The present invention relates to a power saving in a wireless local area network including a plurality of access points providing at least one mobile station in each access point cell boundary with access service, the mobile station transits between an active mode and an idle mode. Thus, the panel is locked onto the housing by compressing the locking tenon and unlocked from the housing by pressing the press plate of the locking tenon so that the panel and housing assembly is assembled and disassembled easily and quickly without needing aid of any hand tool, thereby facilitating a user assembling and disassembling the panel and housing assembly. The state indicator receives an indication when the CPU is in a first state, which may be a busy state.