JP2010087952A - Wireless communication apparatus and wireless communication program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless LAN communication apparatus that eliminates the need for an access point having special functions, and reduces useless roaming in an area in which electric waves from access points overlap, thereby achieving a more stable wireless LAN communication than before. <P>SOLUTION: The wireless LAN communication apparatus includes: a movement detection means for determining whether a wireless communication apparatus moves based on information from a predetermined means; and a roaming threshold setting means for setting a roaming threshold allowing easier roaming than in the case of the information indicating a still state, when the information from the movement detection means indicates movement of the wireless communication apparatus, and setting a roaming threshold causing harder roaming than in the case of the information indicating movement, when the information indicates a still state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication device and a wireless communication program, and more particularly to a roaming technique in a wireless communication device.

  Unlike a wired communication device, a wireless communication device typified by a wireless LAN device does not require a network cable to be connected for data communication. For this reason, when constructing a computer network, it is rapidly spreading due to its ease of construction, which requires less work than wired.

  One advantage of introducing a wireless LAN is that, for example, a computer with a built-in wireless LAN has a cleaner desk area. Furthermore, there is an advantage that a computer such as a notebook computer equipped with a battery can move freely and can communicate during the movement. Because of these advantages, there are an increasing number of cases where wireless LANs are introduced in large-scale facilities such as hospitals.

  One example of using a wireless LAN in a hospital is to attach a wireless transmitter to a patient and manage the patient's condition (for example, an electrocardiogram) wirelessly. This is a very effective use in hospitals where beds are frequently moved. In this case, it is also effective in reducing stress on the patient because it does not hinder the patient's free behavior.

  Another example of use in hospitals is to access patient examination data stored on a server through a notebook computer or PDA (Personal Digital Assistant) with a built-in wireless LAN function while a doctor is consulting or visiting a doctor. . With such a system, doctors can get the information they need when they need it, where they need it. In particular, being able to easily check a large amount of test data is thought to reduce the burden on doctors and help in accurate diagnosis.

  By the way, regarding the construction of a wireless LAN, normally, in a large-scale space, a plurality of access points are installed, and the area covered by each access point is partially overlapped to secure a wide service area. . On the other hand, when the wireless LAN communication apparatus can receive radio waves from a plurality of access points such as the overlapping communication areas as described above, the access point to be connected is determined by comparing the radio field strengths of the respective radio LAN communication apparatuses. Switch the connection to the corresponding access point and perform roaming. By performing such control, the wireless LAN communication device can communicate across different access points even during movement. However, this has the following problems.

  In areas where radio waves from access points overlap, for example, in areas where the distances from multiple access points are the same, the strength of the radio waves received by the wireless LAN communication device is almost the same, which is overwhelmingly strong. There is often no single radio wave that is dominant. In that case, there may be fluctuations in the received radio wave intensity, and when viewed from the wireless LAN communication device, the source having a superior radio wave intensity changes rapidly in a short time. In such a situation, if a method of determining an access point to be connected based on the radio field intensity is used, it is necessary to frequently switch the access point to be connected in synchronization with fluctuations in the received radio field intensity.

  This will be described in detail below. FIG. 1 shows a radio wave received by a wireless LAN communication apparatus when the wireless LAN communication apparatus moves from one of the two access points in the vicinity of one access point A toward the other access point B. It shows the change over time of the strength of the. In FIG. 1, the vertical axis represents radio wave intensity, and the horizontal axis represents time. Further, A indicates the time-dependent change in radio field intensity received from access point A and B the access point B, respectively. As is apparent from the figure, as time elapses, that is, as the wireless LAN communication device moves away from the access point A, the radio wave intensity from the access point A becomes weaker, and conversely, the radio wave intensity from the access point B that is approaching increases. It is getting stronger. This is because, generally, the intensity of the received radio wave has a relationship that decreases as the distance to the transmission source increases unless there are special circumstances. In FIG. 1, the range surrounded by the dotted line indicates the received radio wave intensity when the wireless LAN communication device is located at a position that is approximately the same distance from the access point A and the access point B.

  Next, in FIG. 2, the details of the received radio wave intensity in the area where the radio wave intensity from the access point A and the access point B overlap, that is, the range surrounded by the dotted line in FIG.

  FIG. 2 is an enlarged view of a range surrounded by a dotted line in FIG. As is apparent from the figure, the strengths of radio waves received by the wireless LAN communication apparatus from the access point A and the access point B are antagonized, and dominant radio waves are frequently switched. Next, the roaming operation of the wireless LAN communication device in such a state will be described.

  Referring to FIG. 2, the wireless LAN communication device initially communicates with access point A. Thereafter, with the movement of the wireless LAN communication device, the radio wave strength of the access point A that is in communication is weakened. When this falls below the roaming threshold, the wireless LAN communication device starts roaming, and the radio wave strength is strong at that time. Switch the connection to the other Ax point. Therefore, in FIG. 2, the connected access points are switched at the timings indicated by t1, t2, t3, t4, and t5. After t5, since the radio wave intensity from the access point B becomes completely dominant, the connection to the access point B is stably maintained.

  As is apparent from the above, when roaming from the access point A to the access point B, the wireless LAN communication device repeats roaming many times in a relatively short time period from t1 to t5. That is, in a situation where only one roaming is required ideally, the roaming is performed five times.

  Such frequent roaming in a short time not only greatly deteriorates the performance of wireless LAN communication, but also may cause a communication failure. In particular, medical devices such as those described above have been an important issue because a very high level of communication stability is required.

The following technologies are disclosed for the above unstable wireless communication.
JP-A-2004-007504

  Non-Patent Document 1 discloses that an arbitrary access point dynamically determines a roaming threshold for a wireless LAN communication device to switch access points based on the radio wave intensity from a neighboring access point, and this is determined as a wireless LAN communication device. The method of notifying is disclosed. However, this method can reduce useless roaming, but both the access point and the wireless LAN communication device require a function for this control, and is not practical in terms of cost.

  Therefore, the object of the present invention is to eliminate the need for roaming and enable more stable wireless LAN communication in an area where radio waves from access points overlap without requiring an access point equipped with a special function. A wireless LAN communication device is provided.

  A wireless communication device according to a first aspect of the present invention includes a movement detection unit that determines whether or not the wireless communication device is moving based on information from a predetermined unit, and information from the movement detection unit is stored in the wireless communication device. If it is information indicating movement, a roaming threshold is set so that roaming is easier than if it is information indicating stillness. If it is information indicating stillness, it is more than information indicating movement. Roaming threshold setting means for setting a roaming threshold so as to make roaming difficult.

  More preferably, the predetermined means is an acceleration sensor.

  More preferably, the movement detection means acquires a plurality of speed vectors of the wireless communication device within a predetermined time as information from the predetermined means, and the magnitude of the combined vector of the plurality of acquired speed vectors within the predetermined time is a predetermined value. If it is larger, it is determined to be moving, otherwise it is determined to be stationary.

  More preferably, the predetermined means records a plurality of radio wave intensities from the access point received by the wireless communication device itself for each access point within a predetermined time, and a dispersion value of the recorded radio wave intensity for a predetermined number of times. Is provided to the movement detection means, and the movement detection means determines that the movement is performed when at least one of the variance values is greater than a predetermined value, and otherwise determines that the movement is stationary.

  A wireless communication apparatus according to a second aspect of the present invention includes a moving speed detecting means for detecting a moving speed of a wireless communication apparatus based on information from a predetermined means, and a connected access point for the purpose of roaming timing control. Weighting means for weighting a weighting factor associated in advance with the moving speed of the wireless communication apparatus detected by the moving speed detecting means for each intensity of the radio wave from the access point not connected.

  More preferably, the wireless communication device further determines whether the wireless communication device is moving or stationary based on the moving speed of the wireless communication device detected by the moving speed detecting means, and the wireless communication device is moved. If it is determined that the camera is moving, the roaming threshold is set so that it is easier to roam than if it is determined to be stationary. If it is determined that it is stationary, roaming is performed more than if it is determined to be moving. Roaming threshold setting means for setting a roaming threshold to make it difficult to perform is provided.

  According to a third aspect of the present invention, there is provided a program for detecting whether or not a wireless communication device is moving based on information from a predetermined means on a computer provided in the wireless communication device. If the information from the mobile station indicates the movement of the wireless communication device, a roaming threshold is set so that the roaming is easier than the information indicating the stationary state. It is made to function as a roaming threshold value setting means for setting a roaming threshold value so as to make roaming more difficult than in the case of the information shown.

  More preferably, the predetermined means is an acceleration sensor.

  According to a fourth aspect of the present invention, there is provided a program comprising: a computer provided in a wireless communication apparatus, a moving speed detecting means for detecting a moving speed of the wireless communication apparatus based on information from a predetermined means; and roaming timing control. The purpose is to weight the weighting factor pre-associated with the moving speed of the wireless communication device detected by the moving speed detecting means for the intensity of the radio wave from the connected access point and the radio wave from the non-connected access point. Function as a weighting means.

  More preferably, the program further determines whether the wireless communication device is moving or stationary based on the moving speed of the wireless communication device detected by the moving speed detecting means. When a wireless communication device is determined to be moving, a roaming threshold is set to make roaming easier than when it is determined to be stationary, and when it is determined that the wireless communication device is stationary, it is moving It is made to function as a roaming threshold setting means for setting a roaming threshold so as to make roaming more difficult than when it is determined.

  According to the present invention, the wireless LAN communication device controls the roaming timing in accordance with its own movement (moving / stopping or moving speed), so that it is useless in an area where radio waves from access points overlap. Roaming can be reduced, and more stable communication is possible. Furthermore, since it is not necessary to mount a special function for implementing the present invention in the access point, it can be easily applied to an existing wireless LAN environment.

Embodiments according to the present invention will be described below with reference to the drawings. In addition, the same number is attached | subjected to the element which is common in each drawing, and description is not repeated.
<Example 1>
[Hardware configuration]

FIG. 3 is a hardware and software functional block diagram of the wireless LAN communication apparatus 301 according to the present invention. Referring to FIG. 3, the wireless LAN communication device 301 includes a CPU 303, a ROM 305, a RAM 307, an acceleration sensor 309, a wireless I / F 311, and a peripheral device I / F 313, which are connected by a bus. The acceleration sensor 309 detects the acceleration and speed of the wireless LAN communication device 301, the wireless I / F 311 communicates with other wireless devices such as an access point, and the peripheral device. The I / F 313 realizes connection between the wireless LAN communication device 301 and a host device such as a computer. Note that the CPU 303 implements each unit to be described later by executing a program.
[Software function]

  The movement detection unit 315 detects a signal from the acceleration sensor 309, determines whether the wireless LAN communication device 301 is moving, and transmits information indicating the result to the roaming threshold setting unit 317 described later. Specifically, it is determined from the signal received from the acceleration sensor 309 whether or not the acceleration of the wireless LAN communication device 301 is 0. If not, it is determined that the wireless LAN communication device 301 is moving.

  The roaming threshold setting unit 317 receives information from the movement detection unit 315 and sets the roaming threshold to a predetermined value. Specifically, the roaming threshold takes two values, which correspond to the case where the wireless LAN communication device 301 is in a moving state and the case where it is in a stationary state, respectively. In other words, the roaming threshold corresponding to the moving state is a value that is high and facilitates frequent roaming, while the roaming threshold corresponding to the stationary state is a value that is low and difficult to roam.

  The peripheral AP search means 319 determines whether the wireless LAN communication device 301 is receiving radio waves from an access point other than the connected access point. If it is received, it is further determined whether or not the wireless settings such as SSID and WEP of this access point are the same as that of the connected access point. Select as points. It is also possible to hold a plurality of wireless settings and roam candidates for access points having other wireless settings in addition to the connected access points.

  The roaming determination means 321 determines whether or not the radio wave intensity from the connected access point is below the roaming threshold, and if it is lower than the roaming candidate access points detected by the neighboring AP search means 319, It is determined whether or not there is an access point whose radio field intensity is stronger than that of the access point inside, and if it exists, the access point is determined as the access point to be roamed.

  In order to switch the connection to the access point determined by the roaming determination unit 321, the roaming unit 323 disconnects the connection with the currently connected access point and establishes a connection with a new access point.

The roaming threshold setting unit 317, the neighboring AP search unit 319, the roaming determination unit 321 and the roaming unit 323 are functions included in a so-called wireless driver 325.
[flowchart]

  FIG. 4 is a flowchart of the wireless LAN communication apparatus 301 according to the present invention.

  In S401, the roaming threshold setting unit 317 sets a value corresponding to the stationary state as the initial value of the roaming threshold.

  In S403, the neighboring AP search means 319 searches for an access point that is a roaming candidate, and if it exists, the process proceeds to S405, and if not, the process returns to S403.

  In step S405, the roaming determination unit 321 determines whether the radio wave intensity from the connected access point is lower than the roaming threshold, and whether there is an access point having a higher radio wave intensity than the connected access point. Thus, the access point to be roamed is determined. If the access point targeted for roaming is determined, the process proceeds to S407, and if not, the process proceeds to S409.

  In S407, the roaming means 323 roams to the access point determined in S405.

  In S409, the movement detecting unit 315 determines whether or not the wireless LAN communication device 301 is moving. If it is determined that the wireless LAN communication apparatus 301 is moving, the process proceeds to S411. Otherwise, the process proceeds to S413.

  In S411, the roaming threshold setting unit 317 sets the roaming threshold to a value corresponding to the movement state, and the process returns to S403.

In S413, the roaming threshold setting unit 317 sets the roaming threshold to a value corresponding to the stationary state if the value corresponds to the moving state, and the process returns to S403.
[Graph]

  FIG. 5 is a graph showing the relationship between the received radio wave intensity and the roaming threshold when the wireless LAN communication device 301 is moving and stationary. In this graph, as shown in FIG. 6, the wireless LAN communication apparatus 301 starts from the vicinity of one of the two access points (access point A) and moves toward the other access point (access point B). This is a case where the mobile station is moving and is once stationary at a position where the distance from both access points is equal.

  Referring to FIG. 5, since wireless LAN communication apparatus 301 is moving between 0 and t1, a roaming threshold corresponding to the moving state is adopted. The connected access point in this section is A. Since this graph is a graph when the wireless LAN communication apparatus 301 moves from the vicinity of the access point A toward the access point B, the radio wave intensity from the access point A decreases with the movement, and conversely, the access It can be seen that the radio wave intensity from point B is increasing.

  When the wireless LAN communication device 301 detects that it is in a stationary state at t1, it sets the roaming threshold to a threshold corresponding to the stationary state. Specifically, the roaming threshold is lowered to a predetermined value to make it difficult to roam.

  Between t1 and t2, the wireless LAN communication device 301 operates with a roaming threshold corresponding to the stationary state. In this section, since the radio field intensity of the access point A being connected does not fall below the roaming threshold, roaming does not occur and the connection to the access point A is maintained.

  When it is detected that the wireless LAN communication device 301 is in the moving state again at t2, the roaming threshold is set to a value corresponding to the moving state.

  At t3, since the radio wave intensity from the connected access point A is below the roaming threshold, the mobile phone roams to the access point B having a higher radio wave intensity at this point.

Thereafter, there is a section where B falls below the roaming threshold. In this section, the radio wave intensity from the access point B exceeds the radio wave intensity from the access point A, so that roaming does not occur and the connection to the access point B is established. Maintained.
[effect]

According to the present embodiment, since the wireless LAN communication device 301 changes the roaming threshold according to its own movement, even in a state where radio waves from a plurality of access points can be received, useless roaming does not occur, A stable communication state can be maintained. In addition, there is an effect that it is not necessary to make any changes to the access point in realizing this embodiment.
<Example 2>

  In the present embodiment, the movement determination method in the movement detector 315 of the first embodiment is changed. Specifically, a velocity vector for each unit time (for example, 100 msec) is recorded, and it is determined whether it is moving or stationary depending on whether the combined vector of the velocity vectors for a predetermined time exceeds a predetermined size. The velocity vector may be obtained by a well-known and conventional technique such as time integration of acceleration information obtained from the acceleration sensor 309. FIG. 7 shows the movement determination according to this embodiment.

  Referring to FIG. 7, a, b, c, d, and e are velocity vectors. Each is recorded every unit time such as 100 msec. Next, a combined vector of velocity vectors recorded every predetermined time, for example, every 500 msec, is calculated, and it is determined whether the moving state or the stationary state is based on whether the size of the combined vector is larger than the predetermined reference vector. In FIG. 7, (a) shows that the combined vector is less than the reference vector and is determined to be stationary, and (b) is larger than the reference vector and is determined to be moved. .

FIG. 8 shows a flowchart.
[flowchart]

  In step S801, the movement detection unit 315 sets a timer.

  In step S803, the movement detection unit 315 determines whether a signal indicating acceleration is received from the acceleration sensor. If received, the process proceeds to step S805. If not, the movement detection unit 315 determines that the signal is stationary (S815). finish.

  In step S805, the movement detection unit 315 records a unit time speed vector.

  In step S807, the movement detection unit 315 determines whether the timer set in step S801 has elapsed a predetermined time. If it has elapsed, the process proceeds to step S809; otherwise, the process returns to step S803.

  In step S809, the movement detection unit 315 calculates a combined vector by combining a plurality of recorded velocity vectors.

In S811, it is determined whether or not the combined vector calculated in S809 is larger than a predetermined reference vector, and if it is larger, it is determined that the moving state is present (S813), and this flow ends. On the other hand, otherwise, it is determined that it is in a stationary state (S815), and this flow ends.
[effect]

As described above, since the movement is determined using the combined vector of the velocity vectors for a predetermined time, it is possible to avoid erroneously determining that the movement is not a movement but a simple movement such as a simple shake. Furthermore, since the absolute moving distance from the starting point can be obtained using the combined vector in which the moving direction is taken into account, the movement can be determined based on this, so that a more strict determination can be made. As a result, frequent changes in the roaming threshold can be avoided and unnecessary roaming can be reduced.
<Example 3>

  This embodiment also changes the movement determination method in the movement detection means 315 of the first embodiment. Specifically, the radio field intensity of all access points capable of roaming is recorded periodically (for example, every 500 msec), and movement determination of the wireless LAN communication device 301 is performed based on this history. In the present embodiment, an invention in which the acceleration sensor used in the first embodiment is combined is disclosed, but the acceleration sensor is not necessarily required in the present embodiment.

  FIG. 9 is a radio wave intensity management table in which the radio wave intensity from the access point received by the wireless LAN communication apparatus 301 is recorded at a certain position. Referring to the figure, AP_A indicates access point A, and AP_B indicates access point B. In addition, each value has a maximum of 100, indicates the radio wave intensity from each access point, and the recording frequency is performed every 500 msec.

  Next, a predetermined number of recorded histories are integrated as one section, and a variance value in each section is calculated.

  FIG. 10 is a radio wave intensity dispersion table, which shows a variance value of a specific section in the recorded radio wave intensity history. Referring to the figure, the variance value of the radio field intensity received from access point A in the sections 1 to 4 is 35.69, and access point B is 25.25.

  Finally, when all of the dispersion values of the signal strength from each access point obtained above are below a predetermined threshold, it is determined that the wireless LAN communication device 301 is stationary, and even one exceeds the threshold. If it is, it is determined that it is moving.

  In the present embodiment, the number of roaming access points is two, but it is not necessary to be limited to this. Further, the timing for recording the radio wave intensity and the number of samples used for the variance value are not limited to the above example.

FIG. 11 shows a flowchart in the present embodiment.
[flowchart]

  In step S1101, the movement detection unit 315 creates a radio wave intensity management table corresponding to radio waves that can be roamed.

  In S1103, the movement detection unit 315 measures the radio wave intensity of the roamable radio wave and records each value in the radio wave intensity management table.

  In step S1105, the movement detection unit 315 determines whether the recorded radio wave intensity has reached a predetermined number. If the predetermined number has been reached, the process proceeds to S1107; otherwise, the process returns to S1103.

  In step S1107, the movement detection unit 315 calculates a variance value for a predetermined number of radio wave intensities for each radio wave.

  In step S1109, the movement detection unit 315 determines whether all of the calculated dispersion values are below a predetermined threshold value. If the calculated dispersion value is lower than the predetermined threshold value, the movement detection unit 315 proceeds to step S1115 and determines that it is in a stationary state. On the other hand, if even one exceeds the threshold, the process proceeds to S1111.

In step S1111, the movement detection unit 315 determines whether a signal indicating acceleration is received from the acceleration sensor. If the signal is received, the movement detection unit 315 proceeds to step S1113 to determine movement (S1113). On the other hand, if not, the process proceeds to S1115 and is determined to be stationary (S1115).
[effect]

As described above, it is possible to detect the movement of the wireless LAN communication apparatus without necessarily requiring an acceleration sensor by determining the movement using the dispersion value of the radio field intensity over a certain period of time, thereby enabling more accurate roaming. Become.
<Example 4>

  In this embodiment, the roaming timing is controlled by weighting the intensity of the received radio wave according to the moving speed of the wireless LAN communication apparatus 301.

  FIG. 12 shows the moving speed of the wireless LAN communication apparatus 301 and the weighting coefficient of the radio wave intensity at each moving speed. Referring to the table, AP_X indicates a connected access point, and AP_Y indicates a roaming access point. The table shows, for example, when the moving speed of the wireless LAN communication device 301 is 1 m / s to 5 m / s, the radio wave intensity from the connected access point AP_X is weighted by + 20%, and the roaming target access point It shows that -20% weighting is applied to the radio field intensity from AP_Y. The weighting coefficient is assigned a different value for each speed. Since weighting is performed separately for connected access points and other access points, even when three or more radio waves are received, other access points that are not connected are treated as one group. , The processing divided for each access point is not performed.

  FIG. 13 is a graph showing the intensity of received radio waves when the wireless LAN communication device 301 is moving at a speed of 10 m / s or higher. Referring to the figure, it can be seen that as the wireless LAN communication apparatus 301 moves, the radio wave intensity from the access point X decreases, and conversely, the radio wave intensity from the access point Y increases.

  When it is detected that the moving speed has reached 10 m / s at the timing of t1, the radio wave intensity from the access point X is weighted by -20% according to the table of FIG. + 20% weighting.

  Since the radio wave intensity from the access point X has fallen below the roaming threshold at the timing t2, the access point Y is roamed at this timing.

  t3 is the roaming timing when this embodiment is not used. As is apparent from the figure, by using this embodiment, the roaming timing is accelerated from t3 to t2. That is, when the moving speed is relatively fast, the received radio wave intensity is weighted so as to advance the roaming timing.

  Next, roaming when the moving speed is relatively slow will be described.

  FIG. 14 is a graph showing the intensity of the received radio wave when the wireless LAN communication device 301 is moving at a speed of 1 m / s to 5 m / s. Referring to the figure, it can be seen that as the wireless LAN communication apparatus 301 moves, the radio wave intensity from the access point X decreases, and conversely, the radio wave intensity from the access point Y increases.

  When it is detected that the moving speed has reached 1m / s to 5m / s at the timing of t1, + 20% of the radio wave intensity from the access point X is weighted according to the table of FIG. -20% weighting for signal strength.

  Since the radio wave intensity from the access point X has fallen below the roaming threshold at the timing t2, the access point Y is roamed at this timing.

  t3 is the roaming timing when this embodiment is not used. As is apparent from the figure, by using this embodiment, the roaming timing is delayed from t3 to t2. That is, when the moving speed is relatively slow, the received radio wave intensity is weighted so as to delay the roaming timing.

The weighting described above does not necessarily have to be performed for each received radio wave, and can be performed only for one of the radio waves from the connected access point. Therefore, the present invention can be easily applied even in a situation where radio waves from three or more access points are received. In addition to weighting as described above, addition or subtraction of a predetermined value can be used for weighting.
[flowchart]

  FIG. 15 is a flowchart of the wireless LAN communication apparatus 301 according to the present embodiment. Since the steps other than S1501 have been described in other embodiments, the description will be simplified.

  In S403, an access point that is a roaming candidate is selected.

  In step S409, it is determined whether the wireless LAN communication device 301 is moving. For this determination, not only the first embodiment but also the methods 2 and 3 can be used.

  In S1501, weighting is performed according to the table of FIG.

  In S405, the roaming target access point is determined.

  In S407, roaming processing is performed.

  In this embodiment, the roaming timing is controlled by weighting the radio wave intensity. However, in addition to this, the dynamic change of the roaming threshold described in the other embodiments can be combined.

  In the above description, the characteristic operation of the present embodiment has been described. As is apparent from the above description, in this embodiment, roaming can be performed more appropriately by weighting the received radio wave intensity according to the moving speed of the wireless LAN communication device 301. However, since the movement of the wireless LAN communication device 301 is an essential condition in this embodiment, the conventional problem of frequent roaming still remains when the wireless radio wave is stationary in an overlapping area. Therefore, in practice, it is desirable to use the present embodiment in combination with the first embodiment. FIG. 16 shows a graph when these are combined.

  FIG. 16 is a graph when the wireless LAN communication device 301 moves at 10 m / s or more, temporarily stops, and then starts moving again.

  The wireless LAN communication device 301 is initially connected to the access point X. After that, when the moving speed reaches 10 m / s or more (t1), each received radio wave intensity is weighted. As a result, it roams to the access point Y at t2. Next, when the wireless LAN communication device 301 enters a stationary state at t3, the weighting on the received radio wave intensity is released and simultaneously the roaming threshold decreases. As a result, frequent roaming can be avoided even when stationary. Thereafter, when the wireless LAN communication device 301 enters the moving state again at t4, the roaming threshold is increased, and at the same time, the received radio wave intensity is weighted.

  In addition, as another solution when stationary, a weighting coefficient when stationary (speed is 0) can be determined. That is, when stationary, the access point X being connected may be weighted by + 30%, and the access point Y to be roamed may be weighted by -30%. Of course, this case can also be combined with the first embodiment.

In this embodiment, the weighting coefficient exists for each speed category of the moving speed of the wireless LAN communication apparatus 301. However, the weighting coefficient is not necessarily required for each speed category, and may be a unique value determined by a function for the moving speed.
[effect]

As described above, it is possible to perform roaming more appropriately by weighting the received radio wave intensity according to the moving speed of the wireless LAN communication device 301. For example, when the speed is low, the connection with the connected access point is maintained and stable communication is continued. Conversely, when the speed is high, the access point to which the wireless LAN communication device 301 is connected is determined. Weighting is performed to speed up roaming based on the assumption that the vehicle will leave the covered area at an early stage. In this way, the timing can be shifted so that roaming is performed before or after passing through an area where frequent roaming occurs normally. Also, by combining with the first embodiment, frequent roaming can be avoided when the received radio wave is stationary in an overlapping area.
<Other embodiments>

  In the above-described embodiment, the information from the sensor such as the acceleration sensor is determined to move downward, the roaming threshold is changed, or the received radio wave intensity is weighted. However, such a sensor is not always necessary. If the wireless LAN communication apparatus 301 can detect its own movement by some means, these processes can be performed. For example, a human may perform a movement determination and manually input this information into the wireless LAN communication device 301. Further, the sensor to be used is not limited to the acceleration sensor, and any sensor that can detect movement may be used. Furthermore, it is possible to detect movement by combining a plurality of sensors such as an acceleration sensor and a gyro sensor.

  Regarding roaming, in the first to fourth embodiments, roaming is performed when the radio wave being connected falls below the roaming threshold and a stronger radio wave is received from another access point at that time. Roaming may be performed when the radio wave from an access point that is not roaming exceeds the roaming threshold and the radio wave intensity from the roaming target AP is higher than the radio wave that is currently connected. In this case, the roaming threshold value corresponding to the moving state of the wireless LAN communication device 301 is low, and a value that facilitates roaming more frequently is set, while the roaming threshold value corresponding to the stationary state is high and makes roaming difficult. Value is set.

  With respect to the scope of application, the present invention is not limited to the above-described wireless LAN communication device, but can be applied to any wireless communication device that performs communication with a base station and roaming, such as a mobile phone.

Received radio wave intensity when the wireless LAN communication device moves Received signal strength in areas where received signals overlap FIG. 1 is a block diagram of an apparatus according to the first embodiment. Operation flow of the apparatus according to the first embodiment Relationship between received radio wave intensity and roaming threshold in the first embodiment Outline of Movement of Wireless LAN Communication Device in Embodiment 1 Movement determination in the second embodiment Operation flow in Embodiment 2 Received radio wave intensity of wireless LAN communication device in embodiment 3 Variance value of received radio wave intensity of wireless LAN communication apparatus in embodiment 3 Operation flow in Embodiment 3 Weighting coefficient for received radio wave intensity in embodiment 4 Weighting with respect to received radio wave intensity in the fourth embodiment Weighting with respect to received radio wave intensity in the fourth embodiment Operation flow in Embodiment 4 Relationship between received radio wave intensity and roaming threshold in embodiment 4

Explanation of symbols

315 Movement detection means 317 Roaming threshold setting means

Claims (10)

A movement detecting means for determining whether the wireless communication device is moving based on information from the predetermined means;
When the information from the movement detection means indicates the movement of the wireless communication device, the roaming threshold is set so that the roaming is easier than the information indicating the stationary state, and the information indicates the stationary state Roaming threshold value setting means for setting a roaming threshold value to make roaming more difficult than in the case of information indicating movement;
A wireless communication device comprising: The wireless communication apparatus according to claim 1, wherein the predetermined means is an acceleration sensor. The movement detecting means acquires a plurality of speed vectors of the wireless communication device within a predetermined time as information from the predetermined means, and a magnitude of a combined vector of the plurality of acquired speed vectors within the predetermined time is a predetermined value The wireless communication apparatus according to claim 1, wherein when it is larger, it is determined as moving, and when it is not, it is determined as stationary. The predetermined means records a plurality of radio wave intensities from the access point received by the wireless communication apparatus for each access point within a predetermined time, and moves the dispersion value for a predetermined number of times of the recorded radio wave intensity To the detection means,
The wireless communication device according to claim 1, wherein the movement detection unit determines that the movement is detected when at least one of the dispersion values is greater than a predetermined value, and determines that the movement is stationary otherwise. A moving speed detecting means for detecting a moving speed of the wireless communication device based on information from the predetermined means;
For the purpose of controlling the timing of roaming, the moving speed of the wireless communication device detected by the moving speed detecting means is set in advance with respect to the strength of the radio wave from the connected access point and the radio wave from the non-connected access point. A weighting means for weighting an associated weighting factor;
A wireless communication device comprising: The wireless communication device further includes:
Based on the moving speed of the wireless communication device detected by the moving speed detection means, it is determined whether the wireless communication device is moving or stationary, and if it is determined that the wireless communication device is moving, The roaming threshold is set so that it is easier to roam than when it is determined that it is moving, and when it is determined that it is stationary, the roaming threshold is set so that it is less likely to roam than when it is determined that it is moving. The wireless communication apparatus according to claim 5, further comprising roaming threshold setting means for setting. A computer equipped with a wireless communication device;
A movement detection means for determining whether the wireless communication device is moving based on information from the predetermined means;
When the information from the movement detection means indicates the movement of the wireless communication device, the roaming threshold is set so that the roaming is easier than the information indicating the stationary state, and the information indicates the stationary state Roaming threshold setting means for setting a roaming threshold so as to make roaming more difficult than in the case of information indicating movement;
Program to make it work. The program according to claim 7, wherein the predetermined means is an acceleration sensor. A computer equipped with a wireless communication device;
A moving speed detecting means for detecting a moving speed of the wireless communication device based on information from the predetermined means;
For the purpose of controlling the timing of roaming, the moving speed of the wireless communication device detected by the moving speed detecting means is set in advance with respect to the intensity of the radio wave from the connected access point and the radio wave from the non-connected access point. A weighting means for weighting the associated weighting factor;
Program to make it work. The program further includes a computer provided in the wireless communication device.
Based on the moving speed of the wireless communication device detected by the moving speed detection means, it is determined whether the wireless communication device is moving or stationary, and if it is determined that the wireless communication device is moving, The roaming threshold is set so that it is easier to roam than when it is determined that it is moving, and when it is determined that it is stationary, the roaming threshold is set so that it is less likely to roam than when it is determined that it is moving. The program according to claim 9, wherein the program functions as roaming threshold setting means for setting.