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.
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.
High level of security is essential in wireless 5G communications. The last few years there has been an increase in research interest in the potential of the radio channel’s physical properties to provide communications security. These research efforts investigate fading, interference, and path diversity to develop security techniques for implementation in 5G New Radio (NR). In this paper, we propose a collaborative scheme to existing physical layer security schemes, taking advantage of the characteristics of the OFDM technique. An OFDM symbol includes the pilot subcarriers, typically essential for the pilot channel estimation process performed at the legitimate receiver. In this work 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. An eavesdropper, does not have access to the information of the pilot subcarriers positions so, it performs blind channel estimation. The theoretical analysis is based on the information theoretic problem formulation and is confirmed by simulations. The performance metrics used are the secrecy capacity and the outage probability. The proposed scheme is very simple and robust, strengthening security in multimedia applications.
High level of security is essential in wireless communications multimedia applications. The last few years there has been an increase in research interest in the potential of the radio channel's physical properties to provide communications security. These research efforts investigate fading, interference, and path diversity to develop security techniques for implementation in wireless systems. In this paper, we propose an enhancement to existing physical layer security schemes, taking advantage of the characteristics of the OFDM technique. An OFDM symbol includes the pilot sub-carriers, essential for the pilot channel estimation process performed at the legitimate receiver. In this work we propose the positions of the sub-carriers to change on every OFDM symbol following a probability distribution known only to the legitimate transmitter and legitimate receiver. An eavesdropper receiver, does not have access to the information of the pilot sub-carriers positions so, it performs blind channel estimation. The theoretical analysis is based on the information theoretic problem formulation and is confirmed by simulations. The performance metrics used are the secrecy capacity, the outage probability, the channel mean square error and the bit error rate. The proposed scheme is very simple and robust, strengthening security in multimedia applications.
Open nature of wireless networks leads to being sensitive to eavesdropping. Hence, a tremendous growth of literature has carried out challenges in privacy and security in wireless networks. Conventional techniques would be highly susceptible to technological imperfections, over-exposed to eavesdroppers and dependent on complicated mathematics, leading to failure for deploying secure transmission wireless channels. In this study, we have significantly boosted the performance of the physical layer security in the 5G downlink transmission system by implementing the Orthogonal Frequency Division Multiplexing (OFDM) technique twice in the wiretap channel. We have fully compared the performance of exploiting the OFDM technique twice in the wiretap channel with its counterpart available approach with the one OFDM technique. This study has a major contribution to compare the performance of the two aforementioned techniques in terms of the secrecy capacity, the success rate of an eavesdropper, and the OFDM-modulation efficiency. The simulation results have verified that an extreme security rate and a very low success rate for the eavesdropper in the proposed technique. In addition, we have confirmed that the OFDM-64-QAM3/4 technique shows the ultimate performance in terms of a smaller number of errors, less value of BERs, and high rate modulation compared to the other modulation techniques. In the following, we have represented the simulation results of the active user throughput for the further evaluation of the proposed channel model.
The physical layer security of OFDM communication systems is getting more and more attention. Protecting the channel from eavesdroppers has received some attention. Artificial noise is generally considered to utilize the null space of the intended receiver's channel to interfere with the eavesdropper's channel, but it may not be able to defend against passive eavesdroppers. In this paper, a novel anti-eavesdropping OFDM system is proposed by using artificial pilot noise. Pilots play an important role in demodulating OFDM signal. In our proposed scheme, an auxiliary device called Helper would generate noise signals that overlap on the pilots sent by the user terminal. With the knowledge of the signals sent by the Helper, the receiver can decode the user terminal signal but eavesdroppers cannot. This would prevent eavesdroppers from overhearing the information transmitted between the user terminal and the receiver, so as to provide a secure communication for the user terminal. Finally, we use wireless open access research platform (WARP) v3 to test the feasibility and security of the scheme in practice. Our experimental results show that the proposed scheme can provide a secure communication in the environments with passive eavesdroppers.
In this paper, we investigate a physical layer security technique in an orthogonal frequency-division multiplexing (OFDM) based wireless communications. In an OFDM system, the legitimate transmitter (Alice) can increase secrecy capacity with proper power allocation and/or bit loading methods for example by maximizing mutual information for own communication, i.e. between Alice and the legitimate receiver (Bob). The reason of increasing secrecy capacity is that the power allocation is suitable for the channel state between Alice and Bob but not suitable for the channel state between Alice and the eavesdropper (Eve). In this paper, we investigate a new approach where dummy data is exploited to achieve further improvement of secrecy capacity. Specifically, real data and dummy data are implemented in transmit OFDM symbols and secure pilot signals are employed to inform the receiver about their respective locations. Two secure pilot signal designs are introduced and in both of them it is designed that Bob can easily detect correct real data locations but not for Eve. One of them uses fake pilot signals that cause Eve to mistakenly select dummy data as real data. Numerical results will show that secrecy capacity performance of the first secure pilot signal based secure communication (not using fake signal) is slightly less than the performance of water filling algorithm. One significant advantage of the first secure pilot signal based secure communication is that the computational cost should be significantly less than the water filling algorithm. In addition, we will show that fake pilot signal based secure communication can provide significant gain in secrecy capacity while the computational cost is still small.
In this work, novel physical layer security (PLS) schemes are proposed for orthogonal frequency-division multiplexing (OFDM) to secure both data and pilots in multiple-input multiple-output (MIMO) systems. The majority of previous studies focus on only securing the data without considering the security of the pilots used for channel estimation. However, the leakage of channel state information (CSI) from a legitimate node to an eavesdropper allows the latter to acquire knowledge about the channel of the legitimate nodes. To this end, we propose adaptive and flexible PLS algorithms which can 1) secure data, 2) secure pilots, and 3) jointly secure both data and pilots. Particularly, minimum-phase all-pass channel decomposition is exploited, where the proposed algorithms use the all-pass component to provide security without harming the performance of the legitimate user. In the analysis for data security, we evaluate the secrecy under correlated and uncorrelated eavesdropping channels via closed-form bit error rate (BER) formulas. For pilot security, we analyze the estimated channel’s normalized mean squared error (NMSE) performance. The simulation results and theoretical analysis demonstrate that the proposed algorithms can effectively enhance the communication secrecy of the overall system.