Design of Universal Wireless Channel Generator Accounting for the 3-D Scatter Distribution and Hardware Output

Hardware to generate the wireless channel is indispensable to the tests of wireless equipment. Previous literature always focused on the pure-hardware design, which is difficult or expensive for the small- and medium-sized enterprises. Hence, this paper presents a simple strategy to develop a flexible and low-cost channel generator, where the theoretical derivation and hardware realization are integrated together to save the test-cost and reduce the realization difficulty. In the proposed method, the fading channel is first modeled in the Agilent advanced design systems (ADS) software, and then a conventional signal generator hardware is connected and controlled to output the physical fading signal to wireless equipment waiting for measurements. Meanwhile, to cover a widerange of fading scenarios, we exploit 3-D geometry-based stochastic channel model as well as the autoregressive (AR) modeling technique. In general, for a given nonisotropic 3-D scattering environment, the angle of arrival, autocorrelation function, and level crossing rate are derived first, and then the AR coefficients are obtained by solving the Yule-Walker equation. Finally, the AR coefficients are fed to the ADS software to control the hardware generating channels. In addition, the channel model and the radio frequency parameters can be controlled by the ADS software, yielding a great flexibility. We verify the proposed method via both the computer simulation and the hardware measurement, and the simulation agrees with the theoretical result well. In addition, the physical measurements also demonstrate that the physical fading channels are consistent with the design specifications.