the wavelet filter which minimizes the crosscorrelation among signatures for different user configuration systems. The improvement in performance is especially notable in the oversaturated system scenario. Finally, we comment briefly on the topics of bandwidth efficiency, user privacy, and implementation.

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Wavelet Packets in Wideband Multiuser Communications

Fan¹

2004

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REPORT DOCUMENTATION PAGEForm Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. 12b. DISTRIBUTION CODE ABSTRACT (Maximum 200 Words)Throughout the entire duration of this contract, the contractor has accomplished a number of tasks. First, we modeled communications channels using wavelet packets, for both time-invariant and time-varying channels. We then developed doubly orthogonal CDMA user spreading waveforms based on wavelet packets. We have also developed and evaluated a wavelet packet based multicarrier CDMA wireless communication system. In this system design a set of wavelet packets are used as the modulation waveforms in a multicarrier CDMA system. The need for cyclic prefix is eliminated in the system design due to the good orthogonality and time-frequency localization properties of the wavelet packets. Two new detection algorithms are developed to work in either time domain or wavelet packet domain to combat multiuser and inter symbol interferences. Compared with the existing DFT based multicarrier CDMA systems, better performance is achieved with the wavelet packet based system by utilizing the saved cyclic prefix overhead for error correction coding. Theoretical analyses as well as computer simulations are performed to support these claims.

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Multiuser detection for multiple-access communications using wavelet-packet transforms

Cited by 3 publications

References 8 publications

Doubly Orthogonal Wavelet Packets for Multi-Users Indoor Visible Light Communication Systems

Doubly Orthogonal Wavelet Packets for Multi-Users Indoor Visible Light Communication Systems

Wavelet-packet-based signatures for asynchronous CDMA systems

Wavelet Packets in Wideband Multiuser Communications

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