JP2015073298A - Radio base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio base station capable of appropriate handover in consideration of the throughput of a radio terminal.SOLUTION: A handover request message S107 for causing a radio base station eNB 10-1 to perform handover to a radio base station eNB 10-2 includes information S103-1 indicative of the degree of satisfaction of a throughput when a radio terminal UE 30-1 executes an application relative to a throughput required for the radio terminal UE 30-1 to execute the application. The radio base station eNB 10-2 controls a response to the handover request message according to the information indicative of the degree of satisfaction included in the handover request message (S108-110).

Description

  The present invention relates to a radio communication technique, and more particularly to a radio base station that controls handover of a radio terminal.

  In LTE (Long Term Evolution) standardized by 3GPP (3rd Generation Partnership Project), which is a standardization organization for wireless communication systems, a technology called SON (Self Organizing Network) is employed. According to SON, when installing and maintaining a wireless base station, it is expected to be automated without requiring manual measurement and setting in the field (for example, see Non-Patent Document 1).

  In SON, in order to level the load between radio base stations (called “eNB” in 3GPP), a method of adjusting coverage based on load information transmitted and received between radio base stations has been proposed. ing. In this coverage adjustment method, when there is a radio base station with a high load and a radio base station with a low load at the time of a handover, a radio terminal connected to the radio base station with a high load is transferred to the radio base station with a low load. Hand over.

3GPP TR 36.902 V9.1.0 April, 2010.

  However, the method in which handover is performed based on load information has the following problems. Specifically, even if the load of the first radio base station and the load between the second radio base stations are leveled, the throughput of the radio terminal connected to the first radio base station and the second radio There is a problem that the throughput of the wireless terminal connected to the base station is not considered.

  Accordingly, an object of the present invention is to provide a radio base station and a handover control method that enable an appropriate handover in consideration of the throughput of the radio terminal.

  In order to solve the above-described problems, the present invention has the following features.

  A feature of the radio base station according to the present invention is a radio base station (radio base station eNB10-2) to which a radio terminal (radio terminal UE30-2) is connected, and other radio base stations (radio base station eNB-1). ) And receives a handover request (Handover Request message) for a wireless terminal (wireless terminal UE30-1) connected to the other wireless base station to perform a handover to the own station (wireless base station eNB10-2). Receiving unit (network communication unit 140-2) and a transmission unit (network communication unit 140-2) that transmits a response to the handover request (Handover Request Ack message or Handover Request Nack message) to the other radio base station. ) And a control unit (control unit 120-2) that controls a response to the handover request. Including a first information indicating a sufficiency of throughput when the wireless terminal executes the application with respect to a throughput required for the wireless terminal connected to the wireless base station to execute the application, The gist is to control a response to the handover request in accordance with the first information included in the handover request.

  Another feature of the radio base station according to the present invention is that, in the above-described feature, the control unit performs the handover according to a comparison result between the first information and the second information included in the handover request. The response to the request is controlled, and the second information is related to the throughput required for the radio terminal (radio terminal UE30-2) connected to the local station (radio base station eNB10-2) to execute the application. The gist is to indicate the sufficiency of throughput when the wireless terminal executes the application.

  Another feature of the radio base station according to the present invention is that, in the above-described feature, the control unit satisfies the sufficiency indicated by the first information, which is indicated by the first information included in the handover request. The gist is to perform control so as to transmit an acknowledgment (Handover Request Ack message) to the handover request when it is lower than the degree.

  Another feature of the radio base station according to the present invention is that, in the above-described feature, the control unit satisfies the sufficiency indicated by the first information, which is indicated by the first information included in the handover request. The gist is to perform control so as to transmit a negative response (Handover Request Nack message) to the handover request when it is higher than the threshold.

  A feature of the radio base station according to the present invention is a radio base station (radio base station eNB10-1) to which the radio terminal (radio terminal UE30-1) is connected, and is connected to the own station (radio base station eNB10-1). A wireless terminal (wireless terminal UE30-1) to transmit a handover request (Handover Request message) for performing a handover to another wireless base station (wireless base station eNB10-2) to the other wireless base station A transmission unit (network communication unit 140-1), which is required for the wireless terminal (wireless terminal UE30-1) connected to the own station (wireless base station eNB10-1) to execute an application; The first request indicating the degree of satisfaction of the throughput when the wireless terminal executes the application with respect to the throughput to be transmitted is included in the handover request. The gist is to do.

  Another feature of the radio base station according to the present invention is that, in the above-described feature, the transmitting unit transmits the handover request when a sufficiency level indicated by the first information is less than a threshold value. And

  A feature of the handover control method according to the present invention is a handover control method in a radio base station to which a radio terminal is connected. The radio terminal transmitted by another radio base station and connected to the other radio base station is Receiving a handover request for performing a handover to, and transmitting a response to the handover request to the other radio base station, wherein the handover request is transmitted to the other radio base station. Including the first information indicating the sufficiency of the throughput when the wireless terminal executes the application with respect to the throughput required for the wireless terminal connected to the mobile station to execute the application, and the transmitting step includes the handover A response to the handover request according to the first information included in the request To increase the transmission.

  A feature of the handover control method according to the present invention is a handover control method in a radio base station to which a radio terminal is connected, in which a radio terminal connected to its own station issues a handover request for performing a handover to another radio base station. A step of transmitting to the other radio base station, wherein the step of transmitting the wireless terminal executes the application for a throughput required for the wireless terminal connected to the local station to execute the application. The gist is to transmit the first information indicating the degree of satisfaction of the throughput when the handover request is included in the handover request.

  According to the present invention, it is possible to provide a radio base station and a handover control method that enable an appropriate handover in consideration of the throughput of the radio terminal.

It is a figure for demonstrating the outline | summary of the LTE system which concerns on embodiment of this invention. 1 is a schematic configuration diagram of a radio communication system according to an embodiment of the present invention. It is a block diagram which shows the structure of the wireless base station (eNB10-1) which concerns on embodiment of this invention. It is a block diagram which shows the structure of the wireless base station (eNB10-2) which concerns on embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless terminal which concerns on embodiment of this invention. It is an operation | movement sequence diagram which shows operation | movement of the radio | wireless communications system concerning embodiment of this invention.

  Next, an embodiment of the present invention will be described with reference to the drawings. Specifically, (1) Overview of LTE system, (2) Configuration of radio communication system, (3) Configuration of radio base station, (4) Configuration of radio terminal, (5) Operation of radio communication system, (6 ) Actions and effects, (7) Other embodiments will be described. In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

(1) Overview of LTE System FIG. 1 is a diagram for describing an overview of an LTE system. As shown in FIG. 1, a plurality of radio base stations eNB constitutes an E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network). Each of the plurality of radio base stations eNB forms one or a plurality of cells that are the minimum unit of the communication area that should provide a service to the radio terminal UE.

  The radio terminal UE is a radio communication device possessed by a user and is also referred to as a user device. The radio terminal UE measures the quality (that is, radio quality) of the radio signal received from the radio base station eNB, and transmits a report of the radio quality measurement result (hereinafter, measurement result report) to the connection-destination radio base station eNB. To do.

  Such radio quality includes reference signal received power (RSRP), signal-to-interference noise ratio (SINR), and the like. A measurement result report related to RSRP is called a measurement report, and a measurement result report related to an SINR index for each specific frequency band is called a CQI (Channel Quality Indicator).

  The radio base station eNB to which the radio terminal UE is connected performs a handover procedure for switching the connection destination of the radio terminal UE based on the measurement report received from the radio terminal UE. When the radio terminal UE receives reference signals from a plurality of radio base stations eNB, the measurement report includes a plurality of RSRPs corresponding to the plurality of radio base stations eNB (plural cells). The radio base station eNB to which the radio terminal UE is connected usually selects a radio base station eNB (a plurality of cells) having the highest RSRP as the connection destination of the radio terminal UE.

  Also, the radio base station eNB to which the radio terminal UE is connected allocates resource blocks, which are radio resource allocation units, to the radio terminal UE based on the CQI received from the radio terminal UE. Furthermore, the radio base station eNB to which the radio terminal UE is connected determines a modulation class to be used for radio communication with the radio terminal UE based on the CQI received from the radio terminal UE. The modulation class is a combination of the modulation multi-level number and the coding rate.

  Each radio base station eNB can communicate with each other via an X2 interface which is a logical communication path that provides communication between base stations. Each of the plurality of radio base stations eNB can communicate with EPC (Evolved Packet Core), specifically, MME (Mobility Management Entity) / S-GW (Serving Gateway) via the S1 interface.

(2) Configuration of Radio Communication System FIG. 2 is a schematic configuration diagram of the radio communication system 1 according to the present embodiment.

  As illustrated in FIG. 2, the radio communication system 1 includes a radio base station eNB10-1 and a radio terminal UE30- connected to the radio base station eNB10-1 in a cell C20-1 formed by the radio base station eNB10-1. 1 and a radio terminal UE30-2 connected to the radio base station eNB10-2 in a cell C20-2 formed by the radio base station eNB10-2. The radio base station eNB10-1 and the radio base station eNB10-2 can perform inter-base station communication using the X2 interface described above. In FIG. 2, only one of each of the radio terminal UE30-1 and the radio terminal UE30-2 is illustrated, but actually, there are a plurality of radio terminals UE30-1 and radio terminals UE30-2. Shall.

  In the present embodiment, together with the adjustment of the handover parameter based on the load information described above, each radio base station eNB determines whether the radio terminal UE has a throughput (hereinafter, requested throughput) required for the radio terminal UE to execute an application. The handover procedure of the radio terminal UE is controlled based on the degree of throughput (hereinafter referred to as actual throughput) measured when the application is executed (hereinafter referred to as throughput satisfaction).

(3) Configuration of Radio Base Station (3.1) Configuration of Radio Base Station eNB10-1 Next, the configuration of the radio base station eNB10-1 will be described. FIG. 3 is a block diagram illustrating a configuration of the radio base station eNB10-1 according to the present embodiment.

  As illustrated in FIG. 3, the radio base station eNB10-1 includes an antenna unit 101-1, a radio communication unit 110-1, a control unit 120-1, a storage unit 130-1, and a network communication unit 140-1.

  The antenna unit 101-1 is used for transmission / reception of radio signals. The radio communication unit 110-1 is configured using, for example, a radio frequency (RF) circuit, a baseband (BB) circuit, or the like, and transmits and receives radio signals to and from the radio terminal UE30-1 via the antenna unit 101-1. Further, the wireless communication unit 110-1 performs modulation of the transmission signal and demodulation of the reception signal.

  The control unit 120-1 is configured using, for example, a CPU, and controls various functions provided in the radio base station eNB10-1. The storage unit 130-1 is configured using, for example, a memory, and stores various types of information used for controlling the radio base station eNB10-1. The network communication unit 140-1 performs inter-base station communication with another adjacent radio base station eNB10-2 using the X2 interface. The network communication unit 140-1 communicates with the EPC using the S1 interface.

  The control unit 120-1 includes a handover control unit 121-1, and a transmission control unit 122-1.

  The radio communication unit 110-1 receives the throughput satisfaction degree information message transmitted from each of the radio terminals UE30-1 connected to the radio base station eNB10-1 via the antenna unit 101-1. The throughput sufficiency level information includes a throughput (actual measurement throughput) measured when the radio terminal UE30-1 executes an application with respect to a throughput (requested throughput) required for the radio terminal UE30-1 as a transmission source to execute the application. ) Degree (throughput satisfaction degree). Here, the throughput generally means the amount of communication data per unit time, and in this embodiment, is the throughput between the radio base station eNB and the radio terminal UE. The radio communication unit 110-1 outputs the received throughput satisfaction degree information to the handover control unit 121-1.

  The handover control unit 121-1 recognizes the throughput satisfaction degree in the wireless terminal UE 30-1 for each wireless terminal UE 30-1 based on the input throughput satisfaction degree information message for each wireless terminal UE 30-1. Next, the handover controller 121-1 calculates the average value of the recognized throughput satisfaction levels. The average value (hereinafter, “first overall throughput satisfaction degree”) indicates the degree of actually measured throughput with respect to the overall required throughput of the plurality of radio terminals UE30-1 connected to the radio base station eNB10-1.

  The handover controller 121-1 determines whether or not the first overall throughput satisfaction is less than the first threshold. Here, the first threshold value is a minimum value of the first overall throughput satisfaction when the radio terminal UE30-1 connected to the radio base station eNB10-1 is not handed over to another radio base station eNB10-2. The first threshold value is stored in advance in the storage unit 130-1.

  When the first overall throughput satisfaction degree is less than the first threshold, the handover control unit 121-1 needs to hand over the radio terminal UE30-1 connected to the radio base station eNB10-1 to the radio base station eNB10-2. Recognize that there is. Furthermore, the handover control unit 121-1 selects any one of the radio terminals UE30-1 connected to the radio base station eNB10-1 as a handover target. For example, the handover control unit 121-1 has the lowest corresponding throughput satisfaction degree among the radio terminals UE 30-1 connected to the radio base station eNB 10-1, or the corresponding throughput is low. A predetermined number of radio terminals UE30-1 are selected as handover targets.

  The transmission control unit 122-1 includes information on the first overall throughput satisfaction level, and outputs a Handover Request message for requesting to become a handover destination of the handover target radio terminal UE30-1 to the network communication unit 140-1. To do. Furthermore, the transmission control unit 122-1 controls the network communication unit 140-1 to transmit a Handover Request message to the radio base station eNB 10-2.

  The network communication unit 140-1 transmits a Handover Request message including the first overall throughput satisfaction degree information to the radio base station eNB10-2 via the X2 interface according to the control of the transmission control unit 122-1. To do.

  Then, the network communication unit 140-1 receives a Handover Request Ack message (acknowledgment) or a Handover Request Nack message (acknowledgment) via the X2 interface as a response from the radio base station eNB10-2 to the Handover Request message. To do.

  When the network communication unit 140-1 receives the Handover Request Ack message, the handover control unit 121-1 generates a Handover command message for instructing handover to the handover target radio terminal UE30-1. Furthermore, the handover control unit 121 outputs a Handover command message to the wireless communication unit 110. The radio communication unit 110 transmits a Handover command message to the radio terminal UE30-1 that is a handover target via the antenna unit 101. On the other hand, when the network communication unit 140-1 receives the Handover Request Nack message, the handover control unit 121-1 does not generate a Handover command message.

(3.2) Configuration of Radio Base Station eNB10-2 Next, the configuration of the radio base station eNB10-2 will be described. FIG. 4 is a block diagram showing a configuration of the radio base station eNB10-2 according to the present embodiment.

  As illustrated in FIG. 4, the radio base station eNB10-2 includes an antenna unit 101-2, a radio communication unit 110-2, a control unit 120-2, a storage unit 130-2, and a network communication unit 140-2.

  The antenna unit 101-2 is used for transmission / reception of a radio signal. The radio communication unit 110-2 is configured using, for example, a radio frequency (RF) circuit, a baseband (BB) circuit, and the like, and transmits and receives radio signals to and from the radio terminal UE30-2 via the antenna unit 101-2. In addition, the wireless communication unit 110-2 performs modulation of the transmission signal and demodulation of the reception signal.

  The control unit 120-2 is configured using, for example, a CPU, and controls various functions provided in the radio base station eNB10-2. The control unit 120-2 includes a handover control unit 121-2 and a transmission control unit 122-2.

  Storage part 130-2 is constituted using memory, for example, and memorizes various information used for control etc. of base transceiver station eNB10-2.

  The network communication unit 140-2 performs inter-base station communication with another adjacent radio base station eNB10-1 using the X2 interface. The network communication unit 140-2 communicates with the EPC using the S1 interface. The network communication unit 140-2 receives the Handover Request message including the first overall throughput satisfaction degree information. The handover control unit 121-2 is similar to the above-described handover control unit 121-1 of the radio base station eNB10-1, and the throughput satisfaction degree information for each radio terminal UE30-2 connected to the radio base station eNB10-2. Based on the message, the wireless terminal UE30-2 recognizes the throughput sufficiency in the radio terminal UE30-2. The handover control unit 121-2 calculates an average value of the recognized throughput satisfaction levels. The average value (hereinafter, “second overall throughput satisfaction degree”) indicates the degree of actually measured throughput with respect to the overall required throughput of the plurality of radio terminals UE30-2 connected to the radio base station eNB10-2.

  The network communication unit 140-2 outputs the first overall throughput satisfaction degree information included in the Handover Request message to the handover control unit 122-2. Next, when the first overall throughput satisfaction degree information is input, the handover control unit 121-2 determines whether the first overall throughput satisfaction degree is smaller than the second overall throughput satisfaction degree.

  When the first overall throughput satisfaction degree is equal to or higher than the second overall throughput satisfaction degree, the connection destination of the radio terminal UE30-1 connected to the radio base station eNB10-1 is switched to the radio base station eNB10-2 by handover. And the improvement of the throughput of the remaining radio terminals UE30-1 connected to the radio base station eNB10-1 can be expected. However, although the throughput of the radio terminal UE30-2 connected to the radio base station eNB10-2 is low before the handover, the radio terminal UE30-1 is newly connected to the radio base station eNB10-2 As a result, the throughput may further decrease, and the throughput between the radio base station eNB10-1 and the radio base station eNB10-2 cannot be leveled.

  For this reason, when the first overall throughput satisfaction degree is equal to or higher than the second overall throughput satisfaction degree, the handover control unit 122-2 determines to reject the Handover Request message from the radio base station eNB10-1. In this case, the transmission control unit 122-2 outputs a Handover Request Nack message that is a negative response to the network communication unit 140 as a response to the Handover Request message. Furthermore, the transmission control unit 122-2 controls the network communication unit 140-2 so as to transmit the Handover RequestNack message to the radio base station eNB10-1. The network communication unit 140-2 transmits a Handover Request Nack message to the radio base station eNB10-1 via the X2 interface according to the control of the transmission control unit 122-2.

  On the other hand, when the first overall throughput satisfaction is less than the second overall throughput satisfaction, the connection destination of the radio terminal UE30-1 connected to the radio base station eNB10-1 is changed to the radio base station eNB10-2 by handover. When switching to, it is possible to improve the throughput of the remaining radio terminal UE30-1 connected to the radio base station eNB10-1. Moreover, although the throughput of the radio terminal UE30-2 connected to the radio base station eNB10-2 decreases when the radio terminal UE30-1 is newly connected to the radio base station eNB10-2, the radio base station eNB10 -1 and the radio base station eNB10-2 can be leveled.

  For this reason, when the first overall throughput satisfaction is less than the second overall throughput satisfaction, the handover control unit 122-2 determines to allow the Handover Request message from the radio base station eNB10-1. In this case, the transmission control unit 122-2 outputs a Handover Request Ack message that is an affirmative response to the network communication unit 140-2 as a response to the Handover Request message. Furthermore, the transmission control unit 122-2 controls the network communication unit 140-2 so as to transmit the Handover Request Ack message to the radio base station eNB10-1. The network communication unit 140-2 transmits a Handover Request Ack message to the radio base station eNB10-1 via the X2 interface according to the control of the transmission control unit 122-2.

(4) Configuration of Radio Terminal Next, the configuration of the radio terminal UE30-1 will be described. FIG. 5 is a block diagram showing a configuration of the radio terminal UE30-1 according to the present embodiment. The radio terminal UE30-2 has the same configuration as the radio terminal UE30-1.

  As illustrated in FIG. 5, the radio terminal UE30-1 includes an antenna unit 201, a radio communication unit 210, a control unit 220, a storage unit 230, and an operation unit 240.

  The antenna unit 201 is used for transmitting and receiving radio signals. The radio communication unit 210 is configured using, for example, a radio frequency (RF) circuit, a baseband (BB) circuit, or the like, and transmits and receives radio signals to and from the radio base station eNB via the antenna unit 201. The wireless communication unit 210 also modulates the transmission signal and demodulates the reception signal.

  The control unit 220 is configured using, for example, a CPU, and controls various functions included in the radio terminal UE30-1. The storage unit 230 is configured using, for example, a memory, and stores various types of information used for controlling the radio terminal UE30-1. The operation unit 240 is composed of a numeric keypad, function keys, and the like, and is an interface used for inputting user operation details.

  The control unit 220 includes an application execution unit 221, a throughput sufficiency information generation unit 222, and a transmission control unit 223.

  When an operation signal corresponding to an operation of executing the application of the operation unit 240 by the user is input from the operation unit 240, the application execution unit 221 reads an application program from the storage unit 130 according to the operation signal. ,Run. Here, the application to be executed is an application that requires wireless communication with the wireless base station eNB10-1, such as a web browser, streaming reproduction of video and audio, and voice communication using VoIP.

  The throughput sufficiency level information generation unit 222 acquires information on throughput (requested throughput) required for the application execution unit 221 to execute an application.

  Specifically, the storage unit 230 stores, for each application that can be executed in the radio terminal UE30-1, information on the requested throughput in the execution of the application. The throughput sufficiency level information generation unit 222 recognizes the application being executed by the application execution unit 221 and reads out the requested throughput information corresponding to the application from the storage unit 230.

  Alternatively, the user operates the operation unit 240 to perform an operation for setting the requested throughput of the application executed by the application execution unit 221. In this case, the throughput sufficiency level information generation unit 222 recognizes the application being executed by the application execution unit 221 and recognizes the requested throughput corresponding to the application based on the operation signal from the operation unit 240.

  Next, the throughput sufficiency degree information generation unit 222 measures the throughput between the radio base station eNB10-1 and the radio terminal UE30-1 while the application is being executed by the application execution unit 221. In the present embodiment, the measured throughput is both or one of the uplink direction and the downlink direction.

  The throughput sufficiency level information generation unit 222 calculates the throughput sufficiency level by dividing the measured throughput (actually measured throughput) by the requested throughput. When the throughput is measured in both the uplink and downlink directions, the throughput sufficiency information generation unit 222 divides the actually measured throughput in the uplink direction by the requested throughput in the uplink direction to satisfy the throughput in the uplink direction. And calculating the degree of satisfaction of the downlink throughput by dividing the actually measured throughput of the downlink by the requested throughput of the downlink, and calculating the degree of satisfaction of the uplink throughput and the degree of satisfaction of the downlink throughput. The average value may be calculated as the sufficiency of throughput. The throughput sufficiency information generation unit 222 may convert the value obtained by dividing the actually measured throughput by the required throughput into a discrete value such as 1 to 10 to obtain the throughput sufficiency.

  The throughput sufficiency level information generation unit 222 weights the calculated throughput sufficiency level according to the codec rate of data transmitted in the execution of the application. Specifically, the throughput sufficiency information generation unit 222 weights the throughput sufficiency so that the sufficiency becomes higher as the codec rate becomes higher, and the throughput sufficiency information indicating the weighted sufficiency sufficiency is obtained. Generate.

  The transmission control unit 223 outputs the throughput sufficiency level information to the radio communication unit 210 and controls the radio communication unit 210 to transmit the throughput sufficiency level information to the radio base station eNB10-1. The radio communication unit 210 transmits throughput sufficiency information to the radio base station eNB10-1 via the antenna unit 101 under the control of the transmission control unit 223.

  Thereafter, when the radio base station eNB10-1 transmits a Handover command message to the radio terminal UE30-1, the radio communication unit 110 receives the Handover command message via the antenna unit 101. Further, the wireless communication unit 110 outputs a Handover command message to the control unit 220.

  When the Handover command message is input, the control unit 220 performs a handover procedure for switching the connection destination from the radio base station eNB10-1 to another radio base station eNB10-2 according to the Handover command message.

(5) Operation of Radio Communication System FIG. 6 is an operation sequence diagram showing the operation of the radio communication system 1 according to this embodiment.

  In step S101-1, the throughput sufficiency level information generation unit 222 of the radio terminal UE30-1 measures the throughput when the application is executed.

  In step S102-1, the throughput sufficiency information generation unit 222 of the radio terminal UE30-1 performs weighting on the throughput sufficiency according to the codec rate, and provides throughput sufficiency information indicating the weighted sufficiency sufficiency. Generate.

  In step S103-1, the radio communication unit 210 of the radio terminal UE30-1 transmits throughput sufficiency information to the radio base station eNB10-1 via the antenna unit 101. The radio communication unit 110-1 of the radio base station eNB10-1 receives the throughput satisfaction degree information from each radio terminal UE30-1 via the antenna unit 101-1.

  Similarly, in step S101-2, the throughput sufficiency level information generation unit 222 of the radio terminal UE30-2 measures the throughput when the application is executed.

  In step S102-2, the throughput sufficiency information generation unit 222 of the radio terminal UE30-2 weights the throughput sufficiency according to the codec rate, and provides throughput sufficiency information indicating the weighted sufficiency sufficiency. Generate.

  In step S103-2, the radio communication unit 210 of the radio terminal UE30-2 transmits the throughput sufficiency information to the radio base station eNB10-2 via the antenna unit 101. The radio communication unit 110-2 of the radio base station eNB10-2 receives the throughput sufficiency information from each radio terminal UE30-2 via the antenna unit 101-2.

  In addition, the procedure of step S101-S103 may be performed regularly and may be performed by the instruction | indication from the base station eNB.

  In step S104, the handover control unit 121-1 of the radio base station eNB10-1 calculates the first overall throughput satisfaction degree based on the throughput satisfaction degree information message for each radio terminal UE30-1.

  In step S105, the handover controller 121-1 of the radio base station eNB10-1 determines whether or not the first overall throughput satisfaction is less than the first threshold. When the first overall throughput satisfaction level is equal to or higher than the first threshold value, the series of operations ends.

  On the other hand, when the first overall throughput sufficiency is less than the first threshold, in step S106, the handover control unit 121-1 of the radio base station eNB10-1 determines that the radio terminal UE30 is connected to the radio base station eNB10-1. -1 to select a radio terminal UE30-1 to be handed over.

  In step S107, the network communication unit 140-1 of the radio base station eNB10-1 transmits a Handover Request message including information on the first overall throughput satisfaction degree under the control of the transmission control unit 122-1. The network communication unit 140-2 of the radio base station eNB10-2 receives the Handover Request message including the first overall throughput satisfaction degree information.

  In Step S108, the handover control unit 121-2 of the radio base station eNB10-2 generates (calculates) information on the second overall throughput satisfaction degree based on the throughput satisfaction degree information message for each wireless terminal UE30-2.

  In step S109, the handover control unit 121-2 of the radio base station eNB10-2 compares the first overall throughput satisfaction degree with the second overall throughput satisfaction degree, and the first overall throughput satisfaction degree is the second overall throughput satisfaction degree. It is determined whether it is smaller.

  If the first overall throughput satisfaction level is equal to or higher than the second overall throughput satisfaction level, in step S110, the network communication unit 140-2 wirelessly transmits via the X2 interface according to the control of the transmission control unit 122-2. A Handover Request Nack message is transmitted to the base station eNB10-1.

  On the other hand, if the first overall throughput satisfaction degree is less than the second overall throughput satisfaction degree, in step S110, the network communication unit 140-2 passes through the X2 interface according to the control of the transmission control unit 122-2. Then, a Handover Request Ack message is transmitted to the radio base station eNB10-1.

  The X2 interface communication unit 140-1 of the radio base station eNB10-1 receives the Handover Request Ack message or the Handover Request Nack message. In step S111, the handover controller 121-1 of the radio base station eNB10-1 determines whether a Handover Request Ack message or a Handover Request Nack message has been received from the radio base station eNB10-2. When a Handover Request Nack message is received from the radio base station eNB10-2, a series of operations ends.

  On the other hand, when the Handover Request Ack message is received from the radio base station eNB10-2, the radio communication unit 110 of the radio base station eNB10-1 is a target for handover via the antenna unit 101 in step S112. A Handover command message is transmitted to the radio terminal UE30-1. The radio communication unit 210 of the radio terminal UE30-1 that is a handover target receives the Handover command message. Thereafter, the radio terminal UE30-1 that is the target of the handover performs a handover procedure for switching the connection destination from the radio base station eNB10-1 to another radio base station eNB10-2.

(6) Operation / Effect As described above, according to the present embodiment, the radio base station eNB10-2 is transmitted by the radio base station eNB-1 and connected to the radio base station eNB-1. 1 receives a Handover Request message for performing a handover to the radio base station eNB10-2, and then transmits a response to the Handover Request message (Handover Request Ack message or Handover Request Nack message) to the radio base station eNB-1 To do. The Handover Request message indicates the degree of throughput satisfaction (first overall throughput satisfaction degree) when the radio terminal UE30-1 executes the application with respect to the throughput required for the radio terminal UE30-1 to execute the application. Contains information. The radio base station eNB10-2 controls a response to the Handover Request message according to the information indicating the sufficiency (first overall throughput sufficiency) included in the Handover Request message. Thereby, the radio base station eNB10-2 can determine whether to allow or reject the Handover Request message in consideration of the throughput of the radio terminal UE30-1 connected to the radio base station eNB10-1.

  In the present embodiment, the radio terminal UE30-1. Weighting is performed on the throughput satisfaction so that the higher the codec rate of the data transmitted in the execution of the application, the higher the satisfaction. When an application for playing back audio and video is executed in the radio terminal UE30-1, the higher the codec rate is, the better the quality of the audio and video, and thus the degree of user satisfaction is increased. By reflecting the satisfaction level of the user, which changes depending on the codec rate, in the throughput satisfaction level, the throughput satisfaction level can be made closer to the user's sense.

(7) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the embodiment described above, the radio terminal UE30-1 calculates the throughput satisfaction by dividing the actually measured throughput by the required throughput. However, the throughput sufficiency may be corrected as follows.

  That is, when data (processing target data) used in an application is transmitted from the radio base station eNB10-1 and input to the storage unit 230 of the radio terminal UE30-1, and then output, the throughput sufficiency information generation unit 222 calculates the difference between the input speed and the output speed of the processing target data in the storage unit 230. Furthermore, if the calculated difference is within a predetermined range, the throughput sufficiency information generation unit 222 is 1 even if the throughput sufficiency calculated by dividing the actually measured throughput by the requested throughput is less than 1. That is, a throughput sufficiency level indicating that the actually measured throughput satisfies the required throughput is set.

  In the above-described embodiment, the throughput sufficiency level information generation unit 222 performs weighting according to the codec rate to the value obtained by dividing the actually measured throughput by the requested throughput. However, the weighting may not be performed.

  In the above-described embodiment, the radio base station eNB10 calculates an overall throughput satisfaction degree that is the satisfaction degree of the entire throughput of each radio terminal UE30, and performs a handover procedure based on the overall throughput satisfaction degree. However, the radio base station eNB10 performs a handover procedure for the single radio terminal UE30 based on the throughput satisfaction degree information of the single radio terminal UE30 from the single radio terminal UE30. Also good.

  In LTE Advanced, it is planned to adopt a relay node that is a radio base station that configures the backhaul by radio, and an X2 interface is also planned to be adopted for the relay node. The second radio base station may be used.

  In the above-described embodiment, the case where the backhaul is the X2 interface has been described. However, the present invention can be similarly applied when the backhaul is the S1 interface or when the backhaul is the X2 interface and the S1 interface.

  Furthermore, although the LTE system has been described in the above-described embodiment, the present invention may be applied to other wireless communication systems such as a wireless communication system based on WiMAX (IEEE802.16).

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

  UE30 ... radio terminal, eNB10 ... radio base station, 1 ... radio communication system, 101 ... antenna unit, 110 ... radio communication unit, 120 ... control unit, 121 ... handover control unit, 122 ... transmission control unit, 130 ... storage unit, DESCRIPTION OF SYMBOLS 140 ... Network communication part 201 ... Antenna part 210 ... Wireless communication part 220 ... Control part 221 ... Application execution part 222 ... Throughput sufficiency information generation part 223 ... Transmission control part 230 ... Memory | storage part 240 ... Operation part

Claims (2)

A wireless base station to which a wireless terminal is connected,
A wireless terminal connected to the local station has a transmission unit for transmitting a handover request for performing handover to another wireless base station to the other wireless base station;
The transmitting unit is based on first information indicating a sufficiency of throughput when the wireless terminal executes the application with respect to a throughput required for the wireless terminal connected to the local station to execute the application. Send a handover request,
A wireless base station characterized by that. The transmitting unit transmits the handover request when a sufficiency level indicated by the first information is less than a threshold;
The radio base station according to claim 1.

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