COMMUNICATION TERMINAL OUT-OF-RANGE DETERMINING METHOD, WIRELESS COMMUNICATION SYSTEM SWITCHING METHOD AND COMMUNICATION TERMINAL, PARTICULARLY FOR ACCURATELY DETERMINING WHETHER A COMMUNICATION TERMINAL IS OUT OF RANGE EVEN WHEN UPSTREAM AND DOWNSTREAM COMMUNICATION METHODS ARE DIFFERENT

摘要

PURPOSE: A communication terminal out-of-range determining method, a wireless communication system switching method and a communication terminal are provided to initiate preparation of switching a current communication method to a different communication method based on an upstream transmission signal level. CONSTITUTION: A communication terminal and a base station communicate with each other(S1). The communication terminal receives an instruction related to a transmission level of a transmitted signal from the base station(S2). A determining unit of the communication terminal determines whether the transmission level is equal to or greater than a maximum value or a certain threshold value(S3). If the transmission level is equal to or greater than the maximum value or the certain threshold value, the communication terminal receives more instruction for raising the transmission level of the transmission signal from the base station(S4). The determining unit of the communication terminal determines that an uplink signal from the communication terminal to the base station does not reach the base station and judges that the communication terminal is out of range(S5).