Anti-eavesdropping FrFT-OFDM system exploiting multipath channel characteristics
Anti-eavesdropping FrFT-OFDM system exploiting multipath channel characteristics
复制标题
利用多径信道特性的防窃听FrFT-OFDM系统
DOI：
10.1049/iet-com.2016.1251
复制
发表时间：
2017
影响因子：
1.6
通讯作者：
Wang Yue
中科院分区：
文献类型：
--
作者：
Wang Teng;Huan Hao;Tao Ran;Wang Yue
本研究利用无线信道响应与分数傅立叶变换（FrFT），在多径信道下实现抗窃听的下行传输。该系统工作在时分双工模式下，只有发送端通过上行业务知道主信道响应。利用主信道信息，提出了一种时变扩频正交频分复用（TS-OFDM）子系统实现保密变换阶数（TO）传输，并提出了一种安全增强的FrFT-OFDM（SE-FrFT-OFDM）子系统实现高速数据传输。还提供了优化TS-OFDM子系统的平均保密中断容量和SE-FrFT-OFDM子系统的误比特率性能的最优功率分配算法。在信道互易性和空间去相关的情况下，合法用户可以获得最佳的抗多径衰落性能，但截获的数据符号将同时受到信道衰落和TO偏差的随机化。为了避免随机化，窃听者必须测试多个SE-FrFT-OFDM符号的所有可能的TO组合，这通常是不切实际的任务。与其他典型方法相比，所提出的系统的发射功率可以被更有效地使用，因为数据符号不与附加干扰一起沿着发射。计算机仿真验证了该方案的有效性。
This study exploits wireless channel response and fractional Fourier transform (FrFT) to achieve anti-eavesdropping downlink transmission over a multipath channel. The proposed system works in time-division duplexing mode, and only the transmitter knows the main channel response through uplink services. With the use of the main channel information, a time-varying spread-spectrum orthogonal frequency division multiplexing (TS-OFDM) subsystem is proposed to realise confidential transform order (TO) transmission, and a security-enhanced FrFT-OFDM (SE-FrFT-OFDM) subsystem is presented for high-rate data transmission. The optimal power allocation algorithms that optimise the average secrecy outage capacity of the TS-OFDM subsystem and the bit error rate performance of the SE-FrFT-OFDM subsystem are also provided. Given channel reciprocity and spatial decorrelation, the legitimate user can achieve optimal anti-multipath fading performance, but the intercepted data symbols will be randomised by both channel fading and TO deviations. To avoid randomisation, the eavesdropper has to test all possible TO combinations of multiple SE-FrFT-OFDM symbols, which is usually an impractical task. Compared to other typical methods, the transmitting power of the proposed system can be used more efficiently because the data symbol is not transmitted along with additional interference. Computer simulations are carried out to validate this scheme.