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Rotated Constellations for Improved Time and Frequency Diversity in DVB-NGH

IEEE TRANSACTIONS ON BROADCASTING 2013年第2期59卷 298-305页

作者： Gozalvez, David Joan Gimenez, Jordi Gomez-Barquero, David Cardona, Narcis Univ Politecn Valencia Valencia 46022 Spain

In this paper, we investigate the potential gains that can be obtained with rotated constellations in DVB-NGH, the next-generation mobile broadcasting standard. Rotated constellations exploit the concept of signal-space diversity (SSD) to increase the diversity order of bit-interleaved coded modulation (BICM) at the expense of higher demodulation complexity without the need of additional transmission power or bandwidth. Two-dimensional rotated constellations (2DRC) were originally included in DVB-T2 (terrestrial second generation) to improve the reception robustness in fading channels. DVB-NGH inherits the same 2DRC from DVB-T2 and includes four-dimensional rotated constellations (4DRC) for certain configurations. Moreover, the standard has adopted a new component interleaver optimized for the utilization of rotated constellations with long time interleaving (TI) and time-frequency slicing (TFS). In this context, the additional robustness of rotated constellations is very interesting to counter the presence of signal outages in the time and frequency domains. To investigate the potential gains of 2DRC and 4DRC, we employ an information-theoretic approach based on mutual information, as well as physical layer simulations in DVB-NGH systems. The results reveal that rotated constellations are important to increase the diversity gains of long TI and TFS, and also to reduce the zapping time perceived by the users.

关键词： bit-interleaved coded modulation DVB-NGH DVB-T2 rotated constellations time interleaving time-frequency slicing

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Variable LDPC coding rate performances for multicarrier systems using HD decoding

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IEE PROCEEDINGS-COMMUNICATIONS 2006年第1期153卷 69-73页

作者： Cances, JP Meghdadi, V Univ Limoges ENSIL F-87068 Limoges France

An adaptive coding scheme minimising the BER of a bit-interleaved coded modulation OFDM system performing hard-decisions (HD) after the demodulation and ideal interleaving is proposed. The subcarrier code rate levels subject to a rate constraint are varied according to perfect channel state information at the transmitter. The derived adaptive scheme uses low-density parity-check codes. A modified bit-flipping algorithm provides HD decoding and can be applied either alone or combined with a power loading scheme. It is shown by Monte Carlo simulations that, for broadband systems with Rayleigh fading, the loading procedure provides a signal-to-noise ratio gain up to 3dB for in average BER level of 10(-5).

关键词： adaptive coding scheme bit-interleaved coded modulation Game theory channel coding variable rate codes bit error rate BICM parity check codes Monte Carlo simulation modulation coding multicarrier system OFDM modulation broadband system power loading scheme adaptive codes interleaved codes OFDM system low-density parity-check code Monte Carlo methods broadband networks Rayleigh channels decision theory hard-decision decoding error statistics perfect channel state information BER decoding demodulation bit-flipping algorithm Rayleigh fading LDPC transmitter Codes Radio links and equipment orthogonal frequency division multiplexing

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Efficient Variational Bayesian Method for Joint Channel Estimation and Signal Detection in OFDM-Based AF Relay Networks

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IEEE COMMUNICATIONS LETTERS 2015年第10期19卷 1786-1789页

作者： Sadough, Seyed Mohammad Sajad Chamideh, Zahra Shahid Beheshti Univ Fac Elect Engn Dept Telecommun GC Tehran Iran

We propose improved joint channel estimation and data detection in orthogonal frequency division multiplexing (OFDM) amplify-and-forward (AF) relay network in the case of imperfect partial channel knowledge at the destination. To improve the detection accuracy, we adopt the variational Bayesian approximation (VBA) which is an iterative Bayesian method for channel estimation. We derive a modified iterative estimator that takes into account the channel estimation errors at the previous iteration, to reduce the impact of channel uncertainty at the next iteration, and hence, to improve the overall detection accuracy. By comparison with state of the art VBA-based estimators through numerical analysis, we highlight the superiority of our new VBA method and demonstrate a notable improvement in terms of bit error rate and mean square error between the true and the estimated channel.

关键词： Amplify-and-forward OFDM bit-interleaved coded modulation variational Bayesian inference

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Error Floor Estimation of QC-LDPC coded modulation With Importance Sampling

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IEEE COMMUNICATIONS LETTERS 2021年第1期25卷 28-32页

作者： Zhu, Mingyang Jiang, Ming Zhao, Chunming Southeast Univ Natl Mobile Commun Res Lab Nanjing 210096 Peoples R China Purple Mt Labs Nanjing 211111 Peoples R China

This letter presents a low-complexity error floors estimation method for bit-interleaved coded modulation with quasi-cyclic low-density parity-check (LDPC) codes. Using surrogate bit-channels (SBCs) as hypothetic equivalent channels, the importance sampling method based on the stable trapping sets is applied to evaluate the error floors. It is shown that the error floors of bit-interleaved coded modulation systems can be effectively estimated, and the presented method is appropriate for various types of modulators and interleavers.

关键词： bit-interleaved coded modulation LDPC codes error floor importance sampling surrogate channels

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Semi-blind channel estimation using the EM algorithm in iterative MIMO APP detectors

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第11期5卷 3165-3173页

作者： Khalighi, Mohammad-Ali Boutros, Joseph Jean Ecole Natl Super Telecommun Bretagne F-75013 Paris France

We consider channel estimation in multiple-input multiple-output (MIMO) systems using iterative detection at the receiver. Space-time bit-interleaved coded modulation. (BICM) and soft-input soft-output maximum a posteriori (MAP) symbol detection and decoding are considered. Channel coefficients are updated at each iteration of the detector using a semi-blind estimation approach based on the expectation maximization (EM) algorithm. We first show that a "classical" and non-optimized EM implementation, as already proposed in some previous works, gives a biased estimate of the channel coefficients. We then try to optimize the EM implementation and propose a modification to it that provides an unbiased channel estimate and leads to a better convergence of the iterative detector. We show that considerable improvement in the receiver performance can be obtained by using our proposed modified unbiased (MU) FM algorithm, especially for large number of transmit antennas and short training sequences. We also show that when MIMO signal detection is strongly asymmetric in the sense of too few receive antennas, the EM-based channel estimation may be of little interest. Moreover, we consider a simple semi-blind estimation scheme, based on hard decisions on reliable decoded data bits, and compare its performance with the EM based estimation methods.

关键词： MIMO systems channel estimation semi-blind estimation training sequences expectation maximization bit-interleaved coded modulation iterative detection

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A Secure coded MIMO System Under Imperfect Channel Estimation

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2024年第12期73卷 18834-18845页

作者： Son, Thara Lee, Hyein Kim, Sooyoung Jeonbuk Natl Univ IT Convergence Res Ctr Div Elect Engn Jeonju 561756 South Korea

There have been many researches on physical layer security (PLS) schemes using dynamic channel information, but most of them assumed the perfect channel information, which is difficult to obtain in practical systems. This paper proposes an efficient PLS scheme for coded multi-input multi-output (MIMO) systems operating under imperfect channel estimation conditions. Since coded MIMO systems are typically equipped with an interleaver for bit-interleaved coded modulation (BICM), which is associated with soft iterative decoding, the scheme proposed herein adopts a random interleaving index, which is a function of the legitimate channel. This scheme also includes a novel strategy to prevent the performance degradation caused by channel estimation error through the combination of ancillary forward error correction (AFEC). This innovative concept can archive an advanced level of security protection without requiring any additional power. We also derive the secrecy rate of the proposed scheme. The simulation results presented in this paper demonstrate that the proposed scheme effectively protects the transmitted data without any information leakage to the eavesdropper.

关键词： Indexes Security MIMO communication Channel estimation Vectors Iterative decoding Forward error correction bit-interleaved coded modulation channel estimation error forward error correction multi-input-multi-output physical layer security

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Link Resource Adaptation for Multiantenna bit-interleaved coded Multicarrier Systems

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2012年第7期60卷 3644-3656页

作者： Stupia, Ivan Lottici, Vincenzo Giannetti, Filippo Vandendorpe, Luc Catholic Univ Louvain B-1348 Louvain Belgium Univ Pisa Dept Informat Engn I-56122 Pisa Italy

The availability of flexible radio interfaces capable of adapting their configuration to the time-varying operating environment is the key response to the demand encountered in modern wireless networks for high data rates under strict quality of service (QoS) constraints. To this end, this paper develops a novel link resource adaptation (LRA) scheme for soft-decoded multiantenna (MIMO) bit interleaved coded orthogonal frequency division multiplexing (BIC-OFDM) transmissions employing automatic repeat request (ARQ) mechanisms. As the first step, a simple link performance evaluation model based on the effective signal-to-noise ratio (SNR) mapping concept is derived in a closed-form expression that it is shown to yield better accuracy than previous techniques. Then, an effective LRA strategy is formulated taking advantage of that framework. The aim is maximizing the goodput (GP) metric, that is to say, the number of information bits delivered without error to the user by unit of time, over the available radio resources, such as the power distribution on the subchannels, coding rate, modulation order and the MIMO configuration. The numerical results demonstrate considerable performance gains compared with nonadaptive transmissions, while keeping the computational complexity at affordable levels in view of the specific structure of the GP objective function.

关键词： Automatic repeat request (ARQ) bit-interleaved coded modulation cross-layer link resource adaptation goodput multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) power allocation

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Adaptive bit loading and transmit diversity for iterative OFDM receivers

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WIRELESS PERSONAL COMMUNICATIONS 2008年第1期47卷 51-61页

作者： Sand, Stephan Mensing, Christian Mutti, Carlo Wittneben, Armin German Aerosp Ctr DLR Inst Commun & Nav D-82234 Oberpfaffenhofen Wessling Germany Swiss Fed Inst Technol Commun Technol Lab CH-8092 Zurich Switzerland

In this paper, we consider a transmission system employing orthogonal frequency division multiplexing with bit-interleaved coded modulation and perfect channel state information at both transmitter and receiver. An adaptive bit loading scheme in combination with cyclic delay diversity and discontinuous Doppler diversity is proposed at the transmitter and iterative demapping and decoding at the receiver. The loading procedure minimizes the bit-error rate at the decoder output, and the transmit diversity schemes mitigate channel correlations. We analyze the iterative receiver with extrinsic information transfer charts and present the achievable gains.

关键词： OFDM bit-interleaved coded modulation adaptive bit loading cyclic delay diversity discontinuous Doppler diversity iterative receiver EXIT chart

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Mapping Rearrangement for HARQ Based on Low-Order modulation

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IEEE TRANSACTIONS ON COMMUNICATIONS 2009年第5期57卷 1351-1358页

作者： Szczecinski, Leszek Ceron, Andres Feick, Rodolfo INRS EMT Montreal PQ H5A 1K6 Canada Univ Tecn Federico Santa Maria Dept Elect Engn Valparaiso Chile

In this paper we consider hybrid automatic repeat request transmission based on binary phase shift keying modulation. Our objective is to improve the performance of the retransmissions, keeping at the same time the complexity and the performance of the first transmission unaltered. We conclude that the so-called mapping rearrangement (MR) may considerably improve the performance if multi-dimensional modulation is applied. We evaluate the theoretical limits of bit-interleaved coded modulation with MR, verify the functioning of the practical coding scheme, and propose to improve the performance via iterative detection-decoding (BICM-ID) which brings considerable gains. In particular, for high coding rates, a 4 dB SNR gain over transmission without MR may be achieved.

关键词： Mapping rearrangement constellation rearrangement mapping diversity binary phase shift keying automatic repeat request iterative detection bit-interleaved coded modulation BICM ARQ BICM-ID BPSK QPSK

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Performance of BICM-ID with signal space diversity

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2007年第5期6卷 1732-1742页

作者： Tran, Nghi H. Nguyen, Ha H. Le-Ngoc, Tho Univ Saskatchewan Dept Elect Engn Saskatoon SK S7N 5A9 Canada McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 2A7 Canada

This paper presents a performance analysis of bit-interleaved coded-modulation with iterative decoding (BICM-ID) and complex N-dimensional signal space diversity in fading channels to investigate its performance limitation, the choice of the rotation matrix and the design of a low-complexity receiver. The tight error bound is first analytically derived. Based on the design criterion obtained from the error bound, the optimality of the rotation matrix is then established. It is shown that using the class of the optimal rotation matrices, the performance of BICM-ID systems over a Rayleigh fading channel approaches that of the BICM-ID systems over an AWGN channel when the dimension of the signal constellation increases. Furthermore, by exploiting the sigma mapping for any M-ary QAM constellation, a very simple sub-optimal, but yet effective iterative receiver structure suitable for signal constellations with large dimensions is proposed. Simulation results in various cases and conditions indicate that the proposed receiver can achieve the analytical performance bounds with low complexity.

关键词： bit-interleaved coded modulation iterative decoding signal space diversity performance analysis rotation matrix minimum mean-square error estimation

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