Applications towards 6G have brought a huge interest towards arrays with a high number of antennas and operating within the millimeter and sub-THz bandwidths for joint communication and localization. With such large arrays, the plane wave approximation is often not accurate because the system may operate in the near-field propagation region (Fresnel region) where the electromagnetic field wavefront is spherical. In this case, the curvature of arrival (CoA) is a measure of the spherical wavefront that can be used to infer the source position using only a single large array. In this paper, we study a near-field tracking problem for inferring the state (i.e., the position and velocity) of a moving source with an ad-hoc observation model that accounts for the phase profile of a large receiving array. For this tracking problem, we derive the posterior Cram\'er-Rao Lower Bound (P-CRLB) and show the effects when the source moves inside and outside the Fresnel region. We provide insights on how the loss of positioning information outside Fresnel comes from an increase of the ranging error rather than from inaccuracies of angular estimation. Then, we investigate the performance of different Bayesian tracking algorithms in the presence of model mismatches and abrupt trajectory changes. Our results demonstrate the feasibility and high accuracy for most of the tracking approaches without the need of wideband signals and of any synchronization scheme. signals and of any synchronization scheme.
翻译:向 6G 应用后, 对使用大量天线的阵列产生了极大兴趣, 并且只能在毫米和亚THz带宽范围内运行, 以进行联合通信和定位。 有了如此大的阵列, 平流波近似往往不准确, 因为系统可能运行在电磁场波端具有球状的近地传播区域( 弗瑞斯内尔区域) 。 在此情况下, 抵达的曲解( 科阿) 是球形波面的测量标准, 可用于仅使用一个大阵列来推断源位置。 在本文中, 我们研究一个近地跟踪问题, 以推断一个移动源的状态( 即位置和速度), 因为这个系统可能运行于电磁场波波波波端的阶段性分布。 对于这个跟踪问题, 我们从远方阵列区域内部和外移动源位置时, 可以用来推断源值位置的精确度位置。 我们提供了一个近地跟踪问题信息在弗雷斯内尔区域之外定位信号的丢失情况, 的准确性模型的准确性是如何从我们方位轨迹轨迹的轨迹的轨迹的轨迹上, 的轨迹的, 而不是从我们所处的轨迹轨迹的轨迹的轨迹的轨迹的轨迹的轨迹的轨迹的轨迹上, 上, 的轨迹的轨迹的轨迹。