Analysis of LEO, MEO, and GEO global mobile satellite systems in the presence of interference and fading

Abstract

Several multisatellite and multispot systems have been recently proposed for provision of mobile and personal services with global coverage, adopting GEO or non-GEO (i.e., MEO, LEO) satellite constellations. The paper addresses an in-depth analysis of these constellations, evaluating both geometrical performance measures and cochannel interference levels caused by extensive frequency reuse. The geometrical analysis yields the statistics for coverage, frequency of satellite hand-overs, and link absence periods. The interference analysis is based on a general model valid for all access techniques, which is here applied to the case of FDMA. The outage probability as a function of the specification on carrier-to-interference power ratio is evaluated for four selected constellations. Several techniques are introduced for interference reduction in non-GEO systems, in which the satellites coverage areas may intersect: spot turnoff, intraorbital plane frequency division, and interorbital plane frequency division. The effects of Rice fading have also been analyzed by means of an analytic approximated method. The overall analysis allows a fair comparison between LEO, MEO, and GEO constellations

The Downlink Adjacent Interference for Low Earth Orbiting (LEO) Search and Rescue Satellites

“…In the case where the satellites are in close proximity within the main lobe of the receiving ground station antenna, long periods of interference between the two satellites can manifest itself. During these periods, the downlink of the adjacent satellites may be severely impaired [6]. Three pairs of operational SARSAT satellites are susceptible to this interference condition: S10/S12, S9/S11, and S7/S8 are identified and presented in Table 4 with their respective orbital periods and differences between them.…”

“…It is shown that the supplemental use of both reduces the time delay and increases coverage area. Only LEOs adjacent interference is discussed [6]. …”

“…This 'fly-over' is called a satellite pass. Communication reliability during a satellite pass may be degraded when satellites sharing the same downlink frequency are adjacent and interfere to each other, consequently degrading the received signal at the LUT [5,6].…”

Inline Interference Mitigation Techniques for Spectral Coexistence of GEO and NGEO Satellites

“…Furthermore, the contributions in [1,7,8,12,14] focus on hybrid coexistence scenario of satellite and terrestrial systems and the contributions in [6,9,11,13,15] address dual satellite coexistence scenarios. The interference scenario in a satellite system is different from that of the terrestrial systems due to the presence of the on-board antenna which acts as a spatial filter [2]. Cochannel interference mainly arises due to the presence of sidelobes in the on-board antenna radiation diagram i.e., non-ideal angular selectivity of the spotbeams.…”

“…GEO satellites utilize a circular orbit above the earth's equator maintaining the same position relative to the earth's surface whereas NGEO satellites generally have orbits with varying altitudes and positions. The main advantages of NGEO satellites are reduced free space attenuation, small propagation delay and the reduced cost of in-orbit injection per satellite [2]. Recently, the Others Three Billion (O3b) network has proposed to launch O3b satellites in the MEO of 8062 km in order to improve the round trip latency as compared to GEO orbit.…”