Search

This paper introduces the specific influence of adjacent satellite interference (ASI) as a unique negative propagation consideration affecting all types of satellite networks including global mobile satellite communication (GMSC) systems, which particularly negatively affects geostationary Earth orbit (GEO) satellite constellations. Any satellite network including GMSC could potentially cause ASI effects to their fixed and mobile users. There are two types of ASI effects, namely uplink and downlink ASI, which are discussed and examined in this paper. Downlink ASI occurs when the mobile receiving antenna beamwidth is large enough to receive additional signal levels from adjacent GEO satellites. On the other hand, uplink ASI occurs when adjacent satellites receive and rebroadcast strong uplink signals from mobile Earth station (MES) antennas, often because the antennas are either too small or improperly pointed. Modern mobile satellite terminals use very small antennas mounted onboard ships, land vehicles (road and rail), and aircrafts, including mobile military platforms. In practice, these mobile satellite communication terminals and antennas need to be small to increase transportability and facilitate easy installation. Antennas of this dimension greatly limit the achievable link budgets of satellite networks. In addition, the pointing error and focus of such antennas often requires using efficient modulation and power spectral density reduction technology successfully to mitigate all ASI influences. [ABSTRACT FROM AUTHOR]

This paper describes the effects of atmospheric attenuation and environmental influence as very important particulars for aeronautical Mobile Satellite Communications (MSC), because such factors generally tend to impair the performance of satellite links, although signal enhancements are also occasionally observed. As a radio frequency (RF) signal radiates through an Earth-to-sky communication link, its quality degrades as it propagates through the satellite link caused by the atmospheric attenuation, special propagation effects, environmental influence and many other interference considerations in space. This degradation significantly affects satellite transmission links, particularly the extent of degradation depends on the link, atmosphere, transmitted signal and receiver antenna parameters. The specific effects of clear sky, transionospheric propagation and path depolarization causes are examined and explained, focusing on important propagation characteristics in aeronautical MSC, reflection, fading, interference from adjacent satellite systems and specific local environmental influence caused by aircraft onboard superstructures. [ABSTRACT FROM AUTHOR]

This paper introduces modern projects and solutions of space systems for military and civilian Communication, Navigation and Surveillance (CNS) at sea, on the ground and in the air. Deploying new CNS technologies and techniques, military mobile assets, such as ships, land vehicles and aircrafts, including their personnel, will be connected, controlled and managed in more tactical, reliable and safe ways. The new satellite communication and navigation transponders onboard Geostationary Earth Orbit (GEO) satellites will able to provide connection and control of all military vehicles and personnel, enhance traffic control and management, improve safety and security of movements, and augment collision avoidance, especially for navy and air forces assets. The integrated CNS components for military applications described in this paper are solutions that provide reliable Mobile Satellite Communications (MSC), Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) and augmentation of Global Navigation Satellite Systems (GNSS). Separately, modern satellite CNS applications for the navy, ground and air forces with their technical concepts and advantages are discussed. [ABSTRACT FROM AUTHOR]