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BER Performance (ber + performance)
Selected AbstractsOn the effects of interpolator window shape and symbol location on the BER of diversity PSAM 16-QAMEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2007Lingzhi Cao We consider pilot symbol assisted modulation (PSAM) implemented with a sinc interpolator. The sensitivity of the error rate performance to different window functions applied to the sinc interpolator is investigated. The bit error rates (BERs) for diversity M -ary quadrature amplitude modulation (MQAM) with different window functions applied to the sinc interpolator are compared. The Kaiser window is found superior to the other windows considered. A thorough discussion of the dependency of the BER performance on the symbol location is also given. Copyright © 2007 John Wiley & Sons, Ltd. [source] The application of modified lapped transform domain median filter to narrow,band interference excision in DSSS systemsEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2001Chongni Li Guangruihu A novel communication receiver which uses lapped transform (LT) incorporating modified median filter (MMF) algorithm is designed for narrow,band interference (NB1) excision. Comparing to traditional Fourier Transform, LT has longer basis vectors, less spectral leakage, thus better frequency resolution. The LT domain MMF algorithm takes full advantages of the direct sequence spread spectrum signal, as well as the characteristics of LT, performs the transform domain filtering twice. The first filtering locates the position of interference and mitigates most of them. The second filtering was performed in a small neighborhood of the located interference. So LT domain MMF algorithm can completely mitigate the interference without distorting the desired signal. Simulation results demonstrated the improved BER performance and increased robustness of our approach. [source] Kalman filter-based channel estimation and ICI suppression for high-mobility OFDM systemsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2008Prerana Gupta Abstract The use of orthogonal frequency division multiplexing (OFDM) in frequency-selective fading environments has been well explored. However, OFDM is more prone to time-selective fading compared with single-carrier systems. Rapid time variations destroy the subcarrier orthogonality and introduce inter-carrier interference (ICI). Besides this, obtaining reliable channel estimates for receiver equalization is a non-trivial task in rapidly fading systems. Our work addresses the problem of channel estimation and ICI suppression by viewing the system as a state-space model. The Kalman filter is employed to estimate the channel; this is followed by a time-domain ICI mitigation filter that maximizes the signal-to-interference plus noise ratio (SINR) at the receiver. This method is seen to provide good estimation performance apart from significant SINR gain with low training overhead. Suitable bounds on the performance of the system are described; bit error rate (BER) performance over a time-invariant Rayleigh fading channel serves as the lower bound, whereas BER performance over a doubly selective system with ICI as the dominant impairment provides the upper bound. Copyright © 2008 John Wiley & Sons, Ltd. [source] A multi-user CDMA receiver utilizing decorrelating detector with additional dummy pilot responseINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2003Mitsuhiro Tomita Abstract A pilot assisted CDMA system which uses extended spreading sequences with guard sequences under a quasi-synchronous condition is capable of separating the interference components included in the input of a de-correlating receiver by solving a system of linear equations. The performance of such a system, however, depends on the property of the de-correlating matrix consisting of the received pilots, which correspond to the respective user spreading sequences and the multi-path channel conditions. That is, the regularity of the matrix often tends to degrade, and the rank reduces occasionally primarily due to the multi-paths, resulting in solutions that are vulnerable to AWGN. The present paper proposes an effective technique to solve this problem by introducing a virtual user into a group of real users that are to be served. The simulation results indicate a remarkable improvement in the bit-error-rate (BER) performance. In addition, based on the BER performance, the system has a RAKE-like function that has power-sum characteristics. Copyright © 2003 John Wiley & Sons, Ltd. [source] Adaptive predistortion of COFDM signals for a mobile satellite channelINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2003Nibaldo Rodriguez Abstract In this paper, we consider the optimization of the performance of QPSK and 16-QAM coded orthogonal frequency division multiplexing (COFDM) signals over the non-linear and mobile satellite channel. A high power amplifier and Rician flat fading channel produces non-linear and linear distortions; an adaptive predistortion technique combined with turbo codes will reduce both types of distortion. The predistorter is based on a feedforward neural network, with the coefficients being derived using an extended Kalman filter (EKF). The conventional turbo code is used to mitigate Rician flat fading distortion and Gaussian noise. The performance over a non-linear satellite channel indicates that QPSK COFDM followed by a predistorter provides a gain of about 1.7 dB at a BER of 3×10,3 when compared to QPSK COFDM without the predistortion scheme and 16-QAM COFDM provides a gain of 0.5 dB output back-off and 1.2 dB signal to noise ratio at a BER of 3×10,5 when compared with an adaptive predistorter based on the Harmmerstein model. We also investigate the influence of the guard time interval and Doppler frequency effect on the BER performance. When the guard interval increases from 0 to 0.125T samples and the normalized Doppler frequency is 0.001, there is a gain of 0.7 and 1 dB signal to noise ratio at a BER of 6×10,4 for QPSK and 16-QAM COFDM, respectively. Copyright © 2003 John Wiley & Sons, Ltd. [source] Bandwidth-efficient turbo coding over Rayleigh fading channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2002Stéphane Y. Le Goff Abstract Introduced in 1993, turbo codes can achieve high coding gains close to the Shannon limit. In order to design power and bandwidth-efficient coding schemes, several approaches have been introduced to combine high coding rate turbo codes with multilevel modulations. The coding systems thus obtained have been shown to display near-capacity performance over additive white Gaussian noise (AWGN) channels. For communications over fading channels requiring large coding gain and high bandwidth efficiency, it is also interesting to study bit error rate (BER) performance of turbo codes combined with high order rectangular QAM modulations. To this end, we investigate, in this paper, error performance of several bandwidth-efficient schemes designed using the bit-interleaved coded modulation approach that has proven potentially very attractive when powerful codes, such as turbo codes, are employed. The structure of these coding schemes, termed ,bit-interleaved turbo-coded modulations' (BITCMs), is presented in a detailed manner and their BER performance is investigated for spectral efficiencies ranging from 2 to 7 bit/s/Hz. Computer simulation results indicate that BITCMs can achieve near-capacity performance over Rayleigh fading channels, for all spectral efficiencies considered throughout the paper. It is also shown that the combination of turbo coding and rectangular QAM modulation with Gray mapping constitutes inherently a very powerful association, since coding and modulation functions are both optimized for operation in the same signal-to-noise ratio region. This means that no BER improvement is obtainable by employing any other signal constellation in place of the rectangular ones. Finally, the actual influence of the interleaving and mapping functions on error performance of BITCM schemes is discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Performance of a turbo-coded CDMA system in a mobile satellite channelINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 4 2005Jin Young Kim Abstract The bit error rate (BER) performance of a turbo-coded code-division multiple-access (CDMA) system operating in a satellite channel is analysed and simulated. The system performance is compared for various constituent decoders, including maximum a posteriori probability (MAP) and Max-Log-MAP algorithms, and the soft-output Viterbi algorithm. The simulation results indicate that the Max-Log-MAP algorithm is the most promising among these three algorithms in overall terms of performance and complexity. It is also shown that, for fixed code rate, the BER performance is improved substantially by increasing the number of iterations in the turbo decoder, or by increasing the interleaver length in the turbo encoder. The results in this paper are of interest in CDMA-based satellite communications applications. Copyright © 2005 John Wiley & Sons, Ltd. [source] W-band physical layer design issues in the context of the DAVID,DCE experiment,INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2004Claudio Sacchi Abstract This paper aims at focusing on the aspects concerning the physical layer design for an innovative satellite communication experiment. Such an experiment, denoted by the acronym DAVID,DCE (Data and Video Interactive Distribution,Data Collection Experiment) is based on the exploitation of the W-band (75,110 GHz) for high-bit-rate satellite transmission. The potential advantages of using of the W-band are mainly related to the great bandwidth availability, and to the absence of interference. Moreover, an expected result of the experiment is a substantive improvement in the communication system's performances in the presence of meteorological phenomena (e.g. rain) as compared with the more conventional Ka-band satellite transmission. On the other hand, problems to be faced concern the non-ideal behaviours of hardware devices employed for high-frequency digital transmission. In particular, carrier recovery and timing recovery are the most crucial signal-processing tasks to be carefully considered in the design of the physical level of the system, because they considerably suffer from hardware impairments. The purpose of this work is to illustrate the proposed solutions in terms of the most critical modulation, demodulation and synchronization design issues, together with the effects of non-ideal behaviours of hardware components on BER performances. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||