A carrier phase estimator for multimedia satellite payloads suited to RSC coding schemes

Morlet, C.; Buret, Isabelle; Boucheret, Marie‐Laure

doi:10.1109/icc.2000.853360

Cited by 14 publications

(8 citation statements)

References 5 publications

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“…Furthermore, in [11,12], for instance, it is proposed to combine softdecision-directed carrier phase estimation with turbo decoding. Tentative decision-aided synchronization within a turbo decoder is reported in [13,14].…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Framework for Soft-Information-Based Synchronization in Iterative (Turbo) Receivers

Noels

Lottici

Dejonghe

et al. 2005

J Wireless Com Network

100

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This contribution considers turbo synchronization, that is to say, the use of soft data information to estimate parameters like carrier phase, frequency, or timing offsets of a modulated signal within an iterative data demodulator. In turbo synchronization, the receiver exploits the soft decisions computed at each turbo decoding iteration to provide a reliable estimate of some signal parameters. The aim of our paper is to show that such “turbo-estimation” approach can be regarded as a special case of the expectation-maximization (EM) algorithm. This leads to a general theoretical framework for turbo synchronization that allows to derive parameter estimation procedures for carrier phase and frequency offset, as well as for timing offset and signal amplitude. The proposed mathematical framework is illustrated by simulation results reported for the particular case of carrier phase and frequency offsets estimation of a turbo-coded 16-QAM signal.

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Section: Introductionmentioning

confidence: 99%

A Theoretical Framework for Soft-Information-Based Synchronization in Iterative (Turbo) Receivers

Noels

Lottici

Dejonghe

et al. 2005

J Wireless Com Network

100

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“…However, in the turbo-coded system, the extrinsic information is available after the first decoding iteration, from which we can obtain the probabilities of each possible transmitted symbol given the received signal, represented as , meaning the probability that the th transmitted signal is the th constellation point. Averaging the likelihood function over the constellation using these probabilities, we get the likelihood function for the proposed method, (5) Take the logarithm of (5), then the LLF turns out to be (6) where is defined as LLF for each individual symbol (7) and the overall LLF (6) can be looked upon as the summation of over symbols. In the following, we derive the LLF in binary phase-shift keying (BPSK) and quaternary phase-shift keying (QPSK) modulation separately.…”

Section: A Log-likelihood Functionmentioning

confidence: 99%

“…The estimation of channel phase and data is done jointly, on the supertrellis, which merges the trellises of the code and phase model, or on the separate trellises, via the Forward-Backward algorithm. Publications [6]- [9] present methods using soft output generated by the turbo decoder to aid the phase recovery. Morlet et al [6] presents a tentative decision directed carrier phase estimation technique, where tentative symbol decisions calculated by the Viterbi decoder are used to replace the data decision in the DD method.…”

mentioning

confidence: 99%

“…Publications [6]- [9] present methods using soft output generated by the turbo decoder to aid the phase recovery. Morlet et al [6] presents a tentative decision directed carrier phase estimation technique, where tentative symbol decisions calculated by the Viterbi decoder are used to replace the data decision in the DD method. The approach proposed in [7] is specifically geared for turbo coding.…”

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confidence: 99%

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Iterative Carrier Phase Recovery Suited to Turbo-Coded Systems

Zhang

Burr

2004

IEEE Trans. Wireless Commun.

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Abstract-This paper examines the problem of carrier phase recovery in turbo-coded systems. We introduce a new concept of "a priori probability aided phase estimation", where the extrinsic information (log-likelihood ratio) obtained from turbo decoder is used to aid an iterative phase estimation process, which is based on a maximum-likelihood strategy. The phase estimator operates jointly with the turbo decoding rather than separately prior to the decoder as in traditional approaches. This technique provides reliable phase estimation with variance of estimation errors approaching the Cramer-Rao bound at very low signal-to-noise ratio and allows robust decoding with a wide range of phase errors. This paper addresses its application in turbo-coded binary phase-shift keying and quaternary phase-shift keying systems over the additive white Gaussian noise channel. The bit-error-rate performance is investigated and shows that the performance of this technique is very close to the optimally synchronised system and significantly outperforms the traditional non-data-aided method without using additional pilot symbols.Index Terms-A priori information, Cramer-Rao bound (CRB), extrinsic information, iterative decoding, log-likelihood function (LLF), MAP, maximum-likelihood (ML) estimation, turbo codes.

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“…Some of the methods use an outer encoder (convolutional, LDPC or turbo code) followed by a modulation encoder, with iterative decoding between them on the receiver side [1], [5], [7], [8], [9], [12], [13]. Typically the outer and modulation encoders are separated by an interleaver.…”

Section: Introductionmentioning

confidence: 99%

Joint Carrier Phase Estimation and Turbo Decoding Using Bit Carrier Phase APP Decoder

Saroka

Raphaeli

2007

IEEE Trans. Commun.

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-In this paper we present an algorithm for joint carrier phase estimation and turbo decoding for the case of rapidly varying carrier phase during the transmitted block. The proposed algorithm shows improved performance over previously proposed communication schemes, both coherent and non-coherent, for channels with Additive White Gaussian Noise (AWGN) and high carrier phase noise. The novel algorithm utilizes a modified "two dimensional" Bit-Carrierphase A Posteriori Probability (BCAPP) decoder containing additional states representing the received carrier phase. The BCAPP decoder calculates two extrinsic metrics; one representing the bit soft value and the other representing the received carrier phase Probability Density Function (PDF) approximation. A modified structure of the turbo code iterations is suggested, implementing separate propagation of the two metrics between the BCAPP decoders. Most known methods to combat very high phase noise in the channel at low signal to noise ratio are based on non-coherent demodulation. Such reception schemes are designed for the worst-case phase noise and suffer high degradation for any level of phase noise. In our scheme, together with improved performance in high phase noise, the degradation decreases with the actual channel phase noise level. We show the robustness against phase noise model mismatch.

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A carrier phase estimator for multimedia satellite payloads suited to RSC coding schemes

Cited by 14 publications

References 5 publications

A Theoretical Framework for Soft-Information-Based Synchronization in Iterative (Turbo) Receivers

A Theoretical Framework for Soft-Information-Based Synchronization in Iterative (Turbo) Receivers

Iterative Carrier Phase Recovery Suited to Turbo-Coded Systems

Joint Carrier Phase Estimation and Turbo Decoding Using Bit Carrier Phase APP Decoder

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