In this paper, the application of regular Low-Density Parity-Check (LDPC) codes in Multi- Carrier Frequency-Hopping (MC-FH) CDMA systems is studied. To this end, different well known constructions of regular LDPC codes are considered and the Performance of LDPC coded MC-FH-CDMA systems, based on these constructions, are evaluated and compared in a frequency-selective slowly Rayleigh fading channel. These results are compared with those previously reported for super-orthogonal convolutionally coded MC-FH-CDMA systems. The simulation results indicate that the LDPC coded MC-FH-CDMA system significantly outperforms the uncoded and super-orthogonal convolutionally coded schemes. To alleviate the restrictions imposed by well known LDPC construction methods when applied to the coded MC-FH-CDMA system considered, a new semi-random construction is proposed and its Performance is evaluated in the coded scheme. The simulation results indicate that this new construction substantially outperforms other well-known construction methods in the application considered.

This study tested a model consisting of job satisfaction, organizational commitment, and job Performance as dependent variables, core self-Evaluations as independent variable, and perceived job characteristics, goal commitment, organizational climate, and organizational empowerment as mediators. Data were gathered from a sample of 294 employees (278 men, 16 women) of National Iranian South Oil Company in Ahvaz, Iran. The instruments used in present study consist of Core Self-Evaluations Scale (CSES), Organizational Commitment Scale (OCS), Job Performance Scale (GPS), Job in General Scale (JIGS), Organizational Climate Scale (OCS), Job Diagnostic Survey (JDS), Organizational Empowerment Scale (OES), and Goal Commitment Scale (GCS). Structural equation modeling (SEM) analyses indicated that the proposed model fit the data properly. The results also supported the direct effect of CSE on job satisfaction, organizational commitment and job Performance, and indirect effect of CSE on job satisfaction and organizational commitment through perceived job characteristics, organizational climate, and organizational empowerment. The relationship between CSE and job Performance was not mediated by goal commitment.