JP6874074B2 - Wireless communication device and wireless communication method - Google Patents

Description

Embodiments of the present invention relate to wireless communication devices and wireless communication methods.

As a wireless communication system that communicates between a wireless access point and a wireless terminal, a wireless LAN (Local Area Network) that employs CSMA / CA (Carrier Sense Multiple Access / Collision Availability) is widely known. In the IEEE802.11ac standard, DL-MU-MIMO (DL-MU-MIMO) technology, which is an extension of MIMO (Multi-Input Multi-Autoput) technology, is adopted. In DL-MU-MIMO, the access point uses a technique called beamforming, which enables data transmission by beams that are spatially orthogonal to each wireless terminal. Therefore, for multiple wireless terminals, Separate data can be sent at the same time. As a result, the system throughput can be improved.

In addition, with the aim of further improving efficiency, the task group of IEEE802.11ax, which is the successor to the IEEE802.11ac standard, is studying technologies aimed at improving efficiency.
One of the candidate technologies is the uplink multi-user MIMO (UL-MU-MIMO) technology. In UL-MU-MIMO, it is possible to improve the efficiency of uplink transmission by transmitting data to an access point by a plurality of wireless terminals using spatially orthogonal beams at the same timing.

In order to fully obtain the effect of spatial multiplexing by multi-user MIMO, it is desirable to keep the number of user multiplexing above a certain level even when retransmitting data. For example, it is assumed that spatial multiplex transmission of four wireless terminals is performed at the time of new transmission, and a CRC (Cyclic Redundancy Check) error occurs in only one of the data. In this case, if only the data is retransmitted, user multiplexing will not be performed as a result, and the system throughput will decrease.

As a method for solving this problem, it is known that when the access point retransmits during DL-MU-MIMO transmission, the utilization efficiency is improved by newly multiplexing new data in addition to the retransmitted data. ing. As a result, it is possible to maintain a certain number of users or more even at the time of retransmission. Therefore, even when retransmission occurs, it is possible to improve the system throughput by spatial multiplexing.

However, this method is specific to DL-MU-MIMO and does not consider UL-MU-MIMO. That is, in the case of DL-MU-MIMO transmission, the access point transmits a combination of retransmission data and new data at the judgment of the access point based on the delivery confirmation response result returned from each wireless terminal. Can be done. On the other hand, in the case of UL-MU-MIMO transmission, each wireless terminal is the transmitting side of the multi-user MIMO, and there are a plurality of transmitting terminals. Therefore, the wireless terminal that wants to transmit the new data cannot determine whether the new data may be multiplexed and transmitted at the same time as the wireless terminal that transmits the retransmission data. Further, in UL-MU-MIMO, there is no mechanism capable of multiplexing and transmitting retransmission data and new data by a plurality of wireless terminals. Therefore, when data is retransmitted, highly efficient UL-MU-MIMO transmission that maintains a certain number of user multiplex cannot be realized. In addition to MU-MIMO, the user multiplex transmission method includes the orthogonal frequency division multiple access method (Orthogonal Frequency Division Multiple).
Access) is known, and the same problem as described above may occur when the retransmission data and the new data are simultaneously transmitted from a plurality of wireless terminals by the uplink OFDMA (UL-OFDMA). In UL-OFDMA, a resource unit including one or a plurality of subcarriers is used as a minimum unit communication resource, and reception from a plurality of wireless terminals is performed at the same time.

Japanese Unexamined Patent Publication No. 2010-28284

IEEE Std 802.11acTM-2013 IEEE Std 802.11TM-2012 IEEE 802.11-15 / 0831r2

An embodiment of the present invention has been made in consideration of the above problems, and an object of the present invention is to suppress a decrease in system throughput even when a wireless terminal that requires retransmission occurs.

The wireless communication device according to the embodiment of the present invention includes a receiving unit that receives a plurality of first frames to be multiplex-transmitted, an inspection result as to whether or not each of the plurality of first frames has been successfully received, and at least one. A transmission unit that transmits a second frame including a first information that specifies a wireless communication device is provided, and the reception unit is a plurality of third frames that are multiplex-transmitted in response to the second frame. To receive.

The figure which shows the wireless communication system which concerns on 1st Embodiment. The figure explaining the outline of UL-MU-MIMO transmission which concerns on 1st Embodiment. The figure which shows the example of the format of the trigger frame which concerns on 1st Embodiment. The figure which shows another example of the format of a trigger frame. The figure which shows the example of the format of the usual delivery confirmation response frame which concerns on 1st Embodiment. The figure which shows the example of the format of the delivery confirmation response frame with a notification function which concerns on 1st Embodiment. The functional block diagram of the wireless communication apparatus mounted on the access point which concerns on 1st Embodiment. The functional block diagram of the wireless communication apparatus mounted on the wireless terminal which concerns on 1st Embodiment. The flowchart of the operation of the access point which concerns on 1st Embodiment. The flowchart of the operation of the wireless terminal which concerns on 1st Embodiment. The figure which shows the example of the plurality of resource units reserved in the continuous frequency domain in one channel. The figure which shows the sequence example of the operation which concerns on 2nd Embodiment. The figure which shows the sequence example of the other operation which concerns on 2nd Embodiment. The figure which shows the sequence example of the other operation which concerns on 2nd Embodiment. The figure which shows the sequence example of the operation which concerns on 3rd Embodiment. The figure which shows typically the structure of the aggregation frame. The figure which shows the structural example of the Block Acck frame. The figure which shows the example of the frame transmission which concerns on 3rd Embodiment. The figure which shows another example of frame transmission which concerns on 3rd Embodiment. The figure which shows another example of frame transmission which concerns on 3rd Embodiment. The figure which shows another example of frame transmission which concerns on 3rd Embodiment. The figure which shows another example of frame transmission which concerns on 3rd Embodiment. The functional block diagram of the access point or the terminal which concerns on 4th Embodiment. The figure which shows the whole configuration example of a terminal or an access point. The figure which shows the hardware configuration example of the wireless communication apparatus mounted on the access point or the wireless terminal which concerns on 5th Embodiment. The perspective view of the wireless terminal which concerns on 6th Embodiment. The figure which shows the memory card which concerns on 6th Embodiment. The figure which shows an example of frame exchange of a contention period.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. IEEE Std ^802.11 TM -2012 and IEEE Std 802.11ac ^TM -2013 has been known as the specifications of the wireless LAN, IEEE 802.11-15 / 0132r7 dated on July 20, 2015 which is Specification Framework Document directed to IEEE Std 802.11 All of the ax as a next generation wireless LAN standards are incorporated herein by reference.

(First Embodiment)
FIG. 1 shows a wireless communication system according to the first embodiment.

The wireless communication system of FIG. 1 is a wireless network including an access point (AP) 11 and a plurality of wireless terminals (stations) 1, 2, 3, 4, 5, and 6. The access point 11 is also a form of a wireless terminal because it has the same functions as the wireless terminal except that it has a relay function. The access point 11 communicates with each of the wireless terminals 1 to 6 according to an arbitrary wireless communication method such as the IEEE802.11 standard. In this embodiment, the access point 11 and the wireless terminals 1 to 6 communicate with each other according to the IEEE 802.11 standard. The access point 11 establishes a wireless link with each of the wireless terminals 1 to 6 via a predetermined association process or the like. The wireless communication method applicable to this embodiment is not limited to the IEEE802.11 standard, and any other wireless communication method may be used as long as it is a wireless communication method capable of multiplex transmission by an uplink user.

The access point 11 includes four antennas 12A, 12B, 12C, and 12D as a plurality of antennas. The access point 11 is equipped with a wireless communication device (see FIG. 7 described later) that communicates with the wireless terminal. The wireless communication device includes a wireless communication unit connected to the antennas 12A to 12D to transmit and receive frames, and a control unit that controls communication with a plurality of wireless terminals. The wireless communication unit is formed by an RF (Radio Frequency) integrated circuit as an example, and is formed by a control unit and a baseband integrated circuit as an example, but is not limited to this configuration.

Each wireless terminal 1 to 6 includes one or more antennas, respectively. In the example of FIG. 1, each wireless terminal 1 to 6 includes one antenna 1A, 2A, 3A, 4A, 5A, and 6A, respectively. Each wireless terminal is equipped with a wireless communication device (see FIG. 8 described later) that communicates with the access point. The wireless communication device includes a wireless communication unit connected to an antenna to transmit and receive frames, and a control unit that controls communication with the access point 11. The wireless communication unit is formed by an RF (Radio Frequency) integrated circuit as an example, and is formed by a control unit and a baseband integrated circuit as an example, but is not limited to this configuration.

The access point 11 forms a wireless network (referred to as a first network) with each wireless terminal. In addition, the access point 11 may be separately connected to another network (referred to as a second network) of wired or wireless or a hybrid thereof. The access point 11 relays communication between the first network and the second network, and relays communication between wireless terminals in the first network. The data frames generated by the wireless terminals 1 to 6 are transmitted to the access point 11, and the access point 11 transfers the data frames to another wireless terminal of the first network or a second network. The frame of the present embodiment may be, for example, not only a frame called a frame in the IEEE802.11 standard, but also a packet (Null Data Packet, etc.).

In the present embodiment, an uplink user multiplexing method can be used as one of the methods for transmitting the data frame generated by each wireless terminal to the access point 11. For user multiplex transmission, a multi-user MIMO (MU-MIMO: Uplink Multi-User-MIMO (Multi-Input Multi-Auto)) method using spatial multiplexing and an orthogonal frequency division multiplex connection method (Orthogonal) using frequency multiplexing are used.
There is Frequency Division Multiple Access).
In particular, uplink MU-MIMO is described as UL-MU-MIMO, and downlink MU-MIMO is described as DL-MU-MIMO. The uplink OFDMA is described as UL-OFDMA, and the downlink OFDMA is described as DL-OFDMA.

In UL-MU-MIMO transmission, a plurality of wireless terminals simultaneously transmit a plurality of frames as a plurality of data streams in the same frequency band. Specifically, a plurality of wireless terminals (for example, wireless terminals 1 to 4) among the wireless terminals 1 to 6 simultaneously transmit a data frame addressed to the access point 11. The access point 11 can separate and receive frames for each terminal by separating these data streams based on the uplink propagation path response with each terminal. With UL-MU-MIMO, a plurality of wireless terminals can transmit data frames at the same time, so that throughput can be improved.

The number of data streams that can be transmitted by UL-MU-MIMO is limited by the number of antennas included in the access point 11, and is the maximum number of antennas included in the access point 11. In FIG. 1, since the access point 11 includes four antennas, the number of data streams capable of uplink transmission at the same time is four. If the terminal is equipped with a plurality of antennas, the terminal can also transmit a plurality of data streams. For example, one terminal may transmit two data streams, and two terminals may each transmit one data stream. The combination of wireless terminals that perform UL-MU-MIMO transmission is not limited to wireless terminals 1 to 4, and various combinations are possible from wireless terminals 1 to 6. In addition to the wireless terminals 1 to 6, in FIG. 1, there may be other wireless terminals that have established a wireless link with the access point 11.

In order for a plurality of wireless terminals to perform UL-MU-MIMO transmission, it is necessary to match the transmission timings of these wireless terminals. Therefore, as an example, a trigger frame including information (permitted terminal information) that identifies a wireless terminal that instructs or permits UL-MU-MIMO transmission (hereinafter, unified into permission) is transmitted. The permitted terminal information may be in any format as long as the wireless terminal group that permits UL-MU-MIMO transmission can be specified. As an example, the permitted terminal information may be the identification information of each permitted wireless terminal, or may be the identification information of a group including a plurality of permitted wireless terminals. The trigger frame may include various information (for example, preamble information described later) necessary for performing UL-MU-MIMO transmission in addition to the permitted terminal information.
In the present embodiment, one trigger frame serves both the notification of the permitted terminal information and the adjustment of the transmission timing, but there may be a configuration in which these frames are transmitted separately.

In order to perform UL-MU-MIMO transmission, the access point 11 first selects a plurality of wireless terminals that allow UL-MU-MIMO transmission. Any method may be used for selecting the wireless terminal. For example, a method of selecting from wireless terminals for which transmission requests have been made in advance, a method of selecting from wireless terminals for which a wireless link has been established, and the like by round-robin can be considered.

The access point 11 generates a trigger frame including the permitted terminal information that specifies the selected wireless terminal, and transmits the trigger frame from any one antenna or simultaneously from a plurality of antennas. The recipient address (Receiver Address) of the trigger frame is, for example, a broadcast address or a multicast. The Type of the Frame Control field of the trigger frame 71 is Control, and the Subtype may be a newly defined value for the trigger frame. Alternatively, Type and Subtype may use existing values and set reserved fields of existing frames and information for notifying that they are trigger frames.

Before transmitting the trigger frame, the access point 11 performs a carrier sense between a certain period such as DIFS and a randomly determined backoff period based on CSMA / CA, and the carrier sense result is idle (CCA). If (Clear Channel Assessment value is below the threshold value), the access right (transmission right) to the wireless medium shall be acquired.

FIG. 2 shows an example of the UL-MU-MIMO sequence according to the first embodiment.

The access point 11 selects wireless terminals 1 to 4 as targets for permitting UL-MU-MIMO transmission, and generates a trigger frame 71 including the authorized terminal information for which the selected wireless terminal is specified. The access point 11 transmits the trigger frame 71, and the wireless terminals 1 to 6 receive the trigger frame 71, respectively. The wireless terminals 1 to 6 analyze the permitted terminal information in the trigger frame 71 to confirm whether or not the own terminal is designated as the target of UL-MU-MIMO transmission. In this example, the wireless terminals 1 to 4 recognize that their own terminal has been designated as the target of UL-MU-MIMO transmission, and the wireless terminals 5 to 6 have been designated as the target of UL-MU-MIMO transmission. Recognize that there is not.

The wireless terminals 1 to 4 transmit data frames 51 to 54 to the access point 11 in the same frequency band after a certain period of time T1 from the completion of reception of the trigger frame 71. That is, data frames are transmitted from wireless terminals 1 to 4 by UL-MU-MIMO. The fixed time T1 may be any value as long as it is a predetermined fixed time. As an example, the SIFS (Short Inter-frame Space) time (= 16 μs), which is the time interval between frames specified in the MAC protocol specification of the IEEE 802.11 wireless LAN, may be used, or may be longer than this (expressed as xIFS). It may be (x represents an arbitrary numerical value). The plurality of data frames 51 to 54 may be the same or different. As a general expression, when it is expressed that a plurality of X-th frames are transmitted or received from each wireless terminal, these X-th frames may be the same or different. Any value can be entered in X depending on the situation.

As a modification, the access point 11 may set the timing at which each wireless terminal should transmit a data frame within the trigger frame, or the time adjustment amount for the fixed time T1. In this case, each wireless terminal grasps the transmission timing of its own terminal based on the setting information of the trigger frame and transmits the data frame. The transmission timing of each wireless terminal does not necessarily have to be the same, and may be individually adjusted so that the reception timing at the access point is the same.

The access point 11 needs to spatially separate the data frame from the signal simultaneously received as a data stream from the wireless terminals 1 to 4. Therefore, the access point 11 utilizes the uplink propagation path response with each of the wireless terminals 1 to 4. In addition to the method of acquiring the uplink propagation path response in advance before transmitting the trigger frame, each of the uplink propagation path responses uses the preamble added to the head side of the data frame transmitted by the wireless terminals 1 to 4 in UL-MU-MIMO. There is also a method of estimating each uplink radio propagation path response from the radio terminal to the access point 11. In this embodiment, an example in which the latter method is used will be described, but there is no problem with the former method.

The preamble consists of a known bit string. The access point 11 can correctly spatially separate (decode) the fields after the preamble (for example, the data field) by estimating the propagation path response of the uplink by using the known bit string. This is a known method, for example, the ZF (Zero-Forcing) method, or the MMSE (Minimum).
It can be performed by any method such as the Mean Square Error method or the maximum likelihood estimation method. As an example, the preamble field is arranged in the physical header (PHY header) arranged at the head side of the MAC frame. The same signal is transmitted from each terminal in each field before the preamble field in the physical header. The preambles of each wireless terminal must be orthogonal to each other. The fact that the preambles are orthogonal means that the access point 11 can individually identify the preamble for each wireless terminal from the signals simultaneously received from each wireless terminal. Thereby, here, the access point 11 can estimate the propagation path from each wireless terminal to the access point 11 by using the preamble for each wireless terminal.

As a method of orthogonalizing the preamble between wireless terminals, any of temporal, frequency, and code methods may be used. In the case of time orthogonality, the preamble field is divided into a plurality of sections, and each terminal transmits the preamble in different sections. In a certain section, only one of the terminals is transmitting the preamble. That is, the temporal positions for transmitting the preamble are different between the terminals. While one terminal sends a preamble, the other terminal sends nothing. In the case of time orthogonality, the preamble contains not only the data of the preamble to be transmitted, but also information about when to transmit. In the case of frequency orthogonality, each terminal transmits preamble data at frequencies that are orthogonal to each other. In the case of frequency orthogonality, the preamble also contains information about which frequency (subcarrier) to transmit. In the case of sign orthogonality, each terminal transmits data in which a plurality of values (symbols corresponding to each of the plurality of values) included in different rows (or different columns) of the orthogonal matrix are arranged. Each row (or each column) of the orthogonal matrix is orthogonal to each other.
In any of the orthogonalization methods, the access point 11 can identify the preamble of each terminal.

In order for each wireless terminal to use a preamble that is orthogonal to each other, it is necessary to give information on the preamble used by each wireless terminal. Specifically, in the case of time orthogonality, the preamble is transmitted at what timing. Information on which frequency to send the preamble in the case of frequency orthogonality, and which coding pattern (which row or column pattern of the orthogonal matrix) to send the preamble in the case of sign orthogonality. Is required.
This information may be set for each wireless terminal that allows UL-MU-MIMO transmission within the trigger frame transmitted by the access point 11. Alternatively, this information may be notified to each wireless terminal in advance by another method. In any case, it is assumed that each wireless terminal can grasp the preamble information used by each wireless terminal in some way when performing UL-MU-MIMO transmission.

The data frames 51 to 54 transmitted from each wireless terminal have a general MAC frame configuration, and are, for example, a Frame Control field, a Duration field, an RA (Receiver Addless) field, a TA (Transmitter Addless) field, and a Frame Body field. , FCS (Frame Check Sequence) field and the like. In this case, the data body transmitted by each wireless terminal to the access point is stored in the Frame Body field.
The MAC address of the access point is stored in the RA field, and the MAC address of the wireless terminal is stored in the TA field. As the MAC address of the access point set in the TA field, the one set in the TA field of the trigger frame (see FIG. 3) may be used.

FIG. 3 shows an example of the format of the trigger frame. For example, it includes a Frame Control field, a Duration field, an RA field, a TA field, a common information field, a terminal information field, and an FCS field.

Information such as Type and Subtype that specifies the type of frame and the like is set in the Frame Control field.

A value of the media reservation time is set in the Duration field. The device that receives the frame in which the value is set in the Duration field counts down until this time set in this field becomes 0, and recognizes that the radio medium is virtually busy until it reaches 0. Such a mechanism for virtually determining that the wireless medium is busy, or a period during which the medium is virtually busy is called a NAV (Network Allocation Vector).

In the RA (Receiver Addless) field, the MAC address of the reception destination of the frame is usually set. Since the trigger frame is transmitted to a plurality of wireless terminals, a broadcast address or a multicast address is set in the RA field. As a modification, if a configuration in which a plurality of RA fields are provided can be provided, the MAC address (unicast address) of the wireless terminal may be set in each RA field.

The TA (Transmitter Addless) field contains the MAC address of the device that is the source of the frame. In the case of a trigger frame, the MAC address or BSSID of the access point is set in the TA field.

In the common information field, information to be notified in common to each wireless terminal that allows UL-MU-MIMO transmission in order to perform UL-MU-MIMO transmission is set. For example, the value of the physical packet length (PDUU length) or MAC frame length (MPDU (medium access control (MAC) protocol data unit) length) for UL-MU-MIMO transmission to the selected wireless terminal may be set. The adjustment amount of the transmission timing of UL-MU-MIMO transmission may be specified. In this case, transmission is performed from each wireless terminal by shifting the adjustment amount with respect to the time after T1 by a certain time from the completion of the trigger frame reception. Further, when the number of terminal information fields described later is variable, information representing the number of terminal information fields may be set in the common information field.

A terminal information field (individual information field) is provided for each wireless terminal that allows UL-MU-MIMO transmission. The number of terminal information fields may be variable depending on the number of wireless terminals that allow UL-MU-MIMO. In the example of FIG. 2, four terminals, a terminal information field 1, a terminal information field 2, a terminal information field 3, and a terminal information field 4, are provided.

The terminal information field includes identification information of a wireless terminal that is permitted to transmit UL-MU-MIMO, and information necessary for the wireless terminal to perform uplink transmission. For example, it includes information about the preamble used by the wireless terminal. As a modification, it is possible to set the identification information of the wireless terminal in the common information field instead of the terminal information field. In this case, the terminal information field corresponding to each wireless terminal may be specified from the position of the identification information of each wireless terminal in the common information field. The identification information of the wireless terminal is not limited to a specific one as long as the wireless terminal can be identified. For example, a MAC address, an Association ID (AID), or both, or any other ID that can identify the terminal can be used.

In the example of FIG. 3, the terminal information field and the common information field are arranged in the MAC header of the MAC frame, but may be arranged in the frame body field. In this case, the type of Frame Control Field of the trigger frame may be Management. Further, as shown in FIG. 4, a terminal information field and a common information field may be set in the physical header (PHY header) added to the head side of the MAC frame. The PHY header is L-STF (Legacy-Short Training).
Field), L-LTF (Legacy-Long Training Field), L-SIG (Legacy Signal Field), common information field, terminal information field are included. L-STF, L-LTF, and L-SIG are fields in which legacy standards such as IEEE802.11a can be recognized, and information such as signal detection, frequency correction, and transmission speed are stored. In the following description, it is assumed that the trigger frame has the format shown in FIG.

Each wireless terminal receives a trigger frame transmitted from the access point 11, and the identification information of its own terminal is included in one of the terminal information fields (or the common information field, or both the terminal information field and the common information field). If so, it is possible to know that the user is designated as a permission target for UL-MU-MIMO transmission. For example, the identification information of the wireless terminals 1 to 4 is set in the terminal information fields 1 to 4, and by detecting the identification information of the own terminal, the wireless terminals 1 to 4 grasp that the own terminal has been designated. ..

Further, when the preamble information used by each wireless terminal is notified by a trigger frame, the preamble information used by each wireless terminal may be set in each terminal information field. Each wireless terminal transmits a data frame using the preamble specified in the terminal information field containing the identification information of the own terminal. As a result, the preambles of the data frames transmitted by each wireless terminal are transmitted in an orthogonal form, and the access point can separate these data frames simultaneously received from these wireless terminals.

As a method of designating wireless terminals to be permitted to transmit UL-MU-MIMO, in addition to the method of setting the identification information of each wireless terminal, the identification information (called a group ID) of the group to which these wireless terminals belong is set. It may be a method.

The access point 11 combines a plurality of wireless terminals having established a wireless link to generate one or more groups. For example, the group 1 is a set of wireless terminals 1, 2, 3, and 4, the group 2 is a set of wireless terminals 1, 3, 4, and the group 3 is a set of wireless terminals 1, 2, 4, 5. The number of groups may be any number, and one wireless terminal may belong to a plurality of groups.

The access point 11 notifies each wireless terminal of the grouping result (list of group ID and wireless terminal) using a dedicated frame, so that each wireless terminal can determine in advance which group its own terminal belongs to. Can be grasped. The access point 11 may add a new group as appropriate, or may change the combination of wireless terminals belonging to an existing group. The access point 11 notifies using a dedicated frame each time a group is added or changed, or both.

In addition, preamble information used by a plurality of wireless terminals belonging to the same group may also be notified to the wireless terminals for each group. This information may be the same frame as the frame that notifies the result of grouping, or may be another frame (trigger frame, etc.). Specify preambles that are orthogonal to each other for wireless terminals that belong to the same group.

Each wireless terminal knows in advance which group the own terminal belongs to and which preamble the own terminal uses. Therefore, the access point 11 can specify a wireless terminal that allows UL-MU-MIMO transmission only by notifying the group ID of the group of the wireless terminal that wants to allow UL-MU-MIMO with a trigger frame. When notifying the group ID in the trigger frame, for example, the group ID may be set in the common information field. The group ID may be the same as the group ID defined in IEEE802.11ac, or may be a different group ID. When the group ID set in the common information field indicates the group to which the own terminal belongs, the wireless terminal that has received the trigger frame means that the local terminal is a wireless terminal to which UL-MU-MIMO transmission is permitted. Recognize.

FCS information is set in the FCS (Frame Check Sequence) field. As an example of FCS information, there is CRC (cyclic redundancy code) information. The FCS information is used on the receiving device side for error detection of the frame body field.

Next, a method in which the access point 11 makes a delivery confirmation response to a data frame received by UL-MU-MIMO from each wireless terminal will be described.

After receiving data frames from a plurality of wireless terminals by UL-MU-MIMO, the access point 11 inspects the CRC using the FCS field of each data frame. Depending on whether or not the data frames can be correctly received from each wireless terminal, the access point 11 creates one delivery confirmation response frame containing the result of error detection of these data frames.

At this time, the access point 11 can include notification information in the delivery confirmation response frame, which specifies a wireless terminal that allows UL-MU-MIMO transmission of the new data frame, if necessary. The new data frame is a data frame other than the data frame transmitted by the current UL-MU-MIMO transmission (for example, the data frames 51 to 54 in FIG. 2). The notification information may include information on the preamble used by the designated wireless terminal.

Hereinafter, the delivery confirmation response frame that does not include the notification information may be referred to as a “normal delivery confirmation response frame”, and the delivery confirmation response frame that includes the notification information may be referred to as a “delivery confirmation response frame with a notification function”.

FIG. 5 shows a format example of a normal delivery confirmation response frame. This frame format includes, for example, a Frame Control field, a Duration field, an RA field, a TA field, a Bitmap field, and an FCS field.

Since the delivery confirmation response frame is transmitted to a plurality of wireless terminals, a broadcast address or a multicast address is set in the RA field as an example. Alternatively, the MAC address (unicast address) of one of the plurality of wireless terminals to be the target of the delivery confirmation response may be set in the RA field. In this case, the wireless terminal specified by the trigger frame 71 stores the information of the other wireless terminal specified by the trigger frame 71, and the address of the other wireless terminal is set in the RA field of the delivery confirmation response frame. If so, this delivery confirmation response frame is interpreted as a frame to be received by the local terminal.

Since the Frame Control field, Duration field, TA field, and FCS field are the same as the trigger frame, the description thereof will be omitted.

The Bitmap field is a field that reflects the CRC result (successful reception) of the data frame received from each wireless terminal. Specifically, each bit of the bitmap represents the CRC result of one data frame. When CRC = OK (reception success), it is represented by "1", and when CRC = NG (reception failure), it is represented by "0". The relationship between "1" and "0" may be reversed. As a result, each wireless terminal that has received the delivery confirmation response frame can grasp the transmission result (success or failure) of the data frame transmitted by the own terminal by referring to the Bitmap field. Which wireless terminal inspection result is mapped to which bit of the bitmap may be specified in advance in the common information field of the trigger frame, or notified in advance in a frame different from the trigger frame. It may be specified by another method other than these. For example, the position of the terminal information field and the position of the bit of the bitmap are associated in advance, and the bit corresponding to the designated terminal information field of the own terminal may be grasped as a bit for the own terminal.

FIG. 6 shows an example of the format of the delivery confirmation response frame with the notification function. The format of FIG. 6 differs from the normal delivery confirmation response frame shown in FIG. 5 in that a common information field and a terminal information 1 field to a terminal information n (n is 1 or more) between the Bitmap field and the FCS field. The point is that the (integer) field is added.

These added fields play basically the same role as those with the same field name included in the trigger frame format shown in FIG. Utilizing these added fields (common information field and terminal information field), the access point 11 specifies a wireless terminal that allows UL-MU-MIMO transmission of a new data frame in the delivery confirmation response frame. ..

Specifically, the access point 11 transmits a new data frame in the common information field, the terminal information field (individual information field), or both of them in the delivery confirmation response frame with the notification function of FIG. Specify the wireless terminal to allow. For example, in each terminal information field, identification information of a wireless terminal for which UL-MU-MIMO transmission is permitted and information required by the terminal for performing UL-MU-MIMO transmission are set. Information that specifies a wireless terminal that is permitted to transmit a new data frame may be stored in the PHY header (see FIG. 4).

The wireless terminal that allows UL-MU-MIMO transmission specified in the delivery confirmation response frame with notification function, for example, transmitted a wireless terminal whose inspection result (CRC result) was successful, or data frames 51 to 54. A wireless terminal (for example, wireless terminals 5 and 6) that has established a wireless link other than the wireless terminal, or both of them. The maximum number of wireless terminals that can be specified here is a value obtained by subtracting the number of terminals whose inspection result fails from the maximum number of wireless terminals that can be multiplexed. Therefore, when a wireless terminal to be permitted to transmit is specified in the terminal information field of the delivery confirmation response frame with the notification function, the maximum number of terminal information fields may exist.

If the terminal can transmit multiple data streams (MIMO transmission) and can transmit different data frames in these data streams, the inspection result of one data frame fails and the inspection of the other data frame is inspected. It may be designated as a wireless terminal that allows transmission of new data frames, such as when the result is successful.

Further, the access point 11 can be configured to specify a wireless terminal that allows UL-MU-MIMO transmission by setting a group ID in the common information field of the delivery confirmation response frame with the notification function. In this case, as an example, a group ID of a group to which a wireless terminal that needs to be retransmitted and a wireless terminal that allows transmission of a new data frame belong is set.
In this case, if the wireless terminal that has transmitted any of the data frames 51 to 54 belongs to the group of the group ID, it can be determined that the data frame is retransmitted on the assumption that the CRC result is unsuccessful. On the other hand, a wireless terminal that does not belong to the group can be judged to have a successful inspection result. In the case of this configuration, the wireless terminal to which the transmission of the new data frame is permitted by the group ID did not transmit the data frames 51 to 54 this time among the wireless terminals having established the wireless link with the access point 11. It is a wireless terminal (a wireless terminal that was not subject to CRC inspection). When the method described here is used, the Bitmap field can be eliminated.

Alternatively, as another method, each wireless terminal that needs to be retransmitted is made to know that it should be retransmitted in the Bitmap field or the like, and the group ID of the group to which only the wireless terminal that allows transmission of a new data frame belongs is set. It is also possible to set it in the common information field.

The delivery confirmation frame with a notification function shown in the example of FIG. 6 may be defined as a “delivery confirmation response frame” as a frame type, or a frame having a different name, for example, “delivery confirmation response + Poll frame” or the like. May be defined as. In the former case, a common information field, a terminal information field, or both are added to the normal frame format shown in FIG. 5 as needed. In the latter case, in the Frame Control field, the format of FIG. 5 and the format of FIG. 6 can be defined separately by Type and Subtype. In this case, each wireless terminal checks the Frame Control field to determine which format of FIG. 5 or FIG. 6 has received the frame. As an example, when a wireless terminal other than the wireless terminal to be inspected receives a delivery confirmation response frame, and the frame type is "delivery confirmation response + Poll frame", the common information field, the terminal information field, or both of them. Check if your terminal is designated as a transmission permission terminal by referring to. When the frame type is "delivery confirmation response frame", it can be understood that the information specifying the local terminal is not included, so that the frame may be ignored.

By transmitting the delivery confirmation response frame with the notification function in the format of FIG. 6, the access point 11 determines the delivery confirmation response to each wireless terminal transmitted immediately before and the designation of the wireless terminal that is permitted to transmit the new data frame. Can be done at the same time. Therefore, the delivery confirmation response frame with the notification function in the format shown in FIG. 6 plays two roles of the delivery confirmation response to each wireless terminal transmitted immediately before and the designation of the wireless terminal that is permitted to transmit the new data frame. It can be said that it is a possible frame.

The access point 11 can determine in any way which format of FIG. 5 and FIG. 6 produces the delivery acknowledgment frame. For example, if the inspection results of all wireless terminals are reception failure, normal format, otherwise, that is, if the inspection results of one or more wireless terminals are successful, the format of the delivery confirmation frame with notification function. May be used. It may be determined by other methods.

The access point 11 transmits the delivery confirmation response frame thus generated in either format after a certain period of time T2 (see FIG. 2) from the reception of the data frames 51 to 54.

Here, the fixed time T2 may be any value as long as it is a predetermined fixed time. As an example, SIFS (Short Inter-frame Space) time (= 16 μs), which is a time interval between frames specified in the MAC protocol specification of the IEEE 802.11 wireless LAN, can be used. Alternatively, a fixed time (xIFS) set separately may be used.

The access point 11 may perform carrier sense before transmitting the delivery confirmation response frame based on CSMA / CA, and transmit the delivery confirmation response frame after acquiring the transmission right.

The wireless terminal that has transmitted the data frames 51 to 54 confirms the inspection result of the own terminal included in the delivery confirmation response frame, and thereby grasps whether the data frame transmitted by the own terminal has been correctly received by the access point.

When the delivery confirmation response frame is in the normal format (FIG. 5), the wireless terminal indicating that the inspection result fails retransmits the data frame at a predetermined time T3 after the reception of the delivery confirmation response frame. (See data frames 61 and 62 in FIG. 2). That is, when the inspection results of the plurality of wireless terminals are unsuccessful, the retransmission data frames are transmitted from the plurality of wireless terminals by UL-MU-MIMO. At this time, the wireless terminal whose inspection result is successful and the wireless terminal other than the wireless terminal that transmitted the data frames 51 to 54 (the wireless terminal other than the wireless terminal subject to the CRC inspection) do not transmit.

Here, the time T3 may be any value as long as it is a predetermined fixed time. As an example, SIFS (Short Inter-frame Space) time (= 16 μs), which is a time interval between frames specified in the MAC protocol specification of the IEEE 802.11 wireless LAN, can be used. Alternatively, a fixed time (xIFS) set separately may be used.

On the other hand, in the case of the delivery confirmation response frame with the notification function, as in the case of the normal delivery confirmation response frame, the wireless terminal whose inspection result is unsuccessful is after a predetermined time T3 from the completion of receiving the delivery confirmation response frame. The data frame is retransmitted at the timing of (see data frames 61 and 62 in FIG. 2). Further, for the wireless terminal whose inspection result was successful and the wireless terminal other than the wireless terminal that transmitted the data frames 51 to 54 (radio terminal not subject to CRC inspection), the own terminal is designated in the delivery confirmation response frame. Check if. For example, it is confirmed whether the identification information of the own terminal is set in the common information field, the terminal information field, or both of them. Whether the delivery confirmation response frame is in the normal format or the format with the notification function may be determined by, for example, Type and Subtype in the Frame Control field. Alternatively, the format used may be determined, for example, from the length of the data contained in the physical header. The judgment may be made by a method other than the method described here.

The wireless terminal specified in the delivery confirmation response frame with the notification function transmits a new data frame at the timing (the same timing as the retransmission data frame) after the above time T3 from the completion of receiving the delivery confirmation response frame (FIG. 2). See data frames 63 and 64). As a result, the wireless terminal specified in the delivery confirmation response frame can also be transmitted at the same time at the transmission timing at which the wireless terminal that failed to transmit retransmits. That is, the wireless terminal that resends and the wireless terminal specified in the delivery confirmation response frame perform UL-MU-MIMO transmission together.

When one wireless terminal simultaneously transmits a plurality of data frames in a plurality of data streams (MIMO transmission), transmission may fail in some data frames and transmission may succeed in another part of the data frames. In this case, in the delivery confirmation response frame with the notification function, the failed data frame is specified by a bitmap or the like, and it is determined whether or not the own terminal is specified in the terminal information field or the like. If the local terminal is specified, the data frame that failed to be transmitted and the new data frame are simultaneously transmitted (MIMO) by a plurality of data streams. That is, the wireless terminal performs frame transmission when the transmission of the data frame fails or when at least one of the cases where the own terminal is specified is established.

In the above-described form, the delivery confirmation response frame represents the inspection result by Bitmap, which represents the CRC result of each wireless terminal in 1 bit, but includes information capable of grasping the inspection result of all the wireless terminals that transmitted the data frame. It is not limited to this as long as it is in the form of. For example, an aggregation frame (super frame) in which ACK (Acknowledgement) frames, which are delivery acknowledgment frames including inspection results of one wireless terminal, are aggregated for all wireless terminals may be transmitted. The aggregation frame is called A-MPDU (A (Aggregated) -MPDU) in the IEEE 802.11 standard.

Further, the frame transmitted by each wireless terminal in UL-MU-MIMO may be an aggregation frame in which a plurality of data frames are aggregated. That is, each wireless terminal may transmit an aggregation frame including a plurality of data frames by UL-MU-MIMO. In this case, the delivery confirmation response frame returned by the access point 11 needs to have a format in which the CRC result of the data frame group in each aggregation frame of each wireless terminal can be grasped. As a method of reflecting the CRC result of the data frame group in each aggregation frame, any method may be used as long as the correspondence can be obtained. As an example, a method similar to the Block Ac frame specified in the MAC protocol specification of the IEEE 802.11 wireless LAN can be used. Further, a frame called Multi-Station Block Ac, which is a diversion of the Block Ac frame described later, or a frame obtained by extending the frame may be used.

Hereinafter, a specific example of the operation of this system will be shown with reference to FIG. As described above, the wireless terminals 1 to 4 whose transmission permission is specified by the trigger frame 71 transmit the data frames 51 to 54 by UL-MU-MIMO after the lapse of time T1 from the completion of the reception of the trigger frame 71.
It is assumed that the access point 11 can correctly receive the data frames 53 and 54 transmitted by the wireless terminal 3 and the wireless terminal 4, but cannot correctly receive the data frames 51 and 52 transmitted by the wireless terminal 1 and the wireless terminal 2.

The access point 11 determines to generate the delivery acknowledgment frame in the format with the notification function shown in FIG. As an example, the access point 11 sets in the Bitmap field information reflecting the CRC result for the data frame transmitted by each wireless terminal in the delivery confirmation response frame. Further, in the delivery confirmation response frame, information or the like for permitting the wireless terminal 5 and the wireless terminal 6 to transmit a new data frame is set.
For example, the identification information of the wireless terminal 5 and the wireless terminal 6 and the individual information to be notified to the wireless terminals 5 and 6 (for example, preamble information) are set in the terminal information 1 field and the terminal information 2 field. Information such as the number of terminal information fields and the physical packet length transmitted by UL-MU-MIMO transmission may be set in the common information field. The access point 11 transmits the delivery confirmation response frame 72 set in this way. The transmitted delivery confirmation response frame 72 is received not only by the wireless terminals 1 to 4 but also by the wireless terminals 5 and 6 that have already established a wireless link with the access point 11.

Among the wireless terminals 1 to 6 that have received the delivery confirmation response frame 72, the wireless terminals 1 to 4 determine whether or not the data frame transmitted by the own terminal has been correctly received based on the Bitmap field. The wireless terminal 1 and the wireless terminal 2 determine that the data frame transmitted by the own terminal has not been correctly received, and retransmit the data frames 61 and 62 at a predetermined retransmission timing. The retransmission timing is, for example, a time T3 elapses after receiving the delivery confirmation response frame.

Further, the wireless terminal 3 and the wireless terminal 4 determine that the data frame transmitted by the own terminal has been correctly received by the access point, and complete the transmission process of the data frame.

On the other hand, when the wireless terminal 5 and the wireless terminal 6 receive the delivery confirmation response frame, the wireless terminal 5 determines whether or not the own terminal has received permission to transmit the new data frame UL-MU-MIMO based on the terminal information field or the like. Here, since each terminal information field contains each identification information, it is determined that transmission permission has been obtained. The wireless terminal 5 and the wireless terminal 6 that have received the transmission permission specify the data frames 63 and 64 in their respective terminal information fields and the like after the elapse of the predetermined time T3 after receiving the delivery confirmation response frame. Send by method. The predetermined time referred to here is, for example, a time when a fixed time T3 has elapsed from the reception of the delivery confirmation response frame, as in the case of the retransmission timing described above.

The preambles of the frames transmitted from the wireless terminals 1, 2, 5, and 6 are arranged so as to be orthogonal to each other, so that the access point can be upgraded with the wireless terminals 1, 2, 5, and 6 as described above. The propagation path information of the link can be grasped, and the frames received from the wireless terminals 1, 2, 5, and 6 can be correctly separated.

The access point 11 receives the retransmission data frames 61 and 62 from the wireless terminals 1 and 2 and the new data frames 63 and 64 from the wireless terminals 5 and 6 by UL-MU-MIMO. It inspects whether each data frame has been received normally, and generates a delivery confirmation response frame 73 including each inspection result and, if necessary, authorized terminal information that specifies a terminal that is authorized to transmit a new data frame. The access point 11 transmits the delivery confirmation response frame 73 when a predetermined time T4 has elapsed from the reception of each data frame. The time T4 may be SIFS, or may be a separately determined time (xIFS). After that, the same process is repeated as necessary.

As described above, the data frames 61 and 62 retransmitted by the wireless terminal 1 and the wireless terminal 2 and the new data frames 63 and 64 transmitted by the wireless terminal 5 and the wireless terminal 6 are transmitted in spatial multiplexing at the same timing, that is, UL-MU-MIMO is transmitted. Therefore, it is possible to keep the number of user multiplex of UL-MU-MIMO transmission above a certain level even at the time of retransmission.

FIG. 7 is a functional block diagram of the wireless communication device of the access point 11. The access point 11 may include a wireless communication device connected to a network (first network) on the wireless terminal side, and may also include a wireless communication device connected to another network (second network). FIG. 7 shows the configuration of a wireless communication device connected to the first network.

The wireless communication device includes a control unit 101, a transmission unit 102, a reception unit 103, antennas 12A, 12B, 12C, 12D, and a buffer 104. The control unit 101 controls communication with the wireless terminal, and the transmission unit 102 and the reception unit 103 form a wireless communication unit as an example. All or part of the processing of the control unit 101 and the processing of the digital area of the transmission unit 102 and the reception unit 103 may be performed by software (program) running on a processor such as a CPU, or by hardware. It may be done by both these software and hardware. The access point may include a processor that performs all or part of processing of the control unit 101, the transmission unit 102, and the reception unit 103.

The buffer 104 is a storage unit for passing frames such as data frames between the upper layer and the control unit 101. The buffer 104 may be a volatile memory such as DRAM or a non-volatile memory such as NAND or MRAM. The upper layer stores the frame received from the second network in the buffer 104 for relaying to the first network, and receives the frame received from the first network from the control unit 101 via the buffer 104. The upper layer may perform communication processing higher than the MAC layer, such as TCP / IP or UDP / IP. Further, the upper layer may be an application layer that processes data. The operation of the upper layer may be performed by processing software (program) by a processor such as a CPU, may be performed by hardware, or may be performed by both software and hardware.

The control unit 101 mainly performs a part of the processing of the MAC layer and the processing of the physical layer (including, for example, MIMO-related processing). The control unit 101 controls communication with each wireless terminal in the first network by transmitting and receiving frames via the transmission unit 102 and the reception unit 103. Further, the control unit 101 may be controlled to periodically transmit the beacon frame. The control unit 101 may include a clock generation unit that generates a clock. Further, the control unit 101 may be configured so that a clock is input from the outside. The control unit 101 may manage the internal time by the clock generated by the clock generation unit, the externally input clock, or both of them. The control unit 101 may output the clock created by the clock generation unit to the outside.

The control unit 101 receives an association request from a wireless terminal and executes an association process to establish a wireless link with the wireless terminal. Before receiving the association request, a process such as authentication may be performed as necessary. The control unit 101 may periodically check the buffer 104, check the buffer 104 by an external trigger, and check whether there is data to be transmitted. The control unit 101 determines to start UL-MU-MIMO transmission from the wireless terminals for which a wireless link has been established by some judgment, selects a plurality of wireless terminals that allow UL-MU-MIMO transmission, and selects these. Generates a trigger frame containing authorized terminal information that specifies the wireless terminal of. Further, the control unit 101 provides information (common information, individual information, or both) for designating a data frame transmission method to each wireless terminal as necessary, such as a common information field of the trigger frame and terminal information. Set to fields or both.

The control unit 101 transmits the generated trigger frame via the transmission unit 102. As an example, the carrier sense is performed during the DIFS and the backoff period, and when the carrier sense result becomes idle and the transmission right can be acquired, the control unit 101 outputs the generated trigger frame to the transmission unit 102. The transmission unit 102 includes a transmission system corresponding to each antenna, and uses a specific transmission system or a plurality of transmission systems to perform desired physical layer processing such as modulation processing and addition of a physical header to the input trigger frame. Do. Further, DA conversion, filter processing for extracting signal components in a desired band, and frequency conversion (up-conversion) are performed on the processed frame of the physical layer. The transmission unit 102 amplifies the frequency-converted signal and radiates it as radio waves into space from one antenna or a plurality of antennas.

The signal received by each antenna of the access point is processed by the receiving unit 103 for each receiving system corresponding to the antenna. For example, after the above-mentioned trigger frame is transmitted, the signals of the data frames returned from the plurality of wireless terminals specified by the trigger frame are simultaneously received by each antenna (UL-MU-MIMO reception). The reception signal of each antenna is input to each reception system in the reception unit 103. Each received signal is amplified in the receiving system, frequency-converted (down-converted), and a desired band component is extracted by a filtering process. Each extracted signal is further converted into a digital signal by AD conversion, undergoes physical layer processing such as demodulation, and then is input to the control unit 101, respectively.

The control unit 101 acquires the uplink propagation path response by estimating the propagation path based on the preamble of the signal input from each reception system. Based on the uplink propagation path response obtained by estimation, the control unit 101 performs the part after the preamble added to the head side of the data frame (the part after the preamble of the header of the physical packet) for each wireless terminal. By separating into, the data frame of each wireless terminal is separated.

Further, the control unit 101 generates a delivery confirmation response frame based on the reception result of the data frame transmitted by UL-MU-MIMO from each wireless terminal. More specifically, the control unit 101 performs a CRC check of each data frame received from each wireless terminal, and generates a delivery confirmation response frame storing information representing each CRC result. The control unit 101 controls to transmit the delivery confirmation response frame after a certain period of time from the completion of receiving the data frame from each wireless terminal.

Here, as the types of the delivery confirmation response frame, as described above, there are a normal delivery confirmation response frame and a delivery confirmation response frame with a notification function. When generating a delivery confirmation response frame with a notification function, the control unit 101 selects a wireless terminal that newly permits UL-MU-MIMO transmission, and inputs the permitted terminal information that specifies these wireless terminals to the above delivery confirmation response. Add to frame.

As an example of the method of selecting a wireless terminal, among the wireless terminals for which a wireless link has been established, the wireless terminal that was not the target of the CRC inspection this time (the data frame was not transmitted by the UL-MU-MIMO this time). It can be selected by any method such as a method of selecting from a wireless terminal), a method of selecting from a wireless terminal whose inspection result was successful, or a method of selecting from both of these.

The number of wireless terminals to be selected is, for example, equal to or less than the maximum number of terminals that can be spatially multiplexed by the access point 11 minus the number of terminals whose inspection result was unsuccessful.

As a method of notifying the information specifying the selected wireless terminal, the identification information of the selected wireless terminal may be set in the common information field, the terminal information field for each wireless terminal, or both of them. Alternatively, it is also possible to arrange the identification information of the group to which the selected wireless terminal belongs in common in the common information field or the like.

The destination address of the delivery confirmation response frame is, for example, a broadcast address or a multicast address. Alternatively, there is also a method in which the unicast address of one of the wireless terminals specified in the trigger frame (the wireless terminal that transmitted the data frame in the UL-MU-MIMO this time) is used as the receiving address.

The transmission unit 102 inputs a delivery confirmation response frame to one or more of the plurality of transmission systems. In the transmission system to which the delivery confirmation response frame is input, the input delivery confirmation response frame is modulated, and physical layer processing such as addition of a physical header is performed on the modulated signal. Further, DA conversion, filter processing for extracting signal components in a desired band, and frequency conversion (up-conversion) are performed on the processed frame of the physical layer. The transmission unit 102 amplifies the frequency-converted signal and radiates it as radio waves into space from one antenna or a plurality of antennas.

The control unit 101 may access and read the information transmitted to each wireless terminal, the information received from each wireless terminal, or a storage device for storing both of them. The storage device may be a buffer (internal memory) provided in the control unit 101 or a buffer (external memory) provided outside the control unit 101. The storage device may be a volatile memory or a non-volatile memory. In addition to the memory, the storage device may be an SSD, a hard disk, or the like.

The above-mentioned separation of processing between the control unit 101 and the transmission unit 102 is an example, and another form is also possible. For example, the control unit 101 may perform the processing in the digital domain, and the transmission unit 102 may perform the processing after the DA conversion. Similarly, regarding the separation of the processes of the control unit 101 and the receiving unit 103, the processing up to the AD conversion is performed by the receiving unit 103, and the processing of the digital region including the subsequent processing of the physical layer is performed by the control unit 101. Good. Isolation other than that described here may be performed.

FIG. 8 is a functional block diagram of a wireless communication device mounted on the wireless terminal 1 according to the present embodiment. Since the wireless communication device mounted on the wireless terminals 2 to 6 has the same configuration as the wireless terminal 1, the description of the wireless terminal 1 will be replaced with the description of the wireless terminals 2 to 6 below.

The wireless communication device includes a control unit 201, a transmission unit 202, a reception unit 203, an antenna 1A, and a buffer 204. The control unit 201 controls communication with the access point 11, and the transmission unit 202 and the reception unit 203 form a wireless communication unit as an example. All or part of the processing of the control unit 201 and the processing of the digital area of the transmitting unit 202 and the receiving unit 203, or the processing of the control unit may be performed by software (program) operating on a processor such as a CPU. , It may be done by hardware, or it may be done by both these software and hardware. Further, a plurality of antennas may be provided in addition to the antenna 1A. The wireless terminal may transmit a plurality of data frames in MIMO using a plurality of antennas. The wireless terminal may include a processor that performs all or part of processing of the control unit 201, the transmission unit 202, and the reception unit 203.

The buffer 204 is a storage unit for passing a frame such as a data frame or data between the upper layer and the control unit 201. The buffer 204 may be a volatile memory such as DRAM or a non-volatile memory such as NAND or MRAM. The upper layer generates frames or data to be transmitted to other wireless terminals, access points 11, or devices on other networks such as servers, stores them in buffer 204, or receives frames received by the first network. It is received via buffer 204. The upper layer may perform communication processing higher than the MAC layer, such as TCP / IP or UDP / IP. Further, the upper layer may be an application layer that processes data. The processing of the upper layer may be performed by software (program) running on a processor such as a CPU, may be performed by hardware, or may be performed by both such software and hardware.

The control unit 201 mainly processes the MAC layer. The control unit 201 controls communication with the access point 11 by transmitting and receiving frames to and from the access point 11 via the transmission unit 202 and the reception unit 203. The control unit 201 receives, for example, a beacon frame periodically transmitted from the access point 11 via the antenna 1A and the reception unit 203. The control unit 201 may include a clock generation unit that generates a clock. Further, the control unit 201 may be configured so that a clock is input from the outside. The control unit 201 may manage the internal time by the clock generated by the clock generation unit or the clock input externally. The control unit 201 may output the clock created by the clock generation unit to the outside.

As an example, the control unit 201 receives a beacon, makes an association request to the access point 11, and executes the association process to establish a wireless link with the access point 11. Prior to the association request, a process such as authentication may be performed as necessary. The control unit 201 may confirm the presence or absence of data to be transmitted by periodically checking the buffer 204 or by checking the buffer 204 by an external trigger such as the buffer 204. After confirming that there is a frame or data to be transmitted to the access point 11, the control unit 201 reads the frame or data and transmits the frame via the transmission unit 202 and the antenna 1A according to the communication method to be used. Alternatively, by receiving at least one of the trigger frame and the delivery confirmation response frame (normal delivery confirmation response frame or delivery confirmation response frame with notification function) from the access point 11, the own terminal is permitted to transmit in UL-MU-MIMO. At the timing, the frame or data is read out and transmitted via the transmission unit 202 and the antenna 1A according to the communication method to be used.

The transmission unit 202 performs processing of a desired physical layer such as modulation processing and addition of a physical header to the frame input from the control unit 201. Further, DA conversion, filter processing for extracting signal components in a desired band, and frequency conversion (up-conversion) are performed on the processed frame of the physical layer. The transmission unit 202 amplifies the frequency-converted signal and radiates it from the antenna into space as a radio wave.

The signal received by the antenna 1A is processed by the receiving unit 203. For example, the signal of the trigger frame is received from the access point 11 and processed by the receiving unit 203. The received signal is amplified by the receiving unit 203, frequency-converted (down-converted), and a desired band component is extracted by file telling processing. Each extracted signal is further converted into a digital signal by AD conversion, undergoes physical layer processing such as demodulation, and then is input to the control unit 201.

When the control unit 201 detects a trigger frame based on the signal input from the reception unit 203, the control unit 201 confirms whether or not the own terminal is designated as the target of UL-MU-MIMO transmission in the trigger frame. For example, it is confirmed whether the identification information of the own terminal is stored in one of the terminal information fields. Alternatively, it is possible to check whether the identification information of the own terminal is stored in the common information field. Alternatively, it is possible to confirm whether or not the own terminal is specified by checking whether the group ID of the group to which the own terminal belongs is specified in the common information field.

When the control unit 201 confirms that the own terminal is specified, the information (common information, individual information) regarding the UL-MU-MIMO transmission method of the own terminal is shared by the trigger frame, if necessary. Check if it is stored in the information field, the terminal information field, or both of these fields. If the information is stored, the information is read from the corresponding field. If the read information includes information on the preamble used when transmitting the data frame of the own terminal, the preamble to be used is specified based on the information. If the preamble to be used in UL-MU-MIMO transmission is specified in advance, the preamble may be used. In this case, the preamble may be obtained by reading the values stored in the buffer, memory, or both.

When the control unit 201 confirms that the own terminal is designated as the target of UL-MU-MIMO transmission in the trigger frame, the control unit 201 reads the data frame or data stored in the buffer 204, identifies the preamble to be used, and specifies the preamble to be used. The data frame is controlled to be transmitted to the access point 11 after a certain period of time from the completion of receiving the trigger frame. The data frame is transmitted via the transmission unit 202 and the antenna 1A. The operation of the transmission unit 202 is as described above.

Further, when the timing of UL-MU-MIMO transmission is specified in the trigger frame, it is possible to control the transmission to the access point 11 at the specified timing.

After transmitting the data frame, the control unit 201 waits for the delivery confirmation response frame transmitted from the access point 11. When the control unit 201 detects a delivery confirmation response frame (a normal delivery confirmation response frame or a delivery confirmation response frame with a notification function) from the access point 11 based on the signal input from the reception unit 203, the control unit 201 causes the own terminal to detect the delivery confirmation response frame. Whether or not the data frame transmitted by the UL-MU-MIMO can be correctly received by the access point 11 is confirmed in the field of the delivery confirmation response frame (normal delivery confirmation response frame or delivery confirmation response frame with notification function). For example, the bit of the own terminal is specified from the Bitmap field of the delivery confirmation response frame, and confirmation is performed based on the specified inspection result. The control unit 201 includes a determination means for determining whether or not the reception of the data frame transmitted by the own terminal is successful at the access point 11.

When the control unit 201 confirms that the data frame transmitted by UL-MU-MIMO has been transmitted correctly, the control unit 201 performs a deletion process of the data frame stored in the buffer 204 as necessary, and transmits the data frame. Complete the process. On the other hand, if it is confirmed that the data frame has not been transmitted correctly, the data frame is retransmitted as necessary.

When performing the retransmission process, the control unit 201 sets "1" for the retry bit of the data frame that could not be transmitted correctly if a retry bit indicating retransmission is defined in the Frame Control field of the data frame. After that, specify the preamble to be used as necessary, and send the data frame to the access point 11 after a certain period of time from the completion of receiving the delivery confirmation response frame (normal delivery confirmation response frame or delivery confirmation response frame with notification function). To control. The data frame is transmitted via the transmission unit 202 and the antenna 1A. If the UL-MU-MIMO transmission timing of the data frame to be retransmitted is specified in the delivery confirmation response frame (normal delivery confirmation response frame or delivery confirmation response frame with notification function), the specified timing. It is also possible to control the access point 11 to transmit the data frame.

Further, when the control unit 201 detects a delivery confirmation response frame from the access point 11 based on the signal input from the reception unit 203, the control unit 201 specifies permission to transmit UL-MU-MIMO of the new data frame (common). Check if the frame has an information field, terminal information field, etc.). That is, the control unit 201 confirms whether or not the detected delivery confirmation frame is a delivery confirmation response frame with a notification function. For example, the judgment may be made based on the Type and Subtype of the Frame Control field, the judgment may be made based on the data length described in the physical header, or the judgment may be made based on both of them. When the control unit 201 identifies that such a field exists in the frame, the control unit 201 confirms whether or not the own terminal is designated as the target of UL-MU-MIMO transmission based on those fields. The control unit 201 includes a determination means for determining whether or not it is designated as a target for UL-MU-MIMO transmission in the delivery confirmation response frame. When the control unit 201 includes, for example, the common information field, one of the terminal information fields, or both of them, the own terminal is determined to be designated. Alternatively, when the group ID of the group to which the own terminal belongs is included in the common information field or the like, it may be determined that the own terminal is specified.

When the control unit 201 confirms that the local terminal is specified, the control unit 201 reads the data frame or data stored in the buffer 204 and uses the preamble as necessary, as in the case of the trigger frame. Is specified, and the data frame is controlled to be transmitted to the access point 11 after a certain period of time from the completion of receiving the delivery confirmation response frame (normal delivery confirmation response frame or delivery confirmation response frame with notification function). The data frame is transmitted via the transmission unit 202 and the antenna 1A. If the UL-MU-MIMO transmission timing is specified in the delivery confirmation response frame (normal delivery confirmation response frame or delivery confirmation response frame with notification function), the access point 11 is sent at the specified timing. It is also possible to control the data frame to be transmitted.

Although the example in which the frame for UL-MU-MIMO transmission is a data frame has been described, it is also possible to transmit various management frames or control frames other than the data frame for UL-MU-MIMO transmission. The various management frames or control frames may be stored in buffer 204. Various management frames or control frames may be generated each time transmission is required.

The control unit 201 may access the storage device for storing the information transmitted to the access point 11, the information received from the access point 11, or both of them, and read the information. The storage device may be a buffer (internal memory) provided in the control unit 201 or a buffer (external memory) provided outside the control unit 201. The storage device may be a volatile memory or a non-volatile memory. In addition to the memory, the storage device may be an SSD, a hard disk, or the like.

The above-mentioned separation of processing between the control unit 201 and the transmission unit 202 is an example, and another form is also possible. For example, the control unit 201 may perform the processing in the digital domain, and the transmission unit 202 may perform the processing after the DA conversion. Similarly, regarding the separation of the processing of the control unit 201 and the reception unit 203, the processing up to the AD conversion is performed by the reception unit 203, and the processing of the digital area including the subsequent processing of the physical layer is performed by the control unit 201. Good. Isolation other than that described here may be performed.

FIG. 9 shows a flowchart of the operation of the access point according to the first embodiment. The control unit of the access point selects a plurality of wireless terminals (or a plurality of wireless communication devices) that are permitted to transmit UL-MU-MIMO (S101), and sets a trigger frame including the permitted terminal information that specifies the selected wireless terminal. Generate (S102). The control unit of the access point transmits the trigger frame via the wireless communication unit after acquiring the access right for transmission (S103). The trigger frame may further include information other than the permitted terminal information, for example, preamble information used by a plurality of wireless terminals in UL-MU-MIMO transmission.

The control unit of the access point transmits a frame such as a data frame transmitted by spatial multiplexing from a plurality of wireless terminals specified by the trigger frame after a predetermined time has elapsed after transmitting the trigger frame. Receive via (S104). That is, the access point receives a plurality of frames transmitted by UL-MU-MIMO from the plurality of wireless terminals. Since the preambles of the frames received from each wireless terminal are orthogonal to each other, these frames received from each wireless terminal at the same time can be separated from each other. If the wireless terminal does not hold the data to be transmitted to the access point, the wireless terminal may not transmit the frame, or may transmit a frame containing no data (for example, QoS Null Frame).

The control unit of the access point generates a delivery confirmation response frame including the inspection result of whether or not the frame received from each wireless terminal has been successfully received and the permitted terminal information for designating at least one wireless terminal. , The generated delivery confirmation response frame is transmitted (S105).
As an example, the inspection result of each wireless terminal may be represented by a bitmap of success or failure of each wireless terminal.

The control unit of the access point is spatially multiplexed from the wireless terminal whose inspection result indicates failure and the wireless terminal newly specified in the delivery confirmation response frame after a predetermined time has elapsed from the transmission of the delivery confirmation response frame. Receives the frame (S106). The preambles of these frames are arranged so that they are orthogonal to each other so that the access point can separate these frames from each other.

FIG. 10 is a flowchart of the operation of the wireless terminal according to the first embodiment. The control unit of the wireless terminal receives the trigger frame including the permitted terminal information designating the plurality of wireless terminals transmitted from the access point via the wireless communication unit (S201). The trigger frame may include information other than the permitted terminal information, for example, preamble information used by each of the plurality of wireless terminals.

The control unit of the wireless terminal receives the trigger frame, and if the own terminal is specified in the permitted terminal information, wirelessly performs a frame such as a data frame after a predetermined time has elapsed from the completion of receiving the trigger frame. It is transmitted to the access point via the communication unit (S202).
The preambles of frames transmitted by a plurality of wireless terminals are orthogonal to each other. As a result, transmission is performed simultaneously and in the same frequency band (spatial multiplexing) from each wireless terminal. That is, UL-MU-MIMO transmission is performed from the plurality of wireless terminals to the access point.

The control unit of the wireless terminal receives the delivery confirmation response frame transmitted from the access point after a lapse of a predetermined time after the transmission of the frame (S203). The delivery confirmation response frame includes an inspection result as to whether or not the access point has succeeded in receiving the frame from each wireless terminal, and permission terminal information for designating at least one wireless terminal. The control unit of the wireless terminal identifies the inspection result of the own terminal from the delivery confirmation response frame, and determines whether or not the transmission of the frame is successful based on the identified inspection result (S204). In addition, it is determined whether or not the own terminal is specified by the permitted terminal information in the delivery confirmation frame (S205). If the inspection result indicates a failure, or if the own terminal is specified in the permitted terminal information, the wireless terminal will use the frame via the wireless communication unit after a predetermined time has elapsed from the completion of receiving the delivery confirmation response frame. Is transmitted (S206). Since the preambles of the frames transmitted by the own terminal and the other wireless terminal are orthogonal to each other, spatial multiplex transmission can be performed from the own terminal and the other wireless terminal. If the inspection result indicates a transmission failure of the own terminal in step S204, it is possible to omit step S205. Further, the order of step S205 and step S204 may be exchanged. In this case, when it is determined in step S205 that the own terminal is specified in the permitted terminal information, it may be considered that the frame transmission is successful without checking the inspection result of the own terminal.

As described above, in the present embodiment, in the delivery confirmation response frame for UL-MU-MIMO transmission, the data of retransmission is included by including the inspection result of each wireless terminal and the information specifying the wireless terminal that allows new transmission. User multiplex transmission (UL-MU-MIMO transmission) of a frame and a new data frame can be performed. As a result, even when there is a wireless terminal that retransmits, it is possible to keep the number of user multiplex above a certain level, and it is possible to improve system throughput by improving efficiency.

In the above-described embodiment, the case of UL-MU-MIMO transmission has been described as the uplink user multiplex transmission method, but the same can be applied to the case of UL-OFDMA transmission. UL-OFDMA allocates one or more subcarriers to terminals as resource units (which may be called subchannels, resource blocks, frequency blocks, etc.) and simultaneously receives from multiple wireless terminals on a resource unit basis. It is a communication method. A resource unit is a frequency component that is the smallest unit of a resource for communication.

FIG. 11 shows resource units (RU # 1, RU # 2, ... RU # K) secured in a continuous frequency domain of one channel (described here as channel M). A plurality of subcarriers orthogonal to each other are arranged in the channel M, and a plurality of resource units including one or a plurality of continuous subcarriers are defined in the channel M. One or more subcarriers (guard subcarriers) may be arranged between resource units, but guard subcarriers are not essential. Each subcarrier in the channel may be numbered to identify the subcarrier. The bandwidth of one channel is, for example, 20 MHz, 40 MHz, 80 MHz, 160 MHz, and the like, but is not limited thereto. A plurality of 20 MHz channels may be combined into one channel. The number of subcarriers or resource units in the channel may vary depending on the bandwidth. The minimum width of the resource unit may be defined, and a plurality of resource units having the minimum width may be concatenated to form one resource unit. Uplink OFDMA communication can be realized by using different resource units simultaneously by a plurality of wireless terminals. It is also possible to set the resource unit as a 20 MHz channel and allocate the resource unit to each terminal in units of 20 MHz channels.

In the case of UL-MU-MIMO, the data stream of each wireless terminal is spatially separated by preamble, but in the case of UL-OFDMA, each terminal may be separated by a resource unit. Since each resource unit is orthogonal in frequency, different resource units do not interfere with each other, and the access point can communicate with a plurality of wireless terminals at the same time. When UL-OFDMA is used as the user multiplex transmission method in the sequence of FIG. 2, the access point specifies information that identifies a different resource unit for each wireless terminal in each terminal information field of the trigger frame 71 instead of the preamble. .. The wireless terminals 1, 2, 3, and 4 may transmit data frames 51 to 54 using the resource unit specified in the corresponding terminal information field of the trigger frame. Such replacement of UL-MU-MIMO with UL-OFDMA can also be applied to the embodiments described later.

In addition, a communication method (referred to as OFDMA & MU-MIMO) in which OFDMA and MU-MIMO (Multiple-Input Multiple-Automat) are combined is also possible. In the case of OFDMA & MU-MIMO, a plurality of terminals use the same resource unit to perform MU-MIMO transmission.

(Second Embodiment)
In the first embodiment, the wireless terminals (radio terminals 1 and 2 in FIG. 2) whose inspection result fails in the delivery confirmation response frame retransmits the data frame after the reception of the delivery confirmation response frame is completed (UL-MU-). MIMO transmission). That is, the failure test result has a role of implicitly giving an instruction or permission for the next UL-MU-MIMO transmission after a certain time from the completion of receiving the delivery confirmation response frame.

In the present embodiment, all wireless terminals that instruct or permit (hereinafter, unified to permit) UL-MU-MIMO transmission performed after the reception of the delivery confirmation response frame is completed are specified in the terminal information field or the common information field. Wireless terminals not specified in the terminal information field or common information field shall not be allowed to transmit UL-MU-MIMO even if the inspection result is unsuccessful. In this way, the wireless terminal that allows UL-MU-MIMO transmission is explicitly specified in the terminal information field or the common information field.

A radio terminal that is permitted to transmit UL-MU-MIMO in the terminal information field or the common information field of the delivery confirmation response frame transmits the frame after a time T3 from the completion of receiving the delivery confirmation response frame. Similar to the first embodiment, the preamble used when transmitting the frame is orthogonal to other permitted wireless terminals. The frame transmitted by the wireless terminal whose inspection result is unsuccessful may be a retransmission frame of the frame whose transmission has failed, or may be a new frame different from this. When the sequence of FIG. 2 is described from the viewpoint of the present embodiment, the wireless terminals 1 and 2 that have failed to transmit the data frames 51 and 52 recognize that the transmission has failed in the bitmap of the delivery confirmation response frame 72. Then, for example, UL-MU-MIMO transmission is performed by inspecting whether there is a field in which the identifier of the own terminal is set in the terminal information fields 1 to N and detecting the field in which the identifier of the own terminal is set. Know what was allowed. Then, the data frames 61 and 62 are transmitted after a time T3 from the completion of receiving the delivery confirmation response frame 72. The data frames 61 and 62 are retransmission frames of the data frames 51 and 52 in the example of FIG. 2, but the data frames 61 and 62 are not limited to these, and may be new data frames. After transmitting a new data frame, the retransmission frames of the data frames 51 and 52 may be transmitted at another transmission opportunity.

Further, the wireless terminal that permits UL-MU-MIMO transmission in the delivery confirmation response frame may be a wireless terminal whose inspection result is successful. An example of the sequence in this case is shown in FIG. At least one of the wireless terminals 3 and 4 that succeeded in transmitting the data frames 53 and 54 may be permitted to transmit UL-MU-MIMO again in the delivery confirmation response frame. In the example of FIG. 12, the wireless terminal 3 that succeeded in transmitting the data frame 53 is permitted to transmit UL-MU-MIMO again in the delivery confirmation response frame 75, and transmits the data frame 65. In addition, wireless terminals 1 and 2 that failed to transmit data frames 51 and 52 and wireless terminals 6 that were not specified in the trigger frame 71 are also permitted. Although the wireless terminal 1 fails to transmit the data frame 51, it transmits a new data frame 66 instead of the retransmission frame of the data frame 51. The wireless terminal 2 fails to transmit the data frame 52, and transmits the retransmission frame 62 of the data frame 52.

Further, the wireless terminal that allows UL-MU-MIMO transmission in the delivery confirmation response frame may be selected from wireless terminals other than the wireless terminal whose inspection result is unsuccessful. An example of the sequence in this case is shown in FIG. In this example, the wireless terminals 3 and 4 that succeeded in transmitting the data frames 53 and 54 and the wireless terminals 5 and 6 not specified by the trigger frame 71 permit the UL-MU-MIMO transmission in the delivery confirmation response frame 76. Has been made. The wireless terminals 3, 4, 5, and 6 transmit data frames 65, 66, 63, and 64 after a time T3 from the completion of receiving the delivery confirmation response frame 76.

Further, the wireless terminal that allows UL-MU-MIMO transmission in the delivery confirmation response frame may be selected from the wireless terminals whose inspection result is unsuccessful. An example of the sequence in this case is shown in FIG. In this example, only the wireless terminals 1 and 2 that failed to transmit the data frames 51 and 52 are permitted to transmit UL-MU-MIMO in the delivery confirmation response frame 77. When there is no wireless terminal that has a request for transmitting new data, the access point may specify only the wireless terminal that needs to be retransmitted in this way. Further, by reducing the number of terminals that transmit UL-MU-MIMO, interference between data streams of a plurality of terminals can be reduced, so that even if there is a wireless terminal that has a request for transmitting new data, retransmission is necessary. It may be effective to preferentially retransmit the data frame by selecting only the wireless terminal. When UL-OFDMA is used as the uplink multiplex transmission method, the smaller the number of terminals, the larger the resource (frequency band) that can be used by one terminal. It also has the advantage of being able to complete the transmission faster.

(Third Embodiment)
In the first and second embodiments, the case where the delivery confirmation response frame is composed of one MAC frame (MPDU) is shown. That is, the success / failure information (bitmap) of each wireless terminal and the permitted terminal information which is the information of the wireless terminal that permits uplink transmission are set in one MAC frame. In the present embodiment, the delivery confirmation response frame is configured as an aggregation frame (A-MPDU), and the delivery confirmation response frame and the trigger frame are stored in the aggregation frame. The success / failure information of each wireless terminal is set in the delivery confirmation response frame, and the permitted terminal information is set in the trigger frame. The configuration of the trigger frame may be the same as in the first and second embodiments (see FIG. 3 or 4).

FIG. 15 shows an example of an operation sequence according to the present embodiment. The transmission of the delivery confirmation response frame 72 and the transmission of the aggregation frame 78 in FIG. 2 have been changed. As an example, the aggregation frame 78 can be configured as an 802.11 standard A-MPDU. As shown in FIG. 16, the aggregation frame 78 is configured by connecting the delivery confirmation response frame 78A and the trigger frame 78B. A delimiter (not shown) is arranged between the delivery confirmation response frame 78A and the trigger frame 78B, whereby the two frames can be distinguished from each other. A physical header is actually added to the head side of the aggregation frame 78. The order of connecting the delivery confirmation response frame and the trigger frame may be reversed.

As an example, the configuration of the delivery confirmation response frame 78A can be the same as that of the normal delivery confirmation response frame of FIG. As the setting method of each field, the same method as the normal delivery confirmation response frame of FIG. 5 can be used. As an example, the trigger frame 78B can use the same configuration as the trigger frame of FIG. As the setting method of each field, the same method as the trigger frame of FIG. 3 can be used. In the sequence of FIG. 15, the radio terminals 1 to 4 that are permitted to transmit in the trigger frame 71 and transmit UL-MU-MIMO confirm the bitmap of the delivery confirmation response frame 78A in the aggregation frame 78, and confirm the bitmap of the delivery confirmation response frame 78A of the own terminal. Check the transmission result (success or failure). The other wireless terminals 5 and 6 ignore the delivery confirmation response frame 78A. Regarding the trigger frame 78B in the aggregation frame 78, all the wireless terminals 1 to 6 that have received the aggregation frame 78 confirm this, and confirm whether the own terminal is permitted to transmit UL-MU-MIMO. In the example of FIG. 15, wireless terminals 1, 2, 5, and 6 are allowed, and these terminals transmit data frames 61, 62, 63, and 64 after a time T3 from the completion of reception of the aggregation frame 78 (UL-MU-MIMO). Send. Here, the aggregation frame in which the delivery confirmation response frame and the trigger frame are concatenated is transmitted from the access point, but in the UL-MU-MIMO transmission from a plurality of wireless terminals to the access point, the aggregation frame in which a plurality of data frames are concatenated is transmitted. You may send each.

Further, the delivery acknowledgment frame 78A can be configured by reusing the Block Acc frame (BA frame) instead of the format shown in FIG. When reusing a BA frame, the frame type may be Control and the frame subtype may be BlockAck, as in the case of a normal BA frame. A frame in which the BA frame is reused in this way may be called a Multi-Station Block Ac (Multi-STA BA). FIG. 17A shows an example of a frame format when the BA frame is reused. FIG. 17B shows an example of the format of the BA Control field in the BA frame, and FIG. 17C shows an example of the format of the BA Information field in the BA frame. When reusing BA frames, it may be indicated in the BA Control field that it is an extended BA frame format for notifying delivery acknowledgments for multiple radio terminals. For example, in the 802.11 standard, when the Multi-TID subfield is 1 and the Compressed Bitmap subfield is 0, the current status is reserved. This may be used to indicate that it is an extended BA frame format for notifying delivery acknowledgments for a plurality of wireless terminals. Alternatively, in FIG. 17B, the area of bits B3-B8 is a reserved subfield, and a part or all of this area is extended in a BA frame format for notifying a delivery acknowledgment regarding a plurality of wireless terminals. It may be defined to indicate that. Alternatively, it is not necessary to explicitly give the notification as described here.

The RA field in the BA frame may be a broadcast address or a multicast address, as in the normal delivery confirmation response frame of FIG. Alternatively, it may be the unicast address of one of the wireless terminals transmitted by UL-MU-MIMO. In the Multi-User subfield of the BA Control field, the number of users (number of terminals) to be reported in the BA Information field may be set. In the BA Information field, for each user (wireless terminal), a subfield for setting an association ID (Association ID: AID) (described as Per TID Info in FIG. 17 (C)) and a block ack start sequence control (block ack). The Starting Sequence Control subfield and the Block Ack Bitmap subfield are arranged.

AID is set in the association ID subfield to identify the user. The Block Ack start sequence control subfield and the Block Ack bitmap subfield may be omitted if the frame transmitted by the wireless terminal is a single data frame (if it is not an aggregation frame). When the frame transmitted by the wireless terminal is an aggregation frame, the block ack start sequence control subfield contains the sequence number of the first MSDU (medium access control (MAC) service data unit) of the delivery acknowledgment indicated by the block ack frame. Store. In the Block Acc bitmap subfield, a bitmap (Block Acc bitmap) consisting of bits for success or failure of reception of each sequence number after the Block Ack start sequence number may be entered.

When the delivery confirmation response frame 78A is a frame in which the BA frame is reused, the terminal receiving the delivery confirmation response frame 78A confirms the Type and Subtype of the frame control field of the delivery confirmation response frame 78A. When it is detected that these are control and BlockAck, then the RA field is checked, and since this value is broadcast or the like, for each data frame in the frame transmitted by the own terminal (here, the aggregation frame). The success / failure information is specified from the Block Ack Bitmap field, and the success / failure of transmission of each data frame is determined. For example, the TID Info subfield that stores the AID of the own terminal is specified from within the BA Information field, and the value (start sequence number) set in the Block Acck Starting Sequence Control subfield that follows the specified TID Info subfield. ) Is specified, and whether or not the transmission of each sequence number after the start sequence number is successful is specified from the Block Acx bitmap. The bit length of the AID may be shorter than the length of the TID Info subfield, and the AID is set to, for example, a part of the TID Info subfield (for example, 11 bits (B0-B10) from the beginning of 2 octets (16 bits)). It may be stored.

When a plurality of wireless terminals transmit a single data frame instead of an aggregation frame and the BA frame is diverted to perform a delivery confirmation response, for example, the following may be performed. One bit (for example, of 2 octets (16 bits), the 12th bit from the beginning (B11 if the beginning is B0)) in the TID Info subfield of each BA information field is a bit (ACK) indicating whether it is ACK or BA. / BA bit), and set a value indicating ACK in the bit. When a value indicating ACK is set, the Block Acack Starting Sequence Control subfield and the Block Acack Bitmap subfield are omitted. As a result, it is possible to notify the ACK of a plurality of terminals in one BA frame. When a plurality of wireless terminals as described above transmit an aggregation frame, a value indicating BA may be set in the ACK / BA bit.
As a result, regardless of whether the plurality of wireless terminals transmit an aggregation frame or a single data frame, the BA frame can be diverted to perform a delivery confirmation response to the plurality of wireless terminals.

In the above description, the aggregation frame 78 is commonly transmitted to the wireless terminals 1 to 6, but different aggregation frames may be transmitted for each wireless terminal by DL-MU-MIMO. For example, suppose that an aggregation frame (a plurality of data frames are concatenated) is received from wireless terminals 1 to 4 and an aggregation frame in which a BA frame and a trigger frame are concatenated is transmitted to each. In this case, as shown in FIG. 18, an aggregation frame including a BA frame and a trigger frame is generated for each wireless terminal, and DL-MU-MIMO is transmitted to the wireless terminals 1 to 4, respectively. The BA frame in each aggregation frame is a frame different for each wireless terminal, and the MAC address of the corresponding wireless terminal is set in the RA field. The trigger frame in each aggregation frame is also a different frame for each wireless terminal, and the MAC address of the corresponding wireless terminal is set in the RA field. As a modification, it is also possible to set a broadcast address or a multicast address in these RA fields. Further, as another modification, the MAC addresses of the corresponding wireless terminals are set in each of these RA fields, and the BA Information field of the BA frame in each aggregation frame and the terminal information field of the trigger frame of all wireless terminals are set. It is also possible to set information.

Alternatively, it is also possible to perform DL-MU-MIMO transmission so that the aggregation frame is unicast-transmitted to some wireless terminals for each wireless terminal and the aggregation frame is broadcast-transmitted to other wireless terminals. .. For example, the access point receives the aggregation frame (connecting a plurality of data frames) from the wireless terminals 1 to 4, and transmits the aggregation frame in which the BA frame and the trigger frame are connected to the wireless terminals 1 and 2 by unicasting. DL-MU-MIMO is transmitted to the wireless terminals 1 to 4 by transmitting the aggregation frame in which the Multi-Station Block Ac (Multi-STA BA) and the trigger frame are connected to the wireless terminals 3 and 4 by broadcasting. May be good. FIG. 19 shows an example of a frame in which the access point transmits DL-MU-MIMO in this case. The bottom frame of FIG. 19 is commonly beam-transmitted to the wireless terminals 3 and 4, and the upper and middle frames of FIG. 19 are beam-transmitted to the wireless terminals 1 and 2, respectively. In order to transmit a beam from the access point to the wireless terminal, a downlink propagation path response is required between each antenna of the access point and the antenna of the wireless terminal, but the downlink propagation path response is sounded in advance. It is assumed that the access point has been acquired by following the procedure in.

Further, as shown in FIG. 20, the access point beam-transmits only the BA frame to some wireless terminals (wireless terminals 1 and 2 in this example), and other wireless terminals (wireless terminal 3 in this example). In 4), an aggregation frame in which a BA frame and a trigger frame are connected may be beam-transmitted. Further, as shown in FIG. 21, a trigger frame in which permission terminal information for designating wireless terminals other than wireless terminals 1 to 4 is set may be additionally beam-transmitted to wireless terminals other than wireless terminals 1 to 4. The destination address of the trigger frame is, for example, a broadcast address or a multicast address. When there is only one wireless terminal for beam transmission, the unicast address of the wireless terminal may be used.

In the example shown in FIG. 18, an aggregation frame in which a delivery confirmation response frame (Multi-STA BA frame, BA frame, etc.) and a trigger frame are connected is transmitted, but the frames to be connected are limited to these two types of frames. Not done. For example, in addition to the delivery confirmation response frame and the trigger frame, the downlink data frame may be further concatenated. FIG. 22 shows an example in which a data frame is further connected to the aggregation frame for each wireless terminal shown in FIG.

In the present embodiment, the case of DL-MU-MIMO transmission is shown as the downlink user multiplex transmission method, but DL-OFDMA may be used as the downlink user multiplex transmission method. Although UL-OFDMA has been described in the first embodiment, DL-OFDMA is basically the same as UL-OFDMA except that the communication direction is the downlink direction. In DL-OFDMA, a plurality of resource units are used to simultaneously transmit from an access point to a plurality of wireless terminals. When the plurality of aggregation frames shown in FIG. 18 are transmitted by DL-OFDMA, different resource units may be assigned to the wireless terminals 1 to 4, and the aggregation frames for the wireless terminals 1 to 4 may be transmitted simultaneously by the respective resource units. Further, in the case of FIG. 19, the aggregation frames in the upper and middle stages of FIG. 19 are transmitted using the resource units assigned to the wireless terminals 1 and 2, respectively, and the aggregation frames in the lower part of FIG. 19 are transmitted to the wireless terminals 3 and 4. Transmission may be performed using a common resource unit different from the resource units of the wireless terminals 1 and 2.

The resource unit used for downlink transmission to each wireless terminal does not necessarily have to notify each wireless terminal in advance, and resources to be decoded by each in the physical headers of multiple frames to be downlinked to these wireless terminals. You may set the unit information. In this case, at least a part of the physical header on the head side (referred to as a SIG field here) is transmitted in the frequency band of the channel width including these resource units (see FIG. 11), and the SIG field is all. Make it possible to receive in common with wireless terminals. By setting information for specifying the resource unit assigned to each wireless terminal in the SIG field and referring to the information, each wireless terminal may grasp the resource unit to be received by the own terminal. For example, in the SIG field, the AID of the wireless terminal and the identification information of the resource unit are set in association with each other. In the case of a frame (aggregation frame) transmitted by broadcasting as shown in the lower part of FIG. 19, an ID that specifies a plurality of wireless terminals or all wireless terminals is defined, and the ID and the identification information of the resource unit are associated with each other. And may be set in the above SIG field.

(Fourth Embodiment)
FIG. 23 is a functional block diagram of the base station (access point) 400 according to the fourth embodiment. This access point includes a communication processing unit 401, a transmitting unit 402, a receiving unit 403, antennas 42A, 42B, 42C, 42D, a network processing unit 404, a wired I / F 405, and a memory 406. .. The access point 400 is connected to the server 407 via a wired I / F 405. The communication processing unit 401 has the same function as the control unit 101 described in the first embodiment. The transmitting unit 402 and the receiving unit 403 have the same functions as the transmitting unit 102 and the receiving unit 102 described in the first embodiment.
The network processing unit 404 has the same function as the higher-level processing unit described in the first embodiment. Here, the communication processing unit 401 may internally hold a buffer for transferring data to and from the network processing unit 404. This buffer may be a volatile memory such as DRAM or a non-volatile memory such as NAND or MRAM.

The network processing unit 404 controls data exchange with the communication processing unit 401, data writing / reading with the memory 406, and communication with the server 407 via the wired I / F 405. The network processing unit 404 may perform communication processing higher than the MAC layer and processing of the application layer such as TCP / IP and UDP / IP. The operation of the network processing unit may be performed by processing software (program) by a processor such as a CPU, may be performed by hardware, or may be performed by both software and hardware.

As an example, the communication processing unit 401 corresponds to a baseband integrated circuit, and the transmitting unit 402 and the receiving unit 403 correspond to an RF integrated circuit that transmits and receives frames. The communication processing unit 401 and the network processing unit 404 may be configured by one integrated circuit (one chip). The digital region processing portion and the analog region processing portion of the transmission unit 402 and the reception unit 403 may be composed of different chips. Further, the communication processing unit 401 may execute communication processing higher than the MAC layer such as TCP / IP and UDP / IP. Further, although the number of antennas is four here, it is sufficient that at least one antenna is provided.

The memory 406 stores the data received from the server 407 and the data received by the receiving unit 402. The memory 406 may be, for example, a volatile memory such as DRAM or a non-volatile memory such as NAND or MRAM. Further, it may be SSD, HDD, SD card, eMMC or the like. The memory 406 may be outside the base station 400.

The wired I / F 405 sends and receives data to and from the server 407. In the present embodiment, the communication with the server 407 is performed by wire, but the communication with the server 407 may be performed wirelessly.

The server 407 is a communication device that receives a data transfer request requesting data transmission and returns a response including the requested data, and is assumed to be, for example, an HTTP server (Web server), an FTP server, or the like. However, it is not limited to this as long as it has a function of returning the requested data. It may be a communication device operated by a user such as a PC or a smartphone. Moreover, you may communicate with the base station 400 wirelessly.

When the STA belonging to the BSS of the base station 400 issues a data transfer request to the server 407, a packet related to the data transfer request is transmitted to the base station 400. The base station 400 receives this packet via the antennas 42A to 42D, and the receiving unit 403 executes the physical layer processing and the like, and the communication processing unit 401 executes the MAC layer processing and the like.

The network processing unit 404 analyzes the packet received from the communication processing unit 401.
Specifically, the destination IP address, destination port number, and the like are confirmed. When the data of the packet is a data transfer request such as an HTTP GET request, the network processing unit 404 determines that the data requested by this data transfer request (for example, the data existing in the URL requested by the HTTP GET request) is Check if it is cached in memory 406. The memory 406 stores a table in which a URL (or its reduced representation, for example, a hash value or an alternative identifier) is associated with data. Here, the fact that the data is cached in the memory 406 is expressed as the existence of the cached data in the memory 406.

When the cache data does not exist in the memory 406, the network processing unit 404 transmits a data transfer request to the server 407 via the wired I / F 405. That is, the network processing unit 404 transmits a data transfer request to the server 407 on behalf of the STA. Specifically, the network processing unit 404 generates an HTTP request, performs protocol processing such as adding a TCP / IP header, and passes the packet to the wired I / F 405.
The wired I / F 405 transmits the received packet to the server 407.

The wired I / F 405 receives a packet from the server 407 that is a response to the data transfer request. The network processing unit 404 grasps that the packet is addressed to the STA from the IP header of the packet received via the wired I / F 405, and passes the packet to the communication processing unit 401. The communication processing unit 401 executes the processing of the MAC layer for this packet, the transmitting unit 402 executes the processing of the physical layer, etc., and transmits the packet addressed to the STA from the antennas 42A to 42D.
Here, the network processing unit 404 associates the data received from the server 407 with the URL (or its reduced representation) and stores it in the memory 406 as cache data.

When the cache data exists in the memory 406, the network processing unit 404 reads the data requested by the data transfer request from the memory 406 and transmits this data to the communication processing unit 401. Specifically, an HTTP header or the like is added to the data read from the memory 406, protocol processing such as addition of a TCP / IP header is performed, and a packet is transmitted to the communication processing unit 401. At this time, as an example, the source IP address of the packet is set to the same IP address as the server, and the source port number is also set to the same port number as the server (the destination port number of the packet transmitted by the communication terminal). Therefore, from the viewpoint of STA, it looks as if it is communicating with the server 407. The communication processing unit 401 executes the processing of the MAC layer for this packet, the transmitting unit 402 executes the processing of the physical layer, etc., and transmits the packet addressed to the STA from the antennas 42A to 42D.

By such an operation, the frequently accessed data responds based on the cache data stored in the memory 406, and the traffic between the server 407 and the base station 400 can be reduced. The operation of the network processing unit 404 is not limited to the operation of the present embodiment. Any general cache proxy that fetches data from server 407 instead of STA, caches the data in memory 406, and responds to data transfer requests for the same data from the cached data in memory 406. For example, there is no problem with another operation.

The transmission of frames, data or packets used in the first to third embodiments described above may be executed using the cached data stored in the memory 406.

The base station (access point) of the present embodiment can be applied as the base station of the first to third embodiments. In the present embodiment, the base station having a cache function has been described, but a terminal (STA) having a cache function can also be realized with the same block configuration as in FIG. 23. In this case, the wired I / F 405 may be omitted.

(Fifth Embodiment)
FIG. 24 shows an example of the overall configuration of a terminal (including the case of an access point).
This configuration example is an example, and the present embodiment is not limited thereto. The terminal includes one or more antennas 1 to n (n is an integer of 1 or more), a wireless LAN module 148, and a host system 149. The wireless LAN module 148 corresponds to the wireless communication device according to any one of the first to third embodiments. The wireless LAN module 148 includes a host interface, which is connected to the host system 149. In addition to being connected to the host system 149 via a connection cable, it may be directly connected to the host system 149. Further, the wireless LAN module 148 can be mounted on the board by solder or the like and connected to the host system 149 via the wiring of the board. The host system 149 communicates with an external device by using the wireless LAN module 148 and the antennas 1 to n according to an arbitrary communication protocol. The communication protocol may include TCP / IP and a higher layer protocol. Alternatively, TCP / IP may be mounted on the wireless LAN module 148, and the host system 149 may execute only the protocol of the upper layer. In this case, the configuration of the host system 149 can be simplified. This terminal is, for example, a mobile terminal, TV, digital camera, wearable device, tablet, smartphone, game device, network storage device, monitor, digital audio player, Web camera, video camera, project, navigation system, external adapter, internal It may be an adapter, a set-top box, a gateway, a printer server, a mobile access point, a router, an enterprise / service provider access point, a portable device, a handheld device, or the like.

FIG. 25 shows a hardware configuration example of the wireless LAN module. This configuration is applicable when the wireless communication device is mounted on either a non-access point terminal or an access point. That is, it can be applied as an example of a specific configuration of the wireless communication device shown in FIG. In this configuration example, the number of antennas is only one, but two or more antennas may be provided. In this case, a plurality of sets of transmission system (216, 222-225), reception system (217, 232-235), PLL242, crystal oscillator 243, and switch 245 are arranged corresponding to each antenna, and each set is a base. It may be connected to the band circuit 212.

The wireless LAN module (wireless communication device) is a baseband IC (Integrated).
It includes a Circuit) 211, an RF (Radio Frequency) IC 221 and a balun 225, a switch 245, and an antenna 247.

The baseband IC 211 includes a baseband circuit (control circuit) 212, a memory 213, a host interface 214, a CPU 215, a DAC (Digital to Analog Converter) 216, and an ADC (Analog to Digital Converter) 217.

The baseband IC211 and RF IC221 may be formed on the same substrate. Further, the baseband IC211 and the RF IC221 may be composed of one chip. DAC216 and / or ADC217 may be located in the RF IC 221 or in another IC. Further, the memory 213 and / or the CPU 215 may be arranged in an IC different from the baseband IC.

The memory 213 stores data to be transferred to and from the host system. Further, the memory 213 stores information notified to the terminal or the access point, information notified from the terminal or the access point, or both of them. Further, the memory 213 may store a program necessary for executing the CPU 215 and may be used as a work area when the CPU 215 executes the program. The memory 213 may be a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM.

The host interface 214 is an interface for connecting to the host system. The interface may be anything such as UART, SPI, SDIO, USB, PCI Express and the like.

The CPU 215 is a processor that controls the baseband circuit 212 by executing a program. The baseband circuit 212 mainly processes the MAC layer and the physical layer. The baseband circuit 212, CPU 215, or both correspond to a communication control device that controls communication, or a control unit that controls communication.

At least one of the baseband circuit 212 and the CPU 215 includes a clock generation unit that generates a clock, and the internal time may be managed by the clock generated by the clock generation unit.

The baseband circuit 212 performs addition, coding, encryption, modulation processing (may include MIMO modulation) of a physical header as a physical layer process on the frame to be transmitted, and for example, two types of digital baseband signals (MIMO modulation may be included). Hereinafter, a digital I signal and a digital Q signal) are generated.

The DAC 216 DA-converts the signal input from the baseband circuit 212. More specifically, the DAC 216 converts the digital I signal into an analog I signal and the digital Q signal into an analog Q signal. It should be noted that there may be a case where the signal of one system is transmitted as it is without quadrature modulation. When a plurality of antennas are provided and transmission signals of one system or a plurality of systems are distributed and transmitted by the number of antennas, a number of DACs or the like corresponding to the number of antennas may be provided.

The RF IC 221 is, for example, an RF analog IC, a high frequency IC, or both of them. The RF IC 221 includes a filter 222, a mixer 223, a preamplifier (PA) 224, a PLL (Phase Locked Loop) 242, a low noise amplifier (LNA) 234, a balun 235, a mixer 233, and a filter 232. Some of these elements may be located on baseband IC211 or another IC. The filters 222 and 232 may be a band pass filter or a low pass filter.

The filter 222 extracts a signal in a desired band from each of the analog I signal and the analog Q signal input from the DAC 216. The PLL 242 uses the oscillation signal input from the crystal oscillator 243, and divides or multiplies the oscillation signal, or both, to generate a signal having a constant frequency synchronized with the phase of the input signal. The PLL 242 includes a VCO (Voltage Controlled Oscillator), and obtains a signal having a constant frequency by performing feedback control using the VCO based on an oscillation signal input from the crystal oscillator 243. The generated constant frequency signal is input to the mixer 223 and the mixer 233. The PLL 242 corresponds to an example of a transmitter that generates a signal having a constant frequency.

The mixer 223 up-converts the analog I signal and the analog Q signal that have passed through the filter 222 to a radio frequency by using a signal having a constant frequency supplied from the PLL 242. The preamplifier (PA) 224 amplifies the radio frequency analog I and Q signals generated by the mixer 223 to the desired output power. The balun 225 is a converter for converting a balanced signal (differential signal) into an unbalanced signal (single-ended signal). The RF IC 221 handles balanced signals, but since the unbalanced signals are handled from the output of the RF IC 221 to the antenna 247, the balun 225 performs these signal conversions.

The switch 245 is connected to the transmitting side balun 225 at the time of transmission, and is connected to the receiving side balun 234 or RF IC 221 at the time of receiving. The control of the switch 245 may be performed by the baseband IC211 or the RF IC221, or another circuit for controlling the switch 245 may exist and the switch 245 may be controlled from the circuit.

The radio frequency analog I signal and analog Q signal amplified by the preamplifier 224 are balanced-unbalanced converted by the balun 225, and then radiated as radio waves from the antenna 247 into space.

The antenna 247 may be a chip antenna, an antenna formed by wiring on a printed circuit board, or an antenna formed by using a linear conductor element.

The LNA 234 in the RF IC 221 amplifies the signal received from the antenna 247 via the switch 245 to a level that can be demodulated while keeping noise low. The balun 235 performs an unbalanced-balanced conversion of the signal amplified by the low noise amplifier (LNA) 234. The mixer 233 down-converts the received signal converted into the balanced signal by the balun 235 to the baseband using the signal of a constant frequency input from the PLL 242. More specifically, the mixer 233 has means for generating carriers that are 90 ° out of phase with each other based on the constant frequency signal input from the PLL 242, and the received signals converted by the balun 235 are 90 ° to each other. It is orthogonally demodulated by the out-of-phase carrier wave to generate an I (In-phase) signal having the same phase as the received signal and a Q (Quad-phase) signal having a phase delayed by 90 ° from the I (In-phase) signal. The filter 232 extracts a signal of a desired frequency component from these I signal and Q signal. The I signal and Q signal extracted by the filter 232 are output from the RF IC 221 after the gain is adjusted.

The ADC 217 in the baseband IC 211 AD-converts the input signal from the RF IC 221. More specifically, the ADC 217 converts the analog I signal into a digital I signal and the analog Q signal into a digital Q signal. In some cases, only one system of signals may be received without orthogonal demodulation.

When a plurality of antennas are provided, the number of ADCs may be provided according to the number of antennas. Based on the digital I signal and the digital Q signal, the baseband circuit 212 performs physical layer processing (may include MIMO demodulation) such as demodulation processing, error correction code processing, and physical header processing to obtain a frame. The baseband circuit 212 processes the MAC layer on the frame. If the baseband circuit 212 implements TCP / IP, the baseband circuit 212 can also be configured to perform TCP / IP processing.

Since the details of the processing of each part described above are obvious from the explanations of FIGS. 7 and 8, duplicate description will be omitted.

(Sixth Embodiment)
26 (A) and 26 (B) are perspective views of the wireless terminal according to the sixth embodiment, respectively. The wireless terminal of FIG. 26 (A) is a notebook PC 301, and the wireless terminal of FIG. 26 (B) is a mobile wireless terminal 321. The notebook PC 301 and the mobile wireless terminal 321 are equipped with wireless communication devices 305 and 315, respectively. As the wireless communication devices 305 and 315, the wireless communication device (FIG. 8 or the like) mounted on the wireless terminal described above, the wireless communication device (FIG. 7 or the like) mounted on the access point 11, or these. Both can be used. The wireless terminal equipped with the wireless communication device is not limited to a notebook PC or a mobile wireless terminal. For example, TVs, digital cameras, wearable devices, tablets, smartphones, game devices, network storage devices, monitors, digital audio players, web cameras, camcorders, projects, navigation systems, external adapters, internal adapters, set-top boxes, gateways, etc. It can also be installed in printer servers, mobile access points, routers, enterprise / service provider access points, portable devices, handheld devices, and the like.

Further, the wireless communication device mounted on the wireless terminal, the access point 11, or both of them can also be mounted on the memory card. FIG. 27 shows an example in which the wireless communication device is mounted on a memory card. The memory card 331 includes a wireless communication device 355 and a memory card main body 332. The memory card 331 utilizes the wireless communication device 335 for wireless communication with an external device (wireless terminal, access point 11, or both). Note that in FIG. 27, the description of other elements (for example, memory, etc.) in the memory card 331 is omitted.

(7th Embodiment)
In the seventh embodiment, in addition to the configuration of the wireless communication device (the wireless communication device of the access point, the wireless communication device of the wireless terminal, or both) according to any one of the first to fifth embodiments, the bus , A processor unit, and an external interface unit. The processor unit and the external interface unit are connected to the external memory (buffer) via the bus. Firmware runs in the processor section. By including the firmware in the wireless communication device in this way, it is possible to easily change the function of the wireless communication device by rewriting the firmware. The processor unit on which the firmware operates may be a control unit or a processor that performs processing of the control unit according to the present embodiment, or may be another processor that performs processing related to function expansion or modification of the processing. Good. The processor unit on which the firmware operates may be provided by the access point, the wireless terminal, or both of them according to the present embodiment. Alternatively, the processor unit may be provided with an integrated circuit in a wireless communication device mounted on an access point or an integrated circuit in a wireless communication device mounted on a wireless terminal.

(8th Embodiment)
In the eighth embodiment, in addition to the configuration of the wireless communication device (access point wireless communication device, wireless terminal wireless communication device, or both) according to any one of the first to fifth embodiments, a clock. It has a generator. The clock generator generates a clock and outputs the clock from the output terminal to the outside of the wireless communication device. In this way, the clock generated inside the wireless communication device is output to the outside, and the host side is operated by the clock output to the outside, so that the host side and the wireless communication device side can be operated in synchronization with each other. It will be possible.

(9th Embodiment)
In the ninth embodiment, in addition to the configuration of the wireless communication device (the wireless communication device of the access point or the wireless communication device of the wireless terminal) according to any one of the first to fifth embodiments, the power supply unit and the power supply control unit , And a wireless power supply unit. The power supply control unit is connected to the power supply unit and the wireless power supply unit, and controls to select the power supply to be supplied to the wireless communication device. By providing the wireless communication device with the power supply in this way, it is possible to perform a power consumption reduction operation in which the power supply is controlled.

(10th Embodiment)
The tenth embodiment includes a SIM card in addition to the configuration of the wireless communication device according to the ninth embodiment. The SIM card is connected to a transmitting unit (102 or 202) or a receiving unit (103 or 203) or a control unit (101 or 201) in a wireless communication device, or a plurality of these. In this way, by providing the SIM card in the wireless communication device, it is possible to easily perform the authentication process.

(11th Embodiment)
The eleventh embodiment includes a moving image compression / decompression unit in addition to the configuration of the wireless communication device according to the sixth embodiment. The moving image compression / decompression section is connected to the bus. As described above, by providing the moving image compression / decompression unit in the wireless communication device, it is possible to easily transmit the compressed moving image and decompress the received compressed moving image.

(12th Embodiment)
In the twelfth embodiment, in addition to the configuration of the wireless communication device (access point wireless communication device, wireless terminal wireless communication device, or both) according to any one of the first to fifth embodiments, the LED. Including part. The LED unit is connected to a transmitting unit (102 or 202), a receiving unit (103 or 203), a control unit (101 or 201), or a plurality of these. By providing the LED unit in the wireless communication device in this way, it is possible to easily notify the user of the operating state of the wireless communication device.

(13th Embodiment)
In the thirteenth embodiment, in addition to the configuration of the wireless communication device (the wireless communication device of the access point, the wireless communication device of the wireless terminal, or both) according to any one of the first to fifth embodiments, the vibrator Includes part. The vibrator unit is connected to a transmission unit (102 or 202), a reception unit (103 or 203), a control unit (101 or 201), or a plurality of these. By providing the vibrator unit in the wireless communication device in this way, it is possible to easily notify the user of the operating state of the wireless communication device.

(14th Embodiment)
In the fourteenth embodiment, in addition to the configuration of the wireless communication device (access point wireless communication device, wireless terminal wireless communication device, or both) according to any one of the first to fifth embodiments, a display. including. The display may be connected to the control unit (101 or 201) of the wireless communication device via a bus (not shown). By providing the display in this way and displaying the operating state of the wireless communication device on the display, it is possible to easily notify the user of the operating state of the wireless communication device.

(15th Embodiment)
In this embodiment, [1] a frame type in a wireless communication system, [2] a method of disconnecting a connection between wireless communication devices, [3] an access method of a wireless LAN system, and [4] a frame interval of a wireless LAN will be described.
[1] Frame types in communication systems Generally, as described above, frames handled on a wireless access protocol in a wireless communication system are roughly classified into three frames: a data frame, a management frame, and a control frame. It can be divided into types. These types are usually indicated by a header portion commonly provided between frames. As a display method of the frame type, one field may be capable of distinguishing three types, or a combination of two fields may be used to distinguish between the three types. In the IEEE802.11 standard, the frame type is identified by two fields, Type and Subtype, in the Frame Control field in the frame header part of the MAC frame. The data frame, the management frame, and the control frame are roughly classified in the Type field, and the subtypes in the roughly classified frames, for example, the Beacon frame in the management frame, are identified in the Subtype field.

The management frame is a frame used for managing a physical communication link with another wireless communication device. For example, there are frames used for setting communication with other wireless communication devices, frames for releasing (that is, disconnecting) communication links, and frames for power saving operation in wireless communication devices. ..

A data frame is a frame that transmits data generated inside a wireless communication device to another wireless communication device after establishing a physical communication link with the other wireless communication device. The data is generated in the upper layer of the present embodiment, and is generated by, for example, a user operation.

The control frame is a frame used for control when transmitting (exchanged) a data frame with another wireless communication device. When the wireless communication device receives a data frame or a management frame, the response frame transmitted to confirm the delivery belongs to the control frame. The response frame is, for example, an ACK frame or a BlockACK frame. The RTS frame and CTS frame are also control frames.

These three types of frames are processed as necessary in the physical layer and transmitted as physical packets via the antenna. In addition, the IEEE802.11 standard (the above-mentioned IEEE Std)
In (including extended standards such as 802.11ac-2013), there is an association process as one of the procedures for establishing a connection, but the Association Request frame and the Association Response frame used in it are the management frames, and the Association Request frame. Since the frame and the Association Response frame are unicast management frames, the receiving wireless communication terminal is requested to transmit the ACK frame which is the response frame, and this ACK frame is the control frame as described above.

[2] Method of disconnecting the connection between wireless communication devices There are an explicit method and an implicit method for disconnecting (releasing) the connection. As an explicit method, one of the wireless communication devices having established a connection transmits a frame for disconnection. In the IEEE802.11 standard, the Deatumentation frame corresponds to this and is classified as a management frame. Normally, the wireless communication device on the side that transmits the frame that disconnects the connection disconnects the connection when the frame is transmitted, and the wireless communication device that receives the frame that disconnects the connection receives the frame. judge. After that, if it is a non-base station wireless communication terminal, it returns to the initial state in the communication phase, for example, the state of searching for a BSS to be connected. When the wireless communication base station disconnects from a certain wireless communication terminal, for example, if the wireless communication base station has a connection management table that manages the wireless communication terminals that subscribe to its own BSS, the connection management Delete the information related to the wireless communication terminal from the table. For example, when the wireless communication base station assigns an AID to each wireless communication terminal that subscribes to its own BSS in the association process, the retained information associated with the AID of the wireless communication terminal that disconnected the connection is used. May be deleted and the AID may be released so that it can be assigned to another newly subscribed wireless communication terminal.

On the other hand, as an implicit method, frame transmission (transmission of data frame and management frame, or transmission of response frame to the frame transmitted by the own device) is detected from the wireless communication device of the connection partner with which the connection is established for a certain period of time. If not, the connection status is determined to be disconnected. There is such a method because, in the situation where the disconnection of the connection is determined as described above, the communication distance from the wireless communication device to which the connection is made is so large that the wireless signal cannot be received or decoded. This is because it is possible that the wireless link cannot be secured. That is, the reception of the frame that disconnects the connection cannot be expected.

A timer is used as a specific example of determining the disconnection by an implicit method. For example, when transmitting a data frame requesting a delivery confirmation response frame, a first timer (for example, a retransmission timer for a data frame) that limits the retransmission period of the frame is activated until the first timer expires (that is,). If the delivery confirmation response frame to the frame is not received (until the desired retransmission period elapses), retransmission is performed. The first timer is stopped when the delivery confirmation response frame to the frame is received.

On the other hand, when the first timer expires without receiving the delivery confirmation response frame, for example, it is confirmed whether the wireless communication device of the connection partner still exists (in the communication range) (in other words, whether the wireless link can be secured). At the same time, a second timer (for example, a retransmission timer for the management frame) that limits the retransmission period of the frame is activated. Like the first timer, the second timer retransmits if the delivery confirmation response frame to the frame is not received until the second timer expires, and when the second timer expires, it is determined that the connection has been disconnected. .. When it is determined that the connection has been disconnected, a frame for disconnecting the connection may be transmitted.

Alternatively, when a frame is received from the wireless communication device of the connection partner, the third timer is activated, and each time a frame is newly received from the wireless communication device of the connection partner, the third timer is stopped and the frame is started again from the initial value. When the third timer expires, a management frame is sent to check whether the wireless communication device of the connection partner still exists (in the communication range) (in other words, whether the wireless link is secured) as described above. At the same time, a second timer (for example, a retransmission timer for the management frame) that limits the retransmission period of the frame is activated. In this case as well, if the delivery confirmation response frame to the frame is not received until the second timer expires, retransmission is performed, and when the second timer expires, it is determined that the connection is disconnected. In this case as well, the frame for disconnecting the connection may be transmitted when it is determined that the connection has been disconnected.
The latter management frame for confirming whether the wireless communication device of the connection partner still exists may be different from the management frame in the former case. Further, as the timer for limiting the retransmission of the management frame in the latter case, the same timer as in the former case is used here as the second timer, but a different timer may be used.

[3] Access method of wireless LAN system For example, there is a wireless LAN system that assumes communication or competition with a plurality of wireless communication devices. In the IEEE802.11 wireless LAN, CSMA / CA (Carrier Sense Multiple Access with Carrier Availability) is the basis of the access method. In the method of grasping the transmission of a certain wireless communication device and transmitting after a fixed time from the end of the transmission, the transmission is performed simultaneously by a plurality of wireless communication devices that have grasped the transmission of the wireless communication device, and as a result, the transmission is performed. , Radio signals collide and frame transmission fails. By grasping the transmission of a certain wireless communication device and waiting for a random time from the end of the transmission, the transmission by a plurality of wireless communication devices grasping the transmission of the wireless communication device is stochastically dispersed. Therefore, if there is only one wireless communication device in which the earliest time is subtracted from the random time, the frame transmission of the wireless communication device is successful, and frame collision can be prevented. Since the acquisition of transmission rights is fair among a plurality of wireless communication devices based on a random value, the method adopting Carrier Availability is said to be a method suitable for sharing a wireless medium among a plurality of wireless communication devices. be able to.

[4] Wireless LAN Frame Interval The frame interval of the IEEE802.11 wireless LAN will be described. The frame intervals used in the IEEE802.11 wireless LAN are distributed codedination function interframe space (DIFS), arbitration interframe space (AIFS), point coordination entence spectence , Reduced interframe space (URIFS) and the like.

The definition of the frame interval is defined as a continuous period in which the carrier sense idle should be confirmed and opened before transmission in the IEEE802.11 wireless LAN, and the exact period from the previous frame is not discussed. Therefore, the definition is followed in the description of the IEEE802.11 wireless LAN system here. In the IEEE802.11 wireless LAN, the time to wait for random access based on CSMA / CA is the sum of the fixed time and the random time, and it can be said that this definition is used to clarify the fixed time.

DIFS and AIFS are frame intervals used when attempting to start frame exchange during a contention period that competes with other wireless communication devices based on CSMA / CA. DIFS is used when there is no distinction of priority by traffic type, and AIFS is used when priority is provided by traffic type (Traffic Identity).

Since the operations related to DIFS and AIFS are similar, they will be described mainly using AIFS below. In the IEEE802.11 wireless LAN, access control including the start of frame exchange is performed at the MAC layer. Further, when QoS (Quality of Service) is supported when the data is passed from the upper layer, the traffic type is notified together with the data, and the data is classified into the priority at the time of access based on the traffic type. The class at the time of this access is called an access category (AC). Therefore, the AIFS value is provided for each access category.

PIFS is a frame interval for allowing access with priority over other competing wireless communication devices, and has a shorter period than either the value of DIFS or AIFS. SIFS is a frame interval that can be used when transmitting a control frame of a response system or when continuing frame exchange in a burst after acquiring an access right once. EIFS is a frame interval that is activated when frame reception fails (it is determined that the received frame is an error).

RIFS is a frame interval that can be used when a plurality of frames are continuously transmitted to the same wireless communication device in a burst after the access right is once acquired, and while RIFS is used, the transmission partner's wireless communication device can be used. Does not request a response frame for.

Here, FIG. 28 shows an example of frame exchange during a competing period based on random access in the 802.11 wireless LAN.

It is assumed that when a data frame (W_DATA1) transmission request is generated in a certain wireless communication device, the medium is recognized as busy media as a result of carrier sense. In this case, the AIFS for a fixed time is vacated from the time when the carrier sense becomes idle, and then the data frame W_DATA1 is transmitted to the communication partner when a random time (random backoff) is vacated. If, as a result of the carrier sense, it is recognized that the medium is not busy, that is, the medium is idle, a fixed time AIFS is provided from the time when the carrier sense is started, and the data frame W_DATA1 is communicated with the communication partner. Send to.

The random time is a pseudo-random integer derived from a uniform distribution between the content windows (CW) given as an integer from 0, multiplied by the slot time. Here, the CW multiplied by the slot time is called the CW time width.
The initial value of CW is given in CWmin, and each time it is retransmitted, the value of CW is increased until it reaches CWmax. Both CWmin and CWmax have values for each access category, similar to AIFS. In the wireless communication device of the transmission destination of W_DATA1, if the data frame is successfully received and the data frame is a frame requesting the transmission of the response frame, the occupation of the physical packet containing the data frame ends on the wireless medium. A response frame (W_ACK1) is transmitted after SIFS time from the time point. When the wireless communication device that has transmitted W_DATA1 receives W_ACK1, it transmits the next frame (for example, W_DATA2) after SIFS time from the end of occupancy of the physical packet containing W_ACK1 on the wireless medium if it is within the transmission burst time limit. can do.

AIFS, DIFS, PIFS and AIFS are functions of SIFS and slot time, but SIFS and slot time are defined for each physical layer. In addition, parameters such as AIFS, CWmin, and CWmax for which values are set for each access category can be set for each communication group (Basic Service Set (BSS) in the 802.11 wireless LAN), but default values are set. ..

For example, in the standardization of 802.11ac, SIFS is 16 μs and slot time is 9 μs, so that PIFS is 25 μs, DIFS is 34 μs, and the default value of the frame interval of access category BACKGROUND (AC_BK) in AIFS is 79 μs. The default frame spacing of BEST EFFORT (AC_BE) is 43 μs, the default frame spacing of VIDEO (AC_VI) and VOICE (AC_VO) is 34 μs, and the default values of CWmin and CWmax are 31 and 1023 for AC_BK and AC_BE, respectively. , AC_VI is 15 and 31, and AC_VO is 7 and 15. Note that EIFS is basically the sum of SIFS and DIFS and the time length of the response frame when transmitting at the slowest essential physical rate. In a wireless communication device capable of efficiently taking EIFS, the occupancy time length of the physical packet carrying the response frame to the physical packet that activated EIFS can be estimated, and the sum of SIFS, DIFS, and the estimated time can be used. it can.

The frame described in each embodiment may refer to an IEEE802.11 standard or a compliant standard such as Null Data Packet, which is called a packet.

The terms used in this embodiment should be broadly interpreted. For example, the term "processor" may include general purpose processors, central processing units (CPUs), microprocessors, digital signal processors (DSPs), controllers, microcontrollers, state machines, and the like. In some circumstances, "processor" may refer to application-specific integrated circuits, field programmable gate arrays (FPGAs), programmable logic circuits (PLDs), and the like. A "processor" may refer to a combination of processing devices such as multiple microprocessors, a combination of DSPs and microprocessors, and one or more microprocessors that work with a DSP core.

As another example, the term "memory" may include any electronic component capable of storing electronic information. "Memory" includes random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable PROM (EEPROM), and non-volatile. It may refer to random access memory (NVRAM), flash memory, magnetic or optical data storage, which can be read by a processor. If the processor reads and writes information to the memory, or both, then the memory can be said to communicate electrically with the processor. The memory may be integrated into the processor, again which can be said to be in electrical communication with the processor. Further, the circuit may be a plurality of circuits arranged on a single chip, or may be one or more circuits distributed on a plurality of chips or a plurality of devices.

Further, in the present specification, "at least one of a, b and c" is referred to as a, b, c, ab, and so on.
Includes not only combinations of ac, bc, abc, but also multiple combinations of the same elements such as aa, abb, aabbcc. It is an expression. Further, it is an expression that covers a configuration including elements other than a, b, and c, such as a combination of abc-d.

The present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate.

The description of the scope of claims at the time of filing the patent application of the original application is added.
[Item 1]
A receiver that receives a plurality of first frames transmitted multiple times, and
The reception unit includes a transmission unit for transmitting a second frame including an inspection result of whether or not each of the plurality of first frames has been successfully received and first information specifying at least one wireless communication device. The unit is a wireless communication device that receives a plurality of third frames that are multiplex-transmitted in response to the second frame.
[Item 2]
The wireless communication device according to item 1, wherein the first information specifies a first wireless communication device that has transmitted the first frame in which the inspection result is successful.
[Item 3]
The wireless communication device according to item 1, wherein the first information specifies a second wireless communication device different from the plurality of wireless communication devices that have transmitted the plurality of first frames.
[Item 4]
The wireless communication device according to item 1, wherein the first information specifies a third wireless communication device that has transmitted the first frame in which the inspection result fails.
[Item 5]
The wireless communication device according to any one of items 1 to 4, wherein the second frame is a frame in which a fourth frame including the inspection result and a fifth frame including the first information are aggregated.
[Item 6]
The wireless communication device according to any one of items 1 to 5, wherein the reception address of the second frame is a broadcast address or a multicast address.
[Item 7]
The wireless communication device according to any one of items 1 to 6, wherein the receiving unit receives the plurality of third frames multiplex transmitted only from the plurality of wireless communication devices specified in the first information.
[Item 8]
The receiving unit is the plurality of third frames transmitted by multiplex transmission from the wireless communication device that transmitted the first frame in which the inspection result fails and the at least one wireless communication device specified in the first information. The wireless communication device according to any one of items 1 to 6 for receiving.
[Item 9]
The wireless communication device according to item 1, further comprising at least one antenna.
[Item 10]
A receiver that receives a plurality of first frames transmitted multiple times, and
It is provided with a transmission unit that multiplexes a plurality of second frames including an inspection result as to whether or not each of the plurality of first frames has been successfully received.
Each of at least two of the plurality of second frames includes a third frame including the inspection result of one of the plurality of wireless communication devices that transmitted the plurality of first frames, and the one wireless communication device. It is a frame that aggregates the fourth frame including the first information that specifies the above, and the receiving unit is a plurality of multiple transmissions according to the first information included in the fourth frame of the at least two second frames. A wireless communication device that receives the 5th frame of.
[Item 11]
Yet another one of the plurality of second frames is a third of the plurality of wireless communication devices that transmitted the plurality of first frames, other than the wireless communication device that notified the inspection result in the third frame. The sixth frame containing the inspection result of the two wireless communication devices and the seventh frame containing the second information designating at least one of the second wireless communication devices are aggregated, and the receiving address is broadcast. The wireless communication device according to item 10, which is an address or a multicast address.
[Item 12]
The transmission unit multiplexes the eighth frame including the third information specifying the wireless communication device other than the plurality of wireless communication devices that transmitted the plurality of first frames at the same time as the plurality of second frames. 10. The wireless communication device according to 10.
[Item 13]
At least one of the plurality of second frames includes a ninth frame including the inspection result of one of the plurality of wireless communication devices that transmitted the plurality of first frames, and the one wireless communication device. Item 10. The wireless communication device according to item 10, which is a frame in which the 10th frame including the fourth information for designating the above and the 11th frame including the data addressed to the one wireless communication device are aggregated.
[Item 14]
The wireless communication device according to item 10, further comprising at least one antenna.
[Item 15]
The transmitter that transmits the first frame and
A third frame including the inspection result of whether or not the first frame and the second frame multiplexed with the first frame have been successfully received, and the first information designating at least one wireless communication device are included. Equipped with a receiving unit to receive
The transmitting unit transmits a fourth frame when its own device is specified in the first information, and the fourth frame is transmitted by the first other wireless communication device specified in the first information. A wireless communication device that is multiplexed and transmitted with at least one of the fifth frame and the sixth frame transmitted by the second other wireless communication device that transmitted the second frame in which the inspection result fails.
[Item 16]
The wireless communication device according to item 15, wherein the transmission unit transmits the fourth frame when the inspection result of the first frame fails, even if the own device is not specified in the first information.
[Item 17]
The wireless communication device according to item 15, wherein the fourth frame is a retransmission frame of the first frame when the inspection result of the first frame fails.
[Item 18]
The wireless communication device according to item 15, wherein the fourth frame is not a retransmission frame of the first frame even if the inspection result of the first frame fails.
[Item 19]
The first frame and the second frame are transmitted by either spatial multiplexing or frequency multiplexing, and are transmitted.
The wireless communication device according to item 15, wherein the fourth frame and at least one of the fifth frame and the sixth frame are transmitted by either spatial multiplexing or frequency multiplexing.
[Item 20]
The wireless communication device according to item 15, further comprising at least one antenna.

1: Access points 12A, 12B, 12C, 12D: Antennas 1, 2, 3, 4, 5, 6: Wireless terminals 1A, 2A, 3A, 4A, 5A, 6A: Antennas 21, 22, 23, 24: Beam 71 : Trigger frames 72, 73: Delivery confirmation response frames 51, 52, 53, 54, 63, 64: Data frames 61, 62: Retransmitted data frames T1, T2, T3, T4: Period 101, 201: Control units 102, 202 : Transmitter 103, 203: Receiver 104, 204: Buffer 211: Baseband IC
213: Memory 214: Host interface 215: CPU
216: DAC
217: ADC
221: RF IC
222: 232: Filter 223, 233: Mixer 224, 234: Amplifier 225, 235: Balun 242: PLL
243: Crystal oscillator 247: Antenna 245: Switch 148: Wireless LAN module 149: Host system 301: Notebook PC
305, 315, 355: Wireless communication device 321: Mobile wireless terminal 331: Memory card 332: Memory card main body 42A to 42D: Server 400: Access point 401: Communication processing unit 402: Transmission unit 403: Reception unit 404: Network processing Part 405: Wired I / F
406: Memory

Claims (3)

A receiver that receives a plurality of first frames transmitted multiple times, and
It is provided with a transmission unit that multiplexes a plurality of second frames including an inspection result as to whether or not each of the plurality of first frames has been successfully received.
Each of at least two of the plurality of second frames includes a third frame including the inspection result of one of the plurality of wireless communication devices that transmitted the plurality of first frames, and the one wireless communication device. It is a frame that aggregates the fourth frame including the first information that specifies the above, and the receiving unit is a plurality of multiple transmissions according to the first information included in the fourth frame of the at least two second frames. Received the 5th frame of
Yet another one of the plurality of second frames is a third of the plurality of wireless communication devices that transmitted the plurality of first frames, other than the wireless communication device that notified the inspection result in the third frame. The sixth frame containing the inspection result of the two wireless communication devices and the seventh frame containing the second information designating at least one of the second wireless communication devices are aggregated, and the receiving address is broadcast. A wireless communication device that is an address or a multicast address. The wireless communication apparatus according to claim 1 comprising at least one antenna. Receives multiple first frames to be multiplexed
A plurality of second frames including the inspection result of whether or not each of the plurality of first frames was successfully received are multiplexed and transmitted.
Each of at least two of the plurality of second frames includes a third frame including the inspection result of one of the plurality of wireless communication devices that transmitted the plurality of first frames, and the one wireless communication device. It is a frame that aggregates the 4th frame including the 1st information that specifies
A plurality of fifth frames, which are multiplex-transmitted according to the first information included in the fourth frame of at least two second frames, are received and received.
Yet another one of the plurality of second frames is a third of the plurality of wireless communication devices that transmitted the plurality of first frames, other than the wireless communication device that notified the inspection result in the third frame. The sixth frame containing the inspection result of the two wireless communication devices and the seventh frame containing the second information designating at least one of the second wireless communication devices are aggregated, and the receiving address is broadcast. Address or multicast address
Wireless communication method.

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