A spectrum sharing model that counters eavesdropping

Abstract

Cybersecurity has become a major concern in the modern world. A serious threat to wireless networks is eavesdropping. On the other hand, usable spectrum is diminishing due to the presence of various wireless services. To address the problem, highly spectral efficient methods have been introduced e.g. spectrum sharing. Cognitive radio networks could sense unused spectrum and make use of it. In this paper, the cognitive radio is to perform a second task, i.e. jamming the eavesdropper. This paper is significant in revealing the cognitive radio’s energy efficiency in this setting, where a cognitive transmitter (CT) can transmit its own data when it senses the absence of primary transmitter (PT). If PT is present, CT is to jam an eavesdropper (EA) by transmitting artificial noise. Our main contribution is finding the CT’s optimal energy efficiency. Through the proposed formulas, we have determined the fractions of time and power required by CT to achieve the optimal energy efficiency, subject to constraints like minimum required secrecy rate Rs, etc. Our major findings are: (1) only a small portion of a time frame (66 μs in our setting) is required for sensing. CT can utilize the remaining time for sending its data or jamming EA. (2) To achieve a target energy efficiency of 0.5 bps/Hz/J, PT should not be actively transmitting more than 35% of the time, and Rs should not be larger than 1.2 bps/Hz.