## 1 Introduction  
The development of millimeter wave technologies has improved the functionality of wireless networks. It is now possible to meet the requirements for millimeter wave communication systems, such as high data rate, security, mobility, and spectral efficiency. In addition to increased system performance, success can be attributed to diversity approaches, wavelet transforms, coding algorithms, and other developing technologies. Future generations are considering wavelets because of their flexibility, which increases spectral efficiency. As the number of users for wireless communication quickly grows, many antennas are becoming utilized at the transmitter and receiver to maximize efficiency. MIMO antenna diversity is therefore essential for millimeter wave communication systems to boost capacity and minimize signal loss. The MIMO diversity technique was shown to outperform other diversity techniques when they were compared in for millimeter wave communication networks. Since millimeter  
and low energy consumption [1]. One of the key criteria for future wireless communication networks is an increase in spectral efficiency. The signal loss caused by channel propagation at the receiver is one of the current main research issues. When a system employs millimeter waves, the received signal becomes more sensitive since the frequency ranges from 3 GHz to 300 GHz. Discrete wavelet transforms are employed in orthogonal frequency division multiplexing (OFDM) systems to increase spectral efficiency (DWT). Therefore, wavelet transforms can be used to design antenna diversity techniques to enhance system performance and spectrum efficiency [2]. Different modulation methods enhance the performance of MIMO wireless channels. In MISO channels, transmit diversity is achieved using a sophisticated algorithm, whereas SIMO channels use receiver diversity schemes such as MRC and selection diversity [3; 4; 5; 6]. However, because it necessitates inserting a cyclic prefix at the transmitter and removing it at the receiver, conventional OFDM employing fast Fourier transform (FFT) still has the disadvantage of lowering spectral efficiency. As it does not require the use of a cyclic prefix, discrete wavelet transformations (DMTs) are employed as a substitute for FFTs to boost spectrum efficiency. One of the limitations of wireless signal transmission can be multipath fading, the result of which is that the signal at the receiver could be distorted and loud. Therefore, antenna diversity, or having several inputs and outputs, can enhance a receiver's BER performance. To increase spectral efficiency and decrease BER, MIMO diversity with wavelet transform must be applied in millimeter wave communication systems. The primary method for raising spectral efficiency and enhancing system performance in mobile communication is the use of smart antenna systems. In order to create required radiation patterns, smart antennas often consist of a number of radiating elements (i.e., array antennas) whose individual excitation can be controlled by a DSP (digital signal processor) [7]. In 5G wireless communication networks, antenna arrays are now a part of the default configuration. Since an antenna array contains several elements, it can be used as an MIMO system in wireless communications systems. By examining the redundancy across the several broadcast and receive channels, antenna arrays can be used to improve the performance of systems in terms of BER. They also enable a system's spatial data to be reused in order to increase coverage. The unlicensed spectrum at 60 GHz supports high rates, and many researchers are using the 60 GHz frequency because it also provides license free communication and improve efficiency [8; 9; 10; 11; 12]. Hence, for our investigation, the signal was deployed at 60 GHz and a two-element uniform array antenna array with half-length spacing was used to provide the MIMO diversity technique.