This paper analyzes and solves the optimization problem of the performance of a multi-antenna unmanned aerial vehicle (UAV)-aided NOMA multi-user pairing system. Based on the approximation of the Gaussian-Chebyshev quadrature and incomplete Gamma function, we successfully derive the exact and asymptotic closed-form expressions for the block error rate, throughput, and goodput of the system. Moreover, we also provide other metrics such as the latency, reliability, and age of information (AoI). The results indicate that the considered system meets the requirements of ultra-reliable and low-latency communications (URLLC). Particularly, its reliability is higher than 99.99% and latency is less than 1 ms. The optimization of the UAV's altitude, block length, and the number of transmission bits to maximize the throughput and minimize the latency and AoI of the considered system is also studied by using iterative algorithms. Furthermore, we propose an algorithm to optimize the transmission power of UAVs to maximize the system's energy efficiency. The greedy algorithm is used to schedule paired users and achieves better performance compared to the random schedule. Moreover, applying multiple antennas and maximum ratio transmission can significantly improve the latency and AoI performance of the considered system. The accuracy of analytical frameworks is verified by simulation results.

In this work, we consider a base station (BS) mounted on an unmanned aerial vehicle (UAV) called as an aerial BS (ABS). The ABS is equipped with multiple antennas to assist two pairs of users in nonorthogonal multiple access (NOMA) scheme, and it serves as a relay station to forward the data from the uplink to the downlink of ground IoT users in half-duplex mode. Moreover, the communication power of ABS is harvested from ambient radio-frequency (RF) sources, such as television (TV) and radio signals via the time switching mechanism. In order to improve the efficiency of harvested energy, multiple antennas at the TV/radio tower and the maximal-ratio transmission (MRT) scheme are applied. The proposed ABS RF energy harvesting system overcomes the problem of connectivity of ground IoT users and the energy limitation of devices. The system performance is evaluated in terms of the outage probability of each pair of IoT users in various urban communication environments. Monte Carlo simulation results are provided to validate the accuracy of the developed analytical results and also demonstrate the performance of the proposed system. The results show that the proposed system achieves better performance than that of benchmark systems and the performance can be improved significantly by adjusting the UAV’s altitude.

In this study, a dual‐hop cooperative communication system with radio frequency (RF) energy harvesting was investigated in two cases of linear and non‐linear energy harvesting models. In the proposed system, the signal is transmitted directly from a source node to a destination node or sent with support of selected relay nodes. While both the source node and the destination node are powered normally, the relay nodes are powered by harvesting technique. To choose the best relay node, a selection combination method was applied at the destination node in both cases of amplify‐and‐forward and decode‐and‐forward protocols. To evaluate the system performance, the outage probability of the cooperative communications over independent identically distributed Nakagami‐ m was derived and analysed with arbitrary m parameter whereas this parameter was fixed to be integral value in previous research studies. Furthermore, the approximate and asymptotic operations are applied to simplify the outage probability expressions. The simulation program was developed based on the Monte Carlo method and MATLAB software with two aims of evaluating the system performance and verifying the theoretical results. The simulation results demonstrate that the analysis and evaluation of the study are considerably accurate.

Water-filling methods is one of techniques to improve a performance of multiple input multiple output (MIMO) system. However, the application of water-filling method to multiple hops MIMO relay system hasn't been discussed, especially in amplify and forward scheme. In this paper, the water-filling method for multiple hops MIMO relay system with amplify and forward scheme is proposed and evaluated in both perfect channel state information (CSI) and imperfect CSI. The effect of imperfect CSI on water-filling and on co-channel interference is taken into account. Compared to average transmit power, the end-to-end channel capacity of proposed water-filling method is higher in perfect CSI, however, it is subject to the effect of imperfect CSI. Additionally, a half duplex and a full duplex transmission method are also discussed in this paper. The end-to-end channel capacity of full duplex is higher and more robust than that of half duplex due to a double of allocation time and a half of delay time.

Due to rapidly increasing of elderly population all over the world and quickly developing of entertainment devices, wireless body area network (WBAN) attracts attention. For both medical and non-medical applications, a reliability, high energy-efficiency and high throughput of WBAN communication are requested. The well-known cluster-based is proposed to obtain the high energy-efficiency, however the transmission in every cluster is controlled on MAC layer by superframe in order to obtain the high throughput. The performance of original cluster-based, complete control and spatial reuse superframe scenarios is analyzed and compared. The calculation result indicates that the spatial reuse superframe outperforms the original cluster-based when the access probability and/or the total number of sensors are high. Furthermore, there are the optimal number of clusters, the access probabilities and the total number of sensors that achieve the highest throughput. The optimization method of number of spatial reuse superframe (k) is proposed to obtain the highest throughput when another factors change. k increases when another factors of system model increase, excepted the payload. The optimization method of another factors is similar and the proposed method can be applied to not only IEEE802.15.6 WBAN but also another cluster-based wireless sensor networks.

A frame-patch matching based robust video watermarking using KAZE feature is proposed in this paper. We employed the KAZE feature for matching the feature points of frame-patch with those of all frames in video. In our method, the watermark information is embedded in Discrete Cosine Transform (DCT) domain of randomly generated blocks in the matched region. In the extraction process, we synchronized the embedded region from the distorted video by using KAZE feature matching. RST (rotation, scaling, translation) parameters are estimated and the watermark information can be extracted. Experimental results showed that our proposed method is very robust against geometrical attacks, video processing attacks, temporal attacks, and so on.

For high end-to-end channel capacity, the amplify-and-forward scheme multiple-hop MIMO relays system is considered. The distance between each transceiver and the transmit power of each relay node are optimized to prevent some relays from being the bottleneck and guarantee the high end-to-end channel capacity. By proposing the transmission environment coefficient, the path loss is described in a new way and then the distance of multiple-hop relay system can be optimized more simply than the original one. However, when the system has no control on Mac layer, the performance of system is deteriorated because of the presenting of interference signal. Thus the specific control protocol on MAC layer for multiple-hop system is proposed to reduce the power of interference signal and obtain the high end-to-end channel capacity. According to proposed control protocol on MAC layer, the system indicates the trade-off between the end-to-end channel capacity and the delay time.

Multiple-input multiple-output (MIMO) is known as an one of the most attractive candidates for large capacity. However, when signal to noise ratio (SNR) is decreased, the propagation character of MIMO is dropped rapidly. For re- maining the propagation character of MIMO and/or increasing a capacity, MIMO repeater systems have been discussed. In MIMO multi repeater system, called distributed MIMO repeater system, to obtain bound of capacity of two-way repeater system, we propose a simple mathematical method and statistical Markov chain Monte Carlo method for optimizing distances and transmit power simultaneously.

Multiple-input multiple-output (MIMO) repeater systems have been discussed in several published papers. When a repeater has only one antenna element, the propagation environment is called keyhole. In this kind of scenario an achievable channel capacity and a link quality are decreased. Another limit is when the number of the antenna element of a repeater is larger than the one of a MIMO transceiver, the channel capacity cannot be increased. In this paper, to obtain an upper bound of the channel capacity, we express a propagation process of the distributed MIMO repeater system with decode-and-forward method by the numerical formula, and optimize the position of each repeater.