JP4336883B2 - Wireless LAN handover processing method - Google Patents

Description

  The present invention relates to a wireless LAN handover processing method, and in particular, when a reception level becomes weak, by performing parallel processing in a time-sharing manner of scan processing of neighboring wireless LAN base stations, the mobile terminal itself can be transferred to another wireless LAN base station having a high reception level. The present invention relates to a wireless LAN handover processing method for handover.

  In general, a wireless LAN terminal has only one receiver. While the wireless LAN terminal and the wireless LAN base station are communicating, information on neighboring base stations cannot be obtained, so the wireless LAN base station is switched. In other words, in the case of handover, the wireless LAN base station to which the wireless LAN terminal belongs recognizes that the attribution has been canceled because the signal from the wireless LAN base station does not reach, and searches for neighboring wireless LAN base stations from that point in time. This is a passive handover process to be performed.

  That is, it takes time to recognize that the wireless LAN terminal has been de-assigned, and after that, it is not always possible to hand over to a wireless LAN base station having a stable communication path that provides the strongest received signal level.

  For this reason, it takes time for switching at the data link layer, and performing a handover again increases the possibility of a timeout occurring in the upper layer application. Therefore, there is a high possibility that communication between the end-to-end between the wireless LAN terminal and the wired terminal is interrupted. On the other hand, if a plurality of receivers are mounted on a wireless LAN terminal, there is a high possibility that end-to-end communication will not be interrupted during handover. However, the size and power consumption of the wireless LAN card mounted on the wireless LAN terminal are increased, and use while moving is limited.

  If the wireless LAN terminal switches the transmission / reception of frames with the wireless LAN base station and the scanning process of the received signal level from the surrounding wireless LAN base station at the time of handover in a time division manner, the handover processing time can be obtained even in the state of one receiver. Can be shortened.

  The conventional wireless LAN handover processing method searches all other base stations that can communicate while maintaining the communication state with the base station connected during a call, and always has the highest measured electric field strength at the time of searching. The base station with the best communication state is selected and connected (for example, see Patent Document 1).

  In addition, while maintaining a call with a base station that is in a call, search for a downlink control channel signal of a neighboring base station, search for a downlink control channel signal of a neighboring base station when the reception level decreases, and re-synchronize (for example, (See Patent Document 2).

Japanese Patent Laying-Open No. 2001-231064 (page 2-4, FIG. 4) Japanese Patent Laid-Open No. 11-004470 (page 2-5)

  In the conventional wireless LAN handover processing method described above, the wireless LAN terminal has only one receiver. For this reason, information on neighboring base stations cannot be obtained while the wireless LAN terminal and the wireless LAN base station are communicating. In the case of handover, it is a passive method that recognizes that the attribution is canceled when the signal from the belonging wireless LAN base station does not reach and searches for neighboring wireless LAN base stations from that point. Handover processing.

  That is, a predetermined time is required until it is recognized that the wireless LAN terminal has been released, and after that, it is not always possible to hand over to a wireless LAN base station having a stable communication path that provides the strongest received signal level. Therefore, there is a disadvantage that communication is interrupted.

  If a plurality of receivers are mounted on a wireless LAN terminal, there is a high possibility that end-to-end communication will not be interrupted during handover, but the size and consumption of the wireless LAN card mounted on the wireless LAN terminal will increase. There is a disadvantage that the power is increased and the use while moving is limited.

  It is an object of the present invention to actively start handover processing when a wireless LAN terminal has a weak received signal level, and to time-divide data transmission / reception processing and scan processing of received signal levels of neighboring wireless LAN base stations. The wireless LAN hand that shortens the wireless LAN base station switching time and secures the most stable wireless communication path by executing a handover to another wireless LAN base station having a higher received signal level while performing in parallel To provide an over-processing method.

The first wireless LAN handover processing method of the present invention is:
A plurality of wireless LAN base stations and at least one wireless LAN terminal that is located and moves under each of the plurality of wireless LAN base stations,
When the reception level of the wireless LAN terminal becomes weak , the scan time is set based on the reception signal level, and the data transmission / reception processing and the scanning processing of the reception signal level of the surrounding wireless LAN base station are time-shared. And switching to the wireless LAN base station having a strong reception level.

The second wireless LAN handover processing method of the present invention is:
A wireless LAN terminal located under one of a plurality of wireless LAN base stations,
When the received signal level becomes weak , the scan time is set based on the received signal level, and the data transmission / reception process and the scan process of the received signal level of the surrounding wireless LAN base station are performed in time division in parallel. The wireless LAN base station has a strong reception signal level.

The third wireless LAN handover processing method of the present invention is:
A plurality of wireless LAN base stations and at least one wireless LAN terminal that is located and moves under each of the plurality of wireless LAN base stations,
The wireless LAN terminal includes a wireless part transceiver unit for performing communication in a wireless section, a reception signal level management part for managing a reception signal level of a peripheral wireless LAN base station input from the wireless part transceiver part, and the reception signal A handover processing unit that determines the necessity of the handover process based on the level, and a request to switch between the inter-station communication and the process of scanning the reception signal level of the surrounding wireless LAN base station according to an instruction of the handover processing unit. The scan processing switching unit that outputs to the radio unit transmitting / receiving unit and the scan processing time preset based on the received signal level by the handover processing unit are monitored, and the monitoring result is notified to the scan processing switching unit And an internal counter.

The fourth wireless LAN handover processing method of the present invention is:
A wireless LAN terminal located under one of a plurality of wireless LAN base stations,
A wireless unit transceiver unit for performing communication in a wireless section, a received signal level management unit for managing received signal levels of peripheral wireless LAN base stations input from the wireless unit transceiver unit, and a hand based on the received signal level A handover processing unit for determining the necessity of over processing, and a request for switching between inter-station communication and processing for scanning received signal levels of neighboring wireless LAN base stations according to an instruction from the handover processing unit to the wireless unit transmission / reception unit A scan process switching unit for outputting, and an internal counter for monitoring a scan processable time set in advance based on a received signal level by the handover processing unit and notifying the scan process switching unit of a monitoring result It is characterized by that.

According to a fifth wireless LAN handover processing method of the present invention, in the third wireless LAN handover processing method,
The received signal level manager is
By centrally managing the received signal level from the wireless LAN base station to which it belongs and the wireless LAN base station existing in the vicinity and the MAC address of each wireless LAN base station by receiving the beacon signal via the wireless unit transceiver unit The received signal level from the first and second wireless LAN base stations and the MAC address are stored in a table from the received beacon signal, and the first wireless LAN base station to which the first always belongs is 1 The information on the second wireless LAN base stations in the vicinity is sorted in descending order of the received signal level and stored in the second and later.

The sixth wireless LAN handover processing method of the present invention is the third or fifth wireless LAN handover processing method,
The handover processor is
It is determined whether or not the received signal level from the first wireless LAN base station to which it belongs belongs to a sufficient quality, notifies the scan process switching unit of the scan process start and scan process end, Switch the wireless LAN base station by comparing and judging the strongest wireless LAN base station among the received signal levels of the LAN base station and the received signal level from the first wireless LAN base station to which the wireless LAN terminal belongs. It is characterized by performing processing.

A seventh wireless LAN handover processing method of the present invention is the wireless LAN handover processing method according to any one of the third to sixth,
The scan processing switching unit
Upon receiving notification of the start of scanning processing from the handover processing unit, instructs the wireless unit transmitting / receiving unit to start scanning the beacon signal of the neighboring wireless LAN base station, and requests switching of the wireless LAN base station In response to the notification of the end of the scanning process from the handover processing unit, the wireless unit transmitting / receiving unit is requested to switch to end the scanning.

The eighth wireless LAN handover processing method of the present invention is the wireless LAN handover processing method according to any one of the fourth to seventh aspects,
The internal counter is
A scan processing time preset in the handover processing unit is monitored.

The ninth wireless LAN handover processing method of the present invention provides:
The wireless LAN terminal includes a first wireless LAN base station, a second wireless LAN base station, and a wireless LAN terminal that moves while belonging to the first wireless LAN base station, and the wireless LAN terminal performs communication in a wireless section. A radio unit transceiver unit, a received signal level management unit that manages received signal levels of neighboring wireless LAN base stations, a handover processing unit that determines the necessity of handover processing based on the received signal level, Wireless LAN handover processing method for a wireless LAN system having a scan processing switching unit that switches between inter-station communication and processing for scanning received signal levels of neighboring wireless LAN base stations, and an internal counter that monitors the scan processable time Because
A first monitoring step in which the wireless LAN terminal monitors the received signal level of the first wireless LAN base station to which the wireless LAN terminal belongs by the received signal level management unit;
The received signal level management unit scans the received signal level of the first wireless LAN base station to which the received signal level belongs, and outputs a scan result to the handover processing unit. A first comparison and determination step of determining whether or not the received signal level of the base station is a value sufficient to perform communication by comparing with a preset value;
When the reception signal level of the first wireless LAN base station is a reception signal level sufficient for communication, the process returns to the first monitoring step, and when the reception signal level is not sufficient for communication, The handover processing unit notifies the scan processing switching unit of the start of the scan processing, notifies the internal counter of the scan processing time based on the received signal level, and notifies the radio unit transmitting / receiving unit of the peripheral A scan process start step for outputting a switching command to scan information from a beacon signal from a wireless LAN base station and starting a scan process;
After starting the scanning process, the reception signal levels of the first wireless LAN base station and the second wireless LAN base station are scanned from the beacon signal, and the reception signal level management unit collects the scan information and belongs to it. A second signal level monitoring step of monitoring a received signal level of the first wireless LAN base station and a received signal level of the second wireless LAN base station;
When the received signal level of the second wireless LAN base station is stronger than the received signal level of the first wireless LAN base station, the handover processing unit notifies the scan processing switching unit of the end of scanning processing, and the wireless A scan process end step for instructing the unit transceiver unit to end the scan process;
After completion of the scan in the scan processing end step, the second comparison returns to the first signal level monitoring step again when the received signal level is compared and judged and the received signal level of the first wireless LAN base station is sufficient A decision step;
If the received signal level of the second wireless LAN base station is stronger than the received level of the first wireless LAN base station in the second comparison and determination step, the wireless LAN terminal sends the first wireless LAN. An attribution cancellation step of transmitting an attribution cancellation request to the base station and canceling the attribution with the first wireless LAN base station;
An attribution step belonging to the second wireless LAN base station by transmitting an attribution request from the wireless LAN terminal to the second wireless LAN base station;
And a wireless LAN handover processing method.

The tenth wireless LAN handover processing method of the present invention comprises:
A determination step of determining whether a sufficient received signal level is obtained from the wireless LAN base station in communication;
A scan process start step for setting a scan time based on the received signal level and starting a scan process for the neighboring wireless LAN base stations when it is determined that the sufficient received signal level is not obtained;
A received signal comparing step of comparing received signal levels from the neighboring wireless LAN base stations during the scanning process;
An attribution request step of transmitting an attribution request to a wireless LAN base station determined to have obtained a stronger received signal level in the received signal comparison step among the neighboring wireless LAN base stations;
And a wireless LAN handover processing method.

  The wireless LAN handover processing method of the present invention constantly monitors the received signal level while the wireless LAN terminal keeps belonging to the wireless LAN base station, and restricts data transmission and reception when it is determined that the received signal level is not of sufficient quality. . At this time, scanning of received signal levels from other neighboring base stations is started, and a neighboring base station with a stronger signal can be found and handed over. For this reason, there is an effect that the time required for the handover process of the wireless LAN terminal can be greatly shortened.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of a wireless LAN handover processing method of the present invention.

  This embodiment shown in FIG. 1 includes a wireless LAN base station 101, a wireless LAN base station 102, a wireless LAN terminal 103 that is located and moves under these wireless LAN base stations, a wireless LAN base station 101, and a wireless LAN. It comprises a wired terminal 104 existing on a wired LAN 105 behind which the base station 102 is connected.

  FIG. 2 is a block diagram showing details of the wireless LAN terminal of FIG.

  2 corresponding to the components shown in FIG. 1 are denoted by the same reference numerals or symbols, and the description thereof is omitted.

  Referring to FIG. 2, the wireless LAN terminal 103 includes a wireless unit transmitting / receiving unit 1031 for performing communication in a wireless section, a received signal level managing unit 1032 for managing received signal levels of neighboring base stations, and a received signal level. The handover processing unit 1033 for determining the necessity of the handover process, the scan processing switching unit 1034 for switching the process of scanning the received signal level of the end-end communication and the surrounding wireless LAN base station, and the scan processing time. And an internal counter 1035 for monitoring.

  Here, the scan processing time indicates a processing time for the wireless LAN terminal to detect a received signal from a surrounding wireless LAN base station.

  FIG. 3 is a diagram illustrating a MAC address table included in the received signal level management unit of FIG.

  Referring to FIG. 3, the received signal level from the wireless LAN base station is stored as a table in a built-in memory (not shown) corresponding to the MAC (Media Access Control) address of each wireless LAN base station. . Here, the MAC address indicates an address in which a destination address and a source address are assigned in the MAC layer.

  Returning to FIG. 2, the received signal level management unit 1032 of the wireless LAN terminal 103 receives the beacon signal from the wireless unit transmitting / receiving unit 1031 from the wireless LAN base station to which it belongs and the wireless LAN base stations existing in the vicinity. The received signal level and the MAC address of each wireless LAN base station are centrally managed.

  That is, the received signal level management unit 1032 stores the received signal level from the wireless LAN base stations 101 and 102 and the corresponding MAC address in the table from the received beacon signal. The wireless LAN base station 101 to which it belongs is always stored first, and the information of the neighboring wireless LAN base stations 102 is sorted in descending order of the received signal level and stored in the second and later. Therefore, secondly, information on wireless LAN base stations having a high received signal level among neighboring wireless LAN base stations is included. In this case, information of the wireless LAN base station 101 is stored first, and information of the wireless LAN base station 102 is stored second.

  The handover processing unit 1033 determines whether or not the received signal level from the wireless LAN base station 101 to which it belongs belongs to a sufficient quality, and notifies the scan processing switching unit 1034 of the start of scan processing and the end of scan processing. . A value for determining whether or not sufficient quality is maintained is determined by a preset parameter. The wireless LAN base station having the strongest reception signal level of the peripheral wireless LAN base station is compared with the signal from the wireless LAN base station to which the wireless LAN terminal 103 belongs, and processing related to switching of the wireless LAN base station is performed. Do.

  The scan processing switching unit 1034 receives the notification of the start of the scanning process from the handover processing unit 1033 and switches the wireless LAN base station to the wireless unit transmitting / receiving unit 1031 so as to scan the beacon signal of the neighboring wireless LAN base station. Request.

  Also, the scan process switching unit 1034 receives a notification of the end of the scan process from the handover processing unit 1033, and requests the radio unit transmitting / receiving unit 1031 to switch to end the scan.

  The internal counter 1035 monitors a scan processing time T1 preset in the handover processing unit 1033.

  FIG. 4 is a flowchart showing an operation procedure of the handover process of FIG.

  Next, the operation of the present embodiment will be described in more detail with reference to FIG. 1, FIG. 2, FIG. 3, and FIG.

  The operation when the wireless LAN terminal 103 moves from the wireless LAN base station 101 to which it belongs to the wireless LAN base station 102 and is handed over from the wireless LAN base station 101 to the wireless LAN base station 102 is shown below with reference to FIG. .

  The reception signal level of the wireless LAN base station 101 to which the wireless LAN terminal 103 belongs is output to the reception signal level management unit 1032 through the wireless unit transmission / reception unit 1031 of FIG. 2, and the reception signal level is monitored (step S1).

  Next, the received signal level management unit 1032 scans the received signal level of the assigned wireless LAN base station 101 at a constant interval T2, and outputs the scan result to the handover processing unit 1033. The value of the constant interval T2 is given as a preset parameter. Therefore, it is determined whether or not the received signal level of the wireless LAN base station 101 is a sufficient value for communication. If the received signal level is sufficient, the process returns to step 1; otherwise, the process proceeds to the next step (step S2).

  When the received signal level of the wireless LAN base station 101 is not a received signal level sufficient for communication, the handover processing unit 1033 notifies the scan processing switching unit 1034 of the start of the scanning process. When the handover processing unit 1033 of the wireless LAN terminal 103 receives the received signal level of the wireless LAN base station 101 belonging to the received signal level management unit 1032, the handover processing unit 1033 The scan processing time T1 is calculated based on the received signal level from the station 101, and the scan processing time T1 is output to the internal counter 1035. The subsequent processing is the same.

  The scan process switching unit 1034 receives the notification of the start of the scan process, outputs a switching command to the radio unit transceiver unit 1031 to scan information from the beacon signal from the surrounding wireless LAN base station, and starts the scan process. (Step S3).

  Between step S3 at the start of the scanning process and step S5 at the end of the scanning process, the frame from the wired LAN terminal 104 via the wireless LAN base station 101 is not received and discarded.

  Next, after the scan processing in step S3 is started, the wireless LAN terminal 103 scans the reception signal levels of the wireless LAN base station 101 and the wireless LAN base station 102 from the beacon signal, and collects scan information by the reception signal level management unit 1032. The received signal level is monitored. As shown in FIG. 3, the received signal level of the assigned wireless LAN base station 101 is stored in the first element, and the received signal level of the wireless LAN base station 102 is stored second (step S4).

  An internal counter 1035 sends an elapse notification of the scan processing time T1 to the handover processing unit 1033, and the handover processing unit 1033 notifies the scan processing switching unit 1034 of the end of the scan processing. In response to the notification of the end of the scan process, the scan process switching unit 1034 instructs the wireless unit transmitting / receiving unit 1031 to end the scan process (step S5).

  The reception signal level management unit 1032 outputs to the handover processing unit 1033 the reception signal level of the wireless LAN base station 102 having the strongest reception signal level in the vicinity of the wireless LAN base station 101 to which it belongs. The handover processing unit 1033 compares and determines the received signal levels of the wireless LAN base station 101 and the wireless LAN base station 102. If the received signal level of the wireless LAN base station 101 is stronger, the wireless LAN terminal 103 returns to step S1 again while receiving the frame (step S6).

  If the received signal level of the wireless LAN base station 102 is stronger, an attribution cancellation request is transmitted from the wireless LAN terminal 103 to the wireless LAN base station 101, and attribution with the wireless LAN base station 101 is canceled (step S7).

  By transmitting the attribution request from the wireless LAN terminal 103 to the wireless LAN base station 102, the wireless LAN terminal 103 belongs to the wireless LAN base station 102 (step S8).

  As described above, the necessity of the handover process is determined on the wireless LAN terminal 103 side, and the data transmission / reception and the scanning process are switched.

  In addition, although the handover process in the case where there are two wireless LAN base stations constituting the wireless LAN system has been described, the number of wireless LAN base stations is not limited. When it is configured with three or more wireless LAN base stations, the following operation is performed.

  When the received signal level management unit 1032 of the wireless LAN terminal 103 stores information on the received signal level from the neighboring wireless LAN base stations, the received signal level is stored in order of the second and subsequent strongest received signal levels. Other processing is the same as the handover method already described, and is omitted here.

  Furthermore, although the case where there is one wireless LAN terminal belonging to the wireless LAN base station has been described, the number of wireless LAN terminals belonging to each wireless LAN base station is not limited. Even when a plurality of wireless LAN terminals belong to one wireless LAN base station, the MAC address of the wireless LAN terminal belonging to each wireless LAN terminal by the belonging terminal management table of the wireless LAN base station Since the handover process request information is centrally managed, the above-described handover method is applicable.

  FIG. 5 is a diagram showing the relationship between the scan processing time T1 and the received signal level.

  Referring to FIG. 5, when the scan processing time T1 is given, the scan processing time T1 is set longer as the received signal level is much lower than the quality sufficient for communication. This is a critical situation where communication is not possible when the received signal level is weak, so it is necessary to reliably capture a wireless LAN base station with a strong received signal level. Because. Conversely, when the received signal level is strong, the communication is stable and the scan processing time is set short.

  As described above, according to the present invention, in a wireless LAN system including a plurality of wireless LAN base stations and wireless LAN terminals, the wireless LAN base station to which the wireless LAN terminal belongs is replaced with another wireless LAN base as the wireless LAN terminal moves. When performing handover to a station, data transmission / reception and scan processing are switched to obtain information on received signal levels from neighboring base stations, search for a wireless LAN base station with the highest received signal level, and perform handover. To do.

  During the handover process, only one receiver is required on the wireless LAN terminal side, and since the handover is actively performed before the membership is lost, the time required for the handover can be shortened compared to the conventional method. .

  As described in FIG. 1, the features of the present invention are summarized in the following operations.

  The reception signal level management unit 1032 monitors the reception signal level from the wireless LAN base station 101 to which the wireless LAN terminal 103 belongs, and sends the reception signal level information from the reception signal level management unit 1032 to the handover processing unit 1033. The handover processing unit 1033 determines whether or not a sufficient received signal level is obtained.

  When a sufficient received signal level is not obtained, the scan process switching unit 1034 is notified of the start of the scan process. It switches so that the beacon signal from a surrounding wireless LAN base station may be scanned, and the reception signal level from each wireless LAN base station is collected.

  During the scanning process, the frame from the wireless LAN base station cannot be received and discarded.

  When the beacon signals from the wireless LAN base station 101 and the wireless LAN base station 102 are obtained, the received signal level from each wireless LAN base station is collected by the received signal level management unit 1032. The handover processing unit 1033 compares the received signal level of the wireless LAN base station 101 with the received signal level of the wireless LAN base station 102, and when the received signal level of the wireless LAN base station 102 is stronger than the wireless LAN base station 101, The wireless LAN terminal 103 transmits an attribution request to the wireless LAN base station 102 at the same time as making an attribution cancellation request to the wireless LAN base station 101, and switches the attribution to the wireless LAN base station 102.

  Conventionally, since a wireless LAN terminal has been searching for a signal from a neighboring wireless LAN base station after it cannot receive a signal from the wireless LAN base station, it took time to cancel the attribution and perform new attribution in handover. The present invention actively starts the handover process when the received signal level becomes weak, while performing the data transmission / reception process and the scan process of the received signal level of the surrounding wireless LAN base station in parallel in a time-sharing manner, The wireless LAN terminal itself determines the handover timing to another wireless LAN base station and executes the handover. In this way, the handover is performed not by the reception signal level disappearing but by performing a handover to another base station having a stronger reception signal level while maintaining the attribution with the base station of the handover source. Processing time can be shortened and seamless handover can be realized.

  There are mainly two effects in the present invention. The first effect is that the time required for the handover process by the wireless LAN terminal can be greatly reduced as compared with the conventional case. The reason is that the wireless LAN terminal constantly monitors the received signal level while maintaining the belonging to the wireless LAN base station, and restricts data transmission / reception when it is determined that the received signal level is not of sufficient quality. This is because by taking time to scan the level of the received signal from the wireless LAN base station, a nearby wireless LAN base station with a stronger signal is found and handed over to that side. This greatly reduces the interruption time of data transmission / reception between attribution cancellation and peripheral wireless LAN base station search compared to the conventional method of starting searching for neighboring wireless LAN base stations after the attribution is completely cancelled. can do.

  As a result, the possibility of occurrence of a transmission / reception timeout in End-to-End data transmission / reception in progress in the upper layer is reduced. For example, in streaming applications that require continuity and real-time communication in higher layers and multimedia communication such as VoIP, the user can continue to use the application without being aware of communication interruption due to handover. Become.

  The second effect is that since the data transmission / reception and the received signal level scanning process are performed in a time-sharing manner, the present invention can be implemented by a single receiver, and the implementation cost can be kept low. In addition to the mounting cost, there is an advantage that power saving and downsizing of the wireless LAN terminal can be promoted.

It is a block diagram which shows one Embodiment of the wireless LAN handover processing system of this invention. It is a block diagram which shows the detail of the wireless LAN terminal of FIG. It is a figure explaining the table of the MAC address which the received signal level management part of FIG. 2 has. 3 is a flowchart showing an operation procedure of the handover process of FIG. 1. It is a figure which shows the relationship between scanning process time T1 and a received signal level.

Explanation of symbols

101 wireless LAN base station 102 wireless LAN base station 103 wireless LAN terminal 104 wired terminal 105 wired LAN
1031 Radio unit transceiver unit 1032 Received signal level management unit 1033 Handover processing unit 1034 Scan processing switching unit 1035 Internal counter

Claims (10)

A plurality of wireless LAN base stations and at least one wireless LAN terminal that is located and moves under each of the plurality of wireless LAN base stations,
When the reception level of the wireless LAN terminal becomes weak , the scan time is set based on the reception signal level, and the data transmission / reception processing and the scanning processing of the reception signal level of the surrounding wireless LAN base station are time-shared. The wireless LAN handover processing method is characterized by switching to the wireless LAN base station having a strong received signal level while performing in parallel. A wireless LAN terminal located under one of a plurality of wireless LAN base stations,
When the received signal level becomes weak , the scan time is set based on the received signal level, and the data transmission / reception process and the scan process of the received signal level of the surrounding wireless LAN base station are performed in time division in parallel. The wireless LAN terminal is switched to the wireless LAN base station having a strong received signal level. A plurality of wireless LAN base stations and at least one wireless LAN terminal that is located and moves under each of the plurality of wireless LAN base stations,
The wireless LAN terminal includes a wireless part transceiver unit for performing communication in a wireless section, a reception signal level management part for managing a reception signal level of a peripheral wireless LAN base station input from the wireless part transceiver part, and the reception signal A handover processing unit that determines the necessity of the handover process based on the level, and a request to switch between the inter-station communication and the process of scanning the reception signal level of the surrounding wireless LAN base station according to an instruction of the handover processing unit. The scan processing switching unit that outputs to the radio unit transmitting / receiving unit and the scan processing time preset based on the received signal level by the handover processing unit are monitored, and the monitoring result is notified to the scan processing switching unit And a wireless LAN handover processing method. A wireless LAN terminal located under one of a plurality of wireless LAN base stations,
A wireless unit transceiver unit for performing communication in a wireless section, a received signal level management unit for managing received signal levels of peripheral wireless LAN base stations input from the wireless unit transceiver unit, and a hand based on the received signal level A handover processing unit for determining the necessity of over processing, and a request for switching between inter-station communication and processing for scanning received signal levels of neighboring wireless LAN base stations according to an instruction from the handover processing unit to the wireless unit transmission / reception unit A scan process switching unit for outputting, and an internal counter for monitoring a scan processable time set in advance based on a received signal level by the handover processing unit and notifying the scan process switching unit of a monitoring result A wireless LAN terminal characterized by that. The received signal level manager is
By receiving the beacon signal via the wireless unit transmitting / receiving unit, the received signal level from the wireless LAN base station to which it belongs and the wireless LAN base station existing in the vicinity, and the MAC (Media Access Control) of each wireless LAN base station The addresses are centrally managed, and the received signal levels and the MAC addresses from the first and second wireless LAN base stations are stored in a table from the received beacon signal, and always belong to the first 4. The wireless LAN base station is stored first, and the information on the second wireless LAN base station in the vicinity is sorted in descending order of reception signal level and stored in the second and later. Wireless LAN handover processing method. The handover processor is
It is determined whether or not the level of the received signal from the first wireless LAN base station to which it belongs is maintained at a sufficient quality, notifies the scan process start and the scan process end to the scan process switching unit, and Switch the wireless LAN base station by comparing and judging the strongest wireless LAN base station among the received signal levels of the LAN base station and the received signal level from the first wireless LAN base station to which the wireless LAN terminal belongs. 6. The wireless LAN handover processing method according to claim 3, wherein processing is performed. The scan processing switching unit
Upon receiving notification of the start of scanning processing from the handover processing unit, instructs the wireless unit transmitting / receiving unit to start scanning the beacon signal of the neighboring wireless LAN base station, and requests switching of the wireless LAN base station The wireless communication device according to claim 3, 5 or 6, wherein upon receiving notification of completion of scanning processing from the handover processing unit, the wireless unit transmission / reception unit is requested to switch to terminate scanning. LAN handover processing method. The internal counter is
8. The wireless LAN handover processing method according to claim 3, wherein the scanning processing time preset in the handover processing unit is monitored. A plurality of wireless LAN base stations and at least one wireless LAN terminal that is located and moves under each of the plurality of wireless LAN base stations, the wireless LAN terminal is a wireless unit for performing communication in a wireless section A transmission / reception unit, a reception signal level management unit that manages reception signal levels of peripheral wireless LAN base stations, a handover processing unit that determines necessity of handover processing based on the reception signal level, inter-station communication, A wireless LAN handover processing method for a wireless LAN system having a scan processing switching unit that switches processing for scanning a received signal level of a peripheral wireless LAN base station, and an internal counter that monitors a scan processable time,
A first monitoring step in which the wireless LAN terminal monitors the received signal level of the first wireless LAN base station to which the wireless LAN terminal belongs by the received signal level management unit;
The received signal level management unit scans the received signal level of the first wireless LAN base station to which the received signal level belongs, and outputs a scan result to the handover processing unit. A first comparison and determination step of determining whether or not the received signal level of the base station is a value sufficient to perform communication by comparing with a preset value;
When the reception signal level of the first wireless LAN base station is a reception signal level sufficient for communication, the process returns to the first monitoring step, and when the reception signal level is not sufficient for communication, The handover processing unit notifies the scan processing switching unit of the start of scan processing, notifies the internal counter of the scan processing time based on the received signal level, and notifies the radio unit transceiver unit of the peripheral A scan process start step for outputting a switching command to scan information from a beacon signal from a wireless LAN base station and starting a scan process;
After starting the scanning process, the reception signal levels of the first wireless LAN base station and the second wireless LAN base station are scanned from the beacon signal, and the reception signal level management unit collects the scan information and belongs to it. A second signal level monitoring step of monitoring a received signal level of the first wireless LAN base station and a received signal level of the second wireless LAN base station;
When the received signal level of the second wireless LAN base station is stronger than the received signal level of the first wireless LAN base station, the handover processing unit notifies the scan processing switching unit of the end of scanning processing, and the wireless A scan process end step for instructing the unit transceiver unit to end the scan process;
After completion of the scan in the scan processing end step, the second comparison returns to the first signal level monitoring step again when the received signal level is compared and judged and the received signal level of the first wireless LAN base station is sufficient A decision step;
If the received signal level of the second wireless LAN base station is stronger than the received level of the first wireless LAN base station in the second comparison and determination step, the wireless LAN terminal sends the first wireless LAN. An attribution cancellation step of transmitting an attribution cancellation request to the base station and canceling the attribution with the first wireless LAN base station;
An attribution step belonging to the second wireless LAN base station by transmitting an attribution request from the wireless LAN terminal to the second wireless LAN base station;
A wireless LAN handover processing method comprising: A determination step of determining whether a sufficient received signal level is obtained from the wireless LAN base station in communication;
A scan process start step for setting a scan time based on the received signal level and starting a scan process for the neighboring wireless LAN base stations when it is determined that the sufficient received signal level is not obtained;
A received signal comparing step of comparing received signal levels from the neighboring wireless LAN base stations during the scanning process;
An attribution request step of transmitting an attribution request to a wireless LAN base station determined to have obtained a stronger received signal level in the received signal comparison step among the neighboring wireless LAN base stations;
A method of wireless LAN handover processing, comprising:

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