The present invention provides a mobile station apparatus. The mobile station apparatus comprises an RF transmitting/receiving module, a display module, a memory comprising an RSSI database, and a control program. When the mobile station apparatus moves along a path comprising plural candidates of communication locations, the control program records a plurality of RSSIs, which are received by the RF transmitting/receiving module from the candidates along the communication locations, and at least one path parameter in the RSSI database, and then according to a predetermined display algorithm, the control program controls the display module to display at least one recorded RSSI and the corresponding path parameter as a reference, based on which the mobile station apparatus selects a communication location candidate for providing the mobile communication service.