## 2 Related Works
### Beamforming  
For optimal beamforming, position and orientation computation of MIMO is important. Estimating the position and orientation of 5G systems was established through the millimeter wave MIMO [35]. mmWave signals and massive MIMO systems are the future enabling technologies such as 5G networks. 5G networks provide high data rate communication, and potential advantages for accurate positioning are largely undiscovered. Here, the novel two-stage algorithm is introduced for position and rotation angle estimation. This algorithm is based on the multiple measurement vectors matching pursuit for coarse estimation, and the refinement stage is based on the space alternating generalized expectation maximization algorithm. However, position estimation in two-dimension (2D) is inaccurate since three-dimensional (3D) estimation provides a more accurate position of SU. A low complex hybrid beamforming and precoding processor is presented for 16 \(\times\) 8 2D planar antenna array in mmWave system [36]. In this work, antenna selection is performed using a Maximum Ratio Combining (MRC) algorithm, which reduces the RF chains and baseband processing complexity. The optimal SVD precoder is used to select a basis vector with the highest correlation. The searching complexity is reduced using a slide window index selection-MIB-SOMP algorithm. Therefore, searching complexity is reduced, and hardware efficiency is increased to the original algorithm. At last, the proposed algorithm was implemented and designed using 90 nm CMOS technology. Usage of a 2D planar array limits the coverage of the massive MIMO to 120\({}^{\circ}\) sector in the azimuth angle. Beamforming and security are assured jointly with the use of Artificial Noise (AN) [37]. To improve the security of the secondary network, AN is used to mask the transmitting beamforming. In this, AN-aided transmit power of the information signal is minimized under secrecy rate constraint, harvested energy constraint and the total transmit power. To achieve secure transmission, the secondary transmitter employs transmit beamforming with AN, which acts as interference to the eavesdroppers and provides energy to the secondary users. To achieve the perfect Channel State Information (CSI), this paper proposes the Successive Convex Approximation (SCA) algorithm, which is an iterative algorithm. The addition of AN not only assures security but also degrades the signal quality, which is ineffectual in the secondary network. For antenna arrays with odd symmetry, two adaptive filtering algorithms are presented in [38]. Adaptive antenna arrays with the proposed algorithms perform better in steady-state while decreasing computational complexity. Beamforming is performed in massive MIMO using a hybrid combination of analog and digital beamforming [39]. This process mitigates the problems of complexity and power consumption which are serious in higher super frequency and extremely high-frequency bands. This method evaluates the performance of the nonlinear block multi-diagonal precoding, an intermediate solution between the conventional linear precoder and nonlinear precoder over an analog and digital hybrid beamforming constitution. The involvement of 2D beamforming limits the coverage of MIMO, which affects the beamforming performance. Beamforming is performed using the angular-based and power allocation framework in mmWave massive MIMO systems [40]. Many beamforming and power allocation schemes emerged to leverage the mmWave channel characteristics to enhance the sum capacity and coverage of multi-user transmissions. In this process, angular-based beamforming is used which requires the direction of arrival and direction of departure of the propagation channel. This method relies on the estimation of leakage caused by each user equipment (UE) on all other UEs from the Direction of Arrival (DoA) contributions. Here, angular-based beamforming is proposed in which the line of sight (LOS) channel is used.