A New Algorithm for 16QAM Carrier Phase Estimation Using QPSK Partitioning

Rice, Feng; Rice, Mark; Cowley, William G.

doi:10.1006/dspr.2001.0400

Cited by 15 publications

(14 citation statements)

References 9 publications

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“…Referring to Fig. 5(a), the thresholds (T u ) which are used to decide annuli (S G ) can be set to some optimum values which may depend on the operating conditions [39]. In our simulations, however, we have obtained pair of thresholds for each QPSK-like symbol by simply bi-partitioning the annuli.…”

Section: Proposed Modificationsmentioning

confidence: 99%

“…QPSK-like partitioning of QAM constellation has been exploited in a number of recent articles including [38][39][40][41][42][43][44][45][46][47][48][49] and they have been studied largely for 16-and/or 64-QAM. Historically, the idea of QPSK partitioning of QAM signal first appeared in the work of Horikawa and Saitos in the year 1980 [50].…”

Section: Qpsk-like Partitioning Of Qammentioning

confidence: 99%

“…This stop-and-go strategy, however, strictly requires the recovery of true energy of the signal constellation in order to distinguish between signal points with amplitude variation. In practice, this can be achieved by using automatic gain control and digital signal processing methods [39].…”

Section: Proposed Modificationsmentioning

confidence: 99%

See 2 more Smart Citations

Blind adaptive carrier phase recovery for QAM systems

Abrar

Zerguine

Nandi

2016

Digital Signal Processing

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This paper provides a study of adaptive phase recovery in quadrature amplitude modulation (QAM) based communication systems. Here, we modify the traditional fourth-power phase recovery algorithm (FP-PRA) to propose three improved algorithms, and analyze their performances in the presence of additive white Gaussian noise, phase noise, frequency-offset, and inter-symbol interference. We demonstrate that it is possible to obtain the optimal values of step-sizes (or loop-gains) in closed-form in the presence of phase noise and/or frequency-offset. In particular, we discuss two methods to improve FP-PRA. The first method involves utilizing the idea of partitioning the QAM constellation into QPSK-like and not-QPSK-like annular regions. The phase synchronizer is allowed to update only when a derotated QAM symbol lies in QPSK-like region; otherwise, the update process is stopped. The second method exploits an evolving idea of QAM-to-QPSK transformation, and uses transformed symbols to estimate phase mismatch. We provide a new interpretation of this transformation method and relate it to the quadrant-wise centroid of the rotated constellation. Furthermore, we discuss the feasibility of this method for both square and cross-QAM, and, identify and verify numerically the existence of false-locks in the case of cross-QAM. To the best of our knowledge, the ideas of constellation partitioning and constellation transformation have not appeared earlier in the context of adaptive phase recovery. We discuss adaptive blind estimation of optimal step-sizes in the presence of phase noise and frequency-offset. Finally, we discuss the modification of the proposed stochastic gradient methods to transform them into batch processing algorithms so as to make them more suitable for higher data rate systems. Numerical experiments indicate that the proposed algorithms can outperform the traditional FP-PRA algorithm for a number of practical QAM sizes under different mismatch conditions, and that our analytical findings are in close agreement with the simulation results.

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Section: Proposed Modificationsmentioning

confidence: 99%

Section: Qpsk-like Partitioning Of Qammentioning

confidence: 99%

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Blind adaptive carrier phase recovery for QAM systems

Abrar

Zerguine

Nandi

2016

Digital Signal Processing

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“…This method, can be also used with higher order QAM signals [36] by partitioning them into distinct sets of QPSK constellations. It should be also noted that V&V algorithm may entirely replace traditional DPLL.…”

Section: Frequency and Phase Recoverymentioning

confidence: 99%

Anatomy of a Digital Coherent Receiver

Borkowski

Zibar

Monroy

2014

IEICE Trans. Commun.

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SUMMARYDigital coherent receivers have gained significant attention in the last decade. The reason for this is that coherent detection, along with digital signal processing (DSP) allows for substantial increase of the channel capacity by employing advanced detection techniques. In this paper, we first review coherent detection technique employed in the receiver as well as the required receiver structure. Subsequently, we describe the core part of the receiver -DSP algorithms -that are used for data processing. We cover all basic elements of a conventional coherent receiver DSP chain: deskew, orthonormaliation, chromatic dispersion compensation/nonlinear compensation, resampling and timing recovery, polarization demultiplexing and equalization, frequency and phase recovery, digital demodulation. We also describe novel subsystems of a digital coherent receiver: modulation format recognition and impairment mitigation via expectation maximization, which may gain popularity with increasing importance of autonomous networks.

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“…Boldface symbols denote vectors. The pdf of the received signal vector is given by (2) For a single received reference symbol, we have (3) where is known symbol, indicates the complex conjugate, and and stand for real and imaginary parts.…”

Section: Crlbs For Joint Frequency and Phase Estimationmentioning

confidence: 99%

Carrier-phase and frequency-estimation bounds for transmissions with embedded reference symbols

Rice

2006

IEEE Trans. Commun.

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Abstract-The true Cramér-Rao lower bound (CRLB) for the joint estimation of carrier phase and frequency is derived for transmission bursts with interleaved reference and phase-shift keying/quadrature amplitude modulated data symbols. Results are presented for the special cases of midamble, and preamble and postamble, pilot-symbol insertion. The derivation reveals that the CRLB is a function of the location of the reference symbols in the burst, the number of reference symbols, the number of data symbols, the signal-to-noise ratio and the data-modulation scheme. By distributing the reference symbols symmetrically about the center of the burst and analyzing relative to the middle of the signal vector, the joint frequency and phase estimation can be decoupled, and the optimal phase estimation is achieved. In the decoupled case, the phase CRLB is independent of the location of reference symbols in the burst. In a symmetrical burst, the use of a preamble and postamble is found to provide a lower frequency-estimation CRLB than that with a midamble. It appears that the frequency CRLB is reduced as the reference symbols are symmetrically distributed closer to the ends of the burst.

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A New Algorithm for 16QAM Carrier Phase Estimation Using QPSK Partitioning

Cited by 15 publications

References 9 publications

Blind adaptive carrier phase recovery for QAM systems

Blind adaptive carrier phase recovery for QAM systems

Anatomy of a Digital Coherent Receiver

Carrier-phase and frequency-estimation bounds for transmissions with embedded reference symbols

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