JP2017022702A - Radio device and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform uplink frequency multiplex transmission by efficiently using communication resources.SOLUTION: A radio device as one aspect of the present invention comprises: a transmission unit for transmitting a first frame that includes information specifying a plurality of frequency components and instructs a plurality of radio communication terminals to perform frequency multiplex transmission; and a reception unit for receiving a second frame by using at least one frequency component among the plurality of frequency components. The first frame has any one format of a first format that specifies the terminal identifier of each of the plurality of radio communication terminals by associating it with at least one of the plurality of frequency components, and a second format that specifies the group identifier of a group including the plurality of radio communication terminals.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a wireless device and a wireless communication method.

  Consider frequency multiplex communication in which transmissions addressed to a plurality of terminals or receptions from a plurality of terminals are simultaneously performed using different frequency components for each wireless communication terminal (hereinafter, “terminal”) as a communication resource. Here, a frequency component is defined as a resource unit including one or a plurality of subcarriers, and transmission to a plurality of terminals or reception from a plurality of terminals is simultaneously performed using the resource unit as a minimum unit communication resource. Consider an Orthogonal Frequency Division Multiple Access (OFDMA) system (OFDMA; Orthogonal Frequency Division Multiple Access). Simultaneous transmission from the base station to a plurality of terminals corresponds to downlink OFDMA (DL-OFDMA) transmission, and simultaneous transmission from the plurality of terminals to the base station corresponds to uplink OFDMA (UL-OFDMA) transmission.

  When performing uplink OFDMA (UL-OFDMA) communication, it is conceivable 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 performing 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. In this method, there is a problem in that the use efficiency of communication resources decreases when the terminal transitions to the sleep mode or when the terminal does not request uplink transmission. As another method, there is a trigger frame in which only a resource unit to be used is specified without specifying a terminal. In this case, the terminal that has received the trigger frame selects a 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, the possibility of selecting the same resource unit increases. If a plurality of terminals transmit frames using the same resource unit, the base station cannot receive the frames normally.

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

  Embodiments of the present invention are directed to performing uplink frequency division multiplexing using communication resources efficiently.

  A radio apparatus according to an aspect of the present invention includes a transmission unit that includes information designating a plurality of frequency components and transmits a first frame that instructs execution of frequency multiplex transmission by a plurality of radio communication terminals, and the plurality of frequencies A receiving unit that receives 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 that is specified in association with at least one and a second form that designates a group identifier of a group to which the plurality of wireless communication terminals belong.

The functional block diagram of the radio | wireless communication apparatus which concerns on embodiment of this invention. The figure for demonstrating allocation of a resource unit. The figure for demonstrating the various structures of a resource unit. The figure which shows the radio | wireless communication group containing a base station and a some terminal. The figure which shows the example of a basic format of a MAC frame. The figure which shows the format example of an information element. The figure which shows the example of the operation | movement 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 example format of a trigger frame. The figure which shows the further another format example of a trigger frame. The figure which shows the further another format example of a trigger frame. The figure which shows the further another format example of a trigger frame. The figure which shows the further another format example of a trigger frame. The figure which shows the further another format example of a trigger frame. The figure which shows the further another format example 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 example of whole structure 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 based on embodiment of this invention. The figure which shows an example of the frame exchange of 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, known as wireless LAN standards, are all incorporated herein by reference. And

(First embodiment)
FIG. 1 is a functional block diagram of the wireless communication apparatus according to the first embodiment. This wireless communication apparatus can be implemented in a wireless communication base station (hereinafter referred to as a base station or an access point) or a wireless communication terminal (hereinafter referred to as a terminal) that communicates with the base station. Since the base station has basically the same communication function as the terminal except that it mainly has a relay function, it is a form of the terminal. In the following description, the term “terminal” may refer to a base station unless it is particularly necessary to distinguish between the two.

  In the present embodiment, it is assumed that uplink OFDMA (UL-OFDMA: Orthogonal Frequency Division Multiple Access) transmission is performed from a plurality of terminals to a base station. In UL-OFDMA, one or a plurality of subcarriers are allocated 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 a minimum unit of resources for communication. FIG. 3 shows resource units (RU # 1, RU # 2,... RU # K) reserved in a continuous frequency region of one channel (denoted as channel M here). A plurality of subcarriers orthogonal to each other are arranged in channel M, and a plurality of resource units including one or a plurality of continuous subcarriers are defined in channel M. One or more subcarriers (guard subcarriers) may be arranged between resource units, but guard subcarriers are not essential. Each subcarrier in the channel may be given a number for identifying the subcarrier. The bandwidth of one channel is, for example, 20 MHz, 40 MHz, 80 MHz, 160 MHz, but is not limited thereto. A plurality of 20 MHz channels may be combined into one channel. Depending on the bandwidth, the number of subcarriers or resource units in the channel may be different. Uplink OFDMA communication is realized by a plurality of terminals using different resource units simultaneously.

  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 example of the arrangement pattern of resource units in one channel. The horizontal direction along the plane of 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 in FIG. . FIG. 3C shows an example in which resource units of three types of bandwidths are arranged. The resource unit (RU # 12-1, RU # 12-2) has the largest bandwidth, and the resource unit RU # 12- (L-1) has the same bandwidth, resource unit (RU) as in FIG. # K-1, RU # K) has the same bandwidth as FIG.

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

  Note that the number of resource units used by each terminal is not limited to a specific value, and one or more resource units may be used. When the terminal uses a plurality of resource units, a plurality of resource units that are continuous in frequency may be used, or a plurality of resource units in remote locations may be allowed to be used.

  Although subcarriers in one resource unit are assumed to be continuous in the frequency domain, a resource unit may be defined from a plurality of subcarriers arranged discontinuously. The number of channels used in uplink OFDMA communication is not limited to one, and it is the same as that of channel M in another channel (refer to channel N in FIG. 2) arranged at a position distant from channel M in the frequency domain. Resource units may be secured and resource units in both channel M and channel N may be used. The channel M and channel N may have the same or different resource unit arrangement method. As an example, the bandwidth of the channel N is 20 MHz, 40 MHz, 80 MHz, 160 MHz, or the like as described above, but is not limited thereto. It is possible to use more than two channels. Note that the channel M and the channel N may be considered as a single channel.

  A terminal that implements OFDMA has at least a channel with a basic channel width (20 MHz channel width if a terminal that supports IEEE802.11a / b / g / n / ac standard is a legacy terminal) of a legacy terminal that is subject to backward compatibility. Thus, it is assumed that a physical packet including a frame can be received and decoded (including demodulation and decoding of an error correction code). Carrier sense is performed in units of basic channel width. The carrier sense includes CCA (Clear Channel Assessment) busy / idle physical carrier sense (Physical Carrier Sense) and virtual carrier sense (Virtual Carrier Sense) 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, such as the latter, or a period during which a medium is virtually busy is called a NAV (Network Allocation Vector). Note that the carrier sense information based on CCA or NAV performed for each channel 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 all idle.

  In addition to the resource unit based OFDMA described above, OFDMA based on channel is also possible. The OFDMA in this case may be particularly called MU-MC (Multi-User Multi-Channel). In MU-MC, a base station allocates a plurality of channels (one channel width is 20 MHz, for example) to a plurality of terminals, and simultaneously uses the plurality of channels to simultaneously transmit to or receive from a plurality of terminals. Do. In the OFDMA described below, a resource unit-based OFDMA is assumed, but an embodiment of a channel-based OFDMA can be realized by performing necessary replacement such as replacing the resource unit described below with a channel.

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

  In the following description, a terminal having the capability of implementing UL-OFDMA may be referred to as a UL-OFDMA compatible terminal (or simply an OFDMA compatible terminal). A terminal that does not have the capability may be referred to as a legacy terminal. When the capability of performing UL-OFDMA communication can be switched between enabled (disabled) and disabled (disabled), a terminal with the enabled capability may be considered as an OFDMA compatible terminal.

  As shown in FIG. 1, a wireless communication device mounted on a terminal (a non-base station terminal and a base station) includes an upper processing unit 90, a MAC processing unit 10, a PHY (Physical) processing unit 50, 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, a pair of N analog processing units and N antennas are connected, but the present invention is not necessarily limited to this configuration. For example, the number of analog processing units may be one, and two or more antennas may be commonly connected to the 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 processing related to communication with other terminals (including base stations). The analog processing unit 70 corresponds to, for example, a form of a wireless communication unit or an RF (Radio Frequency) integrated circuit that transmits and receives signals via the antenna 80. 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 functions 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. May be. The software may be stored in a storage medium such as a ROM or RAM, a hard disk, or an SSD, read by a processor, and executed. The memory may be a volatile memory such as SRAM or DRAM, or a nonvolatile 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 host 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 upper application layer. However, 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. You may connect with a wired infrastructure via the high-order process part 90. FIG. 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 nonvolatile 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 host 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 / reception in the MAC layer. The MAC common processing unit 20 is connected to the host 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 at the MAC layer. The reception processing unit 40 performs reception processing at 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 the MAC operation and the PHY operation in the wireless communication apparatus.

  The analog processing unit 70 includes an analog / digital and digital / analog (AD / DA) converter and an RF (Radio Frequency) circuit. The analog processing unit 70 converts the digital signal from the PHY processing unit 50 into an analog signal having a desired frequency. A high-frequency analog signal transmitted from the antenna 80 and received from the antenna 80 is converted into a digital signal. Here, AD / DA conversion is performed by the analog processing unit 70, but a configuration in which the PHY processing unit 50 is provided with an AD / DA conversion function is also possible.

  The wireless communication apparatus according to the present embodiment includes (integrates) the antenna 80 as a constituent element in one chip, so that the mounting area of the antenna 80 can be reduced. Further, in the wireless communication apparatus according to the present embodiment, as illustrated 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 apparatus in FIG. 1 can be reduced in size. Of course, the wireless communication apparatus according to the present embodiment may 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 baseband signal 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. The detected reception level is compared with the carrier sense level (threshold), and if the reception level is equal to or higher than the carrier sense level, the PHY processing unit 50 indicates that the medium (CCA: Clear Channel Assessment) is busy. Are output to the MAC processing unit 10 (more precisely, 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 precisely, the reception processing unit 40). .

  The PHY processing unit 50 performs a decoding process (including demodulation and decoding of an error correction code) on the received signal, a process of removing a physical header including a preamble (PHY header), and the like to extract a payload. According to the IEEE 802.11 standard, this payload is called 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 an MPDU (medium access control (MAC) protocol data unit). In addition, the PHY processing unit 50 notifies the reception processing unit 40 when reception of the reception signal is started, and notifies the reception processing unit 40 when reception of the reception signal is completed. In addition, when the received signal can be normally decoded as a physical packet (PHY packet) (if no error is detected), the PHY processing unit 50 notifies the reception end of the received signal and the medium is idle. Is sent to the reception processing unit 40. When an error is detected in the received signal, the PHY processing unit 50 notifies the reception processing unit 40 that an error has been detected with an appropriate error code corresponding to the error type. When the PHY processing unit 50 determines that the medium has become idle, the PHY processing unit 50 notifies the reception processing unit 40 of a signal indicating that the medium is idle.

  The MAC common processing unit 20 mediates transmission of transmission data from the upper processing unit 90 to the transmission processing unit 30 and transmission of received data from the reception processing unit 40 to the upper processing unit 90, respectively. In the IEEE 802.11 standard, data in the MAC data frame is called MSDU (medium access control (MAC) service data unit). The MAC common processing unit 20 once receives an instruction from the MAC / PHY management unit 60, converts the instruction into a suitable one for the transmission processing unit 30 and the reception processing unit 40, and outputs them.

  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 to the processing unit 50 corresponds to a physical layer management service access (PLME SAP) in an IEEE 802.11 wireless LAN (Local Area Network).

  In FIG. 1, the MAC / PHY management unit 60 is depicted as if the function unit for MAC management and the function unit for PHY management are integrated, but may be implemented separately. Good.

  The MAC / PHY management unit 60 holds a management information base (MIB). The MIB holds various information such as whether the capability and various functions of the terminal itself are valid or invalid. For example, whether or not the terminal itself is UL-OFDMA compliant, and information on the on / off of the function of the ability to implement UL-OFDMA when UL-OFDMA compliant may be retained. The memory for holding and managing the MIB may be included in the MAC / PHY management unit 60, or may be provided separately 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 other memory and rewrites rewritable parameters in the memory. It can be performed. The memory may be a volatile memory such as SRAM or DRAM, or a nonvolatile memory such as NAND or MRAM. Further, not a memory but a storage device such as an SSD or a hard disk may be used. In the base station, these pieces of information of other terminals as non-base stations can also be acquired by notification from the terminals. In that case, the MAC / PHY management unit 60 can refer to and rewrite information on other terminals. Or you may make it hold | maintain and manage the memory for memorize | storing the information regarding these other terminals separately from MIB. In that case, the MAC / PHY management unit 60 or the MAC common processing unit 20 can refer to / rewrite the other memory. In addition, when implementing UL-OFDMA, the MAC / PHY management unit 60 of the base station assigns terminals to which resource units for UL-OFDMA are allocated at the same time based on various information related to terminals as non-base stations or requests from the terminals. A selection function for selecting (that is, selecting a terminal that is a target of the current UL-OFDMA) may be provided. Further, the MAC / PHY management unit 60 or the MAC processing unit 10 may manage the transmission rate applied to the MAC frame to be transmitted and the physical header. The MAC / PHY management unit 60 of the base station may define and manage a support rate set that is a rate set supported by the base station. The support rate set may include a rate that a terminal connected to the base station must support and an optional rate.

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

  The management frame is used for management of communication links with other terminals. An example of the management frame is a beacon frame that broadcasts group attributes and synchronization information to form a wireless communication group that is a Basic Service Set (BSS) in the IEEE 802.11 standard. There are also frames exchanged for authentication or for establishing a communication link. Here, a state in which a certain terminal has exchanged information necessary for performing wireless communication with another terminal is expressed as an established communication link. Necessary information exchange includes, for example, notification of functions supported by the own terminal (for example, correspondence to the UL-OFDMA system and various capabilities described later), negotiation on setting of the system, and the like. The management frame is generated based on an instruction received by the transmission processing unit 30 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 includes notification means for notifying other terminals of various information via the management frame. The notification means of the terminal as a non-base station transmits the information indicating whether the terminal is compatible with a UL-OFDMA compatible terminal, an IEEE 802.11n compatible terminal, or an IEEE 802.11ac compatible terminal in a management frame. The station may be notified of the type of its own terminal. As this management frame, for example, there is an Association Request frame used in an association process, which is one of procedures for a 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 non-base station terminal of the availability of support for UL-OFDMA communication via a management frame. Examples of the management frame used for this include a Beacon frame and a Probe Response frame that is a response to a Probe Request frame transmitted by a non-base station terminal. The base station may have a function of grouping terminal groups connected to its own device. The above 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. An example of this management frame is a Group ID Management frame. The group ID may be an extended group ID (6 bits) defined for DL-MU-MIMO in IEEE Std 802.11ac-2013, for example, to include the case of UL-OFDMA. May be a group ID defined by another method. In addition, when the base station performs UL-OFDMA by designating the group, if there is information necessary for determining a resource unit used by a terminal belonging to the group, the base station can pass through any management frame. You may notify (when specifying a group so that it may mention later, a terminal is provided with the function to select a resource unit based on the method similar to a random backoff method).

  Here, the association ID (AID) will be described. AID is an identifier (terminal identifier) of a terminal assigned from the base station in an association process for allowing the terminal to connect to the base station and exchange data frames with the BSS under the base station. Specifically, in the association process, an association request frame is transmitted from the terminal to the base station, an association response frame is transmitted from the base station to the terminal, and the terminal status code field in the association response frame is “0”, that is, success. Is a successful process. Both the Association Request frame and the Association Response frame contain the communication capability (capability) of the transmitting terminal, so that both sides receive 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 frame and used as the AID of the transmission destination terminal. That is, at this time, an AID is assigned to the terminal from the base station, and the AID becomes valid for the terminal. In a state where the base station is connected to the terminal (Association), the AID of the terminal is valid. On the other hand, when a Dissociation frame is transmitted from the base station to the terminal and the terminal receives it, or when a Dissociation frame is transmitted from the terminal to the base station, the AID of the terminal becomes null. Of course, the AID is invalid for a terminal that has not undergone the association process with any base station. It can be said that the state where the AID is invalid is a state where the AID is not specified.

  The reception processing unit 40 includes a reception unit that receives various types of information from other terminals via a management frame. As an example, the receiving unit of the base station may receive information on availability of support for UL-OFDMA communication from a terminal as a non-base station. Further, information on a channel width (maximum usable channel width) that can be handled when the terminal is a legacy terminal (such as a terminal that supports the IEEE 802.11a / b / g / n / ac standard) may be received. The receiving means of the terminal may receive information on 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 base stations) via the management frame. For example, a UL-OFDMA-capable terminal may use a resource unit, a channel, or both of which it wishes to use in UL-OFDMA transmission, a carrier-sensing non-interfering channel, or a non-interfering resource unit, Or you may select from both of these. 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 assignment for UL-OFDMA communication for each UL-OFDMA compatible terminal based on the information. Note that the channels used in the 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 in a state where a communication link is established with the other terminal. For example, data is generated in the terminal by a user's application operation, and the data is carried by a data frame. Specifically, the generated data is passed from the upper 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, A data frame is generated by adding a MAC header. 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 physical packet is received by the PHY processing unit 50, the physical layer is processed based on the physical header to extract a MAC frame (in this case, a data frame), and the data frame is passed to the reception processing unit 40. When receiving the data frame (when it is determined 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 the extracted data is passed through the MAC common processing unit 20. To the host processor 90. As a result, application operations such as data writing and reproduction occur.

  The control frame is used for control when a management frame and a data frame are transmitted / received (exchanged) with another wireless communication apparatus. As the control frame, for example, before starting the exchange of the management frame and the data frame, an RTS (Request to Send) frame exchanged with another wireless communication device to reserve a wireless medium, a CTS (Clear to Send) frame. 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 CTS frame represents a delivery confirmation response. The CF-End frame is also one of the control frames. The CF-End frame is a frame for announcing the end of CFP (Contents Free Period) or the termination of a TXOP described later, that is, a frame permitting access to the 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 whether the response frame (control frame) needs to be transmitted and generates a frame. Necessary information (control frame type, information set in an RA (Receiver Address) field, etc.) is output to the transmission processing unit 30 together with a transmission instruction. The transmission processing unit 30 generates an appropriate control frame based on information necessary for generating the frame and a transmission instruction.

  When the MAC processing unit 10 transmits a MAC frame based on CSMA / CA (Carrier Sense Multiple Access with Carrier Avidance), it is necessary to acquire an access right (transmission right) on the wireless medium. The transmission processing unit 30 measures 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 instruct the modulation scheme and the encoding scheme used for transmission together. In addition to these, the transmission processing unit 30 may instruct transmission power. After obtaining the access right (transmission right), the MAC processing unit 10 is able to occupy the medium (Transmission Opportunity; TXOP). MAC frames can be exchanged continuously with the device. In TXOP, for example, a wireless communication device transmits a predetermined frame (for example, an RTS frame) based on CSMA / CA (Carrier Sense Multiple Access Carrier Avoidance), and a response frame (for example, a CTS frame) is correctly transmitted from another wireless communication device. Earned 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 (SIFS). In addition, as a method of acquiring a TXOP without using an RTS frame, for example, a data frame that requests transmission of an acknowledgment frame by direct unicast (a frame having a shape in which frames are concatenated or a payload is concatenated as described later). A management frame may be transmitted, and an acknowledgment frame (ACK frame or BlockACK frame) may be received correctly. Alternatively, when a frame that does not request transmission of a delivery confirmation response frame from another wireless communication device and has a duration longer than the time required for transmission of the frame in the Duration / ID field of the frame is transmitted The TXOP for the period described in the Duration / ID field may be interpreted from the stage at which the frame is transmitted.

  The reception processing unit 40 manages the carrier sense information described above. This carrier sense information is based on the physical carrier sense information related to busy / idle of the medium (CCA) input from the PHY processing unit 50 and the medium reservation time described in the received frame. Both virtual carrier sense (Virtual Carrier Sense) information is included. If any one of the 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 a NAV (Network Allocation Vector). It can be said that the medium reservation time represents the length of a period for instructing 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 be configured to concatenate 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 the PSDU. Further, not only data frames but also management frames and control frames are connected as MAC frames. In the case of A-MSDU, a plurality of data payloads MSDU are concatenated in the frame body of one MPDU. In both A-MPDU and A-MSDU, delimiter information (length information, etc.) is stored in the frame so that the concatenation of a plurality of MPDUs and the concatenation of a plurality of MSDUs can be appropriately separated at the receiving terminal. 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. In this case as well, delimiter information is stored in the frame. In addition, when A-MPDU or the like is received, responses to a plurality of connected MAC frames are collectively transmitted. In this case, a BA (BlockACK) frame is used instead of an ACK frame. In the following description and figures, the MPDU notation may be used, but this also includes the case of the above-described A-MPDU or A-MSDU.

  According to the IEEE802.11 standard, a non-base station terminal joins a BSS (this is called an infrastructure BSS) formed mainly by a base station, and data frames can be exchanged within the BSS. A plurality of procedures are defined in stages. For example, there is a procedure called association, and an association request (Association Request) frame is transmitted from a terminal of a non-base station to a base station to which the terminal requests connection. The base station transmits an ACK frame for the association request frame, and then transmits an association response frame that is a response to the association request frame.

  The terminal stores the capability of its own terminal in the association request frame, and can notify the base station of the capability of its own terminal by transmitting it. For example, the terminal may transmit the association request frame with information for specifying a channel and / or resource unit that can be supported by the terminal, and a standard that the terminal supports. You may make it set this information also to the flame | frame transmitted in the procedure of the reassociation (reassociation) for reconnecting to another base station. In this reassociation procedure, a terminal transmits a reassociation request (Reassociation Request) frame to another base station that requests reconnection. The other base station transmits an ACK frame for the re-association request frame, and then transmits a re-association response frame that is a response to the re-association request frame.

  In addition to the association request frame and the reassociation request frame, a beacon frame, a probe response (Probe Response) frame, or the like may be used as the management frame. The beacon frame is basically transmitted by the base station, and can store a parameter indicating the BSS attribute and a parameter notifying the base station itself. Therefore, the base station may add information indicating whether or not the base station can support UL-OFDMA as a parameter for notifying the capability of the base station itself. Moreover, you may notify the information of the support rate (Supported Rate) of a base station as another parameter. The support rate may include a rate that is mandatory for terminals participating 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 reception of a probe request frame from a terminal that transmits a beacon frame. Since the probe response frame basically reports the same content as the beacon frame, the base station notifies the terminal that 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 such as, for example, enabling the function of the UL-OFDMA communication of the terminal itself.

  In addition, a terminal may notify information on a rate that can be executed by the terminal among the support rates of the base station as information to notify the base station of the capability of the terminal. However, with regard to an indispensable rate among the support rates, it is assumed that a terminal connected to the base station has an ability to execute the indispensable rate.

  Of the information handled above, if there is information that determines the content of other information by notifying some information, the notification can be omitted. For example, let us consider a case where a capability corresponding to a new standard or specification is defined, and if the capability is supported, it is a UL-OFDMA compatible terminal. In this case, the presence of capability corresponding to the standard or specification may be notified as the certain information, and the notification that the terminal is an OFDMA-compatible terminal may not be explicitly performed as the other information.

  FIG. 4 shows a wireless communication system according to the present embodiment. This system includes a base station (AP: Access Point) 100 and a plurality of terminals (STA: STATION) 1 to 8. The base station 100 and subordinate terminals 1 to 8 form a BSS (Basic Service Set) 1. This system is a wireless LAN system conforming to the IEEE 802.11 standard using CSMA / CA (Carrier Sense Multiple Access with Carrier Avidance). Note that legacy terminals (such as IEEE802.11a / b / g / n / ac standard compatible terminals) other than the terminal (UL-OFDMA terminal) according to the present embodiment may exist in the BSS1.

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

  All of these fields need not be present, and some fields may not be present. For example, the Address3 field may not exist. In addition, there may be cases where both or one of the QoS Control and HT Control fields does not exist. There may also be no frame body field. There may also be other fields not shown in FIG. For example, an Address4 field may further exist. Further, an RU / AID field to be described later may be present in the MAC header or the frame body field.

  The Address 1 field contains the recipient address (Receiver Address; RA), the Address 2 field contains the source address (Transmitter Address; TA), and the Address 3 field contains the BSS identifier according to the use of the frame. Either a certain BSSID (Basic Service Set IDentifier) (which may be a wildcard BSSID for which all BSSIDs are set by putting 1 in all bits), or TA. However, as will be described later, in the present embodiment, one of the features is that the Address 1 and Address 2 fields are used by a method different from that described here.

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

  The Duration / ID field describes the medium reservation time. 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. Is determined. Such a mechanism for virtually determining that a medium is busy, or a period during which a medium is virtually busy, is referred to as NAV (Network Allocation Vector) as described above. The QoS field is used for performing 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 includes an Element ID field, a Length field, and an information (Information) field. The information element is identified by an Element ID. The information field stores the content of information to be notified, and the Length field stores length information of the information field.

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

  FIG. 7 shows an example of an operation sequence between 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. 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 a CSMA / CA basis 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 using one channel having a basic channel width (for example, 20 MHz). As an example of single user communication, when data for uplink transmission is held in a terminal, an access right to a wireless medium is acquired according to CSMA / CA. For this reason, the terminal performs carrier sense during the carrier sense time (waiting time) between DIFS / AIFS [AC] and a randomly determined backoff time, and when the medium (CCA) is determined to be idle, for example, An access right to transmit one frame is acquired. The terminal transmits a data frame including data to be transmitted (more specifically, a physical packet including the data frame). When the base station normally receives the data frame, the terminal confirms delivery after SIFS time from completion of reception of the data frame. An ACK frame that is a response frame (more specifically, a physical packet including an ACK frame) is returned. By receiving the ACK frame, the terminal determines that the data frame has been successfully transmitted. The data frame to be 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). The DIFS / AIFS [AC] time means either one of DIFS and AIFS [AC]. When QoS is not supported, it indicates DIFS time. When QoS is supported, it indicates AIFS [AC] time determined according to an access category (AC) (to be described later) of data to be transmitted.

  The base station determines the start of UL-OFDMA at an arbitrary timing. In this example, it is assumed that UL-OFDMA transmission is performed on the same channel (single channel with a basic channel width of 20 MHz) as single user communication. 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 the trigger frame) 501. The trigger frame 501 is transmitted using a channel having the same basic channel width as that of the single user communication. As an example, the physical packet including the trigger frame is obtained by adding a physical header to the head of the trigger frame. For example, as shown in FIG. 8, the physical header includes L-STF (Legacy-Short Training Field), L-LTF (Legacy-Long Training Field), L-SIG (Legacy Signal) defined in the IEEE 802.11 standard. Field). L-STF, L-LTF, and L-SIG are fields that can be recognized by terminals of legacy standards such as IEEE802.11a, for example, signal detection, frequency correction (channel estimation), and transmission speed (transmission rate). Such information is stored. Fields other than those described here may be included (for example, a field in which a legacy standard terminal cannot be recognized and a UL-OFDMA compatible terminal can be recognized).

  The trigger frame 501 may be a frame that can be received and decoded by legacy terminals as well as UL-OFDMA compatible terminals. It is assumed that the access right is acquired in advance according to CSMA / CA before the base station transmits the trigger frame. Acquisition of the access right is the same as that of the terminal described above. There are a plurality of frame formats and usage methods (interpretation rules) of the trigger frame 501 in this embodiment, and the operation of the terminal when receiving the trigger frame 501 differs depending on any of them. In the description of this sequence, an example of typical operations will be described, and operations as variations will be described later. Here, as an example, the trigger frame 501 includes information for specifying a plurality of resource units that can be used in UL-OFDMA transmission and information for specifying a plurality of terminals that are candidates for UL-OFDMA transmission. . The information specifying the resource unit specifies, for example, all or part of a plurality of resource units defined in the channel. The information specifying the plurality of candidate terminals includes, for example, at least one group ID or an identifier (AID or MAC address) of each of the plurality of terminals. Examples other than those described here are possible.

  The trigger frame 501 transmitted from the base station is received by the terminals 1-8. The terminals 1 to 8 decode the trigger frame 501 and determine whether the own terminal belongs to the group with the group ID specified by the trigger frame 501. Note that the terminal is notified of the group ID of the group to which the terminal belongs from the base station at the time of the association process or at an arbitrary timing thereafter. Notification of correspondence between a terminal other than the terminal itself and the group may also be received. When the own terminal belongs to the group ID specified in the trigger frame and holds data for uplink transmission, the resource used by the own terminal from a plurality of resource units specified in the trigger frame 501 Units are selected based on a method similar to the random backoff method. A terminal that does not hold data for uplink transmission does not need to be selected, but can be configured to be selected. The number to be selected may be determined in advance, may be specified in the trigger frame 501, or may be grasped by other methods. 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 information for specifying resource units. The resource units 1 to n may be all resource units defined in a channel used in UL-OFDMA, or may be a part of resource units. The resource units 1 to n may be identified by, for example, RU # 1 to RU # n that are respective identifiers or numbers. A configuration is also conceivable 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 by the trigger frame 501. In this case, the terminal grasps available resource units from the identifier of the set.

  In this example, it is assumed that among the terminals 1 to 8, the group to which the terminals 1, 3, 4, and 6 belong is specified, and the group to which at least one of the terminals 2, 5, 7, and 8 belongs is not specified. As an example, 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 specified. Each of the terminals 1, 3, 4, and 6 holds data for uplink, and all these terminals acquire the resource unit selection right and are randomly assigned to the resource unit 2 from the resource units 1 to n. Assume that 4, 6, and 7 are selected. The terminals 1, 3, 4, and 6 receive data frames 511, 513, 514, and 516 including data for uplink transmission (more specifically, physical data including the data frame) after a predetermined time T 1 from completion of reception of the trigger frame 507. Packet) to the base station. The data frames 511, 513, 514, and 516 are transmitted using the resource units 2, 4, 6, and 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 by the IEEE 802.11 wireless LAN MAC protocol specification, or other predefined time. Time (IFS) can be used. The fixed time T1 may be determined by the system or specification, 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 is stored in a predetermined field of the trigger frame 501, and the terminals 1 to 4 may acquire 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, whereby UL-OFDMA transmission is performed. When a terminal performs an operation of selecting a resource unit even though there is no data to be transmitted in uplink, the terminal has a data field with a predetermined format frame, for example, a physical header and a MAC header. A Null Packet (null packet) that is a non-existing frame may be transmitted. Alternatively, the terminal may select a resource unit but not perform any transmission operation. When the base station receives a 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 from the terminals 1, 3, 4, and 6 by OFDMA. The base station receives data frames 511, 513, 514, and 516 in resource units 2, 4, 6, and 7, respectively. In other resource units, since no data frame is transmitted from any terminal, the base station does not receive the data frame.

  When the base station correctly receives the data frames transmitted from the terminals 1, 3, 4, and 6, it 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 in the IEEE 802.11 wireless LAN MAC protocol specifications, or other predefined time. Time (IFS) can be used.

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

  As yet another method, a single frame including all the acknowledgments for the 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 in the IEEE 802.11 standard may be used. As an example, the BA information field of the Multi-TID BA frame is arranged for the number of terminals, and the terminal identifier (for example, AID (Association ID) or a part of AID) is set in the reserved field in the TID information subfield of each BA information field. Set. As usual, values 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 to which a delivery confirmation response should be returned. The 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 belong in common. In this way, BA can be notified to a plurality of terminals in one frame. 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 terminals 1, 3, 4, and 6, the terminal identifier is set in a part of the reserved fields in the TID information subfield of each BA information field, and the remaining one is set. The bit of the part field is set (set to 1). When the bit is set, the Block Ack Starting Sequence Control subfield and the Block Ack Bitmap subfield are omitted (does not exist). Thereby, ACK of a some terminal can be notified with one flame | frame. As another example, a partial state operation is used, and a 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 used, or a new frame may be defined instead of using an existing frame.

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

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

  In the operation example described above, when the terminal specified by the group ID in the trigger frame has the right to select the resource unit, the resource unit is selected at random from the plurality of resource units specified in the trigger frame. As another operation, the base station can individually specify a resource unit for each terminal in the trigger frame, and the terminal specified in the trigger frame can also select the resource unit specified in the trigger frame. For example, the identifiers (AID and the like) of the terminals 1, 3, 4, and 6 are designated in the trigger frame, and the identifiers of the resource units 2, 4, 6, and 7 are individually designated for these terminals. As a result, the same sequence as in FIG. 7 is performed. Several resource units may be assigned to the same terminal in succession. An operation combining both of these operations (random selection of resource units and individual designation) is also possible. Also, a terminal that is not yet connected to the base station can be designated as a UL-OFDMA target by a trigger frame. 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. FIG. 9B shows an example in which the RU / AID field is not in the MAC header but in the frame body field. When the RU / AID field is provided in the frame body field, if the trigger frame 501 is a management frame, it is conceivable to provide the RU / AID field as an information element as shown in FIG. If it is a control frame or a data frame, the RU / AID field may be added to the frame body field in an identifiable format. In the following description, it is assumed that it does not matter whether the RU / AID field is in the MAC header or the frame body field unless it is particularly necessary to distinguish.

  FIG. 10 shows a configuration example of the RU / AID field of the trigger frame and an example of each field length. The field length shown here is merely an example, and other values may be used. For example, the field length is shown here in units of octets (8 bits), but 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 an RU field (RU_1 to RU_n) and an AID field (AID_1 to AID_n). As a basic method of using this frame format, a resource unit is specified and a terminal to which the resource unit is assigned is specified using an RU field and an AID field. The identifier of the resource unit is set in the RU field, and the identifier (AID in this case) of the terminal to which the resource unit is assigned is set in the AID field. Thereby, 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 as a new value, a field for notifying whether or not it is a trigger frame is separately provided in the MAC header, and a bit is set in the field to notify that it is a trigger frame. It doesn't matter. In the Duration / ID field, the length of the period for which the use of the wireless medium is to be occupied is specified from the end of the trigger frame. For example, the time length to the end of the delivery confirmation response frame is specified. Values may be set as usual in the Sequence Control and FCS fields. In the Address 1 field, a broadcast address or a multicast address may be set as RA. The MAC address (BSSID) of the base station may be set as TA in the Address2 field. Note that n (the number of sets of RU fields and AID fields) may be fixed or variable. In the case of variable, a field for determining n may be provided at the head 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 not included in the combination of the resource unit identifier and the AID.

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

(First example)
Also in this case, 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 identifiers of 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 as a new value, a field for notifying whether or not it is a trigger frame is separately provided in the MAC header, and a bit is set in the field to notify that it is a trigger frame. It doesn't matter. In the Duration / ID field, the length of the period for which the use of the wireless medium is to be occupied is specified from the end of the trigger frame. For example, the time length to the end of the delivery confirmation response frame is specified. Values may be set as usual in the Sequence Control and FCS fields.

  In the Address 1 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. Usually, since RA (unicast address, broadcast address or multicast address) is set in the Address 1 field, setting the group ID is an operation different from normal. Therefore, it is necessary to notify that the group ID is set in the Address1 field. Therefore, in the Address 2 field, a value obtained by converting the Individual / Group bit (bit at a specific position) of the MAC address (BSSID) of the base station to 1 is set. Usually, since TA is set in the Address2 field, setting the MAC address (BSSID) of the base station is a normal operation. Here, in order to notify that the group ID is set in the Address 1 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 eighth bit of the MAC address. And the Individual / Group bit of the MAC address of the terminal (including the base station) is 0. In the case of a broadcast address or a multicast address, it is 1. Therefore, by converting this Individual / Group bit from 0 to 1, the terminal is notified that the group ID is set in the Address 1 field (normally, since the transmission of the trigger frame is from the base station, TA used in the Address2 field is the MAC address of the base station, and the Individual / Group bit is 0). Therefore, since the Individual / Group bit in the Address 2 field is 1, the terminal can determine that the group ID is set in the Address 1 field, and the source address of the trigger frame is the Individual / Group bit in the bit string of the Address 2 field. It can also be determined that 1 is returned from 1 to 0. Therefore, as the RA when the terminal transmits a data frame, the RA in which the Individual / Group bit of the bit string of the Address2 field is returned from 1 to 0 (that is, the MAC address of the base station) can be used.

  Note that n (the number of sets of RU fields and AID fields) may be fixed or variable. In the case of variable, a field for determining n may be provided at the head 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 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 from the value of the type and subtype of the frame control field, for example. Since “Individual / Group” in the Address 2 field is 1, it is understood that the group ID is set in the Address 1 field, and the group ID set in the Address 1 field is read. It is determined whether the terminal belongs to the group indicated by the group ID. If the terminal does not belong, the trigger frame is discarded and the process is terminated. When the own terminal belongs to the group indicated by the group ID, the RU / AID field is confirmed, and the resource unit indicated by the identifier set in the n RU fields is recognized as a resource unit that is a use candidate. . Ignore n AID fields. For example, the terminal subtracts the number of resource units that are candidates for use from a backoff counter value that is randomly selected in advance. 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. Any method can be selected at random. For example, a resource unit having a number obtained by adding 1 to the remainder when a random number value is divided by n may be specified by using a random number generator that generates a certain number of digits. In this case, resource unit 1 is selected if the remainder value is zero, and resource unit n is selected if the remainder value is n-1. The example described here is only an example, and other methods may of course be used. The terminal transmits a data frame as described above using a randomly selected resource unit. Note that RA (value of the Address 1 field) of the data frame is the MAC address (BSSID) of the base station, and TA (value of the Address 2 field) is the MAC address of the own terminal.

  According to the first example described above, since only the terminals belonging to the group specified by the group ID are candidate terminals for UL-OFDMA, it is more random than when all the terminals that have received the trigger frame are candidate terminals. The possibility that resource units to be selected overlap between terminals can be reduced. When the same resource unit is selected among a plurality of terminals, signal interference occurs in the resource unit at the base station, and frames from the 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. Differences from the first example will be described below. An unused value as an AID or an AID assigned to a terminal is set in the n AID fields. “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 expresses AID using 14 bits of 2 octets (16 bits), if the range of AID values that can be assigned by the base station is 1 or more and 2007 or less, 2 in the AID field Of 14 octets (16 bits), 14 bits (0th to 13th bits) are all set to 0 or a value within 2008-16383. The 14th and 15th bits set a fixed value (for example, “11”). The example of setting an unused value of AID described here is similar to the method 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 selects a resource unit at random, an unused value is set as the AID in the corresponding AID field. On the other hand, when a resource unit to be used by a terminal is designated, the AID assigned to the terminal is set in the corresponding AID field. When an unused value is set as an AID in all n AID fields, all the values set in these n fields may or may not be common values.

  The terminal determines whether the value of the AID field is “an unused value as an AID”, and “an unused value as an 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 it is a value that can be used as an AID (in the above example, the 0th to 13th bits are bits representing the value in 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 the resource unit. If the number of resource units required for communication is plural (H) and the specified number of resource units is less than H, only the difference resource unit can be selected from available resource units at random. Good.

  According to the second example described above, UL-OFDMA candidate terminals can be limited to a specific group, and resource units to be used for each terminal can be designated. Accordingly, for example, when a terminal uses a plurality of resource units, a part of resource units can be designated by the base station, and the remaining resource units can be selected at random. Since the resource unit specified by the base station is not used by other terminals, interference between terminals in the resource unit at the base station does not occur, and more reliable communication can be expected.

(Third example)
In the second example, an unused value as an AID or an AID assigned to a terminal is set in the AID field. In this example, an unassigned value or an AID assigned to a terminal is set as the AID. Differences from the second example will be described. A value not assigned as an AID is an AID value in a range that the base station can assign as an AID in addition to an unused value as an AID, but includes an AID that has not been assigned yet. When the base station notifies each terminal of a list of terminals and AIDs, the same operation as in the second example is possible with this method. That is, the base station sets an unassigned value as an AID in the corresponding AID field when causing the terminal to select a resource unit at random. On the other hand, when a resource unit to be used by a terminal is designated, the AID assigned to the terminal is set in the corresponding AID field. The terminal determines whether the value of the AID field is “unassigned value as AID” by using the above list, and if it is “unassigned value as AID”, the corresponding resource unit can be used. It is judged that. If the value is already assigned as the AID, it is determined whether the value is the AID of the own terminal. If the value is the AID of the own terminal, the base station determines that the use of the corresponding resource unit is specified 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 the resource unit. If the number of resource units required for communication is plural (H) and the specified number of resource units is less than H, only the difference resource unit can be selected from available resource units at random. Good.

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

(Fourth example)
In the fourth example, the base station sets, in the AID field, an AID of a terminal that prohibits use of the resource block among terminals belonging to the group of 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 use of a specific terminal, but use of any of the remaining terminals is permitted, the AID of the terminal whose use is prohibited is set in the AID field. When any use of all terminals belonging to the group with the group ID is permitted, an unused value is set as the AID. Instead of an unused value as an AID, an unassigned value as an AID may be used as in the third example. For a resource unit whose AID is set in the AID field, the terminal determines that the terminal cannot use the resource unit. It is determined that a resource unit in which an unused value as AID (or an unassigned value as AID) is set can be used. The terminal randomly selects a resource unit to be used by the terminal from available resource units.

  According to the above-described fourth example, it is possible to allow a certain resource unit to be randomly selected for another terminal while prohibiting the use to a specific terminal.

(Fifth example)
In the fifth example, the method of notifying that the group ID is set in the Address 1 field of the trigger frame is different from the first to fourth examples.

  The reason that it is necessary to notify that the group ID is set in the Address 1 field is that the unicast address, broadcast address, or multicast address is normally set in the Address 1 field, and the group ID is set. Is not expected. Therefore, it is necessary to be able to distinguish whether a group ID is set in the Address 1 field or whether an address such as broadcast or multicast is set.

  In the first to fourth examples, the Individual / Group bit in the Address2 field is converted to 1 in order to notify that the group ID is set. However, in this example, the Individual / Group bit is maintained at 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 is set is notified to the terminal using another field. For example, the presence / absence of a group ID is set using a reserved area in the frame control field. Alternatively, the QoS field shown in FIG. 5 is also left in the trigger frame, and the presence / absence of a group ID is set in the reserved area in the QoS field. Alternatively, a new field, 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. Except for notifying the presence / absence of a group ID, this is the same as the first to fourth examples.

(Sixth example)
In the sixth example, the method of notifying that the group ID is set in the Address 1 field of the trigger frame is different from the first to fifth examples. 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 a reserved area of an existing field is used. In contrast, 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 only in a specific one or more AID fields, for example, the first AID field. In the sixth example, “unused value as AID” is set in the AID field means that a group ID is set in the Address 1 field. Instead of “unused value as AID”, “unassigned value as AID” may be used.

  When the terminal receives the trigger frame (recognizes that the received frame is a trigger frame according to the type and subtype of the frame control field), 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 values are “unused values as AIDs” (or “unassigned values as AIDs”), it is understood that a group ID is set in the Address1 field. Alternatively, the values of all AID fields in the RU / AID field are confirmed, 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 Address 1 field, the terminal reads the value set in the Address 1 field and determines whether the terminal belongs to the group of 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 a resource unit that can be used by the own terminal. A resource unit to be used by the terminal is randomly selected from the resource units specified as described above. The subsequent operations are the same as in the first example.

(Seventh example)
In the seventh example, the trigger frame format shown in FIG. 12 is used. A difference from the format example shown in FIG. 9 is that the RU / AID field is replaced with an 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 in the system or specification. The setting method of each AID field and other fields is the same as the example described so far. In addition, the terminal and the operation when receiving the trigger frame are the same as the previous examples except that the operation for confirming the RU field is unnecessary.

(Eighth example)
In the eighth example, the trigger frame format shown in FIG. 13 is used. A 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. As in the first to sixth examples, resource unit identifiers that can be used in UL-OFDMA are set in each RU field. The other field setting methods are the same as those in the first example or the fifth example.

  For example, when setting is performed according to the first example, a group ID is set in the Address 1 field, and an Individual / Group bit of the MAC address of the base station is set from 0 to 1 in the Address 2 field. The type of the frame control field is “control” or “management”, and the newly defined value for the trigger frame is used as the subtype. Alternatively, the type may be “data”. In this case, instead of defining the subtype as a new value, a field for notifying whether or not it is a trigger frame is separately provided in the MAC header, and a bit is set in the field to notify that it is a trigger frame. It doesn't matter.

  When setting is performed according to the fifth example, the group ID is set in the Address 1 field, and the MAC address (BSSID) of the base station is set in Address 2. In addition, the presence / 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, an HE (High Efficiency) control field shown in FIG. 11 is provided in the MAC header, and the presence / 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.

  When the terminal receives a trigger frame (for example, when it recognizes that the received frame is a trigger frame according to the type and subtype of the frame control field), it knows the available resource units from each RU field in the RU notification field. Then, a resource unit is selected at random from the grasped resource units. Subsequent operations are the same as those in the first example.

(Ninth example)
In the ninth example, the trigger frame format shown in FIG. 9 is used as in the first to sixth examples, but the usage method of the Address 1 field and the AID field is different. In this example, a broadcast address or a multicast address is set in the Address 1 field. The frame in which the broadcast address is set is a frame that is received by any of the terminals 1 to 8 as addressed to its own terminal. When a multicast address is set, it is assumed here that the terminals 1 to 8 are targets of the multicast address, and the frame is received as addressed to the own terminal. 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 by replacing the Individual / Group bit of the MAC address of the base station from 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 there is. In each AID field, a group ID of a group to be subjected to UL-OFDMA is set as a common value. FIG. 14 shows how a group ID is set in each AID field. In the example of FIG. 14, the length of the group ID is originally set to 2 octets for the purpose of the AID field for setting the AID. For example, in the case of bits, the AID field length may be changed, such as a 1-octet field. 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, a newly added field, or the like.

  When the terminal receives the trigger frame, the terminal determines that it is a frame to be received by the terminal from the address of the Address 1 field of the received frame, and recognizes that it is a trigger frame based on the type and subtype of the frame control field. Since the Individual / Group bit of the Address2 field is 1, it is understood that the group ID of 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 own terminal. When the group of the own terminal is not indicated, the own terminal determines that it is not a subject of the current UL-OFDMA and discards the frame. On the other hand, when the group ID indicates the group ID of the own terminal, the identifier of the resource unit is read from each RU field, and the available resource unit is grasped. Then, a resource unit is randomly selected from the grasped available resource units. Subsequent operations are the same as those in the first example.

(Tenth example)
Hereinafter, the difference from the ninth example will be described. In the ninth example described above, a common group ID is set in each AID field, but in the tenth example, it is allowed to set a different group ID for each AID field. The base station determines a group that can be used 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 the terminal belongs to the group ID. The terminal recognizes only the resource units specified in the RU field corresponding to the AID field in which the group ID to which the terminal belongs is set as a resource unit that can be used by the terminal. Then, a resource unit is randomly selected from the grasped available resource units. Subsequent operations are the same as those in the first example.

(Eleventh example)
In the ninth example and the tenth example described above, the Individual / Group bit of the MAC address of the base station is replaced from 0 to 1 in the Address2 field to notify that the group ID is set in each AID field. Set things. On the other hand, in the eleventh example, it is notified that the group ID is set in each AID field 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 an HE control field shown in FIG. Information (group ON information) is notified. Or, if there is an unused area (reserved area) in the RU field (for example, if all the resource units can be identified by the upper 6 bits, the last 2 bits area), set the group ON information 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 specifying a terminal for each resource unit is performed). In this case, the base station sets information (group OFF information) for notifying that the AID is set instead of the group ON information in the above-described area or new field. In the Address2 field, the base station MAC address (BSSID) is set as usual. In the Address1 field, a broadcast or multicast address is set as in the ninth and tenth examples.

  The terminal that has received the trigger frame determines whether the group ON information is set in the reserved area of the existing field or the newly defined field. If the group ON information is set, the terminal enters the AID field. Know that a group ID (not AID) is set. Subsequent operations are the same as those in 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 Address 1 field, as in the ninth and tenth examples, and the MAC address (BSSID) of the base station is set in the Address 2 field as usual. Set.

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

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

(13th example)
In the first to twelfth examples, there are two types of frame usage patterns when the group ID is set and when the group ID is not set. When setting the group ID, set the Individual / Group bit in the Address2 field to 1, set the group ID in the reserved area of the existing field, a newly defined field, or a predetermined area of the AID field. Setting information (group ON information). In contrast, in the thirteenth example, a group ID field is defined by default in the frame format. An example of the frame format in this case is shown in FIG. A group ID field is 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. As in the first example, an arbitrary value may be set in the AID field (when the terminal does not need to read the AID field).

  Alternatively, when a specific resource unit is specified for a specific terminal among the terminals belonging to the group specified by the group ID field, the specific ID is displayed in the AID field corresponding to the RU field for specifying the specific resource unit. You may set AID of a terminal. An unused value as an AID or an unassigned value as an AID may be set in the AID field corresponding to the RU field that specifies a 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 (the same applies to the other examples described so far). 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 by 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 be changed from 3 × n to 2 × n.

  Note that a broadcast or multicast address may be set in the Address 1 field, and a MAC address (BSSID) of the base station may be set in the Address 2 field as usual. The setting of the frame control field is the same as in the first to twelfth examples.

  The terminal that has received the trigger frame determines whether the terminal belongs to the group specified in the group ID field. If the terminal belongs to the group, the terminal determines from the value set in each RU field set in the RU / AID field. Know the available resource units. Then, a resource unit is randomly selected from the grasped resource units based on the above-described operation. Subsequent operations are the same as other operation examples. If the terminal determines that the terminal does not belong to the group specified in the group ID field, the terminal enters the sleep mode (power saving mode) for an arbitrary time such as the period specified in the Duration / ID field. You may make a transition. The operation for transitioning to the sleep mode is similarly applicable to the first to thirteenth examples.

  Alternatively, if the own terminal belongs to the group specified in the group ID field, the AID (or partial AID) set in the AID field is checked to determine whether the own terminal is specified. When the own terminal is designated, it is determined that the own terminal uses the resource unit set in the corresponding RU field. If the number of resource units specified for the terminal is less than H (an integer greater than or equal to 1), which is the number of resource units necessary for communication, an unused value as an AID or an unassigned value as an AID The RU field corresponding to the AID field in which is set is specified, and the resource unit specified in the RU field is grasped as an available resource unit. Then, resource units that are less than H from the grasped available resource units may be additionally selected at random.

(14th 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 an RU notification field. The configuration of the RU notification field is the same as that in 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 in the case of ignoring the AID field in the thirteenth example can be realized with a shorter trigger frame length.

(15th 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 there is no RU notification field. When this format is used, it is assumed that resource units that can be used in UL-OFDMA are determined in advance and are notified from the base station to each terminal in advance or determined in advance by the system or specifications. As a result, a mechanism for performing UL-OFDMA by causing each terminal to designate a resource unit at random can be realized with a trigger frame having a shorter frame length.

(Sixteenth example)
In the description so far, a terminal that is already connected to a base station and is assigned an AID is targeted for UL-OFDMA, but a terminal that is not connected to a base station and has not been assigned an AID is It is also possible to specify the target of UL-OFDMA in the trigger frame. In this case, a certain group ID is defined for a terminal for which no AID is specified. Therefore, a terminal connected to the base station does not belong to this group ID. The base station generates and transmits the trigger frame in which the group ID is set based on any of the first to fifteenth examples described so far. The terminal that has not received the trigger frame and has not been assigned an AID (terminal not connected to the base station) determines that the terminal belongs to this group ID. The terminal may be notified of the group ID in advance by a beacon frame or the like from the base station, or the group ID may be determined by the system or specifications. The corresponding terminal randomly selects a resource unit as described above. The sizes of the resource units that can be used at this time may be equal to each other. The terminal can uplink-transmit an association request frame with the selected resource unit (in this case, the base station accepts association request frames from a plurality of terminals simultaneously). The association request frame is an example, and other frames such as a reassociation request frame and a probe request frame may be used.

  In order to realize the same operation, an unused value as an AID may be set in the AID field of any of the formats described so far, instead of using a group ID for terminals not designated by AID. . In this case, an unused value as an AID means that, unlike the first to fifteenth examples so far, a terminal not designated by AID (a terminal not connected to a base station) is designated. A terminal not designated by AID recognizes the AID range (for example, 1 to 2007) in advance by the system or specifications, and determines that a value outside this range is unused as an AID. A terminal that has not received an AID (a terminal that is not connected to a base station) that has received a trigger frame has its own terminal specified if an unused value is set as an AID in any AID field. to decide. Then, the terminal can randomly select a resource unit, and uplink transmission of a frame such as an association request frame can be performed using the selected resource unit.

  Note that UL-OFDMA in which a terminal having no AID specified and a terminal having an AID specified described in the first to fifteenth examples is also possible. In this case, the sixteenth example can be easily realized by combining any one or more of the first to fifteenth examples.

(17th example)
A group ID may be provided for a terminal that is performing power saving, and this may be designated by a trigger frame. For example, it is assumed that there is a case where a terminal performing power saving is required to periodically send a specific frame to the base station. For example, it is conceivable that PS-Poll is requested periodically. Therefore, the base station may receive a specific frame from a plurality of terminals by transmitting a trigger frame designating the group ID of the group of terminals performing power saving in accordance with the timing. Since individual terminals do not require processes such as carrier sense and access right acquisition by backoff, compared to the case of normal single-user transmission, it is possible to further reduce power consumption.

(18th example)
The frame formats shown in FIGS. 9 to 17 described above are examples, and other fields may exist in the trigger frame. For example, there may be a field for setting information specifying the packet length (PPDU length) of a physical packet transmitted by UL-OFDMA. You may set the information which designates MCS (modulation coding system) used in UL-OFDMA, or a transmission rate. The packet length and / or MCS 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 specified for each resource unit. The field for setting the information described here may be an arbitrary position in the trigger frame. For example, it may exist in the HE Control field as shown in FIG. 11, may exist in the frame body field, or may exist in the RU / AID field. The example described here is an example, and there may be other fields for setting various information.

(Combination between 1st to 18th examples)
The first to eighteenth examples described above can be realized independently, and two or more may be arbitrarily combined as long as there is no contradiction in operation. For example, combining the thirteenth example and the fourth example, in the thirteenth example, an AID of a terminal that prohibits the use of a resource block may be set in the AID field. Of course, other combinations are possible.

  FIG. 18 shows a flowchart of an example of the operation of the base station according to the embodiment of the present invention. When the base station determines the start of UL-OFDMA at an arbitrary timing, the base station determines whether the UL-OFDMA target terminal specification method is an individual specification method for individually specifying individual terminals or a group specification method for specifying a group. Determine (S101). Note that the determination of the method may be performed before the start of UL-OFDMA, or may be determined in advance as one of them.

  When the individual designation method is determined (NO in S102), individual terminals that perform UL-OFDMA at this time are selected from the OFDMA-compatible terminals that are connected to the base station, and the resource unit to be allocated to each terminal is determined ( S103). The method for selecting individual terminals may be any method. For example, UL-OFDMA request presence / absence may be collected from each terminal in advance and selected from the requested terminals. Alternatively, based on the amount of data to be transmitted at each terminal, the terminal having the largest data amount may be preferentially selected, or the terminal having the same data amount may be selected. In addition, a terminal may be selected from terminals belonging to the same group. At this time, as criteria for selecting a group, items such as the presence / absence of a request for UL-OFDMA transmission for each terminal belonging to each group and the amount of data for transmission may be considered. Alternatively, the terminal or group may be selected by round robin, or the terminal or group may be selected at random. Alternatively, a terminal having data that is estimated to be the same or close to the size of data to be transmitted next is selected, or a terminal having the same data generation period or a similar generation period (a terminal whose generation period is included within a certain value) It is also possible to select a predetermined number of terminals or the like 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 having a small spatial correlation (small interference) may be selected based on the channel response. Note that the number of terminals to be selected is equal to or less than the maximum number of available resource units. However, when the above-described OFDMA & MIMO scheme is used, the number of terminals greater than the maximum number of resource units is also possible. When the lower limit of the number of terminals to be selected is determined, the number of terminals equal to or higher 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.

  Further, the resource unit allocation method may be arbitrary. For example, when all resource units have the same bandwidth and one resource unit is allocated to each terminal, an arbitrary one may be allocated to each terminal. Further, when there are a plurality of bandwidth resource units, a resource unit with a larger bandwidth may be allocated to a terminal having a larger amount of data for transmission. Further, when assigning a plurality of resource units to one terminal, it is possible to select resource units arranged continuously in the frequency domain, or to select resource units arranged discontinuously. .

  In addition, the band used for UL-OFDMA uplink transmission may be determined in advance by the system or specification, or may be determined when UL-OFDMA is performed in the base station. 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 the predetermined field of the trigger frame (S104). The predetermined field depends on the format to be used, and in the case of the format of FIG. 10, the RU field and the AID field in the RU / AID field. In the Address 1 field, a broadcast address or a multicast address is set as RA. Also, 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. Note that the identifier of the resource unit may be a unique value among a plurality of bands such as 20 MHz, 40 MHz, and 80 MHz, or the same value identifier may be allowed to be used in different bands. When it is allowed to use identifiers of the same value in different bands, information identifying the band to be used is notified in the trigger frame (for example, the HE Control field in FIG. 11) in addition to the resource unit identifier, or used in advance. It is only necessary 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 using a channel having a basic channel width (for example, 20 MHz) that can be transmitted and received by legacy terminals, for example. Note that the band used for UL-OFDMA uplink transmission is the band that transmitted the trigger frame. When the uplink transmission band is 20 MHz, this is the same as the band that transmitted the trigger frame. When the uplink transmission band is 40 MHz, the trigger frame may be transmitted through two 20 MHz wide channels within the 40 MHz. When the uplink transmission band is 80 MHz, the trigger frame may be transmitted using 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 the connected OFDMA-compatible terminals (S106). . Any method may be used to select the group. For example, the presence / absence of UL-OFDMA requests from each terminal may be collected in advance, and a group including the requested terminals may be selected. Alternatively, a group including a terminal having the largest data amount may be selected based on a transmission data amount in each terminal, or a group having the largest number of terminals having the same data amount may be selected. Alternatively, a group may be selected by round robin or a group may be selected at random. Or, select the group that has the most terminals with data that is estimated to be the same or near the size of the data to be transmitted next, or terminals that have the same or similar data generation cycle (the generation cycle is constant). It is also possible to select a group having the largest number of terminals included within the value, or a predetermined number of terminals having the closest occurrence cycle. Note that one group is assumed here, but it is also possible to select a plurality of groups 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.

  In addition, the band used for UL-OFDMA uplink transmission may be determined in advance by the system or specification, or may be determined when UL-OFDMA is performed in the base station. 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 of FIG. Also, in the Address2 field, a value obtained by inverting the Individual / Group bit of the MAC address (BSSID) of the own station from 0 to 1 is set. A value for a trigger frame may be set in the type field and subtype field of the frame control field. A method other than those described here may be used, or a format other than that shown in FIG. 10 may be used. Since details have been described above, further description is omitted. In addition, the base station may set information for identifying the band to be used in the trigger frame (for example, the HE Control field in FIG. 11), may notify in advance, 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) receiving the trigger frame. For example, when using a channel with a basic width of 20 MHz for uplink transmission, as shown in FIG. 19, the trigger frame is transmitted with the channel, and when using a channel with a width of 40 MHz, it is included in the 40 MHz. The trigger frame is transmitted on each of the two 20 MHz wide channels, and when the 80 MHz wide channel is used, the trigger frame is transmitted on each of the four 20 MHz wide channels included in the 80 MHz. The receiving terminal determines that uplink transmission is possible on the channel (band) that received the trigger frame. On the terminal side, if the trigger frame was successfully received on some channels but failed to be received on another channel, the resource unit included only in the channel (band) that was successfully received was selected. You may make it restrict | limit the resource unit to perform.

  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 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 in FIG. 18, in addition to selecting a group, terminal selection and resource unit assignment may be performed. In this case, a group ID is set in the trigger frame, and a set of an identifier (AID or the like) of the selected terminal and an identifier of the resource unit is set, so that the resource unit is designated for the selected terminal. Also good. Note that the terminal to be selected may be a terminal belonging to the selected group, or a terminal may be selected from a group other than the selected group. Also, by selecting a terminal that prohibits UL-OFDMA implementation within the group and setting the identifier of the selected terminal in the trigger frame, the selected terminal is prevented from performing resource unit selection and uplink transmission. It may be. The operation described here is merely an example, and various modifications of the operation are possible in order to realize the above-described first to 17th 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, the terminal designates an individual designation method for individually designating each terminal or a group designation method for designating a group. 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 as the group specification method, and when it is 0, it is determined as the individual specification method. Alternatively, the determination is made based on a predetermined field for setting information for identifying the group designation method or the individual designation method. A configuration in which the determination is performed by a method other than that described here is also possible. Details are as described above.

  When the individual designation method is designated (NO in S202), it is determined whether the own terminal is designated as a UL-OFDMA target terminal (S203). For example, when the AID of the own terminal is set in the AID field, it is determined that the own 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 specified 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 with the specified resource unit after a predetermined time from completion of reception of the trigger frame (S205). When conditions such as transmission packet length (PPDU length) and MCS are specified in the trigger frame, frame generation and transmission are performed 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 the own terminal 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 method thereof. For example, the group ID is set in the RA field (Address 1 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. Details are as described above. When the own terminal belongs to the above group, a resource unit is randomly selected from a plurality of candidate resource units (S207). Here, it may be determined whether there is a resource unit selection right between step S206 and step S207. For example, the number of resource units that are candidates for use is subtracted from the backoff counter value selected at random in advance, and the selection right is acquired when the resource unit becomes 0 or less, and the process proceeds to step S207. On the other hand, if it is greater than 0, the selection right is not acquired and the operation of this flow is terminated or the process returns to step S201. A plurality of candidate resource units are specified in the RU field or the like of the trigger frame. Also, when multiple group IDs are set in the trigger frame and different candidate resource units are specified for each group ID, the candidate resource units associated with the group ID to which the terminal belongs belong to Identify. Alternatively, a plurality of candidate resource units may be determined in advance by the system or specifications. Alternatively, when identification information for identifying a set of resource units that are a plurality of candidates is set in the trigger frame, correspondence information that associates the set identification information with the identification information and the resource unit group ( The candidate resource unit may be specified from the table. The correspondence information may be notified from the base station in advance. The number of resource units to be selected at random may be determined in advance, or information specifying the number 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 it with a resource unit selected at random after a predetermined time from completion of reception of the trigger frame (S205). When conditions such as transmission packet length (PPDU length) and MCS are specified in the trigger frame, frame generation and transmission are performed so as to satisfy the conditions.

  If it is determined in step S202 that a group ID has been specified, whether or not the own terminal belongs to the above group and whether or not a resource unit is individually specified for the own terminal. A configuration to check is also possible. In this case, the terminal uses the designated resource unit even when it belongs to the above group. In other words, when there is a resource unit designated for the terminal, the other terminal selects at random from the resource units that are candidates for the resource unit. Even when the own terminal belongs to the group, if it is designated as a UL-OFDMA prohibited target terminal, resource unit selection and uplink transmission are not performed. When a prohibition target terminal is specified for each resource unit, when selecting a resource unit at random, it is selected at random from resource units other than the specified resource unit. These details are as described above. The operation described here is merely an example, and various modifications of the operation are possible in order to realize the above-described first to 17th examples and combinations thereof.

  As described above, according to the present embodiment, when the presence or absence of an uplink request or the like can be accurately grasped, efficient communication is performed by designating a resource unit for each terminal. By designating with the group ID, the number of terminals that are transmission candidates is moderately suppressed, and the possibility that a plurality of terminals use the same resource unit at the same time is reduced, thereby suppressing a decrease in resource efficiency. In addition, when UL-OFDMA is performed when the presence / absence of a power-saving terminal, the presence / absence of an uplink transmission request, or the like is not sufficiently determined, by specifying a group ID, each terminal The resource utilization efficiency can be expected to be higher than when specifying. In particular, this effect is considered to be enhanced when the number of terminals belonging to the group is larger than the number of terminals specified when individually specifying. However, if the number of terminals is too large, the probability of collision between terminals in the resource unit increases, so that the number of resource units and resource units belonging to the group are sufficiently large compared to the number of terminals belonging to the group. You may adjust the relationship between numbers. As an example, the number of resource units is adjusted so that the number of resource units is 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, 2 ^ (number of terminals belonging to the group ID) -1 or a larger number of resource units may be used (for example, assuming 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 be 15 (= 2 ^ 4-1) or more. As described above, it may be combined with other methods that limit the number of terminals that can access the resource unit with terminals belonging to the same group. In the present embodiment, the same frame format (FIG. 10 and the like) can be used for the individual designation method and the group designation method.

  In the present embodiment, the trigger frame of the same format is divided into a plurality of different forms (for example, a form in which resource units are individually specified for each terminal, and a resource unit used by a terminal by specifying a group ID is randomly selected on the terminal side. However, even if the frame format of the trigger frame has any one form, there is no problem.

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

(Second Embodiment)
FIG. 21 is a functional block diagram of a base station (access point) 400 according to the second embodiment. The access point includes a communication processing unit 401, a transmission unit 402, a reception unit 403, antennas 42A, 42B, 42C, and 42D, a network processing unit 404, a wired I / F 405, and a memory 406. . Access point 400 is connected to server 407 via wired I / F 405. The communication processing unit 401 has the same functions 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 that of the upper processing unit 90 described in the first embodiment. Here, the communication processing unit 401 may have a buffer for exchanging data with the network processing unit 404. The 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 communication processing and application layer processing above the MAC layer, such as TCP / IP and UDP / IP. The operation of the network processing unit may be performed by software (program) processing by a processor such as a CPU, may be performed by hardware, or may be performed by both software and hardware.

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

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

  The wired I / F 405 transmits / receives data to / from the server 407. In this embodiment, communication with the server 407 is performed by wire, but communication with the server 407 may be performed wirelessly. 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. For example, an HTTP server (Web server), an FTP server, or the like is assumed. However, the present invention is not limited to this as long as it has a function of returning the requested data. A communication device operated by a user such as a PC or a smartphone may be used.

  When a STA belonging to the BSS of the base station 400 issues a data transfer request to the server 407, a packet related to the data transfer request is transmitted to the base station 400. The base station 400 receives this packet via the antennas 42A to 42D, and the receiving unit 403 performs physical layer processing and the communication processing unit 401 performs 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 the data transfer request (for example, data existing in the URL requested by the HTTP GET request) Whether it is cached (stored) in the memory 406 is confirmed. The memory 406 stores a table in which a URL (or a reduced expression thereof, such as 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 there is no cache data in the memory 406, the network processing unit 404 transmits a data transfer request to the server 407 via the wired I / F 405. That is, the network processing unit 404 transmits a data transfer request to the server 407 on behalf of the STA. Specifically, the network processing unit 404 generates an HTTP request, performs protocol processing such as addition of 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 that is a response to the data transfer request. The network processing unit 404 recognizes that the packet is addressed to the STA from the IP header of the packet received via the wired I / F 405 and passes the packet to the communication processing unit 401. The communication processing unit 401 performs MAC layer processing and the like on the packet, and the transmission unit 402 performs physical layer processing and the like, and transmits packets addressed to the STA from the antennas 42A to 42D. Here, the network processing unit 404 stores the data received from the server 407 as cache data in the memory 406 in association with the URL (or a reduced representation thereof).

  When cache data exists in the memory 406, the network processing unit 404 reads 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 (the destination port number of the packet transmitted by the communication terminal). Therefore, when viewed from the STA, it looks as if it is communicating with the server 407. The communication processing unit 401 performs MAC layer processing and the like on the packet, and the transmission unit 402 performs physical layer processing and the like, and transmits packets 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 traffic between the server 407 and the base station 400 can be reduced. Note that the operation of the network processing unit 404 is not limited to the operation of this embodiment. A general cache proxy that obtains 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. In other words, there is no problem with other operations.

In the present embodiment, a base station having a cache function has been described. However, a terminal (STA) having a cache function can be realized with the same block configuration as FIG. In this case, the wired I / F 405 may be omitted. (Variation is described here)
(Third embodiment)
FIG. 22 shows an example of the overall configuration of a terminal or a 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 equal to or greater than 1), 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 through the host interface. In addition to being connected to the host system 149 via a connection cable, the host system 149 may be directly connected. In addition, a configuration in which the wireless LAN module 148 is mounted on a substrate with solder or the like and is connected to the host system 149 via wiring on the substrate is 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 installed in the wireless LAN module 148, and the host system 149 may execute only higher-layer protocols. In this case, the configuration of the host system 149 can be simplified. This terminal is, for example, a mobile terminal, TV, digital camera, wearable device, tablet, smartphone, game device, network storage device, monitor, digital audio player, web camera, video camera, project, navigation system, external adapter, internal It may be an adapter, set top box, gateway, printer server, mobile access point, router, enterprise / service provider access point, portable device, handheld device, and the like.

  FIG. 23 shows a hardware configuration example of the wireless LAN module. This configuration can be applied when the wireless communication apparatus is installed in either a non-base station terminal or a base station. That is, it can be applied as an example of a specific configuration of the wireless communication apparatus illustrated 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 transmission systems (216, 222 to 225), reception systems (232 to 235), PLL 242, crystal oscillators (reference signal sources) 243 and switches 245 are arranged corresponding to each antenna. Each set may be connected to the control circuit 212. The PLL 242 or the crystal oscillator 243 or both 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. Further, 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 disposed on the RF IC 221 or may be disposed on another IC. Further, both or either of the memory 213 and the CPU 215 may be arranged in an IC different from the baseband IC.

  The memory 213 stores data exchanged with the host system. In addition, 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. 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 nonvolatile memory such as NAND or MRAM.

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

  The CPU 215 is a processor that controls the baseband circuit 212 by executing a program. The baseband circuit 212 mainly performs MAC layer processing and physical layer processing. 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 adds a physical header to the frame to be transmitted as a physical layer process, encodes, encrypts, modulates, and so on. For example, two types of digital baseband signals (hereinafter, a digital I signal and a digital Q signal). Signal).

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

  The RF IC 221 is, for example, an RF analog IC, a high frequency IC, or both. 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. RF IC 221 is coupled to antenna 247 via 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 and / or multiplies the oscillation signal to generate a signal having a constant frequency synchronized with the phase of the input signal. The PLL 242 includes a VCO (Voltage Controlled Oscillator), and performs feedback control using the VCO based on an oscillation signal input from the crystal oscillator 243, thereby obtaining a signal having the constant frequency. The generated constant frequency signal is input to the mixer 223 and the mixer 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 to a radio frequency by using a constant frequency signal 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-ended signal). Although a balanced signal is handled in the RF IC 221, an unbalanced signal is handled from the output of the RF IC 221 to the antenna 247. Therefore, the balun 225 converts these signals.

  The switch 245 is connected to the transmission-side balun 225 during transmission, and is connected to the reception-side balun 234 or the RF IC 221 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 may exist, and the switch 245 may be controlled from the circuit.

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

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

  The ADC 217 in the baseband IC 211 AD converts the input signal from the RF IC 221. More specifically, the ADC 217 converts the I signal into a digital I signal and converts the Q signal into a digital Q signal. There may be a case where only one system signal is received without performing quadrature demodulation.

  When a plurality of antennas are provided, the number of ADCs corresponding to the number of antennas may be provided. Based on the digital I signal and digital Q signal, the baseband circuit 212 performs physical layer processing such as demodulation processing, error correction code processing, and physical header processing 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 implemented.

(Fourth embodiment)
FIGS. 24A and 24B are perspective views of a wireless communication terminal according to the fourth embodiment, respectively. 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 form 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 mounted on the terminals (including base stations) described so far can be used. A wireless communication terminal equipped with a wireless communication device is not limited to a notebook PC or 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, and the like.

  In addition, the wireless communication device mounted on the terminal (including the base station) can 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 main body 332. The memory card 331 uses a wireless communication device 335 for wireless communication with an external device (such as a wireless communication terminal and / or base station). In FIG. 25, the description of other elements (for example, a memory) in the memory card 331 is omitted.

(Fifth embodiment)
In the fifth embodiment, in addition to the configuration of the wireless communication apparatus according to any one of the embodiments described above, a bus, a processor unit, and an external interface unit are provided. The processor unit and the external interface unit are connected to the buffer via the bus. Firmware operates in the processor unit. As described above, by configuring the firmware to be included in the wireless communication device, it is possible to easily change the function of the wireless communication device by rewriting the firmware. The processor unit on which the firmware operates may be a processor that performs processing of the communication processing device or the control unit according to the present embodiment, or may be another processor that performs processing related to function expansion or change of the processing. Also good. The base station and / or the wireless communication terminal according to the present embodiment may include a processor unit on which firmware operates. Alternatively, the processor unit may be provided in an integrated circuit in a wireless communication device mounted on a base station or an integrated circuit in a wireless communication device mounted on a wireless communication terminal.

(Sixth embodiment)
In the sixth embodiment, a clock generation unit is provided in addition to the configuration of the wireless communication apparatus according to any one 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. Thus, the host side and the wireless communication apparatus side can be operated in synchronization by outputting the clock generated inside the wireless communication apparatus to the outside and operating the host side with the clock output to the outside. It becomes possible.

(Seventh embodiment)
In the seventh embodiment, in addition to the configuration of the wireless communication apparatus according to any one of the embodiments described above, a power supply unit, a power supply control unit, and a wireless power supply unit are included. The power supply control unit is connected to the power supply unit and the wireless power supply unit, and performs control to select a power supply to be supplied to the wireless communication device. As described above, by providing the wireless communication apparatus with the power supply, it is possible to perform a low power consumption operation by controlling the power supply.

(Eighth embodiment)
In the eighth embodiment, a SIM card is included in addition to the configuration of the wireless communication apparatus according to any one of the embodiments described above. 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 apparatus. As described above, by adopting a configuration in which the SIM card is provided in the wireless communication device, authentication processing can be easily performed.

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

(Tenth embodiment)
In the tenth embodiment, in addition to the configuration of the wireless communication apparatus according to any one of the embodiments described above, an LED unit is included. The LED unit is connected to, for example, 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. As described above, by providing the wireless communication device with the LED unit, it is possible to easily notify the user of the operation state of the wireless communication device.

(Eleventh embodiment)
In the eleventh embodiment, a vibrator unit is included in addition to the configuration of the wireless communication apparatus according to any one of the above-described embodiments. The vibrator unit is connected to, for example, 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. As described above, by providing the radio communication device with the vibrator unit, it is possible to easily notify the user of the operation state of the radio communication device.

(Twelfth embodiment)
In the twelfth embodiment, a display is included in addition to the configuration of the wireless communication device (a wireless communication device of a base station or a wireless communication device of a wireless communication terminal, or both) according to any one of the embodiments described above. The display may be connected to the MAC processing unit of the wireless communication device via a bus (not shown). Thus, it is possible to easily notify the user of the operation state of the wireless communication device by providing the display and displaying the operation state of the wireless communication device on the display.

(13th Embodiment)
In this embodiment, [1] a frame type in a wireless communication system, [2] a method of disconnecting connections between wireless communication apparatuses, [3] an access method of a wireless LAN system, and [4] a frame interval of the wireless LAN will be described.
[1] Frame type in communication system Generally, as described above, the frames handled on the radio access protocol in the radio communication system are roughly divided into three: data frame, management frame, and control frame. Divided into types. These types are usually indicated by a header portion provided in common between frames. As a display method of the frame type, three types may be distinguished by one field, or may be distinguished by a combination of two fields. In the IEEE 802.11 standard, the frame type is identified by two fields, Type and Subtype, in the Frame Control field in the frame header portion of the MAC frame. A data frame, a management frame, or a control frame is roughly classified in the Type field, and a detailed type in the roughly classified frame, for example, a Beacon frame in the management frame is identified in the Subtype field.

  The management frame is a frame used for managing a physical communication link with another wireless communication apparatus. 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), 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. Data is generated in an upper layer of the present embodiment, for example, generated by a user operation.

  The control frame is a frame used for control when a data frame is transmitted / received (exchanged) to / from another wireless communication apparatus. When the wireless communication apparatus receives a data frame or a management frame, the response frame transmitted for confirmation of delivery belongs to the control frame. The response frame is, for example, an ACK frame or a BlockACK frame. RTS frames and CTS frames are also control frames.

  These three types of frames are sent out via the antenna as physical packets after undergoing processing as required in the physical layer. Note that in the IEEE 802.11 standard (including the above-mentioned extended standard such as 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 receiving wireless communication terminal is requested to transmit an ACK frame that is a response frame. Is a control frame.

[2] Connection disconnection method between wireless communication devices There are an explicit method and an implicit method for disconnection (release) of a connection. As an explicit method, one of the wireless communication apparatuses that have established a connection transmits a frame for disconnection. In the IEEE 802.11 standard, a deauthentication frame is classified as a management frame. Normally, when a wireless communication device that transmits a frame for disconnecting a connection transmits the frame, the wireless communication device that receives a frame for disconnecting a connection disconnects the connection when the frame is received. judge. After that, if it is a non-base station wireless communication terminal, it returns to the initial state in the communication phase, for example, the state of searching for a connected BSS. When the 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 the wireless communication terminal that subscribes to its own BSS, the connection management Delete information related to the wireless communication terminal from the table. For example, when assigning an AID to a wireless communication terminal that joins the BSS in the association process at the stage where the wireless communication base station has permitted the connection, the holding information associated with the AID of the wireless communication terminal that has disconnected the connection. May be deleted, and the AID may be released and assigned to another newly joined wireless communication terminal.

  On the other hand, as an implicit method, a frame transmission (transmission of a data frame and a management frame, or transmission of a response frame to a frame transmitted by the device itself) is detected from a wireless communication device of a connection partner with which a connection has been established. If not, it is determined whether the connection is disconnected. There is such a method in the situation where it is determined that the connection is disconnected as described above, such that the communication distance is away from the connection-destination wireless communication device, and the wireless signal cannot be received or decoded. This is because a wireless link cannot be secured. That is, it is impossible to expect reception of a frame for disconnecting the connection.

  As a specific example of determining the disconnection by an implicit method, a timer is used. 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 a retransmission period of the frame is started, and until the first timer expires (that is, If a delivery confirmation response frame is not received (until the desired retransmission period elapses), retransmission is performed. The first timer is stopped when a delivery confirmation response frame to the frame is received.

  On the other hand, when the first timer expires without receiving the delivery confirmation response frame, for example, it is confirmed whether the other party's wireless communication device still exists (within the communication range) (in other words, the wireless link can be secured). And a second timer for limiting the retransmission period of the frame (for example, a retransmission timer for the management frame) is started at the same time. Similar to the first timer, the second timer also performs retransmission if it does not receive an acknowledgment frame for the frame until the second timer expires, and determines that the connection has been disconnected when the second timer expires. . When it is determined that the connection has been disconnected, a frame for disconnecting the connection may be transmitted.

  Alternatively, when a frame is received from the connection partner wireless communication device, the third timer is started. Whenever a new frame is received from the connection partner wireless communication device, the third timer is stopped and started again from the initial value. When the third timer expires, a management frame is transmitted to confirm whether the other party's wireless communication device still exists (within the communication range) (in other words, whether the wireless link has been secured) as described above. At the same time, a second timer (for example, a retransmission timer for management frames) that limits the retransmission period of the frame is started. Also in this case, if the acknowledgment response frame to the frame is not received until the second timer expires, retransmission is performed, and if the second timer expires, it is determined that the connection has been disconnected. In this case as well, a frame for disconnecting the connection may be transmitted when it is determined that the connection has been disconnected. The latter management frame for confirming whether the wireless communication apparatus of the connection partner still exists may be different from the management frame in the former case. In the latter case, the timer for limiting the retransmission of the management frame is the same as that in the former case as the second timer, but a different timer may be used.

[3] Access method of wireless LAN system For example, there is a wireless LAN system that is assumed to communicate or compete with a plurality of wireless communication devices. The IEEE 802.11 wireless LAN uses CSMA / CA (Carrier Sense Multiple Access with Carrier Avoidance) as a basic access method. In the method of grasping the transmission of a certain wireless communication device and performing transmission after a fixed time from the end of the transmission, the transmission is performed simultaneously by a plurality of wireless communication devices grasping the transmission of the wireless communication device, and as a result The radio signal collides and frame transmission fails. By grasping the transmission of a certain wireless communication device and waiting for a random time from the end of the transmission, the transmissions by a plurality of wireless communication devices that grasp the transmission of the wireless communication device are stochastically dispersed. Therefore, if there is one wireless communication device that has drawn the earliest time in the random time, the frame transmission of the wireless communication device is successful, and frame collision can be prevented. Since acquisition of transmission rights is fair among a plurality of wireless communication devices based on a random value, the method employing Carrier Aviation is a method suitable for sharing a wireless medium between a plurality of wireless communication devices. be able to.

[4] Wireless LAN Frame Interval The IEEE 802.11 wireless LAN frame interval will be described. The frame interval used in the IEEE 802.11 wireless LAN is as follows: distributed coordination function inter frame space (DIFS), arbitration inter frame speed (IFS), point co-indication frame interface (IFFS), point co-indication frame interface (IFS) , Reduced interface space (RIFS), and the like.

  In the IEEE802.11 wireless LAN, the frame interval is defined as a continuous period to be opened after confirming carrier sense idle before transmission, and a strict period from the previous frame is not discussed. Therefore, in the description of the IEEE802.11 wireless LAN system here, the definition follows. In the IEEE802.11 wireless LAN, the waiting time for random access based on CSMA / CA is the sum of a fixed time and a random time, and it can be said that such a definition is used to clarify the fixed time.

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

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

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

  The RIFS is a frame interval that can be used when a plurality of frames are continuously transmitted to the same wireless communication device in bursts after acquiring the access right once. Do not request a response frame.

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

  It is assumed that when a transmission request for a data frame (W_DATA1) is generated in a certain wireless communication apparatus, the medium is recognized as busy as a result of carrier sense. In this case, a fixed time AIFS is released from the point when the carrier sense becomes idle, and then a data frame W_DATA1 is transmitted to the communication partner when a random time (random backoff) is available. As a result of carrier sense, when the medium is not busy, that is, it is recognized that the medium is idle, a fixed time AIFS is released from the time when carrier sense is started, and the data frame W_DATA1 is transferred to the communication partner. Send to.

  The random time is obtained by multiplying a pseudo-random integer derived from a uniform distribution between a contention window (Content Window: CW) given by an integer from 0 to a slot time. Here, CW multiplied by slot time is referred to as CW time width. The initial value of CW is given by CWmin, and every time retransmission is performed, the value of CW is increased until it reaches CWmax. Both CWmin and CWmax have values for each access category, similar to AIFS. In the wireless communication apparatus that is the transmission destination of W_DATA1, if the data frame is successfully received and the data frame is a frame that requests transmission of a response frame, the occupation of the physical packet that includes the data frame on the wireless medium is completed. A response frame (W_ACK1) is transmitted after SIFS time from the time. The wireless communication apparatus that has transmitted W_DATA1 transmits the next frame (for example, W_DATA2) after SIFS time from the end of occupation of the physical packet containing W_ACK1 on the wireless medium if it is within the transmission burst time limit when W_ACK1 is received. can do.

  AIFS, DIFS, PIFS, and EIFS are functions of SIFS and slot time. SIFS and slot time are defined for each physical layer. Also, parameters such as AIFS, CWmin, and CWmax that can be set for each access category can be set for each communication group (Basic Service Set (BSS) in the IEEE802.11 wireless LAN), but default values are set. .

  For example, in the 802.11ac standard formulation, the SIFS is 16 μs and the slot time is 9 μs. Accordingly, the PIFS is 25 μs, the DIFS is 34 μs, and the frame interval of the access category BACKGROUND (AC_BK) in AIFS is 79 μs by default. The frame interval of BEST EFFORT (AC_BE) has a default value of 43 μs, the frame interval of VIDEO (AC_VI) and VOICE (AC_VO) has a default value of 34 μs, and the default values of CWmin and CWmax are 31 and 1023 for AC_BK and AC_BE, respectively. , AC_VI is 15 and 31, and AC_VO is 7 and 15. Note that the EIFS is basically the sum of the time lengths of response frames in the case of transmission at SIFS and DIFS at the slowest required physical rate. Note that in a wireless communication apparatus capable of efficiently taking EIFS, the occupation time length of a physical packet carrying a response frame to the physical packet that activated EIFS is estimated, and the sum of SIFS, DIFS, and the estimated time may be used. it can.

  The terms used in this embodiment should be interpreted widely. For example, the term “processor” may include general purpose processors, central processing units (CPUs), microprocessors, digital signal processors (DSPs), controllers, microcontrollers, state machines, and the like. In some situations, a “processor” may refer to an application specific integrated circuit, a field programmable gate array (FPGA), a programmable logic circuit (PLD), or the like. “Processor” may refer to a combination of processing devices such as a plurality of microprocessors, a combination of a DSP and a microprocessor, and one or more microprocessors that cooperate with a DSP core.

  As another example, the term “memory” may encompass any electronic component capable of storing electronic information. “Memory” means 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 can be read by the processor. If the processor reads and / or writes information to the memory, the memory can be said to be in electrical communication with the processor. The memory may be integrated into the processor, which again can be said to be in electrical communication with the processor.

  Note that the frame described in each embodiment may refer to not only a frame called in the IEEE 802.11 standard, but also a packet called a packet such as a Null Data Packet. When it is expressed that a base station transmits or receives a plurality of frames or a plurality of Xth frames, these frames or the Xth frames may be the same (for example, the same type or the same content) or different. . X can be set to any value depending on the situation. The plurality of frames or the plurality of Xth frames may be transmitted or received at different timings as well as those transmitted or received at the same time. In addition, when expressing that the first frame, the second frame, etc. are transmitted or received at different points in time, the first, second, etc. expressions are merely expressions for distinguishing frames, and these There is no difference in the type and content of the frame.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

Claims (20)

A transmitter that includes information specifying a plurality of frequency components, and that transmits a first frame instructing implementation of frequency multiplex transmission by a plurality of wireless communication terminals;
A receiving unit that receives a second frame at at least one frequency component of the plurality of frequency components, and
The first frame includes a first form in which each terminal identifier of the plurality of wireless communication terminals is specified in association with at least one of the plurality of frequency components, and a group of groups to which the plurality of wireless communication terminals belong A wireless device having one of the second forms of specifying an identifier. The first frame includes a first field for designating a destination address and a second field for designating a source address,
When the first frame is in the first form, a broadcast address or a multicast address is set in the first field, an address of the own device is set in the second field,
When the first frame is in the second form, the group identifier is set in the first field, and a value obtained by converting a bit at a specific position of the address of the own device is set in the second field. The wireless device according to 1. The first frame includes a first field for designating a destination address, and a plurality of third fields for designating a pair of information designating the frequency component and the wireless communication terminal,
A broadcast address or a multicast address is set in the first field of the first frame;
When the first frame is in the first form, a pair of the frequency component identifier and the terminal identifier of the wireless communication terminal is set in each of the plurality of third fields,
The radio apparatus according to claim 1, wherein when the first frame is in the second form, a pair of the frequency component identifier and the group identifier is set in each of the plurality of third fields. The first frame includes a fourth field;
The wireless device according to claim 3, wherein information specifying one of the first form and the second form is set in the fourth field. The first frame includes a fifth field for designating a source address;
When the first frame is in the first form, the address of the own apparatus is set in the fifth field, and in the case of the second form, the specific position of the address of the own apparatus is set in the fifth field. The wireless device according to claim 3, wherein a value obtained by converting bits is set. The wireless device according to any one of claims 1 to 5, wherein the group identifier identifies a group of wireless communication terminals to which a terminal identifier is not assigned by the own device. The wireless device according to any one of claims 1 to 5, wherein the group identifier is a multicast address. The radio apparatus according to claim 1, further comprising at least one antenna.   The radio apparatus according to any one of claims 1 to 8, which is a radio base station. The radio apparatus according to claim 1, wherein communication is controlled according to the IEEE 802.11 standard. A wireless communication method using a wireless communication terminal,
Transmitting a first frame that includes information designating a plurality of frequency components and instructing the implementation of frequency multiplex transmission by a plurality of wireless communication terminals;
Receiving a second frame with at least one frequency component of the plurality of frequency components, wherein the first frame includes a terminal identifier of each of the plurality of radio communication terminals, at least one of the plurality of frequency components; A wireless communication method comprising: a first form that is specified in association with a second form; and a second form that specifies a group identifier of a group to which the plurality of wireless communication terminals belong. A receiver that includes information specifying a plurality of frequency components, and that receives a first frame that instructs execution of frequency multiplex transmission by a plurality of wireless communication terminals;
A transmitter that transmits a second frame using at least one frequency component of the plurality of frequency components after a first time from completion of reception of the first frame;
The first frame includes a first form in which each terminal identifier of the plurality of wireless communication terminals is specified in association with at least one of the plurality of frequency components, and a group of groups to which the plurality of wireless communication terminals belong Having one of the second forms of designating an identifier;
The transmitting unit, when the first frame has the first form, when the terminal identifier of the own apparatus matches at least one of the terminal identifiers of the plurality of wireless communication terminals. Transmitting the second frame using the at least one frequency component associated with a terminal identifier of
When the second frame has the second form, if the group identifier indicates a group to which the device belongs, the at least one frequency component is selected from the plurality of frequency components, and the selected frequency component is A wireless device for transmitting the second frame using. The first frame includes a first field for designating a destination address and a second field for designating a source address;
When the first frame is in the first form, a broadcast address or a multicast address is set in the first field, a source address of the first frame is set in the second field,
When the first frame is in the second form, the group identifier is set in the first field, and a value obtained by converting a bit at a specific position of the source address of the first frame is set in the second field. The wireless device according to claim 12. The first frame includes a first field for designating a destination address, and a plurality of third fields for designating a pair of information designating the frequency component and the wireless communication terminal,
A broadcast address or a multicast address is set in the first field of the first frame;
When the first frame is in the first form, a pair of the frequency component identifier and the terminal identifier of the wireless communication terminal is set in each of the plurality of third fields, and the first frame is the first frame. The radio apparatus according to claim 12, wherein, in the case of two forms, a pair of the frequency component identifier and the group identifier is set in each of the plurality of third fields. The first frame includes a fourth field;
The wireless device according to claim 14, wherein information for designating either the first form or the second form in the first frame is set in the fourth field. The first frame includes a fifth field for designating a source address;
When the first frame is in the first form, the source address of the first frame is set in the fifth field, and in the second form, the fifth field is the first frame of the first frame. The wireless device according to claim 14, wherein a value obtained by converting a bit at a specific position of a transmission source address is set. The wireless device according to any one of claims 12 to 16, wherein the group identifier for identifying a group of wireless communication terminals to which a terminal identifier is not assigned by a transmission source of the first frame is set in the first frame. . The wireless device according to claim 12, wherein the group identifier is a multicast address. The radio apparatus according to claim 12, further comprising at least one antenna.   The radio apparatus according to any one of claims 12 to 19, which is a non-radio base station.

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