Optimization of LDPC Coded IDMA System

2011 ◽  
Vol 148-149 ◽  
pp. 1066-1071
Author(s):  
Jing Xi Zhang
Keyword(s):  
Iterative Process ◽  
Iterative Decoding ◽  
Ldpc Code ◽  
The Other ◽  
Performance Gain ◽  
Check Matrix ◽  
Outer Iteration ◽  
Iteration Number ◽  
Inner Iteration ◽  
Elementary Signal

The issue of optimization of LDPC Coded IDMA system is studied. The iterative decoding process of LDPC code is called inner iteration, and the iterative process between LDPC code and elementary signal estimator (ESE) is called outer iteration. The performance of the system is shown by BER and the complexity is indicated by iteration number. Check matrix is constructed randomly based on the obtained degree profile and simulations are made. The results show that performance of the system improves as the iteration number increases, either inner or outer iteration number. On the other hand, the performance gain of the system decreases with the increase of iteration number. Besides, the performance can be improved by reasonable setting of iteration number with the same complexity.

scholarly journals Wuzzit Trouble: The Influence of a Digital Math Game on Student Number Sense

2015 ◽  
Vol 2 (4) ◽  
Author(s):  
Holly Pope ◽  
Charmaine Mangram
Keyword(s):  
Decision Making ◽  
Iterative Process ◽  
Number Sense ◽  
The Other ◽  
Third Grade Students ◽  
Student Number ◽  
Mathematical Proficiency ◽  
Comparison Groups ◽  
Math Game ◽  
Post Assessment

This study sought to determine if playing a digital math game could increase student number sense (mathematical proficiency in numeracy). We used a pre- and post-assessment to measure the number sense of two groups of third grade students with the same mathematics teacher. One group played the game Wuzzit Trouble and the other did not. Overall, the group who played Wuzzit Trouble showed a significant increase in number sense between the pre- and post-assessment, compared to the other group who did not. A qualitative analysis of a novel problem revealed differences between the treatment and comparison groups from pre- to post-. A discussion of these findings and features of the game are addressed. Namely, two features inherent in Wuzzit Trouble are associated with the learners’ increased number sense. First, Wuzzit Trouble promoted mathematical proficiency by requiring learners to attend to several mathematical constraints at once. Second, the game engaged learners in an iterative process of decision-making by calling for students to try, check, and revise their strategy as they played.

scholarly journals MN-PGSOR Method for Solving Nonlinear Systems with Block Two-by-Two Complex Symmetric Jacobian Matrices

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Yu-Ye Feng ◽  
Qing-Biao Wu
Keyword(s):  
Nonlinear Systems ◽  
Iteration Method ◽  
Computing Time ◽  
Coefficient Matrix ◽  
New Method ◽  
Jacobian Matrices ◽  
Modified Newton Method ◽  
Preconditioned Matrix ◽  
Outer Iteration ◽  
Inner Iteration

For solving the large sparse linear systems with 2 × 2 block structure, the generalized successive overrelaxation (GSOR) iteration method is an efficient iteration method. Based on the GSOR method, the PGSOR method introduces a preconditioned matrix with a new parameter for the coefficient matrix which can enhance the efficiency. To solve the nonlinear systems in which the Jacobian matrices are complex and symmetric with the block two-by-two form, we try to use the PGSOR method as an inner iteration, with the help of the modified Newton method as an efficient outer iteration method. This new method is called the modified Newton-PGSOR (MN-PGSOR) method. Local convergence properties of the MN-PGSOR are analyzed under the Hölder condition. Finally, we give the comparison of our new method with some previous methods in the numerical results. The MN-PGSOR method is superior in both iteration steps and computing time.

scholarly journals Dynamic Cancellation: Selecting Time Warp Cancellation Strategies at Runtime

VLSI Design ◽  
1999 ◽  
Vol 9 (3) ◽  
pp. 237-251 ◽  
Author(s):  
Raghunandan Rajan ◽  
Radharamanan Radhakrishnan ◽  
Philip A. Wilsey
Keyword(s):  
Control Strategies ◽  
A Priori ◽  
Discrete Event ◽  
The Other ◽  
Performance Gain ◽  
Time Warp ◽  
Static Strategy ◽  
Parallel Discrete Event ◽  
Simulation Time

The performance of Time Warp parallel discrete event simulators can be affected by the cancellation strategy used to send anti-messages. Under aggressive cancellation, antimessage generation occurs immediately after a straggler message is detected. In contrast, lazy cancellation delays the sending of anti-messages until forward processing from a straggler message confirms that the premature computation did indeed generate an incorrect message. Previous studies have shown that neither approach is clearly superior to the other in all cases (even within the same application domain). Furthermore, no strategy exists to make a priori determination of the more favorable cancellation strategy. Most existing Time Warp systems merely provide a switch for the user to select the cancellation strategy employed. This paper explores the use of simulation time decision procedures to select cancellation strategies. The approach is termed Dynamic Cancellation and it assigns the capability for selecting cancellation strategies to the Logical Processes (LPs) in a Time Warp simulation. Thus, within a single parallel simulation both strategies may be employed by distinct LPs and even across the simulation lifetime of an LP. Empirical analysis using several control strategies show that dynamic cancellation always performs with the best static strategy and, in some cases, dynamic cancellation provides some nominal (5–10%) performance gain over the best static strategy.

scholarly journals LDPC Codes Based on α – Resolvable BIB and Group Divisible Designs

2021 ◽  
Author(s):  
Shyam Saurabh
Keyword(s):  
Block Design ◽  
Ldpc Codes ◽  
Ldpc Code ◽  
Finite Geometries ◽  
Group Divisible Designs ◽  
Tanner Graph ◽  
Group Divisible ◽  
Check Matrix ◽  
Balanced Incomplete Block ◽  
Resolvable Group

<p>Structured LDPC codes have been constructed using balanced incomplete block (BIB) designs, resolvable BIB designs, mutually orthogonal Latin rectangles, partial geometries, group divisible designs, resolvable group divisible designs and finite geometries. Here we have constructed LDPC codes from <i>α </i>–<b> </b>resolvable BIB and Group divisible designs. The sub–matrices of incidence matrix of such block design are used as a parity – check matrix of the code which satisfy row – column constraint. Here the girth of the proposed code is at least six and the corresponding LDPC code (or Tanner graph) is free of 4– cycles. </p>

scholarly journals On the JK Iterative Process in Banach Spaces

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Junaid Ahmad ◽  
Hüseyin Işık ◽  
Faeem Ali ◽  
Kifayat Ullah ◽  
Eskandar Ameer ◽  
...  
Keyword(s):  
Weak Convergence ◽  
Banach Spaces ◽  
Iterative Process ◽  
Iterative Scheme ◽  
Nonexpansive Mappings ◽  
The Other ◽  
Iterative Schemes ◽  
Strong And Weak Convergence ◽  
Nonexpansive Maps ◽  
Iterative Procedures

In the recent progress, different iterative procedures have been constructed in order to find the fixed point for a given self-map in an effective way. Among the other things, an effective iterative procedure called the JK iterative scheme was recently constructed and its strong and weak convergence was established for the class of Suzuki mappings in the setting of Banach spaces. The first purpose of this research is to obtain the strong and weak convergence of this scheme in the wider setting of generalized α -nonexpansive mappings. Secondly, by constructing an example of generalized α -nonexpansive maps which is not a Suzuki map, we show that the JK iterative scheme converges faster as compared the other iterative schemes. The presented results of this paper properly extend and improve the corresponding results of the literature.

The Research of LDPC Code in Communication System

2012 ◽  
Vol 532-533 ◽  
pp. 1135-1139
Author(s):  
Dan Hu
Keyword(s):  
Communication System ◽  
Channel Coding ◽  
Iterative Decoding ◽  
Storage System ◽  
Ldpc Codes ◽  
Ldpc Code ◽  
Optical Fiber Communication ◽  
Difficult Problem ◽  
Low Density ◽  
Channel Codes

Low-Density Parity-Check(LDPC) codes are a class of channel codes based on matrix encoding and iterative decoding. It has low decoding complexity as well as capacity approaching performance. Until now, the best designed LDPC codes can achieve the performance within only 0.0045dB of the Shannon limit. With the in-depth study, the encoding complexity of LDPC codes is not a difficult problem for application any more. Today, we can see LDPC codes widely used in many practical systems, such as wireless communication system, deep-space communication system, optical-fiber communication system and media storage system. This thesis first introduces the development of channel coding, and then the basic principles and concepts of LDPC codes. The following parts discuss several techniques of LDPC codes, including the construction methods of low-density parity matrix, the iterative decoding algorithms and performance analysis methods. Besides, we propose our opinions and our improved algorithms.

scholarly journals Design and Analysis of Non-Binary LDPC-CPM System for Hybrid Check Matrix Construction Algorithm of WSN

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2418 ◽  
Author(s):  
Jiahui Meng ◽  
Danfeng Zhao ◽  
Liang Zhang
Keyword(s):  
Error Correction ◽  
Channel Coding ◽  
Ldpc Code ◽  
Coefficient Matrix ◽  
Finite Domain ◽  
Triangular Structure ◽  
Check Matrix ◽  
Lower Triangular ◽  
Iterative Coding ◽  
Matrix Construction

In order to enhance the reliability and anti-interference performance of wireless sensor network (WSN) data transmission, this paper designs the low power scheme of the WSN from the angle of error correction coding and proposes the hybrid check matrix construction (HC) algorithm based on iterative coding algorithms with linear coding complexity. The algorithm first improves the traditional iterative coding algorithm, making it suitable for non-binary low-density parity check (LDPC) codes. Then, the algorithm applies the backward iteration method to change the coding scheme and uses the check matrix construction method so that the progressive edge growth (PEG) algorithm has a lower triangular structure, which is used as a base matrix. An improved quasi-cyclic LDPC (QC-LDPC) algorithm, with a lower triangular structure, is used to generate a cyclic shift matrix and a finite domain coefficient matrix. Simultaneously, the short loop is eliminated and the optimal check matrix is selected for use in the channel coding process. The non-binary LDPC-CPM system is modeled and simulated. The simulation results show that the non-binary LDPC code constructed by the HC algorithm not only has linear coding and storage complexity but also has strong error correction capability. The design of non-binary LDPC-CPM system parameters can enhance the reliability, anti-jamming capability and reduce the complexity and reduce the complexity of the WSN.

scholarly journals On the Design of Punctured Low Density Parity Check Codes for Variable Rate Systems

2017 ◽  
Vol 1 (2) ◽  
pp. 88 ◽  
Author(s):  
Marco Baldi ◽  
Franco Chiaraluce
Keyword(s):  
Ldpc Codes ◽  
The Other ◽  
Variable Rate ◽  
Parity Check ◽  
Pragmatic Approach ◽  
Parity Check Matrix ◽  
Tanner Graph ◽  
Low Density Parity Check ◽  
Check Matrix ◽  
Parity Check Codes

The authors face the problem of designing good LDPC codes for applications requiring variable, that is adaptive, rates. More precisely, the object of the paper is twofold. On one hand, we propose a deterministic (not random) procedureto construct good LDPC codes without constraints on the code dimension and rate. The method is based on the analysis and optimization of the local cycles length in the Tanner graph and gives the designer the chance to control complexity of the designed codes. On the other hand, we present a novel puncturing strategy which acts directly on the parity check matrix of the code, starting from the lowest rate needed, in order to allow the design of higher rate codes avoiding additional complexity of the co/decoding hardware. The efficiency of the proposed solution is tested through a number of numerical simulations. In particular, the puncturing strategy is applied for designing codes with rate variable between 0.715 and 0.906. The designed codes are used in conjunction with M-QAM constellations through a pragmatic approach that, however, yields very promising results.

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