JP4793573B2 - Mobile communication system, radio base station control apparatus, and compressed mode activation method - Google Patents

Description

  The present invention relates to a mobile communication system capable of performing inter-frequency handover or inter-system handover, a radio base station control device, and a compressed mode activation method.

  In a mobile communication system constructed for communication using a mobile terminal or the like that can be moved, when a connection destination is changed from a radio base station to which the mobile terminal is connected to another radio base station, Over technique is used.

  At this time, different frequency bands are used for connection to the connection destination before the change and the connection destination after the change, but it is desirable to select a frequency band having a good propagation state. Therefore, it is necessary to measure the propagation status of each frequency band. To measure the propagation status of each frequency band, a technique such as compressed mode using a pilot signal is used. (For example, refer to Patent Document 1).

  This compressed mode is used, for example, to realize a handover from a radio base station of a UMTS (Universal Mobile Telecommunications System) network to another radio base station such as a UMTS network or a GSM (Global System for Mobile Communications) network. Technology. By periodically compressing and transmitting information at the mobile terminal, a transmission gap (vacant time) in which data transmission is not performed is created, and the reception frequency is switched between the gaps to propagate in different frequency bands. Is measured using a pilot signal. The activation of the compressed mode is performed by the radio base station control apparatus for the radio base station and the mobile terminal as necessary.

  FIG. 11 shows an example of a conventional mobile communication system.

  The mobile communication system shown in FIG. 11 is composed of a UMTS network 1001 and a GSM network 1002 which is a network different from the UMTS network 1001, and a radio base station 1003 covers the UMTS network 1001. A radio base station 1004 covers the GSM network 1002. A mobile terminal 1005 is moving from the UMTS network 1001 to the GSM network 1002. At that time, a pilot signal 1006 is transmitted from the radio base station 1004 to the mobile terminal 1005.

  At this time, when the mobile terminal 1005 moves from the UMTS network 1001 to the GSM network 1002, the compressed mode in the mobile terminal 1005 is activated by a radio base station control device (not shown) and is transmitted from the radio base station 1004. The propagation status is measured by the mobile terminal 1005 using the signal 1006.

There are mobile terminals that can measure the propagation status in different frequency bands without using the compressed mode, but this is out of the scope of the present invention.
Japanese Patent Application Laid-Open No. 2003-079936

  However, if the compressed mode is started in many mobile terminals by starting the compressed mode without an upper limit by the radio base station control device, interference with signals transmitted and received by other mobile terminals may occur. There is a problem that it increases.

  In addition, when the compressed mode is activated in many mobile terminals or many links in order to transmit the information using temporarily high transmission power in order to prevent quality degradation due to compressed transmission of information to be transmitted. However, there is a problem in that the amount of interference with signals transmitted and received by other mobile terminals or other links increases and the radio capacity decreases.

  The present invention has been made in view of the problems of the conventional technology as described above, and is capable of suppressing a decrease in radio capacity due to interference with other signals, and radio base station control. An object is to provide a device and a compressed mode starting method.

In order to achieve the above object, the present invention provides:
A mobile communication system capable of hardover,
When a compressed mode activation trigger for a mobile terminal is detected, the number of compressed modes being activated is compared with a preset activation threshold, and the number of compressed modes being activated is smaller than the activation threshold. A radio base station controller that activates a compressed mode for the mobile terminal;
A radio base station that is connected to the radio base station controller and forms a cell capable of communicating by radio waves and communicates with the mobile terminal;

  In addition, when the radio base station control device detects the compressed mode activation trigger of the mobile terminal, and the number of compressed modes being activated is equal to or greater than the activation threshold, the radio base station control device moves when the compressed mode is activated. When there is a mobile terminal with a priority lower than the priority based on the radio wave condition in the mobile terminal among the terminals, the compressed mode is stopped for the mobile terminal with the lowest priority among the mobile terminals with the lower priority It is characterized by doing.

  Further, the radio base station control apparatus is characterized in that the mobile terminal that has stopped the compressed mode is handed over.

Further, a radio base station control device that activates a compressed mode for a mobile terminal in a mobile communication system,
When detecting the compressed mode activation trigger for the mobile terminal, the number of compressed modes being activated is compared with a preset activation threshold, and the number of compressed modes being activated is smaller than the activation threshold. In this case, the compressed mode is activated for the mobile terminal.

  In addition, when a compressed mode activation trigger of the mobile terminal is detected, if the number of compressed modes being activated is equal to or greater than the activation threshold, radio waves of the mobile terminal among the mobile terminals that are activated in the compressed mode are detected. When there is a mobile terminal with a priority lower than the priority based on the situation, the compressed mode is stopped for the mobile terminal with the lowest priority among the mobile terminals with the lower priority.

  Further, the mobile terminal that has stopped the compressed mode is handed over.

Also, a compressed mode starting method for starting a compressed mode for a mobile terminal in a mobile communication system,
When detecting a compressed mode activation trigger for the mobile terminal, a process of comparing the number of compressed modes being activated with a preset activation threshold;
And a process of starting the compressed mode for the mobile terminal when the number of compressed modes being activated is smaller than the activation threshold.

  In addition, when a compressed mode activation trigger of the mobile terminal is detected, if the number of compressed modes being activated is equal to or greater than the activation threshold, radio waves of the mobile terminal among the mobile terminals that are activated in the compressed mode are detected. When there is a mobile terminal with a priority lower than the priority based on the situation, the mobile terminal has a process of stopping the compressed mode for the mobile terminal with the lowest priority among the low priority mobile terminals.

  The mobile terminal having stopped the compressed mode has a process for performing a handover.

  In the present invention configured as described above, when a compressed mode activation trigger for a mobile terminal is detected, the number of compressed modes being activated is compared with a preset activation threshold, Only when the number of compressed modes is smaller than the activation threshold, the compressed mode is activated for the mobile terminal.

  As a result, the possibility of interference with other signals caused by the compressed mode activation can be reduced, and the communication quality in each cell can be maintained above a certain level.

  As described above, in the present invention, when a compressed mode activation trigger for a mobile terminal is detected, the number of compressed modes being activated is compared with a preset activation threshold, and the compressed mode being activated is Since the compressed mode is activated for the mobile terminal only when the number is smaller than the activation threshold, it is possible to suppress a decrease in radio capacity due to interference with other signals.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing an embodiment of a mobile communication system according to the present invention.

  As shown in FIG. 1, the present embodiment includes a radio base station control device 101 and radio base stations 102-1 to 102-3. An area where the radio base station 102-1 can communicate with radio waves is a cell 103-1, an area where the radio base station 102-2 can communicate with radio waves is a cell 103-2, and the radio base station 102 -3 is an area in which radio waves can be communicated as a cell 103-3. Further, the mobile terminal 104 is moving between the cells 103-1 to 103-3. The radio base station control apparatus 101 controls the radio base stations 102-1 to 102-3. Here, although the number of the radio base stations 102-1 to 102-3 is shown as three, the number is not particularly limited, and may be two, or a plurality of three or more.

  FIG. 2 is a block diagram showing a first configuration example of the radio base station control apparatus 101 shown in FIG.

  As illustrated in FIG. 2, the radio base station control apparatus 101 includes a communication unit 110, a comparison unit 111, a counter 112, a storage unit 113, and an activation control unit 114.

  The communication unit 110 communicates with the radio base stations 102-1 to 102-3.

  The comparison unit 111 compares the value indicated by the counter 112 with a threshold value stored in advance in the storage unit 113.

  The counter 112 is a counter indicating the number of links in which the compressed mode is activated.

  The storage unit 113 stores in advance a threshold value of the number of links that can activate the compressed mode.

  The activation control unit 114 controls the activation of the compressed mode for the mobile terminal 104 via the radio base stations 102-1 to 102-3 based on the comparison result in the comparison unit 111.

  Note that the configuration shown in FIG. 2 shows only the components related to the present invention.

  The compressed mode activation method in the radio base station control apparatus 101 shown in FIG. 2 provided in the mobile communication system shown in FIG. 1 will be described below.

  FIG. 3 is a flowchart for explaining a compressed mode activation method in radio base station control apparatus 101 shown in FIG. 2 provided in the mobile communication system shown in FIG.

  As an initial setting, the number of links that can be activated in the compressed mode is stored in advance in the storage unit 113 as an activation threshold (hereinafter referred to as MAX_CM).

  First, when the radio base station control apparatus 101 detects the trigger for starting the compressed mode for the mobile terminal 104 (step S1), the value currently indicated by the counter 112 and the MAX_CM stored in the storage unit 113 in advance. Are compared by the comparison unit 111. The detection process in step S1 here is the same as the conventional process, and a notification that the quality of the frequency used in the mobile terminal 104 has deteriorated is transmitted from the mobile terminal 104 to the radio base station control apparatus 101. The notification is received by the radio base station control apparatus 101, the call establishment time is detected, and the like. The counter 112 manages the number of compressed mode activation links (hereinafter referred to as CM_UL) in the uplink direction (Uplink) from the mobile terminal 104 to the radio base station control apparatus 101, and the radio base station control apparatus 101. It is desirable to separately provide one that manages the number of links in the compressed mode activation (hereinafter referred to as CM_DL) in the downlink direction from the mobile terminal 104 to the mobile terminal 104 (Downlink). There are mobile terminals that require activation only in the uplink direction and mobile terminals that require activation only in the downlink direction when the compressed mode is activated, and the number of mobile terminals that are activated in the compressed mode in the uplink direction and downlink This is because the number of mobile terminals in which the compressed mode is activated in the direction does not always match.

  Although the comparison between the CM_UL and the MAX_CM and the comparison between the CM_DL and the MAX_CM are performed by the comparison unit 111, either comparison may be performed first. Here, a case where CM_UL and MAX_CM are compared first will be described as an example.

  CM_UL and MAX_CM are compared by comparison unit 111 (step S2), and if it is determined that CM_UL is not smaller than MAX_CM, the compressed mode is not activated and the process ends. In other words, if the number of links that activate the compressed mode increases further, the number of links that are in the compressed mode activation exceeds the number of links that the compressed mode can be activated. Avoid it.

  If it is determined in step S2 that CM_UL is smaller than MAX_CM, CM_DL and MAX_CM are compared by comparison unit 111 (step S3). If it is determined that CM_DL is not smaller than MAX_CM, the compressed mode is not activated and the process ends. In other words, as with the comparison between CM_UL and MAX_CM, if the number of links that activate the compressed mode further increases, the number of links during the activation of the compressed mode will exceed the number of links that can activate the compressed mode. It avoids starting a new compressed mode.

  If it is determined in step S3 that CM_DL is smaller than MAX_CM, the value of the counter 112 is incremented by one (step S4), and the compressed mode is transferred from the activation control unit 114 to the mobile terminal 104 via the communication unit 110. It is activated (step S5). In other words, if there is still a margin in the number of links where the compressed mode can be activated, it is allowed to newly activate the compressed mode.

  While the above-described processing is performed, when the radio base station control apparatus 101 detects a compressed mode stop trigger for the mobile terminal 104, the value of the counter 112 is decremented by one. The detection process of the compressed mode stop trigger is the same as the conventional process.

  Further, when a soft handover activation trigger is detected for the mobile terminal 104 in compressed mode activation by the radio base station controller 101, the active set cell of the mobile terminal 104 in the link in compressed mode activation is Since it is updated, CM_UL and CM_DL need to be updated. At this time, when the cell is deleted from the active set cell of the mobile terminal 104, the values of CM_UL and CM_DL are decreased for the link in which the compressed mode is activated. On the other hand, when a cell is added to the active set cell of the mobile terminal 104, the values of CM_UL and CM_DL are increased for the link in which the compressed mode is activated. Here, when a new cell is added to the Active set cell, the value of CM_UL or CM_DL may exceed MAX_CM, but in this case, the activated compressed mode is not stopped. This is because, since soft handover frequently occurs in the UMTS network, it is not preferable from the viewpoint of traffic to send a message for stopping the compressed mode each time.

  Thus, only when the number of compressed mode activation links that may cause interference with other signals is preset as a threshold and the current number of compressed mode activation links is smaller than the set threshold. Since the compressed mode is activated, the possibility of interference with other signals caused by the compressed mode activation can be reduced, and the communication quality in each cell can be maintained above a certain level.

  FIG. 4 is a block diagram showing a second configuration example of the radio base station control apparatus 101 shown in FIG.

  In the radio base station control apparatus 101 shown in FIG. 4, a propagation delay time acquisition unit 115 is added to the first configuration shown in FIG.

  The propagation delay time acquisition unit 115 calculates the propagation delay time between the radio base stations 102-1 to 102-3 and the mobile terminal 104 measured by the radio base stations 102-1 to 102-3. 1 to 102-3 through the communication unit 110.

  The compressed mode starting method in the radio base station control apparatus 101 shown in FIG. 4 provided in the mobile communication system shown in FIG. 1 will be described below.

  FIG. 5 is a flowchart for explaining a compressed mode activation method in radio base station control apparatus 101 shown in FIG. 4 provided in the mobile communication system shown in FIG.

  As an initial setting, the number of links that can be activated in the compressed mode is stored in advance in the storage unit 113 as an activation threshold (hereinafter referred to as MAX_CM).

  First, when the radio base station control apparatus 101 detects a trigger for starting the compressed mode for the mobile terminal 104 (step S11), the value currently indicated by the counter 112 and the MAX_CM stored in the storage unit 113 in advance. Are compared by the comparison unit 111. The detection process of step S11 here is the same as the conventional detection process described using the flowchart of FIG.

  After that, as in the process described with reference to the flowchart of FIG. 3, the comparison between CM_UL and MAX_CM and the comparison between CM_DL and MAX_CM are performed by the comparison unit 111, which comparison is performed first. It doesn't matter. Here, a case where CM_UL and MAX_CM are compared first will be described as an example.

  CM_UL and MAX_CM are compared by comparison unit 111 (step S12), and if it is determined that CM_UL is smaller than MAX_CM, CM_DL and MAX_CM are compared by comparison unit 111 (step S13).

  Further, if it is determined that CM_DL is smaller than MAX_CM, the current value of counter 112 is incremented by 1 (step S14), and compressed mode is activated from activation control unit 114 to mobile terminal 104 via communication unit 110. (Step S15). In other words, if there is still a margin in the number of links where the compressed mode can be activated, it is allowed to newly activate the compressed mode.

  On the other hand, if it is determined in step S12 that CM_UL is not smaller than MAX_CM, or if it is determined in step S13 that CM_DL is not smaller than MAX_CM, the propagation delay time acquisition unit 115 causes the wireless base station to The propagation delay time between the radio base stations 102-1 to 102-3 and the mobile terminal 104 measured by the stations 102-1 to 102-3 is changed from the radio base stations 102-1 to 102-3 to the communication unit 110. (Step S16).

  Then, the activation control unit 114 compares the acquired propagation delay time with the propagation delay times of other mobile terminals already stored in the storage unit 113 (step S17).

  FIG. 6 is a diagram showing propagation delay times of other mobile terminals already stored in the storage unit 113 shown in FIG.

  The propagation delay times of other mobile terminals already stored in the storage unit 113 shown in FIG. 4 are arranged in order from the longest propagation delay time as shown in FIG. Has the highest priority, and the priority is set lower as the propagation delay time becomes shorter. Among these, five of the longest propagation delay times acquired after the compressed mode activation by the radio base station control apparatus 101 is stored. For example, the mobile terminal having the terminal number “090-1111-2222” having the longest propagation delay time “500 ms” is stored as the priority “1” having the highest priority. In addition, the mobile terminal having the terminal number “090-2222-3333” having the second longest propagation delay time “450 ms” is stored as the priority “2” having the second highest priority. In addition, the mobile terminal having the terminal number “090-3333-4444” having the third longest propagation delay time “420 ms” is stored as the priority “3” having the third highest priority. In addition, the mobile terminal having the terminal number “090-4444-5555” having the fourth longest propagation delay time “400 ms” is stored as the priority “4” having the fourth highest priority. In addition, the mobile terminal having the terminal number “090-5555-6666” having the fifth longest propagation delay time “360 ms” is stored as the priority “5” having the fifth highest priority. In addition, although the structure in the memory | storage part 113 shown in FIG. 6 has a structure where five mobile terminals are memorize | stored, the number is not specifically limited here.

  For example, when the propagation delay time acquired by the propagation delay time acquisition unit 115 is “390 ms”, the propagation delay time “360 ms” having the priority “5” illustrated in FIG. The delay time “390 ms” is registered as the priority “5” together with the mobile terminal number, and stored in the storage unit 113 (step S18). Then, the shortest propagation delay time “360 ms” among the stored propagation delay times that has been the priority “5” is deleted (step S19). Then, the compressed mode is stopped for the mobile terminal having the deleted propagation delay time (step S20).

  Thereafter, the compressed mode is activated for the mobile terminal 104 whose acquired propagation delay time is “390 ms” (step S15).

  On the other hand, if the acquired propagation delay time is shorter than any of the propagation delay times of other mobile terminals already stored in the storage unit 113 in step S17, the compressed mode activation to the mobile terminal 104 is The process ends without being performed.

  Note that the value of the propagation delay time shown in FIG. 6 is a value for convenience of explanation, and is different from an actual measurement value.

  Further, here, as the priority of the mobile terminal, the case where the longest propagation delay time is the highest priority and the priority is set low as the propagation delay time becomes short has been described as an example, The one with the shortest propagation delay time may have the highest priority, and the priority may be set lower as the propagation delay time becomes longer.

  Further, a threshold is set for the propagation delay time, and the priority is determined to be equal to or higher than a predetermined value only when the propagation delay time acquired by the propagation delay time acquisition unit 115 is longer than the threshold, The compressed mode may be activated. Further, only when the propagation delay time acquired by the propagation delay time acquisition unit 115 is shorter than the threshold value, the priority is determined to be equal to or higher than a predetermined value, and the compressed mode is activated to the mobile terminal having the acquired propagation delay time. There may be. That is, when it is determined that the priority of a mobile terminal is equal to or higher than a predetermined threshold, the compressed mode may be activated for the mobile terminal. In this case, activation of the compressed mode may be stopped for the mobile terminal with the lowest priority among the mobile terminals that are currently in the compressed mode.

  In this way, the propagation delay time is acquired, and the acquired propagation delay time is used as the priority for starting the compressed mode for the mobile terminal, thereby starting the compressed mode only for the mobile terminal having a high priority. It becomes possible.

  In addition, a mobile terminal that uses the received field strength of the mobile terminal as a priority may be considered.

  FIG. 7 is a block diagram showing a third configuration example of the radio base station control apparatus 101 shown in FIG.

  In the radio base station control apparatus 101 illustrated in FIG. 7, the propagation delay time acquisition unit 115 in the second configuration example illustrated in FIG. 4 is replaced with an electric field strength acquisition unit 116.

  The electric field strength acquisition unit 116 acquires the received electric field strength of the signal at the mobile terminal 104 from the radio base stations 102-1 to 102-3 via the communication unit 110.

  The compressed mode starting method in the radio base station control apparatus 101 shown in FIG. 7 provided in the mobile communication system shown in FIG. 1 will be described below.

  FIG. 8 is a flowchart for explaining a compressed mode activation method in radio base station control apparatus 101 shown in FIG. 7 provided in the mobile communication system shown in FIG.

  As an initial setting, the number of links that can activate the compressed mode is stored in advance in the storage unit 113 as an activation threshold (MAX_CM).

  First, when the radio base station control apparatus 101 detects a trigger for starting the compressed mode for the mobile terminal 104 (step S21), the value currently indicated by the counter 112 and the MAX_CM stored in the storage unit 113 in advance are stored. Are compared by the comparison unit 111. The detection process of step S21 here is the same as the conventional detection process described using the flowchart of FIG.

  After that, as in the process described with reference to the flowchart of FIG. 3, the comparison between CM_UL and MAX_CM and the comparison between CM_DL and MAX_CM are performed by the comparison unit 111, which comparison is performed first. It doesn't matter. Here, a case where CM_UL and MAX_CM are compared first will be described as an example.

  CM_UL and MAX_CM are compared by comparison unit 111 (step S22), and if it is determined that CM_UL is smaller than MAX_CM, CM_DL and MAX_CM are compared by comparison unit 111 (step S23).

  Further, if it is determined that CM_DL is smaller than MAX_CM, the current value of counter 112 is incremented by 1 (step S24), and compressed mode is activated from activation control unit 114 to mobile terminal 104 via communication unit 110. (Step S25). In other words, if there is still a margin in the number of links where the compressed mode can be activated, it is allowed to newly activate the compressed mode.

  On the other hand, if it is determined in step S22 that CM_UL is not smaller than MAX_CM, or if it is determined in step S23 that CM_DL is not smaller than MAX_CM, the electric field strength acquisition unit 116 causes the mobile terminal 104 to The received electric field strength of the signal received by the wireless base station 102-1 to 102-3 is acquired via the communication unit 110 (step S26).

  Then, the acquired received electric field strength and the received electric field strength of another mobile terminal already stored in the storage unit 113 are compared by the activation control unit 114 (step S27).

  FIG. 9 is a diagram showing received electric field strengths of other mobile terminals already stored in the storage unit 113 shown in FIG.

  The received electric field strengths of other mobile terminals already stored in the storage unit 113 shown in FIG. 4 are arranged in order from the lowest received electric field strength as shown in FIG. Has the highest priority, and the priority is set lower as the received electric field strength becomes stronger. Of these, five of the received electric field strengths that are weak after the compressed mode activation by the radio base station control apparatus 101 is stored. For example, the mobile terminal having the terminal number “090-1111-0000” having the weakest received electric field strength “12” is stored as the priority “1” having the highest priority. In addition, the mobile terminal having the terminal number “090-2222-1111” having the second lowest received electric field strength “15” is stored as the priority “2” having the second highest priority. In addition, the mobile terminal having the terminal number “090-3333-2222” having the second lowest received electric field strength “20” is stored as the priority “3” having the third highest priority. In addition, the mobile terminal having the terminal number “090-4444-3333” having the received electric field strength “21” that is the fourth weakest is stored as the priority “4” having the fourth highest priority. Further, the mobile terminal having the terminal number “090-5555-4444” having the reception field strength “23” having the fifth weakest reception field is stored as the priority “5” having the fifth highest priority. In addition, although the structure in the memory | storage part 113 shown in FIG. 9 is a structure where five mobile terminals are memorize | stored, the number is not specifically limited here.

  For example, when the received electric field strength acquired by the electric field strength acquiring unit 116 is “22”, the received electric field strength “23” having the priority “5” shown in FIG. The strength “22” is registered as the priority “5” together with the mobile terminal number and is stored in the storage unit 113 (step S28). Then, the strongest received electric field strength “23” among the stored received electric field strengths having the priorities “5” is deleted (step S29). Then, the compressed mode is stopped for the mobile terminal having the deleted received electric field strength (step S30).

  Thereafter, the compressed mode is activated for the mobile terminal 104 whose acquired received electric field strength is “22” (step S25).

  On the other hand, if the received electric field strength acquired in step S27 is stronger than any of the received electric field strengths of other mobile terminals already stored in the storage unit 113, the compressed mode activation to the mobile terminal 104 is activated. The process ends without being performed.

  Note that the value of the received electric field strength shown in FIG. 9 is a value for convenience of explanation, and is different from the actual measured value.

  Further, here, as a priority of the mobile terminal, the case where the weakest received electric field strength has the highest priority, and the case where the priority is set lower as the received electric field strength becomes stronger has been described as an example, The highest received electric field strength may have the highest priority, and the lower priority may be set as the received electric field strength becomes weaker.

  In addition, a threshold is set for the received electric field strength, and only when the received electric field strength acquired by the electric field strength acquiring unit 116 is weaker than the threshold, the priority is determined to be greater than or equal to a predetermined value, and the mobile terminal having the acquired received electric field strength is connected It may activate the presto mode. Further, only when the received electric field strength acquired by the electric field strength acquiring unit 116 is stronger than the threshold value, the priority is determined to be equal to or higher than a predetermined value, and the compressed mode is activated to the mobile terminal having the acquired received electric field strength. May be. That is, the compressed mode may be activated for the mobile terminal only when the priority of the mobile terminal is determined to be greater than or equal to a predetermined threshold. In this case, activation of the compressed mode may be stopped with respect to the mobile terminal having the lowest priority among the mobile terminals currently activated in the compressed mode.

  In this way, the received electric field strength is acquired, and the acquired received electric field strength is used as the priority for starting the compressed mode to the mobile terminal, thereby starting the compressed mode only for the mobile terminal having a higher priority. It becomes possible.

  As described above, the priority used as a reference for starting the compressed mode for the mobile terminal is described as an example when the propagation delay time indicating the radio wave condition of the mobile terminal is used and when the received electric field strength is used. However, other devices may be used as long as the priorities of the mobile terminals can be identified. For example, the priority may be set in advance using an identification number (telephone number or the like) unique to the mobile terminal, and the above-described processing may be performed based on the set priority.

  In addition, when the compressed mode is activated with the above-mentioned priority, a method is also considered in which the compressed mode is stopped and the handover is forcibly performed for a mobile terminal with a low priority among the mobile terminals that are in the compressed mode activation. It is done.

  FIG. 10 is a flowchart for explaining a method for forcibly handing over the compressed mode to a mobile terminal having a low priority among the mobile terminals in which the compressed mode is activated.

  As an initial setting, the number of links that can activate the compressed mode is stored in advance in the storage unit 113 as an activation threshold (MAX_CM).

  First, when the radio base station control apparatus 101 detects a trigger for starting the compressed mode for the mobile terminal 104 (step S31), the value currently indicated by the counter 112 and the MAX_CM stored in the storage unit 113 in advance are stored. Are compared by the comparison unit 111. The detection process of step S31 here is the same as the conventional detection process described using the flowchart of FIG.

  After that, as in the process described with reference to the flowchart of FIG. 3, the comparison between CM_UL and MAX_CM and the comparison between CM_DL and MAX_CM are performed by the comparison unit 111, which comparison is performed first. It doesn't matter. Here, a case where CM_UL and MAX_CM are compared first will be described as an example.

  CM_UL and MAX_CM are compared by comparison unit 111 (step S32), and if it is determined that CM_UL is smaller than MAX_CM, CM_DL and MAX_CM are compared by comparison unit 111 (step S33).

  Further, if it is determined that CM_DL is smaller than MAX_CM, the value of the counter 112 is incremented by 1 (step S34), and the compressed mode is activated from the activation control unit 114 to the mobile terminal 104 via the communication unit 110. (Step S35). In other words, if there is still a margin in the number of links where the compressed mode can be activated, it is allowed to newly activate the compressed mode.

  On the other hand, if it is determined in step S32 that CM_UL is not smaller than MAX_CM, or if it is determined in step S33 that CM_DL is not smaller than MAX_CM, the compressed mode is currently activated. It is determined whether there is a mobile terminal that has a lower priority than the mobile terminal and can be handed over (step S36). Note that a method for searching for a mobile terminal that is in a radio wave condition that can be handed over is the same as the conventional method, and thus will not be described in detail here. Further, this priority is the same as that of the mobile terminal described above.

  When it is determined that there is no mobile terminal in which the compressed mode is currently activated and has a lower priority than the mobile terminal and can be handed over, the compressed mode activation to the mobile terminal 104 is The process ends without being performed.

  On the other hand, if it is determined that there is a mobile terminal that is lower in priority than the mobile terminal 104 and can be handed over among the mobile terminals that are currently in the compressed mode, the mobile terminal 104 is registered (step In S37, a mobile terminal having a lower priority than the mobile terminal 104 and capable of handover is deleted from mobile terminals whose compressed mode is currently activated (step S38). Then, the compressed mode is stopped for the mobile terminal that has a lower priority than the mobile terminal 104 and can be handed over (step S39), and the mobile terminal is forcibly handed over (step S40). Thereafter, the compressed mode is activated from the activation control unit 114 to the mobile terminal 104 via the communication unit 110 (step S35).

  In the above-described processing, the number of compressed mode activations may be managed only for one or several events that require the compressed mode.

It is a figure which shows one Embodiment of the mobile communication system of this invention. FIG. 2 is a block diagram illustrating a first configuration example of a radio base station control device illustrated in FIG. 1. 3 is a flowchart for explaining a compressed mode activation method in the radio base station control device shown in FIG. 2 provided in the mobile communication system shown in FIG. FIG. 3 is a block diagram showing a second configuration example of the radio base station control device shown in FIG. 1. 5 is a flowchart for explaining a compressed mode starting method in the radio base station control device shown in FIG. 4 provided in the mobile communication system shown in FIG. 1; It is a figure which shows the propagation delay time of the other mobile terminal already memorize | stored in the memory | storage part shown in FIG. FIG. 5 is a block diagram showing a third configuration example of the radio base station control device shown in FIG. 1. 8 is a flowchart for explaining a compressed mode activation method in the radio base station control device shown in FIG. 7 provided in the mobile communication system shown in FIG. 1; It is a figure which shows the received electric field strength of the other mobile terminal already memorize | stored in the memory | storage part shown in FIG. It is a flowchart for demonstrating the method to stop a compressed mode and to perform a hand-over forcibly about a mobile terminal with a low priority among the mobile terminals in which compressed mode is started. It is a figure which shows an example of the form of the conventional mobile communication system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Radio base station control apparatus 102-1 to 102-3 Radio base station 103-1 to 103-3 Cell 104 Mobile terminal 110 Communication part 111 Comparison part 112 Counter 113 Storage part 114 Startup control part 115 Propagation delay time acquisition part 116 Electric field Strength acquisition unit

Claims (9)

A mobile communication system capable of hardover,
When a compressed mode activation trigger for a mobile terminal is detected, the number of compressed modes being activated is compared with a preset activation threshold, and the number of compressed modes being activated is smaller than the activation threshold. A radio base station controller that activates a compressed mode for the mobile terminal;
A mobile communication system comprising: a radio base station that is connected to the radio base station controller and constitutes a cell capable of communicating by radio waves and communicates with the mobile terminal. The mobile communication system according to claim 1, wherein
When the radio base station controller detects the compressed mode activation trigger of the mobile terminal and the number of compressed modes being activated is equal to or greater than the activation threshold, the radio base station control device When there is a mobile terminal with a priority lower than the priority based on the radio wave condition in the mobile terminal, the compressed mode is stopped for the mobile terminal with the lowest priority among the mobile terminals with the lower priority. A mobile communication system. The mobile communication system according to claim 2, wherein
The radio base station control apparatus performs handover to a mobile terminal that has stopped the compressed mode. A radio base station controller that activates a compressed mode for a mobile terminal in a mobile communication system,
When detecting the compressed mode activation trigger for the mobile terminal, the number of compressed modes being activated is compared with a preset activation threshold, and the number of compressed modes being activated is smaller than the activation threshold. In this case, a radio base station controller that activates a compressed mode for the mobile terminal. In the radio base station control device according to claim 4,
When the compressed mode activation trigger of the mobile terminal is detected, if the number of compressed modes being activated is equal to or greater than the activation threshold, the radio terminal of the mobile terminal in compressed mode activation Radio base station control, wherein when there is a mobile terminal with a priority lower than the priority based on, the compressed mode is stopped for the mobile terminal with the lowest priority among the mobile terminals with the lower priority apparatus. In the radio base station control device according to claim 5,
A radio base station controller, wherein a mobile terminal that has stopped the compressed mode is handed over. A compressed mode activation method for activating a compressed mode for a mobile terminal in a mobile communication system,
When detecting a compressed mode activation trigger for the mobile terminal, a process of comparing the number of compressed modes being activated with a preset activation threshold;
A compressed mode activation method comprising: a process of activating a compressed mode for the mobile terminal when the number of compressed modes being activated is smaller than the activation threshold. In the compressed mode starting method according to claim 7,
When the compressed mode activation trigger of the mobile terminal is detected, if the number of compressed modes being activated is equal to or greater than the activation threshold, the radio terminal of the mobile terminal in compressed mode activation A compressed mode activation method comprising a process of stopping a compressed mode for a mobile terminal having the lowest priority among the low priority mobile terminals when a mobile terminal having a lower priority than a priority based on the base station exists. In the compressed mode starting method according to claim 8,
A compressed mode activation method comprising a process of handing over a mobile terminal that has stopped the compressed mode.

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