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Received Signal (received + signal)
Selected AbstractsParallel interference cancellation in DS-CDMA optical networks using bias compensationEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2009A. Okassa-M'foubat A receiver based on the parallel cancellation of multiple access interference by bias compensation is considered here for a direct sequence unipolar optical code division multiple access (DS-OCDMA) system. It relies on the estimation of interferences from undesired users, the regeneration of interfering signals at the output of first canceller stage and their substraction from the received signal after amplification by a bias compensation factor in the second stage. The performance of such a technique is analysed in a synchronous network using orthogonal optical codes and the results are compared with those for different types of conventional receivers. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fuzzy-based multiuser detector for impulsive CDMA channelEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 7 2007Adel M. Hmidat A new fuzzy multiuser detector for non-Gaussian synchronous direct sequence code division multiple access (DS-CDMA) is proposed for jointly mitigating the effects of impulsive noise and multiple access interference (MAI). The proposed scheme combines a linear decorrelator and antenna array with a nonlinear preprocessor based on fuzzy logic and rank ordering. The fuzzy rule is incorporated to combat impulsive noise by eliminating outliers from the received signal. The performance of the proposed scheme is assessed by Monte Carlo simulations and the obtained results demonstrate that the proposed fuzzy detector outperforms other reported schemes in terms of bit error rate (BER) and channel capacity. Copyright © 2007 John Wiley & Sons, Ltd. [source] Array antenna assisted doppler spread compensator for OFDMEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2002Minoru Okada This paper proposes a novel array-antenna-assisted Doppler spread compensator for orthogonal frequency division multiplexing (OFDM), which is sensitive to fast time-variation of the radio propagation channel. In the proposed compensator, a linear array antenna is installed on top of the vehicle. The compensator estimates the received signal at a certain point on the linear array antenna by using space domain interpolation. Because the relative position of the estimated receiving point with respect to the ground does not change during the effective symbol duration of an OFDM signal, the time variation due to the movement of the vehicle can be compensated for. Computer simulation shows that the compensator can compensate for the bit error rate performance degradation due to time-variation of the channel when the velocity of the vehicle is up to 180km/h and a two-element array antenna is used at the carrier frequency of 600 MHz. The bit error rate performance can be further improved by using a four-element array antenna. [source] Blind decoder-assisted interference reduction for coded DS-CDMA systems,INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 9 2005Ryan A. Pacheco Abstract We propose an iterative blind interference reduction strategy for short-burst coded DS-CDMA systems. The blind strategy works by creating a set of ,training sequences' in the receiver that are used as input to an interference reduction algorithm whose task is to produce a corresponding set of equalizers that attempt to recover the desired signal. To maintain a reasonable complexity level we develop a semi-blind interference reduction algorithm that is capable of equalizing the received signal with a relatively small training sequence length (thus maintaining a small training sequence set). The objective then becomes to determine which equalizer from the generated set gives the best performance (smallest bit error). It is demonstrated that the success of this scheme depends greatly on the ability to find an appropriate criterion for picking the best equalizer. Of the tested criteria, one based on feedback from the decoder (essentially using trellis information) is shown to achieve nearly optimal performance. Copyright © 2005 John Wiley & Sons, Ltd. [source] Sensitivity improvement of the receiver module in the passive tag-based RFID readerINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 11 2009Jonghun Chun Abstract In this paper, we have designed an RFID reader receiver system for improving the performance of the passive Tag-based 908.5,914,MHz RFID reader, and analyzed the system performance vis-à-vis frequency, reader, and tag properties. The commercial receiver system causes a loss in sensitivity because of its 24 capacitors and six inductors. To improve the overall sensitivity of the receiver, we have designed a system using a circulator, low noise amplifier (LNA) and a SAW filter. The experimental results show that the use of a circulator to separate the Tx/Rx paths eliminates interference, the LNA improves the sensitivity of the Rx module and SAW filter eliminates the noise and spurious components in the received signal. Copyright © 2009 John Wiley & Sons, Ltd. [source] A multipath interference cancellation technique for WCDMA downlink receiversINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2007Derong Liu Abstract In this paper, we present a simple interference cancellation technique for the downlink of wideband code-division multiple-access (WCDMA) systems in multipath environment. With the same knowledge required by a RAKE receiver, the present method acts as an equalizer and cancels the interfering multipath signals from the received signal to retrieve the orthogonality property of the received signal. The present receiver has a simple structure and it has significant performance gain against the RAKE receiver. In addition, the noise enhancement is negligible when there is a line of sight path or the channel power delay profile has an exponential decaying form. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effect of noisy carrier reference signal and interference on performance of MSK receiverINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2004Mihajlo C. Stefanovic Abstract This paper considers the coherent detection of minimum shift keying signal and a degradation in error rate performance from ideal due to an interference and a phase discrepancy between the carrier of the received signal and the carrier of the receiver. The error rate is calculated for the simple receiver model with integrate-and-dump circuits. The reference carrier signal unsteadiness is presented by the probability density function of the first order non-linear PLL phase error, while the uncertainty due to an interference is involved in the system model with a random phase of cosine signal that accompanied the useful signal. Copyright © 2004 John Wiley & Sons, Ltd. [source] Five-port receiver with improved sensitivityMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008Fernando Rangel de Sousa Abstract This article reports the architecture of a five-port receiver without vector base circuit generators in which three antennas provide three phase-shifted copies of the received signal. A 2.4-GHz prototype was implemented for concept proofing, and the measurements point to a sensitivity improvement of 6 dB with respect to comparable classic five-port receivers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2945,2947, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23858 [source] Signal enhancement in multiuser communication through adaptivity on transmitMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2003Abdellatif Medouri Abstract This paper presents a technique to enhance the received signals in a multiuser communication environment through the use of adaptivity on transmit. This technique is based on the principle of reciprocity and is independent of the material medium of transmission and the near-field environments. The objective here is to select a set of weights to be applied to each transmitting antenna, which is a function of the user location. The methodology is not a function of the multipath environment. Furthermore, the transmitted signal may be directed to a particular receiver location and simultaneously be minimized at other receiver locations while operating on the same frequency. Numerical simulations have been made to illustrate the novelty of the proposed approach. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 265,269, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11034 [source] | ||||||||||