Patent ID: 8472961

Claim:
A portable terminal device which maintains wireless communication with a plurality of base stations in a communication network, comprising: a communication unit communicable in a plurality of frequency bands and configured to select one frequency band from the plurality of frequency bands to perform wireless communication; and a control unit configured to change the frequency band for use in the wireless communication by the communication unit to perform the wireless communication, wherein the control unit includes a first handoff processing unit which, when a neighboring base station list including information of one or more neighboring base stations is received from a currently communicating base station, measures a signal strength of a transmission signal for each of the one or more neighboring base stations in the frequency band being used by the communication unit, creates a first handoff candidate list in which one or more handoff candidates in a same frequency band are recorded in decreasing order of signal strength, and performs a handoff using the first handoff candidate list, and a second handoff processing unit which, when a second handoff candidate list including information for switching the communicating frequency band and one or more different frequency band handoff candidates is received from a currently communicating base station, measures signal strength of one or more base stations included in the second handoff candidate list, stops measuring signal strength of the one or more base stations included in the second handoff candidate list when a handoff condition is satisfied, reports the result of the signal strength measurement to the currently communicating base station, and performs a handoff based on a response to the report upon receipt of the response from the communication unit.