OFDM-Subcarrier Index Selection with Artificially Interfering Signals for Improving the Physical Layer Security of IoT-5G Systems

K. Ragini, K. Gunaseelan

Jehad M. Hamamreh

Nabil Romero‐Zurita, Mounir Ghogho, Des McLernon

Dimitrios E. Efstathiou

One benefit of 5G network deployment relates to the smaller size of cells allowing low latency and increased users capacity. The downside is that the potential eavesdroppers could be closer to the victim making the security more challenging. So it is clear the need for enhanced privacy protection in the next generation communications systems even for low power/low complexity IoT devices. The last few years there are numerous research efforts to enhance transmitted information security with complementary techniques that operate in physical layer. In this paper we propose a physical layer scheme that complements the security schemes implemented in the upper layers or/and in the physical layer. The proposed scheme takes advantage of the pilot subcarriers that are part of an OFDM transmission. Pilot subcarriers are essential for the pilot channel estimation process performed at the receiver. In conventional OFDM systems the positions of pilot subcarriers are known. In this paper we propose the positions of the subcarriers to change on every OFDM symbol following a probability distribution known only to the legitimate transmitter and legitimate receiver. This puts a passive eavesdropper at a relative disadvantage compared to a legitimate receiver, because it does not know the position of the pilot subcarriers. To evaluate the security performance of the proposed scheme the secrecy capacity and the outage probability are used as metrics.

Wenfei Liu, Ming Li, Guangyu Ti +2 more

This paper considers the problem of physical layer security of a wireless orthogonal frequency division multiplexing (OFDM) communication system. We first develop a transmit filter-aided secure OFDM system scheme which can disturb eavesdropper's receptions by destroying the orthogonality of OFDM signals at the eavesdropper, while the quality of legitimate transmission is maintained. Then, in an effort to further improve the security performance, we also propose an artificial noise (AN)-aided secure OFDM system associated with the transmit filter-aided approach. AN is generated in the null space of the legitimate channel by making use of residual power after power allocation for subcarriers. Therefore, AN can only disrupt eavesdropper's receptions but not affect legitimate receiver. Simulation results are presented to illustrate the efficiency of the proposed transmit filter and AN-aided physical layer security designs in the OFDM wiretap system.

Linhui Fan, Bo Tang, Qiuxi Jiang +2 more

The security issue on the physical layer is of significant challenge yet paramount importance for 5G communications. In some previous works, transmit power allocation has already been studied for orthogonal frequency division multiplexing (OFDM) secure communication with Gaussian channel inputs for both a single user and multiple users. Facing with peak transmission power constraints, we adopt discrete channel inputs (e.g., QPSK) in practical communication system, instead of Gaussian channel inputs. Discrete channel inputs impose a more significant challenge as compared with conventional Gaussian channel inputs for the multiuser wiretap OFDM system. This paper considers the joint resource allocation for time-domain artificial noise (AN) aided multiuser wiretap orthogonal frequency-division multiplexing (OFDM) channels with discrete channel inputs, providing secure 5G communications. This security problem is formulated as nonconvex sum secrecy rate optimization by jointly optimizing the subcarrier allocation, information-bearing power and AN-bearing power. To this end, with suboptimal subcarrier allocation scheme, we develop an efficient iterative algorithm to allocate the power between the signal and the AN via the Lagrange duality method. Finally, we carry out some numerical simulation to demonstrate the performance of the proposed algorithms.