JP5077708B2 - Terminal apparatus, handover method thereof, and communication system - Google Patents

Description

  The present invention relates to a terminal device, a handover method thereof, and a communication system, and more particularly to a handover method of a wireless local area network (LAN) terminal device and a communication system including the terminal device.

  Between a wireless base station (hereinafter referred to as “access point”) and a wireless LAN (hereinafter referred to as “WLAN” (Wireless LAN)) terminal device, a real-time transfer protocol (hereinafter referred to as “RTP” (Real- The call is made using “time Transport Protocol”. The WLAN terminal device obtains the received electric field strength (hereinafter referred to as “RSSI” (Receive Signal Strength Indicator)) when the RTP is received. The WLAN terminal device acquires the RSSI value a specific number of times, and determines whether or not to execute handover based on the average value (see, for example, Patent Document 1).

  FIG. 8 is a schematic diagram showing an example of the timing of the handover determination time in the WLAN terminal apparatus related to the present invention. In the figure, for convenience, the RSSI acquisition (sampling) count is 10 times, and at this time, how much difference occurs in the handover execution determination time when the payload size is 20 ms and 40 ms, for example. Is shown.

  Since only one information is stored in one packet of each RTP (1) to (10), the RSSI value inevitably increases the execution determination time of the handover when the payload size is large. That is, assuming that the handover execution determination time when the payload size is 20 ms is T1 (sec) and the handover execution determination time when the payload size is 40 ms is T2 (sec), T1 <T2. As described above, the handover execution determination time varies depending on the payload size.

  On the other hand, as an example of handover control, a wireless LAN is disclosed in which a scan time is calculated based on a payload size, scan is performed to obtain reception level information, and a wireless LAN access point is switched based on the reception level information. (See Patent Document 2).

  As another example, quality offset values that take measurement accuracy into account are acquired, and for mobile devices that can measure the communication system with high accuracy and mobile devices that can be measured for a short time, the quality offset value is lowered and communication is performed with low accuracy. For mobile equipment that can measure the system and mobile equipment that can be measured for a long time, the quality offset value is increased, RSSI (or CRC result) is used as the quality type, and the number of times of communication quality measurement is determined according to the quality offset and handover is performed. A mobile device that performs the above is disclosed (see Patent Document 3).

JP 2008-141227 A JP 2007-067610 A JP 2006-310773 A

  However, in the invention described in Patent Document 1, when the payload size is relatively large, it takes a long time to determine whether or not to execute handover, and there is a problem that sound quality deterioration occurs near the occurrence of handover when moving at high speed. It was. The reason is that the acquisition time of the received electric field strength required for the handover switching determination becomes longer.

  The invention described in Patent Document 2 calculates the scan time based on the payload size, but the configuration unique to the present invention of “determining the number of times of reception field strength value acquisition based on the payload size” is patented. It is not described in Document 2. Therefore, the above-described problem cannot be solved by the invention described in Patent Document 2.

  Moreover, although the invention described in Patent Document 3 is common to the present invention in that the number of times of measurement of communication quality is determined, the number of times of measurement of communication quality is not determined according to the payload size, but according to the quality offset. The number of times of communication quality measurement is determined. Therefore, since the invention described in Patent Document 3 is completely different from the present invention, the above problem cannot be solved.

  Therefore, an object of the present invention is to determine whether or not to execute handover in a relatively short time even when the payload size is relatively large, and therefore, sound quality degradation occurs in the vicinity of handover occurrence when moving at high speed. It is an object of the present invention to provide a terminal device, a handover method thereof, and a communication system capable of preventing the occurrence of the failure.

  In order to solve the above problems, a terminal device according to the present invention receives a payload size acquisition unit that acquires a payload size determined with a base station, and receives and receives a voice data packet transmitted from the base station. Based on the received field strength value acquisition unit that acquires the field strength value and the payload size acquired by the payload size acquisition unit, the number of times the received field strength value is acquired by the reception field strength value acquisition unit is determined, and the number of times determined And a handover determination unit that determines whether or not handover is executed based on the received field strength value of the corresponding minutes.

  The handover method according to the present invention also includes a payload size acquisition step for acquiring a payload size determined with the base station, and receives a voice data packet transmitted from the base station and acquires a received field strength value thereof. Based on the received field strength value acquisition step and the payload size acquired in the payload size acquisition step, the number of times of reception field strength value acquisition in the reception field strength value acquisition step is determined, and the received field strength value for the determined number of times And a handover determination step of determining whether or not to execute handover based on the terminal device.

  In addition, the communication system according to the present invention receives a payload size acquisition unit that acquires a payload size determined with a base station, and receives a voice data packet transmitted from the base station and acquires a received electric field strength value thereof. Based on the payload size acquired by the reception field strength value acquisition unit and the payload size acquisition unit, the number of reception field strength value acquisition times in the reception field strength value acquisition unit is determined, and the reception field strength value for the determined number of times And a handover determination unit for determining whether or not to execute handover based on the above.

  The program according to the present invention also includes a payload size acquisition step for acquiring a payload size determined with the base station, and a reception for receiving a voice data packet transmitted from the base station and acquiring a reception field strength value thereof. Based on the payload size acquired in the field strength value acquisition step and the payload size acquisition step, the number of times of reception field strength value acquisition in the reception field strength value acquisition step is determined, and the received field strength value for the determined number of times is determined. And a handover determination step of determining whether or not to execute handover based on the computer of the terminal device.

  According to the present invention, even when the payload size is relatively large, it is possible to determine whether or not handover is executed in a relatively short time, and therefore, when moving at high speed, sound quality degradation occurs near the occurrence of handover. It becomes possible to prevent.

It is a block diagram of an example of the terminal device for demonstrating the principle of operation of the terminal device which concerns on this invention. It is a block diagram of 1st Embodiment of the terminal device which concerns on this invention. FIG. 3 is a schematic explanatory diagram illustrating an operation of the first embodiment. It is a flowchart which shows operation | movement of 1st Embodiment. It is a block diagram of 2nd Embodiment of the terminal device which concerns on this invention. It is a flowchart which shows operation | movement of 2nd Embodiment. It is a block diagram of an example of the communication system which concerns on this invention. It is a schematic diagram which shows an example of the timing of the determination time of the hand-over in the WLAN terminal device relevant to this invention.

  First, the operation principle of the present invention will be described before the description of the embodiment. FIG. 1 is a configuration diagram of an example of a terminal device for explaining the operation principle of the terminal device according to the present invention. Referring to the figure, a terminal device 100 according to the present invention includes a payload size acquisition unit 1, a received electric field strength value acquisition unit 2, and a handover determination unit 3.

  The payload size acquisition unit 1 acquires a payload size determined with a base station (not shown). The reception field strength value acquisition unit 2 receives the voice data packet transmitted from the base station and acquires the reception field strength value. Based on the payload size acquired by the payload size acquisition unit 1, the handover determination unit 3 determines the number of reception field strength value acquisitions in the reception field strength value acquisition unit 2, and performs handover based on the determined number of reception field strength values. Whether or not to execute is determined.

  Thus, according to the present invention, since the reception field strength value acquisition unit 2 determines the number of times of reception field strength value acquisition based on the payload size, the reception field strength value is acquired according to the payload size. The time required can be changed. Therefore, even when the payload size is relatively large, it is possible to prevent deterioration of sound quality in the vicinity of handover occurrence when moving at high speed.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, the first embodiment will be described. FIG. 2 is a block diagram of the first embodiment of the terminal device according to the present invention. Referring to the figure, the terminal device 10 according to the present invention includes a payload size acquisition unit 31, an RSSI value acquisition unit 32, a handover determination unit 33, a control unit 34, and a program storage unit 35. The Note that the payload size acquisition unit 31, the RSSI value acquisition unit 32, and the handover determination unit 33 correspond to the payload size acquisition unit 1, the received electric field strength value acquisition unit 2, and the handover determination unit 3 of FIG.

  The terminal device 10 is a WLAN terminal as an example. However, the terminal device 10 is not limited to a WLAN terminal, and the present invention can be applied to any terminal device that communicates with at least a base station (or access point) (not shown).

  The payload size acquisition unit 31 acquires the payload size set by the terminal device 10. The RSSI value acquisition unit 32 extracts and acquires the RSSI value included in the RTP from the base station (hereinafter referred to as “access point”). The handover determination unit 33 determines whether or not to execute handover based on the information acquired by the payload size acquisition unit 31 and the RSSI value acquisition unit 32. The program storage unit 35 stores a handover method program to be described later. The control unit 34 controls the payload size acquisition unit 31, the RSSI value acquisition unit 32, and the handover determination unit 33 based on the program stored in the program storage unit 35.

  Next, the operation of the first embodiment will be described. FIG. 3 is a schematic explanatory view showing the operation of the first embodiment, and FIG. 4 is a flowchart showing the operation of the first embodiment. The following operation is executed by the control unit 34 controlling the payload size acquisition unit 31, the RSSI value acquisition unit 32, and the handover determination unit 33.

  First, the payload size acquisition unit 31 acquires the payload size determined by the negotiation between the WLAN terminal 1 and the access point, and stores it in a memory (not shown) (step S1).

  Next, the RSSI value acquisition unit 32 acquires the RSSI value when the RTP transmitted from the access point during voice communication is received, and stores it in a memory (not shown) (step S2).

  Next, the handover determination unit 33 determines the RSSI acquisition count (sampling count) based on the value of the payload size acquired by the payload size acquisition unit 31 and acquires the RSSI value from the RSSI value acquisition unit 32 by the number of times. (Step S3).

  Next, the handover determination unit 33 determines whether or not to execute handover based on the RSSI value acquired from the RSSI value acquisition unit 32 (step S4).

  Referring to FIG. 3, an example of the handover execution determination time in the first embodiment is shown. In the drawing, for the sake of convenience, the handover execution determination time when the payload size is 20 ms and 40 ms is shown. Referring to the figure, when the payload size is 20 ms, the handover determining unit 33 of the WLAN terminal 1 determines the number of times of sampling as 10 times. At this time, the handover execution determination time is assumed to be T3 (sec). Then, the handover determination unit 33 determines whether or not to execute the handover based on the RSSI value included in the RTP (1) to RTP (10).

  On the other hand, when the payload size is 40 ms, the handover determining unit 33 of the WLAN terminal 1 determines the number of samplings as 5 times. At this time, the handover execution determination time is assumed to be T4 (sec). Then, the handover determining unit 33 determines whether or not to execute the handover based on the RSSI value included in RTP (1) to RTP (5).

  In this case, the handover execution determination time is substantially equal for both T3 and T4. That is, when the payload size is 40 ms, when normal sampling is performed 10 times, the number of times is decreased to 5 times, so that the handover execution determination time is shortened to T4.

  As described above, according to the first embodiment of the present invention, by making the RSSI sampling frequency variable based on the payload size, it is possible to shorten the handover determination time even when the payload size is relatively large. it can. As a result, it is possible to reduce deterioration in sound quality near the occurrence of handover in the WLAN terminal 1 that is talking at high speed.

  Next, a second embodiment will be described. In the second embodiment, a moving speed detection unit is added to the configuration of the first embodiment. FIG. 5 is a configuration diagram of a second embodiment of a terminal apparatus according to the present invention. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  When the moving speed of the terminal device is relatively low, deterioration in sound quality near the occurrence of handover is not a problem. Therefore, when the moving speed of the terminal device is relatively low, a function that does not reduce the number of times of RSSI value sampling is added in the second embodiment.

  Referring to FIG. 5, the terminal device 1 according to the present invention is obtained by adding a moving speed detector 36 to the configuration of the first embodiment (see FIG. 2). Other configurations are the same as those of the first embodiment. The movement speed detection unit 36 detects the movement speed of the terminal device 1 itself. The handover determining unit 33 determines whether or not it is necessary to determine the RSSI sampling frequency based on the moving speed information of the terminal device 1 obtained from the moving speed detecting unit 36.

  The operation of the second embodiment will be described below. FIG. 6 is a flowchart showing the operation of the second embodiment. The following operation is executed by the control unit 34 controlling the payload size acquisition unit 31, the RSSI value acquisition unit 32, the handover determination unit 33, and the movement speed detection unit 36.

  First, the payload size acquisition unit 31 acquires the payload size determined by the negotiation between the WLAN terminal 1 and the access point, and stores it in a memory (not shown) (step S11).

  Next, the RSSI value acquisition unit 32 acquires the RSSI value when receiving the RTP sent from the access point during voice communication, and stores it in a memory (not shown) (step S12).

  Next, the moving speed detector 36 detects the moving speed of the terminal device 1 (step S13).

  Next, the handover determining unit 33 determines whether or not the moving speed of the terminal device 1 detected by the moving speed detecting unit 36 is equal to or higher than a predetermined threshold (step S14).

  As a result, when the moving speed of the terminal device 1 is equal to or higher than the predetermined threshold (in the case of “Y” in step S14), the handover determining unit 33 is based on the payload size value acquired by the payload size acquiring unit 31. The RSSI acquisition frequency (sampling frequency) is determined, and the RSSI value is acquired from the RSSI value acquisition unit 32 by that number of times (step S16).

  Next, the handover determining unit 33 determines whether or not to execute handover based on the acquired RSSI value (step S17).

  On the other hand, when the moving speed of the terminal device 1 is less than the predetermined threshold value in step S14 (in the case of “N” in step S14), the handover determination unit 33 does not decrease the sampling count below the current count. The RSSI value is acquired from the RSSI value acquisition unit 32 (step S15).

  Next, the handover determining unit 33 determines whether or not to execute handover based on the acquired RSSI value (step S17).

  As described above, according to the second embodiment of the present invention, even when the payload size is relatively large, the handover determining unit 33 obtains the moving speed information of the terminal device 1 from the moving speed detecting unit 36. When the moving speed of the terminal device 1 is relatively slow, the handover determination can be performed without reducing the number of samplings, thereby reducing the deterioration of the sound quality of the handover.

  Next, a third embodiment will be described. The third embodiment relates to a communication system. FIG. 7 is a block diagram of an example of a communication system according to the present invention. In the figure, the same components as those in FIGS. 1, 2, and 5 are denoted by the same reference numerals, and the description thereof is omitted.

  Referring to FIG. 7, an example of a communication system according to the present invention includes a base station 101, a service area 103 of the base station 101, a base station 102, a service area 104 of the base station 102, and terminal apparatuses 10, 20 or 100. In addition, handover is performed at the boundary 105 between the service areas 103 and 104.

  In the figure, as an example, an operation of determining whether or not handover is executed at the boundary 105 when the terminal device 10, 20 or 100 moves from the service area 103 to the service area 104 is shown. Since the contents of the operation have been described in the first and second embodiments, description thereof is omitted here.

  In the third embodiment, an example in which there are two base stations and one terminal device has been described. However, the present invention is not limited to this, and there are three or more base stations and two terminal devices. The present invention can also be applied in the above case.

  As described above, according to the third embodiment of the present invention, even when the payload size is relatively large, it is possible to determine whether or not to execute the handover in a relatively short time, and thus it is possible to move at high speed. In this case, a communication system capable of preventing deterioration of sound quality near the occurrence of handover can be obtained.

  Next, a fourth embodiment will be described. The fourth embodiment relates to a handover method program. Referring to FIG. 2, the terminal device 1 according to the present invention includes a program storage unit 35. The program storage unit 35 stores a program for the handover method shown in the flowchart of FIG. The control unit 34 (computer) reads the program from the program storage unit 35 and controls the payload size acquisition unit 31, the RSSI value acquisition unit 32, and the handover determination unit 33 according to the program. Since the contents of the control have already been described, description thereof is omitted here.

  Similarly, referring to FIG. 5, the terminal device 1 according to the present invention includes a program storage unit 35. The program storage unit 35 stores a program for the handover method shown in the flowchart of FIG. The control unit 34 (computer) reads the program from the program storage unit 35 and controls the payload size acquisition unit 31, the RSSI value acquisition unit 32, the handover determination unit 33, and the movement speed detection unit 36 according to the program. Since the contents of the control have already been described, description thereof is omitted here.

  As described above, according to the fourth embodiment of the present invention, even when the payload size is relatively large, it is possible to determine whether or not to execute the handover in a relatively short time, and therefore, it is possible to move at high speed. In this case, it is possible to obtain a handover method program in a terminal device that can prevent deterioration in sound quality near the occurrence of handover.

1,31 Payload size acquisition unit
2 Received field strength value acquisition unit
3 Handover determination unit 10, 20 Terminal device
32 RSSI value acquisition unit
33 Handover determination unit
34 Control unit
35 Program storage
36 Moving speed detector
100 Terminal equipment 101, 102 Base station 103, 104 Service area
105 boundary

Claims (16)

A payload size acquisition unit for acquiring a payload size determined with a base station;
A reception field strength value acquisition unit that receives a voice data packet transmitted from the base station and acquires a reception field strength value thereof;
Based on the payload size acquired by the payload size acquisition unit, determine the number of times of reception field strength value acquisition in the reception field strength value acquisition unit, and determine whether or not to execute handover based on the received field strength value for the determined number of times And a handover determining unit.   When the handover determination unit has at least two types of payload sizes, ie, a first payload size and a second payload size, and the second payload size is larger than the first payload size, the first payload size The terminal device according to claim 1, wherein the number of acquisition times of the reception field strength value in the second payload size is less than the number of acquisition times of the reception field strength value in. Including a moving speed detector for detecting the moving speed of the device itself,
The terminal apparatus according to claim 1, wherein the handover determination unit determines whether or not it is necessary to determine the number of acquisition times of the received electric field strength value based on a movement speed detected by the movement speed detection unit.   The handover determining unit determines the number of times the received electric field strength value is acquired when the moving speed detected by the moving speed detecting unit is equal to or greater than a predetermined threshold, and the moving speed detected by the moving speed detecting unit is predetermined. The terminal device according to claim 3, wherein the number of acquisitions of the received electric field strength value is not decreased when the threshold value is less than the threshold value. A payload size acquisition step of acquiring a payload size determined with a base station;
A reception field strength value acquisition step of receiving a voice data packet transmitted from the base station and acquiring a reception field strength value thereof;
Based on the payload size acquired in the payload size acquisition step, determine the number of times of reception field strength value acquisition in the reception field strength value acquisition step, and determine whether to execute handover based on the received field strength value for the determined number of times And a handover determination step for performing the handover of the terminal device.   In the handover determination step, when there are at least two types of payload sizes to be acquired, ie, a first payload size and a second payload size, and the second payload size is larger than the first payload size, the first payload size 6. The handover method according to claim 5, wherein the number of acquisition times of the reception field strength value in the second payload size is less than the number of acquisition times of the reception field strength value in. A moving speed detecting step for detecting a moving speed of the own device;
The handover method according to claim 5 or 6, wherein the handover determining step determines whether or not it is necessary to determine the number of acquisition times of the received electric field strength value based on the moving speed detected in the moving speed detecting step.   The handover determining step determines the number of times the received electric field strength value is acquired when the moving speed detected in the moving speed detecting step is equal to or greater than a predetermined threshold, and the moving speed detected in the moving speed detecting step is predetermined. 8. The handover method according to claim 7, wherein when the received electric field intensity value is less than a threshold value, the number of acquisition times of the received electric field strength value is not decreased. A payload size acquisition unit that acquires a payload size determined between the base station, a reception field strength value acquisition unit that receives a voice data packet transmitted from the base station and acquires a reception field strength value thereof, and Based on the payload size acquired by the payload size acquisition unit, the number of times of reception field strength value acquisition in the reception field strength value acquisition unit is determined, and whether or not handover is performed is determined based on the received field strength value for the determined number of times. A terminal device including a handover determination unit;
A communication system including the base station.   When the handover determination unit has at least two types of payload sizes, ie, a first payload size and a second payload size, and the second payload size is larger than the first payload size, the first payload size The communication system according to claim 9, wherein the number of acquisition times of the reception field strength value in the second payload size is less than the number of acquisition times of the reception field strength value in. The terminal device includes a moving speed detector that detects the moving speed of the own device,
11. The communication system according to claim 9, wherein the handover determination unit determines whether or not it is necessary to determine the number of acquisition times of the received electric field strength value based on a movement speed detected by the movement speed detection unit.   The handover determining unit determines the number of times the received electric field strength value is acquired when the moving speed detected by the moving speed detecting unit is equal to or greater than a predetermined threshold, and the moving speed detected by the moving speed detecting unit is predetermined. 12. The communication system according to claim 11, wherein when the received electric field intensity value is less than a threshold value, the number of acquisition times of the received electric field strength value is not decreased. A payload size acquisition step of acquiring a payload size determined with a base station;
A reception field strength value acquisition step of receiving a voice data packet transmitted from the base station and acquiring a reception field strength value thereof;
Based on the payload size acquired in the payload size acquisition step, determine the number of times of reception field strength value acquisition in the reception field strength value acquisition step, and determine whether to execute handover based on the received field strength value for the determined number of times A program for causing a computer of a terminal device to execute a handover determination step.   In the handover determination step, when there are at least two types of payload sizes to be acquired, ie, a first payload size and a second payload size, and the second payload size is larger than the first payload size, the first payload size 14. The program according to claim 13, wherein the number of acquisition times of the reception field strength value in the second payload size is less than the number of acquisition times of the reception field strength value in. A moving speed detecting step for detecting a moving speed of the own device;
The program according to claim 13 or 14, wherein the handover determining step determines whether or not it is necessary to determine the number of acquisition times of the received electric field strength value based on the moving speed detected in the moving speed detecting step.   The handover determining step determines the number of times the received electric field strength value is acquired when the moving speed detected in the moving speed detecting step is equal to or greater than a predetermined threshold, and the moving speed detected in the moving speed detecting step is predetermined. 16. The program according to claim 15, wherein the number of acquisitions of the received electric field strength value is not decreased when the threshold value is less than the threshold value.

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