# Optimization for an Indoor 6G Simultaneous Wireless Information and Power Transfer System
## 1 Introduction  
The 6G science and technology has developed very rapidly in recent years in order to improve the strength of transmitted and received signals, as well as system performance gain. Therefore, symmetric antenna arrays are widely used in communication, radar, and other systems. The focus of 6G communication is on four application areas: solving social problems, connecting people and things, building a broader communication environment, and achieving the complex integration of the virtual and the real [1; 2; 3; 4]. The transmission capacity of 6G is probably 100 times higher than that of 5G, while the network latency is also reduced from milliseconds (1 ms) to microseconds (100 \(\upmu\)s). The main purpose is to develop the internet. Power efficiency, spectral efficiency, air delay, connection density, reliability, peak data rate, and user experience data rate are far better than those of 5G mobile communication systems, which have been officially rolled out all over the world [5; 6; 7]. As 6G communication systems are being actively developed, in order to meet the goal of high-speed communication, the US Federal Communications Commission (FCC) suggests that the frequency band used for 6G should be 95 GHz to 3 THz. As 6G has higher speed, lower latency, and a wider connection range than 5G, more high-frequency resources such as millimeter and terahertz waves can be implemented with artificial intelligence technology to create more connections. Energy-constrained and energy-consumptive are typical wireless device problems in the Internet of Things (IoT), although the wireless device can solve them by changing batteries [8; 9]. However, it requires high operational costs, and is not feasible in some scenarios. WPT and SWIPT can solve this problem by replenishing energy from the ambient environment constantly. Moreover, the SWIPT can provide energy and transfer data at the same time. For some applications, the sensor can use the relay wireless signal or the base station wireless signal to harvest power when it has information transaction requirements. In the past, some studies on low-power IoT have used UAVs to improve the SWIPT/WPT charging efficiency and extend the transmission path of the base station [10]. There are also studies on the coverage and performance improvement of systems using SWIPT/WPT relays [11]. Some researchers have used deep learning methods to adjust the antenna for the SWIPT system [12; 13]. SWIPT cooperative spectrum sharing for 6G-enabled cognitive IoT networks was proposed in [14]. SWIPT cooperative relays were discussed in [11]. Simultaneous WPT with IoT toward 6G has been presented in [15]. For THz beamforming in 6G communication systems, [PERSON] used a reconfigurable intelligible surface for beaming [16]. [PERSON] applied deep reinforcement learning to adjust a reconfigurable intelligent surface to improve the beaming technology [17]. [PERSON] employed circuit multiple beaming networks to reduce the cost and power consumption [18]. [PERSON] proposed a mitigation method for adversarial attacks against 6G machine learning models for millimeter-wave beam prediction using adversarial training. The results show that the mean square errors of the defended model under attack are very close to those of the undefended model without attack [19]. Some studies on beamforming technology for SWIPT and WPT have been published in recent years [20; 21; 22; 23; 24]. The topologies for splitting-based SWIPT are investigated in [25; 26; 27]. Time-splitting, power-splitting, and frequency-splitting are the most popular ways to achieve SWIPT. In the power-splitting technique, a power-divided component is utilized to divide the received signal into two streams with a designed power ratio. The major merit is that the signal is used for both functions in the same time slot. For the evolution algorithm, Differential Evolution (DA) and SADDE have been used in the antenna beamforming design, as in [17; 28].