High Altitude Platform Station Communication Research Articles

User Selection and Codebook Design for NOMA-Based High Altitude Platform Station (HAPS) Communications

High altitude platform station (HAPS) communications have made a tremendous impact on recent research into sixth-generation (6G) and beyond wireless networks. The large coverage area and significant computational capability of HAPS systems enable many areas of utilization in 6G and beyond applications, including Internet of Things (IoT) services, augmented reality, and connected autonomous vehicles. In addition, non-orthogonal multiple access (NOMA) is a cutting-edge technology that can be utilized to enhance spectral efficiency in HAPS systems. In this paper, we exploit NOMA-based HAPS communications and multiple antennas to meet the connectivity, reliability, and high-data-rate requirements of 6G and beyond applications. We propose a user selection and correlation-based user pairing algorithm for a NOMA-based multi-user HAPS system. Moreover, we investigate the codebook design for HAPS communication and adapt the polar-cap codebook (PCC) to the HAPS channel which shows Rician fading propagation characteristics dominated by the line-of-sight (LOS) component. Performance evaluations show that the proposed user selection algorithm is perfectly suited to the HAPS channel and that the PCC provides a remarkable spectral efficiency.

Efficiency Evaluations Based on Artificial Intelligence for 5G Massive MIMO Communication Systems on High-Altitude Platform Stations

The key technologies for applying fifth generation in high-altitude platform station (HAPS) communication systems have many outstanding advantages, especially large-scale antenna array technology. HAPS communication systems have inherent advantages that can perfectly complement large-scale array antenna technology and solve the problems of many existing ground communication systems. The chances of long-packet data users and short-packet data users being serviced are different due to the differing data length of each user's packet. According to the user's channel environment and data length, the user with the smallest delay is selected for transmission. Dynamic and interdependent characteristics between systems and the evaluation of the efficiency of wireless resources are studied in this article. Game theory is applied to the evaluation of the wireless resource efficiency of the system, and an efficiency evaluation model is constructed. In addition, the efficiency of this preliminary work is verified by simulation.

Multi-beam coverage and beamforming technology for high altitude platform station communication system

Multi-beam antenna technology can effectively mitigate the impact of deep fading caused by multipath propagation on communication quality through spatial diversity and increase the reliability of wireless mobile communication systems. At the same time, the multi-beam antenna with beamforming algorithm as the key technology can realize spatial division multiple access (SDMA) by automatically adapting the weight vector of the antenna array, enhance the expected value, and suppress the interference. A novel beamforming technology increases the inner circle beam width and reduces the outer ring beam width to minimize the difference between the internal and external cell link SNR. This study considers reducing the number of cells by reasonably allocating beams, which satisfies both the requirements of coverage link quality and the difficulty of forming antenna beams. This research subject applies the scheme and strategy of improving multi-beam antenna technology in the same system. Under the requirement of cell coverage and partitioning, the related technologies and strategies combining multi-beamforming technology and space-time block code technology can obtain high coding gain and diversity gain without sacrificing bandwidth and effectivelyx improve the wireless systematic capacity.

Time-Varying Communication Channel High Altitude Platform Station Link Budget and Channel Modeling

Because of the high BER (Bit Error Rate), low time delay and low channel transmission efficiency of HAPS (High Altitude Platform Station) in the near space. The link budget of HAPS and channel model are proposed in this paper. According to the channel characteristic, the channel model is set up, combined with different CNR (Carrier Noise Ratio), elevation angle, coding situations of wireless communication link by using Hamming code, PSK (Pulse Shift Keying) and Golay code respectively, then the situations of link quality and BER are analyzed. The simulation results show that the established model of the link budget and channel are suitable for the theoretical analysis results. The elevation of the HAPS communication link is smaller while the BER is increasing. The case of channel in the coding is better than in the un-coded situation. When every bit power and thermal noise power spectral density is larger, the BER of the HAPS communication link is becoming smaller.

A Reinforcement Learning Approach to Call Admission Control in HAPS Communication System

The large changing of link capacity and number of users caused by the movement of both platform and users in communication system based on high altitude platform station (HAPS) will resulting in high dropping rate of handover and reduce resource utilization. In order to solve these problems, this paper proposes an adaptive call admission control strategy based on reinforcement learning approach. The goal of this strategy is to maximize long-term gains of system, with the introduction of cross-layer interaction and the service downgraded. In order to access different traffics adaptively, the access utility of handover traffics and new call traffics is designed in different state of communication system. Numerical simulation result shows that the proposed call admission control strategy can enhance bandwidth resource utilization and the performances of handover traffics.

A Novel Method of High Dynamic Carrier Acquisition and Track for HAPS Communication Networks

To detect and receive the high dynamic and high information-rate signal for high altitude platform station(HAPS) in the stratosphere, it is necessary to design digital system to acquire and track the carrier. In the high dynamic and high information-rate situation, the most important aspect is the great influence of Doppler frequency shift and high information rate on the carrier acquisition and track. Carrier acquisition and track in the high dynamic and high information-rate situation was implemented by means of the combination of FPGA and frequency, phase lock loop. A new algorithm using DQPSK for carrier acquisition and track was proposed and the validity of the design and algorithm was proved by means of trials and comparison with EKF method in the high dynamic and high information-rate situation.