scholarly journals A Universal Low-Complexity Demapping Algorithm for Non-Uniform Constellations

2020 ◽  
Vol 10 (23) ◽  
pp. 8572
Author(s):  
Hao Wang ◽  
Mingqi Li ◽  
Chao Wang
Keyword(s):  
Euclidean Distance ◽  
Low Complexity ◽  
Coded Modulation ◽  
One Dimensional ◽  
Performance Loss ◽  
Point Analysis ◽  
Simulation Results ◽  
The One ◽  
Bit Interleaved Coded Modulation ◽  
Log Map

A non-uniform constellation (NUC) can effectively reduce the gap between bit-interleaved coded modulation (BICM) capacity and Shannon capacity, which has been utilized in recent wireless broadcasting systems. However, the soft demapping algorithm needs a lot of Euclidean distance (ED) calculations and comparisons, which brings great demapping complexity to NUC. A universal low-complexity NUC demapping algorithm is proposed in this paper, which creates subsets based on the quadrant of the two-dimensional NUC (2D-NUC) received symbol or the sign of the in-phase (I)/quadrature (Q) component of the one-dimensional NUC (1D-NUC) received symbol. ED calculations and comparisons are only carried out on the constellation points contained in subsets. To further reduce the number of constellation points contained in subsets, the proposed algorithm takes advantage of the condensation property of NUC and regards a constellation cluster containing several constellation points as a virtual point. Analysis and simulation results show that, compared with the Max-Log-MAP algorithm, the proposed algorithm can greatly reduce the demapping complexity of NUC with negligible performance loss.

A Low Complexity Implementation in Hardware on Simplified Log-MAP Algorithm for T-TCM Decoding

2013 ◽  
Vol 433-435 ◽  
pp. 1539-1544
Author(s):  
Jian Wang ◽  
Jian Ping Li
Keyword(s):  
Computational Complexity ◽  
Low Complexity ◽  
Coded Modulation ◽  
Maclaurin Series ◽  
Logarithmic Term ◽  
Map Algorithm ◽  
Trellis Coded ◽  
Low Complexity Implementation ◽  
Simulation Results ◽  
Log Map

A simplified decoding algorithm for turbo trellis-coded modulation (T-TCM) is proposed, which is easy to implement in hardware. The algorithm exploits a new piece-wise function to replace the logarithmic term of the Jacobian logarithm based on the MacLaurin Series. Simulation results show that the proposed algorithm can archive log-MAP-similar decoding performance with a much lower computational complexity. It can reduce about 40% of calculation in contrast to the improved MAX-Log-MAP.

Effect of Metal Intercalating on Transmission Characteristics of One-Dimensional Photonic Crystal

2011 ◽  
Vol 418-420 ◽  
pp. 679-683
Author(s):  
Bei Jia He ◽  
Xin Yi Chen ◽  
Jian Bo Wang ◽  
Jun Lu ◽  
Jian Chang ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Plasma Frequency ◽  
Fdtd Method ◽  
Transmission Characteristics ◽  
Material Characteristic ◽  
One Dimensional ◽  
Dimensional Photonic Crystal ◽  
Simulation Results ◽  
The One ◽  
Difference Time

To expand the bandgap's width of the one-dimensional photonic crystal, a crystal named SiO2/Metal/MgF2 is formed by joining some metals into the crystal SiO2/MgF2. Furthermore the Finite Difference Time Domain (FDTD) method is used to explore the metals' influence on the crystal's transmission characteristics. The simulation results show that the metals joined could expand the width of the one-dimensional photonic crystal's bandgap effectively and the bandgap's width increases when the metals' thickness increases. Meanwhile the bandgap's characteristic is affected by the metals' material-characteristic. The higher the plasma frequency is, the wider the bandgap's width will be and the more the number of the bandgaps will be. On the other hand, the metals' damping frequency has no significant effect on the bandgap, but would make the bandgap-edge's transmittance decrease slightly.

Cure Monitoring of Adhesive for Composite/Metal Bonded Structure Based on Highly Nonlinear Solitary Waves

2019 ◽  
Author(s):  
Wu Bin ◽  
Li Mingzhi ◽  
Liu Xiucheng ◽  
Wang Heying ◽  
He Cunfu ◽  
...  
Keyword(s):  
Solitary Wave ◽  
Solitary Waves ◽  
Curing Process ◽  
One Dimensional ◽  
Granular Chain ◽  
Highly Nonlinear ◽  
Highly Nonlinear Solitary Waves ◽  
Simulation Results ◽  
The One ◽  
Nonlinear Solitary Waves

Abstract In this paper, a nondestructive evaluation technique based on highly nonlinear solitary waves (HNSWs) is proposed to monitor the curing process of adhesive for composite/metal bonded structure. HNSWs are mechanical waves with high energy intensity and non-distortive nature which can form and propagate in a nonlinear system, such as a one-dimensional granular chain. In the present study, a finite element model of the one-dimensional granular chain is established with the commercial software Abaqus, to study the reflection behavior of HNSWs at the interface between the particle at the end of chain and the sample. The simulation results show that the time of flight (TOF) of the primary reflected solitary wave decreases with the stiffness of the sample increases, and the amplitude ratio (AR) between the primary reflected solitary wave and the incident solitary wave increases. An HNSWs transducer based on the one-dimensional granular chain is designed and fabricated. The relationship between the characteristic parameters of the primary reflected solitary wave (TOF and AR) and the curing time of adhesive for a composite/metal bonded structure is experimentally investigated. The experiment results suggest that the TOF decreases and the AR increases as the epoxy cures. The experimental results are in good agreement with the simulation results. This study provides a new characterization method for monitoring the curing process of adhesive for composite/metal bonded structure.

A Simplified CE Stopping Criterion for BICM-ID System

2013 ◽  
Vol 433-435 ◽  
pp. 1530-1534
Author(s):  
Miao Miao Li ◽  
Jian Ping Li
Keyword(s):  
Computational Complexity ◽  
Iterative Decoding ◽  
Rayleigh Fading ◽  
Coded Modulation ◽  
Cross Entropy ◽  
Stopping Criterion ◽  
Stopping Criteria ◽  
Adaptive Thresholds ◽  
Simulation Results ◽  
Bit Interleaved Coded Modulation

The iterative process of bit-interleaved coded modulation iterative decoding (BICM-ID) leads to the increase of computational complexity and decoding delay at the receiver, although it owns remarkable bit-error-rate (BER) performance both in additive Gaussian noise (AWGN) channel and Rayleigh fading channel. A variety of the stopping criteria are put forward to reduce the unnecessary iterations in the process. This paper presents a simplified cross-entropy (CE) stopping criterion based on CE criterion, which sets self-adaptive thresholds for different SNRs to decide whether to calculate the CE in the receiver. Simulation results show that the simplified CE criterion can obtain a better performance and lower computational complexity. The iterative number of the simplified CE criterion is about 12.2% less than the conventional CE criterion.

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