International Journal of Electrical and Computer Engineering (IJECE) Vol. 8, No. 1, February 2018, pp. 622~630 ISSN: 2088-8708, DOI: 10.11591/ijece.v8i1.pp622-630  622 Journal homepage: http://iaescore.com/journals/index.php/IJECE Performances Concatenated LDPC based STBC-OFDM System and MRC Receivers Nejwa El Maammar 1 , Seddik Bri 2 , Jaouad Foshi 3 1,3 Electronics Instrumentation and Measurements, Faculty of Sciences and Technologies, Errachidia, Moulay Ismail University, Morocco 2 Material and Instrumentations: MIN, ESTM, Moulay Ismail University, Meknes, Morocco Article Info ABSTRACT Article history: Received Jul 17, 2017 Revised Dec 24, 2017 Accepted Jan 8, 2018 This paper presents the bit error rate performance of the low density parity check (LDPC) with the concatenation of convolutional channel coding based orthogonal frequency-division-multiplexing (OFDM) using space time block coded (STBC). The OFDM wireless communication system incorporates 3/4- rated convolutional encoder under various digital modulations (BPSK, QPSK and QAM) over an additative white gaussian noise (AWGN) and fading (Raleigh and Rician) channels. At the receiving section of the simulated system, Maximum Ratio combining (MRC) channel equalization technique has been implemented to extract transmitted symbols without enhancing noise power. Keyword: AWGN LDPC MRC OFDM STBC Copyright © 2018 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Nejwa El Maammar, Departement of Electronics, Instrumentation and Measurements, Faculty of sciences and technologies, Errachidia Moulay Ismail University, Morroco. Email:nejwa.elmaammar@gmail.com 1. INTRODUCTION The space-time block coding technique is considered one of the most attractive and representative multiple antenna techniques. It is also, an effective transmit diversity technique, was first proposed by Alamouti for flat fading channel [1]. Alamouti suggested a space time code for two transmit antennas, which provides a diversity gain and has a very simple decoder [2]. Space Time Block Codes (STBCs) have its application in cellular communications and wireless local area networks [3], and it‟s also the transmit diversity that has been studied extensively as a method of combating determine effects in wireless fading channel because of its relative simplicity of implementation and feasibility of having multiple antenna at the base station [4]. On the other hand, the Orthogonal Frequency Division Multiplexing is an efficient modulation technique used in certain wired and wireless application [5], it also is an attractive technology that is being implemented to achieve high bit data rate transmission invoked for high-bit-rate data transmission,especially in a highly dispersive multipath-fading environment that inflicts inter-symbol interference (ISI) by transforming a frequency selective fading channel into a set of parallel correlated fading channels [6]. In this context, the STBC-OFDM system may be one of most promising system configurations that can be adopted for 4th generation mobile systems. The combination of STBC and OFDM results in an enhanced system performance in wideband wireless channels [7]. Low Density Parity Check codes are a linear block codes were proposed by Gallager in 1962 [8], [9]. Owing to the codes‟ capability of approaching Shannon‟s performance limits, LDPC codes have been