In this paper, the applicability of the subspace-based blind adaptive algorithm in multiple access ultra-wideband systems is investigated. However, in the multiuser transmission environment, multiple access interferen...
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In this paper, the applicability of the subspace-based blind adaptive algorithm in multiple access ultra-wideband systems is investigated. However, in the multiuser transmission environment, multiple access interference becomes a serious issue and results in the degradation of system performance. In order to overcome this shortcoming, we propose a novel and low complexity decision mechanism, termed the decision timing instant (DTI). A major advantage of the DTI algorithm is that it admits an adaptive implementation with low computational complexity instead of singular value decomposition. In the present paper, we exploit the joint blind multiuser detection in UWB systems, a combined scheme is proposed, which couples the minimum-mean-square-error and the DTI subspace tracking algorithm under UWB time-variant channels. Simulation results show that DTI is able to fast and precisely trace the variation of the channel environment and to improve the performance of the blind adaptive multiuser detection with a subspace approach over time-varying channels.
In this paper, we deal with interference suppression in asynchronous direct-sequence code-division multiple-access (CDMA) systems employing binary phase-shift keying modulation. Such an interference may arise from oth...
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In this paper, we deal with interference suppression in asynchronous direct-sequence code-division multiple-access (CDMA) systems employing binary phase-shift keying modulation. Such an interference may arise from other users of the network, from external low-rate systems, as well as from a CDMA network coexisting with the primary network to form a dual-rate network. We derive, for all of these cases, a new family of minimummean-square-error detectors, which differ from their conventional counterparts in that they minimize a modified cost function. Since the resulting structure is not implementable with acceptable complexity, we also propose some suboptimum systems. The statistical analysis reveals that both the optimum and the suboptimum receivers are near-far resistant, not only with respect to the other users, but also with respect to the external interference. We also present a blind and a recursive least squares-based, decision-directed implementation of the receivers wherein only the signature and the timing of the user to be decoded and the signaling time and the frequency offset of the external interferer are assumed known. Finally;computer simulations show that the proposed adaptive algorithm outperforms the classical decision-directed RLS algorithm.
In this article, we investigate the performance of a coded multiple-input multiple-output (MIMO) multi-carrier (MC) system in underwater communication, where acoustic interference and ambient noise are the two major c...
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In this article, we investigate the performance of a coded multiple-input multiple-output (MIMO) multi-carrier (MC) system in underwater communication, where acoustic interference and ambient noise are the two major channel impairments. The channel model considered in this work is based on the shallow water model that has eleven paths. In our work, the acoustic signal is spread with the aid of a high rate spreading sequence to alleviate the effects of acoustic interference. At the receiver, non-linear detectors based on Zero-Forcing (ZF) and minimum-mean-square-error (MMSE) are employed for signal detection. The simulation results reveal that the system under consideration with the MMSE detector provides better performance in terms of the achievable bit error rate than the system with the ZF detector while achieving higher data rates. (C) 2015 Elsevier Ltd. All rights reserved.
In multi-detection (MD) systems including over-the-horizon radar (OTHR) systems, the forward-based receivers systems and passive coherent location systems, resolvable multiple detections of one target due to the multi...
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In multi-detection (MD) systems including over-the-horizon radar (OTHR) systems, the forward-based receivers systems and passive coherent location systems, resolvable multiple detections of one target due to the multi-path propagation will be received, in which both identification (including measurement association and propagation mode/transmitting origin identification) and estimation (including path-conditional state estimation and multi-path track fusion) are deeply coupled and affect each other. Up to present, all corresponding methods fall into the scope of sequential identification orientated or estimation orientated processing, and hence the solutions are not satisfactory. Here the joint identification and estimation scheme for the MD systems (MD-JIE) is developed based on the generalized Bayes risk considering both identification and estimation performance. The likelihood-ratio function and the conditional probability density function as the identification cost and estimation cost are recursively calculated, respectively. Taking the data-association constraints into consideration, the proposed MD-JIE scheme is implemented via online constrained optimization technology. Compared to the identification-then-estimation (ITE) method and the estimation-then-identification (ETI) method, the proposed MD-JIE method prevails in the joint performance measure with the higher correct identification rate than the ETI method and the smaller root MSE than the ITE method. Besides, the robustness of the proposed method is verified.
Low-complexity adaptive receivers based on smart antennas with post- and pre-despreading structures are presented. Comparisons between three space-time (ST) schemes employing minimum-mean-square-error, a constant modu...
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Low-complexity adaptive receivers based on smart antennas with post- and pre-despreading structures are presented. Comparisons between three space-time (ST) schemes employing minimum-mean-square-error, a constant modulus algorithm, and a decision-directed algorithm for constant modulus signals are investigated in detail.
This presentation proposed an autocorrelation-based signal detection scheme to get a better resulting. The signal detection scheme is combined by Autocorrelation Filter and an improved linear minimummeansquareerror...
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ISBN:
(纸本)9783037851579
This presentation proposed an autocorrelation-based signal detection scheme to get a better resulting. The signal detection scheme is combined by Autocorrelation Filter and an improved linear minimummeansquareerror (MMSE) estimator. The Autocorrelation Filter is used to reject the interference, and the improved linear MMSE estimator is used to get the least error. Both two methods are based on the non-overlapping property of the signals in autocorrelation domain. The theory consequence and Simulation results indicate that this signal detection scheme can achieve a high detection quality.
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