为解决宽带航空数据链以内嵌方式工作在测距仪(DME)频道间而带来测距仪发射脉冲信号干扰宽带航空数据链正交频分复用(OFDM)接收机的问题,提出一种联合正交变换与信号交织的OFDM传输方法.首先,该方法利用测距仪脉冲信号在频域呈现为强相关高斯脉冲的特性,通过发射机正交变换与信号交织器,配合接收机解交织器与逆正交变换器将强相关脉冲转换为非相关脉冲;随后,基于期望最大化(EM)算法迭代重构非相关随机脉冲;最后,通过频率域脉冲干扰消除抑制脉冲干扰.仿真结果表明:所提出联合正交变换与信号交织的OFDM传输方法可有效抑制测距仪脉冲干扰,显著提高OFDM接收机链路传输的可靠性.
To mitigate the deleterious influence of distance measurement equipment (DME) interference on orthogonal frequency division multiplexing (OFDM) receiver of broadband aeronautical data link system operating as an inlay system,a new transmission method for OFDM system is proposed based on a joint orthogonal transform and signal interleaving.Firstly,utilizing the characteristic of DME pulse signal,i.e.,it exhibits a strongly correlated Gaussian pulse in the frequency domain,together with the orthogonal transformer and signal interleaver at the transmitter,we use the corresponding signal deinterleaver and inverse orthogonal transformer at the receiver to convert the correlated Gaussian pulse into uncorrelated random pulse.Secondly,the uncorrelated random pulse is reconstructed by expectation maximization (EM) iterative algorithm.Finally,the uncorrelated random pulse is eliminated in frequency domain.Simulation results show that the proposed transmission method for OFDM system based on a joint orthogonal transform and signal interleaving can suppress the correlated DME pulse interference effectively and significantly improve the reliability of the OFDM system.