A Radio Environment Mapping Based Spectrum Awareness for Cognitive Space Information Network with GEO and LEO Coexistence

Abstract

Cognitive radio provides a promising solution for contradiction between increasing service requirements and spectrum resource scarcity in space information network. A novel algorithm of space-borne spectrum awareness based on radio environment mapping (REM) with a hybrid dual-threshold approach of spectrum sensing (SS) is proposed for coexistence of geostationary earth orbit (GEO) incumbent down-links and low earth orbit (LEO) cognitive up-links in this paper. The constructed hybrid SS approach integrates single-node energy detector and equal-gain combining, and provides a good trade-off between the design complexity and the SS accuracy of a LEO cognitive system in an environment with highly uncertain noise. In addition, the concept of cognitive satellite position (CSP) is proposed to deal with negative effect of sparsely distributed LEO cognitive nodes and to enable space-borne hybrid SS and REM according to rapid movement of the LEO cognitive nodes. Spatial detection probability and spatial false alarm probability are drawn into the work to indicate spatial reliability of our space-based REM. The numerical results show that the created hybrid dual-threshold SS approach is robust to highly uncertain noise environment, and that the dynamic REM approach based on the SS results at LEO CSPs could provide spectrum awareness at the considered scenario with high spatial reliability. Furthermore, a simulated instance of space-borne REM application under GEO and LEO coexistence is afforded and an instructive observation from this instance is discussed. The work here offers fundamental support for spectrum sharing of space information network.