减小信道编码安全间隙的两次加扰方案

安全间隙是衡量安全信道编码保密性能的重要参数,目前相关研究主要考虑误比特率(bit error rate, BER)安全间隙,未考虑误字率(word error rate, WER)安全间隙。为同时减小安全信道编码BER和WER安全间隙,提出一种两次加扰方案。在发送端信道编码器前后各设置一个加扰器,相应在接收端信道译码器前后各设置解扰器,同时增大低信噪比区域的接收BER和WER,减小BER和WER安全间隙。对方案的差错概率进行了理论分析,并对信道编码采用BCH码时系统的性能进行了仿真。理论和仿真结果表明,相较于采用相同信道编码和外扰码器的方案,所提方案在减小WER安全间隙的同时也减小了BER安全间隙。

Double scrambling scheme for reducing security gap of channel codes

The security gap is an important secrecy metric of security channel codes. Relevant works focous on the security gap of bit error rate (BER), rather than that of word error rate (WER). A double scrambling scheme is proposed to reduce the security gap of BER and WER simultaneously. Two scramblers are arranged respectively before and after the channel encoder at the transmitter, and two descramblers are arranged respectively before and after the channel decoder at the receiver. Both the BER and WER of the receiver are increased in the lower signal-noise ratio region. Therefore, the security gaps of BER and WER are decreased. The error rate is analyzed, and simulations are performed when BCH code is employed. Theory analysis and simulation results indicate that the proposed scheme is more effective in reducing the security gaps of BER and WER than the single scrambler scheme with the same channel code.