Embedding Carrier Phase Recovery Into Iterative Decoding of Turbo-Coded Linear Modulations

Lottici, Vincenzo; Luise, Marco

doi:10.1109/tcomm.2004.826353

Cited by 120 publications

(55 citation statements)

References 16 publications

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“…This requires resetting the BICM detector and performing many detection iterations. We use the embedded estimation procedure [28] to avoid this overhead: when the parameters h (k) eq and τ (k) are updated, the BICM detector is not reset, but keeps the extrinsic and a priori probabilities from the previous iteration of the BICM detector. In this case, the overhead related to the proposed SAGE estimation algorithm becomes reasonable.…”

Section: The Following Remarks Are Of Interestmentioning

confidence: 99%

Novel Data Detection and Channel Estimation Algorithms for BICM-OFDMA Uplink Asynchronous Systems in the Presence of IQ Imbalance

Marey

Steendam

2014

IEEE Trans. Wireless Commun.

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Abstract-The problem of channel estimation and inphase/quadrature-phase (IQ) imbalance is one of the main challenges that has to be faced by uplink transmission in orthogonal frequency division multiple access (OFDMA) systems. The previously reported investigations for such systems are limited to synchronous and uncoded transmission. Furthermore, in these previous works, equalization of the IQ imbalance should be performed after the estimation process in order to properly detect data symbols. In this contribution, the transmit and receive IQ imbalance for uplink OFDMA systems is investigated in the context of asynchronous and bit-interleaved coded modulation (BICM) transmission. We propose a novel data detector exploiting the unwanted IQ as a beneficial resource to achieve a diversity gain, without the necessity of an additional equalizer. In addition, we develop a novel code-aided algorithm to estimate the propagation delays and the overall channel impulse responses (CIRs), which include the physical CIRs and IQ imbalance occurring at both the transmitters and base station. Since the exact maximum-likelihood (ML) solution to this problem turns out to be too complex for practical purposes, we resort to the space alternating generalized expectation-maximization (SAGE) algorithm as a low complexity method to perform parameter estimation. The proposed estimation algorithm operates in an iterative way, in which the soft information provided by the channel decoder is utilized as a priori information to refine the estimates. The computational complexity analysis and simulation results confirm the effectiveness of the proposed estimation algorithm and the proposed detector for practical application.

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Section: The Following Remarks Are Of Interestmentioning

confidence: 99%

Novel Data Detection and Channel Estimation Algorithms for BICM-OFDMA Uplink Asynchronous Systems in the Presence of IQ Imbalance

Marey

Steendam

2014

IEEE Trans. Wireless Commun.

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“…The authors in [11] have developed a blind recovery technique for QAM receivers. The work in this paper is also based on blind, or pilotless, operation and we motivate this in part by recalling a result from Anastasopoulos [3] who showed pilotless techniques to be more efficient at lower SNRs where pilot insertion loss is considerable.…”

Section: Introductionmentioning

confidence: 99%

Pilotless carrier phase-synchronization via LDPC code feedback

Valles

Wesel

Villasenor

et al. 2010

2010 - Milcom 2010 Military Communications Conference

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Abstract-This paper addresses the carrier-phase estimation problem under the low SNR conditions often encountered in turbo and LDPC-coded applications. In [1] a decision-directed carrier synchronization (DDCS) circuit that uses soft information from an iterative LDPC decoder was presented for BPSK and QPSK constellations with constant phase offsets. In this work, we present a method that is able to handle arbitrary constellations with a random-walk phase noise process. Loop SNR equations are derived and the performance for different constellations is shown. An extension of the DDCS algorithm is described that uses a search and tracking method based on measuring the number of satisfied LDPC constraint-node equations equations at the decoder and is able to track arbitrary carrier phase.

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“…This can be accomplished, in an efficient way, by applying the SPA to the FG representing the joint APP distribution function of , , and 4 (5) where we have assumed that the information symbols are independent, uniformly, and identically distributed (hence, ), we have denoted by the code indicator function, equal to 1 if is the codeword corresponding to and to zero otherwise, and finally, due to the phase model (2), we have used the conditional Markov property and discarded the term since is uniformly distributed. The pdf can be further expressed as (6) whereas the term in (5) is given by…”

Section: Proposed Algorithmmentioning

confidence: 99%

“…6 By applying the SPA, we find and by simple manipulations, we have (22) To simplify the algorithm, in this case, we can also use the approximation . To summarize, one iteration of the proposed joint detector/ decoder is formed by the following basic steps:…”

Section: Proposed Algorithmmentioning

confidence: 99%

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Joint iterative detection and decoding in the presence of phase noise and frequency offset

Barbieri

Colavolpe

Caire

IEEE International Conference on Communications, 2005. ICC 2005. 2005

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Abstract-We present a new algorithm for joint detection and decoding of iteratively decodable codes transmitted over channels affected by a time-varying phase noise (PN) and a constant frequency offset. The proposed algorithm is obtained as an application of the sum-product algorithm to the factor graph representing the joint a posteriori distribution of the information symbols and the channel parameters given the channel output. The resulting algorithm employs the soft-output information on the coded symbols provided by the decoder and performs forwardbackward recursions, taking into account the joint probability distribution of phase and frequency offset. We present simulation results for high-order coded modulation schemes based on low-density parity-check codes and serially concatenated convolutional codes, showing that, despite its low complexity, the algorithm is able to cope with a strong PN and a significant uncompensated frequency offset, thus avoiding the use of complicated data-aided frequency-estimation schemes operating on a known preamble. The robustness of the algorithm in the presence of a time-varying frequency offset is also discussed.Index Terms-Detection and decoding in the presence of phase noise and frequency offset, factor graphs (FGs), iterative detection and decoding, low-density parity-check (LDPC) codes, serially concatenated convolutional codes (SCCCs), sum-product algorithm (SPA), turbo codes (TCs).

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Embedding Carrier Phase Recovery Into Iterative Decoding of Turbo-Coded Linear Modulations

Cited by 120 publications

References 16 publications

Novel Data Detection and Channel Estimation Algorithms for BICM-OFDMA Uplink Asynchronous Systems in the Presence of IQ Imbalance

Novel Data Detection and Channel Estimation Algorithms for BICM-OFDMA Uplink Asynchronous Systems in the Presence of IQ Imbalance

Pilotless carrier phase-synchronization via LDPC code feedback

Joint iterative detection and decoding in the presence of phase noise and frequency offset

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