MIMO cooperative spectrum sensing in hybrid satellite/terrestrial scenario

In a hybrid satellite/terrestrial scenario, the paper analyzes the advantages of using a cooperative scheme combined with Multiple-Input Multiple-Output (MIMO) technologies at each cognitive radio (CR) node for spectrum sensing. In the proposed scenario, the satellite and the terrestrial components use the same band (primary users) and a group of secondary users (sensors or mobile users) want to dynamically share the spectrum without harmful interference on primary user (PU). The satellite can also report measures provided by the group of secondary users to a remote center in an area where the mobile coverage it is difficult to extend or for emergency situations. The joint use of multiple antennas at each CR node and cooperative cognitive radio scheme is analyzed to improve the performance of the conventional energy detector (ED) and to increase the reliability in PU detection. A coordination center (CC) takes the final decision based on the detections carried out by all the CRS. Moreover, the CC can manage a strategy to allow equal and fare share of the radio resources to the group of CR nodes. The use of improved energy detector based on the average power of received samples is also analyzed. Simulation results show that the use of cooperation and MIMO technologies improves the detection even at low value of signal to noise ratio (SNR) and a trade off-it is necessary among the number of multiple antennas, the number of samples and the spectrum usage efficiency and the level of interference on the PU.