With the growing demand, Wireless Multimedia Sensor Networks (WMSNs) play an increasingly important role, which enhances the capacity of typical Wireless Sensor Networks (WSNs). Additionally, integrating satellite systems into WMSNs brings about the beneficial synergy, especially in rural and sparsely populated areas. However, the available spectrum resource is scarce, which contradicts the high-speed content required for multimedia. Cognitive radio is a promising solution to address the conflict. In this context, we propose a novel spectrum-sharing method for the integrated wireless multimedia sensor and cognitive satellite network based on the dynamic frequency allocation. Specifically, the Low Earth Orbit (LEO) satellite system plays the role of the auxiliary to connect sensor nodes and the remote control host, and it shares the same frequency with the Geostationary Earth Orbit (GEO) system in the downlink. Because the altitudes of GEO and LEO satellites differ greatly, the beam size of GEO is much larger than that of LEO, which provides the opportunity for LEO beam to reuse the frequency that was allocated to the GEO beam. A keep-out region is defined to guarantee the spectral coexistence based on the interference analysis in the worst case. In addition, a dynamic frequency allocation algorithm is presented to deal with the dynamic configuration caused by the satellite motion. Numerical results demonstrate that the dynamic spectrum-sharing method can improve the throughput.

Luby Transform (LT) codes play an important role in both data transmission and storage, but it is still a challenging problem that how to analyze their performance due to the degree distributions. In this letter, a novel methodology to analyze the performance of LT codes is proposed. This method establishes a probability transfer model between two adjacent steps of the belief propagation decoding algorithm, and provides an intuitive and unifying tool to analyze finite length LT codes. We first present the comprehensive description and theoretical identification of the proposed methodology, and then give some simulation results to validate its effectiveness.

Because of the rapid development of small satellite technology and the advantages of low earth orbit satellite (LEO) satellites compared with traditional geosynchronous orbit satellite (GEO) satellites such as low time delay low propagation loss broadband, LEO constellation satellite communication system has gradually become one of the hot spots in the field of satellite communication. At present, many countries and satellite communication companies in the world are working on broadband satellite communication system programmes. In view of the actual needs of our country, through link computation and comparing the complexity of satellite implementation at different communication elevation angles to meet the terminal rate requirements, the assumption of constructing broadband LEO constellation satellite communication system with high elevation is put forward. The transmission characteristics of OneWeb constellation are simulated by STK and Matlab simulation software.

This article investigates the capacity problem of an integrated remote wireless sensor and satellite network (IWSSN) in emergency scenarios. We formulate a general model to evaluate the remote sensor and satellite network capacity. Compared to most existing works for ground networks, the proposed model is time varying and space oriented. To capture the characteristics of a practical network, we sift through major capacity-impacting constraints and analyze the influence of these constraints. Specifically, we combine the geometric satellite orbit model and satellite tool kit (STK) engineering software to quantify the trends of the capacity constraints. Our objective in analyzing these trends is to provide insights and design guidelines for optimizing the integrated remote wireless sensor and satellite network schedules. Simulation results validate the theoretical analysis of capacity trends and show the optimization opportunities of the IWSSN.

Along with the development of the IPN (InterPlaNetary) Internet, the terrestrial Internet and interplanetary exploration network will be seamlessly merged with each other. However, significant challenges in control and management exist in such a complicated network. These include the efficient and reliable dissemination of control information, and the building up of an overlay network. This paper reviews current networking technologies for the IPN Internet and presents a novel architecture that divides it into subnets. A network model based on clusters is proposed to account for the problem of dynamic coupling among subnets and achieve monolithic controllability of the whole network. A new paradigm that separates the control and service planes is presented to reduce congestion and guarantee the reliable distribution of control information. We also present a modified version of a delay-tolerant-network protocol stack that separates the network layer into generalized inter-cluster sub-layers and discriminative intra-cluster sub-layers to improve the transmission efficiency of control information. Simulation results indicate that both the control and service data delivery is more efficient and reliable through clustering of the IPN Internet. Finally, we present recent achievements in network-information theoretical approaches that can be successfully applied to deep-space communication.

With the development of Spatial Information Network (SIN), the number of satellites in space continuously increases. However, the available spectrum resources are scarce. To address the spectrum scarcity, sharing the spectrum between different communication systems is a promising option. In this paper, a novel cognitive satellite scheme with geostationary earth orbit (GEO) and low earth orbit (LEO) broadband systems is studied. First, we present the concept of Cognitive Satellite Positioning (CSP) to describe the LEO satellite motion relative to the ground. Then, due to the uncertainty of space noises and absence of priori knowledge, an optimization algorithm with dual-threshold energy detection becomes a preferred candidate for satellite system, and a soft/hard fusion strategy is adopted so as to achieve a good balance between the traffic load of the dedicated links and the accuracy of Spectrum Sensing(SS). Finally, in conjunction with Radio Environment Mapping (REM) to improve the spatial reliability of SS. Numerical results show that the spectrum recognition scheme similar to the detection performance of cooperative SS only using soft fusion, which has strong robustness under environment with high uncertainty. The work here provides theoretical basis and technical support for the spectrum sharing strategy between GEO and LEO satellite system.