JP2008042457A - Radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication apparatus which can reduce burden on a processor when receiving and processing management frames which are transmitted at regular short time intervals or on other occasions. <P>SOLUTION: The radio communication apparatus 10 includes a received frame analyzer 13 which analyzes a received frame and determines whether it is a data frame or a management frame for managing the wireless connection with the communication partner. The received frame analyzer 13 notifies the host CPU 7 for processing frames of the reception of the frame, and receives management frames at regular time intervals. A beacon frame comparator 20 compares a portion of the current management frame which has just been received by the received frame analyzer 13 and a portion of a management frame received immediately before the current management frame as portions to be compared. When these portions to be compared are the same, the received frame analyzer 13 does not notify the host CPU 7 of the reception of the management frame. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus that performs wireless communication such as a wireless LAN.

  There is a form in which wireless communication with other devices is realized by incorporating or mounting a wireless communication device in an information terminal such as a multifunction peripheral such as a copy, fax, or scanner, or a personal computer. This wireless communication apparatus communicates with other devices in conformity with a protocol for wireless communication, and specifically processes functions related to the physical layer, the data link layer, and the like. Further, the multifunction peripheral and the information terminal process various application programs as well as functions related to a layer higher than the data link layer.

  Functions related to higher layers processed by a multifunction peripheral or information terminal can be shared with a wireless or wired-independent protocol such as IP (Internet Protocol). The multifunction peripheral or information terminal can be a wireless communication device or a wired communication device. Some devices can support wireless and wired communications by incorporating or mounting.

  In addition, functions and application programs related to higher layers are processed by a CPU (Central Processing Unit) installed in a multifunction peripheral or an information terminal. The processing capacity of a CPU mounted on a multifunction peripheral or information terminal may be low in operating frequency, unlike a CPU mounted on a general personal computer. In this case, the CPU processes various application programs. The wireless communication device should process most of the functions conforming to the protocol for wireless communication.

  Also, if the multifunction device or information terminal is a movable terminal that is supplied with power from the charger, it is important not to consume the power of the multifunction device or information terminal. Do not configure the wireless communication device to apply For example, the following techniques are known as conventional techniques that do not impose a load on the CPUs of multifunction peripherals and information terminals.

In the case of a method in which terminal stations communicate with each other directly without using a base station in the network, as in a wireless LAN ad hoc mode, the terminal station must always perform IP packet relay processing. Since the IP packet relay process is performed via the host CPU of the terminal station, it is a heavy load on the host CPU. Therefore, the terminal station detects whether the received packet is a packet addressed to itself or a packet to be relayed, and if it is a packet to be relayed, the packet to be relayed without going through the host CPU is detected by a specific electric circuit. Processing reduces the load on the CPU (see, for example, Patent Document 1).
JP 2005-303896 A

  For example, a signal compliant with IEEE 802.11, which is a wireless LAN protocol, includes a beacon frame for managing a wireless connection, and this beacon frame is generally transmitted at intervals of 100 milliseconds. When a terminal such as that described in reference 1 receives a beacon frame at a short interval addressed to itself, there is a problem that a load is applied to the host CPU.

  In addition, a management frame for managing wireless connection such as a beacon frame is a signal necessary for wireless communication because similar signals exist not only in IEEE802.11 but also in WirelessUSB and other protocols.

  Therefore, the present invention provides a wireless communication apparatus that can reduce the load on a processing unit such as a host CPU when receiving and processing a management frame in which management frames are transmitted at regular short intervals. Objective.

A wireless communication device according to the present invention is configured to wirelessly receive a frame transmitted from a communication partner, and to analyze a frame received by the communication unit to manage a data frame or a wireless connection with the communication partner. A wireless communication device having a reception frame analysis unit that determines whether the frame is a management frame, wherein the reception frame analysis unit notifies the processing unit that processes the frame of reception of the frame, and receives the management frame at regular time intervals And a comparison unit for comparing a part of the current management frame received by the received frame analysis unit and the management frame received immediately before as a comparison target, and the comparison target is matched, The reception frame analysis unit does not notify the processing unit of reception of the management frame, and if the comparison object does not match, the reception frame analysis unit It has a configuration for notifying the reception of the management frame to the processing unit.
With this configuration, when the comparison targets match, the host does not notify the processing unit that the management frame has been received. The load on a processing unit such as a CPU can be reduced.

In the wireless communication apparatus of the present invention, the management frame is configured by a header part and a body part including time stamp information, and the comparison target is the time stamp among the information constituting the management frame. It has a configuration that is a part excluding information and the header part.
With this configuration, since the portion excluding the time stamp information and the header portion of the information constituting the management frame is a comparison target, an efficient comparison can be performed for the management frame.

In the wireless communication device of the present invention, the management frame includes a header portion and a body portion including a variable length or fixed length information element, and the comparison target is the variable length or fixed length information. It has a configuration that is an element.
With this configuration, since information elements included in the body part are to be compared, it is possible to determine whether only necessary information elements have been changed.

In the wireless communication apparatus of the present invention, the comparison target has a configuration that is a specific part of 1 bit or more in the variable length or fixed length information element.
With this configuration, since a specific portion of 1 bit or more among the information elements included in the body portion is to be compared, it is possible to confirm a change only in the necessary information portion.

In the wireless communication apparatus of the present invention, the comparison target has a configuration in which one or more of the variable length or fixed length information elements or the specific portion is the target.
With this configuration, it is possible to cope with a protocol change by simultaneously making a plurality of pieces of information to be compared without limiting the number of comparison targets to one.

The wireless communication device of the present invention further includes a frame number counter that counts the number of the management frames received by the received frame analysis unit, and periodically makes the processing unit refer to the number counted by the frame number counter. It has a configuration.
With this configuration, since the processing unit periodically refers to the number counted by the frame number counter, the processing unit can grasp the reception status of the management frame.

The wireless communication apparatus of the present invention further includes a time stamp information storage unit that stores the latest time stamp information of the management frame received by the received frame analysis unit, and the latest time stored by the time stamp information storage unit. The stamp information is periodically referred to by the processing unit.
With this configuration, since the latest time stamp information is periodically referred to by the processing unit, the processing unit can grasp the reception status of the management frame.

The wireless communication apparatus of the present invention further includes a timer processing unit that counts a predetermined time repeatedly, and the reception frame analysis unit receives the management frame immediately after the timer processing unit times the predetermined time. The management unit is notified of reception of the received management frame.
With this configuration, when a management frame is received immediately after measuring a certain time, the processing unit periodically refers to information related to the reception status of the management frame in order to notify the reception of the received management frame to the processing unit. It is not necessary to perform this operation, and the load on the processing unit can be reduced.

The wireless communication device of the present invention further includes a frame number counter that counts the number of the management frames received by the reception frame analysis unit, and the reception frame analysis unit is configured such that the number counted by the frame number counter is a predetermined value. In the case of the above, the number counted by the frame number counter is reset, and when the management frame is received immediately after the predetermined value or more is reached, the reception of the received management frame is notified to the processing unit. It has a configuration.
With this configuration, when a management frame is accepted immediately after the value exceeds a predetermined value, the processing unit periodically refers to information related to the reception status of the management frame in order to notify the reception of the received management frame to the processing unit. It is not necessary to perform such operations, and the load on the processing unit can be reduced.

  As described above, the present invention provides a wireless communication apparatus that can reduce the load on a processing unit such as a host CPU when receiving and processing a management frame in which management frames are transmitted at regular short intervals. This is a great effect when a low-performance CPU is used.

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

  FIG. 1 is an example of a configuration diagram of a communication system according to an embodiment of the present invention. The communication system shown in FIG. 1 is configured by a communication device 9 serving as an access point for communicating in the infrastructure mode, a wireless communication device 10 serving as a station, and a device 8 incorporating or mounting the wireless communication device 10. The

  The communication system shown in FIG. 1 performs wireless communication in accordance with the IEEE 802.11 protocol, but the present invention is not limited to the IEEE 802.11 protocol.

  The wireless communication device 10 communicates with the communication device 9 wirelessly, and specifically processes functions related to the physical layer and the data link layer. In addition, the device 8 has a processing unit such as a CPU having a low operating frequency, and the processing unit executes functions and application programs related to higher layers of the protocol. The device 8 represents a multifunction device, an information terminal, or the like.

  First, the communication device 9 and the wireless communication device 10 execute a procedure for establishing a wireless connection (data link) when performing wireless communication. After the wireless connection is established, data transmission / reception is performed between the communication device 9 and the wireless communication device 10. Note that data transmission / reception is not performed between the communication device 9 and the wireless communication device 10 in which wireless connection is not established. Further, after the wireless connection is established, a beacon frame for managing the wireless connection is broadcast from the communication device 9 to the wireless communication device 10 at a short interval of about 100 milliseconds.

  If the device 8 determines that it has not received a beacon frame for a certain period of time or more via the wireless communication device 10, it considers that the wireless connection has been disconnected. Further, the beacon frame includes information indicating whether or not the communication device 9 has data to be transferred to the wireless communication device 10. Details of the beacon frame will be described later.

(First embodiment of the present invention)
FIG. 2 is an example of a block diagram of the wireless communication apparatus according to the first embodiment of the present invention. In FIG. 2, only the minimum functional blocks necessary for explaining the contents of the present invention are clearly shown, and some functional blocks are omitted.

  The wireless communication apparatus 10 illustrated in FIG. 2 includes a physical layer that conforms to the IEEE 802.11 protocol, a physical layer unit (communication unit) that implements the functions of the MAC layer, and a MAC layer unit. Further, the host CPU 7 constitutes the device 8 described with reference to FIG.

  The physical layer unit receives a frame conforming to the IEEE 802.11 protocol from the MAC layer unit and performs modulation processing, and a radio wave obtained by modulating the frame modulated by the modulation / demodulation unit 11 into a high frequency from an antenna. The RF processing unit 12 is configured to emit. When receiving a radio wave having a specific frequency from the antenna, the RF processing unit 12 converts it to a baseband frequency, and the modulation / demodulation unit 11 demodulates the frame, and transfers the demodulated frame to the MAC layer unit.

  The MAC layer unit includes a reception frame analysis unit 13, a reception frame buffer 14, a transmission frame generation unit 15, a transmission frame buffer 16, a frame transmission / reception timing control unit 17, a physical layer control unit 18, a beacon frame storage unit 19, and a beacon frame body. The comparison unit 20 is used. For example, each unit configuring the MAC layer unit is configured by an electronic circuit or the like.

  The reception frame analysis unit 13 analyzes a frame transferred from the physical layer unit, and manages a data frame (hereinafter referred to as a data frame) or a management frame (hereinafter referred to as a management frame for managing a wireless connection with a communication partner). Is called a management frame). The received frame analysis unit 13 stores only frames to be transferred to the host CPU 7 such as frames addressed to the own station among frames transferred from the physical layer unit in the received frame buffer 14 and notifies the host CPU 7 of an interrupt. . Further, the reception frame analysis unit 13 may accumulate only the frames to be transferred to the host CPU 7 in the reception frame buffer 14 and cause the reception frame buffer 14 to notify the interrupt.

  Here, a format of a frame processed in the MAC layer unit will be described with reference to FIG. The frame shown in FIG. 3 includes a frame header part and a frame body part. The frame header portion includes a frame control (Frame Control) including information specifying the frame type, a duration (Duration) ID, an address (Address), and a sequence control (Sequence Control). The frame body part has a variable length and includes a variable length frame body (Frame Body) and a 32-bit FCS (Frame Check Sequence) for error detection.

  The frame control includes a type (Type) and a subtype (Subtype), and a combination of these allows 25 types of frames to be identified. Among the 25 types of frames, there are a data frame or a management frame such as a beacon, ACK, RTS, and CTS.

  FIG. 4 shows the format of the management frame. As shown in FIG. 4, the management frame includes information representing a BSSID (Basic Service Set Identifier). Since the access point MAC address is set in the BSSID, the received frame analysis unit 13 can determine whether the frame is from the connected access point.

  When the data frame is transferred from the physical layer unit, the received frame analysis unit 13 notifies the host CPU 7 of an interrupt in order to cause the host CPU 7 to process the data frame, and the management frame is transferred from the physical layer unit. In this case, an interrupt notification is sent to the host CPU 7 in order to cause the host CPU 7 to process the management frame. The reason for processing the management frame by the host CPU 7 is that if the management frame is processed by an electronic circuit in the MAC layer portion, this electronic circuit will be replaced when the protocol is changed or added. If the management frame is processed in, the program can be changed, and the change or addition of the protocol can be flexibly handled.

  The transmission frame generation unit 15 generates a frame (ACK frame) that responds to the received management frame in order to perform processing conforming to the IEEE 802.11 protocol. The transmission frame generation unit 15 is configured to accumulate the generated frames in the transmission frame buffer 16. Note that the transmission frame buffer 16 accumulates the frames transferred from the host CPU 7 in addition to the frames generated by the transmission frame generation unit 15.

  The frame transmission / reception timing control unit 17 is for measuring frame transmission / reception timing in order to prevent a collision between a frame that the wireless communication apparatus 10 is about to transmit and a frame transmitted by another wireless communication apparatus 10. The physical layer control unit 18 activates the physical layer unit in response to an instruction from the frame transmission / reception timing control unit 17 so that the frames accumulated in the transmission frame buffer 16 are transmitted wirelessly.

  Also, the received frame analysis unit 13 causes the beacon frame storage unit 19 to store only the beacon frames addressed to the own station among the management frames transferred from the physical layer unit. The beacon frame body comparison unit 20 compares the beacon frame currently received by the reception frame analysis unit 13 with the body part of the beacon frame received immediately before.

  For the beacon frame, the frame type in the frame control information of the management frame shown in FIG. 4 represents the beacon frame, and the frame body part of the management frame represents the transmission time of the beacon frame as shown in FIG. It includes information such as a time stamp (Time Stamp), a beacon interval indicating a beacon frame interval (Beacon interval), and a traffic information map (TIM: Traffic Information Map) indicating presence / absence of data addressed to the own station.

  Although the information shown in FIG. 5 is used when establishing a wireless connection, it is not always referred to by the host CPU 7 after the wireless connection is established. In addition, the information representing the time stamp is updated every time transmission is performed, and the information representing the TIM changes depending on the presence / absence of data addressed to the own station. However, after the wireless connection is established, information other than the time stamp and the TIM Information hardly changes.

  In the wireless communication device 10 configured as described above, an operation when a beacon frame is received will be described below.

  First, the received frame analysis unit 13 analyzes the frame received from the physical layer unit, and if it is a beacon frame addressed to the own station, the beacon frame body comparison unit 20 uses the beacon frame currently received by the received frame analysis unit 13. And the body part stored in the beacon frame storage unit 19 and the beacon frame received immediately before are compared. When the beacon frame body comparison unit 20 compares the body parts of the beacon frames, the beacon frames of the parts excluding information indicating the time stamp are compared.

  When the body part of the beacon frame in the portion excluding the information indicating the time stamp does not match, the reception frame analysis unit 13 accumulates the currently accepted beacon frame in the reception frame buffer 14 and notifies the host CPU 7 of an interrupt. If they match, the received frame buffer 14 is not accumulated and no interrupt notification is given.

  Finally, after comparing the beacon frames, the reception frame analysis unit 13 stores the currently accepted beacon frames in the beacon frame storage unit 19.

  As described above, the first embodiment of the present invention has been described. In the conventional wireless communication apparatus, when a beacon frame transmitted at a short interval of about 100 milliseconds is received every time, the host CPU 7 is frequently interrupted. Therefore, the host CPU 7 has been loaded, but in the wireless communication apparatus according to the first embodiment of the present invention, if the beacon frame of the portion excluding the information indicating the time stamp does not change, the host CPU 7 Since no interruption is performed on the host CPU 7, the load on the host CPU 7 is reduced.

  Further, in the first embodiment of the present invention, the body part of the beacon frame of the part excluding the information indicating the time stamp is set as the comparison object, but the beacon frame body comparison unit 20 is replaced with the information comparison unit 21. The configuration shown in FIG.

  In order to prevent the host CPU 7 from accepting an interrupt notification even when information that is not referred to by the host CPU 7 other than information indicating TimeStamp is updated, the information comparison unit 21 designates and compares comparison targets for each specific information. It has become.

  For example, the information comparison unit 21 can set the capability information (Capability Information) shown in FIG. 5 as the comparison target, and can determine whether or not the capability information has changed. Further, as shown in FIG. It is also possible to determine whether there is a change in any information among the information constituting the information.

  In the capability information in FIG. 7A, five pieces of information having a 1-bit length are allocated, but it is possible that the capability information will further increase in the future due to protocol changes. The information comparison unit 21 performs bit masking of each information, narrows down the target bits in the mask pattern, and sets only the narrowed down bits as comparison targets so as to be able to cope with the update of information allocated in bit units. It can be compared with the information in the frame body part of the immediately preceding beacon frame. As a specific example, the information comparison unit 21 can also determine whether or not there is a change in the ESS and privacy information illustrated in FIG.

  The information comparison unit 21 can compare not only fixed-length information elements in the frame body portion of the received beacon frame but also variable-length information elements called elements. FIG. 7B shows an image having a plurality of variable length information elements in the frame body portion of the beacon frame. The information comparison unit 21 can also compare a specific part of a variable length information element or a variable length information element.

  Note that the information comparison unit 21 can compare a 1-bit specific part and a specific part of 1 or more bits among variable-length or fixed-length information elements as shown in FIG. Alternatively, the entire fixed-length information element or one or more specific parts of variable-length or fixed-length information elements can be combined for comparison.

  By the way, the beacon frame is also used for determining whether or not the wireless connection with the access point is disconnected. In the first embodiment of the present invention, if there is no change in specific information in the frame body part of the currently accepted beacon frame and the beacon frame received immediately before, no interruption to the host CPU 7 is performed. Therefore, if the host CPU 7 does not notify the host CPU 7 that the beacon frame has been received, the host CPU 7 may determine that the radio wave has not been received from the access point and the host CPU 7 has been disconnected. It is necessary to recognize that the beacon frame has been accepted. Therefore, in the second and subsequent embodiments of the present invention, a method for recognizing that the host CPU 7 regularly receives beacon frames will be described.

(Second embodiment of the present invention)
FIG. 8 is an example of a block diagram of a wireless communication apparatus according to the second embodiment of the present invention. Of the constituent members constituting the wireless communication apparatus according to the second embodiment of the present invention, the same constituent members as those described in the first embodiment of the present invention are denoted by the same reference numerals, Each description is omitted.

  The wireless communication device 22 illustrated in FIG. 8 includes a physical layer that conforms to the IEEE 802.11 protocol, a physical layer unit that implements the functions of the MAC layer, and a MAC layer unit.

  The MAC layer unit includes a reception frame analysis unit 23, a reception frame buffer 14, a transmission frame generation unit 15, a transmission frame buffer 16, a frame transmission / reception timing control unit 17, a physical layer control unit 18, a beacon frame storage unit 19, and an information comparison unit 21. , And a beacon frame number counter 24 composed of a register or the like.

  The reception frame analysis unit 23 has the same function as the reception frame analysis unit 13 and further increases the count number of the beacon frame number counter 24 by 1 when a beacon frame addressed to the own station is received. Accordingly, the beacon frame number counter 24 registers the number of times the beacon frame is received.

  On the other hand, the host CPU 7 can determine that it regularly accepts beacon frames by referring to the beacon frame number counter 24 at regular intervals and confirming that the number greater than a certain value has increased.

  Further, in the second embodiment of the present invention, the number of times a beacon frame is received is counted. However, the beacon frame number counter 24 is replaced with a time stamp information storage unit 25 configured by a register or the like in FIG. It can also be set as the structure shown.

  When receiving the beacon frame, the reception frame analysis unit 23 causes the time stamp information storage unit 25 to store the time stamp information of the beacon frame. The time stamp information storage unit 25 stores the latest time stamp information when a beacon frame is received. The host CPU 7 periodically accepts beacon frames by confirming that the time indicated by the latest time stamp information has increased by a predetermined value or more by referring to the time stamp information storage unit 25 at regular time intervals. It can be judged.

  For example, the host CPU 7 can refer to the beacon frame number counter 24 or the time stamp information storage unit 25 at regular intervals, and can determine that it has been disconnected if the registered value has not changed at all. . The host CPU 7 can also determine that the radio wave condition is bad when the difference between the previously registered value and the previously registered value is less than a certain value. Therefore, the host CPU 7 can grasp the reception status of the beacon frame.

  By the way, in the second embodiment of the present invention, the host CPU 7 can determine the beacon reception state by accessing a member constituted by a register or the like at regular intervals. In some cases, the host CPU 7 should not operate at regular intervals. Therefore, in the third and subsequent embodiments of the present invention, a method in which the host CPU 7 does not operate at regular intervals will be described.

(Third embodiment of the present invention)
FIG. 10 is an example of a block diagram of a wireless communication apparatus according to the third embodiment of the present invention. Of the constituent members constituting the wireless communication apparatus according to the third embodiment of the present invention, the same members as those described in the first embodiment of the present invention are denoted by the same reference numerals. Each description is omitted.

  The wireless communication device 30 illustrated in FIG. 10 includes a physical layer that conforms to the IEEE 802.11 protocol, a physical layer unit that implements the functions of the MAC layer, and a MAC layer unit.

  The MAC layer unit includes a reception frame analysis unit 33, a reception frame buffer 14, a transmission frame generation unit 15, a transmission frame buffer 16, a frame transmission / reception timing control unit 17, a physical layer control unit 18, a beacon frame storage unit 19, and an information comparison unit 21. And the timer processing unit 31.

  The timer processing unit 31 has a time setting register for registering a number representing a certain time, and a timer counter for adding 1 to a value held every clock cycle time. As shown in FIG. 11, with reference to a graph showing the relationship between the value of the timer counter and the time, the timer processing unit 31 determines the value of the timer counter, the value of the time setting register for each clock cycle time, Are compared for each clock cycle time, and if the respective values are the same, the reception frame analysis unit 33 is notified and the value of the timer counter is set to zero.

  The reception frame analysis unit 33 has the same function as the reception frame analysis unit 13, and when receiving a beacon frame addressed to itself immediately after receiving a notification from the timer processing unit 31, as shown in FIG. Without comparing the beacon frames by the information comparison unit 21 or the beacon frame body comparison unit 20, the beacon frames addressed to the own station are accumulated in the reception frame buffer 14, and the host CPU 7 is notified of an interrupt.

  In addition, when a beacon frame addressed to the own station is received in a situation where no notification is received from the timer processing unit 31, a part of the beacon frame does not match by the information comparison unit 21 or the beacon frame body comparison unit 20. May be represented. In this case, the reception frame analysis unit 33 may set the value of the timer counter to 0 in order to notify the host CPU 7 of an interrupt.

  As described above, when the wireless communication apparatus according to the third embodiment of the present invention receives a beacon frame immediately after measuring a certain time, it notifies the host CPU 7 of reception of the received beacon frame. It is not necessary for the host CPU 7 to periodically perform operations such as referring to and monitoring information related to the reception status of beacon frames, and the load on the host CPU 7 can be reduced.

(Fourth embodiment of the present invention)
FIG. 12 is an example of a block diagram of a wireless communication apparatus according to the fourth embodiment of the present invention. Of the constituent members constituting the wireless communication apparatus according to the fourth embodiment of the present invention, the same members as those described in the first embodiment of the present invention are denoted by the same reference numerals, Each description is omitted.

  The wireless communication device 40 shown in FIG. 12 includes a physical layer that conforms to the IEEE 802.11 protocol, a physical layer unit that implements the functions of the MAC layer, and a MAC layer unit.

  The MAC layer unit includes a reception frame analysis unit 43, a reception frame buffer 14, a transmission frame generation unit 15, a transmission frame buffer 16, a frame transmission / reception timing control unit 17, a physical layer control unit 18, a beacon frame storage unit 19, and an information comparison unit 21. , And a beacon frame number counter 41.

  The reception frame analysis unit 43 has the same function as the reception frame analysis unit 13. Furthermore, when the beacon frame addressed to the own station is received, if the information comparison unit 21 or the beacon frame body comparison unit 20 indicates that a part of the beacon frame matches, the reception frame analysis unit 43 The count number of the beacon frame number counter 41 is increased by one. Therefore, the beacon frame number counter 41 registers the number of times the beacon frame addressed to the own station is received and the host CPU 7 is not interrupted.

  If the count number of the beacon frame number counter 41 is equal to or greater than a register value (predetermined value) set in advance by the host CPU 7 or the like, the reception frame analysis unit 43 performs a beacon by the information comparison unit 21 or the beacon frame body comparison unit 20. Without comparing the frames, beacon frames addressed to the local station are accumulated in the reception frame buffer 14 and an interrupt notification is sent to the host CPU 7. The count number of the beacon frame number counter 41 is reset to zero. Although the reset value is 0, it is not limited to 0.

  When receiving a beacon frame addressed to the own station, if the comparison result by the information comparison unit 21 or the beacon frame body comparison unit 20 indicates that it does not match the beacon frame received immediately before, the received frame analysis unit 43 Resets the count number of the beacon frame number counter 41 to zero.

  As described above, when the wireless communication apparatus according to the fourth embodiment of the present invention receives a beacon frame immediately after reaching a predetermined value or more, it notifies the host CPU 7 of reception of the received beacon frame. It is not necessary for the host CPU 7 to periodically perform operations such as referring to and monitoring information related to the reception status of beacon frames, and the load on the host CPU 7 can be reduced.

  In the embodiment of the present invention, the communication system is described as the infrastructure mode. However, in the present invention, the communication system may be implemented in the ad hoc mode.

Configuration diagram of a communication system according to an embodiment of the present invention 1 is a block diagram of a wireless communication apparatus according to a first embodiment of the present invention. The figure showing the format of the frame processed by the MAC layer part Diagram showing management frame format The figure showing the information of the frame body part of the beacon frame The figure showing the other example of the 1st Embodiment of this invention The figure for explaining the example of the information when the information comparison section compares The block diagram of the radio | wireless communication apparatus which concerns on the 2nd Embodiment of this invention The figure showing the other example of the 1st Embodiment of this invention The block diagram of the radio | wireless communication apparatus which concerns on the 3rd Embodiment of this invention Graph of the relationship between timer counter value and time The block diagram of the radio | wireless communication apparatus which concerns on the 4th Embodiment of this invention

Explanation of symbols

7 Host CPU
8 device 9 communication device 10, 22, 30, 40 wireless communication device 11 modulation demodulation unit 12 RF processing unit 13, 23, 33, 43 reception frame analysis unit 14 reception frame buffer 15 transmission frame generation unit 16 transmission frame buffer 17 frame transmission / reception Timing control unit 18 Physical layer control unit 19 Beacon frame storage unit 20 Beacon frame body comparison unit (comparison unit)
21 Information comparison part (comparison part)
24, 41 Beacon frame counter (frame counter)
25 Time stamp information storage unit 31 Timer processing unit

Claims (9)

A communication unit that wirelessly receives a frame transmitted from a communication partner;
A reception frame analysis unit that analyzes a frame received by the communication unit and determines whether it is a data frame or a management frame for managing a wireless connection with the communication partner;
The received frame analysis unit is a wireless communication device that notifies the reception of the frame to a processing unit that processes the frame and receives the management frame at regular time intervals,
A comparison unit for comparing a part of the management frame received by the reception frame analysis unit and the management frame received immediately before as a comparison target;
When the comparison object is matched, the reception frame analysis unit does not notify the processing unit of reception of the management frame, and when the comparison object is not matched, the reception frame analysis unit is the processing unit A wireless communication apparatus that notifies the reception of the management frame to The management frame is composed of a header part and a body part including time stamp information,
The wireless communication apparatus according to claim 1, wherein the comparison target is a portion excluding the time stamp information and the header portion of information constituting the management frame. The management frame is composed of a header part and a body part including a variable length or fixed length information element,
The wireless communication apparatus according to claim 1, wherein the comparison target is the variable length or fixed length information element.   The wireless communication apparatus according to claim 3, wherein the comparison target is a specific part of one or more bits in the variable length or fixed length information element.   The wireless communication apparatus according to claim 4, wherein the comparison target is a combination of one or more of the variable length or fixed length information elements or the specific portion. A frame number counter that counts the number of the management frames received by the received frame analysis unit;
The wireless communication apparatus according to claim 1, wherein the processing unit periodically refers to the number counted by the frame number counter. A time stamp information storage unit that stores the latest time stamp information of the management frame received by the received frame analysis unit;
The wireless communication apparatus according to claim 1, wherein the latest time stamp information stored by the time stamp information storage unit is periodically referred to by the processing unit. It has a timer processing unit that counts time repeatedly,
2. The received frame analysis unit, when receiving the management frame immediately after the timer processing unit times the predetermined time, notifies the processing unit of reception of the received management frame. A wireless communication device according to any one of claims 1 to 5. A frame number counter that counts the number of the management frames received by the received frame analysis unit;
The received frame analysis unit resets the number counted by the frame number counter when the number counted by the frame number counter exceeds a predetermined value, and immediately after the count exceeds the predetermined value, 6. The wireless communication apparatus according to claim 1, wherein when the management frame is received, reception of the received management frame is notified to the processing unit.

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