This paper presents a Parallelized multilevel Fast Multipole (MLFMA) Moment Method (MoM) code for analyzing the scattering and radiation from electrically large complex bodies modeled by Non-Uniform Rational B-Spline ...
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This paper presents a Parallelized multilevel Fast Multipole (MLFMA) Moment Method (MoM) code for analyzing the scattering and radiation from electrically large complex bodies modeled by Non-Uniform Rational B-Spline Surfaces (NURBS). The bodies are represented by NURBS surfaces which are discretized without remeshing the original geometry. The basis and testing functions are defined and conformed to the exact representation of the geometry. This code has been parallelized using Message Passing Interface (MPI) and it has been successfully applied to the study of large bodies including complex and periodic multilayer structures where the real size and shape are very important.
At the physical layer of wireless vehicular networks, coded cooperation is a possible way of realizing uplink transmit diversity at the mobile vehicles equipped with single antenna. In this work, in order to increase ...
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ISBN:
(纸本)9781424417223;9781424417216
At the physical layer of wireless vehicular networks, coded cooperation is a possible way of realizing uplink transmit diversity at the mobile vehicles equipped with single antenna. In this work, in order to increase the power and bandwidth efficiency, a multilevel coded cooperative system using orthogonal signalling is proposed. Orthogonal signalling not only enables transmission of both users data in single channel symbol but also provides independent detection at the receiver. We investigate the performance of the system by derivation of pairwise and bit error probabilities together with Monte-Carlo simulations.
This paper proposes an adaptive coding (AC) scheme for multilevel bit-interleaved coded modulation (ML-BICM) with minimum mean-square error (MMSE) turbo equalization in frequency-selective multiple-input-multiple-outp...
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This paper proposes an adaptive coding (AC) scheme for multilevel bit-interleaved coded modulation (ML-BICM) with minimum mean-square error (MMSE) turbo equalization in frequency-selective multiple-input-multiple-output (MIMO) channels.. The aim of this paper is to minimize the information rate loss due to the mismatch between channel realization and channel coding. With the aid of the knowledge about extrinsic information transfer characteristics at the receiver, code parameters such as code rates and/or generator polynomials are adaptively selected independently for each ML-BICM layer. Model-based simulation results show that an achievable average throughput can be significantly improved with the proposed AC technique over automatic repeat request with fixed coding rate. Furthermore, the advantageous points of the proposed scheme are verified through field-measurement-data-based simulations.
In wireless networks, coded cooperation is a way of realizing uplink transmit diversity at the mobile user with single antenna. In this work, in order to increase the power and bandwidth efficiency, a multilevel coded...
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In wireless networks, coded cooperation is a way of realizing uplink transmit diversity at the mobile user with single antenna. In this work, in order to increase the power and bandwidth efficiency, a multilevel coded cooperative system using orthogonal signalling is proposed. Orthogonal signalling not only enables transmission of both users data in single channel symbol but also provides independent detection at the receiver. We investigate the performance of the system by derivation of pairwise and bit error probabilities together with Monte-Carlo simulations.
The application of powerful coding for transmission over multiple-input/multiple-output channels is discussed. The authors emphasize that as an immediate consequence. of the mutual information chain rule, multilevel c...
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The application of powerful coding for transmission over multiple-input/multiple-output channels is discussed. The authors emphasize that as an immediate consequence. of the mutual information chain rule, multilevel coding (MLC) constitutes the optimum coded modulation scheme. On the other hand, simple bit-interleaved coded modulation (BICM) is only a convenient alternative for the case of two transmit and one receive antennas when combined with orthogonal space-time block codes. Starting from MLC, the authors further propose a hybrid coded modulation scheme, which favorably combines the advantages of MLC and BICM.
In this paper, multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK) is introduced and its bit error performance in multiple input multiple output (MIMO) facling channels are investigated conside...
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In this paper, multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK) is introduced and its bit error performance in multiple input multiple output (MIMO) facling channels are investigated considering a blind maximum likelihood channel estimation. multilevel turbo coded signals with continuous phase modulation (CPM) provides low spectral occupancy and is Suitable for power and bandwidth-limited channels. Besides, antenna diversity is one of the best method to combat with multipath fading effects. The performance of 2LTC for 4-ary CPFSK over AWGN, Rician (for Rician channel parameter K = 10 dB) and Rayleigh channels are given for 1Tx-1 Rx, 2Tx-1 Rx and 2Tx-2Rx antenna configurations. Channel capacities of 2LTC- 4CPFSK signals are obtained as -5.26, -7.65 and -7.14dB for ITx-1 Rx, 2Tx-1 Rx and 2Tx-2Rx antenna configurations, respectively. Baum-Welch (BW) algorithm is used to estimate the channel parameters. Bit error probabilities of 2 level turbo coded 4 CPFSK (2LTC-4CPFSK) are drawn in the cases of no channel state information (CSI), BW estimation, and perfect CSI. Approximately 0.1 and 0.75 dB gains in E.,INO are obtained using BW channel estimator for Rician and Rayleigh channels, respectively. Therefore, MLTC-CPFSK with BW channel estimator has excellent performance in MIMO fading channels. Copyright (c) 2006 John Wiley & Sons, Ltd.
In this paper, we propose a combined iterative detection and decoding technique that is capable of achieving the maximum diversity of order N-T x L x N-R over single-carrier multiple-input-multiple-output (MIMO) frequ...
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In this paper, we propose a combined iterative detection and decoding technique that is capable of achieving the maximum diversity of order N-T x L x N-R over single-carrier multiple-input-multiple-output (MIMO) frequency-selective Rayleigh fading channels, where NT and NR denote the number of transmit and receive antennas, respectively, and L is the number of multipath components. The so-called spacetime weighted-nonbinary-repeat-accumulate (ST-WNRA) codes are considered in our paper due to their ability to provide a full transmit antenna diversity and their relatively simple encoding and decoding algorithms. Multipath diversity is obtained using a joint-over-antenna turbo-equalization technique based on the minimum-mean-square-error filtering with soft interference cancellation. Computer simulations demonstrate that our proposed turbo-equalized system with ST-WNRA codes is capable of achieving the maximum diversity order with a relatively short codeword length and that the multiuser performance approaches the single-user bound so far as the number of users is smaller than or equal to the number of receive antennas in multiuser MIMO setups. We will also show that by modifying our proposed scheme to an equivalent multilevel coded system, higher bandwidth efficiency can be achieved at the expense of a performance loss while the system still retains the maximum diversity benefit.
By examining the achievable rates of a multistage decoding system on stationary ergodic channels, we derive lower bounds on the mutual information rate corresponding to independent and uniformly distributed (i.u.d.) i...
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By examining the achievable rates of a multistage decoding system on stationary ergodic channels, we derive lower bounds on the mutual information rate corresponding to independent and uniformly distributed (i.u.d.) inputs, also referred to as the i.u.d. information rate. For binary intersymbol interference (ISI) channels, we show that these bounds become tight as the number of decoding stages increases. Our analysis, which focuses on the marginal conditional output densities at each stage of decoding, provides an information rate corresponding to each stage. These rates underlie the design of multilevel coding schemes , based upon low-density parity-check (LDPC) codes and message passing, that in combination with multistage decoding approach the i.u.d. information rate for binary ISI channels. We give example constructions for channel models that have been commonly used in magnetic recording. These examples demonstrate that the technique is very effective even for a small number of decoding stages.
The future Internet traffic growth will require deployment of optical transmission systems with bit rates higher than rate of currently available 40-Gb/s systems, such as 100-Gb/s and above. However, at data rates bey...
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ISBN:
(纸本)9780819469342
The future Internet traffic growth will require deployment of optical transmission systems with bit rates higher than rate of currently available 40-Gb/s systems, such as 100-Gb/s and above. However, at data rates beyond 100-Gb/s the signal quality is significantly degraded mainly due to impact of polarization mode dispersion (PMD), and intra-channel nonlinear effects. All electrically time-division multiplexed (ETDM) multiplexers and de-multiplexers operating at similar to 100-Gb/s are becoming commercially available. However, the modulators operating similar to 100-Gb/s are not widely available so that alternative approaches to enable 100-Gb/s transmission and beyond using commercially available components operating at 40-Gb/s are of high practical importance. In this invited paper, several joint coded-modulation and multiplexing schemes enabling beyond 100-Gb/s transmission using commercially available components operating at 40-Gb/s are presented. Using this approach, modulation, coding and multiplexing are performed in a unified fashion so that, effectively, the transmission, signal processing, detection and decoding are done at much lower symbol rates, where dealing with the nonlinear effects and PMD is more manageable, while the aggregate data rate is maintained above 100-Gb/s. The main elements of our approach include: (i) bit-interleaved LDPC-coded modulation, (ii) multilevel coding (MLC) with LPDC component codes, and (iii) LDPC-coded orthogonal frequency division multiplexing (OFDM). The modulation formats of interest in this paper are M-ary quadrature-amplitude modulation (QAM) and Mary phase-shift keying (PSK), where M=2,...,16, both combined with either Gray or natural mapping rule. It will be shown that coherent detection schemes significantly outperform direct detection ones and provide an additional margin that can be used either for longer transmission distances or for application in an all-optical networks.
In this paper, we address some performance issues of multiple input multiple output (MIMO) channels with a nulling and cancellation (N/C) detector, which is based on the QR factorization. We find a theoretical bit err...
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In this paper, we address some performance issues of multiple input multiple output (MIMO) channels with a nulling and cancellation (N/C) detector, which is based on the QR factorization. We find a theoretical bit error rate (BER). With this, an optimization for the bit energy allocation across multiple transmitter antennas has been considered with the proposed optimization criterion. In addition, the concept of multilevel coding has been adopted for optimizing the performance of a multistage receiver with the N/C detector when a channel code is employed. Through simulations, the performance has been compared for coded signals. Both the code rate and energy optimization across layers are shown to be effective means for improving the performance of MIMO systems when the multistage receiver is employed. In addition, it has been shown that the optimization of code rate for each layer is more effective means than that of bit energy.
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