JP4881166B2 - Wireless communication device - Google Patents

Description

  In an environment where a plurality of wireless communication repeaters can be accessed, the present invention reduces the access targets by narrowing down the wireless communication repeaters with unstable access conditions, thereby reducing the access targets. The present invention relates to a wireless communication apparatus capable of performing stable wireless communication.

  Conventionally, wireless communication based on various standards has been performed, and one of them is a wireless LAN (for example, IEEE802.11 system). In a communication system called a wireless LAN infrastructure mode, a wireless LAN terminal establishes a connection to an access point corresponding to a wireless communication repeater and performs wireless communication.

  In general, when an instruction to perform wireless communication is not issued from the user, the wireless LAN terminal enters a standby state, and the wireless LAN terminal in the standby state receives beacons emitted at regular intervals from the access point. A beacon is a signal for synchronizing wireless communication. By receiving a beacon emitted from an access point, the wireless LAN terminal recognizes the location of the access point to be connected.

  When a wireless LAN terminal tries to start wireless communication from a standby state, a carrier (carrier wave) that carries data so as not to collide with other wireless LAN terminals that communicate with the same access point at the same time The carrier sense is performed to check whether the data has already been stored in the device, that is, whether the carrier is in use. There are a method in which the carrier sense is continuously performed for a predetermined time and a method in which the carrier sense is intermittently performed with a certain interval time.

  In the carrier sense, a plurality of types of detection processes are performed. In the case of a wireless LAN, detection of carrier strength and detection of noise components included in the carrier (carrier power / noise power, hereinafter referred to as C / N ratio). , Detection of the number of receptions of CTS (Clear to Send) is performed. CTS means a signal (reception preparation completion signal) transmitted to prevent confusion when a plurality of wireless LAN terminals simultaneously perform wireless communication. In wireless LAN, RTS (Request to Send transmission request signal) When a wireless LAN terminal that intends to start wireless communication in preparation for transmission transmits a CTS and the other wireless LAN terminal receives the CTS, the other wireless LAN terminal stipulates that the other wireless LAN terminal refrains from communication until the next communicable time. It has become.

In Patent Document 1 below, when a wireless LAN terminal is located at a location where a plurality of access points can be accessed, the electric field strength for each access point is detected, and the access point that is the connection destination according to the detected electric field strength Has been disclosed (paragraph 0053, paragraph 0077, etc.).
JP 2004-320132 A

  As shown in FIG. 14, the number of places where the wireless LAN terminal 1 can access a large number of access points AP1 to AP5 has increased with the increase in the number of wireless LAN access points. The wireless LAN terminal 1 located in such a location recognizes the existence of each access point AP1 to AP5 based on the beacon transmitted from each access point AP1 to AP5, and sequentially performs a carrier scan to each access point AP1 to AP5. The access status (access stability) of each access point AP1 to AP5 is detected.

  The detected result is usually displayed as an access status screen 3 on the display unit 2 of the wireless LAN terminal 1 as shown in FIG. On the access status screen 3 shown in FIG. 15, access point columns 3a to 3e representing the access status for each of the accessible access points AP1 to AP5 are arranged to be selectable, and the access point columns 3a to 3e are not accessed. It is a word describing stability (good, ordinary, evil, unstable) and icon 4. Further, the specification is such that an access point corresponding to the selected column from among the access point columns 3a to 3e is specified as the connection destination of the wireless LAN.

  In selecting an access point, in order to perform wireless communication stably, it is important to identify an access point having a stable access status by removing an access point having an unstable access status from a selection target. However, in the conventional wireless LAN terminal 1, as shown in FIG. 15, since all accessible access points are represented regardless of the stability of access, it is difficult to find an access point with a stable access situation. is there. Furthermore, since the number of displayed access points increases as the number of access points that can be accessed increases, a problem arises that the burden on the user for determining the connection destination from among the many access points becomes excessive.

  In a wireless LAN, the stability of the access status to an access point varies from time to time depending on the surrounding environment at that time. For example, when there are many wireless LAN terminals that are trying to perform wireless communication at the same time, or when a physical obstacle is located between the wireless LAN terminal and the access point, the access point The access situation to becomes unstable. Such fluctuations in the stability of the access status make it more difficult to determine the access point used for the connection destination. Since Patent Document 1 relates to a handover of an access point as a connection destination, an access state that is unstable is cut out from a plurality of accessible access points, and an access point that is stable is easily obtained. Can't contribute to making it selectable.

  Also, it is necessary to identify and select an access point when performing carrier scan and when searching for another access point because the access status of the access point to which it is connected becomes unstable during wireless communication. It becomes. The above-described problems related to wireless communication have been described mainly for wireless LANs, but other wireless communication standards (for example, Wireless USB, UWB (Ultra Wide Band), Wireless 1394, etc.) that perform wireless communication through a wireless communication repeater are also used. It can occur as well.

  The present invention has been made in view of such a problem, and in a situation where a plurality of wireless communication repeaters can be accessed, a wireless communication connection destination can be selected by excluding those having unstable access conditions. It is an object of the present invention to provide a wireless communication apparatus that can easily perform the above.

  In order to solve the above-described problem, a wireless communication device according to the present invention includes a detection unit that detects an accessible wireless communication repeater in the wireless communication device that performs wireless communication by accessing a wireless communication relay, and the detection When the means detects a plurality of wireless communication repeaters, a comparison means for comparing the access sensitivity of each wireless communication repeater with a reference level, and a wireless with an access sensitivity not exceeding the reference level based on the comparison of the comparison means A specifying means for specifying whether or not there is a communication repeater, and when the specifying means specifies that there is a wireless communication repeater having an access sensitivity that does not exceed the reference level, the wireless communication repeater from the access target And an exclusion means for exclusion.

  In the present invention, when a plurality of accessible wireless communication repeaters are detected, the access sensitivity of each wireless communication repeater is compared with a reference level, and the wireless communication in which the access sensitivity specified based on the comparison does not exceed the reference level Since the relay device is excluded from the access target, only the remaining wireless communication relay device becomes the access target. As a result, the user only needs to identify and select the connection destination from among the wireless communication repeaters having a good level of access sensitivity that exceeds the reference level, so it is necessary to check all accessible wireless communication repeaters. As a result, the burden on the user related to determining and selecting the connection destination is reduced. Note that the standard level is to select a wireless communication destination that can perform wireless communication without any problems. The wireless communication status range is unstable (access status is unstable) and the stable range (access status is stable). It is preferable to set the reference level from the above boundary toward the stable range when it is desired to leave a more stable wireless communication destination as a selection target. is there. Therefore, it is preferable that the reference level can be changed as appropriate according to the usage pattern of the user.

  In addition, the wireless communication device according to the present invention includes a display unit and information indicating a wireless communication relay device having an access sensitivity exceeding the reference level among the plurality of wireless communication relay devices detected by the detection unit. And a means for performing a display process so as to be selectable.

  In the present invention, since the information indicating the remaining wireless communication repeaters that are not excluded is displayed in a selectable manner, the user can see a list of wireless communication repeaters that can be used as connection destinations by looking at the display contents. In addition to being able to confirm at a glance, it is easy to identify the wireless communication repeater to be selected as the connection destination. The information indicating the wireless communication repeater includes characters, icons, etc. expressed so that each wireless communication repeater can be identified, and characters, icons, etc. indicating the access status related to each wireless communication repeater are also included. Shall be included.

  Furthermore, the wireless communication apparatus according to the present invention is characterized in that the detecting means detects an accessible wireless communication repeater when performing carrier sense.

  In the present invention, since the wireless communication repeater that can be accessed is detected at the time of carrier sense, when performing carrier sense, the selection burden related to the connection destination that needs to determine the access status of the wireless communication repeater is reduced. Can be reduced.

  Still further, in the wireless communication device according to the present invention, a selection receiving unit that receives a selection of a wireless communication relay to be accessed from a wireless communication relay remaining from exclusion by the exclusion unit, and the selection receiving unit receives a selection. It comprises carrier sense means for carrying out carrier sense for a wireless communication repeater.

  In the present invention, carrier sense is performed on the wireless communication repeater that has received a selection from the remaining wireless communication repeaters, so the wireless communication repeater subject to carrier sense has an unstable access situation. Wireless communication repeaters are naturally excluded, and stable carrier sense can be performed.

  In the wireless communication apparatus according to the present invention, the carrier sensing means includes means for performing intermittent carrier sensing, and the intermittent time for intermittent carrier sensing performed by the carrier sensing means is determined as the wireless communication repeater. It is characterized by comprising changing means for changing according to the access sensitivity.

  In the present invention, the carrier sense is intermittently performed, and the intermittent time related to the intermittent carrier sense is changed according to the access sensitivity related to the wireless communication repeater that has accepted the selection. The intermittent time is appropriately changed according to the current wireless communication environment, and as a result, it is possible to reduce the power consumption of the wireless communication device and increase the efficiency of wireless communication in intermittent carrier sense. For example, when the wireless communication environment is the minimum situation where stable wireless communication is possible, the connection with the wireless communication repeater is relatively difficult to establish, so if the intermittent time is made longer than the default reference time Thus, it is possible to prevent the carrier sense from being repeated unnecessarily at short intervals, and accordingly, power consumption due to the carrier sense can be suppressed. On the other hand, if the wireless communication environment is good, it is easy to establish a connection with the wireless communication repeater, so if the intermittent time is shorter than the default reference time, the connection with the wireless communication repeater is established immediately. Therefore, it is possible to quickly shift to substantial wireless communication and perform efficient wireless communication.

  The wireless communication apparatus according to the present invention is characterized in that the detection means performs detection when establishing a connection with one wireless communication repeater.

  In the present invention, when a connection with one wireless communication repeater is established, another accessible wireless communication repeater is detected, so one wireless communication repeater with established connection is established. When the access status of the user deteriorates and it becomes necessary to search for another connection destination, the burden on the user related to selection of the connection destination can be reduced.

  The wireless communication apparatus according to the present invention is characterized in that the comparison means compares the number of receptions of a reception preparation completion signal related to wireless communication with a reference level as an access sensitivity related to the wireless communication repeater.

  In the present invention, since the number of receptions of the reception preparation completion signal (for example, CTS in the wireless LAN standard) is used as the access sensitivity related to the wireless communication repeater, wireless communication is performed based on the number of receptions of the reception preparation completion signal. The access sensitivity related to the repeater is determined by comparison. As a result, by reflecting the wireless communication status of other wireless communication repeaters existing in the vicinity, the current access sensitivity can be compared with the reference level, and wireless communication repeaters with poor access sensitivity can be excluded from access targets.

  When the number of times of reception preparation completion signal reception is used as the access sensitivity, the reference level used as a reference for comparison should be a level value (threshold) that can determine the access sensitivity according to the number of reception preparation reception signals received. become. In addition, as the number of reception preparation completion signals is increased, the number of other wireless communication devices that attempt to perform wireless communication at the same time exists in the surrounding area, so the degree of congestion of wireless communication increases and the access status (access sensitivity) is increased. The access status (access sensitivity) improves as the number of reception preparation completion signal receptions decreases. Therefore, when the number of times of reception preparation completion signal reception is used as the access sensitivity, a wireless communication repeater whose access sensitivity does not exceed the reference level is a threshold (for example, “2”) in which the number of reception of the reception preparation completion signal is related to the reference level. More is the case.

  The wireless communication apparatus according to the present invention is characterized in that the comparison means compares a value related to a noise component of a carrier wave of the wireless communication repeater with a reference level as an access sensitivity related to the wireless communication repeater.

  In the present invention, since the value (for example, C / N ratio) related to the noise component of the carrier is used as the access sensitivity related to the wireless communication repeater, the wireless communication repeater is used based on the noise component included in the carrier. Such access sensitivity is compared and judged. As a result, a wireless communication repeater that emits a carrier wave with a large noise component can be excluded from access targets. When the value related to the noise component of the carrier is used as the access sensitivity, the level value (reference value) of the reference level serving as a reference for comparison can also determine the access sensitivity according to the value related to the noise component of the carrier. Apply. Also, the smaller the C / N ratio, which is an example of the value related to the noise component of the carrier wave, the more noise components are contained in the carrier and the worse the access status (access sensitivity), and the higher the C / N ratio, Since there are few noise components included, the access situation (access sensitivity) is improved. Therefore, when the value related to the noise component of the carrier wave is used for the access sensitivity, the wireless communication repeater whose access sensitivity does not exceed the reference level is lower than the value related to the reference level (reference value). The thing corresponds.

  The wireless communication apparatus according to the present invention is characterized in that the comparison means compares the power intensity of the carrier wave of the wireless communication repeater with a reference level as an access sensitivity related to the wireless communication repeater.

  In the present invention, since the power intensity of the carrier wave is used as the access sensitivity related to the wireless communication repeater, the access sensitivity related to the wireless communication repeater is compared and determined based on the power intensity of the carrier wave. Thereby, a wireless communication repeater that emits a carrier wave with low power intensity can be excluded from access targets. When the power intensity of the carrier wave is used as the access sensitivity, a value (reference value) that can determine the access sensitivity according to the power intensity of the carrier wave is applied to the reference level as a reference for comparison. Further, the smaller the carrier power intensity, the worse the access situation (access sensitivity), and the higher the carrier power intensity, the better the access situation (access sensitivity). Therefore, when the power intensity of the carrier wave is used for the access sensitivity, the wireless communication repeater in which the access sensitivity does not exceed the reference level corresponds to a wireless communication relay device in which the power intensity of the carrier wave is lower than a value (reference value) related to the reference level.

  In the present invention, the user only has to select a connection destination from wireless communication repeaters having a certain access sensitivity with good access conditions, and when the user can access a plurality of wireless communication repeaters. It is possible to reduce a user burden related to selection of a connection destination for wireless communication.

  In the present invention, since information indicating a wireless communication repeater having an access sensitivity exceeding the reference level is displayed in a selectable manner, the wireless communication repeater in which the access status is not unstable can be confirmed at a glance and confirmed. From among them, a wireless communication repeater according to the user's preference can be easily selected as a connection destination.

  In the present invention, when performing carrier sense, an accessible wireless communication repeater is detected, so that a connection destination used for carrier sense can be easily selected.

  Also, in the present invention, carrier sense is performed for the wireless communication repeater that has accepted the selection from the remaining wireless communication repeaters due to the exclusion, so that the wireless communication repeater with unstable access status is detected by carrier sense. Can be reliably removed from the selection target, and carrier sense can be stably performed.

  Furthermore, in the present invention, the carrier sense is intermittently performed, and the intermittent time related to the intermittent carrier sense is changed according to the access sensitivity related to the wireless communication repeater that has accepted the selection. This makes it possible to reduce the power consumption of the wireless communication device and improve the efficiency of wireless communication in a simple carrier sense.

  Furthermore, in the present invention, even when the access status of the wireless communication repeater at the connection destination deteriorates and it becomes necessary to search for another connection destination, the burden on the user related to the selection of the connection destination can be reduced.

  In the present invention, since the number of receptions of the reception preparation completion signal (for example, CTS in the wireless LAN standard) is used as the access sensitivity related to the wireless communication repeater, wireless communication is performed based on the number of receptions of the reception preparation completion signal. Access sensitivity related to repeaters can be compared and judged.

  In the present invention, since the value related to the noise component of the carrier is used as the access sensitivity related to the wireless communication repeater, the access sensitivity related to the wireless communication repeater is compared and determined based on the noise component included in the carrier. it can.

  Furthermore, in the present invention, since the power intensity of the carrier wave is used as the access sensitivity related to the wireless communication repeater, the access sensitivity related to the wireless communication repeater can be compared and determined based on the power intensity of the carrier wave.

  FIG. 1 shows a main internal configuration of a portable music playback device 10 incorporating a wireless LAN module (corresponding to a wireless communication device) 20 according to an embodiment of the present invention. The portable music playback device 10 is characterized by having a wireless LAN communication function in addition to the original music playback function, and has a built-in wireless LAN module 20 corresponding to the wireless LAN communication function. It is connected to the main module 11 corresponding to the music playback function. The portable music player 10 can easily acquire various music data via wireless LAN communication, and the acquired music data can be reproduced and output by the main module 11.

  When the wireless LAN module 20 included in the portable music player 10 performs wireless communication in the infrastructure mode, as shown in FIG. 14, for example, each access point AP1 to AP5 can be accessed. It is characterized by detecting the access status of points, automatically excluding access points with unstable access status from the connection targets, and only the remaining access points as connection targets. The wireless LAN module 20 is designed to detect the access status associated with each access point when performing carrier sense and when the access status of an access point established during wireless communication becomes unstable. . Since each access point emits a beacon including an SSID (corresponding to a service set identifier identification signal), the wireless LAN module 20 allows each of the access points AP1 to AP5 to be connected even in the situation shown in FIG. It is possible to identify and detect whether or not there are a plurality of accessible access points, and to determine the access sensitivity for each access point.

  In addition, the wireless LAN module 20 of the present embodiment intermittently performs carrier sense, and at the time of carrier sense, automatically changes the intermittent time of carrier sense (corresponding to the interval time) in conjunction with the current access status, Reduces power consumption and improves wireless communication efficiency during carrier sense. Hereinafter, the portable music player 10 according to the present embodiment will be described in the order of the main module 11 and the wireless LAN module 20.

  The main module 11 shown in FIG. 1 has a configuration in which a RAM 12, a ROM 13, a storage unit 14, an audio output processing unit 15, a main control unit (processor) 17, a display panel 18, and an operation unit 19 are connected through internal buses 11a and 11b. ing. The RAM 12 temporarily stores data and files associated with the processing of the main control unit 17, and the ROM 13 stores in advance a playback program 13a defining control processing for music playback, playback menu data 13b for performing music selection, and the like. is doing. The memory | storage part 14 memorize | stores the music data D acquired via wireless LAN communication. The audio output processing unit 15 performs processing for outputting audio from the speaker 16 by performing reproduction processing and amplification of music data.

  The main control unit 17 connects the display panel 18 and the operation unit 19. The display panel 18 displays a menu screen based on various menu data under the control of the main control unit 17, and a list showing the access stability of each access point when access to a plurality of access points is possible. The operation unit 19 includes a plurality of keys such as up / down / left / right keys and an enter key. The operation unit 19 receives a user's selection instruction for a selection item on the menu screen, and sends the received instruction content to the main control unit 17. Tell. The main control unit 17 performs control processing related to the reproduction of music data (for example, music data of an MP3 file) in accordance with the regulations of the reproduction program 13a stored in the ROM 13, and performs various setting processes, etc. By linking with the wireless LAN module 20, processing related to wireless LAN setting is also performed.

  On the other hand, the wireless LAN module 20 performs wireless LAN communication (IEEE802.11, IEEE802.11a, IEEE802.11b, IEEE802.11g, IEEE802.11k, etc.) defined by the American Institute of Electrical and Electronics Engineers, and is made into a chip. The wireless LAN has an RF (high frequency) circuit unit 21 and a MAC processing unit 25.

  The RF circuit unit 21 corresponds to a physical layer in the OSI reference model, and is connected to a wireless LAN antenna 24, and performs various processes such as frequency conversion, I / Q conversion, and amplification of received signals. In addition, the RF circuit unit 21 detects the carrier power intensity related to the access point at the time of carrier sensing, and detects the carrier C / N ratio (carrier power / noise power) as a noise component in the carrier. A C / N detection circuit 23 is included. The RF circuit unit 21 is controlled with respect to the operation by the CPU 27 included in the MAC processing unit 25, and starts the operation in accordance with the carrier sense process. The strength detection circuit 22 detects the power strength of the carrier in the range of about −80 dBm to about −10 dBm as the access sensitivity related to each access point.

  Note that the C / N ratio (a value related to a noise component in a carrier wave) that is a detection target of the C / N detection circuit 23 varies depending on surrounding conditions. That is, when the propagation path of wireless LAN communication is a multi-wave propagation path, if interference or the like occurs in the communication wave of the wireless LAN due to the reflection of the building and the communication wave emitted from an access point existing in the vicinity, The level fluctuates (fading phenomenon). In addition, the frequency shift of the carrier wave occurs due to the movement of the transceiver and the reflector that perform wireless LAN communication. Due to such fading phenomenon and frequency shift, the original C / N ratio cannot be secured on the receiving side, which causes the C / N ratio to fluctuate.

  The MAC processing unit 25 shown in FIG. 1 has a configuration in which a memory 26, a CPU 27, a connection interface 28 for connecting to the main module 11, an RF connection interface 29 for connecting to the RF circuit unit 21, and the like are connected by an internal bus 25a. In the wireless LAN communication, processing such as digital conversion / demodulation and access control is performed. The CPU 27 has a built-in clock function, and performs various controls described later according to the time to be timed.

  The memory 26 includes a program P that defines various contents of control processing related to wireless LAN communication performed by the CPU 27, menu data 33, and reference value data 34 for comparison with the carrier power intensity detected as the access sensitivity of each access point. Further, a display table 35, a setting table 40 in which the value of the intermittent time of the carrier sense is associated with each level of the wireless LAN environment based on the power intensity of the carrier are stored.

  The reference value data 34 stored in the memory 26 is a first reference value (corresponding to a reference level) 34a used when truncating an access point having a poor access status (access sensitivity) from a plurality of accessible access points. Contains. Further, the reference value data 34 includes a second reference value 34b and a third reference value 34c as reference values corresponding to each access state of the access point in order to automatically change the intermittent time during carrier sense.

  In the present embodiment, as an example, “−70 dBm” is set as the first reference value 34a, and “−50 dBm” is set as the second reference value 34b, and “−30 dBm” is set as the third reference value 34c. ing. The third reference value 34c is a boundary value that distinguishes between the good level and the normal level in the wireless LAN environment (access status) related to the access point to be accessed, and the second reference value 34b is the normal level. It is a boundary value that distinguishes the evil level. Of course, the values of the reference values 34a to 34c can be changed as appropriate according to the user's convenience.

  Each of the reference values 34a to 34c is regulated by the program P stored in the memory 26 to be compared by the CPU 27 with the power intensity of the carrier related to the access point detected by the intensity detection circuit 22. If the power intensity generated from the target access point does not exceed the first reference value 34a (for example, if it is equal to or lower than the first reference value 34a), the program P also defines that the access point is excluded from the access target. Yes. If the carrier power intensity detected for the access point to be accessed exceeds the third reference value 34c, the CPU 27 determines that the access status is a good level, exceeds the second reference value 34b, and exceeds the third reference value 34c. The program P also stipulates that when the value is 34c or less, it is determined as a normal level, and when it exceeds the first reference value 34a and is equal to or less than the second reference value 34b, it is determined as a bad level. In order to easily change the interval time for each level determined in this way, a setting table 40 is stored in the memory 26.

  FIG. 4 shows the contents of the setting table 40 stored in the memory 26. In the setting table 40, the numerical value for the interval time of intermittent carrier sense is associated with each of the above-described good level to bad level, and specifically, the good level is 10 seconds (corresponding to the first time). ), The normal level is associated with 5 seconds (corresponding to the second time), and the bad level is associated with 40 seconds (corresponding to the third time) by default. The numerical value for the interval time according to each level can be changed appropriately on the menu screen, the good level can be changed in the range of 10 to 29 seconds, the normal level can be changed in the range of 1 to 9 seconds, and the bad level is Although it can be changed in the range of 30 seconds to 50 seconds, the numerical values of these times are merely examples, and various numerical values can be applied according to the characteristics, specifications, etc. of the product.

  The concept of the setting contents for each level in the setting table 40 described above will be explained. First, a good level where the wireless LAN environment is “good” is a state in which a connection can be established immediately if a connection with an access point is attempted. Therefore, the interval time can be set within the range of 10 seconds to 29 seconds so that the carrier sense frequency is suppressed to some extent and the connection state is about the same as the normal level. In addition, the normal level where the wireless LAN environment is “normal” can be connected to the access point at the normal level, and in order to ensure a connection status (probability of connection) equivalent to the good level, it is shorter than the good level for 1 second. The interval time can be changed in the range of 9 seconds from the beginning. With such setting contents, if the wireless LAN environment is at a normal level or higher, it is possible to always provide the same connection status to the user, and the user can perform wireless communication with a certain connection probability without being aware of the wireless LAN environment. Yes.

  Furthermore, the evil level in which the wireless LAN environment is “bad” is that the access status to the access point is a little unstable, and is a lower limit that satisfies the user satisfaction by maintaining an acceptable communication level of wireless communication. Priority is given to reducing power consumption by performing carrier sense at a frequency at which the wireless LAN communication environment is detected at a minimum, and the interval time is set within the range of 30 seconds to 50 seconds. . The situation below the first reference value 34a excluded from the access target corresponds to a level at which a normal communication with the wireless communication destination can no longer be expected.

  FIG. 3 shows an access point list screen 36 generated based on the display data 35 stored in the memory 26. The access point list screen 36 is generated under the control of the CPU 27 using an icon or the like included in the display data 35, and the generated content is sent from the connection interface 28 (corresponding to the output means) of the MAC processing unit 25 to the main module 11. To be displayed on the display panel 18. The access point list screen 36 includes an access point column 36a as information indicating access points remaining after an access point whose carrier power intensity is equal to or lower than the first reference value 34a is excluded from a plurality of accessible access points. 36b can be selected.

  The access point list screen 36 does not show an access point whose access status is unstable compared to the access status screen 3 of FIG. 15, so an access point that can withstand use even in a location where a plurality of access points can be accessed. Thus, the burden on the user's access point selection is reduced. As in the access status screen 3 of FIG. 15, the access point list screen 36 corresponds to the selected access point column when any of the access point columns 36a and 36b is selected by the operation of the operation unit 19. The access point is specified as the connection destination of the wireless LAN.

  The program P stored in the memory 26 defines the contents of control processing when the CPU 27 performs various processes related to wireless communication. In this embodiment, in addition to basic wireless LAN communication and the like, the above-described program P is stored. Thus, when it is possible to access a plurality of access points, which is a feature of the present invention, a control process for displaying the access point list screen 36 of FIG. 3 is performed, an interval time change process in intermittent carrier sense, etc. Is stipulated. The contents of the basic wireless LAN communication process defined by the program P include starting intermittent carrier sense when an instruction to perform wireless communication related to data transmission / reception is received from the user. Yes.

  Specific processing contents of the program P relating to the present invention are as follows. First, the program P prescribes that the CPU 27 detects whether or not there are a plurality of access points based on beacons emitted from each access point. When a plurality of access points are detected, the first reference value is obtained by using the power intensity of the carrier related to each access point detected by the strength detection circuit 22 of the RF circuit unit 21 when the CPU 27 performs carrier sense as the access sensitivity. Compared to 34a, a process of excluding from a plurality of accessible access points that do not exceed the first reference value 34a (in this embodiment, the first reference value 34a or less) is performed. In this case, the CPU 27 further generates an access point list screen 36 (see FIG. 3) in which information indicating access points remaining after the exclusion is arranged so as to be selectable, and displays the information on the display panel 18.

  Further, upon accepting selection of one of the access point fields 36a and 36b on the access point list screen 36 by operating the operation unit 19, the CPU 27 performs access to intermittently sense the access point in the selected access point field. Identify as a target. Furthermore, the CPU 27 compares the power intensity of the carrier related to the identified access point with the second reference value 34b and the third reference value 34c, and based on the comparison result, the level of access sensitivity of the access point (good, normal, bad) 4 is determined from the setting table of FIG. 4 and the determined time is specified as an intermittent carrier sense interval time. To do. Thereafter, the CPU 27 is determined by comparing the power intensity of the carrier detected by the intensity detection circuit 22 with each of the reference values 34b and 34c in the time zone in which the carrier sense is performed while continuing the intermittent carrier sense. Control to change the interval time to time.

  The CPU 27 performs the process related to the time change for each time period for performing carrier sense in the overall intermittent carrier sense, and sets the interval time after each carrier sense time period according to the wireless LAN environment. Change automatically. If only one access point can be detected and the power intensity of the carrier of the one access point is equal to or lower than the first reference value 34a, the access point must rely on connection. Therefore, the CPU 27 performs control to perform intermittent carrier sense for the access point. In this embodiment, when the power intensity of the carrier related to the one access point exceeds the first reference value 34a, the CPU 27 detects again whether there are a plurality of access points.

  In the present invention, the CPU 27 corresponds to a part of the data link layer of the MAC layer (Media Access Control OSI reference model) defined by CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) by software processing of the program P. ) Is also functioning.

  FIG. 2 conceptually shows the content that the CPU 27 functions as the MAC layer 30. The MAC layer 30 defines an access method (for example, CSMA / CA) based on the IEEE (American Institute of Electrical and Electronics Engineers) wireless LAN standard (IEEE802.11 standard). Among them, an UpperMAC 31 corresponding to the upper layer and a LowerMAC 32 corresponding to the lower layer are provided. Further, the Upper MAC 31 includes a CTS number detection block 31a and a carrier number detection block 31b.

  The CTS number detection block 31a functions as a means for counting and detecting the number of receptions of CTS (reception preparation completion signal) issued from another wireless device during carrier sensing. The carrier number detection block 31b counts the number of accessible access points based on an identification signal (a signal included in a beacon) issued from each access point, and detects whether there are a plurality of access points. Functions as a means. Note that the program P stored in the memory 26 adjusts the operation of the portion that functions as the MAC layer 30 of the CPU 27 and the operation of the RF circuit unit 21 to the interval time in order to realize power saving at the interval time in intermittent carrier sense. It also stipulates that it be stopped. In the present embodiment, the MAC layer 30 and the RF circuit unit 21 correspond to access control means for performing access control related to wireless communication.

  The first flowchart shown in FIG. 5 is an arrangement of processing procedures related to access point exclusion of the wireless LAN module 20 (CPU 27) when performing intermittent carrier sensing. The contents of excluding access points whose access status is unstable when a plurality of access points can be accessed will be described step by step according to the first flowchart.

  First, the wireless LAN module 20 receives a beacon issued by an access point, detects whether there are a plurality of access points (S1), and detects that there are a plurality of access points (S1: YES), the carrier power intensity associated with each access point is compared with the first reference value 34a to determine whether there is an access point equal to or lower than the first reference value 34a (S2).

  When it is specified that there is an access point having the first reference value 34a or less (S2: YES), the wireless LAN module 20 excludes such an access point from the access target (S3). In addition, after exclusion, it returns to step (S2) of whether the access point below the 1st reference value 34a exists again. On the other hand, when it is specified that there is no access point equal to or lower than the first reference value 34a (S2: NO), the wireless LAN module 20 is information indicating an access point that exceeds the first reference value 34a (access sensitivity is stable). Is generated and displayed (S4). Then, when the selection of any one access point column is accepted on the displayed access point list screen 36, the wireless LAN module 20 identifies the access point related to the selection as an access target, and intermittently with respect to the access point. A typical carrier sense is performed (S6).

  When the number of access points detected by receiving a beacon is not plural but only one (S2: NO), the wireless LAN module 20 has the power intensity of the carrier related to the access point equal to or less than the first reference value 34a. If it is equal to or less than the first reference value 34a (S5: YES), there is no room for selection regarding the access point, so intermittent carrier sense is performed for the one access point. (S6). Further, when the power intensity of the carrier related to the one access point exceeds the first reference value 34a (S5: NO), it is determined that the connection can be made immediately if the connection to the access point is attempted, and the carrier scan is immediately performed. In step S1 for detecting the presence of a plurality of access points again, the wireless LAN environment (whether there are a plurality of access points) is continuously detected.

  Furthermore, in the present invention, in the step (S6) of performing the intermittent carrier scan in the first flowchart of FIG. 5 described above, the CPU 27 performs the change control of the interval time according to the access sensitivity of the access point performing the carrier scan, Control for stopping the access control part included in the wireless LAN module 20 in accordance with the interval time is also performed. Specifically, the operation of the part corresponding to the MAC layer 30 (refer to FIG. 2) and physical layer (in this embodiment, the RF circuit unit 21) defined by CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) Is stopped at the interval time to reduce power consumption for intermittent carrier sense.

  The program P defines the operation stop processing of the MAC layer 30 and the RF circuit unit 21 as follows. That is, the program P is controlled by the CPU 27 so as to stop the operation of the MAC layer 30 and the RF circuit unit 21 (including the strength detection circuit 22 and the C / N detection circuit 23) at the end of each carrier sense time period. It stipulates that this is done as a stopping means Even when the MAC layer 30 and the RF circuit unit 21 are not operating, the other parts of the wireless LAN module 20 are operating, and the wireless LAN module 20 consumes some power even at this time. Further, the program P stipulates that the CPU 27 performs the control for restarting the operation of the MAC layer 30 and the RF circuit unit 21 that have been stopped as the operation start means before a predetermined time when the interval time ends. .

  Further, the program P includes the Upper MAC 31, the Lower MAC 32, and the RF circuit unit 21 (intensity detection circuit 22) including the CTS number detection block 31 a and the carrier number detection block 31 b as usual in the time period of each carrier sense in intermittent carrier sense. And the C / N detection circuit 23) are operated to perform access control related to wireless LAN communication.

  FIG. 6 is a time chart graph showing an example of processing in the intermittent carrier scan step (S6) of the first flowchart of FIG. 5 under the control of the CPU 27 based on the definition of the program P. This graph shows a case where all 13 channels defined by IEEE802.11b are carrier sensed. In the graph, carrier scanning is performed for all channels in the time zone from time 0 to t10, t11 to t12, and t13 to t14. . In FIG. 6, one of the bar graphs represents carrier sense for one channel, and bar graphs corresponding to all 13 channels in each time zone in which carrier sense is performed are omitted. In addition, in each time zone in which carrier sense is performed, the MAC layer 30 and the RF circuit unit 21 are operated to perform CTS reception frequency count, access point number detection, carrier power intensity detection, and C / N ratio detection. A time period for performing carrier sense of all channels (time periods from time 0 to t10, t11 to t12, and t13 to t14) requires about 2 seconds. In the graph of FIG. 6, the time between carrier sensing time periods (t10 to t11, t12 to t13, t14 to t15, etc.) corresponds to the interval time, and thus the carrier sense is performed with the interval time interposed therebetween. Thus, carrier sense is intermittently performed.

  In the example of the graph of FIG. 6, the carrier power intensity detected in the time zone (time 0 to t <b> 10) in which carrier sense of all the first channels is performed is compared with the reference values 34 a to 34 c stored in the memory 26. This shows a case where the access sensitivity as a wireless LAN environment is determined to be “good”, and as a result, the interval time (time t10 to t11) immediately after the first carrier sense time zone is 10 seconds. (Refer to the setting table 40 in FIG. 4. The same applies hereinafter). Further, based on the comparison result in the time zone (time t11 to t12) in which the second carrier sense is performed, the wireless LAN environment in that time zone is determined to be “normal level”, thereby the second carrier sense time zone. The interval time (time t12 to t13) immediately after is changed to 5 seconds. Further, based on the comparison result in the time zone (time t13 to t14) in which the third carrier sense is performed, the wireless LAN environment in that time zone is determined to be “bad level”, thereby the third carrier sense time zone. The interval time immediately after (time t14 to t15) is changed to 40 seconds.

  Thus, in the present invention, after the wireless LAN environment (access status of the access point selected as an access target) is determined to be “good”, the interval time is set to 10 seconds (time t10 to t11), After the wireless LAN environment is determined to be “normal level”, the interval time shorter than the first level is changed to 5 seconds (time t12 to t13). Connection probabilities to points can be made equal, and the same communication level can always be provided without making the user aware of the wireless LAN environment. In addition, after the wireless LAN environment is determined to be “bad 3 level”, the interval time is set to 40 seconds (time t14 to t15). Therefore, in consideration of the low connection probability, priority is given to power saving in consideration of carrier sense. Perform the process. In addition, the wireless LAN module 20 synergistically achieves further power saving by stopping the operation of the MAC layer 30 and the RF circuit unit 21 during the varying interval time.

  Specifically, when the first carrier sense time period in the graph of FIG. 6 ends and time t10 (interval time start time) is reached, the MAC layer 30 and the RF circuit in the wireless LAN module 20 are controlled by the CPU 27. The part 21 stops operating. Further, when the time T11 (the end time of the interval time) comes before the time T11, the operation of the MAC layer 30 and the RF circuit unit 21 is resumed under the control of the CPU 27 to perform access control. As described above, in the wireless LAN module 20, since the operation of the MAC layer 30 and the RF circuit unit 21 is resumed at the time T before the end time of the interval time, the access control is surely performed when the next carrier sense is started. Thus, various detection processes can be performed without hindrance. The predetermined time is set in advance in the range of about 0.5 seconds to 2 seconds. Similarly, the MAC layer 30 and the RF circuit unit 21 repeat the operation stop and the operation restart in accordance with the time before the time T from the start time and end time of each interval time.

  As a result, since the wireless LAN module 20 of the present invention suppresses the operation level during the interval time, the power consumption during the interval time is reduced from the conventional AmW to BmW (B <A) to achieve power saving. In the graph of FIG. 6, the case where carrier sense is performed for all channels (13 channels) is shown, but the present invention can be applied even when intermittent carrier scan is performed on any one of all channels. The same processing as that shown in the graph of FIG. 6 can be performed. Further, even when the carrier scan is not performed intermittently, it can be applied to processing (for example, processing related to the first flowchart in FIG. 5) except processing related to the graph of FIG. 6 (change of interval time, partial processing stop). It is.

  Furthermore, in the present embodiment, even when the connection with the access point is established, if the power intensity of the carrier related to the connected access point becomes equal to or lower than the first reference value 34a due to a change in the wireless LAN environment, The wireless LAN module 20 has a function of performing similar processing. That is, if there are a plurality of other access points with stable access while the access sensitivity of the access point connected during wireless communication has deteriorated, an access point list screen 36 as shown in FIG. And provides an opportunity for the user to easily select only access points that can be used stably.

  In the second flowchart shown in FIG. 7, when the access status of the connection destination access point becomes unstable while connected to one access point, a plurality of other access points can be accessed at that location. This is a summary of the processing procedure for selecting only the access points that can be used practically as the connection destination selection targets by excluding those with unstable access status from the accessible access points. is there. Hereinafter, the process during connection to the access point of the present invention will be described according to the second flowchart.

  First, the wireless LAN module 20 determines whether or not the power intensity of the carrier related to the connected access point is equal to or less than the first reference value 34a in order to confirm whether or not the connected access point is stable. (S10). When the access status is unstable because the power intensity of the carrier related to the connected access point is equal to or less than the first reference value 34a (S10: YES), the wireless LAN module 20 has an access point accessible at that location. Whether there are others is detected by receiving a beacon (S11). Then, the wireless LAN module 20 determines (detects) whether or not there are a plurality of accessible access points based on the identification signal included in the beacon (S12), and when there are a plurality of accessible access points (S12). : YES), the power intensity of the carrier related to each access point is compared with the first reference value 34a to specify whether or not there is an access point whose carrier power intensity is equal to or less than the first reference value 34a ( S13).

  When it is specified that there is an access point whose carrier power intensity is equal to or less than the first reference value 34a (S13: YES), the wireless LAN module 20 excludes such access point from the access target (S14). After the exclusion, the process returns to the step (S13) for determining whether there is an access point having the first reference value 34a or less. On the other hand, when it is specified that there is no access point equal to or lower than the first reference value 34a (S13: NO), the wireless LAN module 20 has the carrier power intensity exceeding the first reference value 34a and the access sensitivity is stable. An access point list screen 36 (see FIG. 3) on which information indicating the existing access points is placed is generated and displayed (S15). Further, when the wireless LAN module 20 accepts selection of any one access point on the access point list screen 36, the wireless LAN module 20 switches the connection to the access point related to the selection and performs wireless LAN communication (S16).

  When the connected access point is stable (S10: NO), there is no need to switch the connection, so the wireless LAN module 20 maintains the current connection (S17). Further, when there is no other access point that can be accessed (S11: NO), since there is no target for switching the connection, the wireless LAN module 20 maintains the current connection (S17).

  Further, when there is an access point but not a plurality (S12: NO), that is, when there is only one other access point that can be accessed, the wireless LAN module 20 uses the carrier related to the one access point. It is determined whether or not the power intensity is less than or equal to the first reference value 34a (S18). If the power intensity related to the one access point is equal to or less than the first reference value 34a (S18: YES), the wireless LAN module 20 maintains the current connection because there is no advantage over the connected access point. (S17). On the other hand, when the power intensity related to the one access point is not equal to or lower than the first reference value 34a (S18: NO), the wireless LAN module 20 has an advantage that the access sensitivity is good with respect to the connected access point. Switches the connection to the one access point and performs wireless LAN communication (S16).

  As described above, even when the connection to the access point is being established, if the access status of the connection destination access point becomes unstable, the present invention determines whether or not there are a plurality of access points that can be accessed in the vicinity. If it is detected and only a plurality of access points are present, only the access points that can be used stably are presented to the user (see S15 in the second flowchart and FIG. 3), so that the user can easily select a new connection target.

  The wireless communication apparatus according to the present invention is not limited to the form of the wireless LAN module 20 described above, and there are various modifications. First, the number of each of the reference values 34a to 34c included in the reference value data 34 used for determining the wireless LAN environment is not limited to three, and depends on the specification, grade, etc. of the wireless LAN module 20. Can be increased or decreased as appropriate. For example, when the number of reference values is more than three, the level of the wireless LAN environment that can be discriminated can be increased, and the power saving process and the carrier sense stop process that match the wireless LAN environment are performed by further finely dividing the level. Yes. On the other hand, when the number of reference values is less than 3, it is possible to reduce the processing load related to the level determination of the wireless LAN environment.

  Further, in the above description, regarding the exclusion of an access point having poor access sensitivity from a plurality of accessible access points and the change of the interval time of intermittent carrier sense, the value of the detected carrier power intensity However, as the access sensitivity, it is also possible to apply the detection result of the C / N ratio and the number of CTS receptions to the determination condition in addition to the power intensity. As described above, when other items (C / N ratio detection result or CTS reception count) are applied to the access sensitivity determination conditions, the reference values 34a to 34c stored in the memory 26 are also applied to the determination conditions to be applied. Make the content appropriate.

  Furthermore, it is also possible to exclude an access point with poor access sensitivity and to change the interval time of intermittent carrier sense in combination with a plurality of judgment conditions as access sensitivity. For example, a condition that combines the carrier power intensity and the C / N ratio is applied as the determination condition, and either the detected carrier power intensity or the C / N ratio for such a condition is the respective reference value. If it does not exceed, such an access point may be excluded from the access target as having low access sensitivity. Similarly, a combination of the carrier power intensity and the number of CTS receptions, the detection result of the C / N ratio and the number of CTS receptions, and the combination of the three types described above can be applied as judgment conditions.

  In addition, regarding the change of the interval time, when applying the above-described combination of determination conditions, it is necessary to use the content of the setting table stored in the memory 26 according to the combination to be applied.

  FIG. 8 shows a setting table 60 as an example of a setting table used when the carrier power intensity and the C / N ratio detection result are combined. The setting table 60 has each level (good level, normal level, bad level) determined based on the detected carrier power intensity, and each level (good level, normal level) determined based on the detection result of the C / N ratio. Level, evil level), and a value for interval time is set for each combination in which both are associated. By combining the two determination conditions in this way, the wireless LAN environment can be set in more detail, and an interval time can be assigned for each wireless LAN environment, and an interval time that further matches the actual wireless LAN environment can be set. You can make changes. When the setting table 60 as shown in FIG. 8 is used, three reference values for determining each level according to the power intensity of the carrier and 3 for determining each level according to the C / N ratio are used. Each of the two reference values needs to be stored in the memory 26. Further, the concept of time defined in the setting table 60 in FIG. 8 is basically the same as that in the setting table 40 shown in FIG. 4. At each level based on the carrier strength, a normal level based on detection of the C / N ratio. Time is the shortest, good time is the second shortest, and bad time is the longest.

  The setting table 61 of FIG. 9 shows an example of another setting table, and is used when the carrier power intensity and the number of CTS receptions (count) are combined as determination conditions. The setting table 61 associates, for each level (good level, normal level, bad level) determined based on the power intensity of the carrier, whether the number of CTS receptions (count) is greater than or less than the threshold for CTS, A numerical value for the interval time is set for each of these associations. Therefore, by using the setting table 61, it is possible to determine the wireless LAN environment including the influence of the trends of other wireless LAN terminals located in the vicinity (whether or not wireless communication is attempted at the same time). The interval time can also be set according to the contents. When the setting table 61 as shown in FIG. 9 is used, three reference values for determining each level according to the power intensity of the carrier and one CTS threshold (for classifying the number of CTS reception times) For example, it is necessary to store the number of times of 2 times as the threshold value in the memory 26.

  The setting table 62 of FIG. 10 shows an example of yet another setting table, and is used when the detection result of the C / N ratio and the number of receptions (count) of CTS are combined as determination conditions. For each level (good level, normal level, bad level) determined based on the C / N ratio detection result, the setting table 62 indicates whether the number of CTS receptions (count) is greater than or less than the CTS threshold. In addition, a numerical value for interval time is set for each association. Therefore, if the setting table 62 is used, the wireless LAN environment including the influence of surrounding noise generation and the trends of other wireless LAN terminals located in the surroundings (whether or not wireless communication is attempted at the same time, etc.) is included. The interval time can also be set according to the determined contents. When the setting table 62 as shown in FIG. 10 is used, three threshold values are used for determining each level according to the power intensity of the C / N ratio, and one threshold value is used for dividing the number of CTS reception times. Must be stored in the memory 26, respectively.

  A setting table 63 shown in FIG. 11 is an example of yet another setting table, and has a combination of three determination conditions: carrier power intensity, number of CTS receptions, and C / N ratio detection result. . The setting table 63 associates, for each level (good level, normal level, bad level) determined based on the power intensity of the carrier, whether the number of CTS receptions (count) is greater than or less than the CTS threshold, and further , The level determined based on the detection result of the C / N ratio (good level, normal level, bad level) is associated with each of the thresholds for CTS and above and below for the interval time for each combination based on the association The contents are set with numerical values. Therefore, by using the setting table 63, it is possible to determine the wireless LAN environment by generally judging the surrounding situation, and it is possible to set the interval time according to the determined content. When the setting table 63 as shown in FIG. 11 is used, three reference values for determining each level according to the power intensity of the carrier, one threshold for dividing the number of CTS reception times, and C / N In order to determine each level according to the power intensity of the ratio, it is necessary to store three reference values in the memory 26, respectively. 11 is basically the same as that of the setting table 40 shown in FIG. 4, and is equal to or more than the threshold value of the CTS count corresponding to each level based on the carrier strength. In each of the following cases, the normal level time based on the detection of the C / N ratio is the shortest, the good level time is the second shortest, and the bad level time is the longest.

  Further, the graph of FIG. 12 shows a modification example in which the wireless LAN environment in intermittent carrier sense may be performed every predetermined number of carrier senses without being performed every time. That is, the graph of FIG. 12 shows a case where the level determination process of the wireless LAN environment is performed at a rate of one out of two carrier senses. Specifically, the wireless LAN environment is determined to be “normal level” based on the comparison result between the detected carrier power intensity and the first reference value 34a in the time period (time 0 to t30) when the first carrier sense is performed. Thereafter, the interval time (time t30 to t31, t32 to t33) between the two subsequent carrier sense time zones is changed to 5 seconds corresponding to the “normal level”. In this case, the wireless LAN module 20 does not perform the comparison process between the detected carrier power intensity and the first reference value 34a in the time zone (time t31 to t32) in which the second carrier sense is performed.

  The wireless LAN environment is determined to be “good level” based on the comparison result between the detected carrier power intensity and the first reference value 34a in the third carrier sense time period (time t33 to t34). The interval time (time t34 to t35, t36 to t37) between the two subsequent carrier sense time zones is changed to 10 seconds corresponding to the “good level”.

  In this manner, in the processing pattern shown in the graph of FIG. 12, the level determination process of the wireless LAN environment is performed every two carrier sense time zones, so that the time of one carrier sense as shown in the graph of FIG. The processing load on the CPU 27 can be reduced as compared with the case where the level determination process is performed for each band. In addition, it is preferable to reduce the processing load of the CPU 27 by reducing the frequency of the wireless LAN environment level determination process as the fluctuation of the wireless LAN environment is small. Of course, it is also possible to apply the determination processing. In addition, in order to perform the level determination process every predetermined number of times as described above, the CPU 27 counts the number of times of the carrier sense period related to the ratio of performing the level determination process, and the number of the carrier sense that has reached the set ratio is counted. Level determination processing is performed during the time zone.

  FIG. 13 shows a wireless LAN module 50 which is a hardware modification. The wireless LAN module 50 according to the modified example has a configuration in which the processing part of the MAC layer 30 performed by software of the CPU 27 in FIG. 2 is replaced with a hardware circuit. Specifically, the wireless LAN module 50 includes various hardware functions corresponding to the upper MAC 31 and the lower MAC 32 including the CTS number detection block 31a and the carrier number detection block 31b that function as software, the Lower MAC 32, and the RF circuit unit 21 illustrated in FIG. Each of the circuits 51 to 54 is provided, and the wireless LAN module 50 is provided with a circuit control unit 55 for controlling the circuits 51 to 54 and a connection interface 57 with the main module 11.

  The RF circuit 51 is a circuit that performs processing corresponding to the RF circuit unit 21 in FIG. 1. The RF circuit 51 performs processing for detecting the power strength of the carrier related to the access point, and processing for detecting the C / N ratio. The C / N detection part 51b to perform is included. The access control circuit 52 is a portion corresponding to the Lower MAC 32 and the portion excluding the blocks 31a and 31b of the Upper MAC 31 of FIG. The CTS number detection circuit 53 is a circuit that performs processing corresponding to the CTS number detection block 31a in FIG. 2, and the carrier number detection circuit 54 is a circuit that performs processing corresponding to the carrier number detection block 31b in FIG. is there. In the wireless LAN module 50 of this modification, the RF circuit 51, the access control circuit 52, the CTS number detection circuit 53, and the carrier number detection circuit 54 are used as a processing part (access control means) that performs access control related to wireless communication. Equivalent to.

  Further, the circuit control unit 55 has an internal memory 56, and the internal memory 56 stores programs, menu data, reference value data, setting tables, display data, and the like. Based on the program stored in the internal memory 56, the circuit control unit 55 makes an access with unstable access status from a plurality of accessible access points as shown in the first and second flowcharts of FIGS. Processing for excluding points, processing for changing the interval time based on the level of the wireless LAN environment as shown in the graph of FIG. 6, and the like are performed.

  Note that the processes of the various modifications described above can also be applied to the wireless LAN module 50 of FIG. In addition, when simplifying the specifications of the wireless LAN modules 20 and 50, the stop processing of the processing portion related to access control in the intermittent carrier sense interval time may be omitted.

  The wireless communication device according to the present invention is not limited to being incorporated in the portable music player 10 in the form of wireless LAN modules 20 and 50 as shown in FIGS. The present invention can also be applied to information processing apparatuses such as PDAs and television devices, and various devices such as mobile phones and portable image display devices. In addition, the wireless communication device of the present invention may be configured as an independent wireless communication device in addition to being incorporated in various devices. For example, it may be configured in a card shape corresponding to various connection standards (PCMCIA standard, CF card standard, USB standard, IEEE 1394, etc.) and connectable to various information processing apparatuses. Furthermore, the wireless communication targeted by the wireless communication apparatus of the present invention is not limited to a wireless LAN, and various wireless devices such as Wireless USB and UWB (Ultra Wide Band) can be used as long as they perform intermittent carrier sensing. It can also be applied to communication.

It is a block diagram which shows the main internal structures of the portable music reproducing apparatus incorporating the wireless LAN module which concerns on embodiment of this invention. It is the figure which represented notionally the content which CPU functions as a MAC layer. It is the schematic of the access point list screen which shows the access point whose access condition is stable. It is a chart which shows the setting table of embodiment. It is the 1st flowchart which showed the processing procedure which excludes the access point with the unstable access condition at the time of carrier sense. It is a graph which shows the change of the interval time in intermittent carrier sense, the operating condition, and the state of power consumption. 10 is a second flowchart showing a processing procedure related to switching connection to another access point when the access point of the connection destination of the wireless LAN is unstable. It is a chart which shows the setting table of a modification. It is a chart which shows the setting table of another modification. It is a graph which shows the setting table of another modification. It is a graph which shows the setting table of another modification. It is a graph which shows the condition which performs the level determination of a wireless LAN environment at a rate of once in two carrier senses. It is a block diagram which shows the main internal structures of the wireless LAN module which concerns on a modification. It is the schematic which shows the condition which can access a some access point. It is the schematic which shows the list screen of the access point which can be accessed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Portable music player 20 Wireless LAN module 21 RF circuit part 22 Strength detection circuit 23 C / N detection circuit 25 MAC processing part 26 Memory 27 CPU
30 MAC layer 31 UpperMAC
31a CTS count detection block 31b Carrier count detection block 32 LowerMAC
34 reference value data 34a first reference value 34b second reference value 34c third reference value 36 access point list screen 40, 60, 61, 62, 63 setting table P program

Claims (6)

In a wireless communication device that performs wireless communication by accessing a wireless communication repeater,
Detection means for detecting an accessible wireless communication repeater;
When the detecting means detects a plurality of wireless communication repeaters, comparing means for comparing the access sensitivity of each wireless communication repeater with a reference level;
Identifying means for identifying whether there is a wireless communication repeater with an access sensitivity not exceeding a reference level based on the comparison of the comparing means;
When the specifying means specifies that there is a wireless communication repeater with an access sensitivity not exceeding the reference level, an exclusion means for excluding the wireless communication repeater from an access target , and
The comparison means compares at least the number of reception preparation completion signals related to wireless communication with a reference level as access sensitivity related to a wireless communication repeater . A display unit;
And a means for performing processing for selectively displaying information indicating a wireless communication repeater having an access sensitivity exceeding the reference level on the display unit from among a plurality of wireless communication repeaters detected by the detection unit. The wireless communication device according to 1.   The wireless communication apparatus according to claim 1, wherein the detection unit detects an accessible wireless communication repeater when performing carrier sense. Selection accepting means for accepting selection of a wireless communication repeater to be accessed from wireless communication repeaters remaining from exclusion by the exclusion means;
The wireless communication apparatus according to claim 3, further comprising: carrier sense means for performing carrier sense on the wireless communication repeater for which the selection accepting means has accepted the selection. The carrier sense means includes means for performing intermittent carrier sense,
The wireless communication apparatus according to claim 4, further comprising a changing unit that changes an intermittent time related to intermittent carrier sensing performed by the carrier sensing unit according to an access sensitivity related to the wireless communication repeater. 6. The wireless communication apparatus according to claim 1, wherein the detection unit performs detection while establishing a connection with one wireless communication repeater.

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