Journal of University of Duhok, Vol. 32, No.1 (Pure and Eng. Sciences), Pp 159-171, 3232 ahmad.al-khalil@uod.ac 159 PERFORMANCE IMPROVEMENT OF BER BASED ON MULTIPATH FORWARD ERROR CORRECTION DIVERSITY IN WIRELESS COMMUNICATION CHANNELS AHMAD BAHEEJ AL-KHALIL Dept. of Computer Science, College of Science, University of Duhok, Kurdistan Region, Iraq (Received: April 28, 2020; Accepted for Publication: June 14, 2020) ABSTRACT The multipath phenomenon is a major factor that is continually affected negatively the performance of wireless communication systems. Since the receiver gets different copies of the transmitted signal from various paths at different times. Consequently, destructive or constructive interference can occur. Therefore, the performance of wireless communication systems is poor in term of bit error rate. This phenomenon can be taken as an advantage if the multiple – input – multiple – output antenna systems are employed at both transmitter and receiver sides (antenna diversity) to improve the bit error rate performance. This paper focuses on the combination of multipath forward error correction diversity technique with vertical-Bell laboratories layered space-time coding. This will lead to enhance the bit error rate in wireless communication systems. The proposed system used Rayleigh and additive white Gaussian noise as two different channel models. The multipath forward error correction diversity technique treats the multipath propagated signals as unessential copies, to utilise them to enhance the bit error rate limitation in the multiple – input – multiple – output systems. The simulation results showed that the performance of the proposed system can be gradually improved by increasing the number of utilised multipath signals in the multipath forward error correction diversity technique. KEY WORDS: FEC, Diversity, BER, Multipath, CWMC, MIMO, V-BLAST, Rayleigh, AWGN. 1. INTRODUCTION t present, there is a noticeable achievement in the development of wireless communication systems field. This development requires more efforts to provide high communication reliability and improving the data rate (Seferagić et al. 2020). Subsequently, challenges in the industry of communication are presented especially in enhancing the performance of the wireless communication system in term of quantity and quality (Farzamnia et al. 2019). In wireless communication, the transmitted signals propagate via a wireless channel. These signals can face a certain level of fading such as shadowing, diffraction, reflection and noise. Furthermore, the recipient will get a direct copy (the original copy) of the transmitted signal Line – of - Sight (LoS) path in addition to the other copies that arrived from different paths Non – Line – of – Sight (NLoS) at a slightly different time (Jakborvornphan 2019). As a result, a signal distortion or disruption and errors will have occurred, and the original signal cannot be retrieved at the receiver. Diversity is one of the approaches used to combat the effect of fading in wireless communication systems (Khatoon and Chidar 2019). Diversity is a powerful and effective technique which can overcome the multipath fading channel effect and avoiding error bursts (O. A et al. 2014). The idea of the diversity techniques is to provide the receiver by uncorrelated faded replicas of LoS signal. After that, two or more copies of the received signal are combined to raise the overall Signal – to – Noise – Ratio (SNR). Diversity can be produced and represented by several ways such as space diversity, time diversity, frequency diversity, polarisation diversity and angle diversity. Moreover, different diversity techniques can be combined to enhance the reliability and the performance of the wireless communication systems (Anbarasi et al. 2017). For instance, antenna diversity can be concatenated with time diversity that can be obtained by channel coding. This paper is structured as follows: section (2) covers the related work, while the principles of diversity is explained in section (3). Section (4) demonstrates the proposed diversity method. While section (5) presents the research A