如果max_number_of_sdcchs=24 number_of_sdcchs_preferred=16 sdcch_need_low_water_mark=16 sdcch_need_high_water_mark=4 那么在第一次由TCH向SDCCH再配置時(shí),有多少個(gè)SDCCH已經(jīng)被占用?()