WO2013111659A1

WO2013111659A1 - Wireless terminal, control method, and recording medium

Info

Publication number: WO2013111659A1
Application number: PCT/JP2013/050744
Authority: WO
Inventors: 高志唯木
Original assignee: Ｎｅｃカシオモバイルコミュニケーションズ株式会社
Priority date: 2012-01-27
Filing date: 2013-01-17
Publication date: 2013-08-01

Abstract

A communication control unit (102) executes a cell reselection which selects a suitable cell on the basis of prescribed conditions while a wireless terminal is in a cell coverage area. A data storage unit (104) associates operating conditions of the wireless terminal with current consumption values of the wireless terminal and stores same. After the wireless terminal is present in the suitable cell area after the cell reselection, a determination unit (105) derives from the data storage unit (104) a current consumption value corresponding to the terminal operating conditions when in the cell coverage area prior to the cell reselection as a first current consumption value and a current consumption value corresponding to the terminal operating conditions when in the suitable cell as a second current consumption value and compares the two current consumption values. When the determination unit (105) determines that the second current consumption value is greater than the first current consumption value, the communication control unit (102) retains the wireless terminal in the coverage area of the suitable cell, and when the determination unit (105) determines that the second current consumption value is less than the first current consumption value, the communication control unit (102) once again places the wireless terminal in the coverage area of the cell prior to carrying out the reselection.

Description

Wireless terminal, control method and recording medium

The present invention relates to a wireless terminal, a control method, and a recording medium.

In wireless communication in a wireless terminal, the communication state is successively switched according to the connection state with the network (hereinafter, NW) side. For example, in W-CDMA (Wideband Code Division Multiple Access), which is one of the cellular systems, as a communication state, as described in Non-Patent Document 1, Cell-DCH (Dedicated CH annel) state, Cell-FACH There are Forward Access CHannel state, Cell-PCH (Paging CHannel) state, idle state, and so on.

The W-CDMA wireless terminal is generally in idle state when there is no data transmission / reception. This is to reduce the current consumed by the portable wireless terminal. Also, in wireless communication such as LTE (Long Term Evolution) and GSM (registered trademark) / GPRS (Global System for Mobile communications / General Packet Radio Service), as in the idle state of W-CDMA, communication with low current consumption. There is a state.

However, even in the idle state, the wireless terminal periodically performs Paging Channel monitoring such as notification of incoming call, notification of change of broadcast information, notification of ETWS (Earthquake Tsunami Warning System) notification, and monitoring of electric fields of neighboring cells. Perform intermittent reception (DRX).

Furthermore, the wireless terminal monitors the electric field of the neighboring cells in the idle state, and when the electric field quality of the cell currently located is deteriorated due to movement or the like, the wireless terminal is located in a cell with a stronger electric field, Perform Cell Reselection to reselect cells. Cell Reselection is defined as a specification of 3rd Generation Partnership Project (3GPP). The wireless terminal determines a cell that satisfies the predetermined condition as a new cell based on the parameter included in the broadcast information notified from the NW and the measurement result of the electric field of the peripheral cell of the wireless terminal.

By the way, a communication standard of wireless communication access such as W-CDMA and LTE is called RAT (Radio Access Technology). While there are NWs and wireless terminals that support only wireless communication between the same RAT, there are NWs and wireless terminals that support multiple RATs. The NW and the wireless terminal supporting multiple RATs are not limited to Cell Reselection (eg, cell change between W-CDMA cells) in the same RAT, but also Cell Reselection (eg, It is possible to execute the change of W-CDMA cell to LTE cell).

For example, the wireless terminal performs Qoffset (offset value of electric field strength) notified by broadcast information from the NW side at the time of executing Cell Reselection from the cell of W-CDMA which is the same RAT to the cell of W-CDMA. Each cell is ranked according to parameters (refer to 3GPP TS 25. 304) such as (hysteresis value), HCS_PRIO (hierarchized cell priority level), and cells are selected based on the ranked result.

Also, in order to determine a serving cell, ie, a serving cell, in Cell Reselection, for example, the following determination formula is used. Here, Rs is a determination value of a Serving Cell, that is, a cell currently located, and Rn is a determination value of a Neighboring Cell, that is, a cell adjacent to the currently located cell. Also, Qmeas is the measured electric field value of the cell. Among these, Qmeas, s is the electric field value of the present cell, and Qmeas, n is the electric field value of the adjacent cell. Also, Qhysts is a hysteresis value, and Qoffsets, n is an offset value between cells.

Serving Cell: Rs = Qmeas, s + Qhysts

Neighboring Cell: Rn = Qmeas, n + Qoffsets, n

Next, the wireless terminal compares the determination value of each cell obtained from the above determination formula, and the determination value of the adjacent cell exceeds the determination value of the current cell for a predetermined time (Rn> Rs), When the predetermined time has elapsed, it is determined that the electric field strength of the Neighboring Cell is stronger than the electric field strength of the Serving Cell. Then, the wireless terminal changes the current location to the relevant cell.
Although not included in the above judgment formula, a parameter such as HCS_PRIO (hierarchized cell priority level) may be used in order to consider the priority for each cell.

Furthermore, in Cell Reselection between different RATs such as LTE and W-CDMA cells, it is possible to add priority to each RAT. For example, in an area in which LTE and W-CDMA cell allocations overlap, a parameter is set as a determination formula that makes it easier to execute Cell Reselection from the W-CDMA cell to the LTE cell that is a high throughput environment. be able to.

Also, conversely, it is possible to set parameters that facilitate Cell Reselection from the LTE cell to the W-CDMA cell. As described above, these parameters are determined by the parameters of the standard specification defined in 3GPP and the parameters included in the broadcast information notified from the NW side (in the case of LTE, refer to 3GPP TS 36.304). As described above, Cell Reselection largely depends on the operation policy on the NW side.

In addition, the current consumption of the wireless terminal is different for each RAT due to the difference in communication scheme. Furthermore, even in the same RAT, the consumption current of the idle state fluctuates largely depending on the conditions under which the wireless terminal operates (hereinafter, terminal operating conditions). For example, in LTE, the frequency bandwidth to be used, DRX length which is the period of intermittent operation, the number of antennas to be used, etc. become parameters indicating the terminal operating condition. The current consumption of the wireless terminal differs greatly depending on the combination of these. The number of antennas may be switched inside the terminal according to the environment such as the number of neighboring cells to be measured or the reception electric field, for example, in a wireless terminal adopting MIMO (Multiple Input Multiple Output).

Parameters of terminal operation conditions of W-CDMA include DRX length, the number of neighboring cells to be measured, and the number of antennas to be used. In addition, since the frequency bandwidth to be used is fixed in W-CDMA, the frequency bandwidth is not included in the parameters. Further, the parameters of GSM (registered trademark) / GPRS include a Paging cycle, the number of neighboring cells to be measured, and a decode cycle of BCCH / BCH (Broadcast Control Channel / Synchronization Channel) of each cell. The Paging cycle corresponds to the DRX length of W-CDMA.

The consumption current differs depending on the combination of parameters indicating the terminal operating conditions as described above. In general, terminal operating conditions such as a narrow frequency bandwidth, a long DRX length, and a small number of antennas consume less current. The parameters indicating the terminal operating conditions are different for each communication method of LTE, W-CDMA and GSM (registered trademark) / GPRS, but in any communication method, patterns of current consumption exist for the number of combined parameters .

As described above, the current consumption of the wireless terminal differs depending on the terminal operating conditions, and the power consumption also differs accordingly. In addition, since wireless terminals often operate by battery operation, it is required to operate to suppress power consumption.
However, in Cell Reselection prescribed by 3GPP, a cell to be a new access point is determined according to the operation policy of the NW, and terminal operation conditions of each wireless terminal are not considered. Moreover, it is difficult for the NW side to grasp the terminal operation conditions of each wireless terminal. For this reason, even in the idle state where the current consumption can be suppressed, it can not always be said that the optimal cell in consideration of the power consumption state is selected at the time of executing the Cell Reselection.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a wireless terminal, a control method and a recording medium which can further optimize the power consumption state.

In order to achieve the above object, a wireless terminal according to a first aspect of the present invention,
A wireless terminal that performs cellular wireless communication, and
A communication control unit that performs cell reselection to select an appropriate cell found under a predetermined condition while the wireless terminal is in a cell, and controls the wireless terminal to stay in the appropriate cell;
A data storage unit that associates and stores a condition under which the wireless terminal operates and a current consumption value indicating the current consumed by the wireless terminal;
After the communication control unit performs the cell reselection and controls the wireless terminal such that the wireless terminal is located in the appropriate cell, the wireless terminal is a cell that was present before the cell reselection was performed. The current consumption value corresponding to the condition in which the wireless terminal operates in the cell before cell reselection is the first current consumption value, and the current consumption value corresponding to the condition in which the wireless terminal operates in the appropriate cell is the second A determination unit that determines, from the data storage unit, a current consumption value of the second current consumption value, and determines whether the second current consumption value is smaller than the first current consumption value;
Equipped with
When the determination unit determines that the second consumption current value is smaller than the first consumption current value, the communication control unit is as it is in the appropriate cell, and the second consumption current value If it is determined that the current consumption value is not smaller than the first consumption current value, the wireless terminal is controlled to re-visit the cell before the cell reselection,
It is characterized by

Further, the control method according to the second aspect of the present invention is
A control method of a wireless terminal performing wireless communication in a cellular system, comprising:
A communication control step of performing cell reselection to select an appropriate cell found under a predetermined condition while the radio terminal is in a cell, and controlling the radio terminal to be in the appropriate cell; ,
In the communication control step, after the cell reselection is performed and the wireless terminal is controlled to be located in the appropriate cell, the wireless stored in association with each of the conditions under which the wireless terminal operates. The consumption current value indicating the current consumed by the terminal is associated with the condition under which the radio terminal operates in the cell before cell reselection which is the cell in which the radio terminal was located before the cell reselection. Obtaining a first current consumption value which is the current consumption value, and a second current consumption value which is the current consumption value associated with the condition under which the wireless terminal operates in the appropriate cell; A determination step of determining whether the current consumption value of 2 is smaller than the first current consumption value;
If it is determined in the determination step that the second consumption current value is smaller than the first consumption current value, the appropriate cell is located as it is, and the second consumption current value is determined in the determination step. A control step of controlling the wireless terminal to revisit the cell before the cell reselection if it is determined that the current consumption value is not smaller than the first current consumption value;
It is characterized by including.

Moreover, a computer readable recording medium according to the third aspect of the present invention is
In a wireless terminal performing wireless communication in a cellular system,
A communication control function of performing cell reselection to select an appropriate cell found based on a predetermined condition while the wireless terminal is in a cell, and controlling to locate the appropriate cell;
A data storage function that stores the condition under which the wireless terminal operates and the current consumption value indicating the current consumed by the wireless terminal in association with each other;
After the cell reselection is performed by the communication control function and the radio terminal is controlled to be located in the appropriate cell, the cell in which the radio terminal was located before the cell reselection is performed A consumption current value corresponding to a condition for the wireless terminal to operate in a cell before a certain cell reselection is a first consumption current value, and a consumption current value corresponding to the condition for the wireless terminal to operate in the appropriate cell is A determination function of determining the consumption current value stored in the data storage function as the consumption current value of 2, and determining whether the second consumption current value is smaller than the first consumption current value;
To achieve
The communication control function controls to be in the proper cell as it is when the determination function determines that the second consumption current value is smaller than the first consumption current value, and the determination function Control the wireless terminal to revisit the cell of the cell reselection if it is determined that the second consumption current value is not smaller than the first consumption current value.
It is characterized in that the program is recorded.

According to the present invention, power consumption can be further optimized.

It is a block diagram showing a schematic structure of a portable radio terminal concerning an embodiment. It is a figure which shows an example of the consumption current table stored in the data storage part of FIG. It is a flowchart which shows operation | movement of the portable radio | wireless terminal of FIG. It is a flowchart which shows operation | movement of the communication control part of FIG. It is a flowchart which shows operation | movement of the determination part of FIG. It is a flowchart which shows operation | movement of the data processing part of FIG.

Hereinafter, a portable radio terminal 100 will be described as an example of the radio terminal according to the present invention.
The mobile radio terminal 100 has a function of executing Cell Reselection defined as a specification of 3GPP.

As shown in FIG. 1, the mobile wireless terminal 100 includes a wireless unit 101, a communication control unit 102, and a control unit 103.

The wireless unit 101 performs wireless communication with a mobile communication network 200 (hereinafter referred to as NW 200) in which a plurality of base station cells (hereinafter referred to as cells) are formed. Under the control of the communication control unit 102, the wireless unit 101 is located in at least one of the plurality of cells, and performs wireless communication with the NW 200 via the base station of the located cell. The wireless unit 101 supports multiple RATs such as W-CDMA, LTE, and GSM (registered trademark) / GPRS.
The wireless unit 101 receives, for example, broadcast information notified from the NW 200 at the time of executing Cell Reselection.

The communication control unit 102 controls overall wireless communication via the wireless unit 101. This control includes the control of Cell Reselection defined as the 3GPP specification. Specifically, the communication control unit 102 changes the service area of the mobile terminal 100 to a cell selected as a new service area by Cell Reselection (hereinafter, referred to as a new serving cell).
Further, the communication control unit 102 changes the service area destination of the portable terminal 100 based on the determination result of the determination unit 105 described later. Specifically, when the communication control unit 102 determines that the new serving cell is not optimal as the destination, the communication control unit 102 locates the location where the mobile terminal 100 is located before performing Cell Reselection. Change to the serving cell (hereinafter referred to as serving cell before cell reselection).
Further, the communication control unit 102 notifies each unit of the portable wireless terminal 100 of various information and the like acquired via the wireless unit 101. For example, the communication control unit 102 notifies the data processing unit 106 of broadcast information and the like from the NW 200.
The communication control unit 102 has a memory in which a program for the computer to realize the function of the communication control unit 102 is stored. The function of the communication control unit 102 is realized by the CPU of the computer executing the program stored in the memory.

The control unit 103 controls the entire mobile wireless terminal 100. As shown in FIG. 1, the control unit 103 includes a data storage unit 104, a determination unit 105, and a data processing unit 106. The control unit 103 has a memory in which a program that causes a computer to realize the function of the control unit 103 is stored. The function of the control unit 103 is realized by the CPU of the computer executing the program stored in the memory. Note that the computer that implements the function of the communication control unit 102 and the computer that implements the function of the control unit 103 may be the same computer or separate computers.

Data storage unit 104 stores a current consumption value indicating the current consumed by portable wireless terminal 100 according to the terminal operation condition. The data storage unit 104 holds parameters indicating terminal operating conditions and current consumption values, for example, in the current consumption table shown in FIG.

As shown in FIG. 2, in the consumption current table, the number of antennas, frequency bandwidth, and DRXlength which is a cycle of intermittent operation are stored as terminal operation conditions. Here, one or two antennas are set. In addition, as the frequency bandwidth, 1.4, 3, 5, 10, 15, and 20 MHz are set. Moreover, 320, 640, 1280, and 2560 ms are set as DRX length. In this table, the current consumption value is set for each combination of these parameters. In the consumption current table shown in FIG. 2, three types of parameters, the number of antennas, the frequency bandwidth, and the DRX length, are used. However, parameters indicating terminal operating conditions are not limited to these. Also, the types of parameters may be more or less than the example shown in FIG.

In addition to the above, as parameters indicating terminal operating conditions, for example, type of RAT, Sintrasearch (Sintersearch, Ssearchrat), whether or not there is an environment with neighboring cell search, and an environment with a neighboring cell search There is the number of cells, etc.

Refer back to FIG.
The data processing unit 106 decodes broadcast information and internal information (number of antennas etc.) notified from the communication control unit 102, extracts information necessary for specifying a terminal operation condition, and determines the extracted information as the determination unit 105. To notify. Here, the broadcast information is broadcast information (hereinafter, referred to as broadcast information of a new serving cell) acquired from the NW 200 by the communication control unit 102 when the service area is located in a new serving cell.

The determination unit 105 specifies a terminal operation condition in the serving cell before cell reselection based on various information on the serving cell before cell reselection. The various information on the serving cell before cell reselection is information such as the number of antennas, RAT, cell ID and the like. These pieces of information are included, for example, in the information notified from the data processing unit 106 at the time of the previous Cell Reselection. In addition, after the cell in which portable radio terminal 100 is located is changed to a new serving cell, determination section 105 is a terminal in the new serving cell based on decoded broadcast information etc. notified from data processing section 106. Identify operating conditions. At the same time, the notification information notified from the data processing unit 106 is held. The determination unit 105, for example, uses the held information as information on a serving cell before cell reselection in the next execution of Cell Reselection.

Furthermore, the determination unit 105 determines the consumption current value corresponding to the terminal operation condition in the serving cell before cell reselection (hereinafter referred to as the consumption current value in the serving cell before cell reselection) and the terminal operation in the new serving cell. The current consumption value corresponding to the condition (hereinafter referred to as the current consumption value in the new serving cell) is obtained from the data storage unit 104. Then, the determination unit 105 compares these current consumption values. If the consumed current value in the new serving cell is smaller than the consumed current value in the serving cell before cell reselection, the determination unit 105 determines that serving in the new serving cell is optimal. On the other hand, when the consumption current value in the new serving cell is not smaller than the consumption current value in the serving cell before cell reselection, the determination unit 105 determines that locating in the new serving cell is not optimal. The determination unit 105 notifies the communication control unit 102 of the determination result.

Next, the operation of the mobile wireless terminal 100 according to the present embodiment will be described. FIG. 3 shows an outline of a flow of processing in which the mobile radio terminal 100 according to the present embodiment selects an optimal cell when executing Cell Reselection.

The mobile radio terminal 100 monitors neighboring cells in the idle state, and does not start a series of processing described later until finding neighboring cells satisfying the condition of Cell Reselection (step S1; No).

When mobile radio terminal 100 finds a neighboring cell that satisfies the condition (step S1; Yes), it specifies a terminal operation condition in the serving cell before cell reselection (step S2). In addition, the mobile radio terminal 100 changes the located area to the neighboring cell that satisfies the condition of Cell Reselection.

Subsequently, the mobile wireless terminal 100 acquires broadcast information of a new serving cell from the NW 200 (step S3).

The mobile radio terminal 100 specifies a terminal operation condition in a new serving cell based on the acquired broadcast information (step S4).

Subsequently, the portable radio terminal 100 refers to the consumption current table of the data storage unit 104, and identifies in step S4 the consumption current value corresponding to the terminal operation condition in the serving cell before cell reselection identified in step S2. The current consumption value corresponding to the terminal operating condition in the new serving cell is acquired (step S5).

Subsequently, the mobile wireless terminal 100 compares the current consumption value in the serving cell before cell reselection acquired in step S5 with the current consumption value in the new serving cell (step S6).
The mobile radio terminal 100 determines whether or not the new serving cell selected in the current Cell Reselection is optimal based on the result of comparing the current consumption values (step S7).

If the mobile radio terminal 100 determines that the new serving cell selected in the current Cell Reselection is optimal (step S7; Yes), it determines that the mobile radio terminal 100 continues to be in the new serving cell (step S8). Thereafter, the portable radio terminal 100 returns to step S1.

On the other hand, when the mobile radio terminal 100 determines that the new serving cell selected by the current Cell Reselection is not optimal (Step S7; No), the mobile radio terminal 100 changes the located area to the serving cell before cell reselection (Step S9).

Furthermore, after changing to the serving cell before cell reselection again, the portable radio terminal 100 suppresses Cell Reselection to the new serving cell again for a predetermined time (step S10). That is, the new serving cell is temporarily not selected by Cell Reselection. After execution of step S10, the portable radio terminal 100 returns to step S1.

Thereafter, while in the idle state, the mobile wireless terminal 100 repeats the series of operations from step S1 to step S10 described above.

The flow in which the respective units of the mobile wireless terminal 100 cooperate and execute the above-described process illustrated in FIG. 3 will be described in more detail. FIG. 4 shows an example of the operation flow of the communication control unit 102. FIG. 5 shows an example of the operation flow of the determination unit 105. FIG. 6 shows an example of the operation flow of the data processing unit 106.

As shown in FIG. 4, first, the communication control unit 102 periodically performs, for example, monitoring of neighboring cells until a cell satisfying the condition of Cell Reselection is found (step S11; No). When a cell satisfying the condition of Cell Reselection is found (step S11; Yes), the communication control unit 102 executes cell reselection (hereinafter referred to as “Cell Reselection trigger”), or the serving cell before reselection to the currently located cell. The hardware information such as the reception electric field and the number of used antennas is notified to the determination unit 105 (step S12).

As illustrated in FIG. 5, the determination unit 105 is waiting for notification of a Cell Reselection trigger from the communication control unit 102 (step S31; No). When the determination unit 105 is notified of the Cell Reselection opportunity from the communication control unit 102 (step S31; Yes), the cell reselection is performed based on the simultaneously notified hardware information, the RAT already held, the cell ID, and the like. The terminal operating condition in the serving cell before selection is specified (step S32). Thereafter, the determination unit 105 waits for notification of information on a new serving cell (step S33; No).

As shown in FIG. 4, the communication control unit 102 executes Cell Reselection, and changes the cell in the serving area to a new serving cell (step S13). Subsequently, the communication control unit 102 waits until broadcast information of a new serving cell can be acquired from the NW 200 (step S14; No).

If the communication control unit 102 acquires the broadcast information (step S14; Yes), the communication control unit 102 notifies the determination unit 105 of hardware information such as the reception electric field of the new serving cell currently located and the number of antennas used (step S15). Furthermore, notification information of a new serving cell acquired from the NW 200 is notified to the data processing unit 106 (step S16). After that, the communication control unit 102 temporarily suspends the subsequent processing until the determination unit 105 is notified of the determination result as to whether or not the new serving cell selected by the current Cell Reselection is optimal, and the communication control unit 102 It waits for notification of the determination result (step S17; No).

On the other hand, as shown in FIG. 6, the data processing unit 106 waits until notification information is notified from the communication control unit 102 (step S51; No). When the notification information is notified (step S51; Yes), the data processing unit 106 decodes the notification information notified (step S52), and extracts information necessary for specifying the terminal operation condition (step S53). The information necessary for specifying the terminal operation condition includes, for example, DRX length, the number of neighboring cells to be monitored, Sintrasearch (Sintersearch, Sseachrat), frequency bandwidth (LTE only), and the like.

Subsequently, the data processing unit 106 notifies the determination unit 105 of information necessary for specifying the extracted terminal operation condition (step S54). After step S54, the data processing unit 106 returns to step S51.

As shown in FIG. 5, the determination unit 105 is notified when various information for specifying the terminal operating condition of the new serving cell is notified from the communication control unit 102 and the data processing unit 106 (step S33; Yes). The terminal operation condition in the new serving cell is specified based on the various information (step S34). That is, here, values of various parameters indicating terminal operating conditions in the new serving cell are acquired.

The determination unit 105 refers to the data storage unit 104 to determine the consumption current value corresponding to the terminal operation condition in the serving cell before cell reselection identified in step S32, and the terminal operation in the new serving cell identified in step S34. The current consumption value corresponding to the condition is acquired (step S35).

The determination unit 105 compares the current consumption values acquired in step S35 (step S36). Specifically, the determination unit 105 determines whether the current consumption value in the new serving cell is smaller than the current consumption value in the serving cell before cell reselection. Subsequently, based on the comparison result, the determination unit 105 determines whether the new serving cell selected by the current Cell Reselection is optimal (step S37). Here, when the consumed current value in the new serving cell is smaller than the consumed current value before cell reselection, the determination unit 105 determines that the new serving cell is optimal as a serving location.

For example, in steps S36 and S37, the determination unit 105 performs comparison and determination using the following determination formula. Here, I_a is a consumption current value in the serving cell before cell reselection. Also, I_b is a current consumption value in a new serving cell. C is a correction value.
I_a> I_b + C (1)
If the current consumption value acquired in step S35 satisfies the above equation (1), the determination unit 105 determines that the new serving cell selected by the current cell reselection is optimal. Note that the correction value C is a value that changes according to the relationship between the serving cell before cell reselection and the new serving cell, and can take either a positive or negative value. For example, the value of C may be changed according to the relationship between the received electric field of the serving cell before cell reselection and the received electric field of the new serving cell. Further, in the case of cell transition between different RATs, for example, C> 0 may be set from W-CDMA cell to LTE cell, C <0 from LTE cell to W-CDMA cell, or the like. In this way, it may be possible to keep on staying in the RAT where the current consumption can be further reduced.

If the determination unit 105 determines that the new serving cell selected by the current cell reselection is optimal as a result of the comparison of the current consumption values (step S37; Yes), the communication control unit 102 changes the location destination. It notifies that it is unnecessary (step S38). Further, the determination unit 105 holds various information used to specify the terminal operation condition in the serving cell before cell reselection in step S32 (step S39).

As shown in FIG. 4, when the communication control unit 102 receives a notification from the determination unit 105 (step S17; Yes), and when it is notified that the change of the service area destination is unnecessary (step S18; No) Resume the process, complete the process of determining whether the new serving cell is appropriate, and return to step 11.

On the other hand, as shown in FIG. 5, when the determination unit 105 determines that the new serving cell selected by the current Cell Reselection is not optimal as a result of the comparison of the consumption current values (step S36) (step S37; No) And notifies the communication control unit 102 to change the serving cell to the serving cell before cell reselection (step S40). Further, the determination unit 105 holds various information used to specify the terminal operation condition in the new serving cell in step S34 (step S41).

As shown in FIG. 4, when the communication control unit 102 receives a notification from the determination unit 105 (step S17; Yes) and the notification from the determination unit 105 is a change to a serving cell before cell reselection (step S18). Yes) Change the service area destination to the serving cell before cell reselection (step S19).

Furthermore, after changing the cell in the serving area to the serving cell before the cell reselection, the communication control unit 102 performs control so as not to temporarily exist in the new serving cell (step S20). Specifically, in the subsequent measurement of neighboring cells, weighting is performed such that it is difficult to exclude the new serving cell from the measurement target for a predetermined time or to locate the new serving cell. There are various methods for suppressing Cell Reselection for a specific cell. For example, the cell may not be targeted for monitoring. In addition, weighting may be performed on parameters used for determination of 3GPP-specified Cell Reselection, so that Cell Reselection may not be easily performed.
Thereafter, the communication control unit 102 completes the process of determining whether the new serving cell according to the present embodiment is appropriate, and returns to step 11.

As described above in detail, according to the present embodiment, the consumption current values of the serving cell before cell reselection and the new serving cell are compared, and based on the comparison result, the power consumption state is the optimum cell. Since it will be located, power consumption can be further optimized.

Further, according to the present embodiment, for example, when data of the current consumption value is stored in the current consumption table, the type of RAT can be stored as a parameter indicating the terminal operation condition. When executing Cell Reselection between different RATs, the terminal operating conditions are specified by parameters including the type of RAT, and the current consumption value is acquired. Therefore, in Cell Reselection between different RATs, it is possible to locate a cell of a RAT with a lower current consumption value. Thereby, a high power saving effect adapted to the current situation of each mobile wireless terminal 100 can be expected.

For example, in the case of an area where the W-CDMA cell and the LTE cell overlap, such an operation on the NW 200 side promotes transition to the LTE cell even if the electric field of the W-CDMA cell is not significantly degraded. It is highly likely that the Cell Reselection parameter has been set. However, temporarily, the current consumed in the idle state of the portable radio terminal 100 is much higher when existing in the LTE cell than when existing in the W-CDMA cell. Then, the current consumption can be reduced by continuing to stay in the W-CDMA cell. Thus, optimization of cell reselection can be realized from the viewpoint of current consumption.

Moreover, according to this embodiment, it is determined whether or not the new serving cell after the execution of Cell Relsection is optimal using the parameters included in the broadcast information. For example, the frequency bandwidth, DRX length, Sintraserach, Sintersearch, Ssearchrat, the number of neighboring cells, and the like. These are parameters that greatly affect the current consumption. Therefore, it is possible to realize optimization of cell reselection in terms of current consumption also for Cell Relsection in the same RAT.

In the above embodiment, Cell Reselection in the idle state has been described. However, the present invention can be applied to a communication state in which Cell Reselection exists, as in the idle state, such as the Cell-PCH state and the Cell-FACH state of W-CDMA.

Moreover, in the mobile radio terminal 100 according to the above-described embodiment, as a result of changing the existing cell back to the serving cell before the cell reselection again after cell reselection, it may be considered that the existing destination becomes out of range. When performing cell reselection, if the received electric field of the serving cell before the cell reselection is less than or equal to a certain threshold, the communication control unit 102 may trigger the cell reselection, the received electric field of the current cell, or the antenna used. The hardware information such as the number may not be notified to the determination unit 105. Therefore, the determination unit 105 does not determine the current consumption of the serving cell before cell reselection and the new serving cell. In this way, the destination can be prevented from going out of range.

Furthermore, the wireless terminal according to the present invention may be configured by installing a program for executing the processing in the above-described embodiment in the wireless terminal. For example, a program for causing a computer capable of wireless communication to execute the above-described operation may be a flexible disk, a compact disc read-only memory (CD-ROM), a digital versatile disc (DVD), a magneto-optical disc (MO), or the like. A wireless terminal that executes the above-described processing may be configured by storing and distributing the program in a computer readable recording medium and installing the program in the computer.

In addition, a method for providing a program to a computer capable of wireless communication is arbitrary. For example, the program may be stored in a disk device or the like included in a predetermined server device on a communication network such as the Internet, and may be distributed to a computer capable of wireless communication via a communication line. The program may be transmitted as a modulated wave in which a carrier wave is modulated by a signal representing the program, and a computer capable of wireless communication that has received the modulated wave may demodulate the modulated wave to restore the program. Then, the computer capable of wireless communication starts this program and executes it under the control of the OS in the same manner as other applications. Thus, the computer capable of wireless communication functions as a wireless terminal that executes the above-described processing.

In addition, when the OS (Operating System) shares and realizes the above-mentioned functions or when the OS and an application cooperate to realize it, etc., only the part other than the OS is stored and distributed in the recording medium. Or may be distributed via a communication line.

The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the present invention. In addition, the embodiment described above is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is indicated not by the embodiments but by the claims. And, various modifications applied within the scope of the claims and the meaning of the invention are considered to be within the scope of the present invention.

Although a part or all of the above-mentioned embodiment may be described as the following supplementary notes, it is not limited to the following.

(Supplementary Note 1)
A wireless terminal that performs cellular wireless communication, and
A communication control unit that performs cell reselection to select an appropriate cell found under a predetermined condition while the wireless terminal is in a cell, and controls the wireless terminal to stay in the appropriate cell;
A data storage unit that associates and stores a condition under which the wireless terminal operates and a current consumption value indicating the current consumed by the wireless terminal;
After the communication control unit performs the cell reselection and controls the wireless terminal such that the wireless terminal is located in the appropriate cell, the wireless terminal is a cell that was present before the cell reselection was performed. The current consumption value corresponding to the condition in which the wireless terminal operates in the cell before cell reselection is the first current consumption value, and the current consumption value corresponding to the condition in which the wireless terminal operates in the appropriate cell is the second A determination unit that determines, from the data storage unit, a current consumption value of the second current consumption value, and determines whether the second current consumption value is smaller than the first current consumption value;
Equipped with
When the determination unit determines that the second consumption current value is smaller than the first consumption current value, the communication control unit is as it is in the appropriate cell, and the second consumption current value If it is determined that the current consumption value is not smaller than the first consumption current value, the wireless terminal is controlled to re-visit the cell before the cell reselection,
A wireless terminal characterized by

(Supplementary Note 2)
The communication control unit controls the appropriate cell not to be selected in cell reselection for a predetermined time when the radio terminal is controlled to revisit the cell before the cell reselection after the cell reselection. ,
The wireless terminal according to appendix 1, characterized in that

(Supplementary Note 3)
The communication control unit further acquires broadcast information from a network while the wireless terminal is in a cell.
The determination unit specifies a condition under which the wireless terminal operates in the cell before cell reselection, based on the broadcast information acquired while the wireless terminal is in the cell before the cell reselection. After the communication control unit performs the cell reselection and controls the wireless terminal to locate the appropriate cell, based on the broadcast information acquired by the wireless terminal in the appropriate cell. And identifying the conditions under which the wireless terminal operates in the appropriate cell, and holding the broadcast information acquired by the wireless terminal while the area is in the appropriate cell.
The wireless terminal according to

appendix

1 or 2, characterized in that

(Supplementary Note 4)
The information processing apparatus further comprises a data processing unit that decodes the broadcast information, extracts information necessary for specifying a condition under which the wireless terminal operates, and notifies the determination unit of the information.
The communication control unit controls the wireless terminal to be in the appropriate cell, and then notifies the data processing unit of the broadcast information acquired while the wireless terminal is in the appropriate cell. ,
Appendix 3. The wireless terminal according to appendix 3.

(Supplementary Note 5)
When the received electric field of the cell before the cell reselection is equal to or less than a predetermined threshold, the determination unit performs the cell reselection by the communication control unit, and places the wireless terminal in such a manner as to locate the appropriate cell. After control, it is not determined whether the second current consumption value is larger than the first current consumption value.
The wireless terminal according to any one of appendices 1 to 4, characterized in that:

(Supplementary Note 6)
The cells targeted for the cell reselection include cells of a plurality of different RATs,
The mobile wireless terminal according to any one of appendices 1 to 5, characterized in that

(Appendix 7)
A control method of a wireless terminal performing wireless communication in a cellular system, comprising:
A communication control step of performing cell reselection to select an appropriate cell found under a predetermined condition while the radio terminal is in a cell, and controlling the radio terminal to be in the appropriate cell; ,
In the communication control step, after the cell reselection is performed and the wireless terminal is controlled to be located in the appropriate cell, the wireless stored in association with each of the conditions under which the wireless terminal operates. The consumption current value indicating the current consumed by the terminal is associated with the condition under which the radio terminal operates in the cell before cell reselection which is the cell in which the radio terminal was located before the cell reselection. Obtaining a first current consumption value which is the current consumption value, and a second current consumption value which is the current consumption value associated with the condition under which the wireless terminal operates in the appropriate cell; A determination step of determining whether the current consumption value of 2 is smaller than the first current consumption value;
If it is determined in the determination step that the second consumption current value is smaller than the first consumption current value, the appropriate cell is located as it is, and the second consumption current value is determined in the determination step. A control step of controlling the wireless terminal to revisit the cell before the cell reselection if it is determined that the current consumption value is not smaller than the first current consumption value;
And a control method characterized by including.

(Supplementary Note 8)
In a wireless terminal performing wireless communication in a cellular system,
A communication control function of performing cell reselection to select an appropriate cell found based on a predetermined condition while the wireless terminal is in a cell, and controlling to locate the appropriate cell;
A data storage function that stores the condition under which the wireless terminal operates and the current consumption value indicating the current consumed by the wireless terminal in association with each other;
After the cell reselection is performed by the communication control function and the radio terminal is controlled to be located in the appropriate cell, the cell in which the radio terminal was located before the cell reselection is performed A consumption current value corresponding to a condition for the wireless terminal to operate in a cell before a certain cell reselection is a first consumption current value, and a consumption current value corresponding to the condition for the wireless terminal to operate in the appropriate cell is A determination function of determining the consumption current value stored in the data storage function as the consumption current value of 2, and determining whether the second consumption current value is smaller than the first consumption current value;
To achieve
The communication control function controls to be in the proper cell as it is when the determination function determines that the second consumption current value is smaller than the first consumption current value, and the determination function Control the wireless terminal to revisit the cell of the cell reselection if it is determined that the second consumption current value is not smaller than the first consumption current value.
A computer readable recording medium characterized in that a program is recorded.

The present invention is based on Japanese Patent Application No. 2012-14908 filed on January 27, 2012. The specification, claims, and whole drawings of Japanese Patent Application No. 2012-14908 are incorporated herein by reference.

The present invention is suitable for optimization of the power consumption state of a portable terminal.

100 Portable wireless terminal 101 Radio unit 102 Communication control unit 103 Control unit 104 Data storage unit 105 Determination unit 106 Data processing unit 200 Network (NW)

Claims

A wireless terminal that performs cellular wireless communication, and
A communication control unit that performs cell reselection to select an appropriate cell found under a predetermined condition while the wireless terminal is in a cell, and controls the wireless terminal to stay in the appropriate cell;
A data storage unit that associates and stores a condition under which the wireless terminal operates and a current consumption value indicating the current consumed by the wireless terminal;
After the communication control unit performs the cell reselection and controls the wireless terminal such that the wireless terminal is located in the appropriate cell, the wireless terminal is a cell that was present before the cell reselection was performed. The current consumption value corresponding to the condition in which the wireless terminal operates in the cell before cell reselection is the first current consumption value, and the current consumption value corresponding to the condition in which the wireless terminal operates in the appropriate cell is the second A determination unit that determines, from the data storage unit, a current consumption value of the second current consumption value, and determines whether the second current consumption value is smaller than the first current consumption value;
Equipped with
When the determination unit determines that the second consumption current value is smaller than the first consumption current value, the communication control unit is as it is in the appropriate cell, and the second consumption current value If it is determined that the current consumption value is not smaller than the first consumption current value, the wireless terminal is controlled to re-visit the cell before the cell reselection,
A wireless terminal characterized by
The communication control unit controls the appropriate cell not to be selected in cell reselection for a predetermined time when the radio terminal is controlled to revisit the cell before the cell reselection after the cell reselection. ,
The wireless terminal according to claim 1, characterized in that:
The communication control unit further acquires broadcast information from a network while the wireless terminal is in a cell.
The determination unit specifies a condition under which the wireless terminal operates in the cell before cell reselection, based on the broadcast information acquired while the wireless terminal is in the cell before the cell reselection. After the communication control unit performs the cell reselection and controls the wireless terminal to locate the appropriate cell, based on the broadcast information acquired by the wireless terminal in the appropriate cell. And identifying the conditions under which the wireless terminal operates in the appropriate cell, and holding the broadcast information acquired by the wireless terminal while the area is in the appropriate cell.
The wireless terminal according to claim 1 or 2, characterized in that:
The information processing apparatus further comprises a data processing unit that decodes the broadcast information, extracts information necessary for specifying a condition under which the wireless terminal operates, and notifies the determination unit of the information.
The communication control unit controls the wireless terminal to be in the appropriate cell, and then notifies the data processing unit of the broadcast information acquired while the wireless terminal is in the appropriate cell. ,
The wireless terminal according to claim 3, characterized in that:
When the received electric field of the cell before the cell reselection is equal to or less than a predetermined threshold, the determination unit performs the cell reselection by the communication control unit, and places the wireless terminal in such a manner as to locate the appropriate cell. After control, it is not determined whether the second current consumption value is larger than the first current consumption value.
The radio | wireless terminal of any one of the Claims 1 thru | or 4 characterized by the above-mentioned.
The cells targeted for the cell reselection include cells of a plurality of different RATs,
The mobile wireless terminal according to any one of claims 1 to 5, characterized in that:
A control method of a wireless terminal performing wireless communication in a cellular system, comprising:
A communication control step of performing cell reselection to select an appropriate cell found under a predetermined condition while the radio terminal is in a cell, and controlling the radio terminal to be in the appropriate cell; ,
In the communication control step, after the cell reselection is performed and the wireless terminal is controlled to be located in the appropriate cell, the wireless stored in association with each of the conditions under which the wireless terminal operates. The consumption current value indicating the current consumed by the terminal is associated with the condition under which the radio terminal operates in the cell before cell reselection which is the cell in which the radio terminal was located before the cell reselection. Obtaining a first current consumption value which is the current consumption value, and a second current consumption value which is the current consumption value associated with the condition under which the wireless terminal operates in the appropriate cell; A determination step of determining whether the current consumption value of 2 is smaller than the first current consumption value;
If it is determined in the determination step that the second consumption current value is smaller than the first consumption current value, the appropriate cell is located as it is, and the second consumption current value is determined in the determination step. A control step of controlling the wireless terminal to revisit the cell before the cell reselection if it is determined that the current consumption value is not smaller than the first current consumption value;
And a control method characterized by including.
In a wireless terminal performing wireless communication in a cellular system,
A communication control function of performing cell reselection to select an appropriate cell found based on a predetermined condition while the wireless terminal is in a cell, and controlling to locate the appropriate cell;
A data storage function that stores the condition under which the wireless terminal operates and the current consumption value indicating the current consumed by the wireless terminal in association with each other;
After the cell reselection is performed by the communication control function and the radio terminal is controlled to be located in the appropriate cell, the cell in which the radio terminal was located before the cell reselection is performed A consumption current value corresponding to a condition for the wireless terminal to operate in a cell before a certain cell reselection is a first consumption current value, and a consumption current value corresponding to the condition for the wireless terminal to operate in the appropriate cell is A determination function of determining the consumption current value stored in the data storage function as the consumption current value of 2, and determining whether the second consumption current value is smaller than the first consumption current value;
To achieve
The communication control function controls to be in the proper cell as it is when the determination function determines that the second consumption current value is smaller than the first consumption current value, and the determination function Control the wireless terminal to revisit the cell of the cell reselection if it is determined that the second consumption current value is not smaller than the first consumption current value.
A computer readable recording medium characterized in that a program is recorded.