机间数据链中级联码OFDM系统的抗干扰研究

Anti-Jamming of Concatenated Coding OFDM System in Intra-Flight Data Link

为满足信息传输实时可靠、频谱使用高效灵活等技战术需求,在机间数据链(Intra-Flight Data Link,IFDL)物理层采用了多载波正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)传输体制。针对其抗干扰性能不足的问题,在突发干扰下对系统可靠性理论分析的同时,采用NASA提出的(255,223)Reed Solomon(RS)-(2,1,7)卷积"标准级联码",并与符号卷积交织相结合构成了前向纠错(Forward Error Correction,FEC)级联码方案。仿真结果表明,级联码OFDM系统在一定误码率下、不同IFDL信道环境中,均可获得较高编码增益,从而有效增强了机间数据链OFDM系统可靠性。此外,通过机载定向天线低截获传输,在保证隐蔽性的同时可进一步抑制多径衰落及跟踪干扰。

To meet the technical and tactical requirements of real-time and reliable data transmission, effective and flexible spectrum utilization, the multicarrier OFDM transmission scheme was adopted in the physical layer of Intra-Flight Data Link （IFDL）. Considering its problem of anti-jamming vulnerability, the OFDM system reliability in typical burst jamming was analyzed theoretically. Combined with convolution interleaving, （255,223） Reed Solomon-（2, 1,7 ） convolution concatenated code proposed originally by NASA, was applied in OFDM system to form Forward Error Correction （FEC） coding. The simulation results show that： 1 ） the concatenated coding OFDM system could achieve relatively large coding gains under certain Bit Error Rate（BER） in different IFDL channel environments, which can effectively enhance the reliability of OFDM system in IFDL; and 2） Low Probability of Intercept （LPI） transmission through the airborne directional antennas will further suppress the multipath fading and jamming while keeping stealth.