Spectrum Sensing for Weak Signals Based on Satellite Formation

Abstract

In this paper, we investigate the spectrum sensing of a weak signal based on multiple low earth orbit (LEO) satellites in the presence of a spectrum-sharing node, which can generate the interference imposed on the sensing LEO satellites. In order to improve the sensing ability of the weak signal, a cooperative spectrum sensing method relying on satellite formation is proposed. Specifically, firstly, some satellites will be chosen from multiple LEO satellites for formation purposes, where the specific number of satellites chosen can be adjusted by evaluating the probability of detection weak signal, as detailed later. Then, considering the object that both restraining the interference and magnifying the weak signal, the weighted value of each satellite for beamforming may be optimized with the aid of genetic algorithm, and the receive gains of the weak signal and the interference can be achieved. Finally, the probability of detecting the weak signal can be evaluated by calculating the signal to interference plus noise ratio (SINR), and the number of the chosen satellites can be decided accordingly. Simulation results show that the proposed method not only can suppress the interference imposed on the sensing satellites, but also can increase SINR of sensing satellites for the weak signal, resulting in improving the probability of detection.