Efficient analysis of ultra-wideband wireless channels with three-dimensional ADI-FDTD algorithm

摘要

In this paper, an efficient three-dimensional (3-D) alternating direction implicit finite-difference time-domain (ADI-FDTD) algorithm has been used to analyze the electromagnetic characteristics of ultra-wideband wireless channel. Conventional FDTD has been successfully used for the electromagnetic analysis of wireless channel. However, there is one of the major limitations of FDTD, which is that the maximum time step is limited by the Courant-Friedrich-Levy (CFL) stability condition. A lot of time will be cost to calculate the electrical large model with the restricted time step, such as the wireless channel. A 3-D ADI-FDTD has been developed for its unconditional stability. In this algorithm, the time-step size is no longer limited by the CFL condition, while it is just restricted by the desired calculation accuracy. In this paper, ADI-FDTD has been used in the modeling of ultra-wideband wireless channel. The source excitation of ultra-wideband is described and the employed absorbing boundary condition is also given in this paper. Since ADI-FDTD is unconditionally stable, its time step size can be large and the time of computation can be saved. Typical ultra-wideband channel has been modeled by FDTD and ADI-FDTD. Accuracy of our ADI-FDTD has been proved by comparison with FDTD in this paper. The numerical examples of several indoor wireless channels are presented and analyzed. The time-domain waveforms of ADI-FDTD and FDTD are given to show that the time step size can be set ten times larger than conventional FDTD, the computational time of CPU can be saved 80 percent without the loss of accuracy. The efficiency of ADI-FDTD for the analysis of ultra-wideband wireless channel is be demonstrated.