JP2008205600A - Base station, wireless communication terminal and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication terminal capable of acquiring information about traffic conditions of QoS communication of peripheral base stations which can be handoff destination candidates from a base station. <P>SOLUTION: The wireless communication terminal 100 includes a peripheral base station information storage part 280a which holds information of handoff destination candidate base stations; an information acquisition part 250 which acquires information about the traffic conditions of QoS communication of the handoff destination candidate base stations, on the basis of notification information received from the base station being performing QoS communication; a handoff destination candidate determining part 250b which determines whether each of handoff destination candidate base stations should be included in handoff destination candidate base stations, on the basis of the acquired information about the traffic conditions of QoS communication and reception field intensities of the handoff destination candidate base stations; and a notification part 250d, which notifies the base station being performing QoS communication about handoff destination candidate base stations that are determined as being included in the handoff destination candidate base stations. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a base station capable of performing QoS communication, a wireless communication terminal capable of performing QoS communication, and a communication control method capable of performing QoS communication between the base station and the wireless communication terminal. It is about.

In a mobile communication system using a CDMA (Code Division Multiple Access) method, a plurality of methods are generally adopted and introduced as a method of data transmission including moving image data transmitted and received in an application such as an IP-TV phone. Has been.
For example, in CDMA2000, as a data transmission method, a communication method using circuit switching (CDMA2000 1x) and a packet switching method are used, and a data rate (transmission speed) of uplink: 153.6 kbps and downlink: about 2.4 Mbps. (CDMA2000 1x EV-DO Rev. 0) and the Rev. A communication method (CDMA2000 1x EV-DO Rev. A) is defined that further speeds up the communication method of 0 and realizes a data rate (transmission speed) of about 1.8 Mbps in the upstream direction and about 3.1 Mbps in the downstream direction. (For example, see Non-Patent Document 1 and Non-Patent Document 2).
In addition, CDMA2000 1x EV-DO Rev. Another feature of A is that a function for controlling QoS (Quality of Service) is added.

  For example, in a conventional mobile communication system including a large number of wireless communication terminals and a plurality of base stations (in the illustrated example, base station A and base station B) shown in FIG. When the radio communication terminal a in communication with the base station A using the radio wave strength of the base station B becomes stronger than the base station A when moving to the β point, In order to handoff to the base station B, a handoff request is sent to the base station A, and when a handoff response is received from the base station A that permits the base station A and the base station B as communication destinations, the handoff to the base station B is performed. Then, communication with the base station B using QoS is performed. In the example shown in FIG. 15, the number of wireless communication terminals (hereinafter referred to as the number of QoS using terminals) communicating with the base station A using QoS is three including the wireless communication terminal a. The number of terminals using B's QoS is seven.

"Cdma2000 High Rate Packet Data Air Interface 3GPP2 C.S0024 Version 4.0", 3GPP2, October 2002 (Section 8.5.6.1, Section 9.3.1.3.2.3.2) “Cdma2000 High Rate Packet Data Air Interface 3GPP2 C.S0024-A Version 2.0”, 3GPP2, July 2005 (Section 13.2.1.3.1.1, Section 13.3.1.3.1.1)

  In the conventional mobile communication system shown in FIG. 15, a wireless communication terminal (hereinafter also referred to as a terminal) a at the β point and in QoS communication with the base station A finds the base station B as a handoff destination candidate base station. In this case, since the number of terminals using the QoS of the base station B is not known, the base station A is only notified that the reception sensitivity of the base station B is better than that of the base station A. Receiving this notification, the base station A transmits a traffic channel assignment (TrafficChannelAssignment; TCA) indicating that the base station B may be added to the handoff destination candidate to the terminal a, but the number of QoS using terminals of the base station B is In the case of the example shown in FIG. 15, the number is 7 and exceeds the “maximum guaranteed number when the assigned QoS rate = high” = 3 and the “maximum guaranteed number when the assigned QoS rate = medium” = 5 shown in FIG. Since it is busy, it tries to assign a low QoS rate to terminal a. Eventually, the terminal a, which is performing QoS communication with the base station A at the β point, for example, at a high QoS rate, the base station B has entered the handoff destination candidate. QoS communication is performed at the rate, and the transfer rate decreases.

A first object of the present invention is to provide a base station capable of notifying a wireless communication terminal of information related to the traffic status of QoS communication of neighboring base stations that can be handoff destination candidates.
A second object of the present invention is to provide a wireless communication terminal capable of acquiring information on the traffic status of QoS communication of neighboring base stations that can be handoff destination candidates.
The present invention provides a communication control method capable of performing QoS communication with a base station handed off at a QoS rate as high as possible by a wireless communication terminal that has acquired information on the traffic status of QoS communication of neighboring base stations that can be handoff destination candidates. Is the third purpose.

  In order to achieve the first object, the base station according to claim 1 informs the wireless communication terminal that is performing the QoS communication of information related to the traffic status of the QoS communication of the neighboring base station that can be a handoff destination candidate. And receiving means for receiving a notification of a neighboring base station that can be a handoff destination candidate of the wireless communication terminal from the wireless communication terminal performing the QoS communication.

  In order to achieve the second object, the wireless communication terminal according to claim 2 includes information holding means for holding information on neighboring base stations that can be handoff destination candidates, and broadcast information received from a base station that is performing QoS communication. Information acquisition means for acquiring information on the traffic status of QoS communication of neighboring base stations that can be the handoff destination candidate, information on the traffic status of QoS communication acquired by the information acquisition means, and the periphery that can be the candidate for handoff destination Based on the received field strength of the base station, each of the neighboring base stations that can be handoff destination candidates is determined to be included in the handoff destination candidate base station, and determined to be included in the handoff destination candidate base station The base stations in the QoS communication are notified of the neighboring base stations that can be handoff destination candidates. Characterized by comprising a notification unit, a.

  The information related to the traffic status of the QoS communication may be the number of wireless communication terminals that are communicating using the QoS of the neighboring base station or the number of wireless communication terminals that can communicate using the remaining QoS of the neighboring base station. It is preferable to provide a wireless communication terminal capable of acquiring information on the traffic status of QoS communication of neighboring base stations that can be handoff destination candidates.

  A base station that has been determined by the determination means to have a heavy traffic load for QoS communication over a certain period of time can be excluded from the search target of the handoff destination candidate, and the QoS communication traffic of neighboring base stations that can be handoff destination candidates This is preferable in providing a wireless communication terminal capable of acquiring information related to the situation.

  When it is determined that the traffic load of the QoS communication is improved by the determination unit at the end of the QoS communication, returning the base station excluded from the search target of the handoff destination candidate to the search target of the handoff destination candidate This is preferable in providing a wireless communication terminal capable of acquiring information related to the traffic status of QoS communication of neighboring base stations that can be candidates.

  In order to achieve the third object, a communication control method according to claim 6 holds information on neighboring base stations that can be handoff destination candidates, and performs the handoff based on broadcast information received from a base station during QoS communication. The information on the traffic status of the QoS communication of the neighboring base station that can be the destination candidate is acquired, and the handoff is performed based on the acquired information on the traffic status of the QoS communication and the received electric field strength of the neighboring base station that can be the handoff destination candidate. For each neighboring base station that can be a destination candidate, it is determined whether or not to include in the handoff destination candidate base station, and the neighboring base station that can be the handoff destination candidate determined to be included in the handoff destination candidate base station is the QoS. A notification is made to the communicating base station.

  The information related to the traffic status of the QoS communication may be the number of wireless communication terminals that are communicating using the QoS of the neighboring base station or the number of wireless communication terminals that can communicate using the remaining QoS of the neighboring base station. It is preferable to provide a communication control method in which a wireless communication terminal that has acquired information on the traffic status of QoS communication of neighboring base stations that can be handoff destination candidates can perform QoS communication with a base station that has handed off at the highest possible QoS rate.

  A base station that is determined to have a heavy traffic load for QoS communication over a certain period of time includes information on the QoS communication traffic status of neighboring base stations that can be a handoff destination candidate to be excluded from the handoff destination candidate search target. This is preferable in providing a communication control method in which the acquired wireless communication terminal can perform QoS communication with a base station handed off at the highest possible QoS rate.

  When it is determined that the traffic load of the QoS communication is improved at the end of the QoS communication, returning the base station excluded from the search target of the handoff destination candidate to the search target of the handoff destination candidate can be a handoff destination candidate. This is preferable in providing a communication control method in which a wireless communication terminal that has acquired information on the traffic status of QoS communication of neighboring base stations can perform QoS communication with a base station handed off at the highest possible QoS rate.

  According to the present invention, the wireless communication terminal can acquire information on the traffic status of the QoS communication of the neighboring base station that can be a handoff destination candidate from the base station that is performing the QoS communication. A wireless communication terminal that has acquired information on the traffic status of QoS communication can perform QoS communication with the base station at the highest possible QoS rate.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating the configuration of a base station 100 used in the mobile communication system according to the first embodiment of the present invention. FIG. 2 is a radio communication terminal used in the mobile communication system according to the first embodiment of the present invention. 2 is a block diagram showing the configuration of 200. FIG. The base station 100 according to the present embodiment performs data communication with a wireless communication terminal or another base station corresponding to a communication method of a CDMA2000 1x EV-DO communication method (hereinafter referred to as an EV-DO system) via an antenna 110. As for the communication system of CDMA2000 1x EV-DO, the CDMA2000 1x EV-DO Rev. 0 and CDMA2000 1x EV-DO Rev. A, or CDMA2000 1x EV-DO Rev. Only A is supported. In addition, the wireless communication terminal 200 according to the present embodiment can perform data communication with other wireless communication terminals and base stations corresponding to the communication method of the CDMA2000 1x EV-DO communication method (hereinafter referred to as EV-DO system). As for the CDMA2000 1x EV-DO communication system, the CDMA2000 1x EV-DO Rev. 0 and CDMA2000 1x EV-DO Rev. Both A are supported.

  As shown in FIG. 1, the base station 100 of the present embodiment includes an antenna 110, an EV-DO RF unit 130, an RF control unit 140, a system control unit 150, an input unit 160, a display unit 170, The system storage unit 180, the RF control unit 140 includes a reception unit 140a and a transmission unit 140b, the system control unit 150 includes a neighboring base station information notification unit 150a, and a notification information transmission unit. 150b, a notification receiving unit 150c, and a QoS control unit 150d. The system storage unit 180 includes a peripheral base station information storage unit 180a and a terminal-base station electric field strength storage unit 180b. Yes.

The RF unit for EV-DO 130 converts data transmitted by the EV-DO system into a high frequency signal and transmits it from the antenna 110, or converts data input from the antenna 110 into a high frequency signal. .
The RF control unit 140 controls the communication (transmission / reception) of the EV-DO system, and measures the strength (RSSI, etc.) of the electric field from the wireless communication terminal or other base station device (not shown) received by the antenna. It is something to do. Also, it functions as a reception unit 140a and a transmission unit 140b corresponding to the high-frequency signal input from the EV-DO RF unit 130 and the high-frequency signal output to the EV-DO RF unit 130. Also, a QoS setting request is received from the wireless communication terminal.

The system control unit 150 is a control unit that controls each unit of the base station 100 in an integrated manner.
The neighboring base station information reporting unit 150a broadcasts information on neighboring base stations (hereinafter also referred to as handoff destination candidate base stations) that can be handoff destination candidates (active sets) to wireless communication terminals that are performing QoS communication. Is.
The broadcast information transmitting unit 150b transmits broadcast information (QoS communication) to the wireless communication terminal that is performing QoS communication so that the wireless communication terminal that is performing QoS communication acquires information related to the traffic status of the QoS communication of the handoff destination candidate base station. Information on handoff destination candidate base stations broadcast from the base station 200 in operation) is transmitted.
The notification receiving unit 150c determines whether the wireless communication terminal performing the QoS communication is a handoff destination candidate based on the information on the traffic status of the QoS communication and the received signal strength indicator (RSSI) of the handoff destination candidate base station. A notification of a neighboring base station that can be the handoff destination candidate determined to be included in the base station is received.
The QoS control unit 150d performs QoS resource management including QoS resource allocation and QoS resource allocation for a radio communication terminal that is communicating with the base station and a radio communication terminal that requests QoS from the base station. The QoS rate is adjusted.

  The input unit 160 is used when inputting information or selecting one of the options displayed on the display screen of the display unit 170, and has various keys and various buttons. Note that the input unit 160 and the display unit 170 may be omitted as necessary.

The system storage unit 180 includes a memory such as a RAM, and stores application programs and temporary data.
The peripheral base station information storage unit 180a stores peripheral base station information of the base station.
The terminal-base station field strength storage unit 180b stores information on the field strength between the wireless communication terminal and the base station.

  As shown in FIG. 2A, the wireless communication terminal 200 according to the present embodiment includes an antenna 210, a DO RF unit 230, an RF control unit 240, a system control unit 250, an input unit 260, and a display unit 270. The system storage unit 280 and the like, and the RF control unit 240 includes a reception unit 240a and a transmission unit 240b. Further, as shown in FIG. 2B, the system control unit 250 includes an information acquisition unit 250a, a handoff destination candidate determination unit 250b, a handoff execution unit 250c, a notification unit 250d, a QoS rate estimation unit 250e, A system storage unit 280, a peripheral base station information storage unit 280a, a terminal-base station electric field strength storage unit 280b, a QoS using terminal number storage unit 280c, and a remaining QoS use It has a possible terminal number storage unit 280d and a QoS rate storage unit 280e.

The RF unit for EV-DO 230 converts data to be transmitted by the EV-DO system into a high-frequency signal and transmits it from the antenna 210, or converts data input from the antenna 210 into a high-frequency signal. .
The RF control unit 240 controls communication (transmission / reception) of the EV-DO system, and measures electric field strength (RSSI or the like) from a base station (not shown) received by the antenna 210. Further, it functions as a reception unit 240a and a transmission unit 240b in response to a high-frequency signal input from the EV-DO RF unit 230 and a high-frequency signal output to the EV-DO RF unit 230.

The system control unit 250 is a control unit that controls each unit of the wireless communication terminal 200 in an integrated manner.
The information acquisition unit 250a acquires information related to the QoS communication traffic status of the handoff destination candidate base station based on the broadcast information received from the base station in the QoS communication. As information on the traffic status of QoS communication of the neighboring base station, the number of wireless communication terminals (number of QoS using terminals) in communication using the QoS of the neighboring base station is used, or the remaining information of the neighboring base station is used. It is assumed that the number of wireless communication terminals that can communicate using QoS (the number of remaining QoS usable terminals) is used.
The handoff destination candidate determination unit 250b includes each of the handoff destination candidate base stations in the handoff destination candidate base station based on the acquired information on the traffic status of the QoS communication and the received electric field strength of the handoff destination candidate base station. Whether or not.
The handoff execution unit 250c actually performs handoff to the base station that has become the handoff destination candidate base station.
The notifying unit 250d notifies the base stations in the QoS communication of neighboring base stations that can be the handoff destination candidates determined to be included in the handoff destination candidate base stations.
The QoS rate estimation unit 250e estimates a QoS rate for each connectable base station from broadcast information (information of a handoff destination candidate base station broadcast from the base station 200 that is performing QoS communication).
The DRC determination unit 250f determines that the predicted communication speed for the handoff destination candidate base station is equal to or higher than the minimum communication speed corresponding to the currently set QoS rate or less than the minimum communication speed corresponding to the currently set QoS rate. Is determined based on DRC (Data Rate Control bit).

  The input unit 260 is used when inputting information or selecting one of the options displayed on the display screen of the display unit 270, and has various keys and various buttons. Note that the input unit 260 and the display unit 270 may be omitted as necessary.

The system storage unit 280 is configured by a memory such as a RAM, and stores application programs and temporary data.
The peripheral base station information storage unit 280a stores (holds) handoff destination candidate base station information.
The terminal-base station field strength storage unit 280b stores information regarding the field strength between the wireless communication terminal and the base station.
The QoS used terminal number storage unit 280c stores the number of wireless communication terminals in communication with the neighboring base station 200 using QoS.
The remaining QoS usable terminal number storage unit 280d stores the number of wireless communication terminals that can be communicated using the QoS remaining in the neighboring base station 200.
Note that both the QoS using terminal number storage unit 280c and the remaining QoS usable terminal number storage unit 280d may be provided, but only one of them may be provided according to the format of the broadcast information broadcast from the base station 200. It may be.
The QoS rate storage unit 280e stores a QoS rate for each connectable base station.

  Next, various processes performed by the wireless communication terminal with the base station in the mobile communication system of the present embodiment will be described with reference to FIGS.

[Handoff process 1]
FIG. 3 is a flowchart showing handoff processing 1 performed in the wireless communication terminal in the mobile communication system of the first embodiment. This handoff process 1 is a process that is performed when “the number of QoS using terminals of the base station” is included in the broadcast information from the communicating base station. First, in step S11, it is determined whether or not there is a handoff destination candidate base station. If there is a handoff destination candidate base station, the process proceeds to step S12, and if there is no handoff destination candidate base station, the process ends. In step S12, it is determined whether or not communication with the current base station is in use of QoS. If QoS is in use, the process proceeds to step S13, and if not in use, the process immediately proceeds to step S15. In step S13, the handoff destination candidate base station determines whether or not the number of QoS using terminals is equal to or less than a threshold value α. If the number of QoS using terminals is equal to or less than the threshold value α, the process immediately proceeds to step S15. If it exceeds α, the process proceeds to step S14. In step S14, it is determined whether the DRC for all communicable base stations is lower than the QoS minimum expected DRC. If the DRC for all communicable base stations is lower than the QoS minimum expected DRC, the process proceeds to step S15. If the DRC for all the communicable base stations does not fall below the QoS minimum expected DRC, the process ends. In step S15, a route update message (RouteUpdate Message) including the handoff destination candidate base station is transmitted to the communicating base station.

[Broadcast Information Available for Handoff Processing 1 (Part 1)]
The broadcast information shown in FIG. 4 is obtained by adding a “QoSATNum” field indicating the number of terminals currently connected to the base station and performing QoS communication (number of QoS using terminals) to the existing “QuickConfig Massage”. In the illustrated example, the number of QoS using terminals is represented by 6 bits, that is, the maximum number of QoS using terminals is 63.
[Broadcast Information Available for Handoff Processing 1 (Part 2)]
The broadcast information shown in FIG. 5 includes the number of terminals (the number of terminals using QoS) connected to the base station corresponding to the neighboring base station information included in the message to the existing “SectorParameters Massage” and performing QoS communication. In the illustrated example, the number of QoS using terminals is expressed by 6 bits, that is, the maximum number of QoS using terminals is 63.
[Broadcast Information Available for Handoff Processing 1 (Part 3)]
The broadcast information shown in FIG. 6 is newly created as “QosInformation Massage”, and is connected to a base station corresponding to a neighboring base station included in “SectorParameters Massage” and performs the QoS communication (QoS). In the illustrated example, the number of QoS used terminals is represented by 6 bits, that is, the maximum number of QoS used terminals is 63.
As broadcast information that can be used for the handoff process 1 described above, broadcast information (part 2) and broadcast information (part 3) can be used independently, but broadcast information (part 1) is used in combination with other broadcast information. It shall be.

  In the handoff process 1, (1) the base station includes in the broadcast information the number of terminals using QoS, which is information related to the traffic status of the QoS communication of neighboring base stations, and (2) the wireless communication terminal If a handoff destination candidate base station is found during communication using the base station, it is determined whether or not to include in the handoff destination candidate base station based on the broadcast information, and the neighboring base stations determined to be included in the handoff destination candidate base station Therefore, the wireless communication terminal is prevented from handing off to the base station with a large number of QoS using terminals and the QoS rate is lowered. Therefore, according to the handoff process 1, QoS communication with the base station can be performed at the highest possible QoS rate.

[Handoff process 2]
FIG. 7 is a flowchart showing handoff processing 2 performed in the wireless communication terminal in the mobile communication system of the first embodiment. This handoff process 2 is a process that is performed when the “number of remaining QoS usable terminals of the base station” is included in the broadcast information from the communicating base station. First, in step S21, it is determined whether or not there is a handoff destination candidate base station. If there is a handoff destination candidate base station, the process proceeds to step S22, and if there is no handoff destination candidate base station, the process ends. In step S22, it is determined whether or not communication with the current base station is in use of QoS. If QoS is in use, the process proceeds to step S23, and if not in use, the process immediately proceeds to step S25. In step S23, it is determined whether there is a remaining QoS usable terminal number at a QoS rate equal to or higher than the QoS rate currently used by the handoff destination candidate base station. If there is a remaining QoS usable terminal number, the process immediately proceeds to step S25. If there is no remaining QoS usable terminal, the process proceeds to step S24. In step S24, it is determined whether the DRC for all communicable base stations is lower than the QoS minimum expected DRC. If the DRC for all communicable base stations is lower than the QoS minimum expected DRC, the process proceeds to step S25. If the DRC for all the communicable base stations does not fall below the QoS minimum expected DRC, the process ends. In step S25, a route update message (RouteUpdate Message) including the handoff destination candidate base station is transmitted to the communicating base station.

[Broadcast Information Available for Handoff Process 2 (Part 1)]
The broadcast information shown in FIG. 8 includes the “NumQoS” field indicating the number of types of QoS supported by the base station and the QoS type indicated by the “NumQoS” field of the base station for the existing “QuickConfig Massage”. A “QoSRest” field indicating the number of terminals that can perform QoS communication with the remaining QoS (number of remaining QoS usable terminals) is added. In the illustrated example, the number of types of QoS is 6 bits (maximum value 63). The number of remaining QoS usable terminals corresponding to each QoS type is indicated by 0 bit or 5 bits (maximum value 31). Each QoS type is negotiated between the base station and the terminal by “KKQoS Request Massage” or the like.
[Broadcast Information Available for Handoff Process 2 (Part 2)]
The broadcast information shown in FIG. 9 includes the “NumQoS” field indicating the number of types of QoS supported by the base station and the QoS type indicated by the “NumQoS” field of the base station for the existing “SectorParameters Massage”. A “QoSRest” field indicating the number of terminals that can perform QoS communication with the remaining QoS (number of remaining QoS usable terminals) is added. In the illustrated example, the number of types of QoS is 6 bits (maximum value 63). The number of remaining QoS usable terminals corresponding to each QoS type is indicated by 0 bit or 5 bits (maximum value 31).
[Broadcast Information Available for Handoff Process 2 (Part 3)]
The notification information shown in FIG. 10 is newly created as “QosInformation Massage”.
As broadcast information that can be used for the handoff process 2 described above, broadcast information (part 2) and broadcast information (part 3) can be used alone, but broadcast information (part 1) is used in combination with other broadcast information. It shall be.

  In the handoff process 2, (1) the base station includes the number of remaining QoS usable terminals, which is information related to the traffic status of the QoS communication of the neighboring base stations, in the broadcast information, and (2) the wireless communication terminal When a handoff destination candidate base station is found during communication using QoS, based on the broadcast information, it is determined whether or not to include in the handoff destination candidate base station, and the periphery determined to be included in the handoff destination candidate base station Since only the base station information is notified to the base station, the wireless communication terminal is prevented from handing off to a base station with a large number of QoS using terminals and the QoS rate being lowered. Therefore, according to the handoff process 1, the wireless communication terminal can perform QoS communication with the base station at the highest possible QoS rate.

[Delete from search suggestions]
FIG. 11 is a flowchart showing a deletion process from search candidates performed in the wireless communication terminal in the mobile communication system according to the first embodiment. The deletion process from the search candidates is a process performed by the wireless communication terminal that is communicating with the base station. First, in step S31, it is determined whether or not communication with the current base station is in use of QoS. If QoS is in use, the process proceeds to step S32. If QoS is not in use, the process ends. In step S32, the presence / absence of a base station crowded with QoS is determined based on the broadcast information from the base station. If there is a base station crowded with QoS, the process proceeds to step S33. If there is no base station crowded with QoS, It ends as it is. Whether or not the base station is crowded with QoS can be determined by, for example, the strength of a pilot signal transmitted from the base station. In step S33, the base station determines whether or not QoS is crowded for a certain time (α time) or longer. If QoS is crowded for a certain time or longer, the process proceeds to step S34, and the base station is set as a handoff destination candidate base station. If the QoS is not crowded for a certain time or longer, the process is terminated.

[Restoration to search candidates]
FIG. 12 is a flowchart showing a restoration process to search candidates performed in the wireless communication terminal in the mobile communication system according to the first embodiment. The restoration process to the search candidate is a process performed by the wireless communication terminal that is communicating with the base station. First, in step S41, since QoS is crowded for a predetermined time or more due to the deletion process from the search candidates, it is determined whether or not there is a base station excluded from the search candidates of the handoff destination candidate base station. If so, the process proceeds to step S42, and if there is no base station excluded from the search candidates, the process ends. In step S42, it is determined whether or not to stop using the QoS. If the QoS of the base station is sufficient and the use of the QoS is continued, the process proceeds to step S43, and the QoS of the base station is crowded. If the use of is abandoned, the process immediately proceeds to step S45. In step S43, it is determined whether or not the QoS of the base station is available based on the broadcast information from the base station. If the QoS of the base station is available, the process proceeds to step S44, and the QoS of the base station is not available. If not, the process ends. In step S44, it is determined whether or not the base station QoS is free for a predetermined time (β time) or longer, and the base station QoS is free for a predetermined time (β time) or longer. If YES, the process proceeds to step S45. If the QoS of the base station is not available for a certain time (β time) or more, the process ends. In step S45, the base station is restored (added) as a search candidate for the handoff destination candidate base station.

  In the deletion process from the search candidate and the restoration process to the search candidate, (i) the wireless communication terminal is in a state where QoS is used and QoS is crowded for a certain time or more based on the broadcast information. If there is a base station, the base station is excluded from the search candidates for the handoff destination candidate base station, and (ii) the wireless communication terminal stops using QoS if there is a base station excluded from the search target in (i) above. Or when a certain time (β time) has passed since the QoS of the base station has been increased based on the broadcast information, the base station is returned to the search candidate of the handoff destination candidate base station. This prevents the communication terminal from handing off to a base station with a large number of QoS using terminals and lowering the QoS rate. Therefore, according to the deletion process from the search candidate and the restoration process to the search candidate, the wireless communication terminal can perform QoS communication with the base station at the highest possible QoS rate.

[Call processing 1]
FIG. 13 is a flowchart showing a transmission process 1 performed in the wireless communication terminal in the mobile communication system according to the first embodiment. This transmission process 1 is a process that is performed when the broadcast information from the base station includes “the number of terminals using QoS of the base station”. First, in step S51, it is determined whether or not QoS is to be used. If the QoS of the base station has a margin and QoS can be used, the process proceeds to step S52, and the QoS of the base station is crowded. For this reason, when QoS cannot be used, the process proceeds to step S53 to transmit to the base station having the highest DRC. In step S52, the QoS rate is estimated for each connectable base station based on the broadcast information from the base station. In the next step S54, the QoS rate is the highest among the base stations whose DRC exceeds the QoS minimum expected DRC. Send to a high base station.

[Call processing 2]
FIG. 14 is a flowchart showing outgoing call processing 2 performed in the wireless communication terminal in the mobile communication system of the first embodiment. This transmission process 2 is a process that is performed when the broadcast information from the base station includes “the number of remaining QoS usable terminals of the base station”. First, in step S61, it is determined whether or not QoS is to be used. If the QoS of the base station is sufficient and the QoS can be used, the process proceeds to step S62, and the QoS of the base station is crowded. For this reason, when QoS cannot be used, the process proceeds to step S63 to transmit to the base station having the highest DRC. In step S62, based on the broadcast information from the base station, for each connectable base station, the number of remaining QoS usable terminals among the base stations whose DRC exceeds the QoS minimum expected DRC is positive. Call the highest base station.

  In the transmission process 1 and the transmission process 2, the wireless communication terminal determines the base station of the transmission destination based on the broadcast information when performing transmission using QoS, so that the wireless communication terminal is a QoS using terminal. Transmission to a large number of base stations to prevent QoS communication at a low QoS rate is prevented. Therefore, according to the transmission process 1 and the transmission process 2, the wireless communication terminal can perform a transmission with a high possibility of performing QoS communication with the base station at a high QoS rate.

It is a block diagram which illustrates the structure of the base station used for the mobile communication system of 1st Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication terminal used for the mobile communication system of 1st Embodiment of this invention. It is a flowchart which shows the handoff process 1 implemented in the radio | wireless communication terminal in the mobile communication system of 1st Embodiment. It is a figure which illustrates the alerting | reporting information (the 1) which can be used for the handoff process 1 in the mobile communication system of 1st Embodiment. It is a figure which illustrates the alerting | reporting information (the 2) which can be used for the handoff process 1 in the mobile communication system of 1st Embodiment. It is a figure which illustrates the alerting | reporting information (the 3) which can be used for the handoff process 1 in the mobile communication system of 1st Embodiment. It is a flowchart which shows the handoff process 2 implemented in the radio | wireless communication terminal in the mobile communication system of 1st Embodiment. It is a figure which illustrates the alerting | reporting information (the 1) which can be used for the handoff process 2 in the mobile communication system of 1st Embodiment. It is a figure which illustrates the alerting | reporting information (the 2) which can be used for the handoff process 2 in the mobile communication system of 1st Embodiment. It is a figure which illustrates the alerting | reporting information (the 3) which can be used for the handoff process 2 in the mobile communication system of 1st Embodiment. It is a flowchart which shows the deletion process from the search candidate implemented in the radio | wireless communication terminal in the mobile communication system of 1st Embodiment. It is a flowchart which shows the restoration process to the search candidate implemented in the radio | wireless communication terminal in the mobile communication system of 1st Embodiment. It is a flowchart which shows the transmission process 1 implemented in the radio | wireless communication terminal in the mobile communication system of 1st Embodiment. It is a flowchart which shows the transmission process 2 implemented in the radio | wireless communication terminal in the mobile communication system of 1st Embodiment. It is a figure for demonstrating the handoff in the conventional mobile communication system. It is a figure which illustrates the QoS guarantee number table of the base station used for the handoff in the conventional mobile communication system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Base station 110 Antenna 130 EV-DO RF part 140 RF control part 140a Receiving part 140b Transmission part 150 System control part 150a Neighboring base station information alerting | reporting part 150b Broadcasting information transmitting part 150c Notification receiving part 150d QoS control part 160 Input part 170 Display unit 180 System storage unit 180a Peripheral base station information storage unit 180b Terminal-base station electric field strength storage unit 200 Wireless communication terminal 210 Antenna 230 RF unit for DO 240 RF control unit 240
240a receiving unit 240b transmitting unit 250 system control unit 250a information acquisition unit 250b handoff destination candidate determination unit 250c handoff execution unit 250d notification unit 250e QoS rate estimation unit 250f DRC determination unit 260 input unit 270 display unit 280 system storage unit 280a peripheral base station Information storage unit 280b Terminal-base station field strength storage unit 280c QoS used terminal number storage unit 280d Remaining QoS usable terminal number storage unit 280e QoS rate storage unit

Claims (9)

Information notifying means for notifying a wireless communication terminal that is performing QoS communication of information regarding the traffic status of QoS communication of a neighboring base station that can be a handoff destination candidate;
Receiving means for receiving a notification of a neighboring base station that can be a handoff destination candidate of the wireless communication terminal from the wireless communication terminal performing the QoS communication. Information holding means for holding information on neighboring base stations that can be handoff destination candidates;
Information acquisition means for acquiring information on the traffic status of QoS communication of neighboring base stations that can be handoff destination candidates based on broadcast information received from a base station in QoS communication;
Based on the information on the traffic status of QoS communication acquired by the information acquisition means and the received electric field strength of the neighboring base station that can be the handoff destination candidate, for each of the neighboring base stations that can be the handoff destination candidate, Determining means for determining whether to include in the station;
A wireless communication terminal comprising: notification means for notifying a base station in QoS communication of a neighboring base station that can be the handoff destination candidate determined to be included in the handoff destination candidate base station.   The information related to the traffic status of the QoS communication is the number of wireless communication terminals communicating using the QoS of the neighboring base station or the number of wireless communication terminals capable of communicating using the remaining QoS of the neighboring base station. The wireless communication terminal according to claim 2, wherein the wireless communication terminal is a wireless communication terminal.   4. The wireless communication terminal according to claim 2, wherein a base station determined to have a heavy traffic load of QoS communication over a predetermined time by the determination unit is excluded from search targets of the handoff destination candidates. 5. .   When the determination means determines that the traffic load of the QoS communication is improved at the end of the QoS communication, the base station excluded from the search target of the handoff destination candidate is returned to the search target of the handoff destination candidate. The wireless communication terminal according to claim 4. Holds information about neighboring base stations that can be handoff destination candidates,
Based on the broadcast information received from the base station in QoS communication, obtain information on the traffic status of QoS communication of neighboring base stations that can be the handoff destination candidate,
Whether each of the neighboring base stations that can be handoff destination candidates is included in the handoff destination candidate base station based on the acquired information on the traffic status of the QoS communication and the received electric field strength of the neighboring base station that can be the handoff destination candidate Determine whether or not
A communication control method, comprising: notifying a base station in the QoS communication of neighboring base stations that can be handoff destination candidates determined to be included in the handoff destination candidate base station.   The information related to the traffic status of the QoS communication is the number of wireless communication terminals communicating using the QoS of the neighboring base station or the number of wireless communication terminals capable of communicating using the remaining QoS of the neighboring base station. The communication control method according to claim 6, wherein:   The communication control method according to claim 6 or 7, wherein a base station determined to have a heavy traffic load for QoS communication over a predetermined time is excluded from search targets of the handoff destination candidates.   The base station excluded from the search target of the handoff destination candidate is returned to the search target of the handoff destination candidate when it is determined that the traffic load of the QoS communication is improved at the end of the QoS communication. The communication control method described in 1.

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