Exclusion zone minimization and optimal operational mode selection for co-existent geostationary and non-geostationary satellites

Abstract

The number of satellites has been increasing in both geostationary (GEO) and non-geostationary (NGEO) earth orbits. Due to the limited availability of spectrum resources, the interference risk among these satellite networks has been increasing consequently. In such a scenario, the protection of existent GEO transmissions is crucial. In this paper, the co-existence downlink interference from a typical low earth orbit (LEO) constellation to earth stations of GEO satellites is examined for minimization of exclusion zone on the equatorial region. Two different operational scenario based on modulation and coding (MODCOD) with/without spread spectrum for the LEO system are considered. A multiobjective optimization problem (MOP) is formulated for nondominant solutions set based on exclusive angle minimization and bandwidth utilization of the LEO link. It is shown that the exclusive angle can be reduced up to 21.3% and 19.6%, compared with the initial anchor point at the transmission bit rates of 100 and 200 Mbps, respectively. The proposed optimal operational setting minimizes the interference risk to the GEO satellite network as well as maintains quality of service (QoS) for the LEO communication network. The results provide optimal operational mode selection for LEO satellite operators and/or decision makers.