Abstract
In this paper, we consider a space-time line coded (STLC) system having two-transmit and two-receive antennas. To improve the secrecy rate of the STLC system, in which an illegitimate receiver eavesdrops the information delivered from the STLC transmitter to the STLC receiver, we propose an artificial noise (AN) injection method. By exploiting the STLC structure, a novel AN for the STLC is designed and its optimal power loading factor is derived. Numerical results verify that the proposed secure STLC systems with the designed AN injection and the power control method can significantly improve the secrecy rate compared to the conventional STLC systems. It is observed that the proposed method is more effective if there is a significant gap between the main-channel and the eavesdropper-channel gains.
Highlights
For secure wireless communications, along with cryptographic encryption on an application layer, physical-layer security (PLS) technologies [1,2,3] have been attracting intensive research interest from various fields with numerous successful applications, such as wireless power transmission systems [4,5], massive multi-input multi-output (MIMO) systems [6,7], millimeter wave systems [8], and unmanned aerial vehicle systems [9,10,11,12]
By adding artificial noise (AN) to the transmitted signals at a transmitter (i.e., Alice), the secrecy capacity can be significantly improved as the AN affects as an interference only on an eavesdropper (i.e., Eve), not a legitimate user (i.e., Bob)
From Equation (12), we verify that the secure space-time line code (STLC) achieves performance identical to that of the conventional STLC and space-time block coded (STBC) in terms of the spatial diversity gain
Summary
Along with cryptographic encryption on an application layer, physical-layer security (PLS) technologies [1,2,3] have been attracting intensive research interest from various fields with numerous successful applications, such as wireless power transmission systems [4,5], massive multi-input multi-output (MIMO) systems [6,7], millimeter wave systems [8], and unmanned aerial vehicle systems [9,10,11,12]. Contrary to an anti-jamming scheme that intends to remove the jamming signals from the received signals [13,14], i.e., the data protection from the jammer’s attack, the PLS technologies are mainly focused on the data protection from being eavesdropped by the eavesdropper. Various practical PLS techniques, such as the precoding/beamforming schemes [15,16], the cooperation methods [17,18,19,20], the secrecy-achieving codes [21,22,23], and artificial noise (AN). Injection [24,25,26,27,28,29], have been studied. The AN injection methods have been vigorously studied due to their simplicity and effectiveness. In [27,28], an AN was designed for a secure space-time block coded (STBC) system to improve the secrecy rate of the STBC systems
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