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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2001年第8期19卷 1638-1645页

作者： AlRustamani, AA Damnjanovic, AD Vojcic, BR Dubai Internet City Dubai U Arab Emirates George Washington Univ Dept Elect & Comp Engn Washington DC 20052 USA George Washington Univ Dept Elect & Comp Engn Washington DC 20052 USA

Recently, a novel scheme for iterative multiuser detection and turbo decoding was proposed by Damnjanovic and Vojcic. In this scheme, multiuser detection and single-user turbo decoding are tightly coupled to maximize the overall gain. The extrinsic probabilities for the coded bits of the interfering users, obtained after each turbo decoding iteration, are used as a priori probabilities in the following multiuser iteration and the extrinsic information for the systematic bits of the desired user is used as a priori information in the next single-user turbo decoding iteration. Turbo decoding of parallel concatenated convolutional codes is carried out in parallel fashion. It has been shown that the proposed detector approaches the multiuser capacity limit within I dB in the low signal-to-noise ratio region. However, the main drawback of the scheme is its exponential complexity in the number of users, which is due to the complexity of the maximum a posteriori probability (MAP) multiuser detector. In this paper, we show that the complexity of the scheme can be significantly reduced by replacing the MAP multiuser detector with an iterative detector derived from the greedy multiuser detector proposed by AIRustamani and Vojcic. In this paper, we demonstrate that, for both the additive white Gaussian noise and the frequency-nonselective Rayleigh fading, the substantial reduction in complexity of the iterative scheme proposed by Damnjanovic and Vojcic when the greedy detector Is utilized introduces a slight degradation in performance;the loss in performance is less than or equal to 0.5 dB compared to MAP detector for systems with number of users double the spreading gain.

关键词： code division multiaccess concatenated coding iterative methods multiuser channels

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Turbo greedy multiuser detection

Turbo greedy multiuser detection

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International Conference on Telecommunications

关键词： code division multiaccess concatenated coding iterative methods multiuser channels

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An alternative to Reed-Solomon codes for forward error correction on optical channels

An alternative to Reed-Solomon codes for forward error corre...

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International Conference on Fiber Optics and Photonics (Photonics 2000)

作者： Colavolpe, G Prati, G Pagano, F Univ Parma Dipartimento Ingn Informaz I-43100 Parma Italy

ISBN: (纸本)0819441244

In this paper, forward error correction schemes are discussed for application in the multigigabit-per-second optical channel. The proposed schemes, based on specific convolutional codes which allow simple decoding techniques, represent a valid alternative, in terms of performance and complexity, to the recommended Reed-Solomon codes.

关键词： forward error correction convolutional codes concatenated coding

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Forced sequence sequential decoding: A concatenated coding system with iterated sequential inner decoding

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IEEE TRANSACTIONS ON COMMUNICATIONS 1998年第10期46卷 1280-1291页

作者： Jensen, OR Paaske, E Tech Univ Denmark Dept Telecommun DK-2800 Lyngby Denmark

In this paper, we describe a new concatenated decoding scheme based on iterations between an inner sequentially decoded convolutional code of rate R = 1/4 and memory M = 23, and block interleaved outer Reed-Solomon (RS) codes with nonuniform profile. With this scheme decoding with good performance is possible as low as E-b/N-o = 0.6 dB, which is about 1.25 dB below the signal-to-noise ratio (SNR) that marks the cutoff rate for the full system. Accounting for about 0.45 dB due to the outer codes, sequential decoding takes place at about 1.7 dB below the SNR cutoff rate for the convolutional code. This is possible since the iteration process provides the sequential decoders with side information that allows a smaller average load and minimizes the probability of computational overflow. Analytical results for the probability that the first RS word is decoded after C computations are presented. These results are supported by simulation results that are also extended to other parameters.

关键词： concatenated coding convolutional codes Fano decoding forced sequence decoding sequential decoding iterative decoding

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Iterative estimation and decoding for FH-SS with slow Rayleigh fading

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IEEE TRANSACTIONS ON COMMUNICATIONS 2000年第12期48卷 2014-2023页

作者： Kang, JH Stark, WE Univ Michigan Dept Elect Engn & Comp Sci Ann Arbor MI 48109 USA

In this paper, the performance of turbo codes is investigated in a frequency-hopped spread spectrum (FH-SS) system with full-band thermal noise and Rayleigh fading. For cases where the data rate exceeds the hopping rate (i.e., there exists multiple bits per hop) and fading side information (SI) does not exist, our approach is to iteratively estimate the fading levels. Simulation is performed for coherent and noncoherent reception, variable number of bits per hop, and cases where fading Si is available or unavailable to the decoder. It is shown that iterative channel estimation performed in conjunction with iterative decoding can improve the overall decoding performance. Finally, the performance of an FH-SS system using standard fading assumptions is compared to the performance of a measured fading channel. Due to flaws in assumptions, the measured fading channel yields several decibels of performance loss relative to the ideal fading channel.

关键词： concatenated coding fading channels frequency-hop communication spread-spectrum communication turbo codes

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Coded modulation for E²PR4 and ME²PR4 channels

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IEEE TRANSACTIONS ON MAGNETICS 2000年第6期36卷 4036-4043页

作者： Kuznetsov, AV Data Storage Inst Singapore 117608 Singapore

We consider a multilevel modulation scheme based on: 1) a structured set partition (SSP) of partial-response (PR) channel output words;2) a set of conventional block codes with different error-correcting capabilities, and 3) a Viterbi detector searching for the two best paths on the channel trellis. For the classic and modified:target polynomials, examples of SSPs with the good spectra of minimum-Euclidean:distances are given. Bit error rates (BERs) of the Proposed scheme ate investigated for the conventional(E(2)PR4) and modified (ME(2)PR4) channels with the target polynomials 1 + 2D - 2D(3) D-4 and 5 + 4D - 3D(2) - 4D(3) - 2D(4), respectively. Results of simulations show that a gain of 3.4 dB fan be achieved for linear densities of 2.5 to 3.0 and BER of 10(-6) without using any additional distance enhancing constraints [such as d = 1, maximum transition run (MTR), or;quasi-MTR].

关键词： concatenated coding iterative decoding list decoding modulation codes partial response channels recording codes set partitions turbo decoding

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Turbo decoding for partial response channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 2000年第8期48卷 1297-1308页

作者： Souvignier, TV Öberg, M Siegel, PH Swanson, RE Wolf, JK Texas Instruments Inc Longmont CO 80503 USA Marvell Semicond Inc Sunnyvale CA 94085 USA Univ Calif San Diego Dept Elect & Comp Engn La Jolla CA 92093 USA Seagate Technol Corp Fremont CA 94538 USA Univ Calif San Diego Ctr Magnet Recording Res La Jolla CA 92039 USA

The partial response channel can be viewed as a rate-1 encoder in which the output alphabet differs from the input alphabet. In serially concatenated coding schemes, the partial response channel can serve as the inner encoder, Recent work on the application of turbo decoding techniques to partial response channels has focused on using a parallel concatenation of convolutional encoders as the outer code and the partial response channel as the inner code. This system requires three a posteriori probability (APP) detectors-one matched to the channel and two matched to the constituent encoders. A simplified system will be presented that uses as its outer code a single convolutional code and as its inner code the partial response channel. The simplified system requires only two APP detectors, offering significant savings in complexity and computation time. This single convolutional code system will be shown to perform as well as the more complicated system, offering substantial gains over uncoded systems. Simulation results for three magnetic recording channel models will be presented: a partial response channel with additive white Gaussian noise, an equalized Lorentzian channel model, and a media noise model called the microtrack model, Since the use of an outer Reed-Solomon code is anticipated in an actual system, the burst-error statistics are investigated. System performance with various interleaver designs and precoders is also investigated.

关键词： concatenated coding iterative methods partial response signaling turbo codes

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Turbo decoding for high-rate concatenated parity-check codes on PRML channels

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IEEE TRANSACTIONS ON MAGNETICS 2000年第5期36卷 2173-2175页

作者： Sawaguchi, H Wolf, JK Hitachi Ltd Cent Res Lab Kokubunji Tokyo 1858601 Japan Univ Calif San Diego Ctr Magnet Recording Res La Jolla CA 92093 USA

A simple turbo decoding scheme is proposed for partial-response (PR) channels by using high-rate parity-check codes as an outer error-correction code (ECC), The use of the simple parity codes enables a simplified and high-speed implementation of the a posterior probability (APP) decoder. Its key feature is an iterative decoding step for the parallel concatenation of two parity-check outer codes connected via an interleaver, The parity iterative decoding can provide the high-rate parity-check outer codes with superior correction capability for random error-events, so it can help to reduce the decoding latency, The combination of the serial turbo decoding for a modified E-2 PR ((MEPR)-P-2) channel and the parity iterative decoding demonstrated a coding gain of 4-5 dB at a bit error rate of 1.0E-5 for a coding rate of 8/9.

关键词： concatenated coding turbo iterative decoding parity-check code partial response signaling

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Performance of timing recovery methods in turbo coded magnetic recording channels

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IEEE TRANSACTIONS ON MAGNETICS 2000年第5期36卷 2187-2189页

作者： Yuan, YF Kurtas, E Kumar, BVKV Carnegie Mellon Univ DSSC Pittsburgh PA 15213 USA Seagate Technol Pittsburgh PA 15203 USA

Turbo codes, with potential 4 to 5 dB coding gain over the conventional Viterbi detection schemes, are good candidates for the next generation detection/decoding schemes for magnetic recording systems. In this paper, timing recovery is included in the evaluation of Turbo codes. Three timing recovery methods, namely voltage control oscillator (VCO) method, interpolated timing recovery (ITR) method and adaptive filter timing recovery (AFTR) method are examined for two turbo decoder architectures, full turbo and serial turbo. Bit error rate (BER) results from simulations suggest that full turbo decoder is more robust than the serial turbo decoder. For serial turbo decoder, error floor is seen earlier in VCO and ITR methods than AFTR method. Using s-random interleaver seems to be able to remove such error floor.

关键词： adaptive filter concatenated coding partial response signaling timing recovery turbo codes

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Turbo decoding for partial response channels using spinstand data

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IEEE TRANSACTIONS ON MAGNETICS 2000年第5期36卷 2167-2169页

作者： Souvignier, T Keirn, Z Xu, C Texas Instruments Inc Longmont CO 80503 USA

The partial response channel can be viewed as a rate-1 encoder in which the output alphabet differs from the input alphabet. in serially concatenated coding schemes, the partial response channel can serve as the inner encoder, Recent works on the application of turbo decoding techniques to partial response channels have used channel models to investigate system performance. While the models provided some insight into the performance of turbo decoding techniques, performance in a real system, with electronic and signal-dependent media noise, remained unknown. This paper will demonstrate the performance of turbo decoding techniques using real and modeled spinstand data. A simple serial concatenation system will be presented that uses as its outer code a single convolutional code and as its inner code the partial response channel. Significant gains will be shown over QMTR coded systems.

关键词： codes concatenated coding error correction iterative methods partial response signaling turbo codes

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