Impact of multibeam antenna design on interference for LEO constellations

The severe constraints characterising satellite communications and the need to reduce the user terminal requirements impose restrictions on obtaining high on-board performance. If satellite systems aim at providing a large set of multimedia services to a large set of users, as standalone systems or as a real complement to terrestrial networks, considering the scarce bandwidth allocation, pursuing the improvement of payload characteristics we can get the target performance. To reach this goal the use of multibeam antennas for coverage patterns as similar as possible to terrestrial cellular systems is practically mandatory. The increased number of beams allows greater spatial selectivity helping in alleviating interference constraints and in implementing fading countermeasure techniques. The increase of the number of beams has to be traded off among the co-channel interference, complexity, costs and the maximisation of the spectral efficiency. In this paper the problem of interference in multibeam satellite systems is described and the impact of antenna design on interference is quantified for a LEO constellation. The results of simulations carried out using a simulator capable of performing dynamic analysis varying the number of beams are presented