HANDOFF METHOD BETWEEN DIFFERENT SYSTEMS AND WIRELESS TERMINAL

• US 20110256874A1
• Filed: 06/30/2011
• Published: 10/20/2011
• Est. Priority Date: 04/18/2007
• Status: Abandoned Application

• Current Assignee: Koichi Shiraishi, Masao Hayama
• Original Assignee: Koichi Shiraishi, Masao Hayama
• Inventors: Shiraishi, Koichi, HAYAMA, Masao
• Application Number:
  US13/172,913
• Publication Number:
  US 20110256874A1
• Time in Patent Office: Days
• US Class Current: 455/437
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

A method of performing a handoff between a plurality of wireless systems having different service areas and a wireless communication terminal are provided. A means for selecting one of the wireless systems to be connected according to the average moving speed of the wireless terminal is provided. When the average moving speed is changed across a certain threshold, the wireless terminal starts selecting one of the wireless systems as a handoff destination. Upon selection of the handoff destination, the current throughput is compared with the estimated throughput of the handoff destination. When an improvement in the throughput can be expected, the wireless terminal performs the handoff. The wireless terminal incorporates a plurality of control devices to select the handoff destination while communicating with the current wireless system.

Claims

1. 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.

2. A wireless terminal according to claim 1, wherein the wireless terminal comprises a memory device for storing through puts of up-link and down-link as statistics information measured periodically during communication and the controller determines whether the wireless terminal is used with the main down-link communication or with the main up-link communication based on the statistics information stored in the memory device and transmits a handoff determination request including a notified throughput of the determined main link based on the determination result.

3. A method of performing a handoff processing operation between a plurality of wireless communication systems performed by a wireless terminal in a situation where said wireless communication systems have different service areas and different throughputs respectively and are available;

the method has steps;

said wireless terminal compares the calculated moving speed of said wireless terminal and a threshold value,

selects one of the wireless communication systems having 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 including a notified throughput for the selected wireless communication system and receives a determined result of a communication quality in the 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,

executes a handoff to the selected wireless communication system when the notified throughput is expected.

4. A method of performing a handoff between a plurality of wireless communication systems according to claim 3, wherein the wireless terminal stores through puts of up-link and down-link statistics information measured periodically during communication, determines whether the wireless terminal is used with the main down-link communication or with the main up-link communication based on the statistics information and transmits a handoff determination request including a notified throughput of the determined main link based on the determination result.