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The traditional analytical method greatly underestimates the throughput capability of the system in low beam density scenario, and cannot reveal the capacity saturation phenomenon in high beam density scenario.To overcome the preceding problems, a new system simulation method was proposed to accurately evaluated the capacity density indicator of satellite constellation network and integrated satellite and terrestrial network, Based on this method, first, the capacity density of different longitude and latitude regions of the earth was evaluated.It could be observed that the capacity density of the same region varies greatly with the movement of the satellite, and the maximum capacity density was twice the minimum.Then, areas with higher visibility usually had higher capacity density.In high-frequency scenarios, the impact of atmospheric attenuation on capacity density could not be ignored.Finally, for the integrated satellite and terrestrial network, the evaluation results showed that the capacity density of cellular coverage and satellite coverage could differ by four orders of magnitude.In order to improved the capacity density of satellite constellation network, two technical paths were attempted: increasing the maximum number of illuminated beams and increasing the satellite scale.The results showed that the performance was better when the constellation scale was increased when the total beams of the constellation were the same.However, the two ways to increase the total number of beams in a constellation had an upper bound on capacity, and the marginal effect decreased significantly.Finally, a scheme to increase the gain of satellite antenna was proposed.The simulation results showed that the proposed scheme could significantly increase the capacity density of constellation.

Low Earth orbit (LEO) mega-constellation satellite networks (LMCSNs) have shown great potential to extend the coverage capability of conventional terrestrial networks. The exploitation of the prevalent New Radio (NR) standard for LMCSNs can unleash the full potential toward a highly integrated satellite-terrestrial network. Despite this premise, how to systematically define, quantify, and assess the technical performance of NR enabled LMCSNs remains an open issue. In this paper, we address the challenging issue by proposing a holistic performance evaluation framework. Firstly, a key performance indicator (KPI) system including constellation-specific KPIs (i.e., $N$ -asset coverage, area traffic capacity, and service availability) and radio interface technology KPIs is devised. An efficient LEO constellation oriented performance assessment methodology is then carefully designed based on realistic beam layout and accurate interference modeling. We have carried out rigorous system-level simulations and provided extensive numerical results to assess the KPI system. It can be observed that the achieved area traffic capacity of the reference LEO constellation with 1800 satellites is less than 4 Kbps/km2. Besides, the $N$ -asset coverage and service availability range from 5.95 to 11.45, and from 24.9% to 32.7%, respectively.

With rapid development of satellite technology in monitoring the ocean, a good understanding of the physical processes involved in the electromagnetic ocean-surface interaction is required. The composite surface models are usually applied in the analysis of the interaction, hence a systematical check of their region of validity is desirable. Based on a generalized minimal residual procedure which is right preconditioned (GMRES-RP) that we have recently developed which has demonstrated the desirable properties of a numerical algorithm: robust and efficient, in this paper, for bistatic scattering from one dimensional ocean surfaces, we carry out a systematic assessment of the performance of the popular two-scale model and the advanced three-scale model under different conditions of ocean surface wind speeds, polarizations, frequencies, and incidence angles. It is found that the two-scale model in general captures the bistatic scattering pattern, yet the accuracy of geometrical optics (GO) for the large scale wave brings considerable impact on the overall accuracy. If the evaluation of the contribution of the large scale wave is instead using direct numerical integration for the corresponding Kirchhoff integral, impressive improvements are frequently observed, especially at low frequency (L and C bands) and low wind speed (3m/s). But care should be taken when apply two-scale method with numerical integration, since there are cases where visible discrepancy with method of moment (MoM) are observed. On the other hand, the three-scale model is found in very good agreement with MoM across the considered ocean surface wind speeds, polarizations, frequencies, and incidence angles, hence represents a much advanced model over the two-scale model. [ABSTRACT FROM AUTHOR]