In this paper, we introduce an intelligent reflecting surface (IRS)-assisted wireless powered heterogeneous network (WPHN) consisting of two heterogeneous groups of devices. Specifically, one group of devices, i.e., energy-harvesting devices (EHDs), are charged by external energy supplies, while the other group of devices, i.e., non-energy-harvesting devices (NEHDs), are powered by internal energy supplies. An IRS aims to participate in the wireless energy transfer (WET) in downlink and the wireless information transfer (WIT) in the uplink. A sum throughput maximization problem is formulated subject to the constraints of individual energy consumption, transmission time scheduling, and IRS phase shifts. To cope with the non-convexity of the problem, we first derive the optimal IRS phase shifts of the uplink WIT independently. Next, the semi-definite programming (SDP) relaxation is adopted to recast this non-convex problem into the convex one, which can be numerically solved. Then, a novel low-complexity scheme is developed to gain more insights and mitigate the computational complexity induced by the SDP relaxation. In particular, the dual problem and Karush-Kuhn-Tucker conditions are first utilized to obtain the optimal transmission time scheduling. Then, we propose a method based on Riemannian manifold optimization to compute the optimal IRS phase shifts of the downlink WET in closed-form. Finally, simulation results are presented to verify the optimality of our proposed scheme, and highlight the benefits induced by the IRS to coordinate these heterogeneous devices.

To tackle the address aggregation problem for Low Earth Orbit (LEO) satellite communication system, a global geographical Internet Protocol (IP) subnet division model for space-ground integrated network addressing scheme is proposed in this paper. A two-dimensional spherical coordinate system based on spherical distance is applied to describe the LEO satellite track and the location information of geographical subnet zone. A mathematical framework for abnormal addressing users is constructed under the system. The size and division of geographical zone influence the expectation of abnormal user number through the ratio of logically covered and fully covered time. When the terrestrial regions are divided into small cells, the number of abnormal users reduces, as well as the partial routing cost. The simulation results confirm that the ratio of logically covered and fully covered time increase and the number of abnormal users decreases when the size of ground cells declines. The origin regions could be divided into smaller ground cells in order to reduce abnormal addressing users, balancing the cost on partial routing mechanism, mobility management, and satellite routing table items. The work presented a solution and direction of addressing scheme and mobility management design for the space-terrestrial hybrid network.

Due to the global coverage and real-time access advantages of the Tracking and Data Relay Satellite System (TDRSS), the demonstration platform based on TDRSS can satisfy the new technology verification and demonstration needs of the space information network (evolution from sensorweb). However, the comprehensive evaluation research of this demonstration platform faces many problems: complicated and diverse technical indicators in various areas, coupling redundancy between indicators, difficulty in establishing the number of indicator system layers, and evaluation errors causing by subjective scoring. Concerning the difficulties, this paper gives a method to construct this special index system, and improves the consistency of evaluation results with Analytic Hierarchy Process in Group Decision-Making (AHP-GDM). A comprehensive evaluation index system including five criterions, 11 elements, more than 30 indicators is constructed according to the three-step strategy of initial set classification, hierarchical optimization, and de-redundancy. For the inconsistent scoring of AHP-GDM, a high-speed convergence consistency improvement strategy is proposed in this paper. Moreover, a method for generating a comprehensive judgment matrix (the aggregation of each judgment matrix) aggregation coefficient is provided. Numerical experiments show that this strategy effectively improves the consistency of the comprehensive judgment matrix. Finally, taking the evaluation of TDRSS development as an example, the versatility and feasibility of the new evaluation strategy are demonstrated.

Given that L-band digital aeronautical communications system type 1 (LDACS1) may share the same spectrum with the legacy Distance Measuring Equipment (DME) system, DME, impulsive interference would be the main issue of this aeronautical communications system. To improve the performance of the LDACS1, a time-domain Correlative Interference Mitigation (CIM) aiming at DME impulse is proposed in this paper. This proposed method could be expected to detect and mitigate the DME interference by utilizing strong auto-correlation of DME signals and weak cross-correlation with LDACS1 signals. In CIM, correlative analysis and time-domain filtering is applied to obtain the information instead of preset thresholds, which is different from the existed impulsive interference mitigation method, i.e., Pulse Blanking (PB). Simulation results illustrate that CIM effectively improves the Bit Error Rate (BER) performance and achieves lower BER compared with PB. Furthermore, CIM can maintain its stability and effectiveness in certain transmission rates and power levels of DME pulse pairs.