Effect of Non-Ideal Time Alignment on Cooperative Jamming Suppression in Physical Layer Security

In physical layer, cooperation jamming (CJ) can effectively enhance the transmission security of wireless communication. However, existing researches always assume that the CJ can be completely suppressed at the legal receiver, without considering the alignment impairment in practical systems. Considering nonideal time alignment, the residual CJ power at the legal receiver is analyzed. Then, a closed-form expression of jamming suppression ratio (JSR) is derived in terms of the normalized time alignment error and the received jamming-to-noise ratio (JNR), which evaluates the performance of CJ suppression at the legal receiver. Theoretical and simulation results confirm that non-ideal time alignment can significantly influence the JSR, and the system with lower CJ power is less sensitive to time alignment error.