关键词: 隐蔽通信, Turbo 码, 并行译码, 尾比特

Abstract:

In covert communication with low signal-to-noise ratio, Turbo codes are used as channel coding to improve system reliability. A parallel decoding algorithm is proposed by inserting tail bits to reduce decoding delay and improve confidentiality. The periodical tail bits make the encoder return to a known status. In the decoder, the initial values of sub-blocks can be obtained from the zero-tail bits. The random tail bits can be viewed as pseudo information. Thus, confidentiality of the communication is enhanced. Simulation results show that, compared with conventional parallel decoding methods, the proposed scheme can improve Turbo decoding rate and reduce time delay without performance loss due to unknown boundary. The algorithm is suitable for high-speed communications in a low SNR environment.

Key words: tail bit, covert communication, Turbo codes, parallel decoding