Comfort Noise Mechanism for Narrow Band Secure Voice Communication

In this paper, a new comfort noise method is proposed for a half-duplex narrowband secure voice communication system. A late network entry (LNE) mechanism for establishing and maintaining crypto synchronization requires periodically replacing voice frames with LNE frames. The comfort noise mechanism at the receiver generates voice frames to fill the gap resulting in dropped voice frames. The proposed comfort noise approach informs the receiver about the cross correlation between the frequency responses of dropped and neighboring frames for replacing the dropped frame with the most suitable one. The simulation results show that the proposed approach increases the voice quality under various channel conditions.