Mobile telecommunication system and channel handoff system between the mobile telecommunication systems

• US 6,778,830 B1
• Filed: 10/25/2000
• Issued: 08/17/2004
• Est. Priority Date: 10/26/1999
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Oizumi, Yasuhiro, Shiotsuki, Hirofumi
• Primary Examiner(s): Gary, Erika
• Assistant Examiner(s): Nguyen, David Q
• Application Number:
  US09/695,069
• Time in Patent Office: 1,392 Days
• Field of Search: 455/436, 455/432.1, 455/439, 455/442, 455/443, 455/403, 455/406
• US Class Current: 455/436
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/38 by fixed network equipment

Abstract

The telecommunication system has mobile telecommunication systems located with their coverage service areas overlapped with each other. Each of the mobile telecommunication systems provides a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit. The radio base station control unit controls communication processing of the radio base station and the mobile telephone terminal. The radio base station control unit has a first means for providing a hard-handoff command signal to command the mobile telephone terminal to execute a hard handoff when the mobile telephone terminal is in the overlapped service area. The hard-handoff command signal is prescribed to become effective at a predetermined time after the mobile telephone terminal receives the hard-handoff command signal. The radio base station control unit has also a second means for providing a hard-handoff command cancellation signal to command the mobile telephone terminal to cancel the hard-handoff command signal when the hard-handoff command signal has not become effective yet. The mobile telephone terminal has means for executing cancellation of the hard-handoff command signal in response to the hard-handoff command cancellation signal.

Claims

1. A telecommunication system having mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal,

said radio base station control unit having a first means for providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff when said mobile telephone terminal is in the overlapped service area, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal;

and a second means for providing a hard-handoff command cancellation signal to command said mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, and

said mobile telephone terminal having means for executing cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal,

wherein said second means has judging means for judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed, and in case that said judging means judges said hard-handoff not to be executed, said radio base station control unit issues said hard-handoff command cancellation signal,

wherein said judging means, while said hard handoff is deferred, compares an intensity of an electric field emitted by a second base station measured by the mobile telephone terminal of interest with a predetermined call-channel-add-on threshold of said second base station and in case that said intensity of the electric field emitted by a second base station is lower than said predetermined threshold, then said radio base station control unit issues said hard-handoff command cancellation signal so that said mobile telephone terminal may remain communicating with a first base station through the current call channel, said first base station referring to a base station that has currently a call channel established to communicate with the mobile telephone terminal of interest and said second base station referring to the base station to which a call channel is to be handed over,

wherein said mobile telephone terminal does not perform any handoff operations in a time range from a first time at which said hard-handoff command signal is received to a second time at which said predetermined time occurs.

2. A telecommunication system having mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal,

said radio base station control unit having a first means for providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff when said mobile telephone terminal is in the overlapped service area, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal;

and a second means for providing a hard-handoff command cancellation signal to command said mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, and

said mobile telephone terminal having means for executing cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal,

wherein said second means has judging means for judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed, and in case that said judging means judges said hard-handoff not to be executed, said radio base station control unit issues said hard-handoff command cancellation signal,

wherein said judging means, while said hard handoff is deferred, compares an intensity of an electric field emitted by a second base station measured by the mobile telephone terminal of interest with a predetermined call-channel-add-on threshold of said second base station and in case that said intensity of the electric field emitted by a second base station is lower than said predetermined threshold, then said radio base station control unit issues said hard-handoff command cancellation signal so that said mobile telephone terminal may remain communicating with a first base station through the current call channel, said first base station referring to a base station that has currently a call channel established to communicate with the mobile telephone terminal of interest and said second base station referring to the base station to which a call channel is to be handed over,

wherein said radio base station control unit issues a reserve channel command to a second radio base station control unit that controls said second base station,

wherein said second base station allocates, based on a command sent from said second radio base station controller, another call channel to be utilized to effectuate communication between said second base station and said mobile telephone terminal starting at a time when said predetermined time occurs and said call channel has been handed over from said call channel of said first base station to said another call channel of said second base station.

3. A telecommunication system having mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal,

said radio base station control unit having a first means for providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff when said mobile telephone terminal is in the overlapped service area, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal;

and a second means for providing a hard-handoff command cancellation signal to command said mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, and

said mobile telephone terminal having means for executing cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal,

wherein said second means has judging means for judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed, and in case that said judging means judges said hard-handoff not to be executed, said radio base station control unit issues said hard-handoff command cancellation signal,

wherein said judging means, while said hard handoff is deferred, compares an intensity of an electric field emitted by a second base station measured by the mobile telephone terminal of interest with a predetermined call-channel-add-on threshold of said second base station and in case that said intensity of the electric field emitted by a second base station is lower than said predetermined threshold, then said radio base station control unit issues said hard-handoff command cancellation signal so that said mobile telephone terminal may remain communicating with a first base station through the current call channel, said first base station referring to a base station that has currently a call channel established to communicate with the mobile telephone terminal of interest and said second base station referring to the base station to which a call channel is to be handed over,

wherein, when said predetermined time has occurred in a case where said hard-handoff command cancellation signal has not been output by said radio base station control unit, said first base station releases said call channel to be used for a future communication with another mobile telephone terminal when a handoff complete command is sent from said second radio base station controller to said radio base station controller, which causes said radio base station controller to output a release channel command to said first base station to thereby release said call channel.

4. A telecommunication system having mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal,

said radio base station control unit having a first means for providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff when said mobile telephone terminal is in the overlapped service area, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal;

and a second means for providing a hard-handoff command cancellation signal to command said mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, and

said mobile telephone terminal having means for executing cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal,

wherein said second means has judging means for judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed, and in case that said judging means judges said hard-handoff not to be executed, said radio base station control unit issues said hard-handoff command cancellation signal,

wherein said judging means, while said hard handoff is deferred, compares an intensity of an electric field emitted by a second base station measured by the mobile telephone terminal of interest with a predetermined call-channel-add-on threshold of said second base station and in case that said intensity of the electric field emitted by a second base station is lower than said predetermined threshold, then said radio base station control unit issues said hard-handoff command cancellation signal so that said mobile telephone terminal may remain communicating with a first base station through the current call channel, said first base station referring to a base station that has currently a call channel established to communicate with the mobile telephone terminal of interest and said second base station referring to the base station to which a call channel is to be handed over,

wherein said mobile telephone terminal is only in communication with said first base station at times prior to said predetermined time occurring, and

wherein said mobile telephone terminal is only in communication with said second base station at times after said predetermined time occurring when no cancellation of said hard-handoff command signal has been received by said mobile telephone terminal prior to said predetermined time occurring.

5. A method of performing a hard handoff of a call of a mobile telephone terminal in a telecommunication system, wherein said telecommunication system has mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal, and wherein a radio base station that currently establishes connection with said mobile telephone terminal through a call channel is referred to as a first base station and a radio base station a call is to be handed over from said first base station is referred to as a second base station, including steps of:

providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal, when said mobile telephone terminal monitors an intensity of an electric field emitted by said first base station lowered below a predetermined channel-drop threshold;

judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed;

providing a hard-handoff command cancellation signal to command a mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, in case that said hard-handoff is judged not to be executed;

issuing said hard-handoff command cancellation signal to said mobile telephone terminal; and

controlling said mobile telephone terminal to execute cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal,

wherein said mobile telephone terminal does not perform any handoff operations in a time range from a first time at which said hard-handoff command signal is received to a second time at which said predetermined time occurs.

6. A method of performing a hard handoff of a call of a mobile telephone terminal in a telecommunication system, wherein said telecommunication system has mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal, and wherein a radio base station that currently establishes connection with said mobile telephone terminal through a call channel is referred to as a first base station and a radio base station a call is to be handed over from said first base station is referred to as a second base station, including steps of:

providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal, when said mobile telephone terminal monitors an intensity of an electric field emitted by said first base station lowered below a predetermined channel-drop threshold;

judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed;

providing a hard-handoff command cancellation signal to command a mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, in case that said hard-handoff is judged not to be executed;

issuing said hard-handoff command cancellation signal to said mobile telephone terminal;

controlling said mobile telephone terminal to execute cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal;

issuing, by said radio base station control unit, a reserve channel command to a second radio base station control unit that controls said second base station; and

allocating, by said second base station based on a command sent from said second radio base station controller, another call channel to be utilized to effectuate communication between said second base station and said mobile telephone terminal starting at a time when said predetermined time occurs and said call channel has been handed over from said call channel of said first base station to said another call channel of said second base station,

wherein said step of judging includes steps of;

comparing an intensity of an electric field emitted by a second base station measured by the mobile telephone terminal of interest with a predetermined call-channel-add-on threshold of said second base station, while said hard handoff is deferred; and

issuing said hard-handoff command cancellation signal so that said mobile telephone terminal may remain communicating with a first base station through the current call channel, in case that said intensity of the electric field emitted by a second base station is lower than said predetermined threshold.

7. A method of performing a hard handoff of a call of a mobile telephone terminal in a telecommunication system, wherein said telecommunication system has mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal, and wherein a radio base station that currently establishes connection with said mobile telephone terminal through a call channel is referred to as a first base station and a radio base station a call is to be handed over from said first base station is referred to as a second base station, including steps of:

providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal, when said mobile telephone terminal monitors an intensity of an electric field emitted by said first base station lowered below a predetermined channel-drop threshold;

judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed;

providing a hard-handoff command cancellation signal to command a mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, in case that said hard-handoff is judged not to be executed;

issuing said hard-handoff command cancellation signal to said mobile telephone terminal;

controlling said mobile telephone terminal to execute cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal;

releasing, when said predetermined time has occurred in a case where said hard-handoff command cancellation signal has not been output by said radio base station control unit, said call channel to be used for a future communication with another mobile telephone terminal when a handoff complete command is sent from said second radio base station controller to said radio base station controller; and

outputting, by said radio base station controller, a release channel command to said first base station, to thereby release said call channel,

wherein said step of judging includes steps of;

comparing an intensity of an electric field emitted by a second base station measured by the mobile telephone terminal of interest with a predetermined call-channel-add-on threshold of said second base station, while said hard handoff is deferred; and

issuing said hard-handoff command cancellation signal so that said mobile telephone terminal may remain communicating with a first base station through the current call channel, in case that said intensity of the electric field emitted by a second base station is lower than said predetermined threshold.

8. A method of performing a hard handoff of a call of a mobile telephone terminal in a telecommunication system, wherein said telecommunication system has mobile telecommunication systems located with their coverage service areas overlapped with each other, each of said mobile telecommunication systems providing a communication service to a mobile telephone terminal through a radio base station and a radio base station control unit to control communication processing of said radio base station and said mobile telephone terminal, and wherein a radio base station that currently establishes connection with said mobile telephone terminal through a call channel is referred to as a first base station and a radio base station a call is to be handed over from said first base station is referred to as a second base station, including steps of:

providing a hard-handoff command signal to command said mobile telephone terminal to execute a hard handoff, said hard-handoff command signal being prescribed to become effective at a predetermined time after said mobile telephone terminal receives said hard-handoff command signal, when said mobile telephone terminal monitors an intensity of an electric field emitted by said first base station lowered below a predetermined channel-drop threshold;

judging whether or not the hard handoff that has been commanded through said hard-handoff command signal and is now deferred until said predetermined time is to be executed;

providing a hard-handoff command cancellation signal to command a mobile telephone terminal to cancel said hard-handoff command signal when said hard-handoff command signal has not become effective yet, in case that said hard-handoff is judged not to be executed;

issuing said hard-handoff command cancellation signal to said mobile telephone terminal;

controlling said mobile telephone terminal to execute cancellation of said hard-handoff command signal in response to said hard-handoff command cancellation signal,

wherein said step of judging includes steps of;

comparing an intensity of an electric field emitted by a second base station measured by the mobile telephone terminal of interest with a predetermined call-channel-add-on threshold of said second base station, while said hard handoff is deferred; and

issuing said hard-handoff command cancellation signal so that said mobile telephone terminal may remain communicating with a first base station through the current call channel, in case that said intensity of the electric field emitted by a second base station is lower than said predetermined threshold,

wherein said mobile telephone terminal is only in communication with said first base station at times prior to said predetermined time occurring, and

wherein said mobile telephone terminal is only in communication with said second base station at times after said predetermined time occurring when no cancellation of said hard-handoff command signal has been received by said mobile telephone terminal prior to said predetermined time occurring.