WO2012114771A1 - Base station and method for controlling same - Google Patents

Abstract

This base station (10) is capable of wireless communication with a portable communication terminal (20), wherein the base station (10) is provided with: a storage unit (200) for storing a first start timing for the portable communication terminal (20) in a first intermittent reception state of the portable communication terminal (20); and a controller (100) for starting, when the first launch timing is reached in an instance in which the portable communication terminal (20) is not in an intermittent reception state, an assessment as to whether or not the portable communication terminal (20) is in the first intermittent reception state.

Description

Base station and control method thereof Cross-reference to related applications

This application claims priority between Japanese Patent Application No. 2011-39440 (filed on Feb. 25, 2011) and Japanese Patent Application No. 2011-39498 (filed on Feb. 25, 2011). Yes, the entire disclosure of that application is incorporated herein by reference.

The present invention relates to a base station in a mobile communication system and a control method thereof.

Conventionally, mobile communications have been mainly voice calls, and base stations have been widely installed to enable calls in various places. In the meantime, although it is a narrow band, information transmission / reception services such as e-mail have been provided. In a narrow band environment, it takes a considerable amount of time to acquire a large amount of data and software from the network. For this reason, necessary data and software are stored in advance in the storage means of the mobile communication terminal, and read out from the storage means and executed as necessary. The arithmetic processing environment of the mobile communication terminal is low in any case such as a CPU, a memory, and a hard disk as compared with the arithmetic processing environment of the computer and the server. For this reason, the software executed on the mobile communication terminal has been provided with software and functions that can be executed while ensuring comfortable operability even in a low computing environment of the mobile communication terminal.

As a result of the installation of base stations with various output levels in various locations, an environment that can be connected to the network wherever they are now is being prepared. The transmission band in mobile communication is in the direction of further widening by LTE (Long Term Evolution) or WiMAX (Worldwide interoperability for Microwave Access).

The mobile communication terminal operates by supplying power from the built-in battery. For this reason, the operation time of the mobile communication terminal depends on the power capacity of the battery and the power consumption of the mobile communication terminal. In order to realize a long operation time, it is necessary to increase the power capacity of the battery or reduce the power consumption of the terminal itself. However, increasing the power capacity of the battery has the problem of increasing the battery volume and weight. For this reason, reduction of the power consumption of the mobile communication terminal itself is an important issue. As a method for reducing power consumption of the mobile communication terminal itself, there are reduction of power consumption of each component, power supply stop to unused portions such as screen turning off when not in use, and the like. Moreover, in a mobile communication terminal mainly using a call, power consumption is reduced by intermittently receiving a signal from a base station during a standby time instead of always. This technique is called discontinuous reception (DRX).

In intermittent reception control, the mobile communication terminal always supplies power to the communication circuit when it is determined that communication is in progress, and intermittently supplies power to the communication circuit when it is determined that communication has ended. (For example, patent document 1).

This will be explained using LTE as an example. In the intermittent reception control, the mobile communication terminal determines that communication is in progress (communication state) when user packets are transmitted and received. When there is no user packet transmission / reception for a certain period of time, drxInactivityTime (1 to 1260 ms), the mobile communication terminal determines that communication has ended, and transitions to the first intermittent reception state. If no user packet is transmitted / received for a certain period of time drxShortCycleTime (1 to 10240 ms) after entering the first intermittent reception state, the mobile communication terminal transitions to the second intermittent reception state.

In the case of the first intermittent reception state, the mobile communication terminal
T modulo ShortDrxCycle = StartOffset
Power supply to the communication circuit is started at time T, and after a certain time OnDurationTime (1 to 200 ms) has elapsed, the power supply to the communication circuit is stopped. Here, ShortDrxCycle (1 to 640 ms) is an intermittent reception cycle, and StartOffset (<ShortDrxCycle) is a transmission / reception start offset.

In the case of the second intermittent reception state, the mobile communication terminal
T modulo LongDrxCycle = StartOffset
Power supply to the communication circuit is started at time T, and after a certain time OnDurationTime (1 to 200 ms) has elapsed, the power supply to the communication circuit is stopped. Here, LongDrxCycle (10 to 2560 ms) is an intermittent reception cycle, and StartOffset (<LongDrxCycle) is a transmission / reception start offset.

As a result, in the case of the second intermittent reception state, power is supplied to the communication circuit only during the OnDurationTime time out of the LongDrxCycle time. Therefore, it is possible to reduce the power to the communication circuit for (LongDrxCycle-OnDurationTime). It becomes possible.

Note that if the first intermittent reception state is not set, the mobile communication terminal transitions from the communication state to the second intermittent reception state. When receiving an intermittent reception request (DRX Command MAC Control Element) from the base station, the mobile communication terminal transitions from the communication state to the intermittent reception state.

JP 2009-77288 A

However, in the intermittent reception control, when the mobile communication terminal is in a communication state, the mobile communication terminal detects that a user packet is not transmitted or received for a predetermined time drxInactivityTime (1 to 1260 ms) or longer and enters the first intermittent reception state. Transition. For this reason, the mobile communication terminal always keeps measuring the time during which no user packet is transmitted or received. In other words, the mobile communication terminal resets the measured value to 0 if there is user packet transmission / reception, and updates (+1) the measurement value if there is no user packet transmission / reception, and whether or not the drxInactivityTime has reached a certain time. Determine. Similarly, in the first discontinuous reception state, the mobile communication terminal resets the measurement value to 0 if there is user packet transmission / reception, returns to the communication state, and updates the measurement value if there is no user packet transmission / reception. (+1) and determine whether or not the predetermined time drxShortCycleTime (1 to 10240 ms) has been reached.

When the mobile communication terminal is in the intermittent reception state, the base station that is wirelessly connected to the mobile communication terminal needs to perform communication according to the OnDurationTime that can be transmitted and received. For this reason, the intermittent reception control is also performed at the base station in the same manner as the intermittent reception control is performed at the mobile communication terminal, and the state of the mobile communication terminal is monitored.

The mobile communication terminal only needs to grasp the communication state of the terminal itself. On the other hand, the base station needs to grasp the communication state of all mobile communication terminals that are wirelessly connected. For example, if there are 500 terminals to be connected wirelessly, the base station must grasp the communication status of 500 terminals. For this reason, the processing load of the base station by the intermittent reception control is 500 times by simple calculation as compared with the case of one mobile communication terminal. In the case of LTE, a 1 subframe that is a transmission time interval (TTI: Transmission Time Interval) is a very short time of 1 ms. Therefore, performing intermittent reception control for the number of terminals that are wirelessly connected for each TTI has a problem that a large load is imposed on the processing capability of the base station.

Therefore, an object of the present invention made in view of such points is to provide a base station that can reduce the processing load of the base station in intermittent reception control, and a control method therefor.

The invention of the base station according to the first aspect to achieve the above object is
A base station capable of wireless communication with a mobile communication terminal, a storage unit for storing a first start timing to the mobile communication terminal in the first intermittent reception state of the mobile communication terminal;
When the mobile communication terminal is not in the intermittent reception state, the control unit starts determining whether the mobile communication terminal is in the first intermittent reception state at the first start timing. is there.

The invention according to the second aspect is the base station according to the first aspect,
The storage unit further includes a second intermittent reception state of the mobile communication terminal having a second intermittent reception cycle that is longer than a first intermittent reception cycle of the first intermittent reception state. 2 start timing,
When the mobile communication terminal is in the first intermittent reception state, the control unit determines whether the mobile communication terminal is in the second intermittent reception state at the second start timing. It is characterized by starting.

The invention according to a third aspect is the base station according to the first aspect,
The storage unit stores a list in which a plurality of elements in which an expiration time defining the first start timing is associated with the mobile communication terminal are arranged in a short order of the expiration time,
The control unit compares the current time with the expiration time of the element in order from the first element of the list at predetermined time intervals, and corresponds to the element having an expiration time that matches the current time. When the mobile communication terminal is not in the intermittent reception state, the mobile communication terminal starts determining whether the mobile communication terminal is in the first intermittent reception state.
It is characterized by this.

The invention according to a fourth aspect is the base station according to the second aspect,
The storage unit stores a list in which a plurality of elements in which an expiration time that defines the first start timing or the second start timing is associated with the mobile communication terminal are arranged in order of short expiration time. ,
The control unit compares the current time with the expiration time of the element in order from the first element of the list at predetermined time intervals, and corresponds to the element having an expiration time that matches the current time. When the mobile communication terminal is not in the intermittent reception state, the mobile communication terminal starts determining whether or not the mobile communication terminal is in the first intermittent reception state, and the mobile communication terminal is in the first intermittent reception state Starts determining whether or not the mobile communication terminal is in the second intermittent reception state.
It is characterized by this.

The invention according to a fifth aspect is the base station according to the third aspect,
The storage unit further stores a first state monitoring period of each portable communication terminal set to be the same as the first intermittent reception period in the first intermittent reception state of each portable communication terminal,
The control unit calculates a new expiration time for an element having an expiration time that matches the current time at the predetermined time interval based on a first state monitoring period of the mobile communication terminal corresponding to the element. Then, the elements of the list are rearranged so that the elements of the list are arranged in the order of shortest expiration time.

The invention according to a sixth aspect is the base station according to the fourth aspect,
The storage unit further includes a first state monitoring period of each portable communication terminal set to be the same as a first intermittent reception period in the first intermittent reception state of each portable communication terminal, and each portable terminal. Storing the second state monitoring period of each mobile communication terminal set to be the same as the second intermittent reception period in the second intermittent reception state of the communication terminal;
For each element having an expiration time that coincides with the current time for each predetermined time interval, the control unit further determines the number of the mobile communication terminal when the mobile communication terminal corresponding to the element is not in an intermittent reception state. A new expiration time is calculated based on one state monitoring cycle, and if the mobile communication terminal corresponding to the element is in the first intermittent reception state, a new expiration time is calculated based on the second state monitoring cycle of the mobile communication terminal. Expiration time is calculated, and then the elements of the list are rearranged so that the elements of the list are arranged in the order of shortest expiration time.

The invention according to a seventh aspect is the base station according to the fifth aspect,
After calculating the new expiration time, the control unit, based on a cumulative distribution of the existence probabilities of each mobile communication terminal obtained from the first state monitoring period and the number of each mobile communication terminal, It is characterized by determining whether to perform the rearrangement by comparing the expiration time of the element and the new expiration time in order from either the first element or the last element.

The invention according to an eighth aspect is the base station according to the fifth aspect,
After calculating the new expiration time, the control unit, when there are a predetermined number of elements having an expiration time that matches the new expiration time in the list, the same expiration time as the new expiration time The rearrangement is performed by shifting the expiration times of the elements so that the number of elements having a value is less than the predetermined number.

The invention of the control method of the base station according to the ninth aspect to achieve the above object,
A base station control method capable of wireless communication with a mobile communication terminal,
When the mobile communication terminal is not in the intermittent reception state, the mobile communication terminal is in the first intermittent reception state at the first start timing for the mobile communication terminal in the first intermittent reception state of the mobile communication terminal. It is characterized by comprising the step of starting the determination of whether or not there is.

An invention according to a tenth aspect is the base station control method according to the ninth aspect,
When the portable communication terminal is in the first intermittent reception state, the second intermittent reception of the portable communication terminal having a second intermittent reception cycle longer than the first intermittent reception cycle of the first intermittent reception state. A step of starting a determination as to whether or not the mobile communication terminal is in the second discontinuous reception state at a second start timing for the mobile communication terminal in a state. .

An invention according to an eleventh aspect is the base station control method according to the ninth aspect,
For each predetermined time interval, a plurality of elements in which an expiration time defining the first start timing and the mobile communication terminal are associated with each other are arranged in order from the shortest expiration time, in order from the first element in the list. Comparing the time with the expiration time of the element;
As a result of the comparison, for an element having an expiration time that matches the current time, if the mobile communication terminal corresponding to the element is not in the intermittent reception state, whether or not the mobile communication terminal is in the first intermittent reception state The step of starting the determination of
It is characterized by comprising.

The invention according to a twelfth aspect is the base station control method according to the tenth aspect,
For each predetermined time interval, the head of a list in which a plurality of elements in which expiration times defining the first start timing or the second start timing are associated with the mobile communication terminal are arranged in the order of short expiration time Comparing the current time with the expiration time of the element, in order from the element of
As a result of the comparison, for an element having an expiration time that matches the current time, if the mobile communication terminal corresponding to the element is not in the intermittent reception state, whether or not the mobile communication terminal is in the first intermittent reception state Starting the determination, and if the mobile communication terminal is in the first intermittent reception state, starting the determination whether the mobile communication terminal is in the second intermittent reception state;
It is characterized by comprising.

An invention according to a thirteenth aspect is the base station control method according to the eleventh aspect,
As a result of the comparison, for the element having an expiration time that matches the current time, the portable communication terminal set to be the same as the first intermittent reception cycle in the first intermittent reception state of the portable communication terminal corresponding to the element Calculating a new expiration time based on the first state monitoring period of:
Rearranging the elements of the list so that the elements of the list are arranged in the order of shortest expiration time;
It is characterized by comprising.

An invention according to a fourteenth aspect is the base station control method according to the twelfth aspect,
As a result of the comparison, with respect to an element having an expiration time that coincides with the current time, if the mobile communication terminal corresponding to the element is not in the intermittent reception state, the first intermittent in the first intermittent reception state of the mobile communication terminal A new expiration time is calculated based on the first state monitoring cycle of the mobile communication terminal set to be the same as the reception cycle, and when the mobile communication terminal corresponding to the element is in the first intermittent reception state, Calculating a new expiration time based on the second state monitoring period of the mobile communication terminal set to be the same as the second intermittent reception period in the second intermittent reception state of the mobile communication terminal;
Rearranging the elements of the list so that the elements of the list are arranged in the order of shortest expiration time;
It is characterized by comprising.

The invention according to a fifteenth aspect is the base station control method according to the thirteenth aspect,
After calculating the new expiration time, based on the cumulative distribution of the existence probabilities of each mobile communication terminal obtained from the first state monitoring period and the number of each mobile communication terminal, It is characterized by determining whether to perform the rearrangement by comparing the expiration time of the element and the new expiration time in order from any element.

An invention according to a sixteenth aspect is the base station control method according to the thirteenth aspect,
After calculating the new expiration time, the number of elements having the same expiration time as the new expiration time when there are a predetermined number or more of elements having an expiration time that matches the new expiration time in the list The rearrangement is performed by shifting the expiration times of the elements so that the value becomes less than the predetermined number.

According to the present invention, the processing load on the base station in intermittent reception control can be reduced.

It is a block diagram which shows the mobile communication system of Embodiment 1 of this invention. It is a figure for demonstrating the state monitoring timing for the base station 10 of Embodiment 1 of this invention to perform the state monitoring of the specific portable communication terminal 20. FIG. It is a figure for demonstrating the 2nd setting value memorize | stored in the base station of Embodiment 1 of this invention. It is a flowchart which shows the process of the intermittent reception control which the base station in Embodiment 1 of this invention performs at the time of completion of a random access (Random | Access) procedure. It is a flowchart which shows the intermittent reception control process which the base station in Embodiment 1 of this invention performs for every TTI. It is a flowchart which shows the intermittent reception control process which the base station in Embodiment 1 of this invention performs at the time of transmission / reception of a user packet. 7 is a flowchart of intermittent reception control processing performed by the base station in the first embodiment of the present invention in bandwidth allocation. It is a flowchart which shows the process performed when the base station in Embodiment 1 of this invention registers expiration time ExpTim into a DrxTime management table. It is a flowchart which shows the process of the intermittent reception control which the base station in Embodiment 2 of this invention performs at the time of completion of a random access (Random | Access) procedure. It is a flowchart which shows the intermittent reception control process which the base station in Embodiment 2 of this invention performs for every TTI. It is a flowchart which shows the intermittent reception control process which the base station in Embodiment 2 of this invention performs at the time of transmission / reception of a user packet. It is a flowchart of the intermittent reception control process which the base station in Embodiment 2 of this invention performs in band allocation. It is a flowchart which shows the process performed when the base station in Embodiment 2 of this invention registers expiration time ExpTim into a DrxTime management table. It is a graph which shows an example of the relationship between the existence probability p of the portable communication terminal which has three different state monitoring periods c1, c2, and c3, and time t. It is a graph which shows an example of the relationship between the cumulative distribution q of the existence probability of the mobile communication terminal which has three different state monitoring periods c1, c2, and c3, and time t. It is a graph which shows the other example of the relationship between the cumulative distribution q of the existence probability of the mobile communication terminal which has three different state monitoring periods c1, c2, and c3, and time t. It is a flowchart which shows the process performed when the base station in Embodiment 3 of this invention registers expiration time ExpTim into a DrxTime management table. It is a graph which shows the relationship between the density d of the portable communication terminal in the case of FIG. 15, and time t. It is a graph which shows the relationship between the density d of the portable communication terminal in the case of FIG. 16, and time t.

Embodiment 1 FIG.
A first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the present invention is applied to LTE.

FIG. 1 is a block diagram showing the mobile communication system of the first embodiment. The mobile communication system 1 includes a base station 10 and a plurality of mobile communication terminals (UE: User Equipment) 20 capable of wireless communication with the base station 10. The base station 10 includes a control unit 100 including a CPU and a storage unit 200 including a RAM. The storage unit 200 stores a DrxTime management table 201 and a Drx setting value 202, which will be described later, as well as an intermittent reception control program. The control unit 100 performs intermittent reception control by executing an intermittent reception control program stored in the storage unit 200.

FIG. 2 is a diagram for explaining state monitoring timing for the base station 10 of the first embodiment to monitor the state of a specific mobile communication terminal 20. The horizontal axis indicates time. Time T = SFN × 10 + subframe. Here, SFN is a system frame number. When the time T satisfies the following formula (1), the base station 10 determines whether or not to monitor the state of the mobile communication terminal 20, that is, whether or not to perform state transition.
(T-Offset) modulo Cycle = 0 (1)
In Expression (1), Cycle is an intermittent reception cycle in the intermittent reception state after the state transition when it is determined that the state transition is performed. Offset is a transmission / reception start offset from time T = 0 in the intermittent reception state after the state transition when it is determined that state transition is performed, that is, a transmission / reception time (DurTim) start timing in the intermittent reception state.

Next, the Drx setting value 202 stored in the storage unit 200 of the base station 10 will be described. The Drx setting value 202 includes a first setting value 221 that defines the intermittent reception operation of the mobile communication terminal 20 and a second setting value 222 that defines the state monitoring operation of the base station 10.

The first setting value 221 is set according to the service type, QoS class, etc., and more generally may be set for each radio bearer. The first set value 221 is notified to the mobile communication terminal 20 at an arbitrary timing. Thereby, the mobile communication terminal 20 performs state transition appropriately without an instruction from the base station 10. As shown in Table 1 below, the first set value 221 may define a single intermittent reception cycle or may define two different intermittent reception cycles. In the first embodiment, the case where a single intermittent reception cycle is defined is a case where only a set value corresponding to a long intermittent reception cycle is set and a set value corresponding to a short intermittent reception cycle is not set. . The case where two different intermittent reception periods are defined is a case where set values corresponding to a short intermittent reception period and a long intermittent reception period are set.

In Table 1, Cycle is an intermittent reception cycle, and TTI <ShortDrxCycle <LongDrxCycle. DurTim is the transmission / reception time in the intermittent reception state, and TTI ≤ShortOnDurationTime <LongOnDurationTime. Offset is a value that defines the transmission / reception start offset, that is, the start timing of the transmission / reception time DurTim in the intermittent reception state.

FIG. 3 is a diagram for explaining the second set value 222 stored in the base station of the first embodiment. The second setting value 222 is stored in the storage unit 200 in association with each first setting value 221. In FIG. 3, each column of “ShortDRX” is associated with the case where the ShortDRX setting value is included in the first setting value 221 and the case where it is not included. “No ShortDRX setting” means the case where the ShortDRX setting value is not included in the first setting value 221, and “ShortDRX setting” means that the ShortDRX setting value is included in the first setting value 221. Means that Each row of “Drx state” is associated with the state of the mobile communication terminal 20 determined by the base station 10 by state monitoring. “Non” means that communication is being performed substantially continuously (hereinafter referred to as “communication state”), and “Short” is intermittent reception control using the ShortDRX setting value of the first setting value 221. (Long) means that intermittent reception control is being performed using the LongDRX setting value of the first setting value 221 (hereinafter referred to as “first intermittent reception state”). , Referred to as “second discontinuous reception state”).

In FIG. 3, DrxTim is a state monitoring time which is a threshold used for state monitoring. Cycle is a state monitoring cycle. Offset is a value that defines the state monitoring start offset, that is, the start timing of the state monitoring cycle Cycle.

In the column “ShortDRX not set” in FIG. 3, when Drx state = Non, the state monitoring time DrxTim is set to drxInactivityTime. Further, the state monitoring cycle Cycle and the state monitoring start offset Offset are set to the same values as the intermittent reception cycle Cycle and the transmission / reception start offset Offset in the LongDRX setting value of the first setting value 221, respectively.

When Drx state = Long, state monitoring time DrxTim, state monitoring cycle Cycle, and state monitoring start offset Offset are set to the same values as when Drx state = Non.

On the other hand, in the column “ShortDRX is set” in FIG. 3, when Drx state = Non, the state monitoring time DrxTim is set to drxInactivityTime. The state monitoring cycle Cycle and the state monitoring start offset Offset are set to the same values as the intermittent reception cycle Cycle and the transmission / reception start offset Offset in the ShortDRX setting value of the first setting value 221, respectively.

When Drx state = Short, the state monitoring time DrxTim is set to drxInactivityTime + ShortDrxCycle × drxShortCycleTime. Here, since the time during which user packets are not transmitted / received in the intermittent reception state (hereinafter referred to as “no communication time”) is viewed as continuation from the time when Drx state = Non, there is no time when Drx state = Short. DrxInactivityTime is added to the communication time threshold ShortDrxCycle × drxShortCycleTime. Further, the state monitoring cycle Cycle and the state monitoring start offset Offset are set to the same values as the intermittent reception cycle Cycle and the transmission / reception start offset Offset in the LongDRX setting value of the first setting value 221, respectively.

When Drx state = Long, state monitoring time DrxTim, state monitoring cycle Cycle, and state monitoring start offset Offset are set to the same values as when Drx state = Short.

Thus, in the first embodiment, the state monitoring start timing is matched with the transmission / reception start timing in the intermittent reception state after the state transition is made when it is determined that the state transition is performed. That is, the start timing of the state monitoring while Drx state = Non is the same as the start timing of transmission / reception in the Drx state = Short when there is ShortDRX setting, and the start timing of transmission / reception in the Drx state = Long when there is no ShortDRX setting To match. Similarly, the start timing of state monitoring while Drx state = Short is matched with the start timing of transmission / reception when Drx state = Long. However, the start timing of state monitoring while Drx state = Long is matched with the transmission / reception start timing when Drx state = Long.

Next, the DrxTime management table 201 stored in the storage unit 200 of the base station 10 will be described. The DrxTime management table 201 stores a list 211 in which associations (hereinafter referred to as “elements”) 210 of the respective mobile communication terminals 20 and expiration times ExpTim are arranged in the order of short expiration times ExpTim. The expiration time ExpTim is a value that defines the start timing of state monitoring. Accordingly, the base station 10 monitors the status of each mobile communication terminal 20 in order from the mobile communication terminal 20 corresponding to the element 210 at the head of the DrxTime management table 201.

Next, with reference to FIG. 4 to FIG. 8, the process of the intermittent reception control of the base station in the first embodiment will be described. The base station 10 performs state monitoring in the processes of FIGS. 4 to 6 to calculate a new expiration time ExpTim, and then each expiration time ExpTim registered in the DrxTime management table 201 in the process of FIG. The elements 210 are rearranged so that they are arranged in a short order.

FIG. 4 is a flowchart showing the intermittent reception control process performed by the base station in the first embodiment when the random access (Random Access) procedure is completed. After the base station 10 performs random access to the specific mobile communication terminal 20, the control unit 100 registers the mobile communication terminal 20 in the DrxTime management table 201 or sets the Drx setting value 202. It is determined whether or not there is (step S10). If it is determined in S10 that registration or setting has not been performed (S10, Yes), the process ends.

On the other hand, when determining that registration or setting is performed in S10 (S10, No), the control unit 100 determines whether or not the mobile communication terminal 20 is in the Drx state = Long (step S11). When the Drx state is Long (S11, Yes), the element 210 corresponding to the mobile communication terminal 20 is cut out from the Long state list 211 of the DrxTime management table 201 (Step S12), and the process proceeds to S13. By S12, the base station 10 removes the mobile communication terminal 20 from the state monitoring target until it detects transmission / reception of a user packet with the mobile communication terminal 20. Therefore, the processing load on the base station 10 is reduced. On the other hand, if it is determined in S11 that the Drx state is not Long (S11, No), the process directly proceeds to S13.

In S13, the control unit 100 sets the portable communication terminal 20 to the Drx state = Non, and sets the oldest transmission time TimSndLst representing the time when data was last transmitted from the base station 10 to the portable communication terminal 20 to the current time CurTim. Set (step S13). Next, the control unit 100 determines whether or not the first setting value 221 of the Drx setting value 202 includes the ShortDRX setting value for the mobile communication terminal 20 (step S14). If it is determined in S14 that the first setting value 221 does not include the ShortDRX setting value (S14, No), the second setting value 222 is placed in the “ShortDRX not set” column and the “Non” row in FIG. The corresponding value is set (step S15), and the process proceeds to S17. On the other hand, if it is determined in S14 that the first setting value 221 includes the ShortDRX setting value (S14, Yes), the second setting value 222 is displayed in the “ShortDRX setting” column and the “Non” row in FIG. (Step S16), and the process proceeds to S17.

In S17, the control unit 100 determines whether or not the current time CurTim is greater than or equal to the state monitoring start offset Offset (step S17). When it is determined in S17 that the current time CurTim is less than the state monitoring start offset Offset (S17, No), the expiration time ExpTim of the next state monitoring is set to
ExpTim = Offset
(Step S18), the calculated expiration time ExpTim is registered in the DrxTime management table 201 (step S20), and the process ends.

On the other hand, if it is determined in S17 that the current time CurTim is equal to or greater than the state monitoring start offset Offset (S17, Yes), the expiration time ExpTim of the next state monitoring is set to
Pwr = (INT) (CurTim / Cycle)
ExpTim = Cycle × (Pwr + 1) + Offset
(Step S19), the calculated expiration time ExpTim is registered in the DrxTime management table 201 (step S20), and the process ends.

4, since the state is monitored every period longer than TTI, the processing load on the base station can be reduced.

FIG. 5 is a flowchart showing an intermittent reception control process performed by the base station in the first embodiment for each TTI. The control unit 100 reads the expiration time ExpTim of the element 210 at the head of the list 211 of the DrxTime management table 201 (step S40), and determines whether or not the current time CurTim has reached the expiration time ExpTim (step S41). If it is determined in S41 that the current time CurTim has not reached the expiration time ExpTim (S41, Yes), the control unit 100 ends the process without doing anything for the other elements 210 registered in the DrxTime management table 201. Thereby, it can be ensured that state monitoring is not performed until the state monitoring start timing is reached, and the processing load on the base station 10 can be reduced.

On the other hand, if it is determined in S41 that the current time CurTim has reached the expiration time ExpTim (S41, No), it is determined whether or not the mobile communication terminal 20 corresponding to this element 210 is in the Drx state = Long (step) S42). If it is determined in S42 that the Drx state = Long (S42, Yes), this element is moved from the currently used list to the Long state list (step S57). After S57, if the number of times of returning to S40 has not reached the number of elements 210 registered in the DrxTime management table 201, the process returns to S40. On the other hand, after S57, when the number of times of returning to S40 has reached the number of elements 210 registered in the DrxTime management table 201, the process ends.

On the other hand, if it is determined in S42 that the Drx state is not Long (S42, No), the no-communication time TimNon is set to TimNon = CurTim-TimLstSnd
(Step S43). Here, TimLstSnd is the oldest transmission time, that is, the time at which data was last transmitted from the base station 10 to the mobile communication terminal 20.

Next, the control unit 100 determines whether the no-communication time TimNon is equal to or longer than the state monitoring time DrxTim (step S44). If it is determined in S44 that the no-communication time TimNon is less than the state monitoring time DrxTim (No in S44), the control unit 100 sets ExpTim = ExpTim + Cycle to the next state monitoring expiration time ExpTim.
(Step S45), and the calculated expiration time ExpTim is registered in the DrxTime management table 201 (step S53). After S53, if the number of times of returning to S40 has not reached the number of elements 210 registered in the DrxTime management table, the process returns to S40. On the other hand, if the number of times of returning to S40 after S53 has reached the number of elements 210 registered in the DrxTime management table, the process is terminated.

On the other hand, when it is determined in S44 that the no-communication time TimNon is equal to or longer than the state monitoring time DrxTim (Yes in S44), the control unit 100 determines whether or not the mobile communication terminal 20 is in the Drx state = Short or It is determined whether or not the first setting value 221 of the communication terminal 20 includes a ShortDRX setting value (step S46). When it is determined in S46 that the mobile communication terminal 20 is not in the Drx state = Short, or the first setting value 221 includes the ShortDRX setting value (S46, No), the base station 10 makes an intermittent reception request to the mobile communication terminal 20 (DRX Command MAC Control Element) is transmitted (step S47). Next, the control unit 100 sets the second setting value 222 of the Drx setting value 202 to a value corresponding to the “ShortDRX setting” column and the “Short” row in FIG. 3 (step S48). The state of the communication terminal 20 is changed to Drx state = Short (step S49).

Next, the control unit 100 determines whether or not the current time CurTim is greater than or equal to the state monitoring start offset Offset (step S50). If it is determined in S50 that the current time CurTim is less than the state monitoring start offset Offset (S50, No), the expiration time ExpTim of the next state monitoring is set to
ExpTim = Offset
(Step S51), and the calculated expiration time ExpTim is registered in the DrxTime management table 201 (step S53). After S53, if the number of times of returning to S40 has not reached the number of elements 210 registered in the DrxTime management table, the process returns to S40. On the other hand, if the number of times of returning to S40 after S53 has reached the number of elements 210 registered in the DrxTime management table, the process is terminated.

On the other hand, if it is determined in S50 that the current time CurTim is equal to or greater than the state monitoring start offset Offset (S50, Yes), the expiration time ExpTim of the next state monitoring is set to
Pwr = (INT) (CurTim / Cycle)
ExpTim = Cycle × (Pwr + 1) + Offset
(Step S52), and the calculated expiration time ExpTim is registered in the DrxTime management table 201 (step S53). After S53, if the number of times of returning to S40 has not reached the number of elements 210 registered in the DrxTime management table, the process returns to S40. On the other hand, if the number of times of returning to S40 after S53 has reached the number of elements 210 registered in the DrxTime management table, the process is terminated.

When it is determined in S46 that the mobile communication terminal 20 is in the Drx state = Short, or the first setting value 221 does not include the ShortDRX setting value (S46, Yes), the control unit 100 then makes this mobile communication terminal 20 Is in the Drx state = Non (step S54). If it is determined in S54 that the mobile communication terminal 20 is not in the Drx state = Non (S54, No), the process proceeds to S56. On the other hand, if it is determined in S54 that the Drx state = Non (S54, Yes), the base station 10 transmits an intermittent reception request (DRX Command MAC Control Element) to the mobile communication terminal 20 (step S55), and then to S56 move on.

In S56, the control unit 100 changes the state of the mobile communication terminal 20 to the Drx state = Long (S56), and moves this element 210 from the currently used state list 211 to the Long state list (Step S57). After S57, if the number of times of returning to S40 has not reached the number of elements 210 registered in the DrxTime management table 201, the process returns to S40. On the other hand, if the number of times of returning to S40 after S57 has reached the number of elements 210 registered in the DrxTime management table 201, the processing is terminated.

The processing load of the base station for each TTI can be reduced by the processing of FIG.

FIG. 6 is a flowchart showing an intermittent reception control process performed by the base station in the first embodiment when transmitting and receiving user packets. After the base station 10 transmits / receives a user packet to / from a specific mobile communication terminal 20, the control unit 100 determines whether or not the Drx setting value 202 is set for the mobile communication terminal 20 ( Step S70). If it is determined in S70 that the setting has not been made (S70, Yes), the process ends.

On the other hand, when it is determined in S70 that the Drx set value 202 has been set (S70, No), the control unit 100 sets the oldest transmission time TimSndLst to the current time CurTim (step S71), and this mobile communication It is determined whether or not the terminal 20 is in the Drx state = Non (step S72). If it is determined in S72 that the Drx state = Non, the mobile communication terminal 20 is set to the Drx state = Non (step S81), and the process is terminated.

On the other hand, when it is determined in S72 that the mobile communication terminal 20 is not in the Drx state = Non, the control unit 100 determines whether the mobile communication terminal 20 is in the Drx state = Long (step S73). When it is determined in S73 that the Drx state is not Long (S73, No), the process proceeds to S75. On the other hand, if it is determined in S73 that the Drx state is Long (S73, Yes), the element 210 corresponding to the mobile communication terminal 20 is cut out from the Long state list of the DrxTime management table 201 (Step S74), and then, in S75. move on.

In S75, the control unit 100 determines whether or not the first setting value 221 of the Drx setting value 202 includes the ShortDRX setting value for the communication portable terminal 20 (step S75). If it is determined in S75 that the ShortDRX set value is not included (S75, No), the Drx state is set to Non (step S81), and the process is terminated.

On the other hand, when it is determined in S75 that the first setting value 221 includes the ShortDRX setting value (S75, Yes), the control unit 100 sets the second setting value 222 of the Drx setting value 202 to “ShortDRX setting exists” in FIG. ”Column and“ Non ”row (step S76), and it is determined whether or not the current time CurTim is equal to or greater than the state monitoring start offset Offset (step S77). When it is determined in S77 that the current time CurTim is less than the state monitoring start offset Offset (S77, No), the control unit 100 sets an expiration time ExpTim for the next state monitoring,
ExpTim = Offset
(Step S78), and the calculated expiration time ExpTim is registered in the DrxTime management table 201 (step S80). After S80, the control unit 100 makes a state transition to Drx state = Non (step S81), and thereafter ends the process.

On the other hand, if it is determined in S77 that the current time CurTim is equal to or greater than the state monitoring start offset Offset (S77, Yes), the expiration time ExpTim of the next state monitoring is set to
Pwr = (INT) (CurTim / Cycle)
ExpTim = Cycle × (Pwr + 1) + Offset
(Step S79), and the calculated expiration time ExpTim is registered in the DrxTime management table 201 (step S80). After S80, the control unit 100 makes a state transition to Drx state = Non (step S81), and thereafter ends the process.

Since the state monitoring is performed every cycle longer than TTI by the processing of FIG. 6, the processing load on the base station can be reduced.

FIG. 7 is a flowchart of the intermittent reception control process performed by the base station in the first embodiment in band allocation. When a call is generated from a specific mobile communication terminal 20, the control unit 100 determines whether or not the Drx setting value 202 has been set for the mobile communication terminal 20 (step S100). If it is determined in S100 that the Drx set value 202 has not been set (S100, Yes), the process ends.

On the other hand, when it is determined in S100 that the Drx set value 202 is set (S100, No), the control unit 100 determines whether or not the mobile communication terminal 20 is in the Drx state = Non (step S100). S101). If it is determined in S101 that the Drx state is not Non (S101, No), then the control unit 100 determines whether or not the mobile communication terminal 20 is in the Drx state = Short (Step S102). When it is determined in S102 that the Drx state is not Short (S102, No), the mobile communication terminal 20 is in the Drx state = Long. Next, the control unit 100 sets the state monitoring cycle Cycle and the state monitoring start offset Offset to LongDrxCycle and drxStartOffset, respectively (step S103), and proceeds to S106.

On the other hand, when it is determined in S102 that the Drx state is Short (S102, Yes), the control unit 100 determines whether the no-communication time TimNon is equal to or longer than the state monitoring time DrxTim (Step S104). If it is determined in S104 that the no-communication time TimNon is equal to or longer than the state monitoring time DrxTim (Yes in S104), the control unit 100 does not request the bandwidth allocation from the scheduler (Step S110) and ends the process. On the other hand, when it is determined in S104 that the no-communication time TimNon is less than the state monitoring time DrxTim (S104, No), the control unit 100 sets the state monitoring cycle Cycle and the state monitoring start offset Offset to ShortDrxCycle and drxStartOffset% ShortDrxCycle, respectively. (Step S105), the process proceeds to S106.

In S106, the elapsed time TimJdg from the state monitoring start timing in the current state monitoring cycle Cycle is set to TimJdg = (CurTim-Offset)% Cycle
(Step S106). Next, the control unit 100 determines whether or not this elapsed time TimJdg is less than the transmission / reception time DurTim in the intermittent reception state (step S107). In S107, the control unit 100 determines whether or not the mobile communication terminal 20 is in the transmission / reception time in the intermittent reception state. When it is determined in S107 that the elapsed time TimJdg is equal to or longer than the transmission / reception time DurTim (No in S107), the control unit 100 does not request the scheduler to allocate a band (step S110) and ends the process. On the other hand, if it is determined in S107 that the elapsed time TimJdg is less than the transmission / reception time DurTim (S107, Yes), the process proceeds to S111.

When it is determined in S101 that the mobile communication terminal 20 is in the Drx state = Non (S101, Yes), the control unit 100 sets the no-communication time TimNon as
TimNon = CurTim-TimLstSnd
(Step S108), it is determined whether or not the no-communication time TimNon is equal to or longer than the state monitoring time DrxTim (step S109). If it is determined in S109 that the no-communication time TimNon is equal to or longer than the state monitoring time DrxTim (S109, Yes), the control unit 100 does not request the scheduler to allocate a bandwidth (step S110) and ends the process. On the other hand, when it is determined in S109 that the no-communication time TimNon is less than the state monitoring time DrmTim (S109, No), the process proceeds to S111.

In S111, the control unit 100 determines whether or not synchronization is established with the mobile communication terminal 20 (step S111), and if it is determined that synchronization is established (S111, No), band allocation to the scheduler Is requested (step S112), and the process is terminated.

On the other hand, if it is determined in S111 that the synchronization has not been established (S111, Yes), the scheduler is requested to establish synchronization (Format1A) with the mobile communication terminal 20 (step S113), and a bandwidth allocation request is made to the scheduler. Without processing (step S114), the process ends.

FIG. 8 is a flowchart showing processing performed when the base station in the first embodiment registers the expiration time ExpTim in the DrxTime management table. The process of FIG. 8 corresponds to the process of registering the expiration time ExpTim newly calculated in FIGS. 4 to 6 in the DrxTime management table. First, when a new expiration time ExpTim is calculated, the control unit 100 determines whether or not the number of elements 210 registered in the currently used state list 211 of the DrxTime management table 201 is 0 (step S130). When it is determined in S130 that the number of registrations is 0 (S130, Yes), the element 210 (hereinafter referred to as “designated element”) corresponding to the calculated expiration time ExpTim is stored in the currently used state list 211. It arrange | positions at the tail (namely, head) (step S145), and complete | finishes a process.

On the other hand, when it is determined in S130 that the number of registered elements 210 in the currently used state list 211 for this mobile communication terminal 20 is not zero (S130, No), the control unit 100 then expires the designated element 210. ExpTim (A) is read (step S131). Next, the control unit 100 sets the comparison element 210 as the last pointer of the currently used state list 211 (step S132), and reads the expiration time ExpTim (i) of the comparison element 210 (step S133). Next, the control unit 100 determines whether or not the expiration time ExpTim (A) of the designated element 210 matches the expiration time ExpTim (i) of the comparison element 210 (step S134). If it is determined in S134 that they do not match (S134, No), it is next determined whether or not the expiration time ExpTim (A) of the designated element 210 is longer than the expiration time ExpTim (i) of the comparison element 210 (step S135). . If it is determined in S135 that the expiry time ExpTim (A) of the designated element 210 is shorter than the expiry time ExpTim (i) of the comparison element 210 (S135, No), the comparison element 210 is set to the previous element 210 ( Step S136). After S136, if the number of times of returning to S133 has not reached the registered number of the element 210, the process returns to S133. On the other hand, after S136, when the number of times of returning to S133 has reached the number of elements 210 registered in the DrxTime management table 201, the designated element 210 is placed at the top of the currently used state list 211 (step S137). ), The process is terminated. On the other hand, if it is determined in S135 that the expiration time ExpTim (A) of the designated element 210 is longer than the expiration time ExpTim (i) of the comparison element 210 (S135, Yes), the designated element 210 is placed next to the comparison element 210. (Step S138), the process ends.

When it is determined in S134 that the expiration time ExpTim (A) of the designated element 210 matches the expiration time ExpTim (i) of the comparison element 210 (S134, Yes), the control unit 100 next transmits the remaining transmission / reception time of the comparison element 210. RstTim (i)
RstTim (i) = DurTim (i)-ShiftTim (i)
(Step S139). Here, the remaining transmission / reception time RstTim means the time length from the state monitoring start timing to the transmission / reception time end timing. DurTim (i) is the transmission / reception time DurTim at the first set value 221 of the comparison element 210, ShiftTim (i) is the amount of movement of the expiration time ExpTim (i) of the comparison element 210, and the initial value is zero.

Next, the control unit 100 determines whether or not the remaining transmission / reception time RstTim (i) of the comparison element 210 is longer than the transmission / reception time DurTim (A) of the designation element 210 (step S140).

When it is determined in S140 that the remaining transmission / reception time RstTim (i) of the comparison element 210 is equal to or less than the transmission / reception time DurTim (A) of the designated element 210 (S140, No), the control unit 100 sets the movement amount ShiftTim (A) of the designated element 210. Update (+1) (step S141), place the designated element 210 next to the comparison element 210 (step S142), and terminate the process. Thereby, the expiration time ExpTim (A) of the designated element 210 becomes longer than the expiration time ExpTim (i) of the comparison element 210.

On the other hand, when it is determined in S140 that the remaining transmission / reception time RstTim (i) of the comparison element 210 is longer than the transmission / reception time DurTim (A) of the designated element 210 (S140, Yes), the control unit 100 moves the shift amount ShiftTim ( i) is updated (+1) (step S143), the designated element 210 is placed before the comparison element 210 (step S144), and the process is terminated. Thereby, the expiration time ExpTim (i) of the comparison element 210 becomes longer than the expiration time ExpTim (A) of the designated element 210.

That is, in the first embodiment, in principle, each element 210 in the list 211 of the DrxTime management table 201 is stored in a state in which the expiration times ExpTim are arranged in ascending order. However, when there are a plurality of elements 210 having the same expiration time ExpTim, these are arranged in the order of the short remaining transmission / reception time RstTim. Thereby, the number of the mobile communication terminals 20 that perform the state monitoring process for each TTI can be reduced, and the processing load on the base station 10 can be reduced.

Note that when the expiration time ExpTim is shifted from the initial setting time, the control unit 100 retains the movement amount ShiftTim, and at the time of calculating the expiration time ExpTim of the next state monitoring,
ExpTim = ExpTim + Cycle-ShiftTim
To correct. Thereby, the expiration time ExpTim of the next state monitoring is matched with the transmission / reception start timing in the intermittent reception state.

As described above, in the first embodiment, the state monitoring start timing is matched with the transmission / reception start timing in the discontinuous reception state after the state transition when it is determined that the state transition is performed. That is, when the first intermittent reception state is set, the state monitoring start timing during the communication state is set according to the transmission / reception start timing in the first intermittent reception state. If not, the transmission / reception start timing in the second intermittent reception state is set. Similarly, the state monitoring start timing during the first intermittent reception state is matched with the transmission / reception start timing in the second intermittent reception state. However, the start timing of state monitoring while in the second intermittent reception state is matched with the transmission / reception start timing in the second intermittent reception state. As a result, since the state is monitored every period longer than TTI, the processing load on the base station can be reduced.

Also, in the first embodiment, when the base station monitors the state of a plurality of mobile communication terminals, the mobile communication terminals are ordered in the order in which the start timing (ExpTim) of the state monitoring approaches. Then, for each TTI, it is determined whether the current time has reached the start timing of state monitoring in order from the top mobile communication terminal, and only the mobile communication terminal that has reached the start timing of state monitoring is monitored. No processing is performed on the mobile communication terminal. Thereby, the number of portable communication terminals that perform state monitoring processing for each TTI can be reduced, and the processing load on the base station can be reduced.

However, if the updated start timing overlaps with the start timing of another mobile communication terminal when updating the start timing of the state monitor for the mobile communication terminal that has performed state monitoring, Then, the time length (RstTim) from the start timing of the state monitoring to the end timing of the transmission / reception time is compared. Then, for the mobile communication terminal having a longer time from the state monitoring start timing to the transmission / reception time end timing, the state monitoring start timing is delayed and the mobile communication terminal is ordered after the other mobile communication terminal. Thereby, the number of portable communication terminals that perform state monitoring processing for each TTI can be further reduced.

In the present embodiment, the case where the transmission time interval (TTI) is implemented in LTE has been described. However, the present invention is not limited to the implementation in LTE and the transmission time interval. Any time interval may be used.

Embodiment 2. FIG.
In the first embodiment described above, when updating the start timing of state monitoring for the mobile communication terminal that has performed state monitoring, the transmission / reception time ends from the state monitoring timing when it overlaps with the start timing of other mobile communication terminals. Based on the time until the timing, the start timing of one of the mobile communication terminals is shifted later. Thereby, the state monitoring start timing of both terminals can be made different. However, even after the start timings of both terminals are made different in this way, the state monitoring start timing of the mobile communication terminal related to the update may overlap with the start timing of another mobile communication terminal.

Therefore, in the second embodiment, by further reducing the number of portable communication terminals having the same state monitoring start timing, the number of portable communication terminals that perform state monitoring processing for each TTI is further reduced. The processing load is further reduced.

With reference to FIG. 9 to FIG. 13, the process of the intermittent reception control of the base station in the second embodiment will be described. The description will focus on the differences from the first embodiment. The matters described with reference to FIGS. 1 to 3 are also applied to the second embodiment. The base station 10 performs state monitoring by the processes of FIGS. 9 to 11 to calculate a new expiration time ExpTim, and then, in the process of FIG. 13, each element 210 of the DrxTime management table 201 is in the order of the shortest expiration time ExpTim. Rearrange the elements so that they line up.

FIG. 9 is a flowchart showing the intermittent reception control process performed by the base station in the second embodiment when the random access (Random Access) procedure is completed. Steps S150 to S160 correspond to steps S10 to S20 in FIG. 4, respectively. Steps S155 and S156 differ from steps S15 and S16 in FIG. 4 in that the movement amount ShiftTim of the expiration time ExpTim is set to zero.

In step S158, the expiration time ExpTim of the next state monitoring is set to
ExpTim = Offset + ShiftTim
4 is different from step S18 in FIG.

In step S159, the next expiration time ExpTim is set to
Pwr = (INT) (CurTim / Cycle)
ExpTim = Cycle × (Pwr + 1) + Offset + ShiftTim
4 is different from step S19 in FIG.

Other processing is the same as the processing in FIG.

FIG. 10 is a flowchart showing intermittent reception control processing performed by the base station in the second embodiment for each TTI. Steps S180 to S197 correspond to steps S40 to S57 in FIG. 5, respectively. Step S188 differs from step S48 in FIG. 5 in that the movement amount ShiftTim of the expiration time ExpTim is set to zero.

In step S191, the expiration time ExpTim of the next state monitoring is set to
ExpTim = Offset + ShiftTim
Is different from step S51 in FIG.

In step S192, the next expiration time ExpTim is set to
Pwr = (INT) (CurTim / Cycle)
ExpTim = Cycle × (Pwr + 1) + Offset + ShiftTim
Is different from step S52 in FIG.

Other processing is the same as the processing in FIG.

FIG. 11 is a flowchart showing an intermittent reception control process performed by the base station in the second embodiment when transmitting and receiving user packets. Steps S210 to S221 correspond to steps S70 to S81 in FIG. 6, respectively. Step S216 differs from step S76 in FIG. 6 in that the shift amount ShiftTim of the expiration time ExpTim is set to zero.

In step S218, the expiration time ExpTim of the next state monitoring is
ExpTim = Offset + ShiftTim
Is different from step S78 in FIG.

In step S219, the next expiration time ExpTim is set to
Pwr = (INT) (CurTim / Cycle)
ExpTim = Cycle × (Pwr + 1) + Offset + ShiftTim
Is different from step S79 in FIG.

Other processing is the same as the processing in FIG.

FIG. 12 is a flowchart of the intermittent reception control process performed by the base station in the second embodiment in bandwidth allocation. Steps S240 to S254 correspond to steps S100 to S114 in FIG. 7, respectively. Steps S243 and S245 differ from Steps S103 and S105 in FIG. 7 in that the movement amount ShiftTim of the expiration time ExpTim is set to 0.

Other processing is the same as the processing in FIG.

FIG. 13 is a flowchart showing processing performed when the base station in the second embodiment registers the expiration time ExpTim in the DrxTime management table. The process of FIG. 13 corresponds to the process of registering the expiration time ExpTim newly calculated in FIGS. 9 to 11 in the DrxTime management table. First, when a new expiration time ExpTim is calculated, the control unit 100 determines whether or not the number of elements 210 registered in the currently used state list 211 of the DrxTime management table 201 is 0 (step S270). If it is determined in S270 that the number of registrations is 0 (Yes in S270), the element (hereinafter referred to as “designated element”) 210 corresponding to the calculated expiration time ExpTim is included in the currently used state list 211. It arrange | positions at the tail (namely, head) (step S286), and complete | finishes a process.

On the other hand, if it is determined in S270 that the number of registered elements 210 in the currently used state list 211 for this mobile communication terminal 20 is not zero (No in S270), the control unit 100 then tries to newly register. The expiration time ExpTim (A) of the designated element 210 to be read is read (step S271). Next, the control unit 100 sets the comparison element 210 as the last pointer of the currently used state list 211 (step S272), and reads the expiration time ExpTim (i) of the comparison element 210 (step S273). Next, the control unit 100 determines whether or not the expiration time ExpTim (A) of the designated element 210 matches the expiration time ExpTim (i) of the comparison element 210 (step S274). If it is determined in S274 that they do not match (No in step S274), it is next determined whether or not the expiration time ExpTim (A) of the designated element 210 is longer than the expiration time ExpTim (i) of the comparison element 210 (step S275). ). If it is determined in S275 that the expiry time ExpTim (A) of the designated element 210 is shorter than the expiry time ExpTim (i) of the comparison element 210 (No in step S275), the comparison element is set to the previous element 210 ( Step S276). After S276, if the number of times of returning to S273 has not reached the number of registered elements 210, the process returns to S273. On the other hand, if the number of times of returning to S273 after S276 has reached the number of elements 210 registered in the DrxTime management table 201, the designated element 210 is placed at the top of the currently used state list 211 (step S277). ), The process is terminated. On the other hand, if it is determined in S275 that the expiry time ExpTim (A) of the designated element 210 is longer than the expiry time ExpTim (i) of the comparison element 210 (S275, Yes), the designated element 210 is placed next to the comparison element 210. (Step S278), the process ends.

If it is determined in S274 that the expiry time ExpTim (A) of the designated element 210 matches the expiry time ExpTim (i) of the comparison element 210 (S274, Yes), the control unit 100 then performs the remaining transmission / reception time of the comparison element 210. RstTim (i)
RstTim (i) = DurTim (i)-ShiftTim (i)
(Step S279). Here, the remaining transmission / reception time RstTim means the time length from the state monitoring start timing to the transmission / reception time end timing. DurTim (i) is the transmission / reception time DurTim at the first set value 221 of the comparison element 210, ShiftTim (i) is the amount of movement of the expiration time ExpTim (i) of the comparison element 210, and the initial value is zero.

Next, the control unit 100 determines whether or not the remaining transmission / reception time RstTim (i) of the comparison element 210 is longer than the transmission / reception time DurTim (A) of the designation element 210 (step S280).

When it is determined in S280 that the remaining transmission / reception time RstTim (i) of the comparison element 210 is shorter than the transmission / reception time DurTim (A) of the designated element 210 (S280, No), the control unit 100 moves the shift amount ShiftTim (A) of the designation element 210. Is updated (+1) (step S281), and the designated element 210 is placed next to the comparison element 210 (step S282). Thereby, the expiration time ExpTim (A) of the designated element 210 becomes longer than the expiration time ExpTim (i) of the comparison element 210.

After S282, the comparison element 210 is set to the previous element 210 (step S276). After S276, if the number of times of returning to S273 has not reached the number of registered elements 210, the process returns to S273. Thereby, the control unit 100 determines whether the expiration time ExpTim (A) of the designated element 210 updated in step S282 overlaps the expiration time ExpTim (i) of the comparison element 210 newly set in step S276. Make a comparison and make them different if they overlap. On the other hand, if the number of times of returning to S273 after S276 has reached the number of elements 210 registered in the in-use state list 211 in the DrxTime management table 201, the state list 211 that currently uses the specified element 210. (Step S277), and the process ends.

When it is determined in S280 that the remaining transmission / reception time RstTim (i) of the comparison element 210 is longer than the transmission / reception time DurTim (A) of the specified element 210 (S280, Yes), the control unit 100 moves the shift amount ShiftTim (i) of the comparison element 210. Is updated (+1) (step S283), and the designated element 210 is placed before the comparison element 210 (step S284). Thereby, the expiration time ExpTim (i) of the comparison element 210 becomes longer than the expiration time ExpTim (A) of the designated element 210.

After S284, the comparison element 210 is set to the previous element 210, that is, the designated element 210 (step S285). Next, the comparison element 210 is further set to the element 210 immediately before, that is, the element 210 immediately preceding the designated element 210 (step S276). After S276, if the number of times of returning to S273 has not reached the number of registered elements 210, the process returns to S273. Thereby, the control unit 100 compares the expiration time ExpTim (A) of the designated element 210 with the expiration time ExpTim (i) of the comparison element 210 newly set in step S276, and compares them. If so, make them different. On the other hand, if the number of times of returning to S273 after S276 has reached the number of elements 210 registered in the in-use state list 211 in the DrxTime management table 201, the state list 211 that currently uses the specified element 210. (Step S277), and the process ends.

Note that when the expiration time ExpTim is shifted from the initial set time, the control unit 100 holds the movement amount ShiftTim, and at the time of calculating the next expiration time ExpTim,
ExpTim = ExpTim + Cycle
To calculate ExpTim. That is, unlike the first embodiment, since the correction based on the movement amount ShiftTim is not performed, the next expiration time ExpTim is shifted by the movement amount ShiftTim from the transmission / reception start timing in the intermittent reception state. Thereby, it is possible to reduce the possibility that a plurality of portable communication terminals 20 whose states are monitored by the same state monitoring cycle Cycle are repeatedly monitored at the same timing.

If the shift amount ShiftTim is equal to the transmission / reception time DurTim in the intermittent reception state, when calculating the next expiration time ExpTim,
ExpTim = ExpTim + Cycle-ShiftTim
ShiftTim = 0
Return the movement amount ShiftTim to 0.

As described above, in the second embodiment, when updating the start timing of state monitoring for the mobile communication terminal that performed state monitoring, the update start timing overlaps with the start timing of other mobile communication terminals. The start timings of both terminals are made different as in the first mode. Thereafter, the state monitoring start timing of the mobile communication terminal related to the update is further compared with the start timing of other mobile communication terminals, and if they match, the two are made different. Thereby, the number of portable communication terminals that perform state monitoring processing for each TTI can be further reduced.

In the present embodiment, the case where the transmission time interval (TTI) is implemented in LTE has been described. However, the present invention is not limited to the implementation in LTE and the transmission time interval. Any time interval may be used.

Embodiment 3 FIG.
In the second embodiment described above, in the process of registering the newly calculated expiration time ExpTim in the DrxTime management table 201 (FIG. 13), the expiration time ExpTim (A) of the designated element 210 and the expiration time ExpTim (i) of the comparison element 210. The comparison element 210 is always set in order from the last element 210 of the DrxTime management table 201 toward the top. However, if the designated element 210 is to be placed at the top of the DrxTime management table 201, this designated element 210 performs comparison and rearrangement with all the elements 210 already registered in the DrxTime management table 201. It will be registered after. In such a case, the processing load on the base station 10 is high.

Therefore, the third embodiment predicts whether the designation element 210 should be placed in the first half or the second half of the DrxTime management table 201, and based on the prediction result, the beginning or end of the DrxTime management table 201 It is determined which element 210 of the tail is to be compared and rearranged in order. As a result, the number of comparisons and rearrangements is reduced, and the processing load on the base station 10 is further reduced.

Embodiment 3 of the present invention will be described with reference to FIGS. The description will focus on the differences from the first or second embodiment. The matters described with reference to FIGS. 1 to 3 and 9 to 12 are also applied to the third embodiment.

First, with reference to FIG. 14 to FIG. 16, a method for determining whether to perform comparison and rearrangement in order from the first or last element 210 of the DrxTime management table 201 will be described. FIG. 14 is a graph showing an example of the relationship between the existence probability p of the mobile communication terminals X, Y, and Z having three different state monitoring periods c1, c2, and c3 and the time t. In FIG. 14, the horizontal axis is time t and the vertical axis when there are the same number of mobile communication terminals X, Y, and Z, respectively, and each has state monitoring cycles c1, c2, and c3 (c1 <c2 <c3). Is a graph in which the existence probability p of the mobile communication terminals X, Y, and Z is represented. Since the state monitoring cycle c1 of the mobile communication terminal X is the shortest, the probability that the mobile communication terminal X exists at the arbitrary time within the period [0, c1] is the highest. Similarly, since the state monitoring cycle of the mobile communication terminal Z is the longest, the probability that the mobile communication terminal Z exists at the arbitrary time in the period [0, c3] is the lowest.

FIG. 15 is a graph showing an example of the relationship between the cumulative distribution q of the existence probabilities of mobile communication terminals X, Y, and Z having three different state monitoring periods c1, c2, and c3 and time t. FIG. 16 is a graph showing another example of the relationship between the cumulative distribution q of the existence probabilities of the mobile communication terminals X, Y, and Z having three different state monitoring periods c1, c2, and c3 and the time t. 15 and FIG. 16 have different numbers of mobile communication terminals X, Y, and Z.

In the case of FIG. 15, the time t50 for the cumulative distribution of 50% satisfies t50 <c1. Therefore, it is predicted that 50% of all elements 210 of the DrxTime management table 201 satisfy the expiration time ExpTim <c1. Therefore, when the newly calculated expiration time ExpTim is registered in the DrxTime management table 201, even if the expiration time ExpTim corresponds to any mobile communication terminal X, Y, Z, according to the process of FIG. The expiration times ExpTim are compared and rearranged in order from the last element 210 of the DrxTime management table 201 to the top. As a result, the number of comparisons and rearrangements can be reduced as compared with the case where the expiration times ExpTim are compared and rearranged in order from the first element 210 of the DrxTime management table 201.

On the other hand, in the case of FIG. 16, the time t50 for the cumulative distribution of 50% satisfies c1 <t50 <c2. Therefore, it is predicted that 50% of all elements 210 of the DrxTime management table 201 satisfy the expiration time ExpTim <c2. Therefore, when the newly calculated expiration time ExpTim is registered in the DrxTime management table 201, if the expiration time ExpTim is compatible with the mobile communication terminal X, the DrxTime management is performed according to the process shown in FIG. The expiration times ExpTim are compared and rearranged in order from the top element 210 of the table 201 to the tail. Accordingly, the number of comparisons and rearrangements with the comparison elements may be reduced as compared with the case where the expiration times ExpTim are compared and rearranged sequentially from the last element 210 of the DrxTime management table 201 toward the top. it can. On the other hand, when the newly calculated expiration time ExpTim corresponds to the mobile communication terminals Y and Z, the expiration time ExpTim is compared in order from the last element 210 of the DrxTime management table 201 according to the processing of FIG. Sort. As a result, the number of comparisons and rearrangements can be reduced as compared with the case where the expiration times ExpTim are compared and rearranged in order from the first element 210 of the DrxTime management table 201.

FIG. 17 is a flowchart showing processing performed when the base station in the third embodiment registers the expiration time ExpTim in the DrxTime management table. The process of FIG. 17 corresponds to the process of registering the expiration time ExpTim newly calculated in FIGS. 9 to 11 in the DrxTime management table. 13 performs comparison and rearrangement of the expiration times ExpTim in order from the last element 210 of the DrxTime management table 201, whereas the process of FIG. 17 performs in order from the top element 210 of the DrxTime management table 201. Compare and sort expiry times ExpTim.

First, when a new expiration time ExpTim is calculated, the control unit 100 determines whether or not the number of elements 210 registered in the currently used state list 211 of the DrxTime management table 201 is 0 (step S300). If it is determined in S300 that the number of registrations is 0 (S300, Yes), the specified element 210 that associates the calculated expiration time ExpTim with the corresponding mobile communication terminal 20 is the last in the state list 211 that is currently in use. It arrange | positions at a tail (namely, head) (step S316), and complete | finishes a process.

On the other hand, if it is determined in S300 that the number of registered elements 210 in the currently used state list 211 for this mobile communication terminal 20 is not 0 (No in S300), the control unit 100 then tries to newly register. The expiration time ExpTim (A) of the element (hereinafter referred to as “designated element”) 210 to be read is read (step S301). Next, the control unit 100 sets the comparison element 210 as the head pointer of the currently used state list 211 (step S302), and reads the expiration time ExpTim (i) of the comparison element 210 (step S303). Next, the control unit 100 determines whether or not the expiration time ExpTim (A) of the designated element 210 matches the expiration time ExpTim (i) of the comparison element 210 (step S304). If it is determined in S304 that they do not match (S304, No), it is next determined whether or not the expiration time ExpTim (i) of the comparison element 210 is longer than the expiration time ExpTim (A) of the designated element 210 (step S305). . If it is determined in S305 that the expiry time ExpTim (i) of the comparison element 210 is shorter than the expiry time ExpTim (A) of the designated element 210 (S305, No), the comparison element 210 is set to the next element 210 ( Step S306). After S306, when the number of times of returning to S303 has not reached the number of registered elements 210, the process returns to S303. On the other hand, when the number of times of returning to S303 after S306 has reached the number of elements 210 registered in the in-use state list 211 in the DrxTime management table, the specified element 210 of the state list 211 currently in use It arrange | positions at the tail (step S307) and complete | finishes a process. On the other hand, if it is determined in S305 that the expiration time ExpTim (i) of the comparison element 210 is longer than the expiration time ExpTim (A) of the designated element 210, the designated element 210 is placed before the comparison element 210 (step S308). The process ends.

Since the processing of S309 to S315 is the same as the processing of S279 to 285 in FIG. 13, detailed description thereof will be omitted.

As described above, in the third embodiment, the base station 10 first calculates the cumulative distribution q of the existence probabilities of the plurality of mobile communication terminals 20 that perform radio communication with the own station, before the expiration time ExpTim is registered. This is obtained based on the state monitoring cycle Cycle and the number of communication terminals 20. Next, the base station 10 obtains a time t50 for the cumulative distribution 50% based on the cumulative distribution q of the existence probability of the mobile communication terminal 20. Next, the base station 10 determines which element at the head or tail of the DrxTime management table 201 is based on the comparison between the state monitoring cycle Cycle of the mobile communication terminal 20 corresponding to the expiration time ExpTim to be newly registered and the time t50. In order from 210, it is determined whether to compare and rearrange the expiration times ExpTim.

According to the third embodiment, in addition to the effects of the second embodiment, it is possible to reduce the burden of registration processing of the expiration time in the intermittent reception control of the base station.

In the present embodiment, the case where the transmission time interval (TTI) is implemented in LTE has been described. However, the present invention is not limited to the implementation in LTE and the transmission time interval. Any time interval may be used.

Embodiment 4 FIG.
In the second and third embodiments described above, in the process of registering the newly calculated expiration time ExpTim in the DrxTime management table 201 (FIGS. 13 and 17), when there are a plurality of elements 210 having the same expiration time ExpTim. Always, these expiry times ExpTim are shifted. However, if there are many elements 210 having the same expiration time ExpTim, the processing load on the base station 10 is high.

Therefore, the fourth embodiment is intended to further reduce the processing load of the base station 10 by allowing a predetermined number of elements 210 having the same expiration time ExpTim.

Embodiment 4 of the present invention will be described with reference to FIGS. The description will focus on the parts different from the first to third embodiments. The matters described with reference to FIGS. 1 to 3 and 9 to 12 are also applied to the fourth embodiment.

FIG. 18 is a graph showing the relationship between the density d of the mobile communication terminal and the time t in the case of FIG. FIG. 19 is a graph showing the relationship between the density d of the mobile communication terminal and the time t in the case of FIG. 18 and 19, the terminal congestion d (t) is
d (t) = int (P (t) + 1)
It is. Here, P (t) is the sum of the existence probabilities p (FIG. 14) of the mobile communication terminals X, Y, and Z. In the case of FIGS. 18 and 19, the terminal density d takes the maximum value d1 in the vicinity of time t = 0. Then, it is predicted that the number of mobile communication terminals 20 having the same expiration time ExpTim exists on average by d1. In the fourth embodiment, the number of mobile communication terminals 20 having the same expiration time ExpTim is allowed to exist up to the maximum value d1. That is, in the processing of FIG. 13, when the number of elements 210 having the same expiration time ExpTim is less than d1, these expiration times ExpTim are not shifted. On the other hand, if the number of elements 210 having the same expiration time ExpTim is equal to or greater than d1, the expiration times ExpTim are shifted until the number of elements 210 having the same expiration time ExpTim is at least less than d1. As a result, the processing load on the base station 10 can be reduced as compared with the case where the expiration time ExpTim is shifted for all the elements 210 having the same expiration time ExpTim.

Thus, in the fourth embodiment, the base station 10 first obtains the maximum value d1 of the terminal congestion d of the mobile communication terminal 20 before the registration of the expiration time ExpTim in the DrxTimer management table 201. Next, if the number of elements 210 having the same expiration time ExpTim as the expiration time ExpTim (A) of the newly registered element is equal to or greater than the maximum value d1 of the terminal congestion d, the elements already registered Compare with 210 and rearrange. On the other hand, when the number of elements 210 having the same expiration time ExpTim as the expiration time ExpTim (A) of the designated element 210 is less than the maximum value d1 of the terminal congestion d, the comparison with the elements 210 already registered is made. And no reordering.

According to the fourth embodiment, in addition to the effects of the second embodiment, it is possible to reduce the burden of registration processing of the expiration time in the intermittent reception control of the base station.

In the fourth embodiment, the maximum value d1 of the terminal congestion d is used as the threshold value. Alternatively, any predetermined value (<d1) may be used as the threshold value. Similar effects can be obtained.

In the present embodiment, the case where the transmission time interval (TTI) is implemented in LTE has been described. However, the present invention is not limited to the implementation in LTE and the transmission time interval. Any time interval may be used.

Further, in each of the above-described embodiments, for example, the meaning of the technical idea of the expression such as the predetermined value “greater than” or the predetermined value “less than” is not necessarily a strict meaning, and depends on the specifications of the base station, etc. In addition, the meaning when the reference value is included or not included is included. For example, the predetermined value “greater than or equal to” can be implied not only when the increasing value reaches the predetermined value but also when the predetermined value is exceeded. In addition, for example, the predetermined value “below” may imply not only when the decreasing value reaches the predetermined value, but also when the value decreases below the predetermined value, that is, when the value decreases below the predetermined value.

1 mobile communication system 10 base station 20 mobile communication terminal 100 control unit 200 storage unit 201 DrxTime management table 202 Drx setting value 210 element 211 status list 221 first setting value 222 second setting value

Claims (16)

A base station capable of wireless communication with a mobile communication terminal,
A storage unit for storing a first start timing to the mobile communication terminal in the first intermittent reception state of the mobile communication terminal;
A control unit that starts determining whether or not the mobile communication terminal is in the first intermittent reception state when the first start timing is reached when the mobile communication terminal is not in the intermittent reception state; Base station characterized by The storage unit further includes a second intermittent reception state of the mobile communication terminal having a second intermittent reception cycle that is longer than a first intermittent reception cycle of the first intermittent reception state. 2 start timing,
When the mobile communication terminal is in the first intermittent reception state, the control unit determines whether the mobile communication terminal is in the second intermittent reception state at the second start timing. The base station according to claim 1, wherein the base station starts. The storage unit stores a list in which a plurality of elements in which an expiration time defining the first start timing is associated with the mobile communication terminal are arranged in a short order of the expiration time,
The control unit compares the current time with the expiration time of the element in order from the first element of the list at predetermined time intervals, and corresponds to the element having an expiration time that matches the current time. When the mobile communication terminal is not in the intermittent reception state, the mobile communication terminal starts determining whether the mobile communication terminal is in the first intermittent reception state.
The base station according to claim 1. The storage unit stores a list in which a plurality of elements in which an expiration time that defines the first start timing or the second start timing is associated with the mobile communication terminal are arranged in order of short expiration time. ,
The control unit compares the current time with the expiration time of the element in order from the first element of the list at predetermined time intervals, and corresponds to the element having an expiration time that matches the current time. When the mobile communication terminal is not in the intermittent reception state, the mobile communication terminal starts determining whether or not the mobile communication terminal is in the first intermittent reception state, and the mobile communication terminal is in the first intermittent reception state Starts determining whether or not the mobile communication terminal is in the second intermittent reception state.
The base station according to claim 2. The storage unit further stores a first state monitoring period of each mobile communication terminal set to be the same as the first intermittent reception period in the first intermittent reception state of each mobile communication terminal. ,
The control unit calculates a new expiration time for an element having an expiration time that matches the current time at the predetermined time interval based on a first state monitoring period of the mobile communication terminal corresponding to the element. Then, the base station according to claim 3, wherein the elements of the list are rearranged so that the elements of the list are arranged in the order of shortest expiration time. The storage unit further includes a first state monitoring period of each portable communication terminal set to be the same as the first intermittent reception period in the first intermittent reception state of each portable communication terminal; Storing a second state monitoring period of each mobile communication terminal set to be the same as the second intermittent reception period in the second intermittent reception state of the mobile communication terminal;
For each element having an expiration time that coincides with the current time for each predetermined time interval, the control unit further determines the number of the mobile communication terminal when the mobile communication terminal corresponding to the element is not in an intermittent reception state. A new expiration time is calculated based on the state monitoring cycle of 1, and if the mobile communication terminal corresponding to the element is in the first intermittent reception state, a new expiration time is calculated based on the second state monitoring cycle of the mobile communication terminal. 5. The base station according to claim 4, wherein a base expiration time is calculated, and thereafter, the elements of the list are rearranged so that the elements of the list are arranged in the order of shortest expiration time. After calculating the new expiration time, the control unit, based on the cumulative distribution of the existence probability of each mobile communication terminal obtained from the first state monitoring period and the number of each mobile communication terminal, 6. The base station according to claim 5, wherein the base station determines whether to perform the rearrangement by comparing the expiration time of the element and the new expiration time in order from either the first element or the last element. . After calculating the new expiration time, the control unit, when there are a predetermined number of elements having an expiration time that matches the new expiration time in the list, the same expiration time as the new expiration time 6. The base station according to claim 5, wherein the rearrangement is performed by shifting expiration times of the elements so that the number of elements having a value is less than the predetermined number. A base station control method capable of wireless communication with a mobile communication terminal,
When the mobile communication terminal is not in the intermittent reception state, the mobile communication terminal is in the first intermittent reception state at the first start timing for the mobile communication terminal in the first intermittent reception state of the mobile communication terminal. A control method for a base station, comprising the step of starting a determination as to whether or not the mobile station is in the base station. When the portable communication terminal is in the first intermittent reception state, the second intermittent reception of the portable communication terminal having a second intermittent reception cycle longer than the first intermittent reception cycle of the first intermittent reception state. The step of starting whether or not the mobile communication terminal is in the second intermittent reception state at a second start timing for the mobile communication terminal in a state is provided. The control method of the base station as described in 2. For each predetermined time interval, a plurality of elements in which an expiration time defining the first start timing and the mobile communication terminal are associated with each other are arranged in order from the shortest expiration time, in order from the first element in the list. Comparing the time with the expiration time of the element;
As a result of the comparison, for an element having an expiration time that matches the current time, if the mobile communication terminal corresponding to the element is not in the intermittent reception state, whether or not the mobile communication terminal is in the first intermittent reception state The step of starting the determination of
The base station control method according to claim 9, further comprising: For each predetermined time interval, the head of a list in which a plurality of elements in which expiration times defining the first start timing or the second start timing are associated with the mobile communication terminal are arranged in the order of short expiration time Comparing the current time with the expiration time of the element, in order from the element of
As a result of the comparison, for an element having an expiration time that matches the current time, if the mobile communication terminal corresponding to the element is not in the intermittent reception state, whether or not the mobile communication terminal is in the first intermittent reception state Starting the determination, and if the mobile communication terminal is in the first intermittent reception state, starting the determination whether the mobile communication terminal is in the second intermittent reception state;
The base station control method according to claim 10, further comprising: As a result of the comparison, for the element having an expiration time that matches the current time, the portable communication terminal set to be the same as the first intermittent reception cycle in the first intermittent reception state of the portable communication terminal corresponding to the element Calculating a new expiration time based on the first state monitoring period of:
Rearranging the elements of the list so that the elements of the list are arranged in the order of shortest expiration time;
The base station control method according to claim 11, further comprising: As a result of the comparison, when the mobile communication terminal corresponding to the element is not in the discontinuous reception state for the element having the expiration time that matches the current time, the first discontinuous reception state of the mobile communication terminal in the first discontinuous reception state When a new expiration time is calculated based on the first state monitoring cycle of the mobile communication terminal set to be the same as the intermittent reception cycle, and the mobile communication terminal corresponding to the element is in the first intermittent reception state, Calculating a new expiration time based on the second state monitoring period of the mobile communication terminal set to be the same as the second intermittent reception period in the second intermittent reception state of the mobile communication terminal;
Rearranging the elements of the list so that the elements of the list are arranged in the order of shortest expiration time;
The base station control method according to claim 12, further comprising: After calculating the new expiration time, based on the cumulative distribution of the existence probabilities of each mobile communication terminal obtained from the first state monitoring period and the number of each mobile communication terminal, The base station control method according to claim 13, wherein the base station control method determines whether to perform the rearrangement by comparing the expiration time of the element and the new expiration time in order from any element. After calculating the new expiration time, the number of elements having the same expiration time as the new expiration time when there are a predetermined number or more of elements having an expiration time that matches the new expiration time in the list The base station control method according to claim 13, wherein the rearrangement is performed by shifting expiration times of the elements so as to be less than the predetermined number.

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