Interference evaluations and simulations for multisatellite multibeam systems

Abstract

SUMMARYThird generation communication systems will be characterized by full integration between terrestrial and satellite components. To this aim, global coverage along with not severe requirements for user terminals are mandatory for the satellite segment and the use of constellations of satellites in low or medium Earth orbits (LEO or MEO) seems to be a viable solution. Those satellite systems will adopt multibeam antennas to achieve high spectral efficiency and low-cost terminals. Thus, interference becomes one of the most limiting factors in terms of both link availability and capacity.The paper presents a more complete interference model than previously published in literature. The identification of the interfering users set has been introduced and all the factors impacting interference generation or isolation have been considered in case of both FDMA and CDMA access. This model is suitable for instantaneous analysis of multisatellite constellations. It has been implemented and timedomain simulations have been performed to evaluate the impairments due to co-channel interference for different access techniques for LEO configuration.Simulation results on interference and users spatial distribution, on trade-offs between interference and system capacity will be presented. Finally, the main interference mitigation techniques will be listed and discussed.

Interference Modeling and Analysis for Inclined Projective Multiple Beams of GEO Satellite Communication Systems

“…6 In mobile satellite communication systems, on-board antenna acts as a spatial filter and the angular selectivity of beams is not very ideal, so the level of interference depends on the user angular separation, referred to the satellite position (see Fig. 4).…”

“…In recent years, interference analysis for multi-beam satellite systems has been widely researched, and different interference models for various application scenarios have been established. [6][7][8][9] Most are based on assuming beams as circles of the same size. However, due to great satellite coverage area, except the orthographic projection of the satellite, all other cells are approximate ellipses in actual systems.…”

“…Up Link Using the OFDM up-link C/I formula introduced by Ref. 6, the carrier power is the power transmitted by user (m,n); mn  is the angle between the tangent to the Earth in the location of user (m,n) and the line between the satellite and user (m,terminal antenna gain of user (m,n) in the direction of mn  ; n mn  is the angle between the boresight of cell n and the line between the satellite and user (m,is the satellite antenna gain in the cell n in the direction of n mn  ; mn d is the slant range for the link from user (m,n) to the satellite; NC is the number of cells reuse the same frequency as cell n; uc  is the activity factor of user (u,c), which depends on the service utilized by the user; n c  is the polarization isolation between cell c and cell n.Ref 6. introduces the most general up-link C/I formula, but it is not simplified for a specific scenario.…”

Multi-user interference pre-cancellation for downlink signals of multi-beam satellite system

“…In the downlink, signals can be preprocessed before transmitted by using multiple input multiple output (MIMO) precoding algorithms such as THP algorithm to cancel interference [5]. However, on-board antenna acts as a spatial filter in multi-beam satellite system, leading to a different interference scenario compared to that of terrestrial system [6]. If two users from adjacent beams are located very close to each other, their channel conditions are almost the same, so THP can no longer perform well.…”

Interference Modeling and Analysis for Inclined Projective Multiple Beams of GEO Satellite Communication Systems

“…In multi-beam satellite communication systems, on-board antenna acts as a spatial filter, leading to a different interference scenario compared to that of terrestrial systems. Interference analysis for multi-beam satellite systems has been widely researched recently, and different interference models for various application scenarios have been established [6][7][8]. Most are based on assuming beams as circles of the same size.…”