To extract arsenic from intermediates containing arsenic, to outside the system in stable form. The addition of zirconium tungstate powders as the seeds in the process can effectively reduce the steps, shorten the preparation time, lower the sintering temperature and duration, save the cost, and provide the zirconium tungstate ceramic body with uniform microstructure. An external surface and a periphery rotates along the central axis; a color filter plate shares a same central axis with the carrier, wherein an annular groove is disposed on the external surface of the carrier. The method includes, during the restricted access window, accessing the wireless medium using first channel access parameters; and after the restricted access window but before the second beacon, accessing the wireless medium using second channel access parameters.