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The pilot spoofing attack is one kind of active eavesdropping activities conducted by a malicious user during the channel training phase. the finest secure beamformer that maximizes the achievable secrecy rate is found when both lawful and unlawful channel conditions are perfectly known. Artificial noise aided methods were proposed in this two-way training-based scheme. By transmitting the identical pilot (training) signals as those of the legal users, such an attack is able to manipulate the channel estimation outcome, which may result in a larger channel rate for the adversary but a smaller channel rate for the legitimate receiver. With the intention of detecting the pilot spoofing attack and minimizing its damages, we design a two-way training-based scheme. The effective detector exploits the invasive component created by the adversary, followed by a secure beamforming-assisted data communication. In addition to the solid discovery performance, this scheme is also capable of obtaining the estimations of both legitimate and illegitimate channels, which allows the users to achieve secure communication in the presence of pilot spoofing attack The achievable secrecy rate is utilized to measure the security level of the data transmission. In this proposed process without any pre-assumed knowledge of eavesdropper, the proposed scheme is still able to achieve the maximal secrecy rate in certain cases
Data transmission is the process of sending digital or analog data over a communication medium to one or more computing, network, communication or electronic devices.It enables the transfer and communication of devices in a point-to-point, point-to-multipoint and multipoint-to-multipoint environment.
Uplink channel estimations are available at the receiver, which allows it to make a test based on the difference between two estimation results.Pilot signals sent in the uplink channels.
Downlink channel estimations are available at the receiver, which allows it to make a test based on the difference between two estimation results.The detection outcome will be fed back to the transmitter together with the downlink channel estimation if needed.If the transmitter is equipped with multiple antennas to perform beamforming during downlink transmission.
It achieves much higher secrecy rate by using the detection and secure beamforming.The more accurate channel conditions we have, the larger secrecy rateTo be able to protect the confidential communication against the pilot spoofing attack.It identifies the spoofing attack path and replace the node of path which is affected through this secure transmission process
Classic cryptographic methods achieved secure communication by encrypting the confidential message as the unreadable cipher message, only the authentic receiver with valid secret key could decrypt and obtain the correct information However, another method dedicated to achieve secure transmission based on the physical layer property, named as physical layer security, has been proposed even before the cryptographic method Pioneering works by Wyner introduced the basic wiretap channel model which consists of a transmitter, a legal receiver and an eavesdropper (adversary), and defines the secrecy rate as the information rate that could be totally kept secret from the eavesdropper. This work has been extended by Csisz´ar and K¨orner to the general broadcast channel In recent decades, the development of multi-input-multioutput (MIMO) techniques (e.g., beamforming) provide a great opportunity to achieve a positive secrecy rate even when the legitimate channel is worse than the illegitimate one. In and the optimal secure beamformer that maximizes the achievable secrecy rate is found when both legitimate and illegitimate channel conditions are perfectly known.Due to that the CSI is essential for data transmission and reception, a pilot-assisted channel estimation method is widely used in practical systems
For example, in a time duplex division (TDD) system, the legal receiver is required to send the assigned pilot signals to the transmitter, and the CSI can be estimated based on the received pilot signals due to the reciprocity of the uplink and downlink channels. The pilot signal set is pre-designed and known by the transmitter and receiver, and different pilot signals are usually orthogonal to each other to avoid contamination phenomenon. Because of being repeatedly used and publicly known, the knowledge of pilot signals could easily be learned by an adversary, and the spoofing attack to the transmitter becomes possible by broadcasting the identical pilot signal as that of a legitimate receiver. By doing so, the adversary could manipulate the channel estimation result and benefit from the attack. If the transmitter is equipped with multiple antennas to perform beamforming during downlink transmission, e.g., maximum ratio transmission (MRT), the main beam of the data signal might be directed to the adversary or other unwanted destinations. This attack is named as pilot spoofing attack and obviously it could create terrible consequences. However, due to variable purposes of attacks, the pilot spoofing attack may not be the worst-case attack as the definition of worst-case could be subjective.Classic cryptographic methods achieved secure communication by encrypting the confidential message as the unreadable cipher message,Only the authentic receiver with valid secret key could decrypt and obtain the correct informationAnother method dedicated to achieve secure transmission based on the physical layer property, named as physical layer security, has been proposed even before the cryptographic method.
The main contributions of our work are summarized in four aspects: 1) Our proposed scheme needs no drastic modification to current transmission structure. For example, in the LTE-TDD system, the uplink pilot time slot (UpPTS) and downlink pilot time slot (DwPTS) is already implemented;2) The TWTD could achieve even higher detection probability than that of the ERD. Similar to the ERD, the threshold derived for the TWTD is also not dependent on the instantaneous channel conditions, which suggests such threshold, could be used among different time frames; 3) Unlike the ERD, our scheme is able to estimate both channels, switch to secure beamforming almost immediately and finally achieve positive secrecy rate within the same time frame;
4) Even without any prior information about Eve, our scheme is able to obtain the maximal secrecy rate in some cases, e.g., the adversary utilizes relatively large power. We introduce the system model utilized in this paper and related assumptions. Moreover, the negative impacts caused by pilot spoofing attack are also discussed. The detailed detection process of the two-way training detector is given, including the derivation of test threshold and evaluation of detection probability. Illustrates how to recover the secure transmission when the detection result indicates the existence of pilot spoofing attack. Contains the simulation set-up and results as well as the related discussions which verifies our theoretical
An active eavesdropping problem, i.e., Pilot spoofing attack. A two-way training based scheme has been proposed to defend such attack. The scheme first detects the attack by the unbalance of channel estimations at Alice and bob, and then formats the secure beamforming based on the estimations of legitimate and illegitimate channels. It is shown that the proposed scheme could achieve a high detection probability. Moreover, according to the two way channel estimation, the positive secrecy rate is proven to be achievable. With the further validation of numerical results, our two-way training based scheme has been proven to be able to protect the confidential communication against the pilot spoofing attack.