Abdelgawwad Ahmed, Borhani Alireza, Pätzold Matthias
Faculty of Engineering and Science, University of Agder, P.O. Box 509, 4898 Grimstad, Norway.
Sensors (Basel). 2020 Feb 14;20(4):1049. doi: 10.3390/s20041049.
This paper is about designing a 3D no n-stationary wideband indoor channel model for radio-frequency sensing. The proposed channel model allows for simulating the time-variant (TV) characteristics of the received signal of indoor channel in the presence of a moving object. The moving object is modelled by a point scatterer which travels along a trajectory. The trajectory is described by the object's TV speed, TV horizontal angle of motion, and TV vertical angle of motion. An expression of the TV Doppler frequency caused by the moving scatterer is derived. Furthermore, an expression of the TV complex channel transfer function (CTF) of the received signal is provided, which accounts for the influence of a moving object and fixed objects, such as walls, ceiling, and furniture. An approximate analytical solution of the spectrogram of the CTF is derived. The proposed channel model is confirmed by measurements obtained from a pendulum experiment. In the pendulum experiment, the trajectory of the pendulum has been measured by using an inertial-measurement unit (IMU) and simultaneously collecting CSI data. For validation, we have compared the spectrogram of the proposed channel model fed with IMU data with the spectrogram characteristics of the measured CSI data. The proposed channel model paves the way towards designing simulation-based activity recognition systems.
本文旨在设计一种用于射频传感的三维非平稳宽带室内信道模型。所提出的信道模型能够模拟在存在移动物体的情况下室内信道接收信号的时变特性。移动物体由沿轨迹移动的点散射体建模。该轨迹由物体的时变速度、时变水平运动角度和时变垂直运动角度描述。推导了由移动散射体引起的时变多普勒频率的表达式。此外，还给出了接收信号的时变复信道传递函数（CTF）的表达式，该表达式考虑了移动物体和固定物体（如墙壁、天花板和家具）的影响。推导了CTF频谱图的近似解析解。通过摆实验获得的测量结果验证了所提出的信道模型。在摆实验中，使用惯性测量单元（IMU）测量了摆的轨迹，并同时收集了CSI数据。为了进行验证，我们将输入IMU数据的所提出信道模型的频谱图与测量的CSI数据的频谱图特征进行了比较。所提出的信道模型为基于仿真的活动识别系统的设计铺平了道路。
