Secure resource allocation in OFDMA-based cognitive radio networks with two-way relays

In this paper, we consider a two-way cooperative communication framework to provide secure communications for secondary users within an Orthogonal Frequency-Division Multiple Access (OFDMA) based underlay cognitive network. By proposing a radio resource allocation problem with the aim of maximizing the secrecy sum-rate of secondary users and solving it, we show that deployment of relays is vital to achieve a non-zero secrecy sum rate. Also, impact of two-way relay in system performance improvement is clearly visible in comparison with one-way relay such that it can roughly double the resulting system secrecy sum-rate. The impact of different system parameters on the achievable secrecy sum rate for both one-way and two-way relay is also investigated and compared through simulations.