JP6702545B2 - Wireless communication device and wireless communication method - Google Patents

Description

Embodiments of the present invention relate to a wireless device and a wireless communication method.

Consider frequency multiplex communication in which transmission to a plurality of terminals or reception from a plurality of terminals are simultaneously performed by using different frequency components as wireless communication terminals (hereinafter, terminals) as communication resources. Here, the frequency component is defined as a resource unit including one or more subcarriers, and the resource unit is used as a minimum unit of communication resources to simultaneously perform transmission to multiple terminals or reception from multiple terminals. Consider an Orthogonal Frequency Division Multiple Access (OFDMA) scheme. Simultaneous transmission from the base station to a plurality of terminals corresponds to downlink OFDMA (DL-OFDMA) transmission, and simultaneous transmission from a plurality of terminals to the base station corresponds to uplink OFDMA (UL-OFDMA) transmission.

When performing uplink OFDMA (UL-OFDMA) communication, it is possible to transmit a trigger frame from the base station in order to align the uplink transmission timing of each terminal. There is a method of designating a terminal that performs UL-OFDMA communication and a resource unit to be used by the terminal by notifying information on an allocated terminal for each resource unit using a trigger frame. This method has a problem in that the use efficiency of communication resources is reduced, such as when the terminal is in a sleep mode or when the terminal does not request uplink transmission. Another method is to specify only the resource unit to be used in the trigger frame without specifying the terminal. In this case, the terminal receiving the trigger frame selects the resource unit based on a method similar to the random backoff method. At this time, if the number of terminals that have received the trigger frame is large, there is a high possibility that the same resource unit will be selected. When multiple terminals transmit a frame using the same resource unit, the base station cannot receive the frame normally.

IEEE 802.11-15/0604r1 IEEE Std 802.11ac(TM)-2013 IEEE Std 802.11(TM)-2012

Embodiments of the present invention aim to efficiently use communication resources to perform uplink frequency multiplexing transmission.

A wireless device according to one aspect of the present invention includes a transmitter that transmits a first frame that includes information designating a plurality of frequency components and that instructs a plurality of wireless communication terminals to perform frequency multiplex transmission, and the plurality of frequencies. A receiver for receiving a second frame with at least one frequency component of the components, wherein the first frame includes a terminal identifier of each of the plurality of wireless communication terminals among the plurality of frequency components. It has either one of a first form of designating in association with at least one and a second form of designating a group identifier of a group to which the plurality of wireless communication terminals belong.

FIG. 3 is a functional block diagram of a wireless communication device according to an embodiment of the present invention. The figure for demonstrating allocation of a resource unit. The figure for demonstrating various structures of a resource unit. The figure which shows the wireless-communications group containing a base station and several terminals. The figure which shows the basic format example of a MAC frame. The figure which shows the example of a format of an information element. The figure which shows the example of the operation sequence which concerns on embodiment of this invention. The figure which shows the example of a format of the physical packet containing a trigger frame. The figure which shows the format example of a trigger frame. The figure which shows the structural example of the RU/AID field in a trigger frame. The figure which shows the other format example of a trigger frame. The figure which shows the other example of a format of a trigger frame. The figure which shows the other example of a format of a trigger frame. The figure which shows the other example of a format of a trigger frame. The figure which shows the other example of a format of a trigger frame. The figure which shows the other example of a format of a trigger frame. The figure which shows the other example of a format of a trigger frame. The figure which shows the flowchart of an example of operation|movement of the base station which concerns on embodiment of this invention. The figure explaining the channel which transmits a trigger frame. The figure which shows the flowchart of an example of operation|movement of the terminal which concerns on embodiment of this invention. The functional block diagram of the base station or terminal which concerns on 2nd Embodiment. .. The figure which shows the whole structural example of the terminal or base station which concerns on 3rd Embodiment. The hardware structural example of the wireless LAN module mounted in the terminal or base station which concerns on 3rd Embodiment is shown. 1 is a perspective view of a wireless communication terminal according to an embodiment of the present invention. The figure which shows the memory card which concerns on embodiment of this invention. The figure which shows an example of frame exchange in a contention period.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. IEEE Std 802.11(TM)-2012 and IEEE Std 802.11ac(TM)-2013, which are known as wireless LAN standards, are all incorporated by reference in this specification. And

(First embodiment)
FIG. 1 shows a functional block diagram of the wireless communication apparatus according to the first embodiment. The wireless communication device can be implemented in a wireless communication base station (hereinafter, base station or access point) or a wireless communication terminal (hereinafter, terminal) that communicates with the base station. A base station is a form of a terminal because it basically has a communication function similar to that of a terminal except that it mainly has a relay function. In the following description, a terminal may refer to a base station unless it is necessary to distinguish the two.

In the present embodiment, it is assumed that a plurality of terminals perform uplink OFDMA (UL-OFDMA: Orthogonal Frequency Division Multiple Access) transmission. In UL-OFDMA, one or more subcarriers are assigned to terminals as resource units (may be called subchannels, resource blocks, frequency blocks, etc.), and reception from a plurality of terminals is performed simultaneously on a resource unit basis. The resource unit is a frequency component that is the minimum unit of resources for communication. FIG. 3 shows resource units (RU#1, RU#2,... RU#K) secured in a continuous frequency domain of one channel (herein, described 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 consecutive subcarriers are defined in the channel M. One or more subcarriers (guard subcarriers) may be arranged between resource units, but the guard subcarriers are not essential. A number for identifying a subcarrier may be assigned to each subcarrier in the channel. The bandwidth of one channel is, for example, 20 MHz, 40 MHz, 80 MHz, 160 MHz, etc., 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 be different depending on the bandwidth. Uplink OFDMA communication is realized by a plurality of terminals simultaneously using different resource units.

The bandwidth (or the number of subcarriers) of the resource unit may be common to each resource unit, or the bandwidth (or the number of subcarriers) may be different for each resource unit. FIG. 3 schematically shows an arrangement pattern example of resource units in one channel. The horizontal direction along the paper corresponds to the frequency domain direction. FIG. 3A shows an example in which a plurality of resource units (RU#1, RU#2,... RU#K) having the same bandwidth are arranged. FIG. 3B shows an example in which a plurality of resource units (RU#11-1, RU#11-2,..., RU#11-L) having a larger bandwidth than that of FIG. 3A are arranged. . FIG. 3C shows an example in which resource units of three types of bandwidth are arranged. The resource units (RU#12-1, RU#12-2) have the largest bandwidth, and the resource unit RU#12-(L-1) has the same bandwidth and resource unit (RU) as in FIG. 3B. #K-1, RU#K) has the same bandwidth as that of FIG.

A specific example is shown. When using the entire 20 MHz channel width, 26 resource units (tones) can be set for 256 subcarriers (tones) arranged in the 20 MHz channel width. That is, 9 resource units are set in the 20 MHz channel width, and the bandwidth of the resource unit is smaller than the 2.5 MHz width. In the 40 MHz channel width, 18 resource units are set. 37 pieces are set in the 80 MHz channel width (see doc.: IEEE 802.11-15/0330r5). When this is developed, for example, in a 160 MHz channel width or an 80+80 MHz channel width, 74 resource units are set. Of course, the width of the resource unit is not limited to a specific value, and resource units of various sizes can be arranged.

The number of resource units used by each terminal is not limited to a specific value, and one or a plurality of resource units may be used. When the terminal uses a plurality of resource units, a plurality of resource units that are consecutive in frequency may be used, or a plurality of resource units that are distant may be used.

It is assumed that the subcarriers in one resource unit are continuous in the frequency domain, but the resource unit may be defined by a plurality of subcarriers arranged discontinuously. The number of channels used in the uplink OFDMA communication is not limited to one, and the same as the case of the channel M in another channel (see the channel N in FIG. 2) located at a position separated from the channel M in the frequency domain. The resource unit may be reserved by using the resource unit in both the channel M and the channel N. The method of arranging the resource units in the channel M and the channel N may be the same or different. The bandwidth of the channel N is, for example, 20 MHz, 40 MHz, 80 MHz, 160 MHz, etc. as described above, but is not limited thereto. It is also possible to use more than two channels. The channel M and the channel N may be collectively considered as one channel.

Note that the terminal that implements OFDMA has at least a channel with a basic channel width (20 MHz channel width if a terminal compatible with the IEEE802.11a/b/g/n/ac standard is a legacy terminal) in a legacy terminal that is a backward compatibility target. Then, a physical packet including a frame can be received and decoded (including demodulation and decoding of error correction code). Carrier sense is performed in units of the basic channel width. The carrier sense is a physical carrier sense (Physical Carrier Sense) regarding busy/idle of CCA (Clear Channel Assessment), and a virtual carrier sense (Virtual Carrier) based on the medium reservation time described in the received frame. Sense) may be included. A mechanism for determining that a medium is virtually busy like the latter, or a period during which a medium is virtually busy is called NAV (Network Allocation Vector). The carrier sense information based on CCA or NAV performed on a channel-by-channel basis may be commonly applied to all resource units in the channel. For example, all resource units belonging to a channel whose carrier sense information indicates idle are idle.

Note that OFDMA can be channel-based OFDMA in addition to the resource unit-based OFDMA described above. The OFDMA in this case may be particularly referred to as MU-MC (Multi-User Multi-Channel). In MU-MC, a base station allocates a plurality of channels (one channel width is, for example, 20 MHz) to a plurality of terminals and simultaneously uses the plurality of channels to perform simultaneous transmission to or reception from a plurality of terminals. To do. In OFDMA described below, a resource unit-based OFDMA is assumed, but an embodiment of channel-based OFDMA can also be realized by performing necessary reading such as replacing the resource unit in the following description with a channel.

In addition, in uplink multiplex transmission from a plurality of terminals to a base station, in addition to OFDMA described above, a communication method (referred to as OFDMA & MU-MIMO) that combines OFDMA and MU-MIMO (Multiple-Input Multiple-Output) is also possible. is there. Uplink MU-MIMO transmission is a method in which a plurality of terminals transmit streams to a base station by spatial multiplexing (simultaneously in the same frequency band), and the base station simultaneously receives these streams by a plurality of antennas. In the case of OFDMA & MU-MIMO, a plurality of terminals use the same resource unit to perform MU-MIMO transmission. In the following description, when referring to OFDMA, OFDMA & MU-MIMO may be used.

In the following description, a terminal capable of implementing UL-OFDMA may be referred to as a UL-OFDMA compatible terminal (or simply an OFDMA compatible terminal) or the like. A terminal that does not have the capability may be called a legacy terminal. When the ability to carry out UL-OFDMA communication can be switched to valid (Enable) or invalid (Disable), the terminal in which the relevant ability is valid may be considered as an OFDMA-compatible terminal.

As shown in FIG. 1, the wireless communication device mounted on a terminal (a terminal of a non-base station and a base station) includes a high-order processing unit 90, a MAC processing unit 10, a PHY (Physical: Physical) processing unit 50, and a MAC/ A PHY management unit 60, an analog processing unit 70 (analog processing units 1 to N) and an antenna 80 (antennas 1 to N) are included. N is an integer of 1 or more. In the figure, the N analog processing units and the N antennas are connected in pairs, but the configuration is not necessarily limited to this. For example, the number of analog processing units may be one, and two or more antennas may be commonly connected to this analog processing unit.

The MAC processing unit 10, the MAC/PHY management unit 60, and the PHY processing unit 50 correspond to one form of a control unit or a baseband integrated circuit that performs a process related to communication with another terminal (including a base station). The analog processing unit 70 corresponds to, for example, a form of a wireless communication unit that transmits and receives a signal via the antenna 80 or an RF (Radio Frequency) integrated circuit. The integrated circuit for wireless communication according to the present embodiment includes at least the former of the baseband integrated circuit (control unit) and the RF integrated circuit. The function of the communication processing device or the baseband integrated circuit may be performed by software (program) that operates on a processor such as a CPU, may be performed by hardware, or may be performed by both software and hardware. You may. The software may be stored in a memory such as a ROM or a RAM, a storage medium such as a hard disk, an SSD, and read and executed by a processor. The memory may be a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM.

The upper processing unit 90 performs processing for the upper layer on the MAC (Medium Access Control) layer. The upper processing unit 90 can exchange signals with the MAC processing unit 10. Typical examples of the upper layer include TCP/IP, UDP/IP, and an application layer thereabove, but the present embodiment is not limited to this. The upper processing unit 90 may include a buffer for exchanging data between the MAC layer and the upper layer. It may be configured to connect to a wired infrastructure via the upper processing unit 90. The buffer may be a memory, an SSD, a hard disk, or the like. When the buffer is a memory, the memory may be a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM.

The MAC processing unit 10 performs processing for the MAC layer. As described above, the MAC processing unit 10 can exchange signals with the upper processing unit 90. Further, the MAC processing unit 10 can exchange signals with the PHY processing unit 50. The MAC processing unit 10 includes a MAC common processing unit 20, a transmission processing unit 30, and a reception processing unit 40.

The MAC common processing unit 20 performs processing common to transmission and reception in the MAC layer. The MAC common processing unit 20 is connected to the upper processing unit 90, the transmission processing unit 30, the reception processing unit 40, and the MAC/PHY management unit 60, and exchanges signals with each other.

The transmission processing unit 30 and the reception processing unit 40 are connected to each other. The transmission processing unit 30 and the reception processing unit 40 are connected to the MAC common processing unit 20 and the PHY processing unit 50, respectively. The transmission processing unit 30 performs transmission processing in the MAC layer. The reception processing unit 40 performs reception processing in the MAC layer.

The PHY processing unit 50 performs processing for the physical layer (PHY layer). As described above, the PHY processing unit 50 can exchange signals with the MAC processing unit 10. The PHY processing unit 50 is connected to the antenna 80 via the analog processing unit 70.

The MAC/PHY management unit 60 is connected to each of the upper processing unit 90, the MAC processing unit 10 (more specifically, the MAC common processing unit 20), and the PHY processing unit 50. The MAC/PHY management unit 60 manages MAC operation and PHY operation in the wireless communication device.

The analog processing unit 70 includes an analog/digital and digital/analog (AD/DA) converter and an RF (Radio Frequency) circuit, and converts the digital signal from the PHY processing unit 50 into an analog signal having a desired frequency and an antenna. A high frequency analog signal transmitted from the antenna 80 and received from the antenna 80 is converted into a digital signal. Although the AD/DA conversion is performed by the analog processing section 70 here, the PHY processing section 50 may be configured to have an AD/DA conversion function.

The wireless communication device according to the present embodiment can suppress the mounting area of the antenna 80 by including (integrating) the antenna 80 in one chip as a component. Further, in the wireless communication device according to the present embodiment, as shown in FIG. 1, the transmission processing unit 30 and the reception processing unit 40 share N antennas 80. Since the transmission processing unit 30 and the reception processing unit 40 share the N antennas 80, the wireless communication device in FIG. 1 can be downsized. The wireless communication device according to this embodiment may of course have a configuration different from that illustrated in FIG.

When receiving a signal from the wireless medium, the analog processing unit 70 converts the analog signal received by the antenna 80 into a signal in the base band (Baseband) that can be processed by the PHY processing unit 50, and further converts the signal into a digital signal. The PHY processing unit 50 receives a digital reception signal from the analog processing unit 70 and detects the reception level thereof. The detected reception level is compared with the carrier sense level (threshold value), and if the reception level is equal to or higher than the carrier sense level, the PHY processing unit 50 is a signal indicating that the medium (CCA: Clear Channel Assessment) is busy. Is output to the MAC processing unit 10 (more accurately, the reception processing unit 40). If the reception level is less than the carrier sense level, the PHY processing unit 50 outputs a signal indicating that the medium (CCA) is idle to the MAC processing unit 10 (more accurately, the reception processing unit 40). ..

The PHY processing unit 50 performs decoding (including demodulation and decoding of error correction code) on the received signal, processing to remove the physical header (PHY header) including the preamble, and the like, and extracts the payload. In the IEEE 802.11 standard, this payload is called a PSDU (Physical Layer Convergence Procedure (PLCP) service data unit) on the PHY side. The PHY processing unit 50 passes the extracted payload to the reception processing unit 40, and the reception processing unit 40 handles this as a MAC frame. In the IEEE802.11 standard, this MAC frame is called MPDU (medium access control (MAC) protocol data unit). In addition, the PHY processing unit 50 notifies the reception processing unit 40 of the start of the reception signal, and notifies the reception processing unit 40 of the reception signal reception end. Further, when the received signal can be normally decoded as a physical packet (PHY packet) (when no error is detected), the PHY processing unit 50 notifies the reception end of the received signal and the medium is idle. To the reception processing unit 40. When the PHY processing unit 50 detects an error in the received signal, the PHY processing unit 50 notifies the reception processing unit 40 that an error has been detected by using an appropriate error code according to the error type. Further, the PHY processing unit 50 notifies the reception processing unit 40 of a signal indicating that the medium is idle when it is determined that the medium has become idle.

The MAC common processing unit 20 mediates the transfer of the transmission data from the upper processing unit 90 to the transmission processing unit 30 and the transfer of the reception data from the reception processing unit 40 to the higher processing unit 90. In the IEEE802.11 standard, the data in this MAC data frame is called MSDU (medium access control (MAC) service data unit). Further, the MAC common processing unit 20 once receives an instruction from the MAC/PHY management unit 60, converts the instruction into a suitable one and outputs it to the transmission processing unit 30 and the reception processing unit 40.

The MAC/PHY management unit 60 corresponds to, for example, SME (Station Management Entity) in the IEEE 802.11 standard. In this case, the interface between the MAC/PHY management unit 60 and the MAC common processing unit 20 corresponds to the MLME SAP (MAC subLayer Management Service Access Point) in the IEEE 802.11 standard, and the MAC/PHY management unit 60 and the PHY. The interface with the processing unit 50 corresponds to a PLME SAP (Physical Layer Management Service Access Point) in an IEEE 802.11 wireless LAN (Local Area Network).

In addition, in FIG. 1, the MAC/PHY management unit 60 is illustrated as if the functional unit for MAC management and the functional unit for PHY management are integrated, but even if they are implemented separately. Good.

The MAC/PHY management unit 60 holds a management information base (Management Information Base: MIB). The MIB holds various information such as the capability of the terminal itself and whether or not various functions are valid or invalid. For example, whether or not the terminal itself is UL-OFDMA compatible, and if it is UL-OFDMA compatible, ON/OFF information of the function of performing UL-OFDMA may be held. The memory for holding and managing the MIB may be included in the MAC/PHY management unit 60, or may be separately provided without being included in the MAC/PHY management unit 60. When a memory for holding and managing the MIB is provided separately from the MAC/PHY management unit 60, the MAC/PHY management unit 60 can refer to the different memory and rewrite the rewritable parameters in the memory. It can be performed. The memory may be a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM. Further, instead of the memory, a storage device such as SSD or hard disk may be used. The base station can also acquire these pieces of information of other terminals as non-base stations by the notification from the terminal. In that case, the MAC/PHY management unit 60 can refer to and rewrite information about other terminals. Alternatively, the memory for storing information regarding these other terminals may be held and managed separately from the MIB. In that case, the MAC/PHY management unit 60 or the MAC common processing unit 20 allows the other memory to be referenced and rewritten. Also, the MAC/PHY management unit 60 of the base station determines a terminal that simultaneously allocates resource units for UL-OFDMA based on various information regarding the terminal as a non-base station or a request from the terminal when implementing UL-OFDMA. A selection function of selecting (that is, selecting a terminal to be the target of UL-OFDMA this time) may be provided. The MAC/PHY management unit 60 or the MAC processing unit 10 may manage the transmission rate applied to the MAC frame and physical header to be transmitted. Further, the MAC/PHY management unit 60 of the base station may define and manage a support rate set which is a rate set supported by the base station. The support rate set may include a rate that the terminal connecting to the base station must support and an optional rate.

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

The management frame is used for managing a communication link with another terminal. As the management frame, for example, there is a beacon frame which notifies group attribute and synchronization information in order to form a wireless communication group which is a Basic Service Set (BSS) in the IEEE 802.11 standard. There are also frames etc. exchanged for authentication or for establishing communication links. In addition, a state in which a certain terminal has exchanged information necessary for performing wireless communication with another terminal is referred to as a communication link established here. Necessary information exchange includes, for example, notification of functions supported by the terminal itself (for example, support for UL-OFDMA system, various capabilities described later, etc.), negotiation for system setting, and the like. The management frame is generated by the transmission processing unit 30 based on an instruction received from the MAC/PHY management unit 60 via the MAC common processing unit 20.

In relation to the management frame, the transmission processing unit 30 has a notification unit that notifies other terminals of various information via the management frame. The notification means of the terminal as the non-base station, by transmitting the information indicating which one of the UL-OFDMA compatible terminal, the IEEE802.11n compatible terminal and the IEEE802.11ac compatible terminal is compatible with the management frame, the base The station may be notified of the type of its own terminal. The management frame includes, for example, an Association Request frame used in an association process, which is one of the procedures for the terminal to authenticate with a base station, or a Reassociation Request frame used in a rear association process. The notification means of the base station may notify the terminal of the non-base station of the information on the availability of UL-OFDMA communication via the management frame. Management frames used for this include, for example, a Beacon frame and a Probe Response frame which is a response to the Probe Request frame transmitted by the non-base station terminal. The base station may have a function of grouping a terminal group connected to its own device. The notification means of the base station may notify the group ID, which is the group identifier of the group to which each terminal belongs, via the management frame. The management frame is, for example, a Group ID Management frame. The group ID may be, for example, the group ID (6 bits) defined for DL-MU-MIMO in IEEE Std 802.11ac-2013 extended to include the case of UL-OFDMA. May be a group ID defined by another method. In addition, when the base station specifies the group and performs UL-OFDMA, if there is information necessary for determining the resource unit used by the terminal belonging to the group, the base station transmits the information via an arbitrary management frame. It may be notified (when the group is specified as described later, the terminal has a function of selecting a resource unit based on a method similar to the random backoff method).

Here, the association ID (AID) will be described. The AID is an association process (terminal identifier) of the terminal assigned from the base station in an association process for allowing the terminal to connect to the base station and exchange data frames in the BSS under the base station. Specifically, the association process transmits an Association Request frame from the terminal to the base station, transmits an Association Response frame from the base station to the terminal, and sets the terminal Status Code field in the Association Response frame to “0”, that is, success. Is a successful process. The communication capability (Capability) of the transmitting terminal is included in both the Association Request frame and the Association Response frame, so that both of the receiving sides know the communication capability of the other party. When the terminal Status Code field in the Association Response frame is “0”, that is, success, the AID is extracted from the AID field (16 bits) in the same frame and used as the AID of the destination terminal. That is, at this point, the base station has assigned the AID to the terminal, and the AID is valid for the terminal. The AID of the terminal is valid in the state where the base station is connected (associated) with the terminal. On the other hand, when the base station transmits a Disassociation frame to the terminal and the terminal receives the Disassociation frame, or when the terminal transmits a Disassociation frame to the base station, the AID of the terminal becomes null. Naturally, the AID is invalid even in a terminal that has not gone through an association process with any base station. The state in which the AID is invalid can also be called a state in which the AID is unspecified.

The reception processing unit 40 has a reception unit that receives various information from another terminal via the management frame. As an example, the receiving means of the base station may receive information on the availability of UL-OFDMA communication from a terminal as a non-base station. In addition, information about a channel width (maximum available channel width) that can be supported when the terminal is a legacy terminal (eg, a terminal compatible with the IEEE802.11a/b/g/n/ac standard) may be received. The receiving means of the terminal may receive the information on the availability of UL-OFDMA support from the base station.

The example of the information transmitted/received via the management frame described above is only an example, and various other information can be transmitted/received between terminals (including a base station) via the management frame. For example, a UL-OFDMA-capable terminal uses a resource unit or a channel, or both of which it desires to use in UL-OFDMA transmission, with a carrier-sense non-interfering channel or non-interfering resource unit, Alternatively, both of them may be selected. Then, the base station may be notified of information regarding the selected resource unit and/or channel. In this case, the base station may perform resource unit allocation for UL-OFDMA communication to each UL-OFDMA compatible terminal based on the information. Note that the channels used in UL-OFDMA communication may be all channels that can be used as a wireless communication system or some (one or more) channels.

The data frame is used to transmit data to the other terminal while the communication link is established with the other terminal. For example, data is generated in the terminal by the application operation of the user, and the data is carried by the data frame. Specifically, the generated data is passed from the higher-level processing unit 90 to the transmission processing unit 30 via the MAC common processing unit 20, and the transmission processing unit 30 puts the data in the frame body field and puts it in the frame body field. A data frame is generated by adding a MAC header. Then, the PHY processing unit 50 adds a physical header to the data frame to generate a physical packet, and the physical packet is transmitted via the analog processing unit 70 and the antenna 80. When the PHY processing unit 50 receives the physical packet, the physical layer is processed based on the physical header to extract the MAC frame (here, the data frame), and the data frame is passed to the reception processing unit 40. When receiving the data frame (recognizing that the received MAC frame is a data frame), the reception processing unit 40 extracts the information of the frame body field as data, and passes the extracted data through the MAC common processing unit 20. And passes it to the upper processing unit 90. As a result, application operations such as data writing and data reproduction occur.

The control frame is used for control when transmitting/receiving (exchange) the management frame and the data frame to/from another wireless communication device. As the control frame, for example, an RTS (Request to Send) frame and a CTS (Clear to send) that are exchanged with another wireless communication device to reserve a wireless medium before the exchange of a management frame and a data frame is started. Send) frame. Further, as another control frame, there is a delivery confirmation response frame for confirming delivery of the received management frame and data frame. Examples of the delivery confirmation response frame include an ACK (Acknowledgement) frame and a BA (BlockACK) frame. Since the CTS frame is also transmitted as a response to the RTS frame, it can be said that the frame also represents a delivery confirmation response. The CF-End frame is also one of the control frames. The CF-End frame is a frame that announces the end of CFP (Contention Free Period) or the termination of TXOP described later, that is, a frame that permits access to a wireless medium. These control frames are generated by the transmission processing unit 30. Regarding the control frame (CTS frame, ACK frame, BA frame, etc.) transmitted as a response to the received MAC frame, the reception processing unit 40 determines the necessity of transmitting the response frame (control frame), and generates the frame. It sends necessary information (type of control frame, information set in RA (Receiver Address) field, etc.) to the transmission processing unit 30 together with a transmission instruction. The transmission processing unit 30 generates an appropriate control frame based on the information necessary for generating the frame and the transmission instruction.

When transmitting a MAC frame based on CSMA/CA (Carrier Sense Multiple Access with Carrier Aviation), the MAC processing unit 10 needs to acquire an access right (transmission right) on a wireless medium. The transmission processing unit 30 measures the transmission timing based on the carrier sense information from the reception processing unit 40. The transmission processing unit 30 gives a transmission instruction to the PHY processing unit 50 according to the transmission timing, and further passes the MAC frame. In addition to the transmission instruction, the transmission processing unit 30 may also instruct the modulation scheme and the coding scheme used for transmission. In addition to these, the transmission processing unit 30 may instruct the transmission power. After obtaining the access right (transmission right), the MAC processing unit 10 obtains a time (Transmission Opportunity; TXOP) capable of occupying the medium, but is subject to restrictions such as a QoS (Quality of Service) attribute, but other wireless communication. MAC frames can be continuously exchanged with the device. In TXOP, for example, a wireless communication device transmits a predetermined frame (eg, RTS frame) based on CSMA/CA (Carrier Sense Multiple Access with Carrier Aviation), and a response frame (eg, CTS frame) is correctly transmitted from another wireless communication device. Acquired when received. When the predetermined frame is received by the other wireless communication device, the other wireless communication device transmits the response frame after a minimum frame interval (Short InterFrame Space; SIFS). Also, as a method of acquiring TXOP without using an RTS frame, for example, a data frame requesting transmission of a delivery confirmation response frame by direct unicast (a frame in which frames are concatenated as described later, or a payload is concatenated The frame may be a frame having a specified shape) or a management frame, and a delivery confirmation response frame (ACK frame or BlockACK frame) for the frame may be correctly received. Alternatively, when a frame that does not request transmission of a delivery confirmation response frame to another wireless communication device and has a Duration/ID field set to a period equal to or longer than the time required to transmit the frame is transmitted. It may be interpreted that the TXOP of the period described in the Duration/ID field is acquired from the stage of transmitting the frame.

The reception processing unit 40 manages the carrier sense information described above. This carrier sense information is based on the physical carrier sense (Physical Carrier Sense) information regarding busy/idle of the medium (CCA) input from the PHY processing unit 50 and the medium reservation time described in the received frame. It includes both virtual carrier sense (Virtual Carrier Sense) information. If either carrier sense information indicates busy, the medium is considered busy and transmission is prohibited during that time. In the IEEE 802.11 standard, the medium reservation time is described in the Duration/ID field in the MAC header. When the MAC processing unit 10 receives a MAC frame addressed to another wireless communication device (not addressed to itself), the medium is virtually busy from the end of the physical packet including the MAC frame to the medium reservation time. Judge that there is. Such a mechanism for virtually determining that a medium is busy, or a period during which a medium is virtually busy is called NAV (Network Allocation Vector). It can be said that the medium reservation time represents the length of the period for instructing the suppression of access to the wireless medium, that is, the length of the period for delaying access to the wireless medium.

Here, the MPDU may connect a plurality of MAC frames or payload portions of a plurality of MAC frames. The former is called A (Aggregated)-MPDU in the IEEE 802.11 standard, and the latter is called A (Aggregated)-MSDU (MAC service data unit). In the case of A-MPDU, a plurality of MPDUs are connected in PSDU. As the MAC frame, not only the data frame but also the management frame and the control frame are connected. In the case of A-MSDU, a plurality of data payloads MSDUs are concatenated in the frame body of one MPDU. Both A-MPDU and A-MSDU store delimiter information (length information, etc.) in a frame so that the receiving terminal can appropriately separate the connection of a plurality of MPDUs and the connection of a plurality of MSDUs. ing. Both A-MPDU and A-MSDU may be used in combination. Further, the A-MPDU may target only one MAC frame instead of a plurality of MAC frames, and in this case also, delimiter information is stored in the frame. Further, when receiving A-MPDU or the like, responses to a plurality of concatenated MAC frames are collectively transmitted. In this case, a BA (BlockACK) frame is used for the response instead of the ACK frame. In the following description and drawings, the notation of MPDU may be used, but this also includes the case of A-MPDU or A-MSDU described above.

According to the IEEE802.11 standard, a non-base station terminal joins a BSS (which is called an infrastructure BSS) mainly composed of a base station, and data frames can be exchanged within the BSS. A plurality of procedures to be followed are defined in stages. For example, there is a procedure called association, and a terminal of a non-base station transmits an association request frame to a base station to which the terminal requests a connection. After transmitting the ACK frame for the association request frame, the base station transmits an association response frame, which is a response to the association request frame.

The terminal can notify the base station of the capability of its own terminal by storing the capability of its own terminal in the association request frame and transmitting it. For example, the terminal may transmit, in the association request frame, a channel and/or a resource unit that the terminal can support, or both, and information for specifying a standard that the terminal supports. This information may be set in a frame transmitted by a procedure called reassociation for reconnecting to another base station. In this reassociation procedure, a terminal transmits a reassociation request frame to another base station that requests reconnection. The other base station transmits an ACK frame for the reassociation request frame, and then transmits a reassociation response frame that is a response to the reassociation request frame.

As the management frame, a beacon frame, a probe response frame or the like may be used in addition to the association request frame and the reassociation request frame. The beacon frame is basically transmitted by the base station, and a parameter indicating the attribute of the BSS and a parameter notifying the capability of the base station itself can be stored. Therefore, as a parameter for notifying the capability of the base station itself, the base station may add information on whether or not it is compatible with UL-OFDMA. Further, as another parameter, information on the support rate (Supported Rate) of the base station may be notified. The support rate may include a rate that is mandatory for a terminal that participates in the BSS formed by the base station and an optional rate. The probe response frame is a frame that is transmitted in response to a probe request frame received from a terminal that transmits a beacon frame. Since the probe response frame basically notifies the same content as the beacon frame, the base station notifies the terminal that has transmitted the probe request frame of its own capability even if the probe response frame is used. be able to. By performing this notification to the UL-OFDMA compatible terminal, the terminal may perform an operation of enabling the UL-OFDMA communication function of the terminal itself.

It should be noted that the terminal may notify, as the information for notifying the base station of the capability of the terminal itself, information on the rate that the terminal can execute among the support rates of the base station. However, regarding the required rate among the support rates, the terminal connected to the base station is assumed to have the ability to execute the required rate.

It should be noted that, of the information handled above, if the notification of one information determines the content of another information, the notification can be omitted. For example, consider a case in which a capability corresponding to a certain new standard or specification is defined, and if it is compatible with the standard, it is a UL-OFDMA compatible terminal. In this case, it is not necessary to explicitly notify the presence of the capability corresponding to the standard or the specification as the above-mentioned certain information and to explicitly notify that the terminal is an OFDMA-compatible terminal as the above-mentioned other information.

FIG. 4 shows a wireless communication system according to this embodiment. This system includes a base station (AP: Access Point) 100 and a plurality of terminals (STA: STA) 1 to 8. A BSS (Basic Service Set) 1 is formed by the base station 100 and the subordinate terminals 1 to 8. This system is a wireless LAN system that conforms to the IEEE 802.11 standard using CSMA/CA (Carrier Sense Multiple Access with Carrier Aviation). It should be noted that legacy terminals (IEEE 802.11a/b/g/n/ac standard compliant terminals, etc.) other than the terminal (UL-OFDMA terminal) according to the present embodiment may be present in the BSS1.

FIG. 5A shows a basic format example of a MAC frame. The data frame, the management frame, and the control frame according to this embodiment are based on such a frame format. This frame format includes each field of a MAC header (MAC header), a frame body (Frame body), and an FCS. As shown in Fig. 5B, the MAC header includes fields of Frame Control, Duration/ID, Address1, Address2, Address3, Sequence Control, QoS Control, and HT (High Throughput) control.

Not all of these fields need to be present, and some fields may not be present. For example, the Address3 field may not exist. Also, both or one of the QoS Control and HT Control fields may not be present. It is also possible that the frame body field does not exist. There may be other fields not shown in FIG. For example, the Address4 field may be further present. The RU/AID field described later may be present in the MAC header or the frame body field.

A receiver address (Receiver Address; RA) is entered in the Address 1 field, a sender address (Transmitter Address; TA) is entered in the Address 2 field, and a BSS identifier is entered in the Address 3 field according to the purpose of the frame. Either a certain BSSID (Basic Service Set IDentifier) (may be a wildcard BSSID for all BSSIDs by putting 1 in all bits) or TA is entered. However, as will be described later, the present embodiment is characterized in that the Address1 and Address2 fields are used in a method different from that described here.

In the Frame Control field, two fields such as a type (Type) and a subtype (Subtype) are set as described above. A data field, a management frame, or a control frame is roughly classified according to the Type field, and a detailed type in the classified frame, for example, a BA frame or a BAR frame in a control frame, or a management frame The Beacon frame is identified by the Subtype field. The trigger frames described below may also be distinguished by a combination of type and subtype. The trigger frame is a promising type of control frame.

The Duration/ID field describes the medium reservation time, and when a MAC frame addressed to another terminal is received, the medium is virtually busy from the end of the physical packet including the MAC frame to the medium reservation time. To determine. Such a mechanism for determining that the medium is virtually busy, or a period during which the medium is virtually busy is called NAV (Network Allocation Vector), as described above. The QoS field is used to perform QoS control in which transmission is performed in consideration of frame priority.

In the management frame, an information element (Information element; IE) to which a unique Element ID (IDentifier) is assigned is set in the Frame Body field. One or more information elements can be set in the frame body field. As shown in FIG. 6, the information element has each field of an Element ID field, a Length field, and an information (Information) field. The information element is identified by the Element ID. The information field stores the content of information to be notified, and the Length field stores the length information of the information field.

In the FCS field, FCS (Frame Check Sequence) information is set as a checksum code used for the frame error detection on the receiving side. Examples of FCS information include CRC (Cyclic Redundancy Code).

FIG. 7 shows an operation sequence example of the base station (AP) 101 according to the present embodiment and a plurality of terminals including the terminal (STA) 1 to the terminal (STA) 8. The terminals 1 to 8 are UL-OFDMA compatible terminals.

In this operation sequence example, as a premise, communication (single user communication) is individually performed on the basis of CSMA/CA between the base station and some or all of the terminals 1 to 8. In single-user communication, for example, communication is performed between a base station and a terminal on one channel having a basic channel width (for example, 20 MHz). As an example of single user communication, when the terminal holds data for uplink transmission, the access right to the wireless medium is acquired according to CSMA/CA. Therefore, when the terminal performs carrier sense during the carrier sense time (waiting time) of DIFS/AIFS[AC] and the randomly determined back-off time, and the medium (CCA) is determined to be idle, for example, Acquire the access right to transmit one frame. The terminal transmits a data frame including the data to be transmitted (more specifically, a physical packet including the data frame), and when the base station normally receives the data frame, the delivery confirmation is made SIFS after the completion of the reception of the data frame. An ACK frame (more specifically, a physical packet including an ACK frame) that is a response frame is returned. Upon receiving the ACK frame, the terminal determines that the data frame has been successfully transmitted. The data frame transmitted to the base station may be an aggregation frame (A-MPDU or the like), and the delivery confirmation response frame to which the base station responds may be a BA frame (the same applies hereinafter). Note that the DIFS/AIFS[AC] time means one of DIFS and AIFS[AC] time. When it is not QoS-supported, it indicates DIFS time, and when it is QoS-supported, it indicates AIFS [AC] time determined according to an access category (AC: Access Category) of data to be transmitted (described later).

The base station determines the start of UL-OFDMA at any timing. In this example, it is assumed that UL-OFDMA transmission is performed on the same channel as single-user communication (one channel having a basic channel width of 20 MHz). That is, it is assumed that UL-OFDMA transmission is performed using a plurality of resource units defined in a channel having a basic channel width of 20 MHz. However, it is also possible to perform UL-OFDMA transmission with other channel widths such as 40 MHz and 80 MHz.

When the base station decides to start UL-OFDMA transmission, it transmits a UL-OFDMA transmission trigger frame (more specifically, a physical packet including a trigger frame) 501. The trigger frame 501 is transmitted by a channel having the same basic channel width as the single user communication. The physical packet including the trigger frame is, for example, a physical header added to the beginning of the trigger frame. As an example, the physical header is, as shown in FIG. 8, an L-STF (Legacy-Short Training Field), an L-LTF (Legacy-Long Training Field), and an L-SIG (Legacy Signal) defined in the IEEE 802.11 standard. Field), is included. L-STF, L-LTF, and L-SIG are fields that can be recognized by terminals of legacy standards such as IEEE802.11a, and signal detection, frequency correction (propagation path estimation), and transmission rate (transmission rate), respectively. Information such as is stored. Fields other than those described here (for example, a field that a terminal of the legacy standard cannot recognize and a UL-OFDMA compatible terminal can recognize) may be included.

The trigger frame 501 may be a frame that can be received and decoded by a legacy terminal as well as a UL-OFDMA compatible terminal. It is assumed that the base station has acquired the access right according to CSMA/CA before transmitting the trigger frame. Acquisition of the access right is similar to that of the terminal described above. In the present embodiment, there are a plurality of frame formats of the trigger frame 501 and its usage method (interpretation rules), and the operation of the terminal when the trigger frame 501 is received is different depending on which one. In the description of this sequence, an example of a typical operation will be described, and an operation as a variation will be described later. Here, it is assumed that the trigger frame 501 includes, as an example, information that specifies a plurality of resource units that can be used in UL-OFDMA transmission and information that specifies a plurality of terminals that are candidates for UL-OFDMA transmission. . The information specifying the resource unit specifies all or a part of the plurality of resource units defined in the channel, for example. The information that identifies the plurality of terminals that are candidates includes, for example, at least one group ID or an identifier (AID, MAC address, or the like) of each of the plurality of terminals. Examples other than those mentioned here are possible.

The trigger frame 501 transmitted from the base station is received by the terminals 1-8. Each of the terminals 1 to 8 decodes the trigger frame 501 and determines whether the terminal itself belongs to the group having the group ID specified in the trigger frame 501. Note that the terminal receives the notification of the group ID of the group to which the terminal belongs from the base station during the association process or at any timing thereafter. Notification of correspondence between terminals other than the own terminal and the group may be received. When the own terminal belongs to the group ID specified in the trigger frame and holds the data for uplink transmission, the resource used by the own terminal from the plurality of resource units specified in the trigger frame 501. Units are selected based on a method similar to the random backoff approach. It is not necessary to select a terminal that does not hold data for uplink transmission, but it is possible to select it. The number to be selected may be determined in advance, may be designated by the trigger frame 501, or may be grasped by another method. Here, it is assumed that each terminal belonging to the above group can select at most one resource unit.

Here, it is assumed that in the trigger frame 501, n resource units 1 to n are designated as the information for identifying the resource unit. The resource units 1 to n may be all resource units defined in the channel used in UL-OFDMA or some resource units. The resource units 1 to n may be identified by RU#1 to RU#n, which are respective identifiers or numbers. A configuration in which an identifier for identifying a set of a plurality of resource units is separately defined and one or more identifiers of the set are designated in the trigger frame 501 is also conceivable. In this case, the terminal grasps available resource units from the identifier of the set.

In this example, it is assumed that the group to which the terminals 1, 3, 4, and 6 belong in common among the terminals 1 to 8 is designated, and the group to which at least one of the terminals 2, 5, 7, and 8 belongs is not designated. As an example, it is assumed that a group including terminals 1, 3, 4, and 6 and a group including terminals 2, 5, 7, and 8 are defined in the base station, and only the group ID of the former group is designated. Then, the terminals 1, 3, 4, and 6 each hold data for uplink, and all of these terminals acquire the resource unit selection right, and the resource unit 2 randomly selects from the resource units 1 to n. It is assumed that 4, 6, 7 are selected. The terminals 1, 3, 4, 6 receive data frames 511, 513, 514, 516 including data for uplink transmission after a predetermined time T1 from the completion of reception of the trigger frame 507 (more specifically, physical frames including the data frame). Packet) to the base station. The transmission of the data frames 511, 513, 514, 516 is performed using the resource units 2, 4, 6, 7 selected by the terminals 1 to 4, respectively.

The fixed time T1 is, for example, a SIFS (Short Inter-frame Space) time (=16 μs), which is a time interval between frames defined in the MAC protocol specification of the IEEE 802.11 wireless LAN, or other predefined time. Time (IFS) can be used. The fixed time T1 may be determined by the system or the specifications, or may be notified in advance by another method such as a beacon frame or other management frame. As another example, the value of the fixed time T1 may be stored in a predetermined field of the trigger frame 501, and the terminals 1 to 4 may obtain the value of the fixed time T1 from the predetermined field.

The transmission timings of the data frames transmitted by the terminals 1, 3, 4, and 6 are synchronized with each other, so that UL-OFDMA transmission is executed. When the terminal performs an operation of selecting a resource unit even though there is no data to be transmitted in the uplink, the terminal has a frame of a predetermined format, for example, a physical header and a MAC header, but a data field A null packet (null packet) that is a non-existing frame may be transmitted. Alternatively, the terminal may select the resource unit but not perform any transmission operation. When the base station receives the null packet, the terminal may determine that there is no data to be transmitted.

The base station receives data frames 511, 513, 514, and 516 (more specifically, physical packets including data frames) transmitted by OFDMA from the terminals 1, 3, 4, and 6. The base station receives the data frames 511, 513, 514, 516 in resource units 2, 4, 6, 7 respectively. Since data frames are not transmitted from any terminal in other resource units, the base station does not receive data frames.

When the base station correctly receives the data frames transmitted from the terminals 1, 3, 4, and 6, the base station transmits a delivery confirmation response frame 521 to the terminals 1, 3, 4, and 6 after a predetermined time T2 from the reception of each data frame. To do. The fixed time T2 is, for example, a SIFS (Short Inter-frame Space) time (=16 μs), which is a time interval between frames defined by the MAC protocol specification of IEEE 802.11 wireless LAN, or other predefined time. Time (IFS) can be used.

As the transmission of the delivery confirmation response frame 513, the BA frame is transmitted to each of the terminals 1, 3, 4, and 6 by the resource unit in which the data frame is received. If the data frame transmitted to the base station is not an A-MPDU but includes a normal (single) MPDU, an ACK frame may be used instead of the BA frame (note that a BA frame may be returned in the case of a normal MPDU). Is possible). Transmitting the BA (or ACK) frame in each resource unit for each of the terminals 1, 3, 4, and 6 in this way corresponds to transmitting a delivery confirmation response frame in the downlink OFDMA. In this case, each terminal receives a BA (or ACK) frame in each resource unit (a reception filter is set in advance so that signals can be received in resource unit units). Alternatively, the BA frame (or ACK frame) can be transmitted to the terminals 1, 3, 4, and 6 by downlink MU-MIMO. Downlink MU-MIMO is specified in IEEE 802.11ac.

As yet another method, a single frame including all acknowledgments for terminals 1, 3, 4, and 6 may be transmitted in the channel width band (single user transmission). In this case, this frame may be called a Multi-STA BA frame. As a specific configuration, for example, a Multi-TID BA frame defined by the IEEE 802.11 standard may be used. As an example, the BA information fields of the Multi-TID BA frame are arranged by the number of terminals, and the terminal identifier (for example, AID (Association ID) or part of AID) is set in the reserved field in the TID information subfield of each BA information field. To set. A value may be set in the Block Ack Starting Sequence Control subfield and the Block Ack Bitmap subfield of each BA information field according to the data frames 511, 513, 514, and 516 for which the delivery confirmation response should be returned as usual. RA (reception destination address) of the Multi-STA BA frame may be a multicast address or a broadcast address of a group to which the terminals 1, 3, 4, and 6 commonly belong. By doing so, the BA can be notified to a plurality of terminals in one frame. Also, a new value may be defined as a subtype of the Frame Control field.

When returning an ACK frame instead of a BA frame to the terminals 1, 3, 4, and 6, the terminal identifier is set in a part of the reserved field in the TID information subfield of each BA information field, and the remaining one is set. The bit of the field of the copy is set (set to 1). Then, when the bit is set, the Block Ack Starting Sequence Control subfield and the Block Ack Bitmap subfield are omitted (do not exist). As a result, ACKs of a plurality of terminals can be notified in one frame. As another example, a partial state operation is used, and the corresponding sequence number is represented by a Block Ack Bitmap subfield. The example described here is an example, and an existing frame other than the Multi-TID BA frame may be diverted, or a new frame may be defined instead of diverting the existing frame.

In the above description, an example in which the delivery confirmation response frame 521 is transmitted to the terminals 1, 3, 4, 6 at a time is shown, but a method of returning BA frames or ACK frames to the terminals 1, 3, 4, 6 in order is also possible. It is possible. For example, when returning BA frames in order, a BA frame is returned to any one terminal (for example, terminal 1) SIFS time after the completion of reception of a data frame, and the remaining terminals receive BAR frames from the terminals. However, the BA frame may be transmitted as a response. Alternatively, for the remaining terminals, the base station may transmit the BA frame without receiving the BAR frame and receive the ACK frame as a response. It is also possible to return the BA frame or the ACK frame by a method other than that described here.

After the transmission confirmation response frame 521 is transmitted by the base station, the same sequence may be repeated again from the transmission of the trigger frame from the base station.

In the above-described operation example, when the terminal designated by the group ID in the trigger frame has the resource unit selection right, the resource unit is randomly selected from the plurality of resource units designated in the trigger frame. As another operation, the base station may individually specify the resource unit for each terminal in the trigger frame, and the terminal specified in the trigger frame may select the resource unit specified in the trigger frame. For example, the identifiers (AID, etc.) of the terminals 1, 3, 4, 6 are designated in the trigger frame, and the identifiers of the resource units 2, 4, 6, 7 are designated individually for these terminals. As a result, the same sequence as in FIG. 7 is performed. You may make it allocate several resource units to the same terminal continuously. Also, an operation that combines both of these operations (random selection of resource units and individual designation) is possible. Also, a terminal that is not yet connected to the base station can be designated in the trigger frame as a target of UL-OFDMA. Hereinafter, a configuration example and a usage example (interpretation example) of the trigger frame 501 for realizing these operations, and operations of the base station and the terminal according to the configuration example will be described in more detail.

FIG. 9A shows a configuration example of the trigger frame 501. The RU/AID field is added to the MAC header of the MAC frame shown in FIG. 5, and some fields such as the Address3 field are deleted. However, some or all of these deleted fields may exist in the frame structure of FIG. 7. FIG. 9B shows an example in which the RU/AID field exists in the frame body field instead of the MAC header. When the RU/AID field is provided in the frame body field, if the trigger frame 501 is a management frame, it is possible to provide the RU/AID field as an information element as shown in FIG. In the case of a control frame or a data frame, the RU/AID field may be added to the frame body field in a distinguishable format. In the following description, it does not matter whether the RU/AID field is in the MAC header or the frame body field unless it is necessary to make a distinction.

FIG. 10 shows a configuration example of the RU/AID field of the trigger frame and an example of each field length. The field lengths shown here are merely examples, and other values may be used. For example, although the field length is shown here in units of octets (8 bits), it does not have to be in units of octets. “3×n” means a value obtained by multiplying 3 by n.

The RU/AID field includes n pairs (sets) of the RU field (RU_1 to RU_n) and the AID field (AID_1 to AID_n). As a basic method of using this frame format, the resource unit and the terminal to which the resource unit is assigned are specified using the RU field and the AID field. The resource unit identifier is set in the RU field, and the terminal identifier (AID in this case) of the terminal to which the resource unit is assigned is set in the AID field. As a result, a terminal is designated for each resource unit, and each terminal uses the designated resource unit. Here, the type of the frame control field is "control" or "management", and the subtype defines a new value corresponding to the trigger frame. The type may be "data" instead of "control" or "management". In this case, instead of defining the subtype to a new value, a field for notifying whether the frame is a trigger frame is separately provided in the MAC header, and a bit is set in the field to notify that the frame is a trigger frame. I don't care. The Duration/ID field specifies the period length from the end of the trigger frame where the user wants to occupy the wireless medium. For example, the time length to the end of the delivery confirmation response frame is designated. Values may be set as usual in the Sequence Control and FCS fields. A broadcast address or a multicast address may be set as RA in the Address1 field. The MAC address (BSSID) of the base station may be set as TA in the Address2 field. Note that n (the number of pairs of RU field and AID field) may be fixed or variable. In the case of being variable, a field for determining n may be provided at the beginning of the RU/AID field, or a field for notifying the end of the RU/AID field may be provided. The end notification field may be a special value that is not included in the combination of the resource unit identifier and the AID.

In the following, using a frame format having such a structure of the RU/AID field, a terminal group is designated by a group ID as described in FIG. 7, and a random backoff method is applied to a terminal group belonging to the group ID. An example is shown in which a resource unit is selected based on a method similar to, and frame transmission is performed.

(First example)
Also in this case, the identifiers of available resource units are set in the RU fields (RU_1 to RU_n). In the example of FIG. 10, there are n RU fields, and the identifiers of the corresponding resource units are set in these RU fields. On the other hand, arbitrary values are set in the n AID fields (AID_1 to AID_n) in the first example.

On the other hand, the type of the frame control field is “control” or “management”, and the subtype defines a new value corresponding to the trigger frame. The type may be "data" instead of "control" or "management". In this case, instead of defining the subtype to a new value, a field for notifying whether the frame is a trigger frame is separately provided in the MAC header, and a bit is set in the field to notify that the frame is a trigger frame. I don't care. The Duration/ID field specifies the period length from the end of the trigger frame where the user wants to occupy the wireless medium. For example, the time length to the end of the delivery confirmation response frame is designated. Values may be set as usual in the Sequence Control and FCS fields.

In the Address1 field, the group ID of the group to which the candidate terminal (terminals 1, 3, 4, 6 in the example of FIG. 7) belongs is set. Normally, RA (unicast address, broadcast address, or multicast address) is set in the Address1 field, so setting a group ID is an operation different from the normal operation. Therefore, it is necessary to notify that the group ID is set in the Address1 field. Therefore, the Address2 field is set to a value obtained by converting the Individual/Group bit (bit at the specific position) of the base station MAC address (BSSID) to 1. Normally, TA is set in the Address2 field, so it is a normal operation to set the MAC address (BSSID) of the base station. Here, in order to notify that the group ID is set in the Address1 field, a value obtained by converting the Individual/Group bit of the MAC address (BSSID) of the base station to 1 is set. The Individual/Group bit is the 8th bit of the MAC address (when transmitting the MAC address, it is transmitted in octet units from the beginning, and in each octet, the least significant bit is transmitted in order, so the Individual/Group bit transmits the MAC address. It is also the first bit when the data is processed), and the Individual/Group bit of the MAC address of the terminal (including the base station) is 0. It is 1 in the case of a broadcast address or a multicast address. Therefore, by converting this Individual/Group bit from 0 to 1, the terminal is notified that the group ID is set in the Address1 field (usually, since the transmission of the trigger frame is from the base station, The TA set in the Address2 field is the MAC address of the base station, and the fact that the Individual/Group bit is 0 is used). Therefore, the terminal can determine that the group ID is set in the Address1 field because the Individual/Group bit in the Address2 field is 1, and the source address of the trigger frame is the Individual/Group bit in the bit string of the Address2 field. It is also possible to determine that the value has been returned from 1 to 0. Therefore, as the RA when the terminal transmits the data frame, the one in which the Individual/Group bits of the bit string of the Address2 field are returned from 1 to 0 (that is, the MAC address of the base station) can be used.

Note that n (the number of pairs of RU field and AID field) may be fixed or variable. In the case of being variable, a field for determining n may be provided at the beginning of the RU/AID field, or a field for notifying the end of the RU/AID field may be provided. The end notification field may be a special value that is not included in the combination of the resource unit identifier and the AID.

The terminal that has received the trigger frame set as described above recognizes that the trigger frame has been received, for example, from the values of the type and subtype of the frame control field. Since Individual/Group in the Address2 field is 1, it is grasped that the group ID is set in the Address1 field, and the group ID set in the Address1 field is read out. It is determined whether or not the terminal itself belongs to the group indicated by the group ID. If the terminal does not belong to the group, the trigger frame is discarded and the process ends. When the terminal itself belongs to the group indicated by the group ID, the RU/AID field is confirmed, and the resource unit indicated by the identifiers set in the n RU fields is grasped as the resource unit to be used. . Ignore the n AID fields. For example, the terminal subtracts the number of resource units that are usage candidates from the back-off counter value that is randomly selected in advance, and determines that it has the right to select a resource unit when it becomes 0 or less, and randomly selects from among the resource units that are usage candidates. Select the resource unit used by the terminal. Although it is assumed here that one resource unit is selected, a plurality of resource units may be selected as described above. It doesn't matter what method you choose at random. For example, a random number generator that generates a certain number of digits may be used to specify a resource unit having a number obtained by adding 1 to the remainder value when the random number value is divided by n. In this case, the resource unit 1 is selected if the value of the remainder is zero, and the resource unit n is selected if the value of the remainder is n-1. The example described here is only an example, and of course, another method may be used. The terminal uses the randomly selected resource unit to transmit the data frame as described above. RA (value of Address1 field) of the data frame is the MAC address (BSSID) of the base station, and TA (value of Address2 field) is the MAC address of the own terminal.

According to the first example described above, only the terminals belonging to the group specified by the group ID are candidate terminals for UL-OFDMA, so that the terminals are randomly selected as compared to the case where all terminals that have received the trigger frame are candidate terminals. It is possible to reduce the possibility that resource units to be selected overlap between terminals. In addition, when the same resource unit is selected among a plurality of terminals, signal interference occurs in the resource unit in the base station, and frames from these plurality of terminals cannot be normally received.

(Second example)
The second example is different from the first example in the setting of n AID fields and the operation of the terminal. The difference from the first example will be described below. In the n AID fields, unused values or AIDs assigned to terminals are set. The “unused value as AID” is a value outside the range of AID values that can be assigned by the base station. For example, when the base station uses 14 bits of 2 octets (16 bits) to represent the AID, if the range of the AID value that can be assigned by the base station is 1 or more and 2007 or less, 2 of the AID field is set. All 14 bits (0th to 13th bits) of the octet (16 bits) are set to 0 or a value within 2008 to 16383. Fixed values (for example, "11") are set in the 14th and 15th bits. Note that the setting example of the unused value of the AID described here is similar to the method of using the reserved area of the Duration/ID field defined in the IEEE 802.11 standard (IEEE Std 802.11(TM)). -See Table 8-3 of 2012). When the terminal is made to randomly select the resource unit, an unused value is set as the AID in the corresponding AID field. On the other hand, when designating the resource unit used by the terminal, the AID assigned to the terminal is set in the corresponding AID field. When setting unused values as AIDs in all the n AID fields, the values set in these n fields may or may not be common values.

The terminal judges whether the value of the AID field is “unused value as AID” and “unused value as AID” (in the above example, the 0th to 13th bits are 0 or 2008 or more). If the 14th and 15th bits are “11”), it is determined that the resource unit is available. If the value can be used as the AID (in the above example, the 0th to 13th bits are bits representing the value within 1 to 2007, and the 14th and 15th bits are “11”), The resource unit determines whether the AID is the AID of its own terminal. If it is the AID of the own terminal, the own terminal determines that the use of the resource unit is designated by the base station. If it is not the AID of the own terminal, it is determined that the resource unit cannot be used by the own terminal. If there is a resource unit designated for the terminal, the terminal selects that resource unit. When the number of resource units required for communication is plural (H) and the specified number of resource units is less than H, only the resource units of the difference should be randomly selected from the available resource units. Good.

According to the above-described second example, it is possible to limit UL-OFDMA candidate terminals to a specific group and also to specify a resource unit to be used for each terminal. By this means, for example, when the terminal uses a plurality of resource units, some base stations can be designated by the base station and the remaining resource units can be randomly selected. Since the resource unit designated by the base station is not used by other terminals, interference between terminals at the resource unit at the base station does not occur and more reliable communication can be expected.

(Third example)
In the second example, the unused value or the AID assigned to the terminal is set in the AID field, but in this example, the unassigned value or the AID assigned to the terminal is set as the AID. The difference from the second example will be described. The unallocated value as the AID is a value of the AID within a range that the base station can allocate as the AID, in addition to the unused value as the AID, but includes an AID that has not been allocated yet. When the base station notifies each terminal of the list of terminals and AIDs, this method also enables the same operation as in the second example. That is, when the base station randomly selects a resource unit, the base station sets an unallocated value as the AID in the corresponding AID field. On the other hand, when designating the resource unit used by the terminal, the AID assigned to the terminal is set in the corresponding AID field. The terminal determines whether or not the value of the AID field is “unassigned value as AID” by using the above list, and if “unassigned value as AID”, the relevant resource unit can be used It is determined that If it is a value that has been assigned as an AID, it is determined whether the value is the AID of the own terminal, and if it is the AID of the own terminal, it is determined that the use of the relevant resource unit by the own terminal is designated by the base station. To do. If it is not the AID of the own terminal, it is determined that the resource unit cannot be used by the own terminal. If there is a resource unit designated for the terminal, the terminal selects that resource unit. When the number of resource units required for communication is plural (H) and the number of designated resource units is less than H, only the resource units of the difference should be randomly selected from the available resource units. Good.

According to the third example described above, the same effect as that of the second example can be obtained.

(Fourth example)
In the fourth example, the base station sets, in the AID field, the AID of a terminal that prohibits the use of the resource block of the terminals belonging to the group having the group ID, or an unused value as the AID. Differences from the first to third examples will be described. When it is desired to prohibit the use of a specific terminal but to permit the use of any of the remaining terminals, the AID of the prohibited terminal is set in the AID field. When permitting use of all terminals belonging to the group of the group ID, an unused value is set as the AID. As with the third example, an unassigned value may be used as the AID instead of the unused value as the AID. The terminal determines that the resource unit whose own AID is set in the AID field cannot be used by the terminal itself. It is determined that the resource unit in which an unused value (or an unassigned value as the AID) is set as the AID is available. The terminal randomly selects a resource unit used by the terminal itself from the available resource units.

According to the fourth example described above, it is possible to prohibit the use of a certain resource unit by a specific terminal, but allow other terminals to randomly select the resource unit.

(Fifth example)
The fifth example is different from the first to fourth examples in the method of notifying that the group ID is set in the Address1 field of the trigger frame.

The reason why it is necessary to notify that the group ID is set in the Address1 field is that a unicast address, a broadcast address, or a multicast address is usually set in the Address1 field and the group ID is set. Is not supposed. Therefore, it is necessary to be able to distinguish whether a group ID is set in the Address1 field or an address such as broadcast or multicast is set.

In the first to fourth examples, the Individual/Group bit of the Address2 field is converted to 1 in order to notify that the group ID is set, but in this example, the Individual/Group bit maintains 0. That is, the MAC address (BSSID) of the base station is set in the Address2 field as usual. Instead, the fact that the group ID has been set is notified to the terminal using another field. For example, the presence or absence of the group ID is set using the reserved area of the frame control field. Alternatively, the QoS field shown in FIG. 5 is also left in the trigger frame, and the presence or absence of the group ID is set in the reserved area in the QoS field. Alternatively, a new field such as a HE (High Efficiency) control field shown in FIG. 11 is provided in the MAC header, and the presence or absence of a group ID is set in the HE control field. The procedure is the same as in the first to fourth examples except that the presence/absence of the group ID is notified.

(Sixth example)
The sixth example differs from the first to fifth examples in the method of notifying that the group ID is set in the Address1 field of the trigger frame. Hereinafter, the difference from the fifth example will be mainly described. In the fifth example, in order to notify that the group ID is set, a new field is provided or the reserved area of the existing field is used. On the other hand, in the sixth example, the AID field of the RU/AID field is used. In the AID field, the above-mentioned "unused value as AID" is set in the AID field. It may be included in all AID fields, or may be included in only one or more specific AID fields, for example, the first AID field. In the sixth example, setting an "unused value as the AID" in the AID field means that the group ID is set in the Address1 field. Instead of "unused value as AID", "unassigned value as AID" may be used.

When the terminal receives a trigger frame (it recognizes that the received frame is a trigger frame depending on the type and subtype of the frame control field), it can use any AID field in the RU/AID field, or a specific one. Alternatively, the values of a plurality of AID fields are confirmed, and if the value is “unused value as AID” (or “unallocated value as AID”), it is grasped that the group ID is set in the Address1 field. Alternatively, check the values of all the AID fields in the RU/AID field, and if all are "unused values as AIDs" (or "unassigned values as AIDs"), the group ID is set in the Address1 field. You may know that it is set. When the terminal recognizes that the group ID is set in the Address1 field, it reads the value set in the Address1 field and determines whether the terminal belongs to the group having the group ID indicated by the value. When the own terminal belongs to the group, the resource unit indicated by the value set in each RU field in the RU/AID field is specified as the resource unit that can be used by the own terminal. The resource unit used by the own terminal is randomly selected from the resource units specified as described above. The subsequent operation is the same as in the first example.

(Seventh example)
In the seventh example, the format shown in FIG. 12 is used as the format of the trigger frame. The difference from the format example shown in FIG. 9 is that the RU/AID field has been replaced with an AID notification field (AID Notification Field). The AID notification field includes n AID fields (AID_1, AID_2,... AID_n). Each AID field is associated with a predetermined resource unit. For example, AID_1 is associated with resource unit 1, AID_2 is associated with resource unit 2, and so on. Which AID field is associated with which resource unit may be notified from the base station to each terminal in advance, or may be predetermined by the system or the specifications. The setting method of each AID field and other fields is the same as the examples described above. Also, the operation of the terminal when the trigger frame is received is the same as that of the above examples except that the operation of checking the RU field is unnecessary.

(Eighth example)
In the eighth example, the format of the trigger frame shown in FIG. 13 is used. The difference from the format example shown in FIG. 9 is that the RU/AID field is replaced with an RU notification field. The RU notification field includes n RU fields. Similar to the first to sixth examples, an identifier of a resource unit that can be used in UL-OFDMA is set in each RU field. The setting method of the other fields is the same as in the first example or the fifth example.

For example, if setting is performed according to the first example, a group ID is set in the Address1 field, and an Individual/Group bit of the MAC address of the base station is replaced with 0 to 1 in the Address2 field. The type of the frame control field is “control” or “management”, and the subtype uses a newly defined value for the trigger frame. Alternatively, the type may be "data". In this case, instead of defining the subtype to a new value, a field for notifying whether the frame is a trigger frame is separately provided in the MAC header, and a bit is set in the field to notify that the frame is a trigger frame. I don't care.

Further, when setting according to the fifth example, a group ID is set in the Address1 field and a MAC address (BSSID) of the base station is set in Address2. Further, the presence or absence of a group ID is set in the reserved area of the frame control field or the reserved area in the QoS field (see FIG. 5). Alternatively, for example, a HE (High Efficiency) control field shown in FIG. 11 is provided in the MAC header, and the presence or absence of a group ID is set in the HE control field. The setting of the frame control field is the same as in the first example and the like.

When the terminal receives the trigger frame (for example, when the terminal recognizes that the received frame is the trigger frame according to the type and subtype of the frame control field), it knows the available resource unit from each RU field in the RU notification field. Then, a resource unit is randomly selected from the grasped resource units. The subsequent operation is similar to that of the first example and the like.

(Ninth example)
In the ninth example, similar to the first to sixth examples, the format of the trigger frame shown in FIG. 9 is used, but the usage method of the Address1 field and the AID field is different. In this example, a broadcast address or a multicast address is set in the Address1 field. The frame in which the broadcast address is set is a frame that is received by each of the terminals 1 to 8 addressed to itself. When the multicast address is set, it is assumed that the terminals 1 to 8 are targets of the multicast address here, and the frame is received by the terminal itself. However, it is also possible to use a multicast address of a group to which some of the terminals 1 to 8 do not belong. A group ID is set in each AID field in the RU/AID field. In order to notify that the group ID is set in each AID field, the Address2 field is set with the Individual/Group bit of the MAC address of the base station replaced with 0 to 1. In the other example described above, the Individual/Group bit is converted from 0 to 1 in order to notify that the group ID is set in the Address1 field. However, in this example, the group ID is set in the AID field. The Individual/Group bit is converted to 1 in order to notify that it is present. In each AID field, the group ID of the UL-OFDMA target group is set as a common value. FIG. 14 shows how a group ID is set in each AID field. The length of the group ID is set to 2 octets in the example of FIG. 14 from the point of the AID field that originally sets the AID, but if 1 octet is sufficient to express the group ID (for example, if the group ID is 6 The AID field length may be changed, such as by making it a one-octet field (for example, in the case of bits). In this case, information for distinguishing from the format of FIG. 10 may be set in the head of the RU/AID field, the reserved area of the existing field as described above, the field to be newly added, or the like.

When the terminal receives the trigger frame, the terminal determines from the address of the Address1 field of the received frame that the frame should be received by itself, and recognizes that the frame is a trigger frame based on the type and subtype of the frame control field. Since the Individual/Group bit in the Address2 field is 1, it is understood that the group ID in the AID field is set. The terminal reads the group ID from at least one AID field and determines whether the group ID indicates the group of the terminal itself. When the group of the own terminal is not shown, the own terminal determines that it is not the target of this UL-OFDMA and discards the frame. On the other hand, when the group ID indicates the group ID of the own terminal, the resource unit identifier is read from each RU field to grasp the available resource unit. Then, a resource unit is randomly selected from the grasped available resource units. The subsequent operation is similar to that of the first example and the like.

(Tenth example)
The difference from the ninth example will be described below. In the ninth example described above, a group ID having a common value is set in each AID field, but in the tenth example, it is permitted to set a different group ID for each AID field. The base station determines an available group for each resource unit, and sets the group ID of the group in the AID field corresponding to the RU field.

The terminal that has received the trigger frame detects the group ID set in each AID field and determines whether or not the terminal itself belongs to the group ID. The terminal recognizes only the resource unit designated by the RU field corresponding to the AID field in which the group ID to which the terminal belongs is set as the resource unit that can be used by the terminal. Then, a resource unit is randomly selected from the grasped available resource units. The subsequent operation is similar to that of the first example and the like.

(Eleventh example)
In the 9th example and the 10th example described above, in order to notify that the group ID is set in each AID field, the Individual/Group bit of the MAC address of the base station is replaced from 0 to 1 in the Address 2 field. Set things. On the other hand, in the eleventh example, the fact that the group ID is set in each AID field is notified by another method.

In the eleventh example, a group ID is set in each AID field in a reserved area of an existing field such as a reserved area of a frame control field or a newly defined field such as the HE control field shown in FIG. Information (group ON information) for notifying that there is a change is set. Alternatively, if an unused area (reserved area) exists in the RU field (for example, if all resource units can be identified by the upper 6 bits, the last 2 bits area), group ON information is set in the area. May be. When the group ON information is not set, the base station sets an AID in each AID field (in this case, as described above, UL-OFDMA that specifies a terminal for each resource unit is performed). In this case, the base station sets, in place of the group ON information, information (group OFF information) notifying that the AID is set in the above-mentioned area or new field. In the Address2 field, the MAC address (BSSID) of the base station is set as usual. A broadcast or multicast address is set in the Address1 field as in the ninth and tenth examples.

The terminal receiving the trigger frame judges whether the group ON information is set in the reserved area of the above-mentioned existing field or the newly defined field, and if the group ON information is set, in the AID field. Understand that a group ID (rather than an AID) is set. The subsequent operation is similar to that of the ninth example or the tenth example.

(Twelfth example)
In the twelfth example, the fact that the group ID is set in each AID field is notified by a method different from the ninth to eleventh examples. In the twelfth example, a broadcast or multicast address is set in the Address1 field as in the ninth and tenth examples, and the MAC address (BSSID) of the base station is set in the Address2 field as usual. To set.

In the twelfth example, the setting of the predetermined area in each AID field is changed depending on whether the group ID is set or the AID is set. For example, if the base station can express the AID using 14 bits of 2 octets (16 bits), the 14th bit of the 0th to 13th bits is the value of the AID or the group ID (bit length shorter than the AID. 2 bits of the 14th and 15th bits are used to identify whether the group ID is set or the AID is set. For example, when setting the AID, the 2 bits are set to “11” (group OFF information), and when setting the group ID, the 2 bits are set to “00”. The bit settings shown here are examples, and other bit settings may be used.

The terminal receiving the trigger frame confirms the predetermined area (the 143rd and 15th bits in this example) of each AID field, and if group ON information (for example, “00”) is set, the group is set in the AID field. Understand that the ID is set. When the group OFF information (for example, “11”) is set, it is grasped that the AID is set in the AID field. The operation after understanding that the group ID is set is the same as in the ninth example or the tenth example.

(Thirteenth example)
In the first to twelfth examples, there are two types of frame use patterns, one for setting the group ID and the other for not setting the group ID. When setting the group ID, the Individual/Group bit of the Address2 field is set to 1, or the group ID is set in the reserved area of the existing field, the newly defined field, or the predetermined area of the AID field. I set information such as being present (group ON information). On the other hand, in the thirteenth example, the group ID field is defined by default in the frame format. FIG. 15 shows an example of the frame format in this case. A group ID field has been added between the Sequence Control field and the RU/AID field. The group ID field length is 1 octet, but is not limited to this. For the RU/AID field, for example, the same configuration as that shown in FIG. 10 can be used. An arbitrary value may be set in the AID field as in the first example (when the terminal does not need to read the AID field).

Alternatively, when a specific resource unit is specified for a specific terminal among terminals belonging to the group specified by the group ID field, the specific ID is specified in the AID field corresponding to the RU field for specifying the specific resource unit. The AID of the terminal may be set. Then, an unused value as the AID or an unassigned value as the AID may be set in the AID field corresponding to the RU field that specifies the resource unit that can be used by any terminal belonging to the group. ..

The AID set in each AID field may be a partial AID (similar to the other examples described above). The partial AID is a part of the AID, and it is assumed that the partial AID does not overlap at least between terminals belonging to the same group. The partial AID may be defined in the IEEE 802.11 standard. By using partial AID instead of AID, the AID field length can be shortened. For example, the AID field length can be changed from 2 octets to 1 octet. In this case, the size of the RU/AID field can also be changed from 3×n to 2×n.

The broadcast or multicast address may be set in the Address1 field, and the MAC address (BSSID) of the base station may be set in the Address2 field as usual. The setting of the frame control field is also the same as in the first to twelfth examples.

The terminal receiving the trigger frame determines whether or not the terminal itself belongs to the group specified in the group ID field, and if it belongs to the group, it judges from the value set in each RU field set in the RU/AID field. Understand available resource units. Then, a resource unit is randomly selected from the grasped resource units based on the above-mentioned operation. The subsequent operation is similar to other operation examples. When the terminal determines that the terminal does not belong to the group specified in the group ID field, the terminal is set to the sleep mode (power saving mode) for any time such as the period specified in the Duration/ID field. You may make a transition. The operation of transitioning to the sleep mode can be similarly applied to the first to thirteenth examples.

Alternatively, when the self terminal belongs to the group specified by the group ID field, the AID (or partial AID) set in the AID field is examined to determine whether the self terminal is specified. When the own terminal is specified, the own terminal determines to use the resource unit set in the corresponding RU field. If the number of resource units specified for the own terminal is less than H (integer of 1 or more), which is the number of resource units required for communication, an unused value for AID or an unallocated value for AID Specifies the RU field corresponding to the set AID field, and grasps the resource unit designated by the RU field as an available resource unit. Then, less than H resource units may be randomly added from the grasped available resource units.

(Fourteenth example)
In the fourteenth example, the frame format shown in FIG. 16 is used as the frame format of the trigger frame. The difference from FIG. 15 is that the RU/AID field is replaced with the RU notification field. The structure of the RU notification field is similar to that of FIG. 13, and has a form in which the AID field is omitted from the RU/AID field. By using this format, the same operation as when ignoring the AID field in the thirteenth example can be realized with a shorter trigger frame length.

(Fifteenth example)
In the fifteenth example, the frame format shown in FIG. 17 is used as the frame format of the trigger frame. The difference from FIG. 16 is that the RU notification field does not exist. When using this format, it is assumed that the resource unit that can be used in UL-OFDMA has been determined in advance, and the base station has notified each terminal in advance, or has been determined in advance by the system or specifications. This makes it possible to realize a mechanism for performing UL-OFDMA by randomly assigning resource units to each terminal with a trigger frame having a shorter frame length.

(Sixteenth example)
In the above description, the terminal that has been connected to the base station and has been assigned an AID is the target of UL-OFDMA, but a terminal that is not connected to the base station and has not been assigned an AID, It is also possible to specify as a target of UL-OFDMA in the trigger frame. In this case, a certain group ID is defined for a terminal whose AID is not specified. Therefore, the terminal already connected to the base station does not belong to this group ID. The base station generates and transmits the trigger frame in which this group ID is set based on any of the first to fifteenth examples described so far. The AID-unassigned terminal (terminal not connected to the base station) that received the trigger frame determines that its own terminal belongs to this group ID. The terminal may be notified in advance of the notification of the group ID from the base station by a beacon frame or the like, or the group ID may be determined by the system or specifications. The corresponding terminal randomly selects a resource unit as described above. At this time, the sizes of the available resource units may be equal. The terminal can transmit the association request frame in the uplink with the selected resource unit (in this case, the base station simultaneously receives the association request frame from a plurality of terminals). The association request frame is an example, and another frame such as a reassociation request frame or a probe request frame may be used.

Further, in order to realize the similar operation, an unused value as the AID may be set in the AID field of any of the formats described above, instead of using the group ID for the terminal for which the AID is not specified. .. In this case, unlike the first to fifteenth examples up to now, the unused value as the AID means that a terminal for which the AID is not specified (a terminal not connected to the base station) is specified. The terminal for which the AID has not been specified has previously recognized the range of the AID (for example, 1 to 2007) in the system or the specifications, and a value outside this range is determined to be unused as the AID. A terminal that has not been assigned an AID (a terminal that is not connected to a base station) that has received the trigger frame indicates that its own terminal has been designated if an unused value is set as the AID in any of the AID fields. to decide. Then, the terminal can randomly select a resource unit and can perform uplink transmission of a frame such as an association request frame with the selected resource unit.

UL-OFDMA in which terminals without AID designation and terminals with AID designation described in the first to fifteenth examples coexist is also possible. In this case, the 16th example can be easily realized by combining with any one or more of the 1st to 15th examples.

(17th example)
A group ID may be provided for a terminal that is performing power saving, and this may be specified in the trigger frame. For example, it is assumed that a terminal performing power saving may be required to periodically send a specific frame to the base station. For example, it can be considered that the PS-Poll is requested to be sent periodically. Therefore, at the timing, the base station may transmit a trigger frame in which the group ID of the terminal group that is performing power saving is specified, and receive a specific frame from a plurality of terminals. Each terminal does not need a process such as carrier sense and access right acquisition by back-off, as compared with a normal single-user transmission, and thus power consumption can be further reduced.

(Eighteenth example)
The frame formats shown in FIG. 9 to FIG. 17 described above are examples, and other fields may further exist in the trigger frame. For example, there may be a field for setting information that specifies the packet length (PPDU length) of a physical packet transmitted by UL-OFDMA. Information specifying the MCS (modulation coding method) or transmission rate used in UL-OFDMA may be set. The packet length, the MCS, or both of them may be common to all terminals belonging to the group designated by the group ID, or may be designated individually for each terminal belonging to the group. Alternatively, the MCS may be designated for each resource unit. The field for setting the information described here may be any position in the trigger frame. For example, it may be present in the HE Control field as shown in FIG. 11, may be present in the frame body field, or may be present in the RU/AID field. The example described here is an example, and there may be fields for setting various kinds of information in addition to the above.

(Combination between the first to eighteenth examples)
The first to eighteenth examples described above can be realized independently, and two or more may be arbitrarily combined as long as the operation does not conflict. For example, by combining the thirteenth example and the fourth example, in the thirteenth example, the AID of the terminal that is prohibited from using the resource block may be set in the AID field. Other combinations are of course possible.

FIG. 18 shows a flowchart of an example of the operation of the base station according to the embodiment of the present invention. After deciding the start of UL-OFDMA at any timing, the base station selects the individual designation method for individually designating each terminal or the group designation method for designating a group as the designation method of the target terminal of UL-OFDMA. It is determined (S101). Note that the method may be determined before the UL-OFDMA start is determined, or may be determined in advance in any one of them.

When the individual designation method is determined (NO in S102), an individual terminal that performs UL-OFDMA this time is selected from the OFDMA-compatible terminals that are connected to the base station, and the resource unit to be assigned to each terminal is determined ( S103). Any method may be used to select individual terminals. For example, the presence/absence of the UL-OFDMA request may be collected from each terminal in advance, and the terminal having the request may be selected. Alternatively, the terminal having the largest data amount may be preferentially selected or the terminals having the same data amount may be selected based on the transmission data amount in each terminal. Alternatively, the terminal may be selected from the terminals belonging to the same group. At this time, items such as the presence/absence of a request for UL-OFDMA transmission for each terminal belonging to each group and the amount of transmission data may be taken into consideration as a criterion for selecting a group. Alternatively, the terminals or groups may be selected by round robin, or the terminals or groups may be selected at random. Alternatively, select a terminal having data that is estimated to have the same or similar size as the data to be transmitted next, or a terminal having the same data generation cycle or a similar data generation cycle (terminal having a generation cycle within a certain value). , Or a predetermined number of terminals having the closest generation cycle). Alternatively, the channel response (spatial channel characteristics) with each terminal may be grasped in advance, and a combination of terminals with small spatial correlation (small interference) may be selected based on the channel response. Note that the number of terminals to be selected is less than or equal to the maximum number of resource units that can be used, but when using the above-described OFDMA & MIMO scheme, the number of terminals greater than or equal to the maximum number of resource units is also possible. When the lower limit of the number of terminals to be selected is set, the number of terminals equal to or larger than the lower limit may be selected. The terminal selection example described here is merely an example, and the terminal may be selected by a method other than the method described here.

Also, the resource unit allocation method may be arbitrary. For example, when all resource units have the same bandwidth and one resource unit is assigned to each terminal, any one may be assigned to each terminal. Further, when there are resource units with a plurality of bandwidths, a resource unit with a larger bandwidth may be assigned to a terminal with a larger amount of data for transmission. Further, when allocating a plurality of resource units to one terminal, resource units arranged continuously in the frequency domain may be selected, or resource units arranged discontinuously may be selected. ..

The band used in UL-OFDMA uplink transmission may be determined in advance by the system or specifications, or may be determined when the base station performs UL-OFDMA. Alternatively, it may be determined by a method other than that described here.

The base station sets the identifier (AID or the like) of the selected terminal and the identifier of the resource unit assigned to the terminal in a predetermined field of the trigger frame (S104). The predetermined fields depend on the format used, and in the case of the format of FIG. 10, they are the RU field and the AID field in the RU/AID field. A broadcast address or a multicast address is set as RA in the Address1 field. Further, the MAC address (BSSID) of the own station is set in the Address2 field. A value for a trigger frame may be set in the type field and subtype field of the frame control field. The resource unit identifier may be a unique value among a plurality of bands, such as 20 MHz, 40 MHz, 80 MHz, or may allow the same identifier to be used in different bands. When allowing the use of the same identifier in different bands, in addition to the resource unit identifier, information for identifying the band to be used is notified in the trigger frame (for example, HE Control field in FIG. 11) or used in advance. It suffices to notify the terminal of the band to be used.

After generating the trigger frame, the base station acquires an access right to the wireless medium according to CSMA/CA, and transmits a trigger frame (more specifically, a physical packet including the trigger frame) based on the acquired access right (S105). .. The trigger frame is transmitted by, for example, a channel having a basic channel width (for example, 20 MHz) that allows legacy terminals to transmit and receive. The band used in UL-OFDMA uplink transmission is the band in which the trigger frame is transmitted, and when the uplink transmission band is 20 MHz, this is the same as the band in which the trigger frame is transmitted. When the band of the uplink transmission is 40 MHz, the transmission of the trigger frame may be transmitted by the two 20 MHz wide channels within the 40 MHz. Further, when the band of the uplink transmission is 80 MHz, the trigger frame may be transmitted on each of four 20 MHz wide channels within the 80 MHz. These states are shown in FIG. The contents of the trigger frame may all be the same. You may return to step S101 or S102 after step S105.

On the other hand, when determining the group designation method, the base station selects a group that allows UL-OFDMA this time from one or more groups generated by classifying connected OFDMA-compatible terminals (S106). .. Any method may be used to select the group. For example, the presence/absence of a request for UL-OFDMA may be collected from each terminal in advance, and a group including a terminal with a request may be selected. Alternatively, a group including a terminal having the largest data amount may be selected based on the transmission data amount at each terminal, or a group in which the terminals having the same data amount most exist may be selected. Alternatively, the group may be selected by round robin, or the group may be selected at random. Alternatively, select the group that has the largest number of terminals that have data that is estimated to have the same or similar size as the data to be transmitted next, or the terminals that have the same data generation cycle or the data generation cycle that is close (the generation cycle is constant). It is also possible to select a group that has the largest number of terminals included within the value or a predetermined number of terminals having the closest occurrence cycle. It should be noted that one group is assumed here to be selected, but a plurality of groups can be selected as described above. The group selection example described here is merely an example, and the group may be selected by a method other than the method described here.

The band used in UL-OFDMA uplink transmission may be determined in advance by the system or specifications, or may be determined when the base station performs UL-OFDMA. Alternatively, it may be determined by a method other than that described here.

The base station sets the group ID of the selected group in a predetermined field of the trigger frame (S107). The predetermined field depends on the format to be used and its usage, and is, for example, the RA field (Address1 field) in the case of the format shown in FIG. In the Address2 field, the Individual/Group bit of the MAC address (BSSID) of the local station is inverted from 0 to 1. A value for a trigger frame may be set in the type field and subtype field of the frame control field. Settings may be made by methods other than those described here, and formats other than those shown in FIG. 10 may be used. Since the details have been described above, further description will be omitted. Further, the base station may set information for identifying the band to be used in the trigger frame (for example, HE Control field of FIG. 11), may notify in advance in another frame, or may use it. The bandwidth may be predetermined by the system or specifications. Alternatively, the notification of the band to be used may be implicitly notified according to the channel (band) in which the trigger frame is received. For example, when a channel with a basic width of 20 MHz is used for uplink transmission, a trigger frame is transmitted on that channel as shown in FIG. 19 described above, and when a channel with a 40 MHz width is used, it is included in the 40 MHz. The trigger frame is transmitted on each of the two channels of 20 MHz width, and when the channel of the 80 MHz width is used, the trigger frame is transmitted on each of the four channels of 20 MHz width included in the 80 MHz. The terminal on the receiving side determines that uplink transmission is possible on the channel (band) in which the trigger frame is received. If the terminal side succeeds in receiving the trigger frame on some channels but fails to receive on another channel, select the resource unit included only in the successfully received channel (band). The resource units to be used may be limited.

After generating the trigger frame, the base station acquires an access right to the wireless medium according to CSMA/CA, and transmits a trigger frame (more specifically, a physical packet including the trigger frame) based on the acquired access right (S105). .. Details of step S105 are as described above. You may return to step S101 or S102 after step S105.

In the description of the group designation method of FIG. 18, a group may be selected, and terminals may be selected and resource units may be assigned. In this case, the group ID is set in the trigger frame, and the set of the identifier (AID etc.) of the selected terminal and the identifier of the resource unit is set, so that the resource unit is specified in the selected terminal. Good. The terminal to be selected may be a terminal belonging to the selected group or may be selected from a group other than the selected group. In addition, by selecting a terminal that prohibits the implementation of UL-OFDMA in the group and setting the identifier of the selected terminal in the trigger frame, the selected terminal is prevented from selecting the resource unit and performing the uplink transmission. You can The operations described here are merely examples, and various modifications of the operations are possible to realize the above-described first to seventeenth examples and combinations thereof.

FIG. 20 shows a flowchart of an example of the operation of the terminal according to the embodiment of the present invention. When the terminal receives the trigger frame transmitted from the base station (S201), based on the information set in the trigger frame, an individual designation method of individually designating each terminal or a group designation method of designating a group is selected. It is determined which is designated (S202). The determination method differs depending on the format of the trigger frame and the usage method thereof. For example, when the Individual/Group bit of the Address2 field is 1, it is determined to be the group designation method, and when it is 0, it is determined to be the individual designation method. Alternatively, it is determined based on a predetermined field in which information for identifying the group designation method or the individual designation method is set. It is also possible to adopt a configuration in which the determination is made by a method other than the method described here. The details are as described above.

When the individual designation method is designated (NO in S202), it is determined whether or not the own terminal is designated as a target terminal of UL-OFDMA (S203). For example, when the AID of the self terminal is set in the AID field, it is determined that the self terminal is designated. When the own terminal is designated, the resource unit assigned to the own terminal is specified (S204). For example, the resource unit designated in the RU field corresponding to the AID field in which the AID of the own terminal is set is specified as the resource unit assigned to the own terminal. The terminal generates a frame such as a data frame for uplink transmission, and transmits the frame in the specified resource unit after a fixed time after the reception of the trigger frame is completed (S205). When conditions such as the transmission packet length (PPDU length) and MCS are specified in the trigger frame, the frame is generated and transmitted so as to satisfy the conditions.

On the other hand, when the group designation method is designated (YES in S202), the group ID is read from the predetermined field of the trigger frame, and it is determined whether or not the terminal itself belongs to the group indicated by the group ID (S206). The predetermined field in which the group ID is set differs depending on the format of the trigger frame and the usage thereof, but for example, the group ID is set in the RA field (Address1 field). Alternatively, a configuration in which the group ID is set in the AID field, or a configuration in which the group ID is set in the HE Control field in FIG. 11 is also possible. The details are as described above. When the own terminal belongs to the above group, the resource unit is randomly selected from a plurality of candidate resource units (S207). Here, it may be determined between step S206 and step S207 whether there is a right to select a resource unit. For example, the number of resource units to be used is subtracted from the back-off counter value randomly selected in advance, and if it becomes 0 or less, the selection right is acquired, and the process proceeds to step S207. On the other hand, when it is greater than 0, the selection right is not acquired and the operation of this flow is ended or the process returns to step S201. The plurality of candidate resource units are designated by the RU field of the trigger frame or the like. If a plurality of group IDs are set in the trigger frame and different candidate resource units are specified for each group ID, the candidate resource unit associated with the group ID to which the own terminal belongs is selected. Identify. Alternatively, the plurality of candidate resource units may be determined in advance by the system, specifications, or the like. Alternatively, when identification information for identifying a set of a plurality of candidate resource units is set in the trigger frame, the set identification information and correspondence information that associates the identification information with the resource unit group ( A resource unit that is a candidate may be specified based on a table or the like). The corresponding information may be notified from the base station in advance. The number of randomly selected resource units may be predetermined, or information specifying the number of resources to be selected may be set in the trigger frame. The terminal generates a frame such as a data frame for uplink transmission, and transmits the frame in a randomly selected resource unit after a fixed time after the reception of the trigger frame is completed (S205). When conditions such as the transmission packet length (PPDU length) and MCS are specified in the trigger frame, the frame is generated and transmitted so as to satisfy the conditions.

In addition, when it is determined in step S202 that the group ID is designated, in addition to determining whether the terminal belongs to the above group, whether the resource unit is individually designated for the terminal is determined. A configuration for confirming is also possible. In this case, the terminal shall use the specified resource unit even if it belongs to the above group. In other words, another terminal randomly selects a resource unit that is a candidate excluding the resource unit when the resource unit designated for the terminal exists. Even when the own terminal belongs to the group, if it is designated as a terminal subject to UL-OFDMA prohibition, resource unit selection and uplink transmission are not performed. When the prohibition target terminal is specified for each resource unit, when selecting a resource unit at random, the resource unit other than the specified resource unit is randomly selected. These details are as described above. The operations described here are merely examples, and various modifications of the operations are possible to realize the above-described first to seventeenth examples and combinations thereof.

As described above, according to the present embodiment, efficient communication is performed by specifying a resource unit for each terminal when the presence/absence of an uplink request and the like can be grasped with high accuracy. By specifying by the group ID, it is possible to appropriately suppress the number of terminals that are transmission candidates, reduce the possibility that a plurality of terminals use the same resource unit at the same time, and thereby suppress the deterioration of resource efficiency. Also, when UL-OFDMA is performed when the presence or absence of a power saving terminal and the presence/absence of a request for uplink transmission are not sufficiently grasped, individual terminals can be designated by specifying a group ID. It can be expected that the resource utilization efficiency will be higher than when specifying. Especially, when the number of terminals belonging to the group is larger than the number of terminals designated individually, this effect is considered to be enhanced. However, if the number of terminals is too large, the probability of collision between terminals in the resource unit increases.Therefore, the number of terminals and resource units belonging to a group should be set so that the number of resource units is sufficiently large compared to the number of terminals belonging to You may adjust the relationship between the numbers. As an example, the number of resource units is adjusted so that the number of resource units can be sufficiently large with respect to the number of terminals belonging to the same group ID. At least the number of resource units is made larger than the number of terminals belonging to the group ID. For example, the number of resource units may be set to 2^(the number of terminals belonging to the group ID)-1 or larger (for example, it is assumed that the terminal selects one resource unit). If the number of terminals belonging to the group ID is 4, the number of resource units is set to 15 (=2^4-1) or more. As described above, it may be combined with another method that limits the number of terminals that can access the resource unit among terminals belonging to the same group. Further, in this embodiment, the same frame format (such as FIG. 10) can be used for the individual designation method and the group designation method.

In this embodiment, a plurality of different trigger frames of the same format (for example, a resource unit is individually designated for each terminal, and a resource unit used by the terminal by designating a group ID is randomly generated on the terminal side. Although it has been shown that the trigger frame is used, the frame format of the trigger frame does not matter at all.

A difference between a configuration in which a terminal designated by a group ID performs transmission using a resource unit randomly selected and a Restricted Access Window (RAW) operation of IEEE 802.11ah will be described in the present embodiment. In RAW operation, when one time slot is used as a resource unit, a terminal is designated and assigned or a group identifier is assigned to the time slot. From the time slot boundary, each terminal tries to access by EDCA (Enhanced Distributed Channel Access) based on CSMA/CA (even when the terminal is designated). On the other hand, in the present embodiment, a plurality of resource units are prepared in the frequency domain and a terminal is designated for each, or a group (a plurality of terminals) indicated by a group identifier is assigned to these resource units collectively. .. Then, each terminal randomly selects one of a plurality of resource units in the frequency domain, and transmits the frame after a fixed time from the completion of reception of the trigger frame. Therefore, in RAW operation of IEEE 802.11ah, by performing EDCA based on CSMA/CA, a collision avoidance function works in each terminal, but in this embodiment, this function does not work. Therefore, in this embodiment, it is more important to adjust the number of resource units in the frequency domain with respect to the number of terminals expected to transmit as described above in order to avoid the occurrence of collision as much as possible. The group ID described above is an example, and other configurations are possible. For example, the group ID may be a multicast address. It is also possible to use AID as the group ID. At that time, as the AID, an unused value, that is, a value outside the range in which the AID can be allocated (a value other than 1 to 2007) is used as the conventional application allocated by the base station to the associated terminal. For example, AID 0 may be used to point to a terminal group that is not associated.

(Second embodiment)
FIG. 21 is a functional block diagram of a base station (access point) 400 according to the second embodiment. This access point includes a communication processing unit 401, a transmission unit 402, a reception 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 the wired I/F 405. The communication processing unit 401 has the same function as the MAC processing unit 10 and the MAC/PHY management unit 60 described in the first embodiment. The transmission unit 402 and the reception unit 403 have the same functions as the PHY processing unit 50 and the analog processing unit 70 described in the first embodiment. The network processing unit 404 has the same function as the upper processing unit 90 described in the first embodiment. Here, the communication processing unit 401 may internally have a buffer for exchanging data with the network processing unit 404. This buffer may be a volatile memory such as SRAM or 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 higher-level communication processing such as TCP/IP and UDP/IP above the MAC layer and processing of the application layer. The operation of the network processing unit may be performed by software (program) processing by a processor such as a CPU, hardware, or 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 RF integrated circuits that transmit and receive frames. The communication processing unit 401 and the network processing unit 404 may be configured by one integrated circuit (one chip). The portions of the transmitting unit 402 and the receiving unit 403 that perform processing in the digital region and the portions that perform processing in the analog region may be configured by different chips. Further, the communication processing unit 401 may execute higher-level communication processing of the MAC layer such as TCP/IP and UDP/IP. The number of antennas is four here, but it is sufficient if at least one antenna is provided.

The memory 406 stores the data received from the server 407, the data received by the receiving unit 402, and the like. The memory 406 may be, for example, a volatile memory such as SRAM or 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 external to 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 by wireless. In this case, a wireless I/F may be used instead of the wired I/F 405.

The server 407 is a communication device that receives a data transfer request for requesting data transmission and returns a response including the requested data, and may be, for example, an HTTP server (Web server) or an FTP server. 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.

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 this 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, the destination port number, etc. are confirmed. When the packet data 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 It is confirmed whether it is cached (stored) in the memory 406. The memory 406 stores a table in which a URL (or its reduced expression, for example, a hash value or an alternative identifier) is associated with data. Here, the fact that data is cached in the memory 406 is expressed as the presence of cache data in the memory 406.

When the cache data does not exist in the memory 406, the network processing unit 404 sends 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 from the server 407 a packet which is a response to the data transfer request. The network processing unit 404 recognizes from the IP header of the packet received via the wired I/F 405 that the packet is addressed to the STA, and passes the packet to the communication processing unit 401. The communication processing unit 401 executes MAC layer processing and the like for this packet, and the transmission unit 402 executes physical layer processing and the like, and transmits a packet addressed to the STA from the antennas 42A to 42D. Here, the network processing unit 404 stores the data received from the server 407 in the memory 406 as cache data in association with the URL (or its reduced expression).

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 the 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 (destination port number of the packet transmitted by the communication terminal). Therefore, from the perspective of the STA, it looks as if it is communicating with the server 407. The communication processing unit 401 executes MAC layer processing and the like for this packet, and the transmission unit 402 executes physical layer processing and the like, and transmits a packet addressed to the STA from the antennas 42A to 42D.

By such an operation, 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 this embodiment. A general cache proxy that acquires data from the server 407 instead of the STA, caches the data in the memory 406, and responds to the data transfer request for the same data from the cache data in the memory 406. For example, there is no problem with another operation.

Although the base station having the cache function has been described in the present embodiment, a terminal (STA) having the cache function can be realized with the same block configuration as in FIG. In this case, the wired I/F 405 may be omitted. (Variations listed here)
(Third Embodiment)
FIG. 22 shows an example of the overall configuration of a terminal or base station. This configuration example is an example, and the present embodiment is not limited to this. The terminal or base station 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 the first embodiment. The wireless LAN module 148 includes a host interface, and is connected to the host system 149 via the host interface. 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, a configuration in which the wireless LAN module 148 is mounted on the board by soldering or the like and is connected to the host system 149 via the wiring of the board is also possible. The host system 149 communicates with an external device 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 higher layer protocols. 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 device. It may be an adapter, set top box, gateway, printer server, mobile access point, router, enterprise/service provider access point, portable device, handheld device, etc.

FIG. 23 shows a hardware configuration example of a wireless LAN module. This configuration is applicable regardless of whether the wireless communication device is installed in a terminal of a non-base station or a base station. That is, it can be applied as an example of a specific configuration of the wireless communication apparatus shown in FIG. In this configuration example, at least one antenna 247 is provided. When a plurality of antennas are provided, a plurality of sets of a transmission system (216, 222-225), a reception system (232-235), a PLL 242, a crystal oscillator (reference signal source) 243, and a switch 245 are arranged corresponding to each antenna. Each set may be connected to the control circuit 212. The PLL 242, the crystal oscillator 243, or both of them correspond to the oscillator according to the present embodiment.

The wireless LAN module (wireless communication device) includes a baseband IC (Integrated Circuit) 211, an RF (Radio Frequency) IC 221, 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 IC 211 and the RF IC 221 may be formed on the same substrate. Moreover, the baseband IC 211 and the RF IC 221 may be configured by one chip. The DAC 216 and/or the ADC 217 may be arranged in the RF IC 221 or may be arranged in another IC. Further, either or both of the memory 213 and the CPU 215 may be arranged in an IC different from the baseband IC.

The memory 213 stores data to be exchanged with the host system. Further, the memory 213 stores information notified to the terminal or the base station, information notified from the terminal or the base station, or both of them. Further, the memory 213 may store a program necessary for the execution of 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 a host system. The interface may be any of 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 performs processing of the MAC layer and processing of the physical layer. The baseband circuit 212, the CPU 215, or both of them 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 may include 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 physical layer processing, such as physical header addition, encoding, encryption, and modulation processing, on the frame to be transmitted. For example, two types of digital baseband signals (hereinafter, digital I signal and digital Q signal) are used. Signal).

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

The RF IC 221 is, for example, an RF analog IC or 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), a balun 235, a mixer 233, and a filter 232. Some of these elements may be located on the baseband IC 211 or another IC. The filters 222 and 232 may be band pass filters or low pass filters. The RF IC 221 is coupled to the antenna 247 via the switch 245.

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 of them to generate a signal having a constant frequency in synchronization with the phase of the input signal. The PLL 242 includes a VCO (Voltage Controlled Oscillator), and performs feedback control using the VCO based on the oscillation signal input from the crystal oscillator 243 to obtain the signal of the constant frequency. The generated signal having a constant frequency is input to the mixers 223 and 233. The PLL 242 corresponds to an example of an oscillator 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 into a radio frequency by using a signal of a constant frequency supplied from the PLL 242. The preamplifier (PA) amplifies the radio frequency analog I signal and analog Q signal generated by the mixer 223 to a desired output power. The balun 225 is a converter for converting a balanced signal (differential signal) into an unbalanced signal (single end signal). The RF IC 221 handles balanced signals, but the balun 225 converts these signals because unbalanced signals are handled from the output of the RF IC 221 to the antenna 247.

The switch 245 is connected to the balun 225 on the transmitting side during transmission, and is connected to the balun 234 or the RF IC 221 on the receiving side during reception. The control of the switch 245 may be performed by the baseband IC 211 or the RF IC 221, or another circuit that controls the switch 245 exists 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 from the antenna 247 to the space as radio waves.

The antenna 247 may be a chip antenna, an antenna formed by wiring on a printed 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 at which demodulation is possible while keeping noise low. The balun 235 performs unbalanced-balanced conversion on the signal amplified by the low noise amplifier (LNA) 234. The mixer 233 down-converts the reception signal converted into the balanced signal by the balun 235 into a base band using a signal of a constant frequency input from the PLL 242. More specifically, the mixer 233 has means for generating carrier waves that are 90° out of phase with each other based on the signal of a constant frequency input from the PLL 242, and the received signals converted by the balun 235 are 90° apart from each other. Quadrature demodulation is performed using a carrier wave having a phase shift, and an I (In-phase) signal having the same phase as the received signal and a Q (Quad-phase) signal having a 90° phase delay from this are generated. The filter 232 extracts a signal of a desired frequency component from these I signal and Q signal. The I signal and the 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 I signal into a digital I signal and the Q signal into a digital Q signal. Note that there may be a case where only one system of signal is received without quadrature demodulation.

When a plurality of antennas are provided, as many ADCs as the number of antennas may be provided. The baseband circuit 212 performs physical layer processing such as demodulation processing, error correction code processing, and physical header processing based on the digital I signal and digital Q signal to obtain a frame. The baseband circuit 212 performs MAC layer processing on the frame. Note that the baseband circuit 212 may be configured to perform TCP/IP processing when TCP/IP is mounted.

(Fourth Embodiment)
24A and 24B are perspective views of a wireless communication terminal according to the fourth embodiment. The wireless communication terminal in FIG. 24A is a notebook PC 301, and the wireless communication terminal in FIG. 24B is a mobile terminal 321. Each corresponds to one mode of a terminal (including a base station). The notebook PC 301 and the mobile terminal 321 are equipped with wireless communication devices 305 and 315, respectively. As the wireless communication devices 305 and 315, the wireless communication devices installed in the terminals (including base stations) described above can be used. The wireless communication terminal equipped with the wireless communication device is not limited to the notebook PC and the mobile terminal. For example, 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 adapter, set top box, gateway, It can also be installed in printer servers, mobile access points, routers, enterprise/service provider access points, portable devices, handheld devices, etc.

Further, the wireless communication device mounted on the terminal (including the base station) can also be mounted on the memory card. FIG. 25 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 body 332. The memory card 331 uses the wireless communication device 335 for wireless communication with an external device (a wireless communication terminal, a base station, or both of them). Note that, in FIG. 25, the description of other elements (for example, memory) in the memory card 331 is omitted.

(Fifth Embodiment)
The fifth embodiment includes a bus, a processor unit, and an external interface unit in addition to the configuration of the wireless communication device according to any of the above-described embodiments. The processor unit and the external interface unit are connected to the buffer via the bus. Firmware operates in the processor unit. As described above, by including the firmware in the wireless communication device, the function of the wireless communication device can be easily changed by rewriting the firmware. The processor unit in which the firmware operates may be a processor that performs the process of the communication processing device or the control unit according to the present embodiment, or another processor that performs the process related to the function expansion or change of the process. Good. The processor unit in which the firmware operates may be provided in the base station or the wireless communication terminal according to the present embodiment, or both of them. Alternatively, the processor unit may be included in an integrated circuit in a wireless communication device installed in a base station or an integrated circuit in a wireless communication device installed in a wireless communication terminal.

(Sixth Embodiment)
The sixth embodiment includes a clock generation unit in addition to the configuration of the wireless communication device according to any of the above-described embodiments. The clock generation unit generates a clock and outputs the clock from the output terminal to the outside of the wireless communication device. As described above, by outputting the clock generated inside the wireless communication device to the outside and operating the host side by the clock output to the outside, the host side and the wireless communication device side can be operated in synchronization. It will be possible.

(Seventh embodiment)
The seventh embodiment includes a power supply unit, a power supply control unit, and a wireless power feeding unit in addition to the configuration of the wireless communication device according to any of the above-described embodiments. 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. As described above, by providing the wireless communication device with the power supply, the power consumption can be controlled by controlling the power supply.

(Eighth Embodiment)
The eighth embodiment includes a SIM card in addition to the configuration of the wireless communication device according to any of the above-described embodiments. The SIM card is connected to, for example, the MAC processing unit 10, the MAC/PHY management unit 60, or the control unit 112 in the wireless communication device. In this way, by providing the wireless communication device with the SIM card, the authentication process can be easily performed.

(Ninth Embodiment)
The ninth embodiment includes a moving image compression/decompression unit in addition to the configuration of the wireless communication device according to any of the above-described embodiments. The moving image compression/decompression unit is connected to the bus. As described above, by providing the moving picture compression/expansion unit in the wireless communication device, it becomes possible to easily transmit the compressed moving picture and decompress the received compressed moving picture.

(Tenth Embodiment)
The tenth embodiment includes an LED unit in addition to the configuration of the wireless communication device according to any of the above-described embodiments. The LED unit is connected to at least one of the MAC processing unit 10, the MAC/PHY management unit 60, the transmission processing circuit 113, the reception processing circuit 114, and the control unit 112, for example. In this manner, by providing the wireless communication device with the LED unit, it becomes possible to easily notify the user of the operating state of the wireless communication device.

(Eleventh Embodiment)
The eleventh embodiment includes a vibrator unit in addition to the configuration of the wireless communication device according to any of the above-described embodiments. The vibrator unit is connected to at least one of the MAC processing unit 10, the MAC/PHY management unit 60, the transmission processing circuit 113, the reception processing circuit 114, and the control unit 112, for example. As described above, with the configuration in which the vibrator unit is provided in the wireless communication device, it becomes possible to easily notify the user of the operating state of the wireless communication device.

(Twelfth Embodiment)
The twelfth embodiment includes a display in addition to the configuration of the wireless communication device (the wireless communication device of the base station, the wireless communication device of the wireless communication terminal, or both) according to any of the above-described embodiments. The display may be connected to the MAC processing unit of the wireless communication device via a bus (not shown). By thus providing the display and displaying the operating state of the wireless communication device on the display, the operating state of the wireless communication device can be easily notified to the user.

(Thirteenth Embodiment)
In the present 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 wireless LAN frame interval will be described.
[1] Frame Type in Communication System Generally, as described above, the frames handled by the wireless access protocol in the wireless communication system are roughly classified into three frames, that is, a data frame, a management frame, and a control frame. It is divided into types. These types are usually indicated by a header section commonly provided between frames. As a method of displaying the frame type, one field may be made to be able to distinguish three types, or two fields may be made to be able to be distinguished. 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 of the MAC frame. The data frame, the management frame, or the control frame is roughly classified by the Type field, and the detailed classification of the roughly classified frames, for example, the Beacon frame in the management frame is identified by 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 a frame used for setting communication with another wireless communication device, a frame for releasing a communication link (that is, disconnecting a connection), and a frame related to a power saving operation in the wireless communication device. ..

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

The control frame is a frame used for control when transmitting/receiving (exchanging) a data frame to/from another wireless communication device. When the wireless communication device receives the data frame or the management frame, the response frame transmitted for confirming 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 the IEEE 802.11 standard (including the extended standard such as the above-mentioned IEEE Std 802.11ac-2013), there is an association process as one of the procedures for establishing a connection, and an Association Request frame used in the process. Since the Association Response frame is a management frame, and the Association Request frame and the Association Response frame are unicast management frames, the wireless communication terminal on the receiving side is requested to transmit the ACK frame, which is a response frame. Is the control frame.

[2] Method of disconnecting connection between wireless communication devices There are an explicit method and an implicit method for disconnecting (release) the connection. As an explicit method, one of the wireless communication devices that have established a connection transmits a frame for disconnection. In the IEEE 802.11 standard, a Deauthentication frame corresponds to this and is classified as a management frame. Usually, the wireless communication device on the side of transmitting the frame for disconnecting the connection disconnects at the time of transmitting the frame, and the wireless communication device on the side of receiving the frame for disconnecting the connection receives the frame. judge. After that, if the wireless communication terminal is a non-base station, it returns to the initial state in the communication phase, for example, the state of searching for a BSS to be connected. When a connection between a wireless communication base station and a certain wireless communication terminal is disconnected, for example, if the wireless communication base station has a connection management table for managing wireless communication terminals that join the own BSS, the connection management is performed. Information related to the wireless communication terminal is deleted from the table. For example, when the wireless communication base station assigns an AID to each wireless communication terminal that joins its own BSS at the stage of allowing the connection in the association process, the holding information associated with the AID of the wireless communication terminal that disconnected the connection. May be deleted, and the AID may be released and assigned to another newly added wireless communication terminal.

On the other hand, as an implicit method, a frame transmission (transmission of a data frame and a management frame, or a response frame to a frame transmitted by the self device) is detected from a wireless communication device of a connection partner which has established a connection for a certain period of time. If there is not, the disconnection of the connection state is determined. There is such a method, in the situation where the disconnection is determined as described above, there is a physical distance such that the wireless signal cannot be received or decoded due to the communication distance from the wireless communication device of the connection destination. This is because it is possible that a wireless link cannot be secured. That is, it is not possible to expect reception of a frame for disconnecting the connection.

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 for the frame is not received until the desired retransmission period elapses, the frame is retransmitted. The first timer is stopped upon receipt of the acknowledgment frame for the frame.

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 (within the communication range) (in other words, whether the wireless link can be secured). A management frame for transmitting the management frame is transmitted, and 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 started. Similar to the first timer, the second timer also retransmits until the second timer expires unless it receives a delivery confirmation response frame to the frame, and when the second timer expires, determines that the connection has been disconnected. .. A frame for disconnecting the connection may be transmitted when it is determined that the connection has been disconnected.

Alternatively, the third timer is started when a frame is received from the wireless communication device of the connection partner, and the third timer is stopped each time a frame is newly received from the wireless communication device of the connection partner, and is restarted from the initial value. When the third timer expires, a management frame for confirming 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) is transmitted, as described above. At the same time, a second timer (for example, a retransmission timer for management frame) that limits the retransmission period of the frame is started. Also in this case, if the delivery confirmation response frame to the frame is not received until the second timer expires, it is retransmitted, and if the second timer expires, it is determined that the connection is disconnected. Also in this case, the frame for disconnecting the connection may be transmitted at the stage when it is determined that the connection is 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 as the second timer here, but a different timer may be used.

[3] Access Method of Wireless LAN System For example, there is a wireless LAN system that is supposed to communicate or compete with a plurality of wireless communication devices. In the IEEE 802.11 wireless LAN, CSMA/CA (Carrier Sense Multiple Access with Carrier Aviation) is a basic 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 plurality of wireless communication devices grasping the transmission of the wireless communication device simultaneously transmit, and as a result, , Radio signals collide and frame transmission fails. By grasping the transmission of a certain wireless communication device and waiting a random time from the end of the transmission, the transmissions by the plurality of wireless communication devices that grasp the transmission of the wireless communication device are stochastically distributed. Therefore, if there is one wireless communication device that subtracts the earliest time from the random times, frame transmission by the wireless communication device succeeds and frame collision can be prevented. Since the acquisition of the transmission right is fair among the plurality of wireless communication devices based on the random value, the method that adopts Carrier Avidance is suitable for sharing the wireless medium between the plurality of wireless communication devices. be able to.

[4] Frame Interval of Wireless LAN The frame interval of the IEEE 802.11 wireless LAN will be described. Frame interval used in IEEE802.11 wireless LAN, distributed coordination function interframe space (DIFS), arbitration interframe space (AIFS), point coordination function interframe space (PIFS), short interframe space (SIFS), extended interframe space (EIFS) , Reduced interframe space (RIFS) and the like.

In the IEEE 802.11 wireless LAN, the definition of the frame interval is defined as the continuous period in which the carrier sense idle should be confirmed and opened before transmission, and the strict period from the previous frame is not discussed. Therefore, in the description of the IEEE802.11 wireless LAN system, the definition will be followed. In the IEEE802.11 wireless LAN, the waiting time at the time of random access based on CSMA/CA is the sum of the fixed time and the random time, and it can be said that the definition is made in order to clarify the fixed time.

DIFS and AIFS are frame intervals used when attempting to start frame exchange in a contention period in which the wireless communication device competes with another wireless communication device based on CSMA/CA. The DIFS is used when there is no distinction of the priority according to the traffic type, and the AIFS is used when the priority according to the traffic type (Traffic Identifier: TID) is provided.

Since the operations related to DIFS and AIFS are similar, hereinafter, AIFS will be mainly used for description. In the IEEE 802.11 wireless LAN, access control including start of frame exchange is performed in the MAC layer. Further, in the case of supporting QoS (Quality of Service) when data is passed from the upper layer, the traffic type is notified together with the data, and the data is classified into priorities 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 value of AIFS is provided for each access category.

PIFS is a frame interval for enabling access with priority over other competing wireless communication devices, and has a shorter period than any of the values of DIFS and 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 burst after once acquiring an access right. EIFS is a frame interval activated when frame reception fails (when the received frame is determined to be in error).

The RIFS is a frame interval that can be used when a plurality of frames are continuously transmitted in a burst to the same wireless communication device after once obtaining the access right. Request frame is not requested.

Here, FIG. 26 shows an example of frame exchange in the contention period based on random access in the IEEE 802.11 wireless LAN.

It is assumed that, when a request for transmitting a data frame (W_DATA1) is generated in a certain wireless communication device, the medium is recognized as busy medium as a result of carrier sense. In this case, the AIFS of 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. As a result of carrier sense, when the medium is not busy, that is, when the medium is recognized as idle, a fixed time AIFS is opened from the time when carrier sense is started, and the data frame W_DATA1 is communicated with. Send to.

The random time is a pseudo-random integer derived from a uniform distribution in a contention window (CW) given by 0 to an integer, multiplied by a slot time. Here, the product of the CW and the slot time is called the CW time width. The initial value of CW is given by CWmin, and the value of CW is increased until it reaches CWmax each time it is retransmitted. Both CWmin and CWmax have a value for each access category as in 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 on the wireless medium is completed. A response frame (W_ACK1) is transmitted SIFS after the time point. Upon receiving W_ACK1, the wireless communication device that has transmitted W_DATA1 transmits the next frame (eg, W_DATA2) SIFS time after the end of occupation of the physical packet containing W_ACK1 on the wireless medium if the transmission burst time limit is met. can do.

AIFS, DIFS, PIFS and EIFS are functions of SIFS and slot time, but SIFS and slot time are specified for each physical layer. Further, parameters such as AIFS, CWmin, and CWmax whose values are provided for each access category can be set for each communication group (Basic Service Set (BSS) in IEEE 802.11 wireless LAN), but default values are set. .

For example, in the standardization of 802.11ac, it is assumed that SIFS is 16 μs and slot time is 9 μs, whereby PIFS is 25 μs, DIFS is 34 μs, and the frame interval of the access category BACKGROUND (AC_BK) in AIFS has a default value of 79 μs. The default frame interval of BEST EFFORT (AC_BE) is 43 μs, the default frame interval 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, 15 and 31, and AC_VO, 7 and 15. The EIFS is basically the sum of the time length of the response frame in the case of transmitting SIFS and DIFS at the lowest required physical rate. In addition, in a wireless communication device that can efficiently take EIFS, the occupied time length of a physical packet that carries a response frame to the physical packet that activates EIFS is estimated, and the sum of SIFS, DIFS, and the estimated time thereof may be used. it can.

The terms used in this embodiment should be broadly interpreted. For example, the term "processor" may include a general purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, etc. In some situations, “processor” may refer to an application specific integrated circuit, field programmable gate array (FPGA), programmable logic circuit (PLD), etc. "Processor" may refer to a combination of processing devices, such as multiple microprocessors, a combination of DSP and microprocessor, one or more microprocessors cooperating with a DSP core.

As another example, the term "memory" may include any electronic component capable of storing electronic information. "Memory" is random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electrically erasable PROM (EEPROM), non-volatile It may refer to random access memory (NVRAM), flash memory, magnetic or optical data storage, which are readable by the processor. A memory may be said to be in electrical communication with the processor if the processor reads and/or writes information to the memory. The memory may be integral to the processor and again, the memory can be said to be in electrical communication with the processor.

Note that the frame described in each embodiment may refer not only to what is called a frame in the IEEE 802.11 standard, but also to what is called a packet such as Null Data Packet. When expressing that a base station transmits or receives a plurality of frames or a plurality of Xth frames, these frames or the Xth frame may be the same (for example, the same type or the same content) or different. .. An arbitrary value can be put in X depending on the situation. The plurality of frames or the plurality of Xth frames may be transmitted or received at the same time, or may be transmitted or received at timings different in time. Further, when expressing that the first frame, the second frame, etc. are transmitted or received at different points in time, the expressions, “first, second, etc.” are merely expressions for distinguishing the frames, and The type and content of the frame does not matter.

The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements within a range not departing from the gist of the invention in an implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, the constituent elements of different embodiments may be combined appropriately.

Claims (9)

A wireless communication device,
A transmitter for transmitting a first frame including at least one set of a first field and a second field;
A receiver for receiving at least one second frame transmitted in response to the first frame;
Equipped with
One of a first group identifier and a second group identifier is selectively set in the first field of the at least one set, and the first group identifier is at least one unit connected to the wireless communication device. Of the first wireless communication terminal, the second group identifier represents at least one second wireless communication terminal not connected to the wireless communication device,
First information designating a resource unit for random access is set in the second field of the at least one set,
The first frame is
The wireless communication terminal of the group identifier designated by the first field of the at least one set is caused to randomly determine whether to transmit the second frame, and the wireless communication terminal determines to transmit the second frame. The second frame is transmitted via at least one of resource units specified in the second field that is paired with the first field in which the group identifier is set in the at least one set. Let
Wireless communication device. The wireless communication device conforms to the IEEE 802.11 standard,
The first wireless communication terminal is a wireless communication terminal assigned an AID by the wireless communication device,
The second wireless communication terminal is a wireless communication terminal that is not assigned an AID by the wireless communication device.
The wireless communication device according to claim 1. The first group identifier and the second group identifier are selected from AIDs other than the AID that can be assigned to the wireless communication terminal connected to the wireless communication device, among a plurality of AIDs in the IEEE 802.11 standard. And
The AID of the first group identifier and the AID of the second group identifier are different from each other.
The wireless communication device according to claim 1. The AID of the first group identifier and the AID of the second group identifier are selected from 0 or a value larger than 2007.
The wireless communication device according to claim 2. The wireless communication device according to claim 1, further comprising at least one antenna. A wireless communication method executed by a wireless communication device, comprising:
Transmitting a first frame including at least one set of a first field and a second field,
Receiving at least one second frame transmitted in response to the first frame;
One of a first group identifier and a second group identifier is selectively set in the first field of the at least one set, and the first group identifier is at least one unit connected to the wireless communication device. Of the first wireless communication terminal, the second group identifier represents at least one second wireless communication terminal not connected to the wireless communication device,
First information designating a resource unit for random access is set in the second field of the at least one set,
The first frame randomly causes the wireless communication terminal of the group identifier specified in the first field of the at least one set to determine whether to transmit the second frame, and the wireless communication terminal receives the second frame. Via at least one of the resource units specified in the second field paired with the first field in which the group identifier is set in the at least one set, Send the second frame
Wireless communication method. A wireless communication device,
A receiver for receiving a first frame including at least one set of a first field and a second field;
A control unit,
And a transmitter,
One of a first group identifier and a second group identifier is selectively set in the first field of the at least one set, and the first group identifier is at least one unit connected to a base station. Of the first wireless communication terminal, the second group identifier represents at least one second wireless communication terminal not connected to the base station,
First information designating a resource unit for random access is set in the second field of the at least one set,
When the wireless communication device is not connected to the base station, the control unit identifies the first field in which the second group identifier is set in the at least one set, and the wireless communication device is When connected to a base station, identifies the first field in which the first group identifier is set in the at least one set,
Randomly decides whether to send the second frame,
When it is determined to transmit the second frame, the transmission unit, in the at least one set, at least one of resource units designated by the second field that is paired with the identified first field. The second frame is transmitted after a lapse of a first time from the reception of the first frame via
Wireless communication device. Further comprising at least one antenna
The wireless communication device according to claim 7. A wireless communication method executed by a wireless communication device, comprising:
Receiving a first frame including at least one set of a first field and a second field;
One of a first group identifier and a second group identifier is selectively set in the first field of the at least one set, and the first group identifier is at least one unit connected to a base station. Of the first wireless communication terminal, the second group identifier represents at least one second wireless communication terminal not connected to the base station,
First information designating a resource unit for random access is set in the second field of the at least one set,
When the wireless communication device is not connected to the base station, the first field in which the second group identifier is set is specified in the at least one set, and the wireless communication device is connected to the base station. The first field in which the first group identifier is set in the at least one set,
Randomly decides whether to send the second frame,
If it is decided to transmit the second frame, in the at least one set, via at least one of the resource units specified in the second field that is paired with the identified first field, Transmitting the second frame after a lapse of a first time from the reception of the first frame,
Wireless communication method.

Images