Wireless Communication Terminal and Method of Controlling the Same

• US 20100142477A1
• Filed: 11/28/2007
• Published: 06/10/2010
• Est. Priority Date: 11/29/2006
• Status: Active Grant

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Yokota, Tomoyoshi
• Granted Patent: US 8,626,171 B2
• Time in Patent Office: Days
• US Class Current: 370/331
• CPC Class Codes: H04W 36/0072 of resource information of target access point
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data

Abstract

It is judged whether a mobile node 11 exists at a boundary A overlapped with a different sector of the base station for use in communication or at a boundary B overlapped with an area of another base station or at an area fringe C. In accordance with the application in use and the results thus judged, a handover is performed between base stations in a wireless communication system, or switching to the another wireless communication system is made, or simultaneous communication with the another wireless communication system is performed, or either the uplink or the downlink is switched to the another wireless communication system.

Claims

1. A wireless communication terminal, which performs communication by one wireless communication system using a broadband and wide-area network where a base station broadcasts allocation information of downlink burst to a terminal belonging thereto by using an application having real time characteristic, comprises:

a communication unit for performing communication with another wireless communication system using a wide-area network, to which network seamless handover between base stations or sectors of a base station is carried out;

a judging unit for judging, when the wireless communication terminal is performing communication by the one communication system, whether the wireless communication terminal exists at a boundary overlapped with a different sector of the base station for use in communication or at a boundary overlapped with an area of another base station or at an area fringe of the base station for use in communication not overlapped with a sector of the base station for use in communication or an area of another base station; and

a control unit for controlling, according to the application in use and the results made by the judging unit, such that a handover is performed between base stations in the one wireless communication system, or switching to the another wireless communication system is made, or simultaneous communication with the another wireless communication system is performed in order to complement the communication with the one wireless communication system, or either the uplink or the downlink is switched to the another wireless communication system.

2. The wireless communication terminal of claim 1, further comprising a detection unit for detecting a received signal strength indicator and a signal-to-noise ratio,

wherein the judging unit judges, when the received signal strength indicator and the signal-to-noise ratio satisfy predetermined conditions for a predetermined period, that the wireless communication terminal exists at an area fringe of the base station for use in communication not overlapped with a sector of the base station for use in communication or an area of another base station.

3. The wireless communication terminal of claim 2, wherein, when the judging unit judges that the wireless communication terminal exists at an area fringe of the base station for use in communication not overlapped with a sector of the base station for use in communication or an area of another base station of the same wireless network, the control units performs control such that either the uplink or the downlink is switched to the another wireless communication system.

4. The wireless communication terminal of claim 2, further comprising a detection unit for detecting communication quality and received signal strength indicator of the wireless communication terminal,

wherein the judging unit judges, when the communication quality and the received signal strength indicator satisfy a first condition, that the wireless communication terminal exists at a boundary overlapped with a different sector of the base station for use in communication.

5. The wireless communication terminal of claim 4, wherein, when the judging unit judges that the wireless communication terminal exists at a boundary overlapped with a different sector of the base station for use in communication, the control units performs control such that switching to the another wireless communication system is made.

6. The wireless communication terminal of claim 4, wherein, when the communication quality and the received signal strength indicator satisfy a second condition in which the received signal strength indicator is set lower than that in the first condition, the judging unit judges that the wireless communication terminal exists at a boundary overlapped with an area of another base station.

7. The wireless communication terminal of claim 6, wherein, when the judging unit judges that the wireless communication terminal exists at a boundary overlapped with an area of another base station and the application having real time characteristic is a streaming application, the control units performs control such that a handover is performed between base stations in the wireless communication system.

8. The wireless communication terminal of claim 6, wherein, in a case where the application having real time characteristic is a VoIP application and the judging units judges that the wireless communication terminal exists at a boundary overlapped with an area of another base station, the control units performs control such that either switching to the another wireless communication system is made or simultaneous communication with the another wireless communication system in order to complement the communication with the one wireless communication system is performed.

9. The wireless communication terminal of claim 8, further comprising a measuring unit for measuring difference in delay between the one wireless communication system and the another wireless communication system,

wherein the control units performs control such that switching to the another wireless communication system is made when the difference in delay exceeds a threshold value.

10. The wireless communication terminal of claim 8, further comprising a measuring unit for measuring difference in delay between the one wireless communication system and the another wireless communication system,

the control units performs control such that simultaneous communication with the another wireless communication system is performed in order to complement the communication with the one wireless communication system when the difference in delay is equal to or below a threshold value.

11. A method of controlling a wireless communication terminal, which terminal performs communication by one wireless communication system using a broadband and wide-area network where a base station broadcasts allocation information of downlink to a terminal belonging thereto by using an application having real time characteristic, comprising the steps of:

judging, when the wireless communication terminal is performing communication by the one communication system, whether the wireless communication terminal exists at a boundary overlapped with a different sector of the base station for use in communication or at a boundary overlapped with an area of another base station or at an area fringe of the base station for use in communication not overlapped with a sector of the base station for use in communication or an area of another base station; and

controlling, according to the application in use and the results made by the judging unit, such that a handover is performed between base stations in the one wireless communication system, or switching is made to the another wireless communication system using a wide-area network performing a seamless handover between base stations or sectors of a base station, or simultaneous communication with the another wireless communication system is performed in order to complement the communication with the one wireless communication system, or either the uplink or the downlink is switched to the another wireless communication system.

12. The method of controlling a wireless communication terminal of claim 11, further comprising the steps of:

detecting a received signal strength indicator and a signal-to-noise ratio of the wireless communication terminal,

judging, when the received signal strength indicator and the signal-to-noise ratio satisfy predetermined conditions for a predetermined period, that the wireless communication terminal exists at an area fringe of the base station for use in communication not overlapped with a sector of the base station for use in communication or an area of another base station.

13. The method of controlling a wireless communication terminal of claim 12, wherein, when it is judged that the wireless communication terminal exists at an area fringe of the base station for use in communication not overlapped with a sector of the base station for use in communication or an area of another base station of the same wireless network, either the uplink or the downlink is switched to the another wireless communication system.

14. The method of controlling a wireless communication terminal of claim 12, wherein, when communication quality and a received signal strength indicator of the wireless communication terminal are detected and the communication quality and the received signal strength indicator thus detected satisfy first conditions, it is judged that the wireless communication terminal exists at a boundary overlapped with a different sector of the base station for use in communication.

15. The method of controlling a wireless communication terminal of claim 14, wherein, when it is judged that the wireless communication terminal exists at a boundary overlapped with a different sector of the base station for use in communication, switching to the another wireless communication system is made.

16. The method of controlling a wireless communication terminal of claim 14, wherein, when the communication quality and the received signal strength indicator satisfy a second condition in which the received signal strength indicator is set lower than that in the first conditions, it is judged that the wireless communication terminal exists at a boundary overlapped with an area of another base station.

17. The method of controlling a wireless communication terminal, of claim 16, wherein, when it is judged that the application having real time characteristic is a streaming application and that the wireless communication terminal exists at a boundary overlapped with an area of another base station and, a handover between base stations in the one wireless communication system is performed.

18. The method of controlling a wireless communication terminal of claim 16, wherein, in a case where the application having real time characteristic is a VoIP application and it is judged that the wireless communication terminal exists at a boundary overlapped with an area of another base station, either switching to the another wireless communication system is made or simultaneous communication with the another wireless communication system in order to complement the communication with the one wireless communication system is performed.

19. The method of controlling a wireless communication terminal of claim 18, further comprising the steps of:

measuring difference in delay between the one wireless communication system and the another wireless communication system; and

switching to the another wireless communication system when the difference in delay exceeds a threshold value.

20. The method of controlling a wireless communication terminal of claim 18, further comprising the steps of:

measuring difference in delay between the one wireless communication system and the another wireless communication system; and

simultaneously performing communication with the another wireless communication system in order to complement the communication with the one wireless communication system when the difference in delay is equal to or below a threshold value.

21. A wireless communication apparatus connectable to plural wireless communication networks, comprising:

a handover system selection unit for selecting one of

a vertical synchronization system for performing simultaneous handover of vertical links,

an up/down asynchronous system for performing asynchronous handover of the vertical links,

a synchronization connection bandwidth complementary system for simultaneously connecting the terminal to another wireless communication network, while maintaining connection with one wireless communication network currently in use for communication, and performing handover to the another wireless communication network with complementing an insufficient bandwidth, and

an in-the-same-network switching system for performing handover from a base station or sector currently in use for connection to another base station or sector in the same wireless communication network; and

a handover control unit for controllably performing handover by using the handover system selected by the handover system selection unit.

22. The wireless communication apparatus of claim 21, further comprising a policy storing unit for storing a policy regarding handover,

wherein the handover system selection unit selects any one of the handover systems, based on the policy stored in the policy storing unit.

23. The wireless communication apparatus of claim 22, further comprises:

an operation input unit for setting the policy.

24. The wireless communication apparatus of claim 21, further comprising an application information acquisition unit for acquiring, from an application in use for wireless communication, application information of allowable delay time and at least one of a necessary bandwidth of the uplink and a necessary bandwidth of the downlink,

wherein the handover system selection unit selects one of the handover systems on the basis of the application information acquired by the application information acquisition unit.

25. The wireless communication apparatus further of claim 21, further comprising:

a latency storing unit for storing latency required for handover in each wireless communication network of the plural wireless communication networks, and allowable delay time prescribed for each application in use for communication; and

a time comparing unit for comparing latency stored in the latency storing unit with allowable delay time of the application in use for communication,

wherein the handover system selection unit selects one of the handover systems on the basis of the comparison results by the time comparing unit (e.g. whether or not the latency exceeds the allowable delay time).

26. The wireless communication apparatus of claim 21, further comprising:

a delay time measuring unit for measuring average delay time in a wireless communication network currently in use for communication;

a handover counterpart side delay time acquisition unit for acquiring average delay time in another wireless communication network as a candidate of a handover counterpart side;

time difference calculating unit for calculating difference in time between the average delay time measured by the delay time measuring unit and the average delay time acquired by the handover counterpart side delay time acquisition unit; and

a comparison unit for comparing a time interval obtained by adding the larger average delay time of either the wireless communication network currently in use for communication or another wireless communication network as a candidate of the handover counterpart side, to the time difference calculated by the time difference calculating unit, with an allowable delay time of the application,

wherein the handover system selection unit determines, in accordance with a comparison result obtained by the comparison unit, whether the synchronization connection bandwidth complementary system is to be selected or one of the other three systems to be selected.

27. The wireless communication apparatus of claim 21, further comprises:

a communication quality monitoring unit for monitoring communication quality of the uplink and the downlink of the wireless network currently in use for communication, respectively; and

a communication area monitoring unit for monitoring whether or not the terminal is within an area of the another wireless communication network;

wherein the handover system selection unit selects one of the handover systems on the basis of the monitoring results obtained by the communication quality monitoring unit and the communication area monitoring unit.

28. The wireless communication apparatus of claim 21, further comprising:

a consumed electric current value calculating unit for calculating for each wireless communication network a consumed electric current value consumed by communication at each wireless communication network;

wherein the handover system selection unit selects one of the handover systems on the basis of each consumed electric current value calculated by the consumed electric current value calculating unit.

29. The wireless communication apparatus of claim 28, wherein the consumed electric current value calculating unit calculates a consumed electric current value consumed during transmission on the basis of at least transmission output and a transmission bandwidth.

30. A method of controlling a wireless communication apparatus connectable to plural wireless communication networks, comprising the steps of:

selecting a handover system from

a vertical synchronization system for performing simultaneous handover of vertical links,

an up/down asynchronous system for performing asynchronous handover of the vertical links,

a synchronization connection bandwidth complementary system for simultaneously connecting the terminal to another wireless communication network, while maintaining connection with one wireless communication network currently in use for communication, and performing handover to the another wireless communication network with complementing an insufficient bandwidth, and

an in-the-same-network switching system for performing handover from a base station or sector currently in use for connection to another base station or sector in the same wireless communication network; and

controllably performing handover by using the handover system thus selected.