WO2014147796A1

WO2014147796A1 - Connection control apparatus, base station apparatus, communication system and communication method

Info

Publication number: WO2014147796A1
Application number: PCT/JP2013/058127
Authority: WO
Inventors: 裕浜田
Original assignee: 富士通株式会社
Priority date: 2013-03-21
Filing date: 2013-03-21
Publication date: 2014-09-25

Abstract

A connection control apparatus (7) comprises: a load state information reception unit (44) that receives, for each of a plurality of base station apparatuses (3), load state information indicating a load state of the base station apparatus (3) measured therein; a first base station selection unit (49) that selects, as a first base station apparatus (3), any one of the base station apparatuses (3) the load state of which does not satisfy an allowance condition; a mobile station selection unit (50) that selects any one of mobile station apparatuses (2) that is connected to the first base station apparatus (3); a second base station selection unit (50) that selects a second base station apparatus (3), which is other than the first base station apparatus (3), in accordance with a load state of the second base station apparatus (3); and an instruction signal transmission unit (42) that transmits, to the first base station apparatus (3), an instruction signal to switch the connection destination of the mobile station apparatus (2), which is selected by the mobile station selection unit (50), from the first base station apparatus (3) to the second base station apparatus (3).

Description

Connection control apparatus, base station apparatus, communication system, and communication method

The embodiments discussed herein relate to a connection control device, a base station device, a communication system, and a communication method.

In a mobile communication system, the reception strength of RS (Reference Signal) from a base station apparatus is used as a selection criterion for a base station apparatus to which the mobile station apparatus is connected. The mobile station device determines that the radio environment with the base station device that is transmitting the RS with higher reception strength is better, and the reception strength is stronger from the base station device that is the transmission source of the RS with lower reception strength. Handover is performed to change the connection destination to the base station apparatus that is the RS transmission source.

As a related technique, a handoff control in a wireless communication system that includes a wireless control station, a wireless base station, and a plurality of wireless terminals, and performs handoff control for switching a wireless terminal belonging to a certain wireless base station to belong to another wireless base station A method is known (see, for example, Patent Document 1). In this method, when one or a plurality of wireless terminals move from a communicating first zone to another second zone, communication with the second zone is made possible. A step of obtaining data rate information indicating a requested data rate corresponding to each wireless terminal based on a data rate request signal for notifying a station, an average throughput of each wireless terminal before handoff, and a handoff request destination zone Estimating estimated throughput after handoff of each wireless terminal based on the step of obtaining the number of handoff requests, the number of wireless terminal connections in the handoff request destination zone, and the ratio between the data rate information of each wireless terminal and the number of wireless terminal connections Each of which represents the degree of change between the estimated throughput after handoff and the average throughput of each wireless terminal before handoff. A step of calculating an estimated throughput ratio after the handoff of the terminal and a wireless terminal having an estimated throughput ratio equal to or less than a predetermined threshold based on the estimated throughput ratio obtained, the handoff is forgotten, while the estimated throughput ratio is less than the predetermined threshold For a large wireless terminal, performing handoff for the largest wireless terminal among the wireless terminals that have made a handoff request.

JP 2006-050281 A

In the conventional handover, the load state of the base station apparatus that is performing communication and the base station apparatus that is the connection change destination is not considered. For this reason, the connection destination of the mobile station apparatus that has been comfortably communicating with the base station apparatus with a relatively low load is changed to a base station apparatus with a relatively high load, resulting in a decrease in communication throughput.

Even if the throughput of a mobile station apparatus communicating with a relatively high load base station is expected to be improved by changing the connection destination to a relatively low load base station apparatus, the throughput is relatively high. In some cases, connection to the base station apparatus of the load was continued.

An apparatus or method disclosed in the present specification is intended to change a base station apparatus connected to a mobile station connected to a base station apparatus having a relatively high load to a base station apparatus having a relatively low load. And

According to one aspect of the device, a connection control device is provided. The connection control device includes, for each of a plurality of base station devices, a load state information receiving unit that receives load state information indicating a load state of the base station device measured by the base station device, and a base in a load state that does not satisfy the allowable condition A first base station selection unit that selects a station device as a first base station device, a mobile station selection unit that selects any of the mobile station devices connected to the first base station device, and a first base station device other than the first base station device A second base station selection unit that selects two base station devices according to the load state of the second base station device, and a connection destination of any of the mobile station devices selected by the mobile station selection unit is the first base station device An instruction signal transmission unit for transmitting to the first base station apparatus an instruction signal to be changed from the first base station apparatus to the second base station apparatus.

According to another aspect of the apparatus, a base station apparatus is provided. The base station device is a load state measurement unit that measures the load state of the base station device, and a base station device that is measured by a mobile station device connected to the base station device and other base station devices than the above base station device. Radio quality information receiving unit for receiving radio quality information from a mobile station device, load state information transmitting unit for transmitting radio quality information to a predetermined information processing device together with load information indicating a load state, load information and radio quality information A designation signal receiving unit that receives a designation signal that designates one of the mobile station apparatuses connected to the base station apparatus and any of the other base station apparatuses, transmitted by a predetermined information processing apparatus in response to A connection destination changing unit is provided that changes the connection destination of the mobile station device to be designated from the base station device to the base station device designated by the designation signal.

According to the apparatus or method disclosed in the present specification, a base station apparatus connected to a mobile station connected to a base station apparatus having a relatively high load is changed to a base station apparatus having a relatively low load. Is possible.

The objects and advantages of the invention will be realized and attained by means of the elements and combinations shown in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

It is explanatory drawing of the structural example of a communication system. It is explanatory drawing of the example of arrangement | positioning of a base station apparatus and a user apparatus, and the example of a connection used for description of this specification. It is a function block diagram of an example of a user apparatus. It is explanatory drawing of an example of a measurement report. It is a function block diagram of an example of a base station apparatus. It is explanatory drawing of an example of the throughput measured with a base station apparatus. It is explanatory drawing of an example of load status information. It is a functional block diagram of an example of a load condition analyzer. It is explanatory drawing of an example of a load condition list | wrist. It is explanatory drawing of an example of a terminal status list. It is explanatory drawing of an example of operation | movement of a load condition analyzer. It is explanatory drawing of an example of terminal extraction operation | movement. It is explanatory drawing of a handover operation. It is a hardware block diagram of an example of a user apparatus. It is a hardware block diagram of an example of a base station apparatus. It is a hardware block diagram of an example of a load condition analyzer.

<1. Configuration of communication system>
Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of a configuration example of a communication system. In the following description, an example in which the communication system 1 is a system conforming to LTE (Long term Evolution) defined in 3GPP (3rd Generation Partnership Project) standard is used. However, this illustration is not intended that the communication system described in this specification is limited to a communication system that conforms to LTE. The communication system described in this specification can be widely applied to a mobile communication system in which a mobile station apparatus performs handover between base station apparatuses.

The communication system 1 includes a user device 2 as a mobile station device, a base station device 3, an MME (Mobility Management Entity) 4, and an SGW (Serving Gateway) 5. The communication system 1 also includes an EMS (Element Management Management) / NMS (Network Management System) 6 and a load state analysis device 7. In the following description and accompanying drawings, a base station apparatus may be referred to as a “base station”.

User device 2 is a wireless communication device used by a user who uses a mobile communication service by communication system 1. The user device 2 may be, for example, a mobile phone or an information mobile terminal device. The user device 2 can transmit and receive data signals to and from the operator network and the public network of the communication system 1 via wireless communication with the base station 3.

The base station 3 is a wireless communication device that performs wireless communication with the user device 2 by wireless connection. The base station 3 forms one or a plurality of wireless communication areas called cells, and is used for voice communication services and data communication services used by the user apparatuses 2 by performing wireless communication with the user apparatuses 2 located in the cell. The

The MME 4 is connected to the core network 8 and performs access control of the user device 2, control of paging processing for the user device 2, user authentication, and the like. The SGW 5 connects the U plane between the radio access network and the core network 8, and performs routing and transfer of user packets.

The base station 3, the MME 4 and the SGW 5 are connected to the monitoring control network 9, and the operation state is managed by the EMS / NMS 6. The EMS / NMS 6 performs life-and-death monitoring of the base station 3, MME 4, and SGW 5, detection of traffic faults in the core network 8, and security maintenance.

The load state analyzer 7 is provided in the monitoring control network 9 and connected to the base station 3. Based on the load state of the base station 3 on the communication system 1, change control of the base station 3 to which the user apparatus 2 is connected is performed. The load state analyzer 7 may be mounted on the same hardware device as the EMS / NMS 6 as a part of the EMS / NMS 6. Moreover, the load state analyzer 7 may be mounted on the same hardware device as the MME 4 or SGW 5 as a part of the MME 4 or SGW 5.

FIG. 2 is an explanatory diagram of an arrangement example and a connection example of the base station 3 and the user apparatus 2 used in the following description. eNB1 is a macro cell base station that covers a relatively wide area, which is an example of the base station 3. eNBs 2 to 4 indicate small cell base stations that cover a relatively narrow area, which is an example of the base station 3. Reference symbols C1 to C4 indicate radio areas or cells formed by the base stations eNB1 to eNB4.

Ue1 to ue5 indicate the user apparatus 2 in communication. It is assumed that the user apparatuses ue1 and ue5 are connected to the base station eNB4 and the user apparatus ue2 is connected to the base station eNB2 to perform data communication. Further, it is assumed that the user apparatus ue3 is connected to the base station eNB1 and the user apparatus ue4 is connected to the base station eNB3 to perform data communication. The base stations eNB1 to eNB4 are connected to the load state analyzer 7.

<2. Configuration of user device>
Next, functions of each component of the mobile communication system 1 will be described. FIG. 3 is a functional configuration diagram of an example of the user device 2. The user device 2 includes a control unit 10, a wireless communication unit 11, and a signal processing unit 12. The control unit 10 controls the operation of the user device 2. The control unit 10 includes a measurement report transmission unit 15 and a handover processing unit 16 which will be described later. In the following description and accompanying drawings, handover may be referred to as “HO”.

The wireless communication unit 11 performs digital / analog conversion, analog / digital conversion, amplification, frequency conversion and the like of control signals and user traffic wireless signals transmitted and received between the user apparatus 2 and the base station 3. The signal processing unit 12 performs an encoding process, a decoding process, a modulation process, a demodulation process, and the like that are transmitted and received between the user apparatus 2 and the base station 3. The signal processing unit 12 includes a wireless measurement unit 13 and a retransmission control unit 14.

The wireless measurement unit 13 measures the surrounding wireless environment. For example, the wireless measurement unit 13 measures the wireless quality with the connected base station 3. Further, the wireless measurement unit 13 measures the wireless quality between the base station 3 other than the connected base station 3. For example, the radio measurement unit 13 may measure the signal strength of the received signal as radio quality. For example, the radio measurement unit 13 may measure the RS intensity transmitted from the base station as the radio quality. Radio quality may be measured by other methods.

The retransmission control unit 14 determines success or failure of decoding of the received signal from the base station 3, and returns a delivery confirmation signal corresponding to the determination result to the base station 3. For example, the retransmission control unit 14 returns an acknowledgment signal (ACK: ACKnowledgement) as a delivery confirmation signal to the base station 3 when the reception signal from the base station 3 is successfully decoded. The retransmission control unit 14 returns a negative acknowledgment signal (NACK: Negative ACKnowledgement) as a delivery confirmation signal to the base station 3 when decoding of the received signal from the base station 3 fails.

The measurement report transmission unit 15 transmits a measurement report (MR: “Measurement Report”) indicating a measurement result by the wireless measurement unit 13 to the base station 3 when a certain period or a predetermined condition is met. For example, the measurement report transmission unit 15 may transmit a measurement report when a new base station that can be connected with sufficient radio quality is detected. The measurement report serves to notify the base station 3 of the candidates for the base station 3 to which the user apparatus 2 can be connected and the radio quality between the candidate and the user apparatus 2.

FIG. 4 is an explanatory diagram of an example of a measurement report. For example, the measurement report may include information elements “UserID” and “radio state determination result”. The information element “UserID” is an identifier of the user apparatus 2 that is the transmission source. The example of the measurement report in FIG. 4 is a measurement report transmitted by the user apparatus ue1.

The information element “radio state determination result” indicates the wireless quality from the base station 3 measured by the user apparatus 2 that is the transmission source. The radio quality may be indicated by the signal strength of the received signal, for example. In the measurement report example of FIG. 4, the signal strengths of the received signals received by the user apparatus ue1 from the base stations eNB4, eNB1, and eNB2 are x [dB], y [dB], and z [dB], respectively.

In the HO processing, the HO processing unit 16 receives the radio bearer reconfiguration request transmitted from the connected base station 3, and executes the HO processing to the HO destination base station in response to the radio bearer reconfiguration request. To do.

<3. Base station configuration>
FIG. 5 is a functional configuration diagram of an example of the base station 3. The base station 3 includes a control unit 20, a wireless communication unit 21, a signal processing unit 22, and an interface unit 23. In the following description and accompanying drawings, the interface may be referred to as “IF”.

The control unit 20 controls the operation of the base station 3. The control unit 20 includes a measurement report receiving unit 26, a storage unit 27, a load state information transmitting unit 28, a connection change instruction receiving unit 29, and a HO processing unit 30, which will be described later.

The wireless communication unit 21 performs digital / analog conversion, analog / digital conversion, amplification, frequency conversion, and the like of control signals and user traffic wireless signals transmitted and received between the user apparatus 2 and the base station 3. The signal processing unit 22 performs an encoding process, a decoding process, a modulation process, a demodulation process, and the like that are transmitted and received between the user apparatus 2 and the base station 3. The signal processing unit 22 includes a retransmission control unit 24 and a throughput measurement unit 25.

The retransmission control unit 24 performs retransmission control of a signal transmitted from the base station 3 to the user device 2 in accordance with a delivery confirmation signal transmitted from the user device 2. For example, the retransmission control unit 24 may perform retransmission control according to ARQ (automatic retransmission request: Automatic repeat-request) or HARQ (Hybrid ARQ).

The throughput measuring unit 25 measures the throughput of the signal transmitted from the base station 3 to the user apparatus 2. The throughput measurement unit 25 may measure, for example, an average throughput Tave that is a time average of throughput for each user device 2 and an effective throughput Teff for each user device 2. Further, the throughput measuring unit 25 may measure, for example, an overall throughput Tall that is a time average of the total throughput of the entire user apparatus 2 connected to the base station 3.

For example, the throughput measuring unit 25 may calculate a ratio (D0 / p0) obtained by dividing the transmission data amount D0 in the predetermined period p0 by the predetermined period p0 as the average throughput Tave. For example, the throughput measurement unit 25 calculates the effective throughput by dividing the ratio (D1 / p1) obtained by dividing the data amount D1 of the initial data obtained by removing the retransmission data from the transmission data during the predetermined period p0 by the transmission period p1 of the initial data and the retransmission data. It may be calculated as Teff. For example, the throughput measuring unit 25 may calculate the ratio (D2 / p0) obtained by dividing the total data amount D2 transmitted by all the connected user apparatuses 2 during the predetermined period p0 by the predetermined period p0 as the total throughput Tall. .

In order to calculate the effective throughput Teff, the throughput measuring unit 25 may measure the throughput with a functional unit of the base station 3 that performs retransmission control of transmission data from the base station 3 to the user apparatus 2. For example, when the communication system 1 is an LTE-compliant system, the throughput measuring unit 25 may measure the throughput in an RLC layer in which an RLC (Radio Link Control) protocol that terminates ARQ is executed.

In the RLC layer, RLC_PDU (RLC Protocol Data Unit) is accumulated in the transmission buffer, and transmission timing arrives at a certain transmission cycle T. The RLC_PDU is transmitted when data exists in the buffer at the transmission timing.

For example, the throughput measurement unit 25 uses a ratio (Vall / (N × T)) obtained by dividing all the data amounts of RLC_PDUs transmitted during a predetermined number N of transmission cycles T by a period N × T as an average throughput Tave. It may be calculated.

For example, the throughput measuring unit 25 may calculate a data amount (Vall-Vre) that does not include the retransmission data amount Vre among the data amount Val of the RLC_PDU transmitted during the transmission cycle T of the predetermined number N. The throughput measuring unit 25 divides the data amount (Vall−Vre) by the product of the actual number of transmissions Neff of the RLC_PDU in the period N × T, the period T, and the product ((Vall−Vre) / (N × T)). May be calculated as the effective throughput Teff.

For example, the throughput measuring unit 25 may calculate, as the total throughput Tall, a ratio obtained by dividing the total amount of RLC_PDU data transmitted by all user apparatuses during a predetermined number N of transmission cycles T by a period N × T.

FIG. 6 is an explanatory diagram of an example of the throughput measured by the base station 3. For example, in FIG. 2, the base station eNB4 communicates with the user apparatuses ue1 and ue5. The average throughput Tave and effective throughput Teff of the user apparatus ue1 are 6 Mbps and 2 Mbps, respectively. The average throughput Tave and the effective throughput Teff of the user apparatus ue5 are 9 Mbps and 10 Mbps, respectively. The total throughput Tall in the base station eNB4 is 15 Mbps, which is obtained by adding the average throughput 6 Mbps of the user apparatus ue1 and the average throughput 9 Mbps of the user apparatus ue5.

The throughput Tave, Teff, and Tall measured by the throughput measuring unit 25 are added with the identifier of the user device 2 and temporarily stored in the storage unit 27 as throughput information.

The IF unit 23 is an interface for connecting to a host device such as the MME 4 or SGW 5, another base station 3, and a load state analysis device via a fixed communication line.

The measurement report receiving unit 26 of the control unit 20 receives the measurement report transmitted from the user device 2. The load state information transmission unit 28 generates load state information in which the throughput information measured for the user device 2 is added to the wireless quality measurement result included in the measurement report, and transmits the load state information to the load state analysis device 7. .

FIG. 7 is an explanatory diagram of an example of load state information. The load state information includes information elements “UserID”, “average throughput”, “effective throughput”, “total throughput”, “connected base station”, and “candidate base station n” (n is a natural number) included in the throughput information. May be included. The information element “connected base station” is the radio quality between the base station 3 and the user apparatus 2 to which the user apparatus 2 is connected. The information element “candidate base station n” is the radio quality between the candidate of the base station 3 to which the user apparatus 2 can be connected and the user apparatus 2.

The connection change instruction receiving unit 29 receives a connection change instruction transmitted by the load state analyzer 7 in response to receiving the load state information. The connection change instruction is an instruction to change the base station 3 to which the specific user apparatus 2 is connected. The connection change instruction includes designation of the user device 2 to be changed in connection destination and the base station 3 as the connection change destination.

In response to the connection change instruction, the HO processing unit 30 executes a procedure for handing over the user apparatus 2 specified by the connection change instruction to the base station 3 specified by the connection change instruction.

The throughput measuring unit 25, the measurement report receiving unit 26, and the HO processing unit 30 are examples of a load state measuring unit, a wireless quality information receiving unit, and a connection destination changing unit, respectively. The connection change instruction receiving unit 29 is an example of a designation signal receiving unit and an instruction signal receiving unit.

<4. Configuration of load state analyzer>
FIG. 8 is a functional configuration diagram of an example of the load state analysis device 7. The load state analysis device 7 includes a state information acquisition unit 40, an analysis unit 41, a connection change instruction transmission unit 42, and an IF unit 43.

The status information acquisition unit 40 receives the load status information transmitted from the plurality of base stations 3 connected to the load status analysis device 7, thereby obtaining information on the load status of each base station 3 and the status of the user device 2. Get information about. The state information acquisition unit 40 includes a load state information reception unit 44, a state list generation unit 45, and a storage unit 46.

The load state information receiving unit 44 receives load state information transmitted from a plurality of base stations 3 connected to the load state analyzer 7. The state list generation unit 45 generates a load state list 47 indicating the load state for each base station 3 based on the load state information. The state list generation unit 45 stores the generated load state list 47 in the storage unit 46.

FIG. 9 is an explanatory diagram of an example of the load state list 47. The load state list 47 may be, for example, a list of overall throughputs Tall of a plurality of base stations 3 connected to the load state analysis device 7. The load state list 47 may include information elements “base station” and “overall throughput”. The information element “base station” is an identifier of the base station 3, and the information element “total throughput” is the total throughput Tall of each base station 3. For example, in the example of FIG. 9, the total throughputs Tall of the base stations eNB1 to eNB4 are 13 Mbps, 2 Mbps, 2 Mbps, and 15 Mbps, respectively.

The state list generation unit 45 generates a terminal state list 48 indicating the state of the user device 2 connected to the base station 3 connected to the load state analysis device 7 based on the load state information. The state list generation unit 45 stores the generated terminal state list 48 in the storage unit 46.

FIG. 10 is an explanatory diagram of an example of the terminal state list 48. The terminal status list 48 may be a list of average throughput Tave, effective throughput Teff, radio quality with the connected base station 3, and radio quality with the candidate base station 3 to which the user apparatus 2 can be connected. The terminal state list 48 may include information elements “UserID”, “average throughput”, “effective throughput”, “connected base station”, and “candidate base station n” (n is a natural number).

The information element “average throughput” is the average throughput Tave of the user apparatus 2, and the information element “effective throughput” is the effective throughput Teff of the user apparatus 2.

The information element “connected base station” is the wireless quality between the base station 3 and the user apparatus 2 to which the user apparatus 2 is connected. The information element “candidate base station n” is the radio quality between the candidate of the base station 3 to which the user apparatus 2 can be connected and the user apparatus 2.

The analysis unit 41 determines the user device 2 to change the connection destination base station 3 based on the load state information of the base station 3 acquired by the state information acquisition unit 40 and the state information of the user device 2. For example, the analysis unit 41 determines the user apparatus 2 that changes the connection destination base station 3 based on the load state list 47 and the terminal state list 48.

The analysis unit 41 includes a load monitoring unit 49 and a terminal extraction unit 50. The load monitoring unit 49 detects a base station 3 whose load exceeds a predetermined threshold value K0 as a high-load base station. For example, the load monitoring unit 49 refers to the load state list 47 and detects the base station 3 whose total throughput Tall exceeds the threshold value K0. The load monitoring unit 49 notifies the terminal extraction unit 50 of the detected base station 3.

For example, assume that the threshold value K0 is set to 14 Mbps in this embodiment. In the load state of the base station 3 in the example of FIG. 9, the base station eNB4 whose total throughput Tall is 15 Mbps is detected.

When the terminal monitoring unit 50 is notified of the base station 3 whose load exceeds the predetermined threshold value K0 from the load monitoring unit 49, the terminal extracting unit 50 determines the base station 3 to be connected based on the state of the user device 2 connected to the base station 3. The user device 2 to be changed is extracted. For example, the terminal extraction unit 50 determines whether the state of the user apparatus 2 connected to the base station 3 satisfies a predetermined determination condition, and extracts the user apparatus 2 that satisfies the predetermined determination condition.

For example, the terminal extraction unit 50 may refer to the terminal state list 48 to determine whether or not the state of the user device 2 satisfies a predetermined determination condition. Examples of the predetermined determination conditions are shown below. The terminal extraction unit 50 may extract a user apparatus 2 that changes the connection destination base station 3 by combining a part or all of the following conditions (1) to (5) with logical product and logical sum.

(1) If the user device 2 is communicating with the base station 3 notified from the load monitoring unit 49, the user device 2 is extracted. The user apparatus 2 is not extracted unless it is communicating with the base station 3 notified from the load monitoring unit 49.

(2) If there is a candidate for the base station 3 to which the user apparatus 2 can be connected, the user apparatus 2 is extracted. If there is no connectable base station 3 candidate, this user apparatus 2 is not extracted.

(3) If the total of the total throughput Tall of the candidate base station 3 to which the user apparatus 2 can be connected and the average throughput Tave of the user apparatus 2 is equal to or less than the threshold value K1, the user apparatus 2 is extracted. If the total is larger than the threshold value K1, the user device 2 is not extracted. By not extracting the user device 2 when the total is relatively large, when the connection destination of the user device 2 is changed to this candidate, it is possible to avoid that the overall throughput of this candidate becomes excessive.

(4) If the average throughput Tave of the user device 2 is equal to or greater than the threshold value K2, the user device 2 is extracted. When the average throughput Tave is less than the threshold value K2, the user device 2 is not extracted. By not extracting the user apparatus 2 having a relatively small average throughput Tave, it is possible to avoid frequent changes in the connection destination of the user apparatus 2 that has little influence on the load on the base station 3.

(5) If the ratio (Teff / Tave) obtained by dividing the effective throughput of the user device 2 by the average throughput is equal to or less than the threshold value K3, the user device 2 is extracted. When the ratio (Teff / Tave) is larger than the threshold value K3, the user device 2 is not extracted. By not extracting the user equipment 2 having a relatively large ratio (Teff / Tave), carelessly changing the connection destination of the user equipment 2 that is expected to have high effective throughput and high wireless quality with the connected base station 3 It is avoidable to change to.

Further, the terminal extraction unit 50 selects any one of the candidates for the base station 3 to which the user device 2 to be extracted can be connected as the connection change destination base station 3. For example, the terminal extraction unit 50 selects a candidate satisfying the condition (3) as the connection change destination base station 3. That is, the terminal extraction unit 50 selects this candidate as the connection change destination base station 3 when the sum of a certain candidate overall throughput Tall and the extracted average throughput Tave of the user apparatus 2 is equal to or less than the threshold K1.

The terminal extraction unit 50 notifies the connection change instruction transmission unit 42 of the extracted user device 2, the base station 3 to which the user device 2 is connected, and the connection change destination base station 3.

The connection change instruction transmission unit 42 transmits a connection change instruction for designating the user device 2 and the connection change destination base station 3 notified from the terminal extraction unit 50 to the base station 3 to which the user device 2 is connected.

The IF unit 43 is an interface for connecting to the base station 3 via a fixed communication line.

The load monitoring unit 49 and the connection change instruction transmitting unit 42 are examples of the first base station selecting unit and the instruction signal transmitting unit, respectively. The terminal extraction unit 50 is an example of a mobile station selection unit and a second base station selection unit.

<5. Operation explanation>
Subsequently, the changing operation of the connection destination base station 3 in the present embodiment will be described. FIG. 11 is an explanatory diagram of an example of the operation of the load state analysis device 7. In operation AA, the load state information receiving unit 44 receives load state information transmitted from a plurality of base stations 3 connected to the load state analyzer 7.

In operation AB, the state list generation unit 45 generates a load state list 47 based on the load state information. In operation AC, the state list generation unit 45 generates a terminal state list 48 based on the load state information.

In operation AD, the load monitoring unit 49 detects the base station 3 in which the overall throughput Tall exceeds the threshold value K0. The load monitoring unit 49 notifies the terminal extraction unit 50 of the base station 3 whose overall throughput Tall exceeds the threshold value K0. In the example of the load state of the base station 3 and the state of the user apparatus 2 illustrated in FIGS. 9 and 10, the load monitoring unit 49 detects the base station eNB4 and notifies the terminal extraction unit 50 of it.

In operation AE, the terminal extraction unit 50 performs a terminal extraction operation for extracting the user device 2 that changes the connection destination base station 3.

FIG. 12 is an explanatory diagram of an example of the terminal extraction operation. In FIG. 12, the user apparatus and the base station are denoted as “UE” and “eNB”, respectively. Assume that the threshold values K1, K2, and K3 are set to 10 Mbps, 3 Mbps, and 1, respectively.

In operation BA, the terminal extraction unit 50 selects any user device 2 registered in the terminal state list 48. In operation BB, the terminal extraction unit 50 determines whether the selected user device 2 is communicating with the base station notified from the load monitoring unit 49. When the selected user device 2 is communicating with the base station notified from the load monitoring unit 49 (operation BB: Y), the operation proceeds to operation BC. When the selected user apparatus 2 is not communicating with the base station notified from the load monitoring unit 49 (operation BB: N), the operation returns to operation BA.

In the example illustrated in FIGS. 9 and 10, the user apparatuses 2 that are communicating with the base station eNB4 are the user apparatuses ue1 and ue5. Therefore, when the user device 2 being selected is not the user devices ue1 and ue5, the terminal extraction unit 50 does not extract the user device 2 being selected.

In operation BC, the terminal extraction unit 50 determines whether there is a candidate for the base station 3 to which the selected user apparatus 2 can be connected. If there is a candidate (operation BC: Y), the operation proceeds to operation BD. If there is no candidate (operation BC: N), the operation returns to operation BA and the selected user device 2 is not extracted.

In the example illustrated in FIGS. 9 and 10, when the user apparatus 2 being selected is the user apparatus ue1, the operation proceeds to operation BD because the user apparatus ue1 includes the candidate base stations eNB1 and eNB2. When the selected user apparatus 2 is the user apparatus ue5, the operation proceeds to operation BD because the candidate base station eNB1 exists in the user apparatus ue1.

In operation BD, the terminal extraction unit 50 determines whether or not the sum of the total throughput Tall of the candidates for the base station 3 to which the user apparatus 2 can be connected and the average throughput Tave of the user apparatus 2 is equal to or less than the threshold value K1. When the total is equal to or less than the threshold value K1 (operation BD: Y), the operation proceeds to operation BE. When the sum is larger than the threshold value K1 (operation BD: N), the operation returns to operation BA and the selected user device 2 is not extracted.

In the example shown in FIGS. 9 and 10, when the user apparatus 2 being selected is the user apparatus ue1, the total of the average throughput 6 Mbps of the user apparatus ue1 and the total throughput 2 Mbps of the candidate base station eNB2 is 8 Mbps. Since the total 8 Mbps is equal to or less than the threshold value K1 (10 Mbps), the terminal extraction unit 50 does not congest the candidate base station eNB2 even if the connection destination of the user apparatus ue1 is changed to the candidate base station eNB2. For this reason, the terminal extraction unit 50 leaves the user device ue1 as a user device candidate for changing the connection destination base station 3. Further, the terminal extraction unit 50 leaves the base station eNB2 as a connection destination candidate for the user apparatus ue1.

The total 19 Mbps of the average throughput 6 Mbps of the user apparatus ue1 and the total throughput 13 Mbps of the candidate base station eNB1 exceeds the threshold value K1 (10 Mbps). For this reason, the terminal extraction unit 50 removes the base station eNB1 as a connection destination candidate of the user apparatus ue1.

The total 22 Mbps of the average throughput 9 Mbps of the user apparatus ue5 and the total throughput 13 Mbps of the candidate base station eNB1 exceeds the threshold value K1 (10 Mbps). For this reason, the terminal extraction unit 50 removes the user apparatus ue5 as a user apparatus candidate for changing the connection destination base station 3.

In operation BE, the terminal extraction unit 50 determines whether or not the average throughput Tave of the selected user device 2 is equal to or greater than the threshold value K2. If Tave is greater than or equal to threshold value K2 (operation BE: Y), the operation proceeds to operation BF. When Tave is less than the threshold value K2 (operation BE: N), the operation returns to operation BA and the selected user device 2 is not extracted.

9 and FIG. 10, when the user apparatus 2 being selected is the user apparatus ue1, the average throughput 6 Mbps of the user apparatus ue1 is equal to or higher than the threshold K2 (3 Mbps). Therefore, the terminal extraction unit 50 leaves the user device ue1 as a user device candidate for changing the connection destination base station 3. The congestion of the base station eNB4 is expected to be changed by changing the connection destination of the user apparatus ue1 from the currently connected base station eNB4 to another base station.

In operation BF, the terminal extraction unit 50 determines whether or not a ratio (Teff / Tave) obtained by dividing the effective throughput of the selected user apparatus 2 by the average throughput is equal to or less than the threshold K3. When the ratio (Teff / Tave) is equal to or less than the threshold value K3 (operation BF: Y), the operation proceeds to operation BG. When the ratio (Teff / Tave) is larger than the threshold value K3 (operation BF: N), the operation returns to operation BA and the selected user device 2 is not extracted.

In the example illustrated in FIGS. 9 and 10, when the currently selected user apparatus 2 is the user apparatus ue1, the ratio 1/3 obtained by dividing the effective throughput 2 Mbps of the user apparatus ue1 by the average throughput 6 Mbps is the value “1” of the threshold K3. Smaller than. Therefore, the terminal extraction unit 50 leaves the user device ue1 as a user device candidate for changing the connection destination base station 3. When the ratio (Teff / Tave) between the effective throughput and the average throughput is relatively small, it is expected that the communication efficiency between the user apparatus ue1 and the base station eNB4 is relatively low and the radio quality is relatively poor.

In operation BG, the terminal extraction unit 50 extracts the user device 2 remaining as a user device candidate for changing the connection destination base station 3 in the determination of operations BB to BF. In addition, the base station 3 remaining in the determination of the operation BD as the connection change destination candidate of the extracted user apparatus 2 is selected as the connection change destination.

In the example shown in FIGS. 9 and 10, the user device ue1 is extracted. Also, the base station eNB2 is selected as the connection change destination of the user apparatus ue1. By changing the connection destination of the user apparatus ue1 from the base station eNB4 to the base station eNB2, it is expected that the congestion of the base station eNB4 that is the source of the change will be eliminated. Further, since the overall throughput of the base station eNB2 expected after the change is smaller than the overall throughput of the base station eNB4 before the change of the connection destination, the user apparatus ue1 can be connected to the base station eNB2 having a smaller load. . As a result, an improvement in communication throughput of the user apparatus ue1 can be expected. The threshold value K1 may be set smaller than the value obtained by subtracting the threshold value K2 from the threshold value K0 so that the overall throughput of the candidate does not exceed the threshold value K0 by changing the connection destination.

Refer to FIG. In operation AF, the connection change instruction transmission unit 42 transmits a connection change instruction for designating the user device 2 and the connection change destination base station 3 notified from the terminal extraction unit 50 to the base station 3 to which the user device 2 is connected. To do. In the example illustrated in FIGS. 9 and 10, the user apparatus ue1 that changes the connection destination base station and the connection change instruction that specifies the connection change destination base station eNB2 are transmitted to the base station eNB4.

Next, the overall operation procedure of the communication system 1 will be described. FIG. 13 is an explanatory diagram of the HO operation. Now, as indicated by

arrows

60 and 61, it is assumed that the user apparatus ue1 is connected to the base station eNB4 and the user apparatus ue2 is connected to the base station eNB2.

In operations CA and CB, the base stations eNB2 and eNB4 respectively measure average throughput Tave, effective throughput Teff, and overall throughput Tall. The operations CA and CB correspond to the operation of the throughput measuring unit 25 shown in FIG.

In operation CC and CD, the user apparatuses ue2 and ue1 measure the surrounding radio environment and transmit measurement reports to the base stations eNB2 and eNB4. The operations CC and CD correspond to the operations of the wireless measurement unit 13 and the measurement report transmission unit 15 in FIG.

In operations CE and CF, the base stations eNB2 and eNB4 respectively generate load state information and transmit it to the load state analyzer 7. The operations CE and CF correspond to the operation of the load state information transmission unit 28 in FIG.

In operation CG, the load state analysis device 7 generates a load state list 47. In operation CH, the load state analysis device 7 generates a terminal state list 48. The operations CG and CH correspond to the operation of the state list generation unit 45 in FIG.

In operation CI, the load state analysis device 7 extracts the user device ue1 for changing the connection destination base station 3. In addition, the load state analysis device 7 selects the base station eNB2 that is the connection change destination of the extracted user device ue1. The operation CI is equivalent to the operation of the analysis unit 41 in FIG.

In operation CJ, the load state analysis device 7 transmits a connection change instruction to the base station eNB4. The operation CI corresponds to the operation of the connection change instruction transmission unit 42 in FIG.

In operation CK, the base station eNB4 determines a handover for changing the connection destination of the user apparatus ue1 to the base station eNB2 in accordance with the connection change instruction. In operation CL, the base station eNB4 transmits to the base station eNB2 a HO request for changing the connection destination of the user apparatus ue1 to the base station eNB2. The operations CK and CL correspond to the operation of the HO processing unit 30 in FIG.

In the operation CM, the base station eNB2 allocates hardware resources and radio resources of the base station eNB2 for connecting to the user apparatus ue1. In operation CN, the base station eNB2 transmits a HO response to the base station eNB4. The operations CM and CN correspond to the operation of the HO processing unit 30 in FIG.

In operation CO, the base station eNB4 transmits to the user apparatus ue1 a bearer reconfiguration request for executing a radio bearer reconfiguration procedure with the base station eNB2. The operation of the operation CO corresponds to the operation of the HO processing unit 30 in FIG. In response to the bearer reconstruction request, the HO processing unit 16 of the user apparatus ue1 starts a bearer construction procedure.

Thereafter, when synchronization between the user apparatus ue1 and the base station eNB2 is established as indicated by an arrow 62, the user apparatus ue1 transmits a connection completion report to the base station eNB2 in operation CP. The operation of the operation CP corresponds to the operation of the HO processing unit 16 in FIG.

In operation CQ, the base station eNB2 transmits to the base station eNB4 a path release request for requesting release of the communication path for the user apparatus ue1. The base station eNB4 releases the communication path for the user apparatus ue1. The operation CQ corresponds to the operation of the HO processing unit 30 in FIG. Thereafter, as indicated by an arrow 62, the user apparatus ue1 and the base station eNB2 start communication.

In the above description, the functional configuration diagrams of FIGS. 3, 5, and 8 mainly illustrate configurations related to the functions described in this specification. The user apparatus 2, the base station 3, and the load state analysis apparatus 7 may include other components other than the illustrated components. A series of operations described with reference to FIGS. 11 to 13 may be interpreted as a method including a plurality of procedures. In this case, “operation” may be read as “step”.

<6. Effect of Example>

According to the present embodiment, based on the actual measurement result of the load of the base station 3, the connection destination of the user apparatus 2 connected to the ground station 3 having a relatively high load is changed to the base station 3 having a relatively low load. Can be changed to As a result, the user apparatus 2 can communicate via the base station 3 having a relatively low load, and the throughput of the user apparatus 2 is improved. Moreover, the load imbalance between the base stations 3 is improved.

According to this embodiment, since the load on the base station 3 is determined based on the throughput, unlike a method for determining the load on the base station 3 based on the number of connected users, a small number of terminals are performing a large amount of data communication. However, the high load state of the base station 3 can be detected.

According to the present embodiment, the throughput measured by the base station 3 is collected by the load state analyzer 7, and the load state analyzer 7 determines whether the connection can be changed, the connection destination change target user device 2, the connection change destination The base station 3 is determined. For this reason, the load state analysis device 7 can change the connection destination of the user device 2 regardless of whether or not the user device 2 can perform a soft handover.

Therefore, even in a communication system in which the soft handover of the user apparatus 2 is not used, the load state analysis apparatus 7 can change the connection destination of the user apparatus 2. Also, in a communication system using soft handover, signaling can be reduced on a radio line for determining whether or not connection can be changed and the base station 3 that is the connection change destination.

<7. Modification>
In the above embodiment, the load state analysis device 7 is connected to the base station to which the user device 2 can connect based on whether or not the measurement report includes the wireless quality measurement result with a base station other than the connected base station 3. The presence or absence of a candidate for station 3 was determined. As a modification of the load state analysis device 7, the presence or absence of a candidate for the connectable base station 3 may be determined based on other information of the user device 2. For example, the load state analysis device 7 may determine whether there is a candidate for the connectable base station 3 based on the location information of the user device 2 and the location information of the base station 3.

Further, in the above embodiment, the load state analysis device 7 determines the load state of the base station 3 based on the throughput of the base station 3. The modification example of the load state analysis device 7 may determine the load state of the base station 3 based on another index indicating the load state of the base station 3. For example, the load state analysis device 7 may determine the load state of the base station 3 based on the hardware resources and radio resource occupancy of the base station 3 occupied by the processing for the user device 2.

<8. Hardware configuration>
Hereinafter, a hardware configuration example of each component of the communication system 1 will be described. FIG. 14 is a hardware configuration diagram of an example of the user device 2. The user device 2 includes a processor 100, a storage device 101, an LSI (Large Scale Integration) 102, and a wireless processing circuit 103.

The storage device 101 may include a non-volatile memory, a read-only memory (ROM: “Read Only Memory”), a random access memory (RAM: “Random Access Memory”), a flash memory, and the like for storing computer programs and data. . The processor 100 controls the operation of the user device 2 in accordance with a computer program stored in the storage device 101.

The LSI 102 performs baseband signal processing related to signal encoding and modulation, demodulation and decoding, communication protocol processing, and scheduling in accordance with a mobile communication wireless access scheme of a wireless channel between the user apparatus 2 and the base station 3. The LSI 102 may include FPGA (Field-Programming Gate Array), ASIC (Application Specific Integrated Circuit), DSP (Digital Signal Processing), and the like.

The wireless processing circuit 103 may include a digital / analog conversion circuit, an analog / digital conversion circuit, a frequency conversion circuit, an amplification circuit, a filter circuit, and the like.

The above operation of the control unit 10 shown in FIG. The operation of the wireless communication unit 11 may be executed by the wireless processing circuit 103. The above operation of the signal processing unit 12 may be executed by the LSI 102.

FIG. 15 is a hardware configuration diagram of an example of the base station 3. A processor 110, a storage device 111, an LSI 112, a wireless processing circuit 113, and a network interface circuit 114 are provided. In the following description and accompanying drawings, the network interface may be referred to as “NIF”.

The storage device 111 may include a nonvolatile memory, a read-only memory, a random access memory, a flash memory, a hard disk drive device, and the like for storing computer programs and data. The processor 110 controls the operation of the base station 3 according to the computer program stored in the storage device 111.

The LSI 112 executes signal processing in accordance with a mobile communication wireless access method of a wireless line between the base station 3 and the user device 2. Signal processing includes coding and modulation, and demodulation and decoding, communication protocol processing, and baseband signal processing for scheduling. The LSI 112 may include an FPGA, an ASIC, a DSP, and the like.

The wireless processing circuit 113 may include a digital / analog conversion circuit, an analog / digital conversion circuit, a frequency conversion circuit, an amplification circuit, a filter circuit, and the like. The NIF circuit 114 includes an electronic circuit that performs physical layer and data link layer processing for communication via a fixed communication line.

The above operation of the control unit 20 shown in FIG. The operation of the wireless communication unit 21 may be executed by the wireless processing circuit 113. The operation of the signal processing unit 22 may be executed by the LSI 112. The operation of the IF unit 23 may be executed by the NIF circuit 114.

FIG. 16 is a hardware configuration diagram of an example of the load state analysis device 7. The load state analysis device 7 includes a processor 120, a storage device 121, and an NIF circuit 122.

The storage device 121 may include a nonvolatile memory, a read-only memory, a random access memory, a flash memory, a hard disk drive device, and the like for storing computer programs and data. The processor 120 controls the operation of the load state analysis device 7 in accordance with a computer program stored in the storage device 121.

The NIF circuit 122 includes an electronic circuit that performs physical layer and data link layer processing for communication via a fixed communication line.

The above-described operations of the state information acquisition unit 40, the analysis unit 41, and the connection change instruction transmission unit 42 illustrated in FIG. The operation of the IF unit 43 may be executed by the NIF circuit 122.

Note that the hardware configurations shown in FIGS. 14 to 16 are merely examples for explaining the embodiments. Any other hardware configuration may be adopted for the user apparatus 2, the base station 3, and the load state analysis apparatus 7 described in this specification as long as the above-described operation is performed.

All examples and conditional terms contained herein are intended for educational purposes only to assist the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology. And should not be construed as being limited to the examples and conditions set forth above, as well as the configuration of the examples herein with respect to showing the superiority and inferiority of the present invention. Is. While embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications can be made thereto without departing from the spirit and scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Communication system 2, ue1 to ue5 User apparatus 3, eNB1 to eNB4 Base station 7 Load state analysis device 25 Throughput measurement unit 26 Measurement report reception unit 28 Load state information transmission unit 29 Connection change instruction reception unit 30 HO processing unit 42 Connection change Instruction transmitting unit 44 Load state information receiving unit 45 State list generating unit 49 Load monitoring unit 50 Terminal extracting unit

Claims

For each of a plurality of base station devices, a load state information receiving unit that receives load state information indicating a load state of the base station device measured by the base station device;
A first base station selection unit that selects the base station device in a load state that does not satisfy the allowable condition as a first base station device;
A mobile station selection unit that selects any of the mobile station devices connected to the first base station device;
A second base station selection unit that selects a second base station device other than the first base station device according to a load state of the second base station device;
An instruction to transmit to the first base station apparatus an instruction signal for changing the connection destination of any one of the mobile station apparatuses selected by the mobile station selection unit from the first base station apparatus to the second base station apparatus A signal transmitter;
A connection control device comprising:
The load state information includes information indicating communication throughput between the base station device and the mobile station device as the load state,
The first base station selection unit selects, as the first base station device, the base station device whose communication throughput exceeds a threshold value.
The connection control device according to claim 1.
The load state information includes a first communication throughput between the base station device and the mobile station device measured for each base station device, and between the base station device and the mobile station device measured for each mobile station device. Including information indicating the second communication throughput as the load state,
In the mobile station selection unit, a sum of the first communication throughput of a base station apparatus other than the first base station apparatus and the second communication throughput of a mobile station apparatus connected to the first base station apparatus exceeds a threshold value. 3. The connection control apparatus according to claim 1, wherein a mobile station apparatus whose sum is equal to or less than a threshold is selected as one of the mobile station apparatuses.
The load state information includes information indicating communication throughput between the base station device and the mobile station device measured for each mobile station device as the load state,
The mobile station selection unit selects, as one of the mobile station devices, a mobile station device whose communication throughput between the base station device and the mobile station device measured for each mobile station device is a threshold value or less. The connection control device according to claim 1, wherein:
The load state information includes an average throughput between the base station apparatus and the mobile station apparatus measured for each mobile station apparatus, and between the base station apparatus and the mobile station apparatus measured for each mobile station apparatus. Including effective throughput and information indicating the load state,
3. The mobile station apparatus according to claim 1, wherein the mobile station selection unit selects a mobile station apparatus whose ratio obtained by dividing the effective throughput by the average throughput is equal to or less than a threshold as the mobile station apparatus. Connection control device.
The mobile station selection unit selects any one of the mobile station devices depending on whether or not a base station device to which the mobile station device can be connected exists other than the first base station device. The connection control device according to any one of claims 1 to 5.
The mobile station selection unit is configured to connect the mobile station device according to radio quality received by the mobile station device from a base station device other than the first base station device or position information of the mobile station device. The connection control apparatus according to claim 6, wherein it is determined whether or not a base station apparatus other than one base station apparatus exists.
A base station device,
A load state measurement unit for measuring a load state of the base station device;
A radio quality information receiving unit that receives radio quality information from the mobile station device, measured with a mobile station device connected to the base station device, between the base station device other than the base station device;
A load state information transmitting unit for transmitting the wireless quality information to a predetermined information processing apparatus together with load information indicating the load state;
A designation signal for designating one of the mobile station apparatuses connected to the base station apparatus and one of the other base station apparatuses, which is transmitted by the predetermined information processing apparatus in response to the load information and the radio quality information. A designated signal receiver to receive;
A connection destination changing unit that changes a connection destination of the mobile station device specified by the specification signal from the base station device to a base station device specified by the specification signal;
A base station apparatus comprising:
A communication system comprising a plurality of base station devices and a connection control device,
The base station device
A load state measuring unit for measuring a load state indicating a load state of the base station device;
A load state information transmission unit for transmitting load state information indicating the load state to the connection control device;
An instruction signal for changing a connection destination of a mobile station device connected to the base station device from the base station device to another base station device other than the base station device among the plurality of base station devices, An instruction signal receiving unit that receives from the control device;
A connection destination changing unit that changes a connection destination of a mobile station device connected to the base station device according to the instruction signal;
With
The connection control device includes:
For each of the plurality of base station devices, a load state information receiving unit that receives the load state information;
A first base station selection unit that selects the base station device in a load state that does not satisfy the allowable condition as a first base station device;
A mobile station selection unit that selects any of the mobile station devices connected to the first base station device;
A second base station selection unit that selects a second base station device other than the first base station device according to a load state of the second base station device;
An instruction to transmit to the first base station apparatus an instruction signal for changing the connection destination of any one of the mobile station apparatuses selected by the mobile station selection unit from the first base station apparatus to the second base station apparatus A signal transmitter;
A communication system comprising:
For each of a plurality of base station devices, measure the load state of the base station device,
Selecting the base station device in a load state that does not satisfy the allowable condition as a first base station device;
Select one of the mobile station devices connected to the first base station device,
A second base station device other than the first base station device is selected according to the load state of the second base station device,
Changing the connection destination of any one of the selected mobile station devices from the first base station device to the second base station device;
A communication method characterized by the above.