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Journal : Indonesian Journal of Electrical Engineering and Computer Science

A Model to Investigate Performance of Orthogonal Frequency Code Division Multiplexing Syafie, Nasaruddin; Melinda, Melinda; Fitria Sari, Ellsa
Indonesian Journal of Electrical Engineering and Computer Science Vol 10, No 3: July 2012
Publisher : Institute of Advanced Engineering and Science

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Abstract

OFCDM is an attractive multiple access scheme for high data rate application in Fourth-generation (4G) wireless communication system. Previously, several researches were only investigated the performance of OFCDM based on variable spreading factor. However, there are several system parameters may affected the performance of OFCDM. Therefore, this paper investigates the impact of several parameters on the performance system of OFCDMA over Rayleigh Fading channel as a realistic channel in wireless communications.The simulation system model of OFCDM is introduced. The computer simulation is developed by using MATLAB programming in order to show the impact of several parameters for OFCDM’s performance including number of carriers, size of symbol, symbol rate, bit rate, size of guard interval and spreading factor. The simulation results show that the higher number of carriers, larger size of symbol, higher symbol rate, higher bit rate and larger spreading factor are giving the better system’s performance in terms of Bit Error Rate (BER). However, the larger guard interval is giving the worst system’s performance.So all the parameters should be considered in the implementation of OFCDM for the 4G wireless communication system. DOI: http://dx.doi.org/10.11591/telkomnika.v10i3.621
Optimized Power Allocation for Cooperative Amplify-and-Forward with Convolutional Codes Nasaruddin, N; Melinda, M; Elizar, E
Indonesian Journal of Electrical Engineering and Computer Science Vol 12, No 8: August 2014
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v12.i8.pp6243-6253

Abstract

Future wireless communications technology should fulfill the demands of multimedia applications, interactive internet service, high data rates and power efficiency. However, wireless channel is affected by multipath fading that can degrade the system performance. To overcome the problem, cooperative communication has been introduced to be an efficient diversity technique to combat the multipath fading, to improve capacity and the system performance, and to reduce the energy comsumption by using power allocation technique in the network. This paper proposes an optimized power allocation (OPA) for cooperative amplify-and-forward (AF) protocol with convolutional codes (CC). A computer simulation model for the proposed system is developed using Matlab programming.  Then, performance of the system is evaluated in terms of the system throughput, bit error rate and amplification coeficient for power allocation. Furthermore, the different rates of CC are also considered in the network. Simulation results show that multi-relay AF network can provide a higher throughput and lower bit error rate. Moreover, the performance of OPA system is better than that of non-OPA system. The using lower rate of CC in the OPA system provides coding gain for multi-relay cooperative AF network. Finally, the different amplification coeficients among relays give a significant improvement to optimize the system performance.