JP5422766B2 - Wireless communication apparatus and wireless communication method - Google Patents

Description

  Embodiments relate to wireless communication.

  For example, IEEE 802.11 is known as a wireless communication system based on carrier sense. In IEEE 802.11, the carrier sense level is uniquely determined for each physical method. Therefore, according to IEEE 802.11, a plurality of wireless communication apparatuses using the same physical method can share the same wireless medium and coexist.

  However, a wireless communication device (referred to as a first wireless communication device for convenience in the description of the background art) is based on a wireless communication method (wireless communication method based on carrier sense) such as IEEE 802.11, for example. There may be a problem when close proximity wireless communication in which the communication range is limited to, for example, several centimeters by controlling the maximum transmission power. Specifically, another wireless communication device that uses a normal maximum transmission power (referred to as a second wireless communication device for convenience in the description of the background art) is the same as the first wireless communication device. When a wireless medium is used and the first wireless communication device is within the communication range of the second wireless communication device, it is difficult for both to coexist. For example, the transmission signal from the first wireless communication device does not reach the carrier sense level of the second wireless communication device, but the transmission signal from the second wireless communication device reaches the carrier sense level of the first wireless communication device. Reach. Therefore, the second wireless communication apparatus can transmit a signal regardless of the transmission state from the first wireless communication apparatus, but the first wireless communication apparatus transmits a signal depending on the transmission state from the second wireless communication apparatus. Is disturbed. That is, the first wireless communication device is inferior to the second wireless communication device.

  In addition, the conventional wireless communication scheme based on carrier sense assumes communication between a plurality of wireless communication devices. Furthermore, this wireless communication system is designed based on a policy for maintaining the communication link even if it deteriorates. On the other hand, in close proximity wireless communication, communication between a plurality of wireless communication devices is not necessarily emphasized, and it is often sufficient that one-to-one communication can be realized. Furthermore, as the required specifications for close proximity wireless communication, it is possible to shorten the time until the start of data exchange, or to disconnect the communication link when the communication distance becomes long.

IEEE P802.11-2007

  An embodiment aims to realize a proximity wireless communication system in view of a wireless communication system based on a conventional carrier sense.

  According to the embodiment, the wireless communication device includes a first wireless communication method and a second wireless communication that are required to determine that the wireless medium is busy when the reception level is equal to or higher than the minimum reception sensitivity of the physical method. Among the methods, at least the second wireless communication method is supported. The wireless communication device includes a first processing unit, a second processing unit, and a third processing unit. When the second wireless communication scheme is used, the first processing unit sets a value lower than the maximum transmission power of the first wireless communication scheme as the maximum transmission power of the second wireless communication scheme, and physically A value higher than the minimum receiving sensitivity of the system is set as the carrier sense level. The second processing unit performs carrier sense using the carrier sense level. The third processing unit controls transmission / reception of signals via the second processing unit.

1 is a block diagram illustrating a wireless communication device according to a first embodiment. Explanatory drawing of the carrier sense level which a proximity type radio | wireless communication apparatus uses. The block diagram which illustrates the radio communications equipment concerning a 2nd embodiment. FIG. 6 is a block diagram illustrating a wireless communication apparatus according to a third embodiment. Explanatory drawing of the schedule of Beacon Interval. MLME-SCAN. The table which illustrates the parameter with which a request primitive is provided.

  Hereinafter, embodiments will be described with reference to the drawings. In each embodiment, the same or similar elements as those already described are denoted by the same or similar reference numerals, and redundant description is basically omitted.

  In the following description of each embodiment, an IEEE 802.11 wireless LAN is assumed as an example of a wireless communication system based on carrier sense. Of course, each embodiment can be appropriately applied to other wireless communication systems.

  IEEE 802.11 handles multiple frequency bands. IEEE 802.11 provides a physical (PHY) layer definition for each of these frequency bands. The medium access control (MAC) layer is defined above the PHY rule.

  For example, 802.11a defines the 5 GHz band, 802.11g defines the 2.4 GHz band, and 802.11n defines the 2.4 GHz band and the 5 GHz band. Further, 802.11ad that is being formulated will specify the 60 GHz band (millimeter wave band).

  Each of these PHY rules includes a carrier sense level rule. The wireless communication device needs to determine that the medium (Clear Channel Assessment) is busy when it receives electric power that exceeds the specified carrier sense level. More specifically, when a wireless communication apparatus receives a PHY signal corresponding to the wireless communication apparatus, if the reception level (Receive Signal Strength Indicator; RSSI) is equal to or higher than the minimum reception sensitivity of the PHY system, the wireless communication apparatus It is necessary to determine that the medium (CCA) is busy. Otherwise (for example, when a signal that is unknown as to whether the corresponding PHY system is received, when a signal with a PHY system different from the corresponding PHY system is received, or when only noise is received), the reception level thereof Is equal to or greater than a value obtained by adding a fixed value to the minimum reception sensitivity, the wireless communication apparatus needs to determine that the medium (CCA) is busy. In the IEEE802.11 wireless LAN, this fixed value is basically set to 20 dB. In the following description, reference is made to the adjustment of the carrier sense level. This carrier sense level refers to the carrier sense level when a corresponding PHY system signal is received (that is, a fixed value is not added).

  Here, the detection method of the PHY method will be briefly described. In the PHY header of the PHY packet, the PHY method used for transmitting the PHY packet is described. Therefore, if the received signal is a PHY packet, the wireless communication apparatus can determine whether or not a corresponding PHY signal has been received by referring to the PHY header.

(First embodiment)
As illustrated in FIG. 1, the wireless communication apparatus according to the first embodiment includes a host processing unit 100, a MAC processing unit 10, a PHY processing unit 40, a frequency conversion circuit 50, and an antenna 60.

  The upper processing unit 100 performs processing for the upper layer on the MAC layer. The host processing unit 100 can exchange signals with the MAC processing unit 10.

  The MAC processing unit 10 performs processing for the MAC layer. As described above, the MAC processing unit 10 can exchange signals with the host processing unit 100. Further, the MAC processing unit 10 can exchange signals with the PHY processing unit 40. The MAC processing unit 10 includes a reception processing unit 20 and a transmission processing unit 30.

  The PHY processing unit 40 performs processing for the PHY layer. As described above, the PHY processing unit 40 can exchange signals with the MAC processing unit 10. The PHY processing unit 40 is connected to the antenna 60 via the frequency conversion circuit 50. The frequency conversion circuit 50 performs up-conversion / down-conversion for signal transmission / reception.

  In addition, although the antenna 60 is shown as if it was one in FIG. 1 or another drawing, it is needless to say that there may be a plurality of antennas. A plurality of different PHY processing units 40 may be provided. When a plurality of PHY method processing units 40 are provided, a reception processing unit 20 and a transmission processing unit 30 corresponding to each of them may be provided. Furthermore, a common processing unit that straddles a plurality of PHY processing units 40 may be provided.

  Moreover, the radio | wireless communication apparatus which concerns on this embodiment can suppress the mounting area of this antenna 60 small by including (integrating) the antenna 60 as a component as FIG. 1 shows. Furthermore, in the wireless communication apparatus according to the present embodiment, the reception processing unit 20 and the transmission processing unit 30 share the antenna 60, as shown in FIG. Since the reception processing unit 20 and the transmission processing unit 30 share the antenna 60, the wireless communication apparatus of FIG. 1 can be mounted in a small size. Of course, the wireless communication apparatus according to the present embodiment may have a configuration different from that illustrated in FIG.

  At the time of signal transmission, the PHY processing unit 40 receives a MAC frame from the transmission processing unit 30. The PHY processing unit 40 performs processing such as encoding on the MAC frame to convert it into a PHY packet. The frequency conversion circuit 50 converts the PHY packet into a radio signal in a necessary frequency band (for example, a millimeter wave band of 60 GHz). The antenna 60 radiates a frequency-converted radio signal. The PHY processing unit 40 outputs a signal indicating that the medium is busy to the MAC processing unit 10 (more precisely, the reception processing unit 20) during the signal transmission period.

  When receiving the signal, the frequency conversion circuit 50 converts the radio signal received by the antenna 60 into a signal in a necessary frequency band (baseband that can be processed by the PHY processing unit 40). The PHY processing unit 40 receives a baseband reception signal, detects the reception level, and determines the PHY method. The PHY processing unit 40 selects a carrier sense level according to the PHY method and compares it with the reception level. If the reception level is equal to or higher than the selected carrier sense level, the PHY processing unit 40 outputs a signal indicating that the medium (CCA) is busy to the MAC processing unit 10 (more precisely, the reception processing unit 20). . Otherwise, the PHY processing unit 40 outputs a signal indicating that the medium (CCA) is idle to the MAC processing unit 10 (more precisely, the reception processing unit 20). If the PHY method of the received signal is appropriate (that is, the wireless communication device is compatible), the PHY processing unit 40 performs a decoding process, a process of removing the preamble and the PHY header, and the like to extract the payload. The PHY processing unit 40 passes the payload to the reception processing unit 20 as a MAC frame. Furthermore, the PHY processing unit 40 notifies the reception processing unit 20 of the reception start of the PHY packet before passing the MAC frame to the reception processing unit 20, and ends the reception of the PHY packet after passing the MAC frame to the reception processing unit 20. Notify the reception processing unit 20. In addition, if the received PHY packet is normal (if no error is detected), the PHY processing unit 40 notifies the end of reception of the PHY packet and receives a signal indicating that the medium is idle. To pass. Even when an error is detected in the received packet, the PHY processing unit 40 notifies the reception processing unit 20 that an error has been detected.

  The MAC processing unit 10 handles three types of MAC frames, a data frame, a control frame, and a management frame, and performs various processes defined in the MAC layer. Here, three types of MAC frames will be described.

  The management frame is used for management of communication links with other wireless communication devices. For example, a management frame is exchanged for authentication or for establishing a communication link, a Beacon frame that broadcasts group attributes and synchronization information to form a wireless communication group that is a Basic Service Set (BSS) in IEEE 802.11 Frame to be included.

  The data frame is used to transmit data to the other wireless communication device in a state where a communication link is established with the other wireless communication device. For example, data is generated in the wireless communication apparatus of FIG. 1 by a user's application operation, and the data is conveyed by a data frame. Specifically, the generated data is transferred from the higher-level processing unit 100 to the transmission processing unit 30, stored in the frame body field of the data frame as a payload, and transmitted. Also, when the reception processing unit 20 receives a data frame, the information of the frame body field is extracted and processed as data, and passed to the upper processing unit 100. As a result, application operations such as data writing and reproduction occur.

  The control frame is used for control when the management frame and the data frame are transmitted / received (exchanged) with another wireless communication apparatus. The control frame includes an RTS (Request to Send) frame, a CTS (Clear to Send) frame, etc. that are exchanged with other wireless communication devices in order to reserve a medium before starting the exchange of the management frame and the data frame. Include. In addition, the control frame includes an ACK (Acknowledgement) frame, a BA (Block Ack) frame, and the like transmitted for confirming delivery of the received management frame and data frame.

  The MAC processing unit 10 needs to acquire an access right (transmission right) on the medium before transmitting the MAC frame. The transmission processing unit 30 measures transmission timing based on carrier sense information (described later) from the reception processing unit 20. The transmission processing unit 30 gives a transmission instruction to the PHY method processing unit 40 according to the transmission timing and passes the MAC frame. In addition to the transmission instruction, the transmission processing unit 30 may instruct the modulation scheme and encoding scheme used for transmission together. In addition to these, the transmission processing unit 30 may instruct transmission power. Once the access right is acquired, the MAC processing unit 10 continuously exchanges MAC frames with other wireless communication devices, although there are restrictions such as the time that the medium can be occupied and QoS (Quality of Service) attributes. can do. The access right is acquired when the wireless communication apparatus transmits a predetermined frame and correctly receives a response frame from another wireless communication apparatus. When the predetermined frame is received by, for example, another wireless communication device, the other wireless communication device transmits the response frame after a minimum frame interval (Short InterFrame Space).

  The reception processing unit 20 manages carrier sense information. This carrier sense information includes carrier sense (physical carrier sense) information related to busy / idle of the medium (CCA) input from the PHY processing unit 40 and a virtual carrier based on the medium reservation time described in the received frame. It includes both sense (virtual carrier sense) information. If any one of the carrier sense information indicates busy, the medium is regarded as busy, and signal transmission during that time is prohibited. In IEEE 802.11, the medium reservation time is described in a so-called Duration / ID field in the MAC header. When the MAC processing unit 10 receives a MAC frame addressed to another wireless communication device (not addressed to itself), the medium is virtually busy for the medium reservation time from the end of the PHY packet including the MAC frame. Is determined. Such a mechanism for virtually determining that a medium is busy, or a period during which a medium is virtually busy is called a NAV (Network Allocation Vector).

  As will be described later, the wireless communication apparatus according to the present embodiment is based on a normal wireless communication system using carrier sense (CCA) according to the minimum reception sensitivity for the above-described PHY system, and the normal wireless communication system and Realize coexistence close proximity wireless communication system. In the following description, a normal wireless communication method is referred to as a normal method (or a non-proximity method) for convenience, and a close proximity wireless communication method that can coexist with the normal method is a proximity method for convenience. It is called.

  Note that the wireless communication apparatus according to the present embodiment may be compatible with only a specific frequency band system, or may be a hybrid apparatus compatible with a plurality of frequency band systems. Furthermore, the wireless communication apparatus according to the present embodiment may support both a proximity method and a normal method (for example, a wireless LAN). In the following description, it is assumed that the wireless communication apparatus according to the present embodiment supports at least a proximity method based on a normal wireless LAN method. Here, as the proximity method, a communication range is assumed to be limited to the order of several centimeters (for example, 3 cm), and communication is possible only within the communication range.

  The wireless communication device controls the maximum transmission power in order to limit the communication range. For example, when the wireless communication apparatus uses a millimeter wave band, it can be assumed that the propagation loss is free space propagation loss +10 dB and the antenna gain is 0 dB for both transmission and reception. Here, the wireless communication apparatus selects and transmits a basic management frame such as Beacon, for example, by selecting a predetermined modulation and coding scheme (Modulation and Coding Scheme; MCS) having the lowest reception sensitivity in the system. This MCS is MCS0, and its reception sensitivity is -78 dBm. On the other hand, the wireless communication apparatus selects and transmits other frames including data frames, etc., by selecting one of MCS1 to MCS12 having higher reception sensitivity than MCS0. Among these MCS1 to MCS12, the minimum reception sensitivity is assumed to be −68 dB of MCS1. In addition, MCS0 and MCS1 to MCS12 are distinguished as different PHY methods.

  For example, when the wireless communication apparatus selects MCS0, it is assumed that the transmission power needs to be −30 dBm in order to set the reception level at a position 3 centimeters away to −78 dBm. On the other hand, when the wireless communication apparatus selects MCS4, it is assumed that the transmission power needs to be -16 dBm in order to make the reception level at a position 3 cm away from the reception sensitivity -64 dBm (reception of MCS4 Since the sensitivity -64 dBm is 14 dB higher than the reception sensitivity -78 dBm of MCS0, it is necessary to increase the transmission power by 14 dB). When the transmission power is −16 dBm, the distance at which the carrier sense (CCA) is busy, that is, the distance at which the reception level exceeds the reception sensitivity −68 dBm of MCS1 is, for example, 5 cm. That is, the distance that the carrier sense (CCA) is busy is extended as compared with the case where the wireless communication apparatus selects MCS0. If there is a request for the lowest transmission speed in the predetermined communication range in the proximity wireless communication, the wireless communication apparatus selects one of the MCSs that can achieve the transmission speed, and at the end of the predetermined communication range. What is necessary is just to set the maximum transmission power so that it may become a receiving sensitivity. Then, the wireless communication apparatus can select only the MCS or the MCS having a higher transmission rate and perform transmission with transmission power equal to or less than the set maximum transmission power. That is, the maximum transmission power of the wireless communication device is reduced as compared with the normal method.

  By the way, the transmission power of the normal system is usually about 0 dBm to several tens of dBm. That is, the transmission power after the control is reduced by about several tens of dB as compared to the normal method, as illustrated for MCS0 and MCS1 to MCS4.

  Further, the method of limiting the communication range by controlling the maximum transmission power is inferior in coexistence with the normal method. For example, a wireless communication device that transmits a Beacon frame with a transmission power of 10 dBm (referred to as a second wireless communication device in the present embodiment for convenience), and transmits a Beacon frame with a maximum transmission power limited to −30 dBm. It is assumed that a wireless communication device (referred to as a first wireless communication device for convenience in the present embodiment) is disposed. When the second wireless communication apparatus selects MCS0 and transmits a Beacon frame with a transmission power of 10 dBm, the reception sensitivity at a position 3 m away is −78 dBm. Therefore, if the distance from the first wireless communication apparatus to the second wireless communication apparatus is within 3 m, the reception level in the first wireless communication apparatus is −78 dBm or more. That is, the first wireless communication apparatus determines that CCA is busy. On the other hand, when the first wireless communication apparatus selects MCS0 and transmits a Beacon frame at −30 dB, the reception sensitivity at a position 3 cm away is −78 dBm. Therefore, if the distance from the second wireless communication device to the first wireless communication device exceeds 3 cm, the reception level in the second wireless communication device is less than −78 dBm. That is, the second wireless communication apparatus determines that the CCA is idle. Therefore, while the second wireless communication device is transmitting a signal, the first wireless communication device detects interference and cannot transmit the signal. On the other hand, while the first wireless communication apparatus is transmitting a signal, the second wireless communication apparatus can transmit a signal because it does not detect interference. Therefore, the first wireless communication device is inferior because it is difficult to acquire the transmission right as compared to the second wireless communication device.

  Therefore, the wireless communication apparatus according to the present embodiment realizes the proximity method described below. This proximity method, for example, limits the maximum transmission power and uses a higher carrier sense level than the normal method. That is, the proximity wireless communication apparatus does not interfere with the normal wireless communication apparatus (the normal wireless communication apparatus does not determine that CCA is busy when the proximity wireless communication apparatus transmits a signal). In the case of being away from each other, interference is not detected even if a signal is received from a normal wireless communication apparatus. Specifically, the PHY processing unit 40 does not determine that the CCA is busy, and does not give such notification to the MAC processing unit 10 (more precisely, the reception processing unit 20). Note that the proximity method uses the same PHY method (the same PHY packet format and the same MCS set) as the normal method. Further, it is assumed that the proximity method is required to achieve the transmission speed of MCS0 at a position 3 cm away.

  Hereinafter, the carrier sense level used by the proximity wireless communication apparatus will be described with reference to FIG. The normal type wireless communication apparatus selects MCS0 at a transmission power of 10 dBm and transmits a signal, and the proximity type wireless communication apparatus transmits MCS0 at a transmission power of 0 dBm (that is, the maximum transmission power of the proximity type is limited to 0 dBm). Is selected and a signal is transmitted. Further, it is assumed that the propagation loss is free space propagation loss +10 dB and the antenna gain is 0 dB for both transmission and reception. In FIG. 2, the wireless communication apparatus is displayed as “STA (station)”. When the distance between the normal wireless communication device and the proximity wireless communication device is 1 m, the signal transmitted by selecting MCS0 from the proximity wireless communication device is received by the normal wireless communication device. Received at level -78 dBm. Therefore, if the distance between the two is more than 1 m, the normal wireless communication apparatus can transmit the signal without determining that the CCA is busy by the signal from the proximity wireless communication apparatus.

  Here, the carrier sense level used by the proximity type wireless communication apparatus is considered so that the proximity type and the normal type can coexist with each other in a state where the distance between both exceeds 1 m. When the distance between the two is 1 m, a signal transmitted by selecting MCS0 from the normal wireless communication apparatus is received at a reception level of −68 dBm in the proximity wireless communication apparatus. This reception level −68 dBm is higher than the required MCS0 reception sensitivity −78 dBm. As is clear from the above-described example, a signal transmitted by selecting MCS0 with a transmission power of 10 dBm finally has a reception sensitivity of −78 dBm at a position 3 m away. Therefore, even if the proximity wireless communication apparatus is moved a little further than 1 m from the normal wireless communication apparatus, the reception level exceeds −78 dBm. Therefore, the proximity wireless communication apparatus uses the signal from the normal wireless communication apparatus. The CCA is determined to be busy.

  Therefore, the wireless communication apparatus according to the present embodiment sets the carrier sense level higher than, for example, −68 dBm so that the CCA is not determined to be busy even in such a situation. Assuming that the maximum communication range of the proximity method is 3 cm, it is assumed that the reception level at a position 3 cm away when a signal is transmitted by selecting MCS0 with a transmission power of 0 dBm is −48 dBm. Under such conditions, the wireless communication apparatus according to the present embodiment sets the carrier sense level of MCS0 to −48 dBm. That is, the PHY processing unit 40 determines that the CCA is busy when the reception level is −48 dBm or more, and notifies the MAC processing unit 10 that the CCA is busy. Then, the PHY processing unit 40 extracts a payload from a PHY packet that has been successfully received when the reception level is −48 dBm or more, and passes the payload to the MAC processing unit 10 as a MAC frame.

  Even if the reception level is somewhat lower than −48 dBm, the reception level is sufficiently higher than the reception performance (reception sensitivity) of the wireless communication device, so the wireless communication device may be able to successfully receive this signal. However, the PHY processing unit 40 does not determine that the CCA is busy when the reception level is less than −48 dBm (that is, determines that the CCA is idle), and the CCA is busy to the MAC processing unit 10. Not notify you. Further, the PHY processing unit 40 does not pass the payload of the PHY packet to the MAC processing unit 10. Therefore, the wireless communication apparatus according to the present embodiment also performs the virtual carrier sense at the MAC level described above based on the MAC frame from the PHY packet that has been successfully received when the reception level is −48 dBm.

Next, the operation when receiving a PHY packet using MCS of MCS1 or higher will be considered.
First, consider the case where MCS0 and MCS1-12 are categorized as the same PHY system. In this case, the wireless communication apparatus may use −48 dBm as the carrier sense level for all MCSs. That is, the PHY processing unit 40 may determine that the CCA is busy if the reception level is −48 dBm or more for an arbitrary MCS, and may determine that the CCA is idle otherwise.

  Next, consider the case where MCS0 and MCS1 to 12 are categorized as different PHY methods. As described above, if the minimum reception sensitivity of MCS1 of −68 dBm is used as the carrier sense level in the normal method, the difference between the carrier sense level of MCS0 and the carrier sense level of MCS1 in the normal method is 10 dB. However, as described above, when the transmission power is limited to 0 dBm, the reception level at a position 3 cm away is −48 dBm (that is, the carrier sense level of MCS0 in the proximity method). This reception level is 20 dB higher than the minimum reception sensitivity of MCS1 in the normal method -68 dBm. Therefore, the wireless communication apparatus can sufficiently receive the MCS1 signal even if the carrier sense level of MCS1 is set to −48 dBm, which is the same as that of MCS0, in the proximity method.

  That is, the difference (for example, −68 dBm) of the minimum reception sensitivity (for example, −68 dBm) of a given MCS (for example, MCS1) with respect to the minimum reception sensitivity (for example, −78 dBm) of the MCS (for example, MCS0) with the lowest transmission speed in the proximity method. 10 dB) is equal to or less than the difference (for example, 30 dB) of the proximity type carrier sense level (for example, −48 dBm) with respect to the normal type carrier sense level (for example, −78 dBm), A signal of a given MCS can be received. On the other hand, if the difference in the minimum reception sensitivity of a given MCS with respect to the minimum reception sensitivity of the MCS at the lowest transmission rate in the proximity method is larger than the difference in the carrier sense level of the proximity method with respect to the carrier sense level of the normal method, The communication range of a given MCS is narrower than the communication range (eg, 3 cm) of the MCS with the lowest transmission rate. The narrowing of the communication range as the MCS transmission rate increases is the same as so-called link adaptation, so there is no problem. Therefore, even when MCS0 and MCS1 to MCS12 are categorized as different PHY methods, the wireless communication apparatus may use one carrier sense level (for example, −48 dBm) for the proximity method. That is, the PHY processing unit 40 may determine that the CCA is busy if the reception level is −48 dBm or more for an arbitrary MCS, and may determine that the CCA is idle otherwise.

  As described above, when receiving a signal other than the corresponding PHY method, the wireless communication device uses a value obtained by adding 20 dB to the minimum reception sensitivity of the PHY method as the carrier sense level. However, even if 20 dB is added to the minimum reception sensitivity (−68 dBm) of MCS1, it does not exceed the carrier sense level −48 dBm for the proximity method. Therefore, the wireless communication apparatus may use one carrier sense level (for example, −48 dBm) for the proximity method even when the fixed value is considered. That is, the PHY processing unit 40 may determine that the CCA is busy if the reception level is −48 dBm or more for an arbitrary MCS, and may determine that the CCA is idle otherwise.

  By the way, as one of the reasons why MCS0 and MCS1-12 are categorized as different PHY systems in the normal system, in general, the PHY system (ie, MCS1-12) at the time of data frame exchange in millimeter wave band communication is a high antenna. Use of gain (directivity) can be mentioned. Here, MCS0 is designed as a PHY system that covers a wide communication range in order to make the existence of one wireless communication group known to the surroundings. Specifically, MCS0 is designed as a robust PHY system having the widest directivity width that can be practically achieved in the millimeter wave band (ie, quasi-omni). On the other hand, the MCSs 1 to 12 are designed in accordance with a policy that radio communication apparatuses actively use directivity to actually exchange data frames. Specifically, the MCSs 1 to 12 are designed as a PHY system that provides high transmission speed after increasing antenna gain by performing directivity training.

  On the other hand, in the proximity method, it is often required to find a communication partner in a short time, establish a communication link and exchange data frames, so the PHY method is designed with a policy that does not necessarily actively use directivity. May be. That is, the proximity method may not be designed to transmit a management frame such as a Beacon frame by MCS0 unlike the normal method, and the management frame may be designed to be transmitted by MCS 1 to 12 like the data frame. Absent. In this case, the proximity method does not use MCS0 but uses one PHY method (MCS1 to 12). However, as described above, the proximity method achieves the transmission speed of MCS1 at a position 3 cm away. It may be read as “It is required”.

  Furthermore, the proximity scheme may be designed to be used only for some MCSs of MCS 1-12 depending on transmission rate requirements. Also in this case, the wireless communication apparatus may provide one carrier sense level higher than the minimum reception sensitivity in the PHY method to be used, and determine CCA busy / idle based on this value.

  As described above, the wireless communication apparatus according to the first embodiment uses the maximum transmission power limited to be lower than that of the normal method (for example, the normal method is 10 dBm and the proximity method is 0 dBm), and The proximity wireless communication is performed by the proximity method using a carrier sense level higher than that of the normal method (for example, the normal method is -78 dBm and the proximity method is -48 dBm). Therefore, according to the wireless communication device according to the present embodiment, the criteria for detecting interference with respect to signals from other wireless communication devices are stricter than the normal method, and the proximity wireless communication device is the normal method. The situation of being inferior to the wireless communication device is eliminated. That is, the normal-type wireless communication apparatus and the proximity-type wireless communication apparatus can coexist on an equal basis.

  As is clear from the above consideration, when a normal type wireless communication device is arranged very close to a wireless communication device using the proximity method, the wireless communication device has a high carrier sense level for the proximity method. Even if set, interference will be detected. In such a case, it is desirable for the wireless communication device to move to another frequency channel without interference. The same applies to a case where a normal wireless communication apparatus starts wireless communication very close after the proximity wireless communication apparatus starts wireless communication. Of course, the same applies when the wireless communication apparatuses of different BSSs using the proximity method are extremely close to each other. Generally speaking, these phenomena are the same as the interference between wireless communication apparatuses of different BSSs (that is, wireless communication groups) using the normal method, and therefore, similar measures may be taken. That is, it is possible to appropriately apply detection of interference in the normal method, change of the frequency channel of the BSS, and the like.

  Further, the carrier sense level and the maximum transmission power for the proximity method include, for example, a functional unit that manages the MAC processing unit 10 (for example, a MAC / PHY management unit 70 described later) or a part of the functional unit. It may be set by the MAC processing unit 10. Also, the carrier sense level and the maximum transmission power for the proximity method may be set automatically when the proximity method is used, or may be set according to an instruction from a human such as a user.

(Second Embodiment)
The wireless communication apparatus according to the second embodiment supplements the wireless communication apparatus according to the first embodiment described above. The wireless communication apparatus according to the present embodiment supports both the proximity method and the normal method described above, and can operate by selecting one as necessary. Note that the wireless communication apparatus according to the present embodiment selects the normal method by default.

  As illustrated in FIG. 3, the wireless communication apparatus according to the present embodiment includes a host processing unit 100, a MAC processing unit 10, a PHY processing unit 40, a frequency conversion circuit 50, an antenna 60, and a MAC / PHY management unit 70. .

  The MAC / PHY management unit 70 is connected to the host processing unit 100, the MAC processing unit 10 (more specifically, the reception processing unit 20 and the transmission processing unit 30), and the PHY processing unit 40. The MACH / PHY management unit 70 manages the MAC operation and the PHY operation in the wireless communication apparatus.

  The MAC / PHY management unit 70 corresponds to an SME (Station Management Entity) in the IEEE 802.11 wireless LAN. An interface between the MAC / PHY management unit 70 and the MAC processing unit 10 corresponds to an MLME SAP (MAC subLayer Management Service Access Point) in the IEEE 802.11 wireless LAN. The interface between the MAC / PHY management unit 70 and the PHY processing unit 40 corresponds to PLME SAP (Physical Layer Management Entity Access Point) in the IEEE 802.11 wireless LAN.

  In FIG. 3, the MAC / PHY management unit 70 is depicted as if the functional unit for MAC management and the functional unit for PHY management are integrated, but the following operations can be realized. It may be implemented in a different manner.

  The MAC / PHY management unit 70 holds an information management base (MIB). In the MIB, various information for realizing the proximity method is held.

  For example, the MIB holds an attribute indicating whether or not to operate in the proximity method (whether or not to select an attribute for the proximity method). Such an attribute can be named, for example, dot11CloseProximityCommunicationEnabled. The attribute is set to a TRUE value when the wireless communication device uses the proximity method, and is set to a FALSE value when the wireless communication device uses the normal method. As described above, the default value of the attribute is FALSE (normal system).

  For example, when the user selects an application for the proximity method, an instruction to rewrite the value of dot11CloseProximityCommunicationEnabled to TRUE is given to the MAC / PHY management unit 70 via the upper processing unit 100. The MAC / PHY management unit 70 rewrites the value of dot11CloseProximityCommunicationEnabled to TRUE according to the instruction. Alternatively, when the upper processing unit 100 selects the proximity method by some algorithm, the rewriting instruction may be given to the MAC / PHY management unit 70. In addition, when the user selects the proximity method, the upper processing unit 100 may give a rewrite instruction to the MAC / PHY management unit 70, or the MAC / PHY management unit 70 may perform rewriting spontaneously. .

  Note that a wireless communication device that supports only the normal method (in other words, does not support the proximity method) does not hold (does not need to hold) the attribute dot11CloseProximityCommunicationEnabled.

  Further, the MIB also holds attributes for designating the maximum transmission power and carrier sense level used in the proximity method. The attribute that specifies the maximum transmission power can be named, for example, dot11CloseProximityCommunicationMaximumTransmitPowerLevel. The attribute that specifies the carrier sense level can be named, for example, dot11CloseProximityCommunicationCarrierSenseLevel. According to the first embodiment described above, the value of dot11CloseProximityMaximumTransmitPowerLevel is set to, for example, 0 dBm, and the value of dot11CloseProximityCommunicationCarrierSenseLevel is set to, for example, -48 dBm. Both attribute values may be fixed or may be changed by the upper processing unit 100 or the like.

  Alternatively, an attribute for designating another parameter can be prepared instead of designating the maximum transmission power and carrier sense level itself used in the proximity method. For example, instead of the maximum transmission power of the proximity method, an attribute for designating a reduction amount of the maximum transmission power of the proximity method relative to the maximum transmission power of the normal method (for example, 10 dB according to the first embodiment) may be prepared. Instead of the proximity type carrier sense level, an attribute for specifying an increase amount (for example, 30 dB according to the first embodiment) of the proximity type carrier sense level with respect to the minimum reception sensitivity of the PHY method may be prepared.

  The PHY processing unit 40 operates according to the proximity method when the value of the dot11CloseProximityCommunicationEnabled is TRUE. That is, the PHY processing unit 40 performs transmission so that the transmission power is equal to or less than the value of dot11CloseProximityMaximumTransmitPowerLevel. The PHY processing unit 40 determines that the CCA is busy / idle based on the value of the dot11CloseProximityCommunicationCarrierSenseLevel.

  On the other hand, the PHY processing unit 40 operates according to the normal method when the value of the dot11CloseProximityCommunicationEnabled is FALSE. That is, the PHY processing unit 40 performs transmission so that the transmission power is equal to or less than the maximum transmission power of the normal method. Further, the PHY processing unit 40 determines that the CCA is busy / idle based on the minimum reception sensitivity of the PHY method. It is preferable that the normal maximum transmission power is also maintained in the MIB. An attribute that specifies the maximum transmission power of the normal method can be named, for example, dot11MaximumTransmitPowerLevel.

  The transmission power used by the PHY processing unit 40 may be fixed to the maximum transmission power of the proximity method or the normal method. Alternatively, the MAC processing unit 10 (more specifically, the transmission processing unit 30) may designate a transmission power equal to or lower than the maximum transmission power of the proximity method or the normal method and notify the PHY processing unit 40 of it. Alternatively, the user may specify a transmission power that is equal to or less than the maximum transmission power of the proximity method or the normal method. In such a case, the transmission power specified by the user may be notified to the PHY processing unit 40 via the MAC / PHY management unit 70.

  Furthermore, the MIB does not necessarily have to be held in the MAC / PHY management unit 70. For example, the MIB may be held in a common memory unit (not shown). The MIB held in the common memory unit can be referred to (readable) from the MAC / PHY management unit 70, the MAC processing unit 10, and the PHY processing unit 40, and the MAC / PHY management unit 70 sets rewritable attributes. It may be designed to be rewritable.

  As described above, the wireless communication apparatus according to the second embodiment holds various attributes for the proximity method in the MIB. Therefore, the wireless communication apparatus according to the present embodiment supports both the proximity method and the normal method, and can operate by selecting one as necessary.

(Third embodiment)
The wireless communication apparatus according to the third embodiment supplements the wireless communication apparatus according to the first or second embodiment described above. This embodiment describes the formation and maintenance of a proximity wireless communication group (for example, BSS in IEEE 802.11). That is, according to the present embodiment, wireless communication devices that support the proximity method form a proximity method BSS.

  In general, when a BSS is formed in IEEE 802.11, a wireless communication device that transmits a Beacon frame (management frame) (in this embodiment, a wireless communication device in this role is referred to as a first wireless communication device for convenience). And a wireless communication device that receives a Beacon frame (in this embodiment, the wireless communication device having such a role is referred to as a second wireless communication device for convenience). The second wireless communication apparatus adjusts its own operation to match the attribute of the BSS based on the information in the received Beacon frame and also transmits its own information (for example, a timer value described later) in the received Beacon frame. Synchronize with the synchronization information. The first wireless communication device transmits a Beacon frame for forming and maintaining the BSS in a period before the BSS is formed (that is, there is no second wireless communication apparatus participating in the BSS) and in a period after the BSS is formed. Are transmitted periodically.

  The second wireless communication device may search for the first wireless communication device by receiving the Beacon frame (so-called passive scan). Alternatively, the second wireless communication apparatus transmits a management frame (for example, a Probe Request frame in IEEE 802.11) for searching for the first wireless communication apparatus in order to shorten the search time, and the first communication apparatus The first wireless communication device may be searched by receiving the response frame (for example, a Probe Response frame in IEEE 802.11) (so-called active scan). The Probe Response frame stores the same information as the Beacon frame. Therefore, the second wireless communication apparatus can acquire necessary information from the Probe Response frame instead of the Beacon frame.

  The Beacon frame is basically transmitted in an omni direction. However, in the millimeter wave band, the antenna pattern is assumed to be quasi-omni depending on the design. In such a case, it is necessary for the wireless communication apparatuses to align the direction of the antenna pattern to some extent. Therefore, the second wireless communication apparatus that performs active scan (transmits a probe request) may first transmit a Beacon frame to the first wireless communication apparatus.

  Here, it is assumed that the proximity-type BSS is a wireless communication group formed by a plurality of wireless communication apparatuses using the proximity method. Therefore, with some exceptions, a wireless communication device that does not support the proximity method cannot participate in the proximity method BSS.

  The wireless communication apparatus according to the present embodiment stores information indicating that the BSS attribute is the proximity method in the frame body field of the Beacon frame / Probe Response frame transmitted for the proximity method BSS. Therefore, the wireless communication apparatus that receives these Beacon frame / Probe Response frame can recognize whether or not the searched BSS is of the proximity method.

  As illustrated in FIG. 4, the wireless communication device according to the present embodiment includes a MAC common processing unit 15 in the MAC processing unit 10. The MAC common processing unit 15 exchanges signals with the MAC / PHY management unit 70. Specifically, the MAC common processing unit 15 once receives an instruction from the MAC / PHY management unit 70, converts the instruction into one suitable for the reception processing unit 20 and the transmission processing unit 30, and outputs it. The MAC common processing unit 15 is also connected to the upper processing unit 100. Therefore, the MAC common processing unit 15 mediates the transfer of received data from the reception processing unit 20 to the upper processing unit 100 and the transmission of transmission data from the upper processing unit 100 to the transmission processing unit 30.

  Hereinafter, the operation when the wireless communication apparatus according to the present embodiment stores information indicating that the BSS attribute is the proximity method in the frame body field of the Beacon frame / Probe Response frame transmitted from the proximity type BSS. Will be described.

  The wireless communication apparatus according to the present embodiment holds the attribute dot11CloseProximityCommunicationEnabled in the MIB, as in the second embodiment described above. When the MAC / PHY management unit 70 outputs an instruction to start BSS (formation) (for example, a primitive called MLME-START.request in IEEE 802.11), the transmission process of the Beacon frame starts. When the MAC common processing unit 15 receives the above instruction, the MAC common processing unit 15 refers to the value of the dot11ClosePoximityCommunicationEnabled. If the value is TRUE, the MAC common processing unit 15 generates a frame body that stores information indicating that the BSS attribute is the proximity method, and sends a transmission instruction for a Beacon frame including the frame body to the transmission processing unit 30. Give periodically. The transmission period (Beacon Interval or Beacon Period) of this Beacon frame is specified, for example, in the instruction to start the BSS. Alternatively, the transmission cycle may be specified in the MIB. In such a case, the MAC common processing unit 15 may refer to the MIB. The transmission processing unit 30 transmits the Beacon frame via the PHY processing unit 40, the frequency conversion circuit 50, and the antenna 60 based on the carrier sense information from the reception processing unit 20.

  On the other hand, when the wireless communication device according to the present embodiment receives a Probe Request frame from another wireless communication device (corresponding to the second wireless communication device), the reception processing unit 20 transmits the Probe Request frame to the MAC common processing unit. Pass to 15. The MAC common processing unit 15 generates a frame body of the Probe Response frame and passes it to the transmission processing unit 30 when the request condition specified in the frame body of the Probe Request frame is satisfied. However, the MAC common processing unit 15 generates the frame body of the Probe Response frame according to the value of dot11ClosePoximityCommunicationEnabled. Specifically, if the value is TRUE, the MAC common processing unit 15 needs to generate a frame body that stores information indicating that the BSS attribute is the proximity method. Based on the carrier sense information from the reception processing unit 20, the transmission processing unit 30 transmits a Probe Response frame via the PHY processing unit 40, the frequency conversion circuit 50, and the antenna 60.

  Information indicating that the attribute of the BSS is a proximity method can be stored in the frame body field of the Beacon frame / Probe Response frame in the manner exemplified below. If a field indicating the BSS attribute is prepared in the normal method and a part of the field is reserved, it can be defined that information related to the reserved part is stored. For example, the proximity method is used only in the millimeter wave band, and there is a normal method as a base of the proximity method in this millimeter wave band, and the field indicating the operation attribute in the millimeter wave band is a frame of the Beacon frame / Probe Response frame. It is assumed that an information element (IE) is prepared in the body field, and one or more bits are reserved in the field indicating the operation attribute. In such a case, it can be defined that information indicating whether the attribute of the BSS in operation is a proximity method is stored in 1 bit of Reserved. That is, the MAC common processing unit 15 sets the value of the 1 bit to 1 if the attribute of the BSS in operation is the proximity method, and otherwise (for example, if the attribute of the BSS in operation is the normal method). For example, the 1-bit value may be left as 0.

  Then, the wireless communication device that supports the proximity method (corresponding to the second wireless communication device) extracts, for example, an IE indicating an operation attribute in the millimeter wave band, and determines whether or not the attribute of the BSS is the proximity method. It is possible to recognize whether or not the BSS is operated in the proximity mode by referring to the value of the bit storing the information to be indicated. On the other hand, a wireless communication apparatus that does not support the proximity method may ignore this because it does not need to recognize a bit for storing information indicating whether the attribute of the BSS is the proximity method. Alternatively, a wireless communication apparatus that does not support the proximity method recognizes that 1 is set to the bit that should be originally reserved, that is, 0, and a wireless communication method that is not supported by itself is requested in the BSS. You may refrain from participating in the BSS.

Next, an operation when the wireless communication apparatus according to the present embodiment (that is, a wireless communication apparatus that supports at least the proximity method) participates in the BSS will be described.
When the MAC / PHY management unit 70 determines to search for the BSS, it outputs a BSS search instruction to the MAC common processing unit 15. This search instruction is in accordance with MLME-SCAN. This corresponds to a request primitive. This primitive has the parameters illustrated in FIG.

  When passive scanning is instructed by the parameter Scan Type, the MAC common processing unit 15 refers to the parameter Channel List and gives an instruction to the PHY processing unit 40 to move to the designated frequency channel. Then, the MAC common processing unit 15 collects the information of the Beacon frame in the management frame received via the PHY processing unit 40 and the reception processing unit 20 at a time equal to or higher than the Min Channel Time and equal to or lower than the Max Channel Time. Here, if the BSS search instruction includes a restriction on the target condition, the MAC common processing unit 15 collects only the information of the Beacon frame that satisfies the target condition. If a plurality of frequency channels are designated in the Channel List, the MAC common processing unit 15 performs the passive scan operation for each designated frequency channel. When a series of passive scan operations are completed, the MAC common processing unit 15 passes the collected Beacon frame information to the MAC / PHY management unit 70.

  On the other hand, when an active scan is instructed by the parameter Scan Type, the MAC common processing unit 15 generates a frame body of a Probe Request frame in accordance with the input instruction. The MAC common processing unit 15 passes the Probe Request frame to the transmission processing unit 30 so that the Probe Request frame is transmitted in accordance with the BSS search condition (for example, the parameter Probe Delay in FIG. 6) in each designated frequency channel. Unlike the passive scan, the MAC common processing unit 15 collects information of the Probe Response frame instead of the Beacon frame. Similar to the passive scan, if a plurality of frequency channels are designated in the Channel List, the MAC common processing unit 15 performs the active scan operation for each designated frequency channel. When the series of active scan operations is completed, the MAC common processing unit 15 passes the collected probe response frame information to the MAC / PHY management unit 70.

  As illustrated in FIG. 6, the BSS search instruction from the MAC / PHY management unit 70 can include a parameter BSS Type that specifies the type of BSS to be scanned. If it is possible to specify whether or not this parameter is a proximity-type BSS, the MAC common processing unit 15 uses the parameter when collecting information of the Beacon frame / Probe Response frame. can do. That is, when the MAC / PHY management unit 70 gives the MAC processing unit 15 a search instruction including a BSS Type that designates the proximity type BSS, the MAC processing unit 15 stores information indicating that the attribute of the BSS is the proximity type. Only beacon frames / probe response frames are collected.

  Further, if the MAC / PHY management unit 70 gives a search instruction including the BSS Type for designating the proximity type BSS to the MAC common processing unit 15, the MAC / PHY management unit 70 accordingly sets the value of the attribute dot11CloseProximityCommunicationEnabled to TRUE. It is effective to rewrite to As a result of the rewriting process, the PHY processing unit 40 uses the carrier sense level for the proximity method. In other words, the MAC common processing unit 15 collects only a Beacon frame / Probe Response frame with a reception level equal to or higher than the carrier sense level. Therefore, the MAC processing unit 15 can confirm that a signal from the BSS corresponding to the collected Beacon frame / Probe Response frame is received at a carrier sense level or higher for the proximity method before joining the BSS. . Therefore, according to the rewriting process, it is possible to avoid a situation in which the signal from the BSS to be joined does not satisfy the carrier sense level for the proximity method, and the proximity wireless communication is disabled.

  The MAC / PHY management unit 70 determines a BSS to participate based on the information of the Beacon frame / Probe Response frame collected by the MAC common processing unit 15 through the passive scan / active scan. The MAC / PHY management unit 70 gives an instruction to participate in a specific BSS (for example, MLME-JOIN.request primitive in IEEE 802.11) to the MAC common processing unit 15.

  By the way, for example because the application request permits both the normal method and the proximity method, the upper processing unit 100 instructs the MAC / PHY management unit 70 to search for the BSS without specifying either the normal method or the proximity method. May give. Here, the value of the attribute dot11CloseProximityCommunicationEnabled is FALSE. The MAC / PHY management unit 70 gives the MAC common processing unit 15 a BSS search instruction that does not specify the BSS type (proximity method). Also in this case, the MAC processing unit 15 can collect the information of the beacon frame / probe response frame of the proximity BSS and notify the MAC / PHY management unit 70 of the information. However, since the value of dot11CloseProximityCommunicationEnabled is FALSE as described above, the wireless communication apparatus uses the normal transmission power and carrier sense level. In other words, more precisely, if there is a proximity BSS that transmits a signal that can obtain a reception power equal to or higher than the normal carrier sense level, the MAC processing unit 15 uses the proximity BSS Beacon frame / Probe Response frame. Information can be collected.

  However, when a wireless communication device participates in a proximity BSS, it is necessary to rewrite the value of dot11CloseProximityCommunicationEnabled to TRUE and use the transmission power and carrier sense level for the proximity method. Therefore, it is not equivalent that the wireless communication device can scan the proximity BSS and that the wireless communication device can realize the proximity wireless communication by participating in the BSS. Specifically, the reception level of the scanned signal from the proximity type BSS becomes lower than the proximity type carrier sense level, and the proximity wireless communication may be disabled.

  Therefore, if the wireless communication apparatus according to the present embodiment supports both the normal method and the proximity method as in the second embodiment, the following operation is effective. Specifically, the MAC common processing unit 15 adds the reception level of the frame to the information of the Beacon frame / Probe Response frame (that is, the information of the BSS) collected by the scan operation, and notifies the MAC / PHY management unit 70 of it. . This notification is sent to MLME-SCAN. It corresponds to a confirm primitive. If this primitive is assumed, the above operation can be realized by adding an item describing the reception level to a parameter called BSSDescription that collectively represents each BSS information. For example, the PHY processing unit 40 passes the reception level of the MAC frame to the reception processing unit 20 in addition to the MAC frame. The reception processing unit 20 passes the reception level of the frame to the MAC common processing unit 15 in addition to at least the information of the Beacon frame / Probe Response frame. The MAC common processing unit 15 can pass the reception level of the Beacon frame / Probe Response frame to the MAC / PHY management unit 70 as information accompanying each BSS in addition to the scan result. If the attribute of the scanned BSS is a proximity method, the MAC / PHY management unit 70 determines whether or not it can participate in the BSS of the proximity method based on the reception level (if it participates, the carrier sense level of the proximity method) It may be determined whether or not the above reception level can be obtained.

  Further, for example, dot11CloseProximityImplemented can be defined as an attribute indicating whether or not the wireless communication device supports the proximity method. This attribute is held in the MIB, for example. That is, if this attribute value is TRUE (indicating that the proximity method is supported), the MAC common processing unit 15 performs MAC / PHY management on the reception level of each BSS Beacon frame / Probe Response frame in addition to the scan result. What is necessary is just to pass to the part 70. On the other hand, if the attribute value is FALSE (indicating that the proximity method is not supported), the MAC common processing unit 15 simply passes the scan result to the MAC / PHY management unit 70 (that is, the reception level is set to the MAC level). / PHY management unit 70). Further, if the attribute is not defined, the MAC common processing unit 15 considers that the wireless communication device does not support the proximity method, and may behave in the same manner as when the attribute value is FALSE. If dot11CloseProximityCommunicationImplemented is defined and this attribute value is TRUE, the aforementioned attribute dot11CloseProximityCommunicationEnabled is also defined, and the value of TRUE or FALSE is set.

  For example, the MAC / PHY management unit 70 collects valid BSS candidates (that is, confirmation of proximity wireless communication is possible when participating, for example, based on reception levels) and application requests in higher layers. Based on the above, the participating BSS is determined. If the determined BSS attribute is the proximity method, the MAC / PHY management unit 70 rewrites the value of the attribute dot11CloseProximityCommunicationEnabled to TRUE, and switches to the transmission power and carrier sense level of the proximity method. Note that the operation of joining the proximity system BSS is the same as that in the normal system. That is, the wireless communication apparatus receives the proximity type BSS Beacon frame, adjusts its own operation to match the attribute of the BSS based on the information in the received Beacon frame, and also transmits its own information (for example, described later). Timer value) is synchronized with the synchronization information in the received Beacon frame.

  Information indicating that the BSS attribute is the proximity method may be stored in an association response frame. The Association Response frame is transmitted by the first wireless communication apparatus to the second wireless communication apparatus when the second wireless communication apparatus transmits an association request (Association Request) frame to the first wireless communication apparatus. The If information indicating that the BSS attribute is the proximity method is stored in the Association Response frame, the second wireless communication apparatus can confirm that the BSS attribute is the proximity method in the association process.

  The above description describes the operation when the wireless communication apparatus according to the present embodiment participates in the proximity-type BSS and the operation when the wireless communication apparatus according to the present embodiment operates the proximity-type BSS. By the way, regarding close proximity wireless communication, there is assumed a requirement specification that a wireless communication device using the proximity method wants to communicate only with a wireless communication device similarly using the proximity method. According to the required specifications, it is preferable to exclude or restrict a wireless communication device that does not support the proximity method from participating in the proximity method BSS. In the following description, when the wireless communication apparatus according to the present embodiment operates a proximity-type BSS, an operation when a wireless communication apparatus that does not support the proximity method is excluded or restricted from participating in the BSS will be described.

  In IEEE 802.11, the definition of participation in a BSS is that the second wireless communication apparatus adjusts its operation to match the attribute of the BSS and synchronizes its information with synchronization information. ing. Therefore, the second wireless communication apparatus can participate in the BSS without going through an authentication procedure by frame exchange with the first wireless communication apparatus. If the value of the attribute dot11CloseProximityImplemented is TRUE and the second wireless communication apparatus wishes to participate in a normal BSS, the BSS attribute is a proximity method such as a Beacon frame. And may refrain from participating in the proximity-type BSS. However, if the value of this attribute is FALSE or this attribute is not defined, the second wireless communication apparatus does not support the proximity method (supports only the normal method). Therefore, the second wireless communication apparatus may not recognize that the BSS attribute is the proximity method. That is, a wireless communication apparatus that does not support the proximity method may adjust its own operation to match the attribute of the BSS, and may synchronize its own information with the synchronization information and participate in the proximity type BSS. Therefore, it is not easy to exclude or restrict the wireless communication device that does not support the proximity method itself from participating in the proximity method BSS. Therefore, first, a method for eliminating or limiting the transmission of a data frame to a wireless communication apparatus that participates in a proximity-type BSS by a wireless communication apparatus that does not support the proximity system will be described.

  In IEEE 802.11, an association process is prepared. Then, in the proximity type BSS, it can be determined that the exchange of the data frames cannot be started unless the association process is performed. That is, a wireless communication apparatus participating in a proximity BSS needs to complete the association process before starting the exchange of data frames.

  The second wireless communication device transmits an association request frame to the first wireless communication device in the association process. In the frame body field, the second wireless communication device determines whether or not the second wireless communication device supports the proximity method. Stores the information indicated. For example, the proximity method is used only in the millimeter wave band, and there is a normal method as a base of the proximity method in this millimeter wave band, and the capability of the wireless communication device in the millimeter wave band (in the association request frame of the normal method) It is assumed that a field indicating (capability) is included and one or more bits are reserved in this field. In such a case, it can be defined that information indicating whether or not the second wireless communication apparatus supports the proximity method is stored in 1 bit of Reserved. That is, if the value of the attribute dot11CloseProximity Implementation Implemented is TRUE and the value of the attribute dot11CloseProximityCommunicationEnabled is FALSE (default), the MAC common processing unit 15 of the second wireless communication apparatus instructs the MAC / PHY management unit 70 to When the frame body of the Association Request frame is generated, 1 is set to the specific 1 bit. On the other hand, if the value of the attribute dot11CloseProximityCommunicationImplemented is FALSE, the MAC common processing unit 15 of the second wireless communication apparatus keeps the specific 1 bit as 0.

  Then, the first wireless communication apparatus that operates the proximity-type BSS receives the Association Request frame and confirms the value of the specific 1 bit. If the value of the specific 1 bit is 0, the first wireless communication apparatus rejects the association. Specifically, the first wireless communication apparatus sets “Reject” in the Status Code in the Association Response frame, and transmits this Association Response frame to the second wireless communication apparatus. Here, the reason that the Status Code does not support the proximity method may be added. On the other hand, if the value of the specific 1 bit is 1, the first wireless communication apparatus can permit association depending on other conditions. When permitting the association, the first wireless communication apparatus sets Successful in the Status Code in the Association Response frame, and transmits this Association Response frame to the second wireless communication apparatus. When recognizing that the association is permitted by the Association Response frame, the second wireless communication apparatus rewrites the value of the attribute dot11CloseProximityCommunicationEnabled to TRUE and starts using the proximity method.

  In the above description, when the value of the attribute dot11CloseProximationImplemented is TRUE and the value of the attribute dot11CloseProximityCommunicationEnabled is FALSE, 1 is set for one specific bit of the Association Request frame. According to the above method, the value of the attribute dot11CloseProximityCommunicationEnabled remains FALSE until the association is permitted. That is, switching between using and not using a proximity method by a wireless communication device depends on a response from another wireless communication device.

  Therefore, the above method can be modified as follows. Specifically, as described above, a wireless communication device that supports the proximity method (the value of the attribute dot11CloseProximityImplementedImplementation is TRUE) determines that the wireless communication device decides to participate in the proximity method BSS and sets the value of the attribute dot11CloseProximityEnabled to TRUE. Can be rewritten. Even when such a wireless communication apparatus transmits an Association Request frame, it is effective to set 1 to the specific 1 bit. Specifically, for example, the MAC / PHY management unit 70 obtains the scan result (search information of the surrounding BSS) from the MAC common processing unit 15 by MLME-SCAN. Receive using confirm. The MAC / PHY management unit 70 can select a proximity-type BSS from the scan results and decide to participate in the BSS. MAC / PHY management unit 70 is MLME-JOIN. Request is used to instruct the MAC common processing unit 15 to participate in the proximity-type BSS, and the value of the attribute dot11CloseProximityCommunicationEnabled is rewritten to TRUE. Then, the MAC / PHY management unit 70 performs MLME-ASSOCATION. The request is output to the MAC common processing unit 15, and the MAC common processing unit 15 generates a frame body of the Association Request frame accordingly. Here, the MAC common processing unit 15 refers to the value of the attribute dot11CloseProximityCommunicationEnabled, and if the value is TRUE, sets 1 in the specific 1 bit in the frame body field of the Association Request frame. On the other hand, if the value of the attribute dot11CloseProximityCommunicationEnabled is FALSE, the MAC common processing unit 15 leaves the specific 1 bit in the frame body of the Association Request frame as 0. According to this method, the wireless communication device uses the transmission power and the carrier sense level of the proximity method when transmitting the Association Request frame. Therefore, the wireless communication apparatus can confirm whether or not the frame exchange related to the association is performed in the proximity communication range. Specifically, if the wireless communication device cannot receive the association response frame even after waiting for a certain time from transmission of the association request frame, the wireless communication device receives the association request frame at the communication partner (that is, the first wireless communication device). It can be considered that the level was lower than the proximity type carrier sense level. That is, the wireless communication device can be regarded as the distance from the communication partner exceeding the communication range of the proximity method. Note that the MAC / PHY management unit 70 designates the length of time to wait for the Association Response frame, and sends the MLME-ASSOCATION. When giving a request, the time length can be notified in the primitive.

Next, a method for excluding or restricting a wireless communication apparatus that does not support the proximity method from participating in the proximity method BSS and transmitting data frames will be described.
For example, the first wireless communication apparatus can schedule a wireless communication apparatus that does not permit association to transmit a data frame in the Beacon Interval. If there is a mechanism in which a wireless communication apparatus participating in the BSS transmits a frame according to a transmission schedule in the Beacon Interval in the normal method that is the base of the proximity method, this mechanism can also be used in the proximity method. . Specifically, as illustrated in FIG. 5, the first wireless communication apparatus can transmit a management frame such as an Association Request frame only for a certain period in the Beacon Interval, and can also transmit a Beacon Interval It is only necessary to schedule so that the data frame can be transmitted only to the first wireless communication apparatus or the wireless communication apparatus permitted to associate by the first wireless communication apparatus in all remaining periods. The schedule information is notified to each wireless communication device by a Beacon frame.

  In FIG. 5, the first wireless communication apparatus is represented by “STA1”, and one wireless communication apparatus that the first wireless communication apparatus has allowed to associate is represented by “STA2”. That is, according to the example of FIG. 5, a period in which the wireless communication devices other than STA1 and STA2 can transmit data frames is not scheduled. In FIG. 5, the management frame transmittable period is for transmitting a management frame such as an Association Request frame. However, the first wireless communication apparatus may specify a certain wireless communication apparatus and give permission for transmission even in the management frame transmittable period.

  A wireless communication device that does not support the proximity method may not recognize that the attribute of the BSS that it participates in is a proximity method, but according to such a schedule, a period during which a data frame can be transmitted is not scheduled, and as a result Cannot send any data frames. Therefore, a wireless communication apparatus that does not support the proximity method may generate an Association Request frame and transmit it to the first wireless communication apparatus in a management frame transmission possible period in the hope that its own transmission period is scheduled. However, a wireless communication apparatus that does not support the proximity method cannot set 1 in a specific bit for storing information indicating whether or not the proximity method is supported in the Association Request frame. Therefore, the first wireless communication apparatus can refuse this association. Even if some management frame for requesting the schedule of the transmission period is defined, the same effect can be obtained by defining the specific 1 bit as in the Association Request frame (ie, proximity) It is possible to reject a schedule request from a wireless communication device that does not support the method, or to exclude a transmission period for the wireless communication device from the schedule).

  It is also effective to limit the period during which a wireless communication device that is not allowed to associate in the Beacon Interval (that is, a wireless communication device that does not support the proximity method) can transmit. Specifically, the management frame transmittable period in the example of FIG. 5 may be replaced with a contention period. In this contention period, frames that can be transmitted are not limited to management frames, and further, wireless communication apparatuses that can transmit frames are not limited. According to such a schedule, a wireless communication apparatus that does not support the proximity method can transmit a data frame only during the contention period. It is desirable that the contention period be set sufficiently short so that a transmission request (QoS (Quality of Service) request) of a wireless communication apparatus using the proximity method is satisfied. If the contention period is set sufficiently short, even if a wireless communication device that does not support the proximity method participates in the proximity method BSS, frame transmission from the wireless communication device that uses the proximity method is used for frame transmission from the wireless communication device. Does not substantially interfere with transmission.

  It is also effective to use this mechanism if it is possible to define parameters essential for participating in the BSS with respect to the attributes of the BSS. Specifically, the first wireless communication device is a code that can be understood by a wireless communication device that supports the proximity method and cannot be understood by a wireless communication device that does not support the proximity method. Insert. By inserting such a code, a wireless communication apparatus that does not support the proximity method can be excluded from the BSS of the proximity method. For example, it is assumed that there is an IE indicating an MCS set used in a BSS, and that there is a method for indicating an MCS essential for reception in the BSS in the IE. The first wireless communication device uses this method to define a code that does not actually indicate MCS for the proximity method. A wireless communication device that supports the proximity method understands that the code is defined for the proximity method and can participate in the BSS. On the other hand, a wireless communication apparatus that does not support the proximity method cannot understand the above code and cannot participate in the BSS because the MCS indicated by the code is defined as essential for reception by the BSS. I ca n’t tell you.)

  In addition, in the normal method that is the base of the proximity method, if a frame for expelling the wireless communication device from the BSS is defined, it is also effective to use the frame. Specifically, when the first wireless communication device recognizes that a wireless communication device that does not support the proximity method participates in the BSS of the proximity method, the first wireless communication device transmits the frame to drive out the wireless communication device. That's fine. However, the first wireless communication device may not recognize that a wireless communication device that does not support the proximity method participates in the proximity method BSS until the wireless communication device starts exchanging data frames. .

  As described above, according to the wireless communication device according to the third embodiment, wireless communication devices supporting the proximity method can form a proximity method BSS. In the description of the present embodiment and other embodiments, specific management frames such as a Beacon frame and a Probe Response frame are illustrated, but it goes without saying that these may be replaced with other management frames.

(Fourth embodiment)
The wireless communication apparatus according to the fourth embodiment supplements the wireless communication apparatus according to the first to third embodiments described above. Specifically, the wireless communication apparatus according to the present embodiment enables connection in the proximity method without depending on the network identifier prepared in the normal method.

  For example, IEEE 802.11 defines an SSID (Service Set IDentifier) indicating a network identifier including the BSS as one piece of information indicating the attribute of the BSS. By the way, regarding the proximity method, there may be a use case in which communication is started immediately when wireless communication devices come close to each other. Considering such a use case, even if the normal method requires an SSID, the proximity method may require that the communication partner be not restricted and that the network identifier be unquestioned.

  Therefore, when the proximity method follows the policy of the normal method and it is necessary to determine some SSID, the wireless communication apparatus according to the present embodiment may temporarily determine the SSID using a random number counter, for example. An identifier unique to the wireless communication apparatus that started the BSS of the scheme may be used. Then, the SSID may be ignored among the wireless communication devices participating in the proximity type BSS.

  As described above, the wireless communication apparatus according to the fourth embodiment ignores the network identifier in the proximity type BSS. Therefore, according to the wireless communication apparatus according to the present embodiment, it is possible to realize proximity wireless communication suitable for a use case assumed for the proximity method.

(Fifth embodiment)
The wireless communication apparatus according to the fifth embodiment supplements the wireless communication apparatus according to the first to fourth embodiments described above. The wireless communication apparatus according to the present embodiment reduces the time required to start exchanging data frames in the proximity method compared to the normal method.

  Here, in some use cases of close proximity wireless communication, there is a demand for reducing the time required to start data communication (that is, exchange of data frames). In other words, there is a demand for reducing the setup time of the communication link.

  The communication link setup time collides with the time required to select a channel on which a proximity BSS operates, the time required to search for a proximity BSS, and a wireless communication device that periodically transmits a Beacon frame. Includes elements such as time to negotiate in case. Depending on the use case of proximity wireless communication, only some of these may be relevant.

  First, a reduction in the time required to select a channel on which the proximity BSS operates will be described. According to the first embodiment described above, a higher carrier sense level is used in the proximity method than in the normal method (minimum receiving sensitivity of the physical method), so the probability of detecting interference in the proximity method is higher than that in the normal method. Become lower. Therefore, when selecting a channel on which a BSS operates in the proximity method, the number of candidate channels (channels with less interference) is likely to be larger than that in the normal method. Therefore, the wireless communication apparatus according to the present embodiment can reduce the time required to select the channel on which the proximity BSS operates by using the same carrier sense level as in the first embodiment.

  Next, a reduction in the time required to search for a proximity BSS will be described. Such time depends on the maximum length of the Beacon Interval that may be used in the BSS. Therefore, the wireless communication apparatus according to the present embodiment limits the maximum length of the beacon interval in the proximity method to be shorter than that in the normal method. For example, the wireless communication apparatus sets the maximum length of the Beacon Interval in the normal method to 1 s and sets the maximum length of the Beacon Interval in the proximity method to 10 ms. According to this setting, when the wireless communication device searches for a proximity BSS in a specific frequency channel by passive scanning, the search may be continued for 10 ms. On the other hand, when the wireless communication device searches for a normal BSS in a specific frequency channel by passive scanning, it is necessary to continue the search for 1 s. Therefore, the time required for passive scanning in the proximity method can be shortened compared to the normal method.

  On the other hand, with regard to active scanning, a procedure in which wireless communication apparatuses using the millimeter wave band transmit Beacon frames to each other to adjust the antenna directivity angle may be performed. If the beacon interval in this procedure is selected at random from a range less than or equal to the maximum length of the beacon interval, the effect of limiting the maximum beacon interval in the proximity method to be shorter than that in the normal method can be obtained. That is, the time required for active scanning in the proximity method may be shortened compared to the normal method.

  Next, shortening of the time for negotiation when a wireless communication apparatus that periodically transmits a Beacon frame collides will be described. For example, it is assumed that each of two wireless communication apparatuses has started an application using a proximity method and is in the process of forming a proximity-type BSS. One wireless communication device (referred to as a first wireless communication device for convenience in this embodiment) is ahead of the other (referred to as a second wireless communication device for convenience in this embodiment). The Beacon frame is transmitted periodically. However, the second wireless communication apparatus periodically transmits a Beacon frame due to a request from an application (for example, a user wants to set the length of the Beacon Interval to a desired value, or wants to manage a schedule in the Beacon Interval). Wants to be a wireless communication device (also called group owner).

  In such a situation, in general, the second wireless communication apparatus transmits a request to acquire the right to transmit a Beacon frame (to become a group owner) to the first wireless communication apparatus. Then, it is negotiated between the first wireless communication apparatus and the second wireless communication apparatus which one acquires the transmission right of the Beacon frame (becomes the group owner). Conventionally, this negotiation is realized by exchanging management frames. Specifically, the request level of the wireless communication device on the transmission side is displayed in each of the two frames exchanged first by the wireless communication devices. Then, the wireless communication device having a higher request level acquires the transmission right of the Beacon frame (becomes a group owner). Therefore, such negotiation requires three frames: two frames for notifying each other's request level and one frame for notifying the final decision (transfer / no transfer). Further, according to such negotiation, it is difficult to uniquely determine which wireless communication device acquires the right to transmit a Beacon frame when both request levels are the same. Furthermore, the wireless communication apparatus cannot recognize the request level of the communication partner until the negotiation frame is exchanged.

  Therefore, if the request level of the wireless communication device according to the present embodiment is the same as the request level of the communication partner, the wireless communication device refers to an identifier (for example, a MAC address) unique to the wireless communication device. Specifically, the wireless communication apparatus compares its own identifier with the identifier of the communication partner, and determines that the one with the larger value (or may be smaller) acquires the transmission right for the Beacon frame.

  It is also effective for the first wireless communication apparatus to describe its own request level in the frame body field of the Beacon frame. According to this technique, the second wireless communication apparatus can recognize the request level of the first wireless communication apparatus when receiving the Beacon frame from the first wireless communication apparatus. Accordingly, the second wireless communication device compares its own request level with the request level of the first wireless communication device, and transmits a request frame for starting negotiation to the first wireless communication device if its own request level is high. If the request level of the first wireless communication apparatus is high, the transmission right of the Beacon frame may be transferred to the first wireless communication apparatus.

  In general, the MAC address of the transmission source wireless communication device (in this example, the first wireless communication device) is described as a wireless communication group identifier (BSSID) in the Beacon frame. Therefore, the MAC address of the first wireless communication apparatus can be referred to through the received Beacon frame as with the request level. If the request level of the second wireless communication device is the same as the request level of the first wireless communication device, the second wireless communication device compares the MAC address of the first wireless communication device with the MAC address of the first wireless communication device. If the address is large, the negotiation start request frame may be transmitted to the first wireless communication apparatus. If the MAC address of the first wireless communication apparatus is large, the right to transmit the Beacon frame is transferred to the first wireless communication apparatus. That's fine.

  Therefore, by describing the request level of the first radio communication device in the frame body field of the Beacon frame, the second radio communication device can recognize the request level of the first radio communication device before starting the negotiation. Therefore, useless frame exchange in the negotiation is omitted. In other words, since the second wireless communication apparatus can recognize in advance whether or not the transmission right of the Beacon frame can be acquired, if the transmission right of the Beacon frame cannot be acquired, the request frame is transmitted to the first wireless communication apparatus. Do not send. On the other hand, when the second wireless communication device can acquire the transmission right of the Beacon frame, the second wireless communication device transmits a request frame to the first wireless communication device, but the first wireless communication device returns a response frame that acknowledges this. The negotiation is completed in a total of two frames. That is, the time for negotiation in the proximity method is shorter than that in the normal method. The same effect can be obtained even if the required level is described in the frame body field of the Probe Response frame instead of the Beacon frame.

  When both the request levels are the same, it is possible to compare parameters other than an identifier (for example, a MAC address) unique to the wireless communication device. For example, the wireless communication device may compare timer values. Specifically, since the Beacon frame is used to synchronize other wireless communication apparatuses, a timer value held by the transmission source is described therein. In IEEE 802.11, a timer value held by the transmission source of the Beacon frame is described in the Timestamp field. In general, when the wireless communication device decides to participate in the BSS (ie, the MAC / PHY management unit 70 outputs MLME-JOIN.request to the MAC common processing unit 15), the reception processing unit 20 The MAC common processing unit 15 matches (synchronizes) its timer value with the Timestamp value of the received Beacon frame.

  The operation when comparing timer values will be described below. When the MAC / PHY management unit 70 determines the BSS to participate in, if it is desired to acquire the transmission right of the BSS Beacon frame (become the group owner), the request level is compared as described above. . When the request level described in the received Beacon frame is lower than its own request level, the MAC / PHY management unit 70 instructs the MAC common processing unit 15 to transmit a request frame for starting negotiation. If the request level is lower than the request level described in the received Beacon frame, the MAC / PHY management unit 70 does not give an instruction to transmit a request frame for starting negotiation, and performs MLME-JOIN. The request is output to the MAC common processing unit 15. Further, even when the request level of itself is the same as the request level described in the received Beacon frame, the MAC / PHY management unit 70 instructs the MAC common processing unit 15 to transmit a request frame for starting negotiation. The MAC common processing unit 15 compares the timer values before transmitting the request frame. Specifically, the MAC common processing unit 15 compares its own timer value with the Timestamp value of the received Beacon frame, and transmits the request frame as instructed if its own timer value is large. On the other hand, if the Timestamp value of the received Beacon frame is large, the MAC common processing unit 15 synchronizes its timer value with the Timestamp value, and synchronizes with the MAC / PHY management unit 70 (that is, the request level is the same as the communication partner). The timer value is smaller than that of the communication partner). In some cases, both timer values may be the same. In such a case, the MAC common processing unit 15 may randomly determine whether or not the MAC common processing unit 15 acquires the transmission right of the Beacon frame, for example, by rolling a dice having only 1 or 0 eyes. In any case, when a request frame is transmitted, the negotiation is completed in a total of two frames as in the above example.

  According to the above method, in the proximity method, it is possible to omit useless frame exchange regarding negotiation for the transmission right of the Beacon frame and to reduce the number of frames exchanged in the negotiation. Therefore, the time required for negotiation can be shortened.

  As described above, regarding the management frame exchange, it is also effective to set the time for waiting for reception of the next management frame after transmitting the management frame in the proximity method to be shorter than that in the normal method. According to such control, the time required to complete the frame exchange can be shortened. For example, as described in the third embodiment, the MAC / PHY management unit 70 designates a time for waiting for an association response, and MLME-ASSOCATION. The MAC common processing unit 15 can be notified through a request primitive. Therefore, when the proximity method is selected (dot11 Close Proximity Communication Enable is set to TRUE), the MAC / PHY management unit 70 may designate a shorter time than the normal method. It should be noted that the same effect can be obtained by the same method for exchanging other management frames. That is, in the proximity method, the time that the MAC / PHY management unit 70 waits for the management frame is specified to be shorter than that in the normal method, and MLME-ASSOCATION. The MAC common processing unit 15 can be notified through a request primitive.

  As described above, the wireless communication apparatus according to the fifth embodiment reduces the time required to start exchanging data frames in the proximity method compared to the normal method. Therefore, according to the wireless communication apparatus according to the present embodiment, since the setup time of the communication link is shortened, the proximity wireless communication suitable for the use case assumed for the proximity method can be realized.

(Sixth embodiment)
The wireless communication apparatus according to the sixth embodiment is a part of the wireless communication apparatus according to the first to fifth embodiments described above. Specifically, the wireless communication apparatus according to the present embodiment sets the transmission power and the antenna gain when operating in the normal mode in the same manner as that when operating in the proximity mode.

  In the wireless communication apparatus according to the present embodiment, the value of the attribute dot11CloseProximityCommunicationImplemented is assumed to be TRUE. For example, the wireless communication apparatus sets 10 dBm as the maximum transmission power in the normal method according to the above-described example, but sets 0 dBm as the maximum transmission power in the proximity method as the default value.

  Furthermore, if the wireless communication apparatus does not change the antenna gain used until the connection link is established in the proximity method and the antenna gain used when exchanging data frames, the antenna gain in the normal method should not be basically changed. And

  As described above, the radio communication apparatus according to the sixth embodiment basically limits the difference when operating in the normal method and the proximity method to the carrier sense level. Therefore, according to the wireless communication apparatus according to the present embodiment, the processing load due to the change of the communication method is reduced compared to the other embodiments. In addition, since the default behavior in the normal method is similar to that in the proximity method, the reception condition in the normal method is similar to the reception condition in the proximity method, and it is easy to find a communication partner that satisfies the reception condition in the proximity method. As a result, the opportunity for the wireless communication apparatus to select the proximity method increases, and the use opportunity of the proximity application increases.

(Seventh embodiment)
The wireless communication apparatus according to the seventh embodiment supplements the wireless communication apparatuses according to the first to sixth embodiments described above. Specifically, the wireless communication apparatus according to the present embodiment sets the contention parameter in the proximity method to a more appropriate value.

  IEEE802.11 is a wireless communication system based on carrier sense as described above, and more specifically, CSMA / CA (Carrier Sense Multiple Access with Collaboration Avidance) is employed. Hereinafter, CSMA / CA will be briefly described. For example, according to a simple mechanism in which a signal is transmitted if it is determined that the medium has become idle after performing carrier sense, when a plurality of wireless communication devices are waiting for a medium to be idle, a signal is transmitted at the same timing and a collision occurs. May occur. Therefore, according to CSMA / CA, each wireless communication device randomly selects a value from a value within a predetermined range (referred to as a contention window), and waits according to the selected value before transmitting a signal.

  According to the normal method, when data is transferred from an upper layer with respect to a data frame, the priority of the data (User Priority (referred to as UP) in IEEE802.11) is indicated. Further, a priority for accessing the medium (Access Category (referred to as AC in IEEE 802.11)) is assigned based on the priority of the data. The data frame is transmitted according to the contention parameter determined for each priority for accessing the medium. The contention parameter includes, for example, a minimum value and a maximum value of the contention window (referred to as CWmin and CWmax in IEEE 802.11, respectively), a frame interval to wait before starting to count down the selected random number (in IEEE 802.11, It is converted in a unit called a slot and is called AIFSN), a maximum transmission right acquisition time (called TXOP limit in IEEE 802.11), and the like.

  In general, it is assumed that the proximity method has fewer competing wireless communication devices than the normal method, and it is often sufficient that one-to-one communication can be realized. Therefore, even if the proximity method uses a contention window narrower than that of the normal method, it is possible to sufficiently avoid the competition. On the contrary, if the contention window is set to be as wide as the normal method, the wireless communication device has a high probability of waiting inappropriately for a long time and the transmission of the signal is delayed according to the waiting time, so the medium is idle idle. It takes a long time to become inefficient. Therefore, the wireless communication apparatus according to the present embodiment is set so that the contention window width in the proximity method is narrower than that in the normal method. For example, the wireless communication apparatus sets a CWmax value for each AC smaller than that in the normal method. Of course, the wireless communication apparatus may set other parameters for the proximity method. Alternatively, in the normal method, a parameter set is prepared for each AC, but in the proximity method, the wireless communication apparatus has only one parameter set including the smallest CWmax in the normal method (a parameter set defined for AC_VO in IEEE 802.11). May be used.

  When these contention parameter values are redefined for the proximity method separately from the normal method, the contention parameter set for the proximity method is retained in the MIB as, for example, dot11CPCATable as in the other embodiments described above. That's fine. Similarly, if it is desirable to redefine other parameters used in the normal method for the proximity method, the entire redefined parameter is retained in the MIB as a proximity parameter set (for example, dot11CloseProximityParameterTable). Also good.

  As described above, the wireless communication apparatus according to the seventh embodiment redefines the contention parameter for the proximity method. Therefore, according to the wireless communication apparatus according to the present embodiment, efficient CSMA / CA can be realized in the proximity method.

(Eighth embodiment)
The wireless communication apparatus according to the eighth embodiment supplements the wireless communication apparatuses according to the first to seventh embodiments described above. Specifically, this embodiment describes an operation when wireless communication apparatuses connected in the proximity method are separated beyond the communication range.

  In general, the normal method is designed in accordance with a policy of maintaining a connection when a reception state of a signal from a communication partner is deteriorated or cannot be received. On the other hand, the proximity method may require that communication be started when wireless communication devices are close to the communication range or less, and that the connection be automatically disconnected when both devices exceed the communication range. unknown.

  Therefore, in the proximity method, if the wireless communication device according to the present embodiment does not receive a frame for a certain period from the communication partner that has once started exchanging data frames, the wireless communication device assumes that the communication partner is gone and Delete information about connection status. This fixed period is determined by, for example, MIB. For example, the MAC common processing unit 15 monitors the reception status of the frame from the communication partner while referring to the predetermined period. Further, the MAC common processing unit 15 holds a management table for managing information related to other wireless communication devices permitted to associate. Then, when the MAC common processing unit 15 considers that there is no wireless communication device as a communication partner, the MAC common processing unit 15 deletes information related to the connection state with the wireless communication device from the management table. Further, if the transmission period for the wireless communication apparatus is scheduled in the Beacon Interval, the MAC common processing unit 15 also deletes the scheduled transmission period.

  In the proximity method, the wireless communication device according to the eighth embodiment assumes that there is no communication partner if it does not receive a frame for a certain period from the communication partner that has once started exchanging data frames. Delete information about connection status. Therefore, according to the wireless communication device according to the present embodiment, in the proximity method, the connection can be automatically disconnected when the wireless communication device of the communication partner is separated beyond the communication range.

  Note that the wireless communication apparatus according to this embodiment uses a higher carrier sense level for the proximity method than the normal method for the proximity method, as in the first embodiment described above, so that a receivable MAC frame can be transmitted using the proximity method. It is limited to what is transmitted within the range. Therefore, when the wireless communication device of the communication partner is separated beyond the communication range, the MAC frame transmitted from the wireless communication device is not passed to the MAC processing unit 10, and thus a situation occurs in which the frame is not received for a certain period. .

(Ninth embodiment)
In the ninth embodiment, a buffer is provided in addition to the configuration of the wireless communication apparatus of FIG. 1, FIG. 3, or FIG. As described above, by including the buffer in the wireless communication apparatus, it is possible to hold the transmission / reception frame in the buffer, and it is possible to easily perform the retransmission process and the external output process.

(Tenth embodiment)
In the tenth embodiment, in addition to the configuration of the wireless communication apparatus according to the ninth embodiment, a bus, a processor unit, and an external interface unit are provided. The processor unit and the external interface unit are connected to the buffer via the bus. Firmware operates in the processor unit. As described above, by configuring the firmware to be included in the wireless communication device, it is possible to easily change the function of the wireless communication device by rewriting the firmware.

(Eleventh embodiment)
In the eleventh embodiment, a clock generation unit is provided in addition to the configuration of the wireless communication apparatus of FIG. 1, FIG. 3, or FIG. The clock generation unit generates a clock and outputs the clock from the output terminal to the outside of the wireless communication device. Thus, the host side and the wireless communication apparatus side can be operated in synchronization by outputting the clock generated inside the wireless communication apparatus to the outside and operating the host side with the clock output to the outside. It becomes possible.

(Twelfth embodiment)
The twelfth embodiment includes a power supply unit, a power supply control unit, and a wireless power supply unit in addition to the configuration of the wireless communication apparatus of FIG. 1, FIG. 3, or FIG. The power supply control unit is connected to the power supply unit and the wireless power supply unit, and performs control to select a power supply to be supplied to the wireless communication device. As described above, by providing the wireless communication apparatus with the power supply, it is possible to perform a low power consumption operation by controlling the power supply.

(13th Embodiment)
The thirteenth embodiment includes a SIM card in addition to the configuration of the wireless communication apparatus according to the twelfth embodiment. The SIM card is connected to the MAC processing unit 10 or the MAC / PHY management unit 70. As described above, by adopting a configuration in which the SIM card is provided in the wireless communication device, authentication processing can be easily performed.

(Fourteenth embodiment)
In the fourteenth embodiment, a moving image compression / decompression unit is included in addition to the configuration of the wireless communication apparatus according to the tenth embodiment. The moving image compression / decompression unit is connected to the bus. As described above, by providing the wireless communication device with the moving image compression / decompression unit, it is possible to easily transmit the compressed moving image and expand the received compressed moving image.

(Fifteenth embodiment)
In the fifteenth embodiment, an LED unit is included in addition to the configuration of the wireless communication apparatus of FIG. 1, FIG. 3, or FIG. The LED unit is connected to the MAC processing unit 10 or the PHY processing unit 40. In this way, by providing the wireless communication device with the LED unit, it is possible to easily notify the user of the operating state of the wireless communication device.

(Sixteenth embodiment)
In the sixteenth embodiment, a vibrator unit is included in addition to the configuration of the wireless communication apparatus of FIG. 1, FIG. 3, or FIG. The vibrator unit is connected to the MAC processing unit 10 or the PHY processing unit 40. As described above, by providing the radio communication device with the vibrator unit, it is possible to easily notify the user of the operation state of the radio communication device.

(Seventeenth embodiment)
In the seventeenth embodiment, a plurality of different PHY processing units 40 are provided as described in the first embodiment in addition to the configuration of the wireless communication apparatus of FIG. 1, FIG. 3, or FIG. including. The radio switching unit is connected to a plurality of different PHY processing units 40 and switches between communication by the different PHY processing units 40. As described above, by providing the wireless communication apparatus with a plurality of different PHY processing units 40, it is possible to switch to communication using an appropriate PHY processing unit 40 according to the situation.

(Eighteenth embodiment)
In the eighteenth embodiment, in addition to the configuration of the wireless communication apparatus of FIG. 1, FIG. 3, or FIG. 4, as described in the first embodiment, a plurality of different PHY processing units 40 are provided. A pair of reception processing unit 20 and transmission processing unit 30 corresponding to the PHY processing unit 40 is provided, and includes a wireless switching unit. The wireless switching unit is connected so that the paired reception processing unit 20 and transmission processing unit 30 can be switched, and switches between a plurality of communication schemes by different reception processing units 20, transmission processing unit 30 and PHY processing unit 40. As described above, the wireless communication device includes a set of a plurality of different reception processing units 20, transmission processing units 30, and PHY processing units 40, so that an appropriate reception processing unit 20 and transmission processing unit 30 depending on the situation. And it becomes possible to switch to the communication using the set of the PHY processing unit 40.

(Nineteenth embodiment)
In the nineteenth embodiment, in addition to the configuration of the wireless communication apparatus according to the seventeenth embodiment, a switch (SW) is included. The switch is connected to the antenna 60, a plurality of different PHY processing units 40, and a wireless switching unit. As described above, by providing the switch in the wireless communication device, it is possible to switch to communication using the appropriate PHY processing unit 40 according to the situation while sharing the antenna.

(20th embodiment)
The twentieth embodiment includes a switch (SW) in addition to the configuration of the wireless communication apparatus according to the eighteenth embodiment. The switch is connected to the antenna 60, the base of the paired reception processing unit 20 and the transmission processing unit 30, and the radio switching unit. In this way, by adopting a configuration in which the switch is provided in the wireless communication device, switching to communication using a set of the appropriate reception processing unit 20, transmission processing unit 30, and PHY processing unit 40 according to the situation while sharing the antenna. It becomes possible.

  The processing of each of the above embodiments can be realized by using a general-purpose computer as basic hardware. The program for realizing the processing of each of the above embodiments may be provided by being stored in a computer-readable storage medium. The program is stored in the storage medium as an installable file or an executable file. The storage medium may be a computer-readable storage medium such as a magnetic disk, optical disk (CD-ROM, CD-R, DVD, etc.), magneto-optical disk (MO, etc.), semiconductor memory, etc. Any of them may be used. Further, the program for realizing the processing of each of the above embodiments may be stored on a computer (server) connected to a network such as the Internet and downloaded to the computer (client) via the network.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... MAC processing part 15 ... MAC common processing part 20 ... Reception processing part 30 ... Transmission processing part 40 ... PHY processing part 50 ... Frequency conversion circuit 60 ... Antenna 70 ..MAC / PHY management unit 100 ... host processing unit

Claims (17)

In a wireless communication apparatus that supports a first wireless communication scheme that uses a first set of modulation and coding schemes and a second wireless communication scheme that uses a second set of modulation and coding schemes,
A first processing unit for setting a maximum transmission power and a carrier sense level;
A second processing unit for performing carrier sense using the carrier sense level;
A third processing unit that controls transmission / reception of frames via the second processing unit;
Comprising
The second set of modulation and coding schemes is the same as part of the first set of modulation and coding schemes;
Each of the second set of modulation and coding schemes is defined with a minimum reception sensitivity common to a corresponding one of the first set of modulation and coding schemes;
When the second wireless communication method is used, the first processing unit has a second higher than the lowest first level among the minimum reception sensitivities of the second set of modulation and coding methods. Set the carrier sense level to a level, set a second power value lower than the first power value to the maximum transmission power,
The third processing unit controls exchange of data frames using the second wireless communication method in a wireless communication group whose attribute is the second wireless communication method;
Wireless communication device. An information management base holding an attribute indicating whether or not to operate in the second wireless communication system;
It is determined whether or not the second wireless communication method is used based on an attribute indicating whether or not to operate in the second wireless communication method.
The wireless communication apparatus according to claim 1. When the attribute indicating whether or not to operate in the second wireless communication method is a value of FALSE, the first wireless communication method is used,
When the first wireless communication scheme is used, the first processing unit sets the first power value to the maximum transmission power, and the minimum reception of the first set of modulation and coding schemes. Setting the lowest third level of sensitivity to the carrier sense level;
The wireless communication apparatus according to claim 2. When the wireless communication device participates in a wireless communication group whose attribute is the second wireless communication method, the attribute indicating whether or not to operate in the second wireless communication method is rewritten to a value of TRUE. The wireless communication apparatus according to claim 2. When the wireless communication device participates in a wireless communication group whose attribute is the second wireless communication method, data frame exchange using the second wireless communication method starts after an association process. Item 4. The wireless communication device according to Item 4. The wireless communication device according to claim 5, wherein the Association Request frame stores information based on an attribute value indicating whether or not to operate in the second wireless communication method. The information management base holds an attribute indicating whether or not the second wireless communication system is supported, and determines whether or not to operate in the second wireless communication system when the attribute is a value of TRUE. The wireless communication apparatus according to claim 2, further comprising an attribute to be indicated. The wireless communication apparatus according to claim 7, wherein a default value of an attribute indicating whether or not to operate in the second wireless communication system is FALSE. When the wireless communication device forms a wireless communication group based on the second wireless communication method, the management frame stores information indicating that the attribute of the wireless communication group is the second wireless communication method. Item 2. The wireless communication device according to Item 1. The wireless communication apparatus according to claim 9, wherein the management frame is at least one of a Beacon frame and a Probe Response frame. When the wireless communication device forms a wireless communication group based on the second wireless communication method, the second wireless communication device is associated with the second wireless communication device after undergoing an association process with the other wireless communication device. The wireless communication apparatus according to claim 9, wherein data frame exchange using a wireless communication system starts. If the association request frame from the other wireless communication device does not store information indicating that the other wireless communication device operates in the second wireless communication method, the wireless communication device transmits an association response frame. The wireless communication apparatus according to claim 11, wherein the association is rejected via the wireless communication apparatus. If the Association Request frame from the other wireless communication device does not store information indicating that the other wireless communication device operates in the second wireless communication method, the wireless communication device is in an Association Response frame. The wireless communication apparatus according to claim 12, wherein the reason code is added because the reason is "because it does not operate in the second wireless communication system". When the wireless communication device forms a wireless communication group based on the second wireless communication method, a modulation code essential for reception in the wireless communication group in the field indicating the attribute of the wireless communication group in the management frame The radio communication apparatus according to claim 9, wherein a code that does not actually indicate a modulation and coding scheme is defined as a coding scheme. The first set of modulation and coding schemes includes a first physical modulation and coding scheme and a second physical and modulation coding scheme;
The second set of modulation and coding schemes does not include the modulation and coding scheme of the first physical scheme but includes the modulation and coding scheme of the second physical scheme;
The lowest third level among the minimum reception sensitivities of the first set of modulation and coding schemes matches the minimum reception sensitivity of one of the modulation and coding schemes of the first physical scheme.
The wireless communication apparatus according to claim 1. The wireless communication apparatus according to claim 1, further comprising an antenna that transmits and receives the frame. In a wireless communication method performed by a wireless communication apparatus that supports a first wireless communication scheme using a first set of modulation and coding schemes and a second wireless communication scheme using a second set of modulation and coding schemes,
The first processing unit sets a maximum transmission power and a carrier sense level;
A second processing unit performs carrier sense using the carrier sense level;
A third processing unit controlling transmission / reception of a frame via the second processing unit;
Comprising
The second set of modulation and coding schemes is the same as part of the first set of modulation and coding schemes;
Each of the second set of modulation and coding schemes is defined with a minimum reception sensitivity common to a corresponding one of the first set of modulation and coding schemes;
When the second wireless communication method is used, the first processing unit has a second higher than the lowest first level among the minimum reception sensitivities of the second set of modulation and coding methods. Set the carrier sense level to a level, set a second power value lower than the first power value to the maximum transmission power,
The third processing unit controls exchange of data frames using the second wireless communication method in a wireless communication group whose attribute is the second wireless communication method;
Wireless communication method.

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