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Communications over phase noise channels: a tutorial review

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING 2014年第3期32卷 167-185页

作者： Colavolpe, Giulio Univ Parma Dipartimento Ingn Informaz I-43100 Parma Italy

In this tutorial paper, we first review the main information-theoretic results on channels affected by a time-varying phase noise. The main maximum a posteriori symbol detection algorithms to be employed in such a challenging scenario are then described considering linear modulations and advanced coding schemes based on iterative detection and decoding. The role of pilot symbols will be also discussed. Copyright (C) 2013 John Wiley & Sons, Ltd.

关键词： information rate iterative detection and decoding phase noise

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Centralized and Decentralized IDD Schemes for Cell-Free Massive MIMO Systems: AP Selection and LLR Refinement

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IEEE ACCESS 2024年 12卷 62392-62406页

作者： Ssettumba, Tonny Shao, Zhichao Landau, Lukas T. N. Facina, Michelle Soares Pereira da Silva, Paulo Ricardo Branco de Lamare, Rodrigo C. Pontif Catholic Univ Rio De Janeiro PUC Rio Dept Elect Engn DEE BR-22451900 Rio De Janeiro Brazil Univ Elect Sci & Technol China Yangtze Delta Reg Inst Quzhou Quzhou 324003 Peoples R China Fdn Ctr Pesquisa & Desenvolvimento Telecomunicacoe BR-13086902 Campinas Brazil

In this paper, we propose iterative interference cancellation schemes with access points selection (APs-Sel) for cell-free massive multiple-input multiple-output (CF-mMIMO) systems. Closed-form expressions for centralized and decentralized linear minimum mean square error (LMMSE) receive filters with APs-Sel are derived assuming imperfect channel state information (CSI). Based on the derived expressions, insights are drawn and general expressions are devised for several cases, namely: firstly, MMSE-SIC filter for the non-scalable CF-mMIMO that uses all APs. Secondly, an MMSE-SIC filter assuming perfect channel state information. Thirdly, in this case we assume no interference cancellation and the linear MMSE filter is obtained. Additionally, we formulate a new Gaussian approximation of the likelihood function by deriving new closed-form expressions for the second order statistics (mean and variance) of the detected signal parameters in presence of channel estimation errors, APs-Sel matrix and multi-user interference (MUI). Since the MMSE-SIC filter experiences error propagation due to erroneous decisions from the previous stages, we develop a list-based detector based on LMMSE receive filters for CF-mMIMO systems that exploits interference cancellation and the constellation points to mitigate the error propagation that occurs in conventional MMSE-SIC receivers. An iterative detection and decoding (IDD) scheme that employs low-density parity-check codes is then developed. Moreover, log-likelihood ratio (LLR) refinement strategies based on censoring and a linear combination of local LLRs are proposed to improve the network performance. We assess the proposed centralized and decentralized IDD schemes against existing approaches in terms of bit error rate performance, complexity, and signaling under perfect CSI and imperfect CSI and verify the superiority of the distributed IDD architecture with LLR refinements.

关键词： Detectors Filters Channel estimation Symbols Uplink MIMO communication Decentralized applications Cell-free massive MIMO systems centralized processing decentralized processing iterative detection and decoding list-based detectors

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Soft-Input Soft-Output List Sphere detection with a Probabilistic Radius Tightening

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2012年第8期11卷 2848-2857页

作者： Lee, Jaeseok Shim, Byonghyo Kang, Insung Korea Univ Sch Informat & Commun Seoul South Korea Qualcomm Inc San Diego CA 92121 USA

In this paper, we present a low-complexity list sphere detection algorithm for achieving near-optimal a posteriori probability (APP) detection in an iterative detection and decoding (IDD). Motivated by the fact that the list sphere decoding searching a fixed number of candidates is computationally inefficient in many scenarios, we design a criterion to search lattice points with non-vanishing likelihood and then derive a hypersphere radius satisfying this condition. Further, in order to exploit the original sphere constraint as it is instead of using necessary conditioned version, we combine a probabilistic tree pruning strategy and the proposed list sphere search. Two features, tightened hypersphere radius and probabilistic tree pruning, collaborate and improve the search efficiency in a complementary fashion. Through simulations on 4 x 4 MIMO system, we show that the proposed method provides substantial reduction in complexity while achieving negligible performance loss over the conventional list sphere detection.

关键词： Sphere decoding iterative detection and decoding a posteriori probability probabilistic radius tightening multiple-input multiple-output system complexity reduction

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Simplified soft-output detection of CPM signals over coherent and phase noise channels

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2007年第7期6卷 2486-2496页

作者： Barbieri, Alan Colavolpe, Giulio Univ Parma Dipartimento Ingn Informaz I-43100 Parma Italy

We consider continuous phase modulations (CPMs) in iteratively decoded serially concatenated schemes. Although the overall receiver complexity mainly depends on that of the CPM detector, almost all papers in the literature consider the optimal maximum a posteriori (MAP) symbol detection algorithm and only a few attempts have been made to design low-complexity suboptimal schemes. This problem is faced in this paper by first considering the case of an ideal coherent detection, then extending it to the more interesting case of a transmission over a typical satellite channel affected by phase noise. In both cases, we adopt a simplified representation of an M-ary CPM signal based on the principal pulses of its Laurent decomposition. Since it is not possible to derive the exact detection rule by means of a probabilistic reasoning, the framework of factor graphs (FGs) and the sum-product algorithm (SPA) is used. In the case of channels affected by phase noise, continuous random variables representing the phase samples are explicitly introduced in the FG. By pursuing the principal approach to manage continuous random variables in a FG, i.e., the canonical distribution approach, two algorithms are derived which do not require the presence of known (pilot) symbols, thanks to the intrinsic differential encoder embedded in the CPM modulator.

关键词： factor graphs sum-product algorithm continuous phase modulation iterative detection and decoding detection and decoding in the presence of phase noise

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Dynamic Grain State Estimation for High-Density TDMR: Progress and Future Directions

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IEEE TRANSACTIONS ON MAGNETICS 2016年第2期52卷 1-7页

作者： Sun, Xueliang Belzer, Benjamin J. Sivakumar, Krishnamoorthy Washington State Univ Sch Elect Engn & Comp Sci Pullman WA 99164 USA

Dynamic grain state estimation (DGSE) algorithms for 2-D magnetic recording (TDMR) employ probabilistic message-passing algorithms that jointly estimate magnetic grain configurations and coded data bits, in order to iteratively assist channel decoding. At high densities (e.g., between 1 and 3 magnetic grains per coded bit), occasionally, a bit will not be written on any grain, and hence will effectively be overwritten (or erased) by bits on surrounding grains. DGSE enables the detection of overwritten bits so that their log-likelihood ratios are assigned small magnitudes, effectively making them erasures, which are easily filled in by linear channel codes. Past papers employing Bahl-Cocke-Jelinek-Raviv-based detectors on a simple four-rectangular-grain model have shown that the DGSE is surprisingly resilient to mismatch between the detector's assumed grain model and the actual model generating the data. This paper presents a novel DGSE-TDMR detector based on the generalized belief propagation (GBP) algorithm. The new detector employs a random discretized-nuclei Voronoi grain model. Simulation results show that the GBP-based TDMR turbodetector accurately detects the overwritten bits and that it achieves low decoded bit error rates at densities as high as 0.4966 user bits per grain.

关键词： 2-D magnetic recording (TDMR) generalized belief propagation (GBP) iterative detection and decoding Voronoi grain model

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High Density Turbo TDMR detection With Local Area Influence Probabilistic Model

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IEEE TRANSACTIONS ON MAGNETICS 2017年第2期53卷 1-8页

作者： Sun, Xueliang Sivakumar, Krishnamoorthy Belzer, Benjamin J. Wood, Roger Washington State Univ Sch Elect Engn & Comp Sci Pullman WA 99164 USA HGST Inc San Jose CA 95119 USA

This paper proposes probabilistic message-passing turbo detection algorithms for 2-D magnetic recording that locally estimate magnetic grain interactions with coded data bits, and thus iteratively assist channel decoding. Such local area influence probabilistic (LAIP) techniques are especially effective at densities ranging from about 4 magnetic grains per coded bit (GPB) down to about 1 GPB, where interaction between grains and bits is significant and occasionally a bit will not be written on any grain, and hence will effectively be "overwritten" by bits on surrounding grains. By modeling the interaction among grains, LAIP enables detection of both overwritten bits and wrong-sign non-overwritten bits so that their log-likelihood ratios are assigned small magnitudes for overwritten bits and correct signs for non-overwritten bits. Simulation results with a random Voronoi magnetic media model show that the LAIP-based detector can accurately detect both overwritten bits and severely influenced non-overwritten bits, and that higher user densities and lower bit error rates can be achieved compared with our previously proposed generalized belief propagation (GBP) detector presented at the 2015 Magnetic Recording Conference (TMRC 2015). In addition, the LAIP-based detector's computer run time is 10 000 times faster than the GBP-based detector.

关键词： iterative detection and decoding local area influence probabilistic (LAIP) model two-dimensional magnetic recording (TDMR) Voronoi grain model

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decoding by Sampling - Part II: Derandomization and Soft-Output decoding

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IEEE TRANSACTIONS ON COMMUNICATIONS 2013年第11期61卷 4630-4639页

作者： Wang, Zheng Liu, Shuiyin Ling, Cong Univ London Imperial Coll Sci Technol & Med Dept Elect & Elect Engn London SW7 2AZ England Monash Univ Dept Elect & Comp Syst Engn Melbourne Vic 3180 Australia

In this paper, a derandomized algorithm for sampling decoding is proposed to achieve near-optimal performance in lattice decoding. By setting a probability threshold to sample candidates, the whole sampling procedure becomes deterministic, which brings considerable performance improvement and complexity reduction over to the randomized sampling. Moreover, the upper bound on the sample size K, which corresponds to near-maximum likelihood (ML) performance, is derived. We also find that the proposed algorithm can be used as an efficient tool to implement soft-output decoding in multiple-input multiple-output (MIMO) systems. An upper bound of the sphere radius R in list sphere decoding (LSD) is derived. Based on it, we demonstrate that the derandomized sampling algorithm is capable of achieving near-maximum a posteriori (MAP) performance. Simulation results show that near-optimum performance can be achieved by a moderate size K in both lattice decoding and soft-output decoding.

关键词： Lattice decoding sampling algorithms lattice reduction soft-output decoding iterative detection and decoding

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ISI/ITI Turbo Equalizer for TDMR Using Trained Local Area Influence Probabilistic Model

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IEEE TRANSACTIONS ON MAGNETICS 2019年第4期55卷 1-15页

作者： Sun, Xueliang Shen, Jinlu Belzer, Benjamin J. Sivakumar, Krishnamoorthy James, Ashish Chan, Kheong Sann Wood, Roger Quantamental Technol LLC White Plains NY 10606 USA Washington State Univ Sch Elect Engn & Comp Sci Pullman WA 99164 USA ASTAR Inst Infocomm Res Singapore Singapore Nanjing Inst Technol Nanjing 211167 Jiangsu Peoples R China

In this paper, a local area influence probabilistic (LAIP) detector for estimating magnetic grain interactions with coded data bits in two-dimensional magnetic recording is combined with a 2-D Bahl-Cocke-Jelinek-Raviv (BCJR)-based detector for joint removal of intertrack interference (ITI) and intersymbol interference (ISI). The LAIP detector sends log-likelihood ratio estimates of coded bits and an estimate of the local ISI/ITI convolution mask to a BCJR-based ISI/ITI detector followed by an irregular-repeat-accumulate decoder. Simulation results on a random Voronoi grain media model with ISI and ITI show that the concatenated LAIP/BCJR system, which detects three tracks simultaneously, achieves user information bit areal densities competitive or higher than results reported in a previous paper that employed the LAIP detector alone on a Voronoi grain channel without ISI/ITI. Simulation results on a grain-flipping probability media model based on micromagnetic simulations show that the proposed detector achieves an 11.3% bit error rate reduction compared to a recently proposed system with a 2-D linear equalizer followed by a two-track BCJR detector with 2-D pattern-dependent noise prediction.

关键词： Grain-flipping probability (GFP) model iterative detection and decoding local area influence (LAI) probability two-dimensional magnetic recording (TDMR) Voronoi grain model

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Iterations of FB-MSDSD and Turbo Codes over the Correlated Flat Fading Channel

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2011年第12期E94A卷 2780-2786页

作者： Chen, Chien-Sheng Lo, Ching-Chi Tainan Univ Technol Dept Informat Management Tainan Taiwan Telecom Technol Ctr Kaohsiung Taiwan

Over a correlated flat fading channel, multiple-symbol differential detection can enhance the performance of coded differential phase shift keying (DPSK) systems but with exponential complexity. For iterative decoding schemes, the soft-input soft-output (SISO) multiple-symbol. differential sphere decoding (MSDSD) can offer suboptimal performance and its complexity is quadratic with detection length. To further reduce the complexity, this paper proposes a Forward/Backward MSDSD (FB-MSDSD) for coded DPSK systems. The key idea is that the detection interval is split into two subintervals which are processed in the forward and backward directions respectively. Simulation results show that the proposed scheme has almost the same performance and lower complexity when compared with the SISO-MSDSD scheme with the same detection length.

关键词： FB-MSDSD turbo codes iterative detection and decoding

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The impact of channel estimation errors and co-antenna interference on the performance of a coded MIMO system

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EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING 2005年第11期2005卷 1680-1697页

作者： Mysore, N Bajcsy, J McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 2A7 Canada

This paper considers the problem of uplink transmission over multiple-input multiple-output (MIMO) channels affected by slow frequency-nonselective uncorrelated and correlated Rayleigh fading. We consider the case when channel state information, corrupted by estimation errors, is available at the receiver only. In this setting, we generalize the derivation of our previously proposed linear-complexity MIMO signal detector and derive closed-form expressions for the distribution of its soft outputs and the approximate symbol error probability. Based on this soft decision detector, we consider a turbo-coded MIMO uplink architecture with iterative processing, which enables performance within 1.6 to 2.8 dB of the ergodic capacity limit and outperforms the T-BLAST (turbo-Bell Laboratories layered space-time) system by about 10 dB at bit error rates of 10(-5). The presented results illustrate that this linear-complexity MIMO signal detector is highly robust to channel estimation errors.

关键词： coded MIMO systems channel estimation errors MIMO signal detection iterative detection and decoding

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