JP6530888B2 - User apparatus and frequency selection method - Google Patents

Description

  The present invention relates to a technology for selecting a cell in which a user apparatus is located in a mobile communication system.

  In LTE (including LTE-Advanced), as shown in FIG. 1, the user apparatus UE is managed in two states, an RRC connected state and an IDLE state. The RRC connected state is a state in which a connection is established in RRC, and the user apparatus UE is in a state capable of transmitting and receiving user data. It is desirable that the user apparatus UE having data maintain the RRC connected state in order to transmit and receive data without delay.

  On the other hand, in the IDLE state, a connection is not established in RRC, and when the user apparatus UE transmits and receives user data, it is necessary to first establish a connection with the NW. The user apparatus UE having no data is preferably in the IDLE state from the viewpoint of battery saving and resources.

3GPP TS 36.304 V11.6.0 (2013-12)

  As described above, it is desirable that the user apparatus UE not having data is in the IDLE state, but in the current LTE system, the user apparatus UE in the IDLE state is located in the best cell (the cell with the best quality). When sending, it will connect to the best cell.

  If the user apparatuses UE performing connection are concentrated in a cell of a specific band, there is a possibility that the cell may be congested, which is not preferable, and it is desirable to disperse a plurality of user apparatuses UE in cells of different bands.

  In order to band-disperse the user apparatuses UE in the IDLE state, it is necessary to temporarily connect the user apparatuses UE to the cell in which the user apparatuses UE are located, and then to transition to a band to be distributed by handover (HO). That is, as shown in FIG. 2, the user apparatus UE makes a call (step 1), transitions from IDLE to Active (connected state) (step 2), and then determines band distribution (step 3), and HO (Step 4).

  However, when such steps are taken, user throughput may be reduced because a delay due to inserting a connected state transition procedure or an HO procedure or a delay due to an HO failure occurs.

  The present invention has been made in view of the above, and it is an object of the present invention to provide a technique for performing band distribution of user apparatuses in a mobile communication system.

According to an embodiment of the present invention, there is provided a user equipment for communicating with a base station in a mobile communication system, comprising:
The user apparatus is prioritized by performing cell search when system information including information instructing performing location control for frequency dispersion is received from the base station in the serving cell Detection means for detecting a plurality of frequencies having the same priority among a plurality of frequencies;
As the location control for the frequency dispersion, the user device selects the frequency of the cell to be located from among the plurality of frequencies based on the identification information of the user device and the number of the plurality of frequencies. Selection means to
A user device is provided, characterized in that

  According to the embodiment of the present invention, it is possible to provide a technique for performing band distribution of user apparatuses in a mobile communication system.

It is a figure which shows the transition between the Idle state of RRC, and a Connected state. It is a figure for demonstrating the present subject. FIG. 1 is an overall configuration diagram of a mobile communication system according to an embodiment of the present invention. It is a figure which shows the sequence of the process in 1st Embodiment. It is a figure for demonstrating the conventional cell reselection process. It is a figure for demonstrating the cell reselection process in 1st Embodiment. It is a function block diagram of the user apparatus UE in 1st Embodiment. It is a flowchart which shows operation | movement of the user apparatus UE in 1st Embodiment. It is a function block diagram of the user apparatus UE in 2nd Embodiment. It is a sequence diagram which shows operation | movement of the user apparatus UE in 2nd Embodiment. It is a sequence diagram which shows the flow of the process in 3rd Embodiment. It is a function block diagram of the base station eNB in 3rd Embodiment. It is a flowchart which shows operation | movement of the base station eNB in 3rd Embodiment. It is a function block diagram of the user apparatus UE in 3rd Embodiment. It is a sequence diagram which shows operation | movement of the user apparatus UE in 3rd Embodiment. It is a figure which shows the example of the table which matched the value (Backoff Parameter value) of a back-off timer, and the index.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the following embodiments. For example, although the following embodiment shows an example in which the present invention is applied to an LTE mobile communication system, the present invention can also be applied to mobile communication systems other than LTE. In addition, "LTE" is used in the meaning also including LTE-Advanced.

  In the following description, the term "frequency" is mainly used such that "frequency" is selected when the user apparatus UE performs a cell search or the like. This can be reworded as "band", "carrier frequency", etc.

(Outline of Embodiment, Overall System Configuration)
In the present embodiment, band distribution is performed by causing the user apparatus UE to exist in cells of various frequencies without causing the user apparatus UE to transition to the connected state. That is, by distributing a plurality of user apparatuses UE in the IDLE state into cells of various frequencies, it is possible to avoid the delay associated with the connected state transition procedure and the handover procedure (+ handover failure).

  FIG. 3 shows an entire configuration diagram of a mobile communication system according to the embodiment of the present invention. This entire configuration is common to the first to third embodiments described later. As shown in FIG. 3, the mobile communication system according to the present embodiment includes a base station eNB which forms a cell by a carrier of a predetermined frequency, and a user apparatus UE which is located in the cell and communicates with the base station eNB.

  In the example of FIG. 3, the user apparatus UE is located in the serving cell A of the base station eNB. The serving cell A may be referred to as a connection cell or the like. Further, in FIG. 3, neighboring cells B and C adjacent to the serving cell A are shown. The frequency in these adjacent cells B and C may be the same as or different from the serving cell A. Also. The RATs (eg, LTE, 3G, etc.) in adjacent cells B and C may be the same as or different from serving cell A. The adjacent cell may be referred to as a neighboring cell.

  The first to third embodiments will be described below. In the first embodiment, in the selection of the frequency / RAT in each user apparatus UE, control is introduced such that the frequency / RAT selected by each user apparatus UE is dispersed. In the second embodiment, control is introduced such that the frequency / RAT selected by each user apparatus UE is dispersed when the user apparatus UE makes a call. In the third embodiment, although the user apparatus UE is connected in the serving cell, the control of the base station eNB temporarily rejects the connection without transitioning to the connected state to cause cell reselection to be performed.

  Note that the description “frequency / RAT” is to reselect a cell of a different frequency in the RAT or a RAT cell different from the RAT as viewed from the user equipment UE located in the cell of the RAT. In the following, instead of describing “frequency / RAT”, it is simply described as “frequency”. In this description, it is intended to include the meaning of transition to different frequency cells within a certain RAT and transition to different RATs. Each embodiment will be described below.

First Embodiment
The user apparatus UE in the mobile communication system defined by LTE selects a cell of a frequency with the best quality (highest reception strength) in cell selection performed at power on etc. . In addition, "is located in a cell" synchronizes with the base station eNB by receiving a synchronization signal from the base station eNB of the cell, for example, and receives system information (which may be called broadcast information) ( It is possible to interpret.

  In the present embodiment, the user apparatus UE located in a certain cell performs cell reselection processing and focuses on an operation in which it is located in a cell having a frequency different from the frequency of the cell. . In other words, there are cases where cell reselection involves selecting a cell with a frequency different from that of the serving cell, or selecting another cell with the same frequency as the serving cell, etc. The embodiment focuses on cell reselection to different frequencies.

  The basic processing flow in the present embodiment will be described with reference to FIG. First, as a premise of the operation of FIG. 4, it is assumed that the user apparatus UE is located in the best cell with the largest reception strength selected at the time of cell selection.

  First, the user apparatus UE receives, from the base station eNB, system information including frequencies (generally a plurality) of cells in which the user apparatus UE can be located and priority information (priority) of the respective frequencies (step 11). .

  In step 12, the user apparatus UE performs cell reselection processing. With regard to cell reselection (inter-frequency / inter-RAT cell reselection) transitioning to a cell of different frequency, the user apparatus UE has higher priority than the frequency of the serving cell among the frequencies notified in the system information. Based on priority information, it is necessary to search for a cell of a frequency and perform an operation of serving a new cell when the frequency satisfies a predetermined quality condition (such as reception strength is equal to or higher than a predetermined threshold). Cell reselection operation, but depending on the quality of the current serving cell and the quality of the transition destination, cell reselection to a cell with a priority equal to or lower than the current priority may be performed. .

  In step 12, as a result of cell search for measuring the carrier of each frequency, it is assumed that there are a plurality of frequencies of adjacent cells (a frequency different from the frequency of the connection cell) where the user apparatus UE can be located . Being able to be located means meeting a predetermined quality condition.

  Here, in the prior art, if the priority is the same, a frequency with better quality is selected, but it is not possible to achieve band dispersion. Therefore, in the first embodiment, in step 12, a frequency having an index obtained by taking the mod of the number of frequencies (N) as the identifier of the user apparatus UE is selected as an index from the plurality of frequencies. Stay in the frequency cell.

  The above-mentioned identifier of the user apparatus UE is, for example, a telephone number, IMEI (International Mobile Equipment Identity) or the like, but is not limited thereto.

  Further, the number of frequencies (N) is the number of frequencies of the same priority (a frequency different from the frequency of the connected cell) in which the user apparatus UE can be located. For example, assuming that N is 2, two frequencies are given indexes of 0 and 1, respectively. And since the mod of 2 is 0 or 1, the frequency of 0 or 1 is selected. By selecting the frequency based on the identifier of the user apparatus UE for the frequency of the same priority, the frequencies are selected almost equally among the user apparatuses UE, so band dispersion can be achieved.

  A more specific control example in the first embodiment will be described below.

  For example, as described in Non-Patent Document 1, in LTE, (1) Measurement rules for cell reselection, (2) different frequency cell reselection criteria (E-UTRAN Inter- (3) Frequency and inter-RAT Cell Reselection criteria, (3) Intra-frequency and equal priority inter-frequency Cell Reselection criteria, which are defined in the prior art, The operation is performed according to these rules.

Regarding the above (3), as described in Non-Patent Document 1, in each of adjacent cells (neighbor cells) and connecting cells (serving cells) of the same priority, as shown in FIG. Based on the index (R _s , R _n ), ranking will be performed, and the cell with the highest rank will be selected. In addition, for the adjacent cells (R _n ), it is possible to set an offset (Q offset _frequency ) specific to each _frequency .

  On the other hand, in the present embodiment, (3) the operation of the same priority different frequency cell reselection in the same frequency and the same priority different frequency cell reselection is different from the operation in the prior art. In this embodiment, since there are two types of operations, they will be described as specific example 1 and specific example 2 below.

<Specific example 1>
In the first embodiment, although the parameters to be used are as shown in FIG. 5, only one frequency (carrier) among frequencies (inter-frequencies) having the same priority for each user apparatus UE is Qoffset _frequency = It is assumed that 0, and for the other frequencies, the broadcasted offset value is applied. By setting Qoffset _frequency = 0, the index (R _n ) becomes large, and cells of the relevant frequency can be easily selected.

Then, in the first example, as in the above-described method, a frequency corresponding to a value obtained by taking N mod, which is the number of frequencies of the same priority, is selected for the identifier of the user apparatus UE (for example, IMSI). Do. For example, suppose that there are two frequencies with the same priority, and the index is i (i = 0, 1). In this case, if IMSI mod N = 0, then Qoffset _frequency = 0 for i = 0 frequencies, and if IMSI mod N = 1, then Qoffset _frequency = 0 for i = 1 frequencies. In addition, it is possible to set which frequency to be the order of notification information of the frequency of the adjacent cell in the system information (for example, SIB5) in any case.

<Specific example 2>
In the second specific example, as shown in FIG. 6, new parameters Qoffset and UE are introduced in the calculation of R _n . Qoffset, UE is information notified to the user apparatus UE by system information. When Qoffset and UE are added, R _n becomes large and the frequency is likely to be selected.

  It is the same as that of specific example 1 about which frequency Qoffset other than 0 and UE are applied to. That is, Qoffset and UE are applied to the frequency corresponding to the value obtained by taking N mod, which is the number of frequencies of the same priority, to the identifier of the user apparatus UE (for example, IMSI), and Qoffset for other frequencies. , UE = 0. For example, suppose that there are two frequencies with the same priority, and the index is i (i = 0, 1). In this case, if IMSI mod N = 0, Qoffset and UE are valid for the frequency of i = 0, and if IMSI mod N = 1, Qoffset and UE are valid for the frequency of i = 1. In addition, it is possible to set which frequency to be the order of notification information of the frequency of the adjacent cell in the system information (for example, SIB5) in any case.

<Another Example of the First Embodiment>
Although the examples described so far have been directed to cell reselection, the method of selecting a frequency based on the result of taking N mods for the identifier of the user apparatus UE corresponds to the case of cell selection performed before cell presence. Is also applicable.

  That is, in the prior art, at the time of cell selection, the cell of the best frequency is selected on the basis of quality alone, but this can not achieve band dispersion. Therefore, in the present embodiment, the user apparatus UE sets the number to N when detecting a plurality of frequencies of the available quality at the time of cell selection (these can be regarded as the same priority). In the cell of the frequency corresponding to the result of taking N mods for the identifier of the user apparatus UE. The order of N is arbitrary, and may be, for example, the order of detection or the order of quality.

  Also, in the example of cell reselection described so far, the selection is made to be evenly distributed, such as taking a mod, but the capability of the user apparatus UE, the access class, the reason for transmission (cause The frequency which is located may be selected from a plurality of frequencies with the same priority according to the type and the like. Further, as information replacing the existing priority information, information in which a capability / access class or the like and a frequency to be preferentially selected may be notified by system information.

  For example, since a user apparatus UE (Voice capable UE) having voice communication capability is predicted to perform voice transmission, control can be performed to preferentially select a frequency from the core band. The “core band” is a band serving as a predetermined core and is a band suitable for voice communication. Also, the user apparatus UE (CA capable UE) having the capability of carrier aggregation can be controlled to select the frequency of the band corresponding to the CA. Also, the high priority user equipment UE (eg, Premium User) may be controlled to select a cell of the core band frequency to reduce cell reselection delay. In these controls, for example, the user apparatus UE receives, as system information, information in which the capability / access class etc. and the frequency to be preferentially selected are associated as system information, and based on the information and its own information. It can be done.

  The access class corresponds to the priority of access, and each user apparatus UE generally has any one of 0 to 9 access classes. 11 to 15 are higher priority access classes and are assigned to user apparatuses UE of special applications such as security services.

  In the present embodiment, for example, it is also possible to control that the user apparatuses UE of access classes 0 to 9 stay in the cell of the index frequency obtained by taking N mod in their own access class. N is as described above, and is the number of available frequencies with the same priority in cell reselection, and is the number of available frequencies based on quality in cell selection.

  In addition, it is also possible to control user equipments UE having an access class of 11 to 15 to be present in the core band frequency.

  Also, the user apparatus UE may hold a history of which service (voice, Internet access, etc.) has been transmitted, and may perform frequency selection based on the history in cell selection or cell reselection. For example, since the user apparatus UE that frequently performs voice communication may be voice again next time, the frequency of the core band may be preferentially selected. Frequent voice communication means, for example, the case where the ratio of the number of voice transmissions is equal to or more than a predetermined threshold among the number of transmissions from a predetermined period before to the present.

  Moreover, the user apparatus UE may select the cell of the frequency to which communication was last performed in cell selection. This is based on the fact that if the band distribution in communication is successful, the user devices UE in the area will also be distributed. Also, the user apparatus UE may randomly select one frequency from frequencies whose quality is equal to or higher than a predetermined level, and may be located in a cell of the frequency.

<Device configuration, processing flow example>
FIG. 7 shows a functional configuration of the user apparatus UE in the first embodiment. As shown in FIG. 7, the user apparatus UE according to the present embodiment includes a UL signal transmission unit 101, a DL signal reception unit 102, a control information storage unit 103, and a location control unit 104. The functional configuration shown in FIG. 7 shows a configuration particularly related to the present embodiment, and includes a function for executing an operation defined in LTE as its basic function. The same applies to the other embodiments.

  The UL signal transmission unit 101 transmits a radio signal to the base station eNB. The DL signal reception unit 102 receives a radio signal from the base station eNB. The control information storage unit 103 includes control information (e.g., priority information) acquired from the radio signal received from the base station eNB by the DL signal receiving unit 102, and information preset in the user apparatus UE (e.g., identifier) Is stored.

  As described above, the location control unit 104 performs cell search, performs frequency selection, and the like. For example, based on the result of cell search (the quality of each frequency, etc.) and the priority information stored in control information storage section 103, location control section 104 determines N frequencies of the same priority that can be located. When it detects, the cell of the frequency corresponding to the value which took N mod with respect to the identifier of the user apparatus UE is selected, and it is located.

  FIG. 8 is a diagram showing an example of a process flow performed by the user apparatus UE in the present embodiment. In this example, the user apparatus UE receives, from the base station eNB, a flag instructing whether to perform location control for band distribution as described in the present embodiment, and the flag is ON. It is decided to perform the location control in a certain case.

  The user apparatus UE reads system information of a serving cell (eg, the best cell with the best quality) (step 101), and checks whether a presence control flag is ON (step 102). If it is not ON, the process of location control according to the present embodiment is not performed.

  If the flag of the area control is ON, the user apparatus UE determines whether a cell search for transition to another cell is necessary based on the quality of the frequency of the cell in the area, etc. (step 103). If no cell search is required, the current cell is visited (step 104).

  If cell search is required, cell search and frequency selection are performed (step 105). In step 105, when the user apparatus UE detects a plurality of high-quality same priority frequencies by cell search, the user apparatus UE selects one frequency using, for example, the selection method using the mod described above, and selects the one frequency Stay in the cell of

  The configuration of the user device in the present embodiment is not limited to the above, and may be any configuration that can execute the processing described in the present embodiment. For example, the following configuration may be used.

  That is, the user apparatus according to the present embodiment is a user apparatus that communicates with a base station in the mobile communication system, and includes detection means for detecting a plurality of frequencies with the same priority by performing cell search; And selecting means for selecting the frequency of the cell to which the user equipment should be located based on conditions other than the quality.

  The selection means can select a frequency of a cell to which the user equipment should be located based on identification information of the user equipment and the number of the plurality of frequencies. The selection means may select the frequency of the cell to which the user equipment should be located based on the capability or access class of the user equipment. With such a configuration, it is possible to select a frequency to be located from a plurality of frequencies with the same priority according to information other than the quality.

Second Embodiment
In the first embodiment, cell selection and cell reselection in a state where transmission is not performed have been described. On the other hand, in the second embodiment, when the user apparatus UE makes a call, cell reselection is performed in consideration of factors other than the quality.

  Also in the present embodiment, the priority information is notified to the user apparatus UE for each frequency in the system information as in the first embodiment.

  However, the priority information in the present embodiment is associated with the type of transmission, the access class, the service type, and the like.

  As an example, in the adjacent cell, when the frequencies F1 and F2 exist in the core band and the frequencies F3 and F4 exist in the capacity band, the base station eNB proceeds to the voice service in the order of high priority F1 → The priority information in the order of F 2 → F 3 → F 4 is notified to the user apparatus UE. Since the core band has a frequency lower than that of the capacity band and has a wide coverage, in the case of a voice service requiring coverage, the order is F1 → F2 → F3 → F4.

  Also, for example, in the case of a wide-band required best effort (BE) service (such as Web access), the order may be F3 → F4 → F1 → F2.

  Then, when transmitting, the user apparatus UE identifies the type of transmission (voice, BE data, etc.), and performs cell reselection according to the priority information notified by the system information corresponding to the type. Here, for example, with regard to the identification of the type of voice transmission, the user apparatus UE may identify the voice transmission by detecting that the call button of the telephone is pressed, or may transmit (or receive) in a random access procedure. ) May be identified by information in the message to be identified, or by other methods. In addition, with regard to the best effort service, when it is detected that http data or the like for accessing the Internet is transmitted, it may be detected that the transmission of the best effort service is performed, and transmission is performed by a random access procedure. It may be identified by the information in the message (or received), and may be identified by other methods.

  The user apparatus UE starts a search (measurement) from a high priority frequency, searches in descending order according to the priority until a predetermined quality is obtained, and locates a cell of a frequency for which the predetermined quality is obtained. Make an outgoing call.

  In addition, when a plurality of frequencies with the same priority having a predetermined quality are detected, they may be randomly selected, or, as in the first embodiment, the identifier of the user apparatus UE (phone number, In IMEI), the frequency corresponding to the result of taking mod with the number of detected frequencies (N) may be selected. Furthermore, at the time when the transmission is triggered (represented by SFN, TTI, etc.), the frequency corresponding to the result of taking the mod with the number of frequencies (N) may be selected.

<Device configuration, processing flow example>
FIG. 9 shows a functional configuration of the user apparatus UE in the second embodiment. As shown in FIG. 9, the user apparatus UE according to the present embodiment includes a UL signal transmission unit 201, a DL signal reception unit 202, a control information storage unit 203, a transmission processing unit 204, and a location control unit 205.

  The UL signal transmission unit 201 transmits a radio signal to the base station eNB. The DL signal reception unit 202 receives a radio signal from the base station eNB.

  The control information storage unit 203 is control information (eg, system information) acquired from the radio signal received from the base station eNB by the DL signal reception unit 202, and control information (eg, identifier) set in advance in the user apparatus UE. Is stored.

  The transmission processing unit 204 performs processing of transmitting voice, data, and the like based on, for example, a user operation. When the transmission processing unit 204 detects that the transmission is performed, the location control unit 205 performs cell reselection processing according to the control method described above. For example, it is assumed that the frequencies F1, F2, F3 and F4 of adjacent cells exist, and that priority information in the order of F1 → F2 → F3 → F4 is notified in the order of high priority for voice service. When the location control unit 205 detects that voice transmission is performed by the transmission processing unit 204, it searches in the order of F1 → F2 → F3 → F4 until a frequency of a predetermined quality or more is found, and the predetermined quality or more In the cell of the frequency of.

  FIG. 10 is a diagram showing an example of a process flow performed by the user apparatus UE in the present embodiment. In this example, the user apparatus UE receives, from the base station eNB, a flag instructing whether to perform location control for band distribution as described in the present embodiment, and the flag is ON. It is decided to perform the location control in a certain case.

  The user apparatus UE reads the system information of the serving cell (eg, the best cell with the best quality) (step 201), and checks whether the presence control flag is ON (step 202). If it is not ON, the process of location control according to the present embodiment is not performed.

  If the flag of the area control is ON, the user apparatus UE checks whether or not there is a call (step 203), and when a call is detected, a cell based on priority information corresponding to the type of call etc. A reselection process is performed (step 204). Here, although the search is performed based on the priority information, when the frequency of the adjacent cell satisfying the predetermined quality is not found, the cell is transmitted in the located cell (step 205). In the case of cell transition, transmission is performed after cell transition (step 206).

  The configuration of the user device in the present embodiment is not limited to the above, and may be any configuration that can execute the processing described in the present embodiment. For example, the following configuration may be used.

  That is, the user apparatus according to the present embodiment is a user apparatus that communicates with a base station in a mobile communication system, and the receiving means for receiving the priority for each frequency from the base station, and the user apparatus transmits a call. When performing the cell control, the cell search is performed in the order of the frequency based on the priority corresponding to the type of the transmission, and the location control for placing the user apparatus in the cell of the frequency satisfying the predetermined quality condition detected by the cell search And means.

  The location control means may select the frequency of the cell to which the user equipment should be located based on conditions other than the quality when detecting a plurality of frequencies with the same priority satisfying the predetermined quality condition. it can. With such a configuration, it is possible to locate the frequency suitable for the user's transmission type and to appropriately disperse the band.

Third Embodiment
Next, a third embodiment will be described. In the third embodiment, it is the best cell based on quality that is located by cell selection, and connection is made with the best cell as in the past, but is loosely restricted according to the load status of each cell. Do.

  Also in the present embodiment, the user apparatus UE receives and holds priority information for each frequency from the base station eNB.

  The flow of the entire processing of the present embodiment will be described with reference to the sequence diagram of FIG. The user apparatus UE transmits a connection request (in this example, a random access preamble) to the base station eNB in order to communicate with the base station eNB (step 301).

  The base station eNB that has received the connection request determines whether band distribution is necessary based on the load status of the cell in which the user apparatus UE is located (step 302). For example, the number of connected UEs in the cell, the ratio of UEs performing DRX, or the like can be used as the load status. If the value indicating the load status is equal to or greater than a predetermined threshold value, it is determined that the user apparatus UE is concentrated in the cell, and it is determined that band distribution is necessary.

  If the base station eNB determines that band distribution is necessary, the base station eNB rejects the connection of the user apparatus UE to the cell. In the present embodiment, the back-off timer in the response (in this example, random access response) is set to Infinity, and the response is transmitted (Step 303). The backoff timer is a timer that indicates the time to wait before attempting to connect again when the random access procedure fails in the user apparatus UE. When this value is Infinity, the user apparatus UE once gives up connection to the cell, cancels the random access procedure, and tries connection in descending order of priority with other frequencies satisfying the predetermined quality. The cell of the other frequency may be another cell formed by the same base station eNB as the cell to which connection failed, or may be a cell formed by the adjacent base station eNB. In the above, an example is shown in which the adjacent base station eNB is a cell formed.

  As shown in FIG. 11, the user apparatus UE that has received the response including Infinity searches for another cell, locates the cell (Step 304), and attempts connection in the cell (Step 305). In step 304 of FIG. 11, it is assumed that the priority of the cell to be connected in step 301 is the highest, and the priority of the cell to be connected next is the next.

  In addition, even if the user apparatus UE is notified of infinity, in the case of connection related to transmission by a specific service (for example, voice) or when the user apparatus UE is a high priority user apparatus UE, the user apparatus UE notifies of infinity. You may try to connect to another cell again. However, this is the case in which the cell that has reported infinity is the best cell with the best quality. If the cell is not the best cell, the cell search may be performed to detect the best cell, and to access and connect to the best cell.

  As described above, it may be notified from the base station eNB as system information to which service or UE priority to perform control that does not comply with Infinity, or notification is included in an information element in a random access response. It may be done.

  When it is determined in step 302 of FIG. 11 that the base station eNB does not require band distribution, a response in which a finite value is set to the backoff timer is returned as in the case of the normal random access response.

(Device configuration, processing flow)
FIG. 12 shows a functional configuration diagram of a base station eNB in the present embodiment. As shown in FIG. 12, the base station eNB has a UL signal reception unit 301, a DL signal transmission unit 302, a load determination unit 303, and a UE connection processing unit 304.

  The UL signal reception unit 301 receives a radio signal from the user apparatus UE. The DL signal transmission unit 302 transmits a radio signal to the user apparatus UE. As described above, the load determination unit 303 obtains and holds a value indicating the load status such as the number of connected UEs for each cell, and requires band dispersion by comparing the value indicating the load status with a predetermined threshold. It is determined whether there is any, and if band distribution is required, the UE connection processing unit 304 is notified of that.

  The UE connection processing unit 304 is a functional unit that performs connection processing with the user apparatus UE, and needs load distribution by the load determination unit 303 when receiving a connection request from the user apparatus UE located in a certain cell. When the determination result is obtained, the response storing the Infiniy is returned to the user apparatus UE.

  FIG. 13 is a flowchart showing the operation of the base station eNB in the present embodiment. The UE connection processing unit 304 of the base station eNB receives a connection request from the user apparatus UE (step 401). The load determination unit 402 determines whether or not band distribution is necessary (step 402). If band distribution is not necessary, the UE connection processing unit 304 transmits a response in which the backoff timer is set to a finite value (step 403). ). If band distribution is necessary, the UE connection processing unit 304 transmits a response in which the backoff timer is set to infinity (step 404).

  FIG. 14 shows a functional configuration of the user apparatus UE in the third embodiment. As shown in FIG. 14, the user apparatus UE according to the present embodiment includes a UL signal transmission unit 401, a DL signal reception unit 402, a control information storage unit 403, a connection processing unit 404, and a location control unit 405.

  The UL signal transmission unit 401 transmits a radio signal to the base station eNB. The DL signal reception unit 402 receives a radio signal from the base station eNB. The control information storage unit 403 includes control information (eg, system information) acquired from the radio signal received from the base station eNB by the DL signal reception unit 402, and information (eg, access class) preset in the user apparatus UE. UE priority etc. are stored.

  The connection processing unit 404 performs connection processing (eg, random access procedure etc.) with the base station eNB. The location control unit 405 is a functional unit that performs cell reselection in this embodiment, checks the backoff timer in the response received from the base station eNB by the connection processing unit 404, and if Infinity, the priority information Perform cell reselection based on and perform cell transition. If it is a present value, the normal connection procedure is continued.

  FIG. 15 is a diagram showing an example of a process flow performed by the user apparatus UE in the present embodiment. Also in this example, the user apparatus UE receives, from the base station eNB, a flag instructing whether to perform location control based on the backoff timer as described in the present embodiment, and the flag is ON. It is decided to perform the location control in a certain case.

  The user apparatus UE reads the system information of the serving cell (eg, the best cell with the best quality) (step 501), and checks whether the presence control flag is ON (step 502). If it is not ON, the process of location control according to the present embodiment is not performed.

  When the flag of the location control is ON, the location control unit 405 of the user apparatus UE checks whether the back-off timer included in the response received after the connection request transmission is infinite (step 503). If it is infinite, a cell search of a frequency different from that of the serving cell is performed to locate and connect to a high priority different frequency cell in an available neighbor cell (step 504). If the backoff timer is a finite value, then the normal connection procedure is continued (step 505).

  The value of the backoff timer (Backoff Parameter value) may be associated with the index to notify the index. An example of the correspondence table in that case is shown in FIG. Voice only in the figure indicates that it applies to voice communication only.

  The configuration of the user device in the present embodiment is not limited to the above, and may be any configuration that can execute the processing described in the present embodiment. For example, the following configuration may be used.

  That is, the user apparatus of the present embodiment is a user apparatus that communicates with a base station in the mobile communication system, and transmits a connection request to the base station and receives a response to the connection request from the base station. When the information received by the processing means and the response received by the connection processing means includes predetermined information, a cell search is performed for a frequency different from the frequency of the cell in which the user apparatus is located, and detection is performed by the cell search And location control means for locating the user apparatus in a cell of a frequency satisfying the predetermined quality condition.

  The response is a random access response in a random access procedure, and the predetermined information is information indicating that the backoff timer has an infinite value. With such a configuration, band dispersion is realized.

  Further, the configuration of the base station in the present embodiment is not limited to the above, and may be a configuration that can execute the processing described in this embodiment. For example, the following configuration may be used.

That is, the base station according to the present embodiment is a base station that communicates with a user apparatus in a mobile communication system, and is located in the cell, a load determination unit that determines a load in a cell formed by the base station. When the load determination unit determines that the load of the cell is equal to or more than a predetermined threshold when receiving a connection request from the user apparatus, the cell by the user apparatus is included in a response to the connection request. And connection processing means for transmitting a response including the predetermined information including the predetermined information for refusing connection to the user apparatus. The response is a random access response in a random access procedure, and the predetermined information is information indicating that the backoff timer has an infinite value.
The following configurations are disclosed in the present specification.
(Section 1)
A user apparatus that communicates with a base station in a mobile communication system,
Detection means for detecting a plurality of frequencies with the same priority by performing cell search;
Selection means for selecting, from among the plurality of frequencies, the frequency of the cell to which the user equipment should be located based on conditions other than the quality;
User equipment characterized by including.
(Section 2)
The selection unit selects a frequency of a cell to which the user equipment should be located based on identification information of the user equipment and the number of the plurality of frequencies.
The user apparatus according to claim 1, characterized in that:
(Section 3)
The selection means selects a frequency of a cell to which the user equipment should be located based on the capability or access class of the user equipment
The user apparatus according to claim 1, characterized in that:
(Section 4)
A user apparatus that communicates with a base station in a mobile communication system,
Receiving means for receiving priorities for each frequency from the base station;
When the user equipment makes a call, the cell search is performed in the order of the frequency based on the priority corresponding to the type of the call, and the user equipment is placed in the cell of the frequency satisfying the predetermined quality condition detected by the cell search. Location control means to be located and
User equipment characterized by including.
(Section 5)
The location control means, when detecting a plurality of frequencies with the same priority satisfying a predetermined quality condition, selects the frequency of the cell to which the user apparatus should be located based on conditions other than the quality.
The user apparatus according to claim 4, characterized in that:
(Section 6)
A user apparatus that communicates with a base station in a mobile communication system,
Connection processing means for transmitting a connection request to the base station and receiving a response to the connection request from the base station;
When predetermined information is included in the response received by the connection processing means, a cell search is performed on a frequency different from the frequency of the cell in which the user apparatus is located, and the predetermined value detected by the cell search Location control means for placing the user equipment in a cell of a frequency satisfying the quality condition;
User equipment characterized by including.
(Section 7)
The response is a random access response in a random access procedure, and the predetermined information is information indicating that the backoff timer has an infinite value.
The user apparatus according to claim 6, characterized in that:
(Section 8)
A base station that communicates with a user apparatus in a mobile communication system,
Load determining means for determining a load in a cell formed by the base station;
In the response to the connection request, when the load determination unit determines that the load of the cell is equal to or more than a predetermined threshold when receiving a connection request from the user apparatus located in the cell, Connection processing means for transmitting a response including the predetermined information to the user device including the predetermined information for refusing connection to the cell by the user device;
A base station comprising:
(Section 9)
The response is a random access response in a random access procedure, and the predetermined information is information indicating that the backoff timer has an infinite value.
The base station according to claim 8, characterized in that:
(Section 10)
A frequency selection method executed by a user apparatus that communicates with a base station in a mobile communication system,
A detection step of detecting a plurality of frequencies with the same priority by performing cell search;
Selecting, from among the plurality of frequencies, a frequency of a cell to which the user equipment should be located based on conditions other than quality;
A frequency selection method comprising:

  Although the embodiments of the present invention have been described above, the disclosed invention is not limited to such embodiments, and those skilled in the art should understand various modifications, modifications, alternatives, replacements, and the like. I will. Although specific numerical examples are used to facilitate understanding of the invention, unless otherwise noted, those numerical values are merely examples and any appropriate values may be used. The division of items in the above description is not essential to the present invention, and the items described in two or more items may be used in combination as necessary, and the items described in one item may be used in another item. It may be applied to the matters described in (unless contradictory). The boundaries of the functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operations of multiple functional units may be physically performed by one component, or the operations of one functional unit may be physically performed by multiple components. Although the user equipment and the base station have been described using functional block diagrams for convenience of explanation, such equipment may be implemented in hardware, software or a combination thereof. The software operated by the processor of the user device according to the embodiment of the present invention and the software operated by the processor of the base station are random access memory (RAM), flash memory, read only memory (ROM), EPROM, EEPROM , A register, a hard disk (HDD), a removable disk, a CD-ROM, a database, a server, or any other suitable storage medium. The present invention is not limited to the embodiments described above, and various modifications, alterations, alternatives, and replacements are included in the present invention without departing from the spirit of the present invention.

UE user apparatus eNB base station 101 UL signal transmission unit 102 DL signal reception unit 103 control information storage unit 104 location control unit 201 UL signal transmission unit 202 DL signal reception unit 203 control information storage unit 204 transmission processing unit 205 location control unit 301 UL signal reception unit 302 DL signal transmission unit 303 load determination unit 304 UE connection processing unit 401 UL signal transmission unit 402 DL signal reception unit 403 control information storage unit 404 connection processing unit 405 area control unit

Claims (2)

A user apparatus that communicates with a base station in a mobile communication system,
The user apparatus is prioritized by performing cell search when system information including information instructing performing location control for frequency dispersion is received from the base station in the serving cell Detection means for detecting a plurality of frequencies having the same priority among a plurality of frequencies;
As the location control for the frequency dispersion, the user device selects the frequency of the cell to be located from among the plurality of frequencies based on the identification information of the user device and the number of the plurality of frequencies. Selection means to
User equipment characterized by including. A frequency selection method executed by a user apparatus that communicates with a base station in a mobile communication system,
The user apparatus is prioritized by performing cell search when system information including information instructing performing location control for frequency dispersion is received from the base station in the serving cell Detecting the plurality of frequencies of the same priority among the plurality of frequencies;
As the location control for the frequency dispersion, the user device selects the frequency of the cell to be located from among the plurality of frequencies based on the identification information of the user device and the number of the plurality of frequencies. Selection step to
A frequency selection method comprising:

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