Artificial-Noise Aided Secure Transmission in Large Scale Spectrum Sharing Networks

• Published in: IEEE transactions on communications Vol. 64; no. 5; pp. 2116 - 2129
• Main Authors: Yansha Deng, Lifeng Wang, Zaidi, Syed Ali Raza, Jinhong Yuan, Elkashlan, Maged
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Artificial noise; Physical layer; physical layer security; Quality of service; Radio transmitters; Receivers; Resource management; Security; spectrum sharing networks; power allocation; physical layer security; spectrum sharing networks; stochastic geometry; Artificial noise
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2016.2544300

We investigate beamforming and artificial noise generation at the secondary transmitters to establish secure transmission in large scale spectrum sharing networks, where multiple noncolluding eavesdroppers attempt to intercept the secondary transmission. We develop a comprehensive analytical framework to accurately assess the secrecy performance under the primary users' quality of service constraint. Our aim is to characterize the impact of beamforming and artificial noise generation (BF&AN) on this complex large scale network. We first derive exact expressions for the average secrecy rate and the secrecy outage probability. We then derive an easy-to-evaluate asymptotic average secrecy rate and asymptotic secrecy outage probability when the number of antennas at the secondary transmitter goes to infinity. Our results show that the equal power allocation between the useful signal and artificial noise is not always the best strategy to achieve maximum average secrecy rate in large scale spectrum sharing networks. Another interesting observation is that the advantage of BF&AN over BF on the average secrecy rate is lost when the aggregate interference from the primary and secondary transmitters is strong, such that it overtakes the effect of the generated AN.