Radio wave propagation modeling by combining ray-tracing with integral representations

无线电波传播模型在移动通信和雷达中变得越来越重要。移动通信向着具有大量天线的大规模MIMO等技术发展。雷达传感和成像在我们的日常生活中变得无处不在。特别是对于自主驾驶解决方案的实现，通过仿真在现实环境中生成准确的雷达数据是至关重要的，以避免在无休止的驾驶场景中收集雷达测量数据。射线追踪显然是在复杂环境中模拟无线电波传播的最有效的方法。然而，它仍然有一定的缺点，这使得它很难在微波和毫米波频率下使用。特别是在需要多次后续绕射的情况下，高频局部化的假定优势可能会成为一个严重的缺陷，因为多次(后续)绕射可能会导致巨大的计算时间，更糟糕的是，多次绕射计算的精度往往非常差。造成这种精度下降的主要原因是，仅计算边缘一点的绕射系数的局部化绕射计算不适合于现实环境的处理。申请人最近建立了一种结合互易定理的双向射线追踪方法，该方法已经可以克服传统单向光线追踪的一些缺点。这种方法的一个关键元素是包含积分表示，以克服传统的基于射线的传播模型的严格的局部化要求。这一战略应在拟议的项目中加以扩展，其中应根据惠更斯原则和等价原则，结合已经确立的互惠考虑，对复杂的传播情景进行划分。对单个分区进行光线跟踪处理，并根据相应的积分表示得到分区之间的相互作用。特别是对于雷达场景，该程序将允许将雷达目标本身的电磁模型和传播环境的电磁模型分离。将制定混合方法的公式，并将在图形处理单元(GPU)上实施、验证和优化强大的计算算法，其中将考虑各种复杂性的测试和验证场景。

Radio wave propagation modelling becomes increasingly important for mobile communications and radar. Mobile communications develops towards techniques such as massive MIMO with very large numbers of antennas. Radar sensing and imaging become ubiquitous in our daily lives. In particular towards the realization of autonomous drive solutions it is of paramount importance to generate accurate radar data in realistic environments by simulation, in order to avoid the collection of radar measurement data in endless drive scenarios. Ray-tracing is clearly the most powerful approach for radio wave propagation modelling in complex environments. However, it has still certain drawbacks, which make it difficult to use at microwave and millimeter wave frequencies. Especially in scenarios, which require several subsequent diffractions, the supposed advantage of high-frequency localization can become a severe drawback, since many (subsequent) diffractions can lead to an enormous amount of computation time and, even worse, the accuracy of multiple diffraction computations is often very bad. The major reason for this accuracy drop is that the localized diffraction computation by evaluating the diffraction coefficients for just one point on an edge is not suitable for the treatment of realistic environments. The applicant has recently established a bidirectional ray-tracing approach combined with the reciprocity theorem, which can already relieve some of the shortcomings of the conventional unidirectional ray-tracing. A key element of this approach is the inclusion of integral representations in order to overcome the stringent localization requirements of the traditional ray-based propagation modelling. This strategy shall be extended in the proposed project, where complex propagation scenarios shall be partitioned based on the Huygens’ and equivalence principles in combination with the already established reciprocity considerations. The individual partitions will be treated by ray-tracing and the interactions between the partitions are obtained based on the corresponding integral representations. In particular for radar scenarios, the procedure will allow to decouple the electromagnetic modelling of the radar targets itself and of the propagation environment. The formulations of the hybrid approach will be worked out and powerful computation algorithms on graphical processing units (GPUs) will be implemented, validated, and optimized, where test and validation scenarios of various complexities will be considered.