Handoff method between different systems and wireless terminal

A wireless terminal comprising:

• a plurality of communication processors compatible with wireless communication systems having different service areas and different throughputs respectively;
• at least two antennas;
• at least two wireless communication units for transmitting and receiving an electric wave in a communication system of any of said communication processors via the antennas;
• a controller for controlling constituent elements of said wireless terminal;
• and
• a terminal state detector,
• wherein, said terminal state detector calculates a moving speed of said wireless terminal,
• said controller compares the calculated moving speed of said wireless terminal and a threshold value,
• selects associated one of wireless communication systems of a rank corresponding to the comparison result of the calculated moving speed of said wireless terminal and the threshold value from said wireless communication systems which are previously ranked according to sizes of the service areas and to an average throughput,
• judges whether the selected wireless communication system exists in an area where said wireless terminal exists,
• when said wireless communication system exists, transmits a handoff determination request for the selected wireless communication system including a notified throughput, receives a result of determination of a communication quality in the selected wireless communication system,
• when the notified throughput is not expected, said wireless terminal selects a wireless communication system of lower ranks than a current rank in sequence, and,
• when the notified throughput is expected, said wireless terminal executes a handoff to said selected wireless communication system.