## 1 Introduction  
Significant throughput and reliability are considered basic requirements in the current era of communication. In the fifth generation (5G) and beyond 5G era, massive data storage, faster data processing, and 100% uptime availability are essential, for which mobile communication is the basic source of data transfer due to more mobility and less infrastructure. The success of any communication system depends on the channel through which it was transmitted. Due to multipath fading, degradation of the channel quality affects the system throughput and the reliability. Thus, it is necessary to improve the system reliability and throughput to fulfill the demand of the new era. Massive Multiple-Input Multiple-Output (mMIMO) systems are a wireless communication technology that use multiple antennas on both the transmitting and receiving sides. Through the utilization of this methodology, MIMO systems offer numerous benefits, such as enhanced capacity, enhanced reliability, and increased spectral efficiency [1; 2]. In the field of MIMO communications, three primary concepts can be identified: spatial multiplexing, transmit diversity, and spatial modulation [3]. Spatial multiplexingimplies the technique of concurrently transmitting numerous symbols from multiple pairs of antennas over a single-channel use [4]. Spatial multiplexing is utilized as an approach for enhancing both the data rate and the spectral efficiency of the system. On the other hand, transmit diversity refers to the simultaneous transmission of delayed and different versions of the symbols by various antennas, which is then equalized at the user equipment (UE) to provide diversity gain [5]. Lastly, Spatial Modulation (SM) is a cost-effective technology that activates a single Radio Frequency (RF) chain at the transmitter. SM utilizes the transmit antenna indexes as an additional information carrier [6]. The SM was introduced by [PERSON] et al. in [7; 8]. The improvement of data rate provided by MIMO systems comes at the expense of increased complexity, size, and higher hardware costs. In this paper, MIMO is used as transmit diversity and one antenna is used at the UE, so the MISO system is considered. In wireless communication systems, the utilization of Space-Time Block Code (STBC) is employed as an approach to improve the reliability and performance of data transmission over multiple antennas. The STBC protocol involves the distribution of data symbols across multiple transmit antennas, which are then transmitted over a specified period of time. This allows the receiver to take advantage of spatial diversity and effectively mitigates fading and multipath effects [9]. The Alamouti scheme was the first orthogonal STBC (OSTBC) to provide full transmit diversity for systems with two transmit antennas [10]. By utilizing orthogonal coding schemes like Alamouti coding, STBC ensures that the transmitted signals are decoupled at the receiver, enabling reliable detection and decoding. The receivers have the ability to detect multiple versions of the originally transmitted signal. This repetition of transmitted signals can significantly enhance the performance of the communication system. It leads to improved reception quality at the receivers. Additionally, the transmitting antennas will have a reduction on the overall power-transmission levels, leading to power enhancement at the transmitters. Furthermore, through cooperative communication operations, the radio system can effectively minimize the Bit Error Rate (BER). This, in turn, enhances the overall reliability of the system. Ensuring system reliability is of paramount importance in radio systems. STBC are orthogonal as originally introduced by [PERSON]. OSTBC is employed for simple, linear, and optimal decoding at the receiver. However, the existence of quasi-orthogonal STBC (QO-STBC) introduces inter-symbol interference (ISI). Intelligent Reflecting Surfaces (IRS) have emerged as a promising technology for enhancing wireless communication systems [11].