671 research outputs found
Blind Carrier Phase Recovery for General 2{\pi}/M-rotationally Symmetric Constellations
This paper introduces a novel blind carrier phase recovery estimator for
general 2{\Pi}/M-rotationally symmetric constellations. This estimation method
is a generalization of the non-data-aided (NDA) nonlinear Phase Metric Method
(PMM) estimator already designed for general quadrature amplitude
constellations. This unbiased estimator is seen here as a fourth order PMM then
generalized to Mth order (Mth PMM) in such manner that it covers general
2{\Pi}/M-rotationally symmetric constellations such as PAM, QAM, PSK.
Simulation results demonstrate the good performance of this Mth PMM estimation
algorithm against competitive blind phase estimators already published for
various modulation systems of practical interest.Comment: 14 pages, 12 figures, International Journal of Wireless & Mobile
Networks (IJWMN
Blind Phase Recovery in Cross QAM Communication Systems with the Reduced Constellation Eigth-Order Estimator (RCEOE)
The eighth-order (EOE) phase estimator [4] is modified to work for an eight-symbol symmetrical constellation, so that the large signal-to-noise (SNR) performance is not limited by self-noise. By using only the eight highest energy points of cross- QAM constellations, a reduced constellation eighth-order estimator (RCEOE) is proposed. Computer simulations for 128-QAM show that this new method performs substantially better than the recently introduced APP phase estimator of Wang et al. [8]. However, simulations with 32-QAM show little performance advantage of the RCEOE over the APP estimator, for SNR values normally of interest, whereas for low SNR, the improvement is significant. Application to any constellation which can be reduced to an 8-symbol quadrant symmetrical sub-constellation is straightforward
Low Complexity Blind Equalization for OFDM Systems with General Constellations
This paper proposes a low-complexity algorithm for blind equalization of data
in OFDM-based wireless systems with general constellations. The proposed
algorithm is able to recover data even when the channel changes on a
symbol-by-symbol basis, making it suitable for fast fading channels. The
proposed algorithm does not require any statistical information of the channel
and thus does not suffer from latency normally associated with blind methods.
We also demonstrate how to reduce the complexity of the algorithm, which
becomes especially low at high SNR. Specifically, we show that in the high SNR
regime, the number of operations is of the order O(LN), where L is the cyclic
prefix length and N is the total number of subcarriers. Simulation results
confirm the favorable performance of our algorithm
A Simple Improvement to the Viterbi and Viterbi Monomial-Based Phase Estimators
It is well known that the Viterbi and Viterbi Monomial- Based Phase Estimator, which includes the Mth Power Estimator, performs poorly for cross QAM signals. However, it is shown here that by allowing the power of the monomial to be negative, much improved performance can be realized at medium to high signalto- noise ratios (SNR). Monte Carlo simulations are used to demonstrate the efficacy of this novel simple extension, for 32- and 128-QAM systems. In principle, this extension can also be applied to other constellations, e.g., (4,12)-PSK
Benchmarking of Carrier Phase Recovery Circuits for M-QAM Coherent Systems
We benchmark blind carrier phase recovery DSP circuits in terms of SNR penalty, power dissipation, latency, area usage, and cycle slip probability, to identify optimal implementations for 16, 64, and 256QAM
A Summative Comparison of Blind Channel Estimation Techniques for Orthogonal Frequency Division Multiplexing Systems
The OFDM techniquei.e. Orthogonal frequency division multiplexing has become prominent in wireless communication since its instruction in 1950’s due to its feature of combating the multipath fading and other losses. In an OFDM system, a large number of orthogonal, overlapping, narrow band subchannels or subcarriers, transmitted in parallel, divide the available transmission bandwidth. The separation of the subcarriers is theoretically optimal such that there is a very compact spectral utilization. This paper reviewed the possible approaches for blind channel estimation in the light of the improved performance in terms of speed of convergence and complexity. There were various researches which adopted the ways for channel estimation for Blind, Semi Blind and trained channel estimators and detectors. Various ways of channel estimation such as Subspace, iteration based, LMSE or MSE based (using statistical methods), SDR, Maximum likelihood approach, cyclostationarity, Redundancy and Cyclic prefix based. The paper reviewed all the above approaches in order to summarize the outcomes of approaches aimed at optimum performance for channel estimation in OFDM system
Performance Prediction of Nonbinary Forward Error Correction in Optical Transmission Experiments
In this paper, we compare different metrics to predict the error rate of
optical systems based on nonbinary forward error correction (FEC). It is shown
that the correct metric to predict the performance of coded modulation based on
nonbinary FEC is the mutual information. The accuracy of the prediction is
verified in a detailed example with multiple constellation formats, FEC
overheads in both simulations and optical transmission experiments over a
recirculating loop. It is shown that the employed FEC codes must be universal
if performance prediction based on thresholds is used. A tutorial introduction
into the computation of the threshold from optical transmission measurements is
also given.Comment: submitted to IEEE/OSA Journal of Lightwave Technolog
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