Medical-care Internet of Things enables rapid medical assistance by providing comprehensive and clear healthy information. However, due to the limited infrastructure, it is difficult to quickly and securely transmit medical-care information in poverty-stricken or disaster-stricken areas. To tackle the above situation, in this article, we propose a delay-sensitive secure nonorthogonal multiple access (NOMA) transmission scheme with the high-altitude platform (HAP) and low-altitude platforms (LAPs) cooperated to securely provide delay-sensitive medical-care services. In the proposed scheme, we first design a novel HAP–LAP secure transmission framework to provide NOMA communication services to multiple hotspots. Constrained by the limited power and spectrum, we formulate an optimization problem, such that the privacy information delay is minimized. For thisnonconvex optimization problem, we design an alternating optimization framework, where the power, spectrum, and LAPs’ location are tackled in turn. In addition, we theoretically analyze the performance superiority compared with the orthogonal multiple access scheme and derive the secrecy outage probability closed-form expression. Finally, numerical results show the performance superiority of the proposed scheme compared with the current works with respect to the secure information delay. 

Delay-Sensitive Secure NOMA Transmission for Hierarchical HAP–LAP Medical-Care IoT Networks

The sixth generation (6G) communication creates a fully connected world of terrestrial wireless and satellite communications, which achieves global seamless coverage. To obtain the tripartite balance of spectrum efficiency, system throughput and complexity at the receiving end, clustered-NOMA (C-NOMA) is recommended. With Low Altitude Platform Station (LAPS) like UAV for strengthening communication in certain areas, and High Altitude Platform Station (HAPS) for ensuring wide coverage, we put forward the XAPS-enabled (including one HAPS and multiple UAVs) C-NOMA system in 6G heterogeneous Internet of things and investigate the joint 3D-location planning and resource allocation problem by optimizing four factors systematically, which are the spectrum allocation, power control, horizontal coordinate and hovering altitude optimization of UAVs to maximize the overall system uplink achievable sum rate. Due to the strong coupling among these factors, it is a mixed integer nonlinear programming (MINLP) problem, which is extremely difficult to solve. Therefore, we decompose it and propose a two-stage solution. Specifically, in the first stage we transfer resource allocation problem into a many-to-one spectrum matching game coupled with power control, where UAVs and subchannels are two groups of participants. Then we complete the second stage by optimizing UAVs’ 3D-locations, including horizontal coordinates and hovering altitudes. Finally, we repeat these two stages iteratively until the near-optimal result is obtained. Both theoretical analysis and simulations show that our proposed approach outperforms previous solutions in terms of system uplink sum rate with relatively low complexity.

Joint 3D-Location Planning and Resource Allocation for XAPS-Enabled C-NOMA in 6G Heterogeneous Internet of Things

Convergence of Broadband and Broadcast/Multicast in Maritime Information Networks

Quantum information and communication technology will lead us to the new era of ultra-fast and absolute-secure networks. With the emergence of quantum supremacy on the horizon, the security of various classical encryption systems soon may be deemed obsolete. As a remedy, quantum key distribution (QKD) is proposed as a novel quantum-based secret keys exchange, which is developed to solve the problems of legacy encryption. It is anticipated that QKD will provide stronger security for future communication systems even in the presence of malicious quantum attacks. As the QKD research and development is getting mature, the theoretical use cases of QKD in various industries are proliferating. In this treatise, we summarise the potential applications of QKD for future communication technology while highlighting the ongoing standardisation efforts essential for the sustainability and reliability of the near-future deployment. Additionally, we also present the various challenges faced by both discrete variable and continuous variable QKD schemes hindering their widespread implementation into our future communication networks. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1049/qtc2.12044

Towards the industrialisation of quantum key distribution in communication networks: A short survey

The space–air–ground integrated network (SAGIN)-related issues are attractive in the sixth generation (6G) technologies, which facilitate the global coverage and seamless service. The cooperation of high altitude platforms (HAPs) and low-Earth orbit (LEO) satellites provides the remote area users with comprehensive coverage and service. In this work, we consider the cooperation of HAPs and LEO satellites in SAGIN to serve terrestrial users in the remote area for data collection and transmission. To deal with the periodical motion of LEO satellites, we employ the time expanding graph (TEG) to represent the multiple resources in SAGIN and depict task flow transmission processes. Based on TEG, we aim to maximize the total data received by the ground data processing center in a time horizon, considering multiple resource constraints and flow restrictions. The original problem is formulated in the form of mixed-integer linear programming, which is intractable to obtain the optimal solution by brute-force searching. To alleviate this intractability, we propose the Benders decomposition-based algorithm to obtain the optimal solution within an acceptable time complexity via iterations between the master problem and subproblem. Moreover, to further expedite the solution in large-scale systems, an acceleration algorithm is proposed by handling the master problem with an approximation algorithm and the subproblem with a unit-flow-based algorithm. Finally, simulations are conducted and the numerical results verify the efficiency of the proposed algorithms, and the effects of various network parameters are analyzed as well. 

Toward Data Collection and Transmission in 6G Space–Air–Ground Integrated Networks: Cooperative HAP and LEO Satellite Schemes

High Altitude Platform (HAP) systems comprise airborne base stations deployed above 20 km and below 50 km to provide wireless access to devices in large areas. In this paper, two types of applications using HAP systems: one with HAP Station (HAPS) and the other with HAPS as International Mobile Telecommunication (IMT) Base Station (HIBS) are introduced. The HAP system with HAPS has already received wide recognition from the academia and the industry and is considered as an effective solution to provide internet access between fixed points in suburban and rural areas as well as emergencies. HAP systems with HIBS to serve IMT user terminal have just started to draw attention from researchers. The HIBS application is expected to be an anticipate mobile service application complementing the IMT requirement for cell phone or other mobile user terminals in which the service field of HAPS application cannot reach. After describing and characterizing the two types of systems, coexistence studies and simulation results using both the Power Fluxed Density (PFD) mask and separation distance based methods are presented in this paper. This paper also predicts future trends of the evolution paths for the HAP systems along with challenges and possible solutions from the standpoint of system architectures and spectrum regulation.

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Sheng Gao

Papers

Overview of development and regulatory aspects of high altitude platform system