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International Conference on Signal Processing Proceedings (ICSP)

作者： J. Lehtomaki J. Vartiainen Telecommunication Laboratory University of Oulu Finland

Generating signature sequences using operators of the discrete periodic wavelet transform is demonstrated. A new application of a fast optimal receiver algorithm for synchronous orthogonal code division multiple access augmented with time division multiple access (OCDMA/TDMA) is shown. Finally, a novel method to generate signature sequences with low residual noise using a cosine modulated filter bank (CMBF) structure is presented.

关键词： Time division multiple access Discrete wavelet transforms Wavelet packets Multiaccess communication Laboratories Noise generators Filter bank direct-sequence code-division multiple access Finite impulse response filter Autocorrelation

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New quadriphase Jacket sequence for perfect zero cross correlation

New quadriphase Jacket sequence for perfect zero cross corre...

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IEEE International Symposium on Spread Spectrum Techniques and Applications

作者： Chen Xinhao RanRong MoonHo Lee Institute of Electronic and Information South-Central University for Communities China Institute of Information & Communication Chonbuk National University Korea

ISBN: (纸本)0780376277

We propose a method to construct quadriphase perfect zero cross correlation (ZCC) sequences generalized from Kronecker product given sequences and rows of Jacket matrices, they are able to completely reject the interuser interferences. Furthermore a simple sequence generator is designed based on the shift register for the proposed sequences that can be easily applied to a multiuser mobile communication CDMA system.

关键词： Multiaccess communication Mobile communication Interference Shift registers direct-sequence code-division multiple access Modulation coding Throughput Frequency diversity Receiving antennas Receivers

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Outage probability, throughput and delay analysis of cellular DS-CDMA system in the presence of correlated signal and interference

Outage probability, throughput and delay analysis of cellula...

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IEEE Asia-Pacific Conference on Circuits and Systems

作者： W. Rattanakoch C. Kimpan Ouen Pin-ngern S. Noppanakeepong Engineering and Research Center for Communications and Information Technology ReCCIT King Mongkut's Institute of Technology Thailand Shinawatra University Bangkok Thailand

In this paper, we evaluate the performance of a cellular DS-CDMA system, by taking into account the correlation between signal and interference, to determined outage probability, throughput and delay for the reverse link with power control error. The numerical results show that when the correlation is considered the outage probability decreased, the throughput value increased, that is, the performance can be achieved.

关键词： Throughput Delay Signal analysis Multiaccess communication Interference Random variables Power control direct-sequence code-division multiple access Quality of service Radio link

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Analysis of beamformer configurations for DS-CDMA systems

Analysis of beamformer configurations for DS-CDMA systems

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IEEE Conference on Vehicular Technology (VTC)

作者： N.Y. Wang P. Agathoklis A. Antoniou Department of Electrical and Computer Engineering University of Victoria Victoria BC Canada

Two different beamformer configurations for the base station receiver in direct-sequence code-division multiple access (DS-CDMA) systems, namely, a chip-based and a symbol-based configuration, are studied. In the chip-based configuration, different interfering components are rejected based on the spatial distribution of their power. In the symbol-based configuration, spatial diversity is exploited after despreading and different interfering components are rejected based on their interfering strength, which depends on both their power and code correlation with the signal of interest. Thus, for the symbol-based configuration, more effort is applied to rejecting the interfering components with higher interfering strength and thus a more selective and efficient system is achieved. Detailed performance analysis and simulations show that in the presence of multiple-access interference, the symbol-based configuration can lead to a significant improvement in the signal-to-interference-plus-noise ratio relative to that achieved with the chip-based configuration for both asynchronous and synchronous DS-CDMA systems.

关键词： Multiaccess communication Array signal processing Performance analysis Analytical models Matched filters Receiving antennas direct-sequence code-division multiple access Diversity reception multiple access interference System performance

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Centralized adaptive MMSE detectors for multirate DS-CDMA in multipath fading channels

Centralized adaptive MMSE detectors for multirate DS-CDMA in...

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National Conference on Radio Science (NSRC)

作者： M. El-Khamy S. Elnoubi O.A. Alim Department of Electrical Engineering Alexandria University Egypt Department of Electrical Engineering Alexandria University

Future mobile systems will support services with different data rates. In this paper, we propose centralized feed-forward feedback architectures for adaptive minimum mean square error (MMSE) detectors for asynchronous multirate direct sequence code division multiple access (DS-CDMA) systems. A multipath Rayleigh fading channel is assumed. The MMSE detector is implemented using the recursive least squares (RLS) algorithm. We compare between the different. proposed architectures and the results are verified using simulations.

关键词： Detectors Multiaccess communication Fading Filters Video recording Feedforward systems Computer architecture direct-sequence code-division multiple access Multimedia systems Facsimile

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Blind multiuser receiver for space-time coded CDMA signals in frequency-selective channels

Blind multiuser receiver for space-time coded CDMA signals i...

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Asilomar Conference on Signals, Systems & Computers

作者： Jinghong Ma J.K. Tugnait Aubum University Auburn AL USA

Blind detection of a desired user's signal in a direct sequence code division multiple access (DS-CDMA) system using multiple transmit and receive antennas and space-time (ST) block coding is considered. We consider Alamouti's ST coding scheme for two transmit antennas designed for flat-fading channels, but allow the channel to be frequency-selective. Past work on blind detectors for ST-coded DS-CDMA systems is restricted to flat-fading channels. A (spreading) code-constrained inverse filter criterion (IFC)-based linear blind detector to detect a desired user's signal for uncoded CDMA signals exploiting only a single transmit and single receive antenna was recently presented by Tugnait and Li. In ST-coded multi antenna CDMA systems, a user signal may be treated as the superposition of several virtual user signals derived from the same parent user. In this paper a novel approach combining the code-constrained IFC and a penalty function is developed to simultaneously extract all virtual users associated. with a given ST-coded user. Global minima of the proposed cost functions are analyzed.

关键词： Multiaccess communication Receiving antennas Block codes Transmitting antennas Detectors Frequency conversion direct-sequence code-division multiple access Nonlinear filters Data mining Cost function

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A spectral method for periodic estimation of the PN sequences in lower SNR DS-CDMA signals

A spectral method for periodic estimation of the PN sequence...

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International Conference on Communications, Circuits and Systems (ICCCAS)

作者： Chang Tianqi Zhou Zhengzhong Institute of Communication and Information Engineering UEST Chengdu China

We propose a new method based on the reprocessing of the power spectral density of direct sequence code division multiple access (DS-CDMA) signals, it can solve the difficult problem of periodic detection and estimation of the PN sequence in DS-CDMA signals. The results of computer simulation show that these methods can work well on the lower signal-to-noise ratio (SNR) input signals.

关键词： Multiaccess communication direct-sequence code-division multiple access Signal to noise ratio Interference Demodulation Additive white noise Computer simulation Spread spectrum communication Resists Multiuser detection

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Underwater acoustic receiver employing direct-sequence spread spectrum and spatial diversity combining for shallow-water multiaccess networking

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IEEE JOURNAL OF OCEANIC ENGINEERING 2001年第4期26卷 594-603页

作者： Tsimenidis, CC Hinton, OR Adams, AE Sharif, BS Univ Newcastle Upon Tyne Dept Elect & Elect Engn Underwater Res Grp Newcastle Upon Tyne NE1 7RU Tyne & Wear England

This paper proposes an underwater adaptive-array receiver structure that utilizes direct-sequence code division multiple access and spatial diversity combining in order to achieve reliable low-data rate multiuser communication in an asynchronous shallow-water network. The performance of the proposed receiver architecture has been verified by means of offline processing of data acquired during sea trials in the summer of 1999 in the North Sea. Results show that this computationally efficient structure is near-far resistant and provides successful multiuser operation in the shallow-water channel.

关键词： direct-sequence code-division multiple access spread spectrum shallow-water networking

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CDMA functional blocks using recycling integrator correlators - Matched filters and delay-locked loops

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 2001年第3期36卷 385-397页

作者： Iizuka, K Miyamoto, M Ohta, Y Suyama, T Hara, K Kawama, S Matsui, H Azuma, S Taguchi, S Fujimoto, Y Senderowicz, D Sharp Corp Nara 6328567 Japan SynchroDesign Inc Berkeley CA 94704 USA

The recycling integrator correlator (RIC) is a novel approach for implementing correlators that consumes less power than conventional digital or analog CMOS correlators, The RIC modulates the product of a received signal and a pseudorandom noise (PN) sequence into a bit stream by first-order Delta Sigma modulation. The accumulated number represents the quantized correlation value. Using RICs, two functional blocks of a direct sequence code division multiple access (DS-CDMA) demodulator targeting IMT-2000, a matched filter (MF) and a delay locked-loop (DLL) are implemented in silicon. In the fabricated 256-tap QPSK MF-RIC, two 256-tap double-sampling MFs sample the I and Q received analog signals at a rate of 8 Msample/s, Their outputs are 9-bit quantized correlation values with a 256-chip PN sequence at the same rate as the sampling rate. The DLL-RIC can adapt to spreading ratios from 32 to 256 with the use of an auxiliary ADC that can compensate the degradation of dynamic range when the spreading ratio is small. Processed in a 0.35-mum CMOS process, the MF-RIC and the DLL-RIC, respectively, occupy 22.8 and 2.28 mm(2) and dissipate 23.0 and 3.4 mW at 2-V power supply.

关键词： ADC CMOS analog integrated circuit correlator delay-locked loop delta-sigma modulation direct-sequence code-division multiple access matched filter strobed comparator telescopic cascode amp W-CDMA

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Hybrid ARQ and optimal signal-to-interference ratio assignment for high-quality data transmission in DS-CDMA

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 2001年第1期12卷 19-29页

作者： Sun, SS Krzymien, WA Conexant Syst Inc Wireless Commun Div Irving TX USA Univ Alberta TRLabs Edmonton AB Canada

Combined error correction and detection techniques, or hybrid automatic-repeat-request (ARQ) schemes with negative acknowledgment are considered for highly reliable reverse link data transmission in direct sequence code division multiple access (DS-CDMA) personal communication systems. The proposed selective repeat hybrid ARQ scheme employs an inner convolutional code for error correction and an outer shortened BCH code for error detection. Each negative acknowledgment message contains all packet sequence numbers that have been detected in error, and it is both error-correction and error-detection encoded. Accepted packet error rate and throughput are derived as a function of the error correction encoded frame error rate. An optimum signal-to-interference ratio (SIR) assignment maximizing the system's capacity is also found. A comprehensive simulation is conducted to evaluate performance of the data transmission system. Analysis and simulations show that by applying the proposed type I hybrid ARQ scheme with properly selected system parameters, virtually error free and highly efficient data transmission in CDMA personal communication systems is possible.

关键词： direct-sequence code-division multiple access Automatic repeat request error correction Signal to interference ratio Error analysis data transmission Bit error rate Personal communication systems COMMUNICATION SYSTEMS inspection technique HARQ Error detection

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