The broadcast nature of wireless communication makes it vulnerable to Eavesdropping. To enhance the communication security, cooperative jamming (CJ) is applied and studied in many previous works. However, jamming signal may also decrease the signal-to noise ratio (SNR) of legal receivers, and degrade the overall performance of networks. Therefore, the jammer power must be reasonably controlled. In this paper, the jamming power control over two-user Gaussian interference wiretap channel is investigated. We aim to establish the optimal scheme for each communication pair with game theory. To maximize secrecy rate with minimal jamming power, we first derive the pure and mixed strategies Nash Equilibrium (NE) in non-cooperative game frame. Then given the overall utility and fairness, we establish a cooperative game. In cooperative game frame, time-sharing mechanism is used. In both frames, we derive best equilibrium strategy for each transmitter. Numerical results demonstrate that the system utility is really improved with jamming power control based on game theory.
The broadcast nature of wireless communication makes it vulnerable to Eavesdropping. To enhance the communication security, cooperative jamming (CJ) is applied and studied in many previous works. However, jamming signal may also decrease the signal-to noise ratio (SNR) of legal receivers, and degrade the overall performance of networks. Therefore, the jammer power must be reasonably controlled. In this paper, the jamming power control over two-user Gaussian interference wiretap channel is investigated. We aim to establish the optimal scheme for each communication pair with game theory. To maximize secrecy rate with minimal jamming power, we first derive the pure and mixed strategies Nash Equilibrium (NE) in non-cooperative game frame. Then given the overall utility and fairness, we establish a cooperative game. In cooperative game frame, time-sharing mechanism is used. In both frames, we derive best equilibrium strategy for each transmitter. Numerical results demonstrate that the system utility is really improved with jamming power control based on game theory.
With the emergence of physical layer security, there has been an increasing interest toward its framework comprising a wiretap channel with a transmitter, a receiver, and an eavesdropper. In this paper, the eavesdropper operates in a full-duplex mode so as to reduce the secrecy rate of the transmitter-receiver pair through simultaneous wiretapping and jamming. On the other hand, the transmitter-receiver pair aims to increase its achievable secrecy rate. To examine the power decision processes between the transmitter and the eavesdropper, a two-player noncooperative game is proposed. We first provide sufficient conditions for the existence of the pure-strategy Nash equilibrium (NE), and then derive the closed-form NEs for two special cases, i.e., the eavesdropper close to and far away from the receiver. For discrete approximation of the game, we utilize a fictitious play-based algorithm to achieve the mixed-strategy NE. Based on the equilibrium, a switch policy is provided for the eavesdropper to determine its optimal mode between the full-duplex and half-duplex, depending on the self-interference and location. Numerical results show that this switch policy improves the monitoring performance in terms of utility, which is the linear combination of the secrecy rate and the power consumption.
Cooperative jamming approach has been commonly used in the field of physical layer security to achieve a good secrecy rate of wireless networks. In this approach, the Gaussian noise signal sent by a friendly jammer can disrupt the reception of the eavesdropper, however, it may also interfere with the legitimate receiver. In this paper, we propose a novel approach, namely, information jamming, to go beyond the secrecy rate achieved by the traditional cooperative jamming approach in a multiple-input single-output (MISO) wiretap channel. We propose that a multi-antenna friendly jammer transmits the source message rather than Gaussian noise signal for simultaneously enhancing the signal strength at the legitimate receiver and canceling the received signal at the eavesdropper. In particular, we aim to maximize the achievable secrecy rate by optimizing the information jammer's beamforming vector. Though the optimization problem is non-convex, we successfully solve it optimally via a two-stage based numerical approach. To gain more useful analytical results, we also propose two suboptimal jamming schemes with low computation, by targeting at improving the legitimate reception and avoiding the eavesdropping, respectively. Finally, numerical results show that the proposed information jamming approach significantly helps go beyond the secrecy rate of the existing cooperative jamming approach, especially when the transmit power of the jammer is large enough.
This paper considers a Gaussian multi-input multi-output (MIMO) wiretap channel with a legitimate transmitter, a legitimate receiver (Bob), an eavesdropper (Eve), and a cooperative jammer. All nodes may be equipped with multiple antennas. Traditionally, the jammer transmits Gaussian noise (GN) to enhance the security. However, using this approach, the jamming signal interferes not only with Eve but also with Bob. In this paper, besides the GN strategy, we assume that the jammer can also choose to use the encoded jammer (EJ) strategy, i.e., instead of GN, it transmits a codeword from an appropriate codebook. In certain conditions, the EJ scheme enables Bob to decode the jamming codeword and thus cancel the interference, while Eve remains unable to do so even if it knows all the codebooks. We first derive an inner bound on the system’s secrecy rate under the strong secrecy metric, and then consider the maximization this bound through precoder design in a computationally efficient manner. In the single-input multi-output (SIMO) case, we prove that although non-convex, the power control problems can be optimally solved for both GN and EJ schemes. In the MIMO case, we propose to solve the problems using the matrix simultaneous diagonalization (SD) technique, which requires quite a low computational complexity. Simulation results show that by introducing a cooperative jammer with coding capability, and allowing it to switch between the GN and EJ schemes, a dramatic increase in the secrecy rate can be achieved. In addition, the proposed algorithms can significantly outperform the current state of the art benchmarks in terms of both secrecy rate and computation time.
Optimal cooperative jamming (CJ) is studied for multiuser multiple-input multiple-output (MU-MIMO) broadcast channel to enhance the physical layer security with the help of a friendly jammer (FJ). We first derive a necessary and sufficient condition to achieve the asymptotically perfect security and propose an optimal CJ scheme to minimize the maximum signal-to-interference-plus-noise ratio (SINR) at the eavesdropper subject to a power constraint at the FJ. Then we derive an achievable lower bound of the eavesdropper's SINR and propose an asymptotically optimal CJ scheme achieving the lower bound. Numerical results demonstrate that the proposed schemes are effective.
We investigate optimal power allocation strategies over a OFDM Gaussian wiretap channels where a legitimate transmitter and a legitimate receiver communicate in the presence of an eavesdropper and a jammer-who acts as unfriendly to both the legitimate parties and the eavesdropper. In particular, we formulate a zero-sum power allocation game between the transmitter and the jammer where the payoff function is the secrecy rate. We characterize the optimal power allocation strategies as well as the Nash equilibrium in some asymptotic regimes. We also provide a set of results that cast further insight into the problem.
This paper considers cooperative jamming (CJ) to ensure secure communication between the transmitter and the legitimate receiver. CJ serves as an effective and promising way to confuse the eavesdropper. However, in the presence of the CJ, the secrecy capacity is obtained at a certain cost of power, which consists of two parts: one part is the extra power consumed by transmitting CJ, and the other part is the signal-to-noise ratio (SNR) loss caused by imperfect CJ cancellation at the authorized receiver, which can be equivalent to the wasted power of the desired signal. In this paper, we both take into account the imperfect CJ cancellation and the extra power penalty to analyze the secrecy capacity, which can be a measurement of system security performance. Numerical simulation is adopted, revealing that the proposed scheme reduces the proportion of power used to transmit jamming signals, and achieves almost the same secrecy capacity as the case which does not take the extra power penalty into consideration. Moreover, the channel capacity of the desired signal is improved.