WO2007072934A1

WO2007072934A1 - Communication control method, radio communication terminal, and radio base station

Info

Publication number: WO2007072934A1
Application number: PCT/JP2006/325559
Authority: WO
Inventors: Yuji Kakuda
Original assignee: Kyocera Corporation
Priority date: 2005-12-22
Filing date: 2006-12-21
Publication date: 2007-06-28
Also published as: JP2007174309A; JP4832075B2

Abstract

A communication control method includes: a step of receiving a plurality of carriers from one radio base station by a radio communication terminal; a step of deciding whether to perform handoff to other radio base station by the radio communication terminal; and a step of successively requesting the radio base station to cut off the carrier up to a predetermined number of carries if the radio communication terminal performs handoff to the radio base station.

Description

Specification

Communication control method, radio communication terminal, and radio base station

Technical field

TECHNICAL FIELD [0001] The present invention relates to a multicarrier communication control method using a plurality of carriers, a radio communication terminal, and a radio base station.

Background art

[0002] In mobile communication networks using code division multiple access (CDMA), lxEV-DO (lx evolution-data only) that provides high-speed data communication is provided (for example, JP 2002-300644). See the official gazette).

[0003] In lxEV-DO, one carrier is assigned to one user (wireless communication terminal). In addition, the introduction of so-called “multi-carrier” (nxEV-DO), which realizes higher-speed data communication by assigning multiple carriers to one user, is also under consideration. Multicarriers are disclosed in Japanese Patent Application Laid-Open No. 2004-72459.

[0004] A multi-carrier mobile communication system will be described with reference to FIG. 1 and FIG. Hereinafter, in this specification, data communication refers to packet communication.

[0005] As shown in FIG. 1, in a multicarrier mobile communication system, one base station 200 (radio base station) is connected to one carrier. That is, the mobile terminal 100 (wireless communication terminal) uses a plurality of carriers (for example, 15 carriers) to connect to a plurality of base stations 200 # 1 to #n (for example, n = 15).

[0006] Also, as shown in FIG. 2, in a multicarrier mobile communication system, a packet control device 600 performs packet control for base stations 200 # l to #n. Specifically, in the downlink direction, packet control apparatus 600 allocates downlink packets from network 500 by distributing them to base stations 200 # 1 to # n (carriers lx to 15x). In the upstream direction, the packet controller 600 combines the upstream packets of base stations 200 # 1 to #n (carriers lx to 15x).

[0007] Through effective packet control, a wireless communication terminal can connect to a plurality of wireless base stations and perform packet communication using a plurality of carriers. Disclosure of the invention

[0008] In packet communication in the above-described multicarrier mobile communication system, a radio communication terminal is connected to a plurality of radio base stations at the time of handoff, and each radio communication terminal uses each of the radio communication terminals. Cut or set the carrier at the same time. Therefore, there is a problem that the processing load due to handoff control increases.

Therefore, the present invention has been made in view of the above points, and includes a communication control method, a wireless communication terminal, and a wireless base station that suppress processing load during handoff in a multi-carrier mobile communication system. The purpose is to provide.

[0010] In order to achieve the above object, a first feature of the present invention is a communication control method for controlling communication between a radio base station and a radio communication terminal by a multicarrier using a plurality of carriers, A step in which the radio communication terminal receives the plurality of carriers from one radio base station; a step of determining whether the radio communication terminal is capable of handing off to another radio base station; and the radio communication terminal When a terminal hands off to the other radio base station, the wireless communication terminal sequentially requests the one radio base station to disconnect the carriers up to a predetermined number of carriers, and the radio communication terminal The gist is to have a step of handing off to another radio base station.

[0011] According to the strong feature, in a multi-carrier using a plurality of carriers, it is not necessary to perform handoff control with a plurality of radio base stations by connecting a radio communication terminal to one radio base station. For this reason, the processing load at the time of handing off to another radio base station can be suppressed.

[0012] Further, when the wireless communication terminal performs handoff, by sequentially disconnecting a plurality of carriers, the processing load due to simultaneous disconnection of the plurality of carriers and simultaneous setting of the plurality of simultaneously disconnected carriers can be suppressed.

[0013] In the first aspect of the present invention, the wireless communication terminal further includes a step of sequentially adding the carriers used for the communication to the other wireless base stations at the time of the handoff. You may do it.

[0014] According to the strong feature, when the wireless communication terminal performs handoff, a plurality of carriers used for communication are sequentially added to the handoff destination wireless base station. Therefore, multiple keys The processing load due to simultaneous setting of the carrier can be suppressed.

[0015] A second feature of the present invention is a radio communication terminal that communicates with a radio base station by a multi-carrier using a plurality of carriers, and has a radio base station power receiving unit that receives the plurality of carriers. A handoff determining unit that determines whether or not to handoff to another radio base station, and when handing off to the other radio base station, the one radio base station disconnects the carrier up to a predetermined number of carriers. Thus, it is necessary to provide a carrier disconnection request unit that sequentially requests and a handoff control unit that hands off to the other radio base station.

[0016] In the second aspect of the present invention, it may further comprise a carrier setting unit that sequentially adds the carriers used for the communication to the other radio base stations at the time of the handoff.

[0017] A third feature of the present invention is a radio base station that communicates with a radio communication terminal by a multicarrier using a plurality of carriers, wherein the radio communication terminal is connected to another radio base station. The present invention includes a receiving unit that receives a node-off notification indicating handoff and a carrier cutting unit that sequentially disconnects the carriers up to a predetermined number of carriers when the handoff notification is received.

[0018] As described above, according to the present invention, it is possible to provide a communication control method, a radio communication terminal, and a radio base station that suppress the processing load during handoff in a multi-carrier mobile communication system.

Brief Description of Drawings

FIG. 1 is an overall schematic diagram of a conventional mobile communication system.

FIG. 2 is a diagram showing a packet flow in a conventional mobile communication system.

FIG. 3 is an overall schematic diagram of a mobile communication system according to an embodiment of the present invention.

FIG. 4 is a diagram showing a packet flow in the mobile communication system according to the embodiment of the present invention.

FIG. 5 is a functional block diagram of a radio communication terminal according to an embodiment of the present invention.

FIG. 6 is a carrier connection sequence in the mobile communication system according to the embodiment of the present invention. FIG. 7 is a handoff sequence (pattern 1) in the communication system according to the embodiment of the present invention.

FIG. 8 is a handoff sequence (pattern 2) in the communication system according to the embodiment of the present invention.

FIG. 9 is a handoff sequence (pattern 3) in the communication system according to the embodiment of the present invention.

FIG. 10 is a functional block diagram of a base station according to a modified example of the present invention.

FIG. 11 is a handoff sequence in a communication system according to a modified example of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0021] (Overall schematic configuration of mobile communication system)

FIG. 3 is an overall schematic configuration diagram of a mobile communication system according to an embodiment of the present invention.

[0022] The mobile communication system 10 provides high-speed packet communication (nxEV-DO) by multicarrier using a plurality of carriers.

The mobile communication system 10 includes a mobile terminal 100 (wireless communication terminal) and a plurality of base stations 200.

# 1 to 200 # n (radio base stations), a base station controller 300, a relay station 400, and a network 500. Note that the numbers of wireless communication terminals, base stations, and carriers included in the mobile communication system 10 are not limited to the numbers shown in FIG. The mobile terminal 100 may be a mobile phone, a wireless module, a card terminal, or the like.

[0024] Also, in the mobile communication system 10, the mobile terminal 100 is connected to only one of the base stations 200, and performs packet communication using a plurality of carriers (the maximum number of carriers allowed).

Specifically, in mobile communication system 10, as shown in FIG. 4, packets are transmitted and received. FIG. 4 is a diagram showing a packet flow in the mobile communication system 10.

[0026] As shown in FIG. 4, in the mobile communication system 10, a network 500 is provided in the downlink direction. The power downlink packet is transmitted from one base station 200 # 1 using the carriers lx to 15x via the relay station 400 and the base station controller 300.

On the other hand, the uplink packet from mobile terminal 100 in the uplink direction is transmitted to network 500 via base station 200 # 1, base station controller 300 and relay station 400 using carriers lx to 15x. Is done.

Here, an example in which a packet is transmitted and received using 15 carriers (carriers lx to 15x) is shown, but the number of carriers is not limited to 15. Also, the number of uplink carriers may be different from the number of downlink carriers.

[0029] In this way, in mobile communication system 10, since mobile terminal 100 connects to one base station 200 # 1 and performs packet communication, packet control is performed for a plurality of base stations 200 # l to #n. There is no need. Specifically, the packet control device distributes and assigns downstream packets to a plurality of base stations 200 # 1 to # n, or uplinks from a plurality of base stations 200 # 1 to # n in the upstream direction. There is no need to combine packets. This eliminates the need for capital investment for packet control devices.

[0030] (Functional block configuration of mobile terminal (wireless communication terminal))

The functional block configuration of mobile terminal 100 (wireless communication terminal) will be described with reference to FIG.

[0031] In the following, portions related to the present invention will be mainly described. Therefore, it has been noted that the mobile terminal 100 may be provided with a function block (such as a power supply unit) that is not shown in the figure or omitted in the description, which is essential for realizing the function as the device!

As shown in FIG. 5, mobile terminal 100 includes transmission / reception section 110, handoff event detection section 120, carrier control section 130, and handoff control section 140.

[0033] Transmission / reception section 110 transmits uplink packets assigned to a plurality of carriers to one base station 200 # 1 using the plurality of carriers.

[0034] Transmission / reception section 110 receives downlink packets respectively transmitted by a plurality of carriers from one base station 200 # 1.

[0035] As will be described later, when a handoff event is detected by the handoff event detection unit 120, the transmission / reception unit 110 transmits another base station 200 # 1 to another radio base station. A handoff notification indicating handoff may be transmitted.

The handoff event detection unit 120 determines to handoff based on the reception state of each carrier received by the transmission / reception unit 110.

[0037] Specifically, the handoff event detection unit 120 receives the RSSI (Received Signal) of each carrier.

Measure Strength Indicator). When the RSSI of each carrier of base station 200 # 1 in communication is below the threshold value, handoff event detector 120 determines to handoff to another base station. Note that the handoff event detection unit 120 may determine the handoff destination base station as the base station with the best communication state.

[0038] When the handoff event detection unit 120 determines to perform handoff, the carrier control unit 130 sequentially disconnects carriers up to a predetermined number of carriers with respect to the communicating base station 200 # 1. Request.

[0039] When carriers with base station 200 # 1 in communication are sequentially disconnected up to a predetermined number of carriers, carrier control section 130 may simultaneously disconnect the remaining carriers.

[0040] Carrier control section 130 may sequentially add carriers used for communication to base station 200 # n that is a handoff destination.

[0041] When the carrier control unit 130 disconnects all of the carriers with the base station 200 # 1 in communication, the handoff control unit 140 hands off to another base station.

[0042] (Operation of mobile communication system)

Next, the operation of the mobile communication system 10 described above will be described with reference to FIGS. Specifically, the following four operations (1) to (4) will be described. (1) Operation in which mobile terminal 100 connects to one base station 200 # 1 (carrier setting sequence). (2) Operation in which mobile terminal 100 communicating with base station 200 # 1 hands off to another base station 200 #n (node-off sequence (pattern 1)). (3) Operation in which mobile terminal 100 communicating with base station 200 # 1 hands off to another base station 200 # 2 and then hands off to another base station 200 # n (node, off-off sequence (pattern 2)) . (4) Operation in which mobile terminal 100 communicating with base station 200 # 1 hands off to another base station 200 #n (handoff sequence (pattern 3)).

[0043] (1) Carrier setting sequence

FIG. 6 shows a scenario in which the mobile terminal 100 sets up one base station 200 # 1 and multiple carriers. FIG.

As shown in FIG. 6, in step S 101, mobile terminal 100 transmits a Connection Req message for requesting carrier setting with base station 200 # 1.

[0045] In step S102, the base station 200 # 1 transmits a T-CH Assignment message for assigning a traffic channel (T-CH) to the mobile terminal 100.

[0046] In step S103, terminal authentication Z user authentication of the mobile terminal 100 is performed.

[0047] In step S104, the base station 200 # 1 and the mobile terminal 100 execute communication settings.

Then, packet communication is started using the set carrier lx.

[0048] In step S105 to step S107, mobile terminal 100 sets base station 200 # 1 and carrier 2x in the same manner as in the carrier lx setting step described above.

[0049] In step S108 to step S110, as in the carrier 2x setting step described above, mobile terminal 100 performs base station 200 # 1 and carrier 3x up to the maximum number of carriers allowed by mobile terminal 100 (for example, 15 carriers). Set ~ 15x.

[0050] (2) Handoff sequence (Pattern 1)

FIG. 7 is a sequence diagram when mobile terminal 100 in communication with base station 200 # 1 hands off to another base station 200 #n.

[0051] As shown in FIG. 7, in step S201, the mobile terminal 100 is connected to the base station 200 # 1 and performs packet communication using carriers lx to 15x.

[0052] In step S202, the mobile terminal 100 detects that a handoff event has occurred.

[0053] Specifically, if the RSSI of each carrier from the communicating base station 200 # 1 is less than or equal to the threshold, it is determined to handoff to another base station (in this case, the base station 200 # n) . Note that the mobile terminal 100 determines the handoff destination base station as the base station 200 with the best communication state.

[0054] In step S203, the mobile terminal 100 transmits a Connection Close message requesting to disconnect the carrier to the base station 200 # 1. Receiving the Connection Close message, base station 200 # 1 disconnects the carrier (for example, carrier 15x).

[0055] In step S204, the mobile terminal 100 determines that the base station 200 # 1 and the remaining carriers lx to l Packet communication is performed using 4x.

[0056] In step S205, the mobile terminal 100 uses the remaining carriers lx to 14x for the base station 200 # 1 up to a predetermined number of carriers (here, 1 carrier), as in the carrier 15x disconnection step. Cut sequentially.

[0057] In steps S206 to S207, as in the carrier disconnect step (step S203) described above, mobile terminal 100 transmits a Connection Close message to base station 200 # 1 to disconnect carrier lx.

Here, since all the carriers lx to 15x set between mobile terminal 100 and base station 200 # 1 have been disconnected, mobile terminal 100 determines that other base stations determined in step S202

Hand off to 200 # n.

[0059] In step S208, the mobile terminal 100 receives a Connection Req message for requesting carrier setting with the base station 200 #n.

In step S 209, base station 200 #n transmits a T-CH Assignment message for assigning a traffic channel (T-CH) to mobile terminal 100.

[0061] In step S210, the base station 200 # n and the mobile terminal 100 execute communication settings.

Then, packet communication is started using carrier lx set between base station 200 #n.

[0062] In step S211 to step S216, the mobile terminal 100 performs the base station 200 up to the maximum number of carriers allowed by the mobile terminal 100 (for example, 15 carriers) in the same manner as the carrier setting steps (steps S208 to S210) described above. # Set career for 1. Then, the mobile terminal 100 performs packet communication using the set carriers lx to 15x.

[0063] (3) Handoff sequence (Pattern 2)

FIG. 8 is a sequence diagram when mobile terminal 100 in communication with base station 200 # 1 hands off to another base station 200 # 2 and further hands off to another base station 200 #n.

[0064] As shown in FIG. 8, in step S301, the mobile terminal 100 is connected to the base station 200 # 1 and performs packet communication using carriers lx to 15x.

[0065] In step S302, the mobile terminal 100 performs a handoff event (base station 20 in communication).

0 # Detects that the RSSI of each carrier from 1 has occurred below the threshold). Then, mobile terminal 100 decides to handoff to another base station (in this case, base station 200 # 2). The

[0066] In steps S303 to S307, as in the carrier disconnection step (steps S203 to S207 in Fig. 7), the mobile terminal 100 assigns carriers lx to 15x to the base station 200 # 1 in a predetermined manner. Sequentially cut up to the number of carriers (here 1 carrier).

[0067] When all carriers lx to 15x set between mobile terminal 100 and base station 200 # 1 are disconnected, mobile terminal 100 moves to another base station 200 # 2 determined in step S302. Hand off.

[0068] In steps S309 to S313, similar to the above-described carrier setting step (steps S208 to S213 in Fig. 7), the mobile terminal 100 makes a carrier lx to 2x with the base station 200 # 2 as the handoff destination. Set. Then, mobile terminal 100 is set between base station 200 # 1 and performs packet communication using carriers lx to 2x.

[0069] In step S314, the mobile terminal 100 detects again that a handoff event (the RSSI of each carrier from the communicating base station 200 # 2 is equal to or less than a threshold value) has occurred. Then, the mobile terminal 100 decides to handoff to another base station (here, base station 200 #n).

[0070] In steps S315 to S317, as in the carrier disconnection step described above, the mobile terminal

100 causes base station 200 # 2 to sequentially disconnect carriers lx to 2x up to a predetermined number of carriers (here, 1 carrier).

[0071] When carriers lx to 2x set between mobile terminal 100 and base station 200 # 2 are all disconnected, mobile terminal 100 moves to another base station 200 #n determined in step S314. Hand off.

[0072] In steps S315 to S326, the mobile terminal 100 sequentially sets carriers lx to 15x with the base station 200 #n in the same manner as in the carrier setting step (S208 to S216 in FIG. 7). Packet communication is performed using the set carriers lx to 15x.

[0073] (4) Handoff sequence (Pattern 3)

FIG. 9 is a sequence diagram when mobile terminal 100 in communication with base station 200 # 1 hands off to another base station 200 #n. In such a handoff sequence, the mobile terminal 100 sequentially disconnects the carriers up to a predetermined number of carriers in order to prevent a decrease in throughput. Cut the remaining carriers at the same time. Also, mobile terminal 100 differs from (1) handoff sequence (pattern 1) in that it performs carrier setting for a predetermined number of carriers with the handoff destination after handoff.

[0074] As shown in FIG. 9, in step S401, mobile terminal 100 is connected to base station 200 # 1 and performs packet communication using carriers lx to 15x.

[0075] In step S402, the mobile terminal 100 performs a handoff event (the communicating base station 20).

0 # Detects that the RSSI of each carrier from 1 has occurred below the threshold). Then, the mobile terminal 100 determines to handoff to another base station (in this case, the base station 200 #n).

[0076] In steps S403 to S406, as in the carrier disconnection step described above, the mobile terminal

100 causes base station 200 # 1 to sequentially disconnect carriers lx to 15x up to a predetermined number of carriers (here, 3 carriers).

[0077] In step S407, the mobile terminal 100 transmits a Connection Close message of carriers lx to 3x having a predetermined number of carriers (3 carriers) to the base station 200 # 1, and carrier 1 Cut x ~ 3x at the same time.

Here, since all the carriers lx to 15x set between mobile terminal 100 and base station 200 # 1 have been disconnected, mobile terminal 100 determines that other base station 200 # n determined in step S402. Hand off to.

[0079] In step S408, the mobile terminal 100 transmits a ConnectionReq message requesting the setting of the carriers lx to 3x to the base station 200 # n that is the handoff destination.

[0080] In step S409, the base station 200 # n transmits a T-CH Assignment message for allocating a traffic channel (T-CH) to the mobile terminal 100, respectively.

[0081] In step S410, the base station 200 # n and the mobile terminal 100 execute communication settings.

Then, packet communication is started using the carriers lx to 3x set at the same time.

[0082] In step S411 to step S413, mobile terminal 100 sequentially sets base station 200 # 1 and carriers up to the maximum number of carriers allowed by mobile terminal 100 (for example, 15 carriers). Then, the mobile terminal 100 performs packet communication using the set carriers lx to 15x.

5o [0083] (Modification example)

Next, a modified example of the operation of the mobile communication system 10 will be described with reference to FIGS. The handoff sequence according to this modified example is different from the above-described handoff sequences (patterns 1 to 3) in that the mobile terminal 100 is led by the base station 200 that does not sequentially request disconnection of each carrier. In this modified example, differences from the above-described mobile communication system 10 will be mainly described.

[0084] First, with reference to FIG. 10, functional blocks of a base station 200 (radio base station) according to this modification will be described. Note that base stations 200 # l to 200 # n according to this modification all have the same functional block configuration.

[0085] In the following, the part related to this modification example will be mainly described. Therefore, it has been noted that the base station 200 may be provided with a function block (such as a power supply unit) that is not shown in the figure or omitted in explanation, which is essential for realizing the function as the device!

As shown in FIG. 10, base station 200 includes transmission / reception section 210 and carrier control section 220.

The transmission / reception unit 210 receives a handoff notification indicating that the mobile terminal 100 hands off to another base station 200.

[0088] When the transmission / reception unit 210 receives a handoff notification from the mobile terminal 100, the carrier control unit 220 sets the mobile terminal 100 and sequentially disconnects the carriers up to a predetermined number of carriers. Note that the carrier control unit 220 may sequentially cut the carriers up to a predetermined number of carriers and simultaneously cut the remaining carriers.

Next, referring to FIG. 11, mobile terminal 100 does not sequentially request disconnection of each carrier.

A handoff sequence performed by the base station 200 will be described.

FIG. 11 is a sequence diagram when mobile terminal 100 in communication with base station 200 # 1 hands off to another base station 200 #n.

[0091] As shown in FIG. 11, in step S501, mobile terminal 100 is connected to base station 200 # 1 and performs packet communication using carriers lx to 15x.

[0092] In step S502, the mobile terminal 100 determines that the handoff event (communication base station 20

0 # Detects that the RSSI of each carrier from 1 has occurred below the threshold). And move Terminal 100 decides to handoff to another base station (here, base station 200 #n).

[0093] In step S503, the mobile terminal 100 notifies the base station 200 # 1 that it will handoff to another base station (handoff notification).

[0094] In step S504, the base station 200 that has received the handoff notification from the mobile terminal 100

# 1 disconnects one of the carrier lx to 15x carriers configured with mobile terminal 100.

[0095] In steps S505 to S508, as in step S504, base station 200 # 1 sets mobile terminal 100 as a predetermined number of carriers (here, one carrier). Sequentially cut until.

[0096] When all carriers set between mobile terminal 100 and base station 200 # 2 are disconnected, mobile terminal 100 hands off to other base station 200 # n determined in step S502.

In steps S 509 to S 517, mobile terminal 100 sequentially sets carriers with base station 200 #n, and performs packet communication using the set carriers lx to 15x.

[0098] Also in the handoff sequence according to this modified example, as in the above-described handoff sequence (pattern 3), base station 200 sequentially disconnects carriers up to a predetermined number of carriers (for example, three carriers). The mobile terminal 100, which can disconnect the remaining carriers at the same time, may simultaneously set a predetermined number of carriers with the handoff destination after handoff.

[0099] (Action 'effect)

According to the mobile communication system according to an embodiment of the present invention, when a mobile terminal 100 is connected to one base station 200 in a multicarrier using a plurality of carriers, There is no need to perform handoff control. For this reason, the processing load at the time of handing off to another base station 200 can be suppressed.

[0100] Further, when mobile terminal 100 performs handoff, by sequentially disconnecting a plurality of carriers, the processing load due to simultaneous disconnection of the plurality of carriers and simultaneous setting of the plurality of simultaneously disconnected carriers can be suppressed.

[0101] According to the mobile communication system of one embodiment of the present invention, the mobile terminal 100 is a hand. When turning off, a plurality of carriers used for communication are sequentially added to the handoff destination base station 200. Therefore, the processing load due to simultaneous setting of a plurality of carriers can be suppressed.

[0102] According to the mobile communication system of one embodiment of the present invention, it is possible to suppress a decrease in throughput at the time of handoff by simultaneously setting a predetermined number of carriers.

[0103] (Other Embodiments)

As described above, the contents of the present invention have been disclosed through one embodiment of the present invention. 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 will be apparent to those skilled in the art.

[0104] For example, the functions of the above-described node off event detection unit 120, carrier control unit 130, and node off control unit 140 are provided as programs that can be executed by a communication device or a computer.

[0105] As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is determined only by the above-described specific features of the invention according to the scope of claims. The entire contents of Japanese Patent Application No. 2005-369839 (filed on Dec. 22, 2005) are incorporated herein by reference.

Industrial applicability

[0106] As described above, the communication control method, the radio communication terminal, and the radio base station according to the present invention can suppress the processing load at the time of handoff in a mobile communication system using multicarriers. This is useful in wireless communication such as body communication.

Claims

The scope of the claims

[1] A communication control method for controlling communication between a radio base station and a radio communication terminal by a multicarrier using a plurality of carriers,

A step in which the radio communication terminal receives the plurality of carriers from one radio base station;

A step in which the radio communication terminal determines whether to handoff to another radio base station;

When the wireless communication terminal hands off to the other wireless base station, the wireless communication terminal sequentially requests the one wireless base station to disconnect the carrier up to a predetermined number of carriers;

And a step of handing off the wireless communication terminal to the other wireless base station.

[2] The radio communication terminal further includes a step of sequentially adding the carriers used for the communication to the other radio base station at the time of the handoff. Communication control method.

[3] A wireless communication terminal that communicates with a wireless base station by a multicarrier using a plurality of carriers,

One radio base station power receiving unit that receives the plurality of carriers,

A handoff determining unit that determines whether or not to handoff to another radio base station; and when handing off to the other radio base station, the one radio base station is disconnected from the carrier up to a predetermined number of carriers. A wireless communication terminal comprising: a carrier disconnection requesting unit that sequentially requests, and a handoff control unit that performs handoff to the other radio base station.

[4] The radio according to claim 3, further comprising a carrier setting unit that sequentially adds the carriers used for the communication to the other radio base stations at the time of the handoff. Communication terminal.

[5] A radio base station that communicates with a radio communication terminal by a multicarrier using a plurality of carriers, A receiving unit that receives a node-off notification indicating that the wireless communication terminal is handing off to another wireless base station from the wireless communication terminal;

A radio base station, comprising: a carrier cutting unit that sequentially cuts the carriers up to a predetermined number of carriers when the handoff notification is received.