JP2015201780A - Radio communication terminal and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication terminal and a radio communication method, capable of suppressing throughput deterioration when scanning for another base station which becomes a handover destination.SOLUTION: A radio communication terminal 100 for scanning for another base station 302, which becomes a handover destination, while performing radio communication with a base station 300, includes: a plurality of radio communication units 102, 104 which performs radio communication with the base station 300; and a scan execution unit 110 which executes scanning. From among the plurality of radio communication units 102, 104, the scan execution unit 110 selects a radio communication unit 104 having a smallest communication amount, to execute scanning by the selected radio communication unit 104. The communication unit 102 which is not selected continues communication.

Description

  The present invention relates to a wireless communication terminal and a wireless communication method for scanning another base station that is a handover destination while performing wireless communication with a base station.

  There is a TDMA-TDD system as one of the representative systems of wireless communication such as PHS (TDMA: Time Division Multiple Access: TDD: Time Division Duplex). TDD is a method of subdividing a communication path on a time axis and switching between transmission and reception in a short time. TDMA is a method in which one frequency is subdivided on a time axis and communication is performed with a plurality of opponents. As communication standards using TDMA-TDD, there are PHS (Personal Handy phone System) and iBurst (registered trademark).

  In a PHS wireless communication system, a control channel (CCH: Control CHannel) and a plurality of base stations and wireless communication terminals arranged in a service area at the time of outgoing call, incoming call, location registration, etc. Communication is possible by transmitting and receiving a link channel (LCH: Link CHannel) and establishing a traffic channel (TCH: Traffic CHannel).

  In addition, when the communication state of the above system is established and communication is performed, and the communication state between the wireless communication terminal and the base station deteriorates due to the movement of the user, the wireless communication terminal performs handover to another base station. Do. Even when the wireless communication terminal is communicating with a certain base station, the wireless communication terminal scans another base station that can be a handover destination.

  The above-described scanning of the base station by the wireless communication terminal is performed by receiving the BCH transmitted by the base station. Therefore, when scanning the base station, the reception function of the wireless communication terminal is used. In particular, a base station scan for determining whether or not a handover is necessary during communication establishment is performed by interrupting the TCH. Therefore, if a scan of the base station is executed during communication establishment, the TCH cannot be used during the scan. As a result, the TCH is limited by the time for which the scan of the base station is executed, which causes a reduction in communication throughput.

  Patent Document 1 discloses a scan unit that scans surrounding base stations, a displacement amount calculation unit that calculates a displacement amount per unit time of a wireless communication terminal, and a calculated displacement amount per unit time that is a predetermined value or less. In this case, a wireless communication terminal including a scan stopping unit that does not execute scanning is disclosed. According to Patent Document 1, by providing a period during which base station scanning is not performed, wasteful power consumption associated with base station scanning is reduced, and base station scanning that determines whether or not handover is necessary particularly during communication establishment However, it is also possible to avoid a decrease in throughput caused by limiting the TCH.

JP 2010-81437 A

  However, in Patent Document 1, it is possible to avoid a decrease in throughput during a period in which scanning is not performed, but it is possible to avoid a decrease in throughput when scanning is performed (that is, when the terminal is moving greatly). Can not. Therefore, there is a demand for suppressing a decrease in throughput even when scanning is performed.

  In view of such a problem, an object of the present invention is to provide a wireless communication terminal and a wireless communication method that can suppress a decrease in throughput when scanning another base station that is a handover destination.

  In order to solve the above problems, a typical configuration of a wireless communication terminal according to the present invention is a wireless communication terminal that scans another base station that is a handover destination while performing wireless communication with a base station. A plurality of wireless communication units that perform communication and a scan execution unit that performs scanning are selected, and the scan execution unit selects a wireless communication unit with the smallest communication amount from the plurality of wireless communication units, and is selected A scan is performed by the radio communication unit, and the radio communication unit that is not selected continues communication.

  The scan execution unit may select a wireless communication unit having the smallest physical channel in communication as a wireless communication unit having the smallest communication amount from a plurality of wireless communication units.

  The scan execution unit may select a wireless communication unit having the smallest communication data rate as a wireless communication unit having the smallest communication amount from a plurality of wireless communication units.

  The scan execution unit may move the physical channel in communication of the selected wireless communication unit to an unused physical channel of the non-selected wireless communication unit before executing the scan.

  The scan execution unit may continue communication on a physical channel other than the physical channel necessary for receiving the broadcast channel.

  A representative configuration of a wireless communication method according to the present invention is a wireless communication method in which a wireless communication terminal scans another base station that is a handover destination while performing wireless communication with the base station. When the scan is executed, the wireless communication unit with the smallest communication amount is selected from the plurality of wireless communication units, the scan is executed, and the communication is continued for the wireless communication units that are not selected. It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the radio | wireless communication terminal and radio | wireless communication method which can suppress the throughput fall at the time of scanning the other base station used as a hand-over destination can be provided.

It is a block diagram which shows the structure of the radio | wireless communications system containing the radio | wireless communication terminal concerning 1st Embodiment. It is a channel block diagram explaining the transmission / reception timing of the radio | wireless communications system of FIG. It is a flowchart which shows operation | movement of the scan execution selection part of the scan execution part of FIG. It is a figure which shows an example of the throughput change of Downlink of the radio | wireless communication terminal of FIG. It is a flowchart which shows the modification of FIG. It is a block diagram which shows the structure of the radio | wireless communications system containing the radio | wireless communication terminal concerning 2nd Embodiment. It is a channel block diagram explaining the transmission / reception timing of the radio | wireless communications system of FIG. 7 is a flowchart illustrating an operation of the data channel moving unit of FIG. 6. It is a block diagram which shows the structure of the radio | wireless communications system containing the radio | wireless communication terminal concerning 3rd Embodiment. FIG. 10 is a channel configuration diagram illustrating transmission / reception timings of the wireless communication terminal of FIG. 9. 10 is a flowchart showing an operation of a scan execution selection unit in FIG. 9. 10 is a flowchart showing the operation of the timing processor unit of FIG. FIG. 10 is a diagram illustrating an example of Downlink throughput change of the wireless communication terminal of FIG. 9.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiment are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a wireless communication system 400 including a wireless communication terminal 100 according to the first embodiment. The wireless communication system 400 is a system that operates the TDMA-TDD system, and examples thereof include iBurst and PHS.

  As shown in FIG. 1, a wireless communication system 400 includes a wireless communication terminal 100, a base station 300 with which the wireless communication terminal 100 is currently performing wireless communication, and another base station 302 to be scanned by the wireless communication terminal 100. Including.

  In FIG. 1, only one other base station 302 to be scanned is shown to simplify the description. However, in practice, there are a plurality of other base stations to be scanned, and a scan is performed to receive the BCH channels of the plurality of base stations one by one, and one base station from the plurality of base stations Are selected as handover destination base stations.

  The wireless communication terminal 100 includes wireless communication units 102 and 104 that perform wireless communication with a base station (not shown) via an antenna 112, a scan execution unit 110 that performs scanning of another base station 302 that is a handover destination, Wireless communication control units 106 and 108 for controlling the wireless communication of the wireless communication units 102 and 104. Note that the wireless communication terminal 100 can perform communication at a speed of 1 Mbps per wireless communication unit, and can perform data transfer of 2 Mbps at both.

  As described below, the scan execution unit 110 includes a scan execution selection unit 114 that selects a radio communication unit with a small communication amount among the wireless communication units 102 and 104, and the wireless communication selected by the scan execution selection unit 114 Scan by part.

  Note that the present invention is not limited to the wireless communication terminal 100 including the two wireless communication units 102 and 104 and the wireless communication control units 106 and 108 as in the present embodiment, but includes three or more wireless communication units. The present invention is also applicable to a wireless communication terminal including a wireless communication control unit. In this case, the scan execution selection unit selects the wireless communication unit with the smallest communication amount from the plurality of wireless communication units.

  FIG. 2 is a channel configuration diagram showing transmission / reception timing of the wireless communication system 400 of FIG. In this embodiment, each base station includes four wireless communication units. In FIG. 2, an example of a frame of each wireless communication unit of the base station 300 that is communicating with the wireless communication terminal 100 is illustrated as a communication frame 200, and a frame of another base station 302 to be scanned is set as four communication frames 202. Illustrated.

  A frame by the two wireless communication units 102 and 104 of the wireless communication terminal 100 is illustrated as two communication frames 204. It is assumed that the upper communication frame corresponds to the wireless communication unit 102 and the lower communication frame corresponds to the wireless communication unit 104. The communication frame 204 indicates the transmission / reception timing at the normal time.

  The communication frame 206 exemplifies transmission / reception timing at the time of scanning in the first embodiment. A communication frame 206 of only the wireless communication unit selected as the wireless communication unit that executes scanning among the two communication frames is illustrated. The communication frame of the wireless communication unit that has not been selected is not shown in the figure because it does not change during normal scanning of the base station.

  The communication frames 200, 202, 204, and 206 are all set to 5 ms in all sections, and in each of the sections, there are three physical channels for transmission (Uplink data) and three physical channels for reception. (Downlink data). The communication frames 200, 202, 204, and 206 manage the first Uplink data and the first Downlink data as one set and manage it as one channel, and the second Uplink data and the second Downlink data. One set is managed as one channel, and the third Uplink data and the third Downlink data are managed as one channel as one set.

  Therefore, the communication frames 200 and 202 of the base stations 300 and 302 each include 12 physical channels (12 sets of Uplink data and Downlink data) of Channels 0 to 11, and Channel 9 is a BCH channel.

  Here, the communication frame 204 of the normal wireless communication terminal 100 will be described. The normal wireless communication terminal 100 indicates that the communication frame of the wireless communication unit 102 is the base of the two communication frames 204 as indicated by a thick solid line. Communicating with Channels 3, 10, 2 of the communication frame 200 of the station 300, the communication frame of the wireless communication unit 104 is communicating with Channel 8 of the communication frame 200 of the base station 300.

  Therefore, among the two communication frames 204, the communication frame of the wireless communication unit 102 uses three physical channels, whereas the communication frame of the wireless communication unit 104 uses only one physical channel and uses two physical channels. The physical channel is unused.

  FIG. 3 is a flowchart showing the operation (embodiment of the wireless communication method according to the present invention) of the scan execution selection unit 114 of the scan execution unit 110 of FIG. Hereinafter, the operation of the scan execution unit 110 will be described with reference to FIGS. 1 to 3.

  The scan execution unit 110 executes a scan for a base station that is a handover destination, for example, every 10 seconds. The scan execution selection unit 114 starts an operation every 10 seconds, for example, in order to select a wireless communication unit for executing a scan (step S100).

  The scan execution selection unit 114 that has started the operation counts the number of physical channels in communication of the wireless communication unit 102 and the wireless communication unit 104, respectively (step S102). Then, as described above, the wireless communication unit 102 has 3 physical channels in communication, and the wireless communication unit 104 has 1 physical channel in communication.

  Next, the scan execution selection unit 114 selects the wireless communication unit having the smallest number of physical channels in communication among the wireless communication units 102 and 104 (step S104). That is, the wireless communication unit 104 is selected.

  Thereafter, the scan execution selection unit 114 ends the operation, and the scan execution unit 110 executes a scan with the selected wireless communication unit 104 (step S106). As a result, the communication frame of the wireless communication unit 104 in the wireless communication terminal 100 illustrated in FIG. 2 does not perform channel 8 communication for one frame unlike the communication frame 206, and performs the scan (communication frame 202 of the base station 302. Of BCH channel).

  As described above, the selected wireless communication unit 104 executes the scan without performing communication with the connected base station 300 when executing the scan. However, since the wireless communication unit 104 with the smallest communication amount is used for executing the scan, and the other wireless communication unit 102 with a large communication amount continues to communicate, the missing communication amount is minimized.

  Therefore, the radio communication terminal 100 can suppress a decrease in throughput when scanning the handover destination base station.

  Note that the scan execution selection unit 114 selects the wireless communication unit 104 with the smallest physical channel in communication as the wireless communication unit with the smallest communication amount from the plurality of wireless communication units 102 and 104. In this case, since the scan execution selection unit 114 determines the amount of communication based on the number of physical channels, it can be easily and immediately selected.

  4 is a diagram illustrating an example of Downlink throughput change of the wireless communication terminal 100 of FIG. As shown in FIG. 4, the Downlink throughput of the wireless communication terminal 100 decreases every 10 seconds. This is accompanied by the scan execution of the scan execution unit 110. However, although the communication amount of 1/3 Mbps by the wireless communication unit 104 decreases, the communication amount of 1 Mbps by the wireless communication unit 102 is maintained. It can be seen that the drop in throughput can be suppressed because the amount of lost communication is minimized in this way.

  By the way, depending on the modulation method of communication, even if the number of physical channels is small, high-value modulation may have a larger communication amount (data transfer amount). Therefore, the amount of communication may be determined by the communication data rate.

  FIG. 5 is a flowchart showing a modification of FIG. The wireless communication system according to this modification is the same block diagram as the wireless communication system 400 shown in FIG.

  In this modification, the scan execution selection unit of the scan execution unit starts operation every 10 seconds, for example, in order to select a wireless communication unit every time the scan execution unit executes a scan, as in FIG. 3 (step S110). ). The scan execution selection unit that has started the operation calculates the sum of the communication data rates of the plurality of wireless communication units (step S112).

  Next, the scan execution selection unit selects a wireless communication unit having the smallest communication data rate from among the plurality of wireless communication units (step S114). Thereafter, the scan execution selection unit ends the operation, and the scan execution unit executes a scan with the selected wireless communication unit (step S116).

  According to such a scan execution selection unit, it is possible to make a determination that the amount of communication is substantially smaller by determining the amount of communication based on the communication data rate, and it is possible to reliably suppress a decrease in throughput.

(Second Embodiment)
FIG. 6 is a block diagram illustrating a configuration of a wireless communication system 402 including the wireless communication terminal 120 according to the second embodiment. In the present embodiment, the scan execution unit 130 of the wireless communication terminal 120 includes a scan execution selection unit 124 and a data channel moving unit 116. Since components other than the scan execution unit 130 have the same functions and configurations as those of the wireless communication system 400 illustrated in the first embodiment, the same reference numerals are given and description thereof is omitted.

  FIG. 7 is a channel configuration diagram illustrating transmission / reception timing of the wireless communication system 402 in FIG. In FIG. 7, the frames of the four wireless communication units of the base station 300 are illustrated as communication frames 210. The same applies to the base station 302 to be scanned, but the illustration is omitted.

  A frame corresponding to the two wireless communication units 102 and 104 of the wireless communication terminal 120 is illustrated as the communication frame 212. It is assumed that the upper communication frame corresponds to the wireless communication unit 102 and the lower communication frame corresponds to the wireless communication unit 104. The communication frame 212 indicates the normal transmission / reception timing before the data channel moving unit 116 of the scan execution unit 130 operates.

  A communication frame 214 indicates a communication frame after the data channel moving unit 116 operates. Note that each section of the physical channel and the communication frame, four frequencies, and the like are set to be the same as in the first embodiment. In addition, both communication frames 212 and 214 in FIG. 7 indicate a state before the scan execution unit 130 executes a scan.

  Here, the communication frame 212 of the wireless communication terminal 120 before the operation of the data channel moving unit 116 will be described. The wireless communication terminal 120 has a communication frame of the wireless communication unit 102 in communication with the channels 3 and 10 of the communication frame 210 of the base station 300 among the two communication frames 212, as indicated by a thick solid line. The communication frame communicates with Channels 7 and 8 of the communication frame 210 of the base station 300.

  Therefore, of the two communication frames 212, the communication frame of the wireless communication unit 102 uses the first and second physical channels, whereas the communication frame of the wireless communication unit 104 is A third physical channel is used.

  FIG. 8 is a flowchart showing the operation of the data channel moving unit 116 of FIG. Hereinafter, the operation of the data channel moving unit 116 will be described with reference to FIGS.

  First, the scan execution unit 130 starts the operation of the data channel moving unit 116 a few seconds before the scan of another base station 302 is executed (step S120). Thereafter, the data channel moving unit 116 counts the number of physical channels in communication of the wireless communication units 102 and 104 (step S122).

  As a result of counting the number of physical channels being communicated, a wireless communication unit with few physical channels being subjected to data communication is selected (step S124). However, in this embodiment, there are only two wireless communication units 102 and 104, and the number of physical channels during data communication is the same. In this case, whichever may be selected, it is assumed that the wireless communication unit 104 (the lower communication frame of the communication frames 212 of the wireless communication terminal 120 in FIG. 7) is selected.

  Thereafter, in order to move the physical channel during data communication from the communication frame of the selected wireless communication unit, an unused channel (an unused channel having the same time slot) corresponding to the physical channel in the communication frame of another wireless communication unit It is confirmed whether there is any (step S126).

  In the present embodiment, in addition to the wireless communication unit 104, the wireless communication unit that is the destination is only the wireless communication unit 102. As shown in FIG. 7, in the communication frame of the wireless communication unit 104, the third physical channel is a physical channel (Channel 8) in communication. On the other hand, the third physical channel of the wireless communication unit 102 is unused. Therefore, the third physical channel (Channel 8) of the communication frame of the wireless communication unit 104 has a destination.

  Note that the second physical channel (Channel 7) of the communication frame of the wireless communication unit 104 is also a physical channel in communication. However, since the second physical channel of the communication frame of the wireless communication unit 102 is also in communication, the second physical channel (Channel 7) of the communication frame of the wireless communication unit 104 has no destination.

  Therefore, the physical channel (Channel 8) of the communication frame of the wireless communication unit 104 is moved to the third physical channel of the wireless communication unit 102 (step S128). As a result of the movement, the communication frame of the wireless communication terminal 120 changes from the communication frame 212 to the communication frame 214.

  Note that the flowchart of FIG. 8 is applicable even when there are three or more wireless communication units. Therefore, when there are three or more wireless communication units, after executing steps S128 to S122 to S126 again as indicated by solid arrows, it is determined whether there is a wireless communication unit with the next smallest number of physical channels. Confirmation (step S132), if there is, the wireless communication unit is selected (step S134), and the operation of the data channel moving unit is terminated by repeating the operations after step S126 (step S130).

  However, in the case of the wireless communication terminal 120 of this embodiment, since there are only two wireless communication units 102 and 104, such an operation is unnecessary. Therefore, when the wireless communication terminal has only two wireless communication units, a flowchart as indicated by a dotted arrow is set in advance, and the operation of the data channel moving unit 116 is terminated after the operation of step S128 (step S130). ).

  After the operation of the data channel moving unit 116 is completed, the scan execution unit 130 causes the scan execution selection unit 124 to execute the operation shown in FIG. As a result, the execution selection unit 124 selects the wireless communication unit 104 with the smallest number of physical channels in communication, and the scan execution unit 130 performs a scan with the selected wireless communication unit 104. The selected wireless communication unit 104 executes scanning without performing communication with the connected base station 300 when performing scanning.

  As described above, according to the wireless communication terminal 120 of the present embodiment, the scan execution unit 130 determines that the physical channel in communication of the selected wireless communication unit 104 is not selected before performing the scan. The communication unit 102 is moved to an unused physical channel. Therefore, the scan execution is performed by the wireless communication unit 104 whose communication amount is reduced as much as possible in the physical channel during communication, and the other wireless communication unit 102 having a large communication amount continues to communicate. It is possible to reduce the number of communicating physical channels that sometimes cannot communicate.

(Third embodiment)
FIG. 9 is a block diagram illustrating a configuration of a wireless communication system 404 including the wireless communication terminal 150 according to the third embodiment. In the present embodiment, the scan execution unit 140 of the wireless communication terminal 150 includes a scan execution selection unit 134 and a timing processor unit 136. Since components other than the scan execution unit 140 have the same functions and configurations as those of the wireless communication system 400 illustrated in the first embodiment, the same reference numerals are given and description thereof is omitted.

  FIG. 10 is a channel configuration diagram illustrating transmission / reception timing of the wireless communication system 404 of FIG. The frames of the four wireless communication units of the base stations 300 and 302 are illustrated as communication frames 220 and 222, respectively.

  A frame corresponding to the two wireless communication units 102 and 104 of the wireless communication terminal 150 is exemplified as the communication frame 224. It is assumed that the upper communication frame corresponds to the wireless communication unit 102 and the lower communication frame corresponds to the wireless communication unit 104. However, these two communication frames 224 indicate the normal transmission / reception timing before the timing processor 136 of the scan execution unit 140 operates.

  The communication frame 226 is a communication frame that the scan execution unit 140 executes a scan. Note that each section of the physical channel and the communication frame, four frequencies, and the like are set to be the same as in the first embodiment.

  Here, the communication frame 224 of the wireless communication terminal 150 will be described. The wireless communication terminal 150 indicates that the communication frame of the wireless communication unit 102 of the two communication frames 224 is the communication frame 210 of the base station 300 as indicated by a thick solid line. Communication is performed at the same timing as Channels 3, 10, and 2, and a communication frame of the wireless communication unit 104 is communicating with Channels 7 and 8 of the communication frame 210 of the base station 300.

  Therefore, among the two communication frames 212, the communication frame of the wireless communication unit 102 uses the first, second, and third physical channels, whereas the communication frame of the wireless communication unit 104 is Only the second and third physical channels are used.

  FIG. 11 is a flowchart showing the operation of the scan execution selection unit 134 of FIG. FIG. 12 is a flowchart showing the operation of the timing processor unit 136 of FIG. Hereinafter, the operation of the scan execution unit 140 will be described with reference to FIGS. 9 to 12.

  As shown in FIG. 11, the scan execution unit 140 executes a scan of a base station that is a handover destination, for example, every 10 seconds. The scan execution selection unit 134 selects a wireless communication unit for executing a scan each time (step S140).

  The scan execution selection unit 134 that has started the operation counts the number of physical channels that the wireless communication unit 102 and the wireless communication unit 104 are communicating with (step S142). Then, as described above, the wireless communication unit 102 has 3 physical channels in communication, and the wireless communication unit 104 has 2 physical channels in communication.

  Next, the scan execution selection unit 134 selects the wireless communication unit having the smallest number of physical channels in communication among the wireless communication units 102 and 104 (step S144). That is, the wireless communication unit 104 is selected.

  Thereafter, the scan execution selection unit 134 ends the operation (step S146). As shown in FIG. 12, the scan execution unit 140 thereafter starts the operation of the timing processor unit 136 (step S148).

  First, the timing processor 136 calculates the distance between the wireless communication terminal 150 and the base station 300 in communication and the distance between the wireless communication terminal 150 and another base station 302 to be scanned (step S150). Next, the timing processor unit 136 calculates the difference between these distances (step S152).

  Next, the timing processor unit determines whether there is a physical channel in communication in the wireless communication unit 104 selected by the scan execution selection unit 134 in step S144 (step S154). As described above, the wireless communication unit 104 has two physical channels in communication.

  As shown in FIG. 10, when there is a physical channel in communication with the wireless communication unit 104 selected by the scan execution selection unit 134, the timing processor 136 before the start of Downlink 1 after the completion of Uplink 3 (that is, after transmission of Channel 8). Based on the distance difference calculated in step S152, the transmission / reception timing offset of the wireless communication unit 104 is changed (step S156).

  Thereafter, the wireless communication unit 104 performs a scan of receiving a BCH channel from the communication frame 222 of another base station 302 to be scanned by Downlink 1 (step S158). At this time, since the timing offset of the wireless communication unit 104 has been changed, it is possible to continue communication on physical channels other than the physical channel necessary for receiving the BCH channel (broadcast channel).

  For example, in the communication frame 226 of FIG. 10, Downlink 1 is a physical channel necessary for receiving the BCH channel, and the next Downlink 2 (Channel 7) is not communicable. However, the later Downlink 3 (Channel 8) can continue the communication, and the Uplinks 1 to 3 can all maintain the communication.

  Next, in order to return to the normal communication state after receiving the BCH channel, the timing offset changed by the timing processor unit 136 after the end of Downlink 3 is restored (step S160). Then, the operation of the timing processor unit 136 is terminated (step S162).

  In the communication frame 224 of FIG. 10, the selected wireless communication unit 104 has a physical channel for data communication. However, if there is no physical channel for data communication, step S164 is substituted for step S156 to step S160. Step S168 is executed.

  Specifically, the timing processor unit 136 changes the transmission / reception timing offset of the selected wireless communication unit 104 before the start of the communication frame 226 used for the scan of the base station 302 (before the start of Uplink 1) (step S164). . After that, the BCH channel of another base station 302 to be scanned is received (step S166).

  Next, in order to return to the normal communication state after receiving the BCH channel, the timing offset changed by the timing processor unit 136 is restored after the end of the communication frame 226 (after the end of Downlink 3) (step S168). Then, the operation of the timing processor unit 136 is terminated (step S162).

  That is, when there is no physical channel in communication in the selected wireless communication unit 104, it is not a problem if communication for one frame is disabled as it is, and therefore normal scanning is executed as in steps S164 to S168. That's what it means.

  According to the above configuration, the selected wireless communication unit 104 continues communication on physical channels other than the physical channel necessary for receiving the BCH channel (broadcast channel). Therefore, it is possible to further reduce the number of communicating physical channels that cannot communicate during scanning.

  Further, when another base station 302 to be scanned is located far away, the propagation delay in receiving the BCH channel increases. Therefore, although the timing correction amount of the timing processor unit 136 is large, the above-described timing change is possible because the time between Uplink3 and Downlink1 is also long.

  FIG. 13 is a diagram illustrating an example of Downlink throughput change of the wireless communication terminal 150 of FIG. As illustrated in FIG. 13, the Downlink throughput of the wireless communication terminal 150 decreases every 10 seconds. This is accompanied by the scan execution of the scan execution unit 140. However, the only decrease is 1/3 Mbps because Channel 7 cannot communicate. Thus, it can be seen that the decrease in throughput can be suppressed because the number of communicating physical channels that cannot communicate during scanning is reduced.

  Note that this embodiment can be combined with the second embodiment. For example, in the wireless communication terminal 150 shown in FIG. 9, the scan execution unit 140 can add the data channel moving unit 116 described in the second embodiment in addition to the scan execution selection unit 134 and the timing processor unit 136. It is.

  In this case, even if the physical channel still in communication remains after the data channel moving unit 116 moves the physical channel in communication, the number of physical channels that cannot be communicated at the time of scanning can be reduced, resulting in a combined effect. I can expect.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used as a wireless communication terminal and a wireless communication method for scanning another base station that is a handover destination while performing wireless communication with a base station.

DESCRIPTION OF SYMBOLS 112 ... Antenna, 116 ... Data channel moving part, 136 ... Timing processor part, 300 ... Base station, 302 ... Other base station, 100, 120, 150 ... Wireless communication terminal, 102, 104 ... Wireless communication part, 106, 108 ... Wireless communication control unit, 114, 124.134 ... Scan execution selection unit, 400, 402, 404 ... Wireless communication system, 110, 130, 140 ... Scan execution unit, 200, 202, 204, 206, 210, 212, 214 ... communication frame

Claims (6)

In a wireless communication terminal that scans another base station that is a handover destination while performing wireless communication with a base station,
A plurality of wireless communication units for performing wireless communication with the base station;
A scan execution unit for executing the scan,
The scan execution unit selects a wireless communication unit with the least communication amount from the plurality of wireless communication units, executes the scan by the selected wireless communication unit,
The wireless communication terminal, which is not selected, continues communication.   The scan execution unit selects a wireless communication unit having the smallest physical channel in communication as the wireless communication unit having the smallest communication amount from the plurality of wireless communication units. Wireless communication terminal.   2. The wireless communication unit according to claim 1, wherein the scan execution unit selects a wireless communication unit having the smallest communication data rate as the wireless communication unit having the smallest communication amount from the plurality of wireless communication units. Communication terminal.   The scan execution unit moves a physical channel in communication of the selected radio communication unit to an unused physical channel of an unselected radio communication unit before executing a scan. Item 3. A wireless communication terminal according to Item 2.   5. The wireless communication terminal according to claim 2, wherein the scan execution unit continues communication on a physical channel other than a physical channel necessary for receiving a broadcast channel. 6. In a wireless communication method in which a wireless communication terminal scans another base station that is a handover destination while performing wireless communication with a base station,
The wireless communication terminal includes a plurality of wireless communication units, and when performing a scan, the wireless communication unit having the smallest communication amount is selected from the plurality of wireless communication units, and the scan is performed. A wireless communication method characterized in that the wireless communication unit continues communication.

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