WO2016080408A1

WO2016080408A1 - Wireless communication terminal, wireless communication method, and wireless communication system

Info

Publication number: WO2016080408A1
Application number: PCT/JP2015/082307
Authority: WO
Inventors: 浩樹森; 寿久鍋谷
Original assignee: 株式会社東芝
Priority date: 2014-11-18
Filing date: 2015-11-17
Publication date: 2016-05-26
Also published as: JP2018011093A

Abstract

[Problem] To efficiently schedule uplink multi-user transmission. [Solution] A wireless communication terminal according to an embodiment of the present invention is equipped with at least one antenna, a wireless communication unit for transmitting and receiving frames through the antenna, and a control unit. Therein, the control unit: receives a first frame requesting transmission permission via the wireless communication unit; according to receipt of the first frame, transmits, via the wireless communication unit, a second frame asking whether there is a transmission request in a second terminal differing from the first terminal which transmitted the first frame; receives a third frame reporting whether the transmission request is present via the wireless communication unit; on the basis of the first and third frames, transmits, via the wireless communication unit, a fourth frame specifying a third terminal permitting transmission; and after completing transmission of the fourth frame, receives a fifth frame via the wireless communication unit.

Description

Wireless communication terminal, wireless communication method, and wireless communication system

Embodiments described herein relate generally to a wireless communication terminal, a wireless communication method, and a wireless communication system.

In a wireless LAN system, a protocol for supporting a method in which a plurality of wireless terminals perform simultaneous transmission on the uplink is being studied. As a method in which a plurality of wireless terminals simultaneously transmit in the uplink, uplink multi-user MIMO (Uplink Multi-User MIMO: UL-MU-MIMO) transmission and uplink multi-user multi-channel (Uplink Multi-User Multi-Multi) are available. (Channel) transmission is known. Hereinafter, these methods may be collectively referred to as uplink multi-user (UL-MU) transmission. As triggers for invoking UL-MU transmission, a central control type where an access point generates a trigger and a distributed control type where a wireless terminal generates a trigger have been proposed.

In the central control method, an access point provides a solicitation period before the start of UL-MU transmission, and a wireless terminal desiring to execute UL-MU transmission can send information necessary for UL-MU transmission to the access point during this solicitation period. To be notified. In this method, overhead before the start of UL-MU transmission increases, and there is a possibility that a notification of hope for UL-MU transmission from the wireless terminal does not come within the recruitment period. In this case, system efficiency is reduced. In addition, since it is unknown whether there is a wireless terminal that desires to execute UL-MU transmission, it is difficult to determine the timing for executing UL-MU transmission.

In the distributed control method, when an access point receives an uplink transmission request from a certain wireless terminal, a wireless terminal included in the group is broadcast by broadcasting a frame including a group ID of the group to which the wireless terminal belongs as a trigger frame. (Up to 4 terminals in IEEE 802.11ac) UL-MU transmission is performed. Compared to the central control method, overhead before the start of UL-MU transmission can be greatly reduced. However, since the access point does not collect requests from wireless terminals other than the wireless terminal that initially made the uplink transmission request, In response to the request from the wireless terminal that made the uplink transmission request, other wireless terminals need to perform uplink transmission. In this case, the data transmission may not be efficient for other wireless terminals.

As described above, neither the central control type nor the distributed control type can efficiently perform uplink multiuser transmission scheduling with a small overhead.

IEEE 802.11-14 / 0598r0

An embodiment of the present invention aims to efficiently schedule uplink multiuser transmission.

A wireless communication terminal as an embodiment of the present invention includes at least one antenna, a wireless communication unit that transmits and receives a frame via the antenna, and a control unit. The control unit receives a first frame requesting permission for transmission via the wireless communication unit, and transmits the first frame via the wireless communication unit in response to reception of the first frame. A second frame for inquiring whether there is a request for z-delayed transmission to a second terminal different from the first terminal, and receiving a third frame for notifying whether there is a request for transmission via the wireless communication unit, Based on the first frame and the third frame, a fourth frame designating the third terminal permitted to transmit is transmitted via the wireless communication unit, and after the transmission of the fourth frame is completed, the wireless The fifth frame is received via the communication unit.

The figure which shows the radio | wireless communications system which concerns on 1st Embodiment. Explanatory drawing of the outline | summary of UL-MU-MIMO transmission and UL-MU-MC transmission. The figure which shows the example of the operation | movement sequence between an access point and a radio | wireless terminal. The figure which shows the basic form of the frame format of a MAC frame. The figure which shows the example of a terminal information field. The figure which shows the format example of a physical packet. The functional block diagram of the radio | wireless communication apparatus mounted in an access point. The functional block diagram of the radio | wireless communication apparatus mounted in a radio | wireless terminal. The flowchart of operation | movement of the access point which concerns on 1st Embodiment. 6 is a flowchart showing the operation of the wireless terminal according to the first embodiment. The figure which shows the other example of the operation | movement sequence between an access point and a radio | wireless terminal. The figure which shows the example of grouping information. The figure which shows the example of a response terminal field and a group ID field. The figure which shows the further another example of the operation | movement sequence between an access point and a radio | wireless terminal. The figure which shows the further another example of the operation | movement sequence between an access point and a radio | wireless terminal. The figure which shows the example of whole structure of a terminal or an access point. The figure which shows the hardware structural example of the radio | wireless communication apparatus mounted in an access point or a terminal. The perspective view of the radio | wireless apparatus which concerns on 8th Embodiment. The figure which shows the memory card based on 8th Embodiment. The figure which shows an example of the frame exchange of a contention period. The figure for demonstrating allocation of a resource unit. The figure for demonstrating the form of a resource unit.

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

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

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

The wireless communication system in FIG. 1 is a wireless network including an access point (AP) 11 and a plurality of

wireless terminals

1, 2, 3, and 4. The access point 11 is also a form of a wireless terminal, but differs from the wireless terminals 1 to 4 in having a relay function. The access point 11 and each of the wireless terminals 1 to 4 communicate according to an arbitrary wireless standard. Here, it shall conform to the IEEE 802.11 standard. In the IEEE 802.11 standard, CSMA / CA (Carrier Sense Multiple Access / Collision Avidance) is used as an access control method. In order for the wireless terminals 1 to 4 to belong to the network (BSS: Basic Service Set) formed by the access point 11, the wireless terminal 1 establishes a wireless link by performing an association process with the access point 11 and an authentication process as necessary. There is a need. The wireless terminals 1 to 4 establish a wireless link with the access point 11 to exchange parameters necessary for communication and grasp each other's capabilities.

The access point 11 includes a plurality of antennas. In the example of FIG. 1, the access point 11 includes four

antennas

12A, 12B, 12C, and 12D. The access point 11 is equipped with a device (wireless communication device) for wireless communication with the wireless terminals 1 to 4. The device (wireless communication device) includes a wireless communication unit or an RF integrated circuit that transmits and receives signals to and from wireless terminals 1 to 4, and a plurality of wireless terminals by transmitting and receiving frames to and from wireless terminals 1 to 4 via the wireless communication unit. And a control unit or a baseband integrated circuit for controlling communication with 1 to 4.

Each of the wireless terminals 1 to 4 includes one or a plurality of antennas, and in the example of FIG. 1, each of the wireless terminals 1 to 4 includes one

antenna

1A, 2A, 3A, and 4A. Each wireless terminal is equipped with a device (wireless communication device) for wireless communication with the access point 11. The device (wireless communication device) controls communication with the access point 11 by transmitting / receiving a frame to / from the access point 11 via a wireless communication unit or an RF integrated circuit that transmits / receives a signal to / from the access point 11. A control unit or a baseband integrated circuit.

The access point 11 forms a wireless network (referred to as a first network), and a wireless terminal that communicates with the access point 11 needs to belong to this wireless network. The access point 11 may be connected to another wired or wireless network (referred to as a second network) different from the wireless network. The access point 11 relays communication between the first network and the second network, or relays communication between a plurality of wireless terminals belonging to the first network. The access point 11 transmits the data frame received from each of the wireless terminals 1 to 4 to the wireless terminal in addition to the same first network or transfers it to a second network different from the first network, depending on the destination. To do.

In the present embodiment, when a plurality of wireless terminals transmit a data frame including data generated in its own device to the access point 11, it is possible to transmit the data frame using an uplink multi-user (Uplink Multi-User) method. Uplink multi-user schemes include uplink multi-user MIMO (Uplink Multi-User MIMO: UL-MU-MIMO) or uplink orthogonal frequency division multiple access (UL-OFDMA: Uplink Orthogonal Division Multiple Access). . UL-OFDMA includes resource unit-based UL-OFDMA and channel-based UL-OFDMA. The latter is sometimes referred to as uplink multi-user multi-channel (UL-MU-MC). The UL-MU transmission performed in this embodiment may be any of these schemes.

Fig. 2 (A) shows the outline of UL-MU-MIMO transmission. A plurality of wireless terminals 1 to 4 (STA1 to STA4) simultaneously transmit frames to the access point (AP) in the same frequency band (channel 1 in the figure). The access point receives these frames at the same time and separates them into frames of each wireless terminal by performing MIMO demodulation. In UL-MU-MIMO transmission, frames can be transmitted simultaneously from a plurality of wireless terminals, so that system throughput can be improved. The maximum number of data streams that can be multiplexed for UL-MU-MIMO transmission is limited by the number of antennas at the access point. In the case of the example in FIG. 1, since the access point 11 has four antennas, the maximum number of streams that can be multiplexed is four. When each wireless terminal has one antenna and can transmit only one data stream, each access point can simultaneously communicate with up to four terminals. A single wireless terminal can be equipped with a plurality of antennas to transmit a plurality of data streams (MIMO transmission).

Figure 2 (B) shows an overview of UL-MU-MC transmission. An access point (AP) assigns a plurality of channels 1 to 4 to a plurality of wireless terminals 1 to 4 (STA1 to 4), respectively, and simultaneously transmits from the plurality of wireless terminals 1 to 4 on the assigned channels. That is, wireless terminals 1 to 4 perform OFDMA (Orthogonal Frequency Division Multiple Access) transmission using channels 1 to 4, respectively. The channels assigned to each wireless terminal are different from each other. The plurality of channels used in OFDMA transmission may be all channels used as a wireless communication system or some of the channels. One or more channels may be allocated to each wireless terminal. When a plurality of channels are allocated, the allocated channels may be channels that are continuous in the frequency domain or channels that are separated from each other. If eight channels that can be allocated exist and one channel is allocated to one wireless terminal, the maximum number of terminals that can communicate simultaneously is eight. The access point extracts a channel signal for each wireless terminal from a frame received simultaneously from each wireless terminal by filtering or the like, and performs processing of the physical layer including demodulation and decoding on the extracted signal to each wireless terminal. Get the frame sent by.

On the other hand, in resource unit based OFDMA, resource units (which may be called subchannels, resource blocks, frequency blocks, etc.) including one or a plurality of subcarriers are allocated to terminals as communication resources, Communicate simultaneously with other terminals.

Resource unit is a frequency component that is the minimum unit of resources for communication. FIG. 21 shows resource units (RU # 1, RU # 2,... RU # K) secured in a continuous frequency region in 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 more 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 resource unit or each subcarrier in the channel may be set with identification information for identifying the resource unit or 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. Multiple terminals simultaneously use different resource units, thereby realizing OFDMA communication.

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. 22 schematically shows an example of an arrangement pattern of resource units in one channel. The horizontal direction along the plane of the paper corresponds to the frequency domain direction. FIG. 22A shows an example in which a plurality of resource units (RU # 1, RU # 2,... RU # K) having the same bandwidth are arranged. FIG. 22B 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. 22C shows an example in which resource units having three or more bandwidths are arranged. The resource units (RU # 12-1, RU # 12-2) have the largest bandwidth, and the resource unit RU # 11- (L-1) has the same bandwidth and resources as the resource unit of FIG. The units (RU # K-1, RU # K) have the same bandwidth as the resource unit in FIG.

The number of resource units that each terminal uses in OFDMA is one or more, and is not limited to a specific value. When a terminal uses a plurality of resource units, a plurality of resource units that are continuous in frequency may be bonded to be used as one resource unit, or a plurality of resource units in remote locations may be used. Also good. Resource unit # 11-1 in FIG. 22B may be considered as an example of a resource unit in which resource units # 1 and # 2 in FIG.

サブ Subcarriers in one resource unit may be continuous in the frequency domain, or a resource unit may be defined from a plurality of subcarriers arranged discontinuously. The number of channels used in OFDMA is not limited to one. In addition to channel M, another channel (see channel N in FIG. 21) arranged at a position distant from the frequency domain may be used in the same manner as channel M. 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 one channel 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. It is also possible to consider channel M and channel N as one 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. 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 Asset) busy / idle physical carrier sense (Physical Carrier Sense) and virtual carrier sense based on the media reservation time described in the received frame (Virtual Carrier Sense). Sense) may be included. A mechanism for virtually determining that a medium is busy, such as the latter, or a period during which a medium is virtually busy is referred to as 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 may be determined as idle.

It should be noted that a scheme combining UL-MU-MIMO and UL-OFDMA (UL-MU-MIMO & OFDMA) may be executed as uplink multi-user communication. UL-OFDMA & MU-MIMO performs MU-MIMO transmission for each resource unit or channel by using the same resource unit or channel between a plurality of terminals.

As described above, the access point 11 and the wireless terminals 1 to 4 establish wireless links to exchange parameters necessary for communication and grasp each other's capabilities. Therefore, the access point 11 establishes a wireless link with the wireless terminals 1 to 4 so that the wireless terminals 1 to 4 can perform UL-MU-MIMO transmission or UL-OFDMA (channel-based UL-OFDMA (UL-MU- MC) or resource unit based UL-OFDMA) transmission can be grasped. However, ascertaining the capability of supporting UL-MU-MIMO transmission or UL-MU-MC (channel-based UL-OFDMA (UL-MU-MC) or resource unit-based UL-OFDMA) transmission is not possible. After establishment, it is also possible to grasp by transmitting / receiving management frames and the like. In FIG. 1, wireless terminals 1 to 4 are shown. However, in addition to the illustrated wireless terminals 1 to 4, there may be other wireless terminals that establish a wireless link with the access point 11.

FIG. 3 shows an example of an operation sequence between the access point 11 and the wireless terminals 1 to 3 shown in FIG. Assume that the wireless terminals 1 to 4 each have data to be transmitted to the access point 11 and perform UL-MU transmission from the wireless terminals 1 to 4 to the access point 11.

In the figure, the section indicated by a solid arrow extending in the horizontal direction represents a short interframe space (SIFS), and the section indicated by a thick arrow is a distributed coordination function interframe (DIFS) and CSMA / CA backoff. This represents the total (carrier sense time) with (BackOff) time. However, SIFS and DIFS are examples, and other times (frame intervals) may be used as long as they are predetermined times. Details of SIFS and DIFS will be described in another embodiment.

In the operation sequence example of FIG. 3, a request phase (Request Phase) from the transmission of the request frame 21 by the wireless terminal 1 to the completion of the transmission of the notification frame 28 by the access point 11 and the BlockACK frame after the transmission of the notification frame 28 is completed. It has a data transmission phase (Data Transmission Phase) until transmission is completed. As will be described later, in the request phase, each wireless terminal transmits a request frame as a response to the inquiry frame 22 or the polling frame transmitted from the access point. That is, the access point causes each wireless terminal to transmit a request frame by central control type access control.

When data for uplink transmission is generated in the wireless terminal 1, the wireless terminal 1 transmits a request frame 21 for requesting permission for data transmission to the access point 11 in order to request transmission by UL-MU transmission. In order to transmit the request frame 21, the wireless terminal 1 performs carrier sense during DIFS and a randomly determined backoff time, and acquires a transmission right. The wireless terminals 2 to 4 also have data for uplink transmission, and each attempt to acquire a transmission right for transmitting a request frame. Here, it is assumed that the wireless terminal 1 has acquired the transmission right. The wireless terminal 1 transmits a request frame 21 during TXOP (Transmission Opportunity). The request frame 21 is a frame that triggers the access point 11 to execute the UL-MU transmission, and may be referred to as a trigger request frame. A wireless terminal that has transmitted a trigger request frame may be referred to as a trigger terminal.

Here, the request frame can be defined based on a general MAC frame format. FIG. 4 shows the basic form of the MAC frame format. The basic form of the MAC frame format consists of a frame control field, a duration field, an address field 1 to 3, a sequence control field, an address 4 field, a data field, and a check-sum field. Have. FIG. 4 shows a general frame structure, and some fields may not exist depending on the frame.

In the frame control field, a type (Type) field for distinguishing three frame types of a data frame (Data frame), a management frame (Management frame), and a control frame (Control frame) is provided. In order to distinguish more detailed frame types, a subtype field is provided in the frame control field. In the case of a request frame, for example, the type is a value representing a control frame, and the value of the subtype is a value newly defined for the request frame. However, a configuration in which the frame type of the request frame is not a control frame but a management frame or a data frame is not excluded. Details of the control frame, the management frame, and the data frame will be described in another embodiment.

The media reservation time is set in the duration field. When a frame addressed to another wireless terminal (not addressed to itself) is received, it is determined that the medium is virtually busy over the medium reservation time. 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). In the sequence control field, a frame sequence number and the like are set.

In the address 1 field, set the receiving address (RA) of the frame. Since the access destination of the request frame is the access point 11, the address of the access point 11 is set in the address 1 field. The address of the access point 11 is specifically the MAC address or BSSID of the access point 11. The address (TA) of the frame transmission source is set in the address 2 field. Since the transmission source of the request frame is the wireless terminal 1, the MAC address of the wireless terminal 1 may be set in the address 2 field. In the checksum field, FCS (Frame Check Sequence) information is set as a checksum code used for detecting an error in the frame body portion on the receiving side. Examples of FCS information include CRC (Cyclic Redundancy Code). In the address 3 field and address 4 field, the address of the transmission source terminal or the transmission destination terminal is set according to the type of frame. One or both of these may be omitted.

In the data field, arbitrary information to be notified to the destination device (in the case of a request frame, access point 11) is set. For example, a value indicating a data size desired for uplink transmission or a communication delay (allowable delay) value allowed by an application may be set. Further, the desired number of streams, or the number of channels and the channel number may be set. These data sizes and allowable delays are used to determine whether or not the access point 11 selects the wireless terminal 1 as a target for the current UL-MU transmission, and to determine the transmission data size allowed for the UL-MU transmission. Available. Note that notification of information such as data size and allowable delay is not essential.

When the access point 11 receives the request frame 21 from the wireless terminal 1, the access point 11 determines execution of UL-MU transmission. In preparation for UL-MU transmission, the access point 11 checks whether there is a wireless terminal having data for uplink transmission other than the wireless terminal 1 that transmitted the request frame 21. A wireless terminal (transmission candidate terminal) that inquires whether or not it has the data is selected. The access point 11 establishes a wireless link and selects one or a plurality of wireless terminals other than the wireless terminal 1 from wireless terminals corresponding to UL-MU transmission. The access point 11 can use the identifier of the selected wireless terminal as information for specifying the selected wireless terminal (transmission candidate terminal). The access point 11 sets the identifier of the selected wireless terminal in the inquiry frame 22 that inquires whether there is a data transmission request. Specifically, it is set in the terminal information field for each selected wireless terminal in the inquiry frame 22. The total number of radio terminals and radio terminals 1 to be selected may be the same value as the maximum multiplexable number or desired multiplex number of UL-MU transmission, or may be larger or smaller.

The wireless terminal to be selected may be determined by an arbitrary method. The selection method may be a round robin method or a random selection method. Or, select a wireless terminal having data that is predicted to be the same or close in size as the wireless terminal 1 (for example, a wireless terminal that has transmitted data having the same or close size as the wireless terminal 1 within a period retroactive from the current time). Or a method of selecting a wireless terminal having the same or close data generation cycle as that of the wireless terminal 1. Alternatively, when the channel response with each wireless terminal is grasped in advance, a combination of wireless terminals having a small spatial correlation (small interference) may be selected.

Here, the inquiry frame 22 will be described in more detail. The inquiry frame 22 may be defined based on the general MAC frame format shown in FIG. 4 in the same manner as the request frame. The frame control field type may be a value representing a control frame, and the subtype value may be a newly defined value for the inquiry frame. However, a configuration in which the frame type of the inquiry frame is not a control frame but a management frame or a data frame is not excluded. The receiving address may be a broadcast address or a multicast address and set in the address 1 field. The source address may be the address of the access point 11 and set in the address 2 field. The data field is provided with a terminal information field for each selected wireless terminal (transmission candidate terminal), and the identifier of the selected wireless terminal is set in the corresponding terminal information field.

FIG. 5 shows an example of a terminal information field for each wireless terminal. From the terminal information field 1 (STA info 1) to the terminal information field n (STA info n), n terminal information fields are indicated. The number of terminal information fields may be the same as the selected number of terminals. The identifier of the wireless terminal may be the MAC address of the wireless terminal, an association ID (AID) assigned by the access point 11 at the time of association, or any other ID unique among the terminals. Further, if there is information to be individually notified to the selected wireless terminal, the information may be set in the terminal information field.

Here, when selecting a plurality of wireless terminals, the access point 11 sets the identifier of the wireless terminal that transmits the request frame in the terminal information field at a predetermined position as a response to the inquiry frame 22. As an example, it is set in the head terminal information field (STA info 1). In the following, the description will be continued assuming this. For the wireless terminal set in the terminal information field other than the head, the request frame is transmitted as a response to the polling frame by transmitting the polling frame in order after the inquiry frame 22 is transmitted. For a wireless terminal whose identifier is set in the first terminal information field (hereinafter referred to as the first wireless terminal), a request frame is transmitted as a response to the inquiry frame 22 so that an inquiry by a polling frame can be made unnecessary. Can be shortened accordingly. In addition, when a period during which reception of a request frame can be accepted (request frame recruitment period) is determined, the possibility of reliably transmitting the request frame can be increased for the leading wireless terminal. In other words, the end wireless terminal may not be given an opportunity to transmit the request frame after the recruitment period ends in the middle of request frame collection processing (for example, the first wireless terminal or the subsequent wireless terminal For example, when the wireless terminal repeatedly resends the request frame).

The access point 11 transmits an inquiry frame 22 having the above-described format after SIFS from the completion of reception of the request frame 21. The wireless terminal that has received the inquiry frame 22 transmitted from the access point 11 confirms whether its own apparatus is specified in the head terminal information field. When the own terminal is specified in the head terminal information field, a request frame is generated and transmitted to the access point 11 after SIFS from completion of reception of the inquiry frame 22 (first operation). If it is not specified in the first terminal information field, check whether it is specified in one of the other terminal information fields. If the local device is specified in one of the other terminal information fields, then The reception of the polling frame transmitted from the access point 11 is awaited. In this case, as will be described later, when receiving the polling frame from the access point 11, the wireless terminal transmits a request frame (second operation). As described above, the wireless terminal selects the first operation or the second operation based on the inquiry frame 22, and executes the selected operation. If it is specified in a field other than the first terminal information field, check the number of the first terminal information field from the first terminal information field (that is, the priority of the own device) and check the priority. In response to this, a time until transmission of a polling frame transmitted from the access point 11 is calculated may be calculated, and during that time, a transition may be made to a low power consumption state such as a power save mode. In this case, it is assumed that the access point 11 sequentially transmits polling frames from the wireless terminal specified in the next terminal information field at the head, and the lengths of the polling frame and the request frame are fixed. Therefore, the wireless terminal can calculate the earliest timing at which the polling frame is transmitted to its own device.

In the example of FIG. 3, the wireless terminal 2 is specified in the terminal information field 1 at the head of the inquiry frame 22, and the wireless terminal 2 notifies the presence / absence of a data transmission request after SIFS from completion of reception of the inquiry frame 22. The request frame 23 is transmitted to the access point 11. That is, the wireless terminal 2 performs a first operation of transmitting a request frame after SIFS from completion of reception of the inquiry frame 22.

The format of the request frame 23 may be the same as or different from the format of the request frame 21 (trigger request frame). For example, a field indicating whether or not there is data for uplink transmission (transmission data presence / absence field) may be added to the format of the request frame 21. When there is data for uplink transmission, a bit is set in the transmission data presence / absence field, and when there is no such data, the bit of the transmission data presence / absence field is turned off. The access point 11 that has received the request frame 23 checks whether a bit is set in the field, and only when the bit is set, the data size field, the allowable delay field, and the like (if these fields exist) You may make it confirm. Alternatively, if there is no transmission data presence / absence field in the format of the request frame and there is no data for uplink transmission, the data for uplink transmission exists by setting the value of the data size field to 0 It may be notified to the access point 11 that it will not. Note that a transmission data presence / absence field may also exist in the trigger request frame (request frame 21).

The

wireless terminals

3 and 4 confirm that their own identifiers are not specified in the first terminal information field 1 of the inquiry frame 22 and are specified in the second and third terminal information fields 2 and 3, respectively. To do.

The access point 11 that has received the request frame 23 from the wireless terminal 2 analyzes the request frame 23 and grasps that the wireless terminal 2 has data for uplink transmission. In addition, according to the frame format of the request frame 23, the data size or allowable delay is also grasped. The access point 11 transmits a polling frame 24 instructing transmission of a request frame to the wireless terminal 3 specified in the second terminal information field 2 after SIFS from completion of reception of the request frame 23.

As with the request frames 21 and 23 and the inquiry frame 22, the polling frame 24 may be defined based on the general MAC frame format shown in FIG. The frame control field type may be a value representing a control frame, and the subtype value may be a newly defined value for a polling frame. However, the configuration in which the frame type of the polling frame is not a control frame but a management frame or a data frame is not excluded. The reception destination address may be the MAC address of the polling frame transmission destination (in this example, the wireless terminal 3) and may be set in the address 1 field. The source address may be the address of the access point 11 and set in the address 2 field. In the data field, the identifier of the wireless terminal 3 may be set to explicitly notify that the wireless terminal 3 is designated, or the receiving address of the polling frame 24 is the wireless terminal 3. Since it is understood that the wireless terminal 3 is designated, the data field itself can be omitted.

The wireless terminal 3 that has received the polling frame 24 transmits a request frame 25 after SIFS from completion of reception. That is, the wireless terminal 3 performs a second operation of transmitting a request frame after SIFS from completion of reception of the polling frame. Details of the request frame 25 are the same as those of the request frame 23, and thus the description thereof is omitted.

The access point 11 that has received the request frame 25 from the wireless terminal 3 analyzes the request frame 25 and grasps that the wireless terminal 3 has data for uplink transmission. In addition, according to the frame format of the request frame 25, the data size or allowable delay is also grasped. Next, the access point 11 transmits a polling frame 26 instructing transmission of a request frame to the wireless terminal 4 specified in the third terminal information field 3 in the same manner as in the wireless terminal 3.

The wireless terminal 4 that has received the polling frame 26 transmits a request frame 27 after SIFS from completion of reception. That is, the wireless terminal 4 performs a second operation of transmitting a request frame after SIFS from the completion of polling frame reception. The details of the request frame 27 are the same as those of the request frames 23 and 25, and thus description thereof is omitted.

The access point 11 that has received the request frame 27 from the wireless terminal 4 analyzes the request frame 27 and grasps that the wireless terminal 4 has data for uplink transmission. Further, the data size or allowable delay is also grasped according to the frame format of the request frame 27.

When the predetermined condition is satisfied, the access point 11 ends the recruitment period and stops receiving the request frame. The access point 11 selects a wireless terminal that is a target device that is permitted to transmit UL-MU, and transmits a notification frame 28 that designates the selected wireless terminal that is a trigger for starting UL-MU transmission.

As a predetermined condition, there is a case where a predetermined time (time limit) has been reached after the transmission of the inquiry frame 21 is completed. Alternatively, there may be a case where one of the time set in advance and the completion of reception of request frames from all of the wireless terminals specified by the inquiry frame 22 is established. Alternatively, the wireless terminal that has notified the request frame that it has data for uplink transmission may match a predetermined value including the trigger terminal. The example described here is an example, and other conditions may be used.

Here, regarding the time limit, a field for storing the time limit (Time Limit) may be prepared in the inquiry frame 22, and the time limit of the recruitment period may be notified in this field. Even if there is data for uplink transmission, the wireless terminal specified by the inquiry frame does not receive the polling frame at the timing when reception at the access point 11 is in time by the time limit (or when the time limit elapses) May determine that the own device does not participate in the current UL-MU transmission, and release the waiting for polling frame reception.

In the example of FIG. 3, since the access point 11 has received the request frames 23, 25, and 27 from all of the wireless terminals specified by the inquiry frame 22, the recruitment period ends. The access point 11 may select all the wireless terminals (including the trigger terminal) that transmitted the request frame as long as the wireless terminal is allowed to transmit UL-MU as long as it is below the maximum value that can be multiplexed. However, the wireless terminals that are allowed to transmit UL-MU may be narrowed down according to an arbitrary standard. For example, the wireless terminal with the largest transmission data size may be preferentially selected, or the wireless terminal having data with a high degree of urgency may be preferentially selected. In the latter case, it is assumed that the urgency of data or the type of data is also notified in the request frame.

After completing the recruitment period, the access point 11 performs carrier sense according to CSAM / CA access control to acquire a transmission right, and transmits a UL-MU transmission during TXOP (Transmission Opportunity). A notification frame 28 serving as a trigger is transmitted. Here, the reception period ends when reception of the request frame 27 is completed, carrier sense is performed from that point, a transmission right is acquired, and a notification frame 28 is generated. Alternatively, the access point 11 may transmit the notification frame 28 after SIFS from the completion of reception of the last received request frame 27.

Here, the notification frame 28 may be defined on the basis of the general MAC frame format shown in FIG. 4 in the same manner as the request frame, the inquiry frame, and the polling frame. The frame control field type may be a value representing a control frame, and the subtype value may be a newly defined value for the notification frame. However, a configuration in which the frame type of the notification frame is not a control frame but a management frame or a data frame is not excluded. The receiving address may be a broadcast address or a multicast address and set in the address 1 field. The source address may be the address of the access point 11 and set in the address 2 field. In the data field, terminal information fields corresponding to the number of terminals permitted to transmit UL-MU are set as shown in FIG. 5 in the same manner as the inquiry frame. In the example of FIG. 3, four terminal information fields 1 to 4 are set in order to allow the wireless terminals 1 to 4 to transmit UL-MU. In each terminal information field, information such as identifiers of wireless terminals permitted to transmit, and parameter information for transmission is set as necessary.

The identifier of the wireless terminal set in the terminal information field may be the MAC address of the terminal, an association ID (AID), or other ID that is unique among terminals. In the terminal information field, information individually notified to the wireless terminal, such as parameter information used by the wireless terminal at the time of UL-MU transmission, may be set. Examples of parameter information include at least one of a data length that permits transmission, a period during which transmission is permitted, an error correction code scheme, and an MCS (Modulation and Coding Scheme) that defines a transmission rate.

Further, in the case of UL-MU-MC transmission, information on one or a plurality of channels assigned to the corresponding wireless terminal may be notified as parameter information. The channel information may be specified by a channel number, for example. When a plurality of channels are allocated, the number of channels from a specific channel to the high frequency side or the low frequency side or how many frequency bands from the specific channel may be specified. In the case of resource-unit-based UL-OFDMA, information on resource units to be allocated to wireless terminals may be reported as parameter information instead of channel information or together with channel information.

In the case of UL-MU-MIMO transmission, information on the pattern of a preamble (preamble for estimating a channel response) to be added to the head of a data frame transmitted by UL-MU may be notified as parameter information. At this time, it is assumed that the access points are selected so that the preamble patterns are orthogonal to each other between transmission-permitted wireless terminals (details will be described later). In the case of UL-MU-MIMO transmission, the notification frame 28 may notify the number of streams permitted to be transmitted to the wireless terminal. It is assumed that the number of streams that can be supported by the wireless terminal has already been acquired as capability information of the terminal.

Note that, in addition to the terminal information field, the notification frame 28 may be provided with a common information field for notifying common information (Common Information) between wireless terminals permitted to transmit. In the common information field, information that is commonly notified to a group of terminals permitted to transmit is set. For example, the transmission data size permitted for each wireless terminal, the type of transmission data permitted for each wireless terminal, the format of the terminal information field, and the like may be set as common values in this field.

The wireless terminals 1 to 4 that have received the notification frame 28 from the access point 11 and have been permitted to perform uplink transmission in the notification frame 28, receive a data frame including data for uplink transmission after SIFS from completion of reception of the notification frame 28. 29, 30, 31, and 32 are transmitted to the access point 11. As a result, the access point 11 simultaneously receives signals transmitted from the wireless terminals 1 to 4. That is, the transmission timings of the data frames transmitted by the wireless terminals 1 to 4 are synchronized with each other, and are transmitted from the wireless terminals 1 to 4 by frequency multiplexing or spatial multiplexing (that is, channel-based or resource unit-based OFDMA or UL-MU). -MIMO transmission). If the data transmitted by the wireless terminal in UL-MU is less than the data size specified in the terminal information field or common information field, insufficient padding data may be added, which corresponds to the shortage. During this time, no transmission operation may be performed.

As described above, for the purpose of estimating the propagation path response on the head side of the data frame transmitted by each

wireless terminal

1, 2, 3, 4 that is permitted to perform uplink transmission of UL-MU-MIMO. More specifically, a preamble having a pattern orthogonal to each other between these wireless terminals may be added. As a method for orthogonalizing preambles between terminals, any of temporal, frequency, and coding methods can be used. In the case of time orthogonality, the preamble field is divided into a plurality of sections, and the preamble of each terminal is transmitted in a different section. In any section, only one terminal transmits the preamble. That is, while a certain terminal transmits a preamble, there is a period during which no other terminal transmits anything. In the case of frequency orthogonality, each terminal transmits a preamble signal at a frequency that is orthogonal to each other. In the case of code orthogonality, each terminal transmits a signal in which value strings (more specifically, symbol strings corresponding to the value strings) included in different rows (or different columns) of the orthogonal matrix are arranged. Each row (or each column) of the orthogonal matrix is orthogonal to each other. In any orthogonal method, the access point 11 can identify the preamble of each terminal.

In order for each terminal to use a preamble that is orthogonal to each other, the access point needs to give information on the preamble used by each terminal and its transmission method. Specifically, in the case of time orthogonality, Transmit the preamble (preamble may be the same or different between terminals) at the timing, or in the case of frequency orthogonal, at which frequency the preamble (preamble signal may be the same between terminals or different In the case of code orthogonality, information on which coding pattern (which row or column pattern of the orthogonal matrix) is used to transmit the preamble is required.

Fig. 6 shows an example of a physical packet format. Fields (L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-STF, VHT-SIG-B) corresponding to the physical header and fields for setting MAC frames (here, data frames) ( DATA field). L-STF, L-LTF, L-SIG, and VHT-SIG-A are the same in all wireless terminals. L-SIG and VHT-SIG-A can be demodulated using L-LTF symbols. L-SIG describes the data length, modulation method, and the like.

VHT-SIG-A describes information of terminals 1 to 4 such as the number of streams of each of wireless terminals 1 to 4 and the coding (error correction code such as BCC or LDPC) method. Since L-SIG and VHT-SIG-A cannot be spatially separated between terminals, the values of L-SIG and VHT-SIG-A of each wireless terminal must be the same. For this reason, the access point 11 notifies the number of streams and the coding method of each wireless terminal in a notification frame, and each wireless terminal uses the same information of other wireless terminals and uses the same VHT-SIG-A symbol. Generate with content. A value that can be set in L-SIG may be determined in advance by the system, or may be notified by a notification frame if necessary.

Also, the VHT-STF symbols are the same in the wireless terminals 1 to 4, but the VHT-LTF needs to have preamble patterns orthogonal to each other in the wireless terminals 1 to 4 in order to spatially separate subsequent fields. There is. Therefore, in the terminal information fields 1 to 4 in the notification frame, preamble patterns that are orthogonal to each other are designated by the wireless terminals 1 to 4.

In the case of UL-OFDMA, each user (wireless terminal) is assigned to a different channel or resource unit, that is, is orthogonal in frequency, and therefore the VHT-LTF preamble pattern need not be orthogonal. Therefore, a preamble pattern common to each wireless terminal may be specified in the common information field of the notification frame or the like, and a preamble pattern arbitrarily determined for each wireless terminal is specified in each terminal information field of the notification frame. May be. Alternatively, the access point may notify the wireless terminal of the preamble pattern with an arbitrary management frame when establishing a wireless link with the wireless terminal. In addition, the value of VHT-SIG-A does not need to be aligned with other wireless terminals, and only the value of the own device need be described.

Using the VHT-LTF preamble, the access point 11 acquires uplink propagation path information between each antenna of each of the wireless terminals 1 to 4 and the access point 11 antenna, and uses this propagation path information. Thus, the VHT-SIG-B and the MAC frame portion (DATA field) after the preamble can be demodulated. In VHT-SIG-B, MCS (Modulation and Coding Scheme) is set.

As described above, when the access point 11 receives signals transmitted from the radio terminals 1 to 4 in the uplink, the access point 11 performs signal reception processing according to the UL-MU method to be used, and further performs physical layer processing such as demodulation. To obtain a data frame of each wireless terminal. Then, for each data frame, based on the FCS information, whether or not the data frame has been normally received is inspected, and confirmation response information indicating a result of whether or not the data frame has been normally received is generated. The access point 11 generates a BlockACK frame 33 including the confirmation response information of each wireless terminal, and transmits the generated BlockACK frame 33 to the wireless terminals 1 to 4 that transmitted the data frame by UL-MU.

The wireless terminals 1 to 4 detect their own acknowledgment response information from the BlockACK frame received from the access point 11 and grasp whether or not the data frame has been successfully transmitted. Here, the Block ACK frame is transmitted as a response to the UL-MU transmission from the access point 11, but instead of transmitting the Block ACK frame, an ACK frame may be individually returned to the wireless terminal that has successfully received the data frame. . An ACK frame is not returned to the wireless terminal that has not successfully received the data frame. The terminal that has received the ACK frame determines that transmission of the data frame has succeeded, and the terminal that has not received the ACK frame determines that transmission of the data frame has failed. Alternatively, the access point 11 can also transmit an aggregation frame (which may be called a super frame) in which a plurality of frames including the inspection result of each wireless terminal are aggregated.

FIG. 7 is a functional block diagram of the wireless communication device mounted on the access point 11. As described above, the access point 11 may be connected to a network other than the network on the wireless terminals 1 to 4 side. FIG. 7 shows a device configuration connected to the networks on the wireless terminals 1 to 4 side.

7 includes a control unit 101, a transmission unit 102, a reception unit 103,

antennas

12A, 12B, 12C, and 12D, and a buffer 104. The control unit 101 corresponds to a control unit or a baseband integrated circuit that controls communication with a wireless terminal, and the transmission unit 102 and the reception unit 103 are, for example, a wireless communication unit or an RF integrated unit that transmits and receives a frame via an antenna. Form a circuit. All or part of the processing of the control unit 101 and the processing of the digital area of the transmission unit 102 and the reception unit 103 may be performed by software (program) that operates on a processor such as a CPU, or by hardware. It may be performed by both of these software and hardware. The access point may include a processor that performs processing of all or part of the control unit 101, the transmission unit 102, and the reception unit 103.

The buffer 104 is a storage unit for transferring data frames between the upper layer and the control unit 101. The upper layer stores a frame received from another network (for example, data stored in the payload portion of the MAC frame) in the buffer 104 for relaying to the network on the wireless terminal side or received from the network on the wireless terminal side The frame data is received from the control unit 101 and transferred to the upper layer. The upper layer may perform communication processing higher than the MAC layer, such as TCP / IP and UDP / IP. Further, the upper layer may perform processing of an application layer that processes data. The upper layer operation 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.

The control unit 101 mainly performs processing of the MAC layer. The control unit 101 manages access to the wireless channel and controls frame transmission at a desired timing. The control unit 101 controls communication with each wireless terminal by transmitting and receiving frames via the transmission unit 102 and the reception unit 103. Further, the control unit 101 may perform control so as to periodically transmit a beacon frame. The control unit 101 may include a clock generation unit that generates a clock. The control unit 101 may be configured to receive a clock from the outside. The control unit 101 may manage the internal time using a clock generated by the clock generation unit or a clock input from the outside. The control unit 101 may output the clock generated by the clock generation unit to the outside of the host CPU or the like.

The control unit 101 receives an association request from a wireless terminal and establishes a wireless link with the wireless terminal through a process such as authentication as necessary. The control unit 101 manages information regarding a wireless terminal that has established a wireless link, using an internal or external accessible storage device.

When the control unit 101 receives a request frame from an arbitrary wireless terminal connected to the access point, it determines execution of UL-MU transmission. Here, whether to execute UL-OFDMA (UL-MU-MC, etc.) or UL-MU-MIMO may be determined in advance as a system, and if the access point can support both types Alternatively, an identifier (method identifier) indicating which method is desired may be set in the request frame, and the control unit 101 may determine based on the method identifier in the request frame. Alternatively, which method is used may be determined by the access point autonomously and notified within the notification frame. For example, UL-OFDMA (UL-MU-MC or the like) may be determined when the number of usable channels is large, and UL-MU-MIMO or the like may be determined when the number is small. Here, it is assumed that which method is to be performed as a system is determined in advance.

When determining that UL-MU transmission is to be performed, the control unit 101 performs uplink transmission from a wireless terminal connected to the access point 11 other than the wireless terminal (trigger terminal) that transmitted the request frame. A wireless terminal (transmission terminal candidate) that inquires about whether it has data is selected. The control unit 101 sets an identifier or the like of the selected wireless terminal in each terminal information field and sets other fields (address field or the like) to generate an inquiry frame.

The control unit 101 transmits the generated inquiry frame from the transmission unit 102 after SIFS from completion of reception of the request frame. Alternatively, the carrier sense may be performed during the back-off time determined using DIFS and the subsequent random number, and if the transmission right can be acquired, the inquiry frame may be transmitted from the transmission unit 102 during TXOP.

The transmission unit 102 performs desired physical layer processing such as addition of a physical header and modulation processing on the frame input from the control unit 101. Further, DA conversion, filter processing for extracting a signal component of a desired band, and frequency conversion are performed on the frame after processing in the physical layer. The transmission unit 102 amplifies the frequency-converted signal and radiates it as a radio wave from one antenna or a plurality of antennas. In the illustrated example, one transmission unit is provided, but a plurality of transmission units may be provided, and one antenna may be connected to each transmission unit.

In addition, the control unit 101 manages carrier sense information via the receiving unit 103. Specifically, both the physical carrier sense information regarding busy and idle of the medium (CCA) input from the receiving unit 103 and the virtual carrier sense information based on the medium reservation time described in the received frame May be included. If any one of the carrier sense information indicates busy, the medium is regarded as busy, and signal transmission during that time is prohibited.

The signal received by each antenna is amplified in the receiving unit 103, subjected to frequency conversion (down-conversion), and filtered. The filtered signal is further converted into a digital signal by AD conversion, and a frame is input to the control unit 201 through physical layer processing such as demodulation. The control unit 201 analyzes the frame and performs an operation according to the analysis result. In the case of a normal frame (such as a request frame) that is not UL-MU-MIMO transmission, a signal received by any one of a plurality of antennas (any antenna or a predetermined antenna) is processed. Alternatively, a frame may be obtained by processing a signal received by each antenna using a diversity technique. Alternatively, the received signal may be processed by other methods.

When the control unit 101 receives a request frame from the wireless terminal specified in the terminal information field at the head of the inquiry frame, the control unit 101 analyzes the request frame, determines whether there is data for uplink transmission for the wireless terminal, and other requests. Information such as data size and allowable delay is grasped according to the frame format. The control unit 101 transmits a polling frame to the wireless terminal specified in the second terminal information field, and receives and analyzes the request frame as a response. Thereafter, similarly, a polling frame is transmitted and a request frame is received and analyzed up to the wireless terminal specified in the terminal information field at the end. A time limit may be set in advance. In this case, when the time limit is reached, the collection of request frames is terminated.

The control unit 101 selects a wireless terminal that performs UL-MU transmission from the trigger terminal and the wireless terminal that transmitted the request frame to the polling frame. The control unit 101 generates a notification frame in which the identifier of the selected wireless terminal and the parameter information for UL-MU transmission are set in the terminal information field, and transmits the generated notification frame.

When UL-MU-MIMO transmission is performed as UL-MU transmission, a signal transmitted by UL-MU-MIMO is received by the receiving unit 103, and MIMO demodulation is performed based on propagation path information with each wireless terminal. By doing so, it is separated into data frames for each wireless terminal. The separated data frame is sent to the control unit 101. In the illustrated example, one receiving unit is provided, but a plurality of receiving units may be arranged, and one antenna may be commonly connected to the corresponding transmitting unit for each receiving unit.

When performing UL-OFDAMU (channel-based UL-OFDM (MU-MC) or resource unit-based UL-OFDMA) as UL-MU transmission, the received signal is received by the receiving unit 103 and received. A data frame for each wireless terminal is obtained by extracting a channel component for each wireless terminal or a signal component of a resource unit for each wireless terminal from the signal and performing physical layer processing including processing such as demodulation. The acquired data frame is sent to the control unit 101. The control unit 101 has a function of controlling each band of the transmission filter and the reception filter in the transmission unit 102 and the reception unit 103.

Note that the control unit 101 may read information by accessing a storage device that stores information notified to each wireless terminal, information notified from each wireless terminal, or both. The storage device may be an internal memory or an external memory, and may be a volatile memory or a nonvolatile memory. In addition to the memory, the storage device may be an SSD, a hard disk, or the like.

The above-described separation of the processing of the control unit 101 and the transmission unit 102 is an example, and a mode different from the above-described mode is possible. For example, processing up to the digital domain and DA conversion may be performed by the control unit 101, and processing after DA conversion may be performed by the transmission unit 102. Similarly, the processing between the control unit 101 and the reception unit 103 is performed by the reception unit 103 before the AD conversion, and the control unit 101 performs the processing of the digital area including the processing after the AD conversion. May be. As an example, the baseband integrated circuit according to the present embodiment includes a control unit 101, a part that performs physical layer processing in the transmission unit 102, a part that performs DA conversion, and a part that performs processing after AD conversion in the reception unit 103. The RF integrated circuit corresponds to a part that performs processing after DA conversion in the transmission unit 102 and a part that performs processing before AD conversion in the reception unit 103. The integrated circuit for wireless communication according to this embodiment includes at least a baseband integrated circuit among a baseband integrated circuit and an RF integrated circuit. Processing between blocks or processing between the baseband integrated circuit and the RF integrated circuit may be separated by a method other than that described here.

FIG. 8 is a functional block diagram of a wireless communication device mounted on the wireless terminal 1. The wireless communication devices mounted on the wireless terminals 2 to 4 have the same configuration as that of the wireless terminal 1, and thus the description thereof is omitted.

8 includes a control unit 201, a transmission unit 202, a reception unit 203, an antenna 1A, and a buffer 204. The control unit 201 corresponds to a control unit or a baseband integrated circuit that controls communication with the access point 11, and the transmission unit 202 and the reception unit 203 form, as an example, a wireless communication unit or an RF integrated circuit that transmits and receives frames. To do. All or part of the processing of the control unit 201 and the processing of the digital area of the transmission unit 202 and the reception unit 203 may be performed by software (program) that operates on a processor such as a CPU, or by hardware. It may be performed by both of these software and hardware. The terminal may include a processor that performs processing of all or part of the control unit 201, the transmission unit 202, and the reception unit 203.

The buffer 204 is a storage unit for transferring data between the upper layer and the control unit 201. The upper layer generates data to be transmitted to another wireless terminal, the access point 11, or a device on another network, and stores the data in the buffer 204 or receives frame data received from the network on the wireless terminal side as a buffer. Or via 201. The upper layer may perform communication processing above the MAC layer such as TCP / IP and UDP / IP, and may further perform processing of an application layer that processes data. The upper layer processing 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.

The control unit 201 mainly performs MAC layer processing. The control unit 201 controls communication with the access point 11 by transmitting and receiving frames to and from the access point 11 via the transmission unit 202 and the reception unit 203. The control unit 201 receives a beacon frame periodically transmitted from the access point 11, for example, via the antenna 1A and the reception unit 203. The control unit 201 may include a clock generation unit. The control unit 201 may be configured to receive a clock from the outside. The control unit 201 may manage the internal time by the clock. The clock generated by the clock generation unit may be output to the outside.

As an example, the control unit 201 receives a beacon frame, makes an association request to the access point 11, and establishes a wireless link with the access point 11 through a process such as authentication as necessary.

When the data for uplink transmission occurs, the control unit 201 generates a request frame (trigger request frame) for UL-MU transmission and transmits it to the access point. In order to transmit a request frame, first, carrier sense is performed during DIFS and a randomly determined backoff time, a transmission right is acquired according to the carrier sense result, and a request frame is transmitted during TXOP. The request frame may include information such as the identifier of the own device, the data size, and the allowable delay in the data field.

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

The signal received by the antenna 1A is processed by the receiving unit 203. For example, a signal such as an inquiry frame, a polling frame, or a notification frame is received from the access point 11 and processed by the receiving unit 203. That is, the received signal is amplified by the receiving unit 203, subjected to frequency conversion (down-conversion), and a desired band component is extracted by the filering process. The extracted signal is further subjected to physical layer processing including AD conversion and demodulation, and a frame is input to the control unit 201. The control unit 201 analyzes the input frame and performs an operation according to the analysis result.

For example, when the control unit 201 receives an inquiry frame from the access point 11, it checks whether the identifier of the own device is set in the head terminal information field. When the identifier of the own device is set in the first terminal information field, the request frame is generated by checking the presence / absence of data for uplink transmission, the data size, etc. based on the state of the buffer 204. The control unit 201 transmits the generated request frame after SIFS from the completion of reception of the inquiry frame. If the identifier of the own device is not set in the first terminal information field, it is checked whether the identifier of the own device is set in the second and subsequent terminal information fields, and if the identifier of the own device is set Wait for polling frame reception.

When the control unit 201 receives a polling frame from the access point 11, the control unit 201 checks the presence / absence of data for uplink transmission, the data size, and the like based on the state of the buffer 205, and generates a request frame. The control unit 201 transmits the generated request frame after SIFS from the completion of reception of the inquiry frame.

Further, when the control unit 201 receives the notification frame from the access point 11, it checks whether or not the own device is designated as a UL-MU transmission target terminal. Specifically, it is confirmed whether the identifier of the own device is set in any of the terminal information fields, and if it is set, the own device is designated as a target terminal for UL-MU transmission. Judge that In this case, data is read from the buffer 204, a data frame is constructed, and the data frame is transmitted via the transmission unit 202 and the antenna 1A. At this time, the control unit 201 determines the data size or time length to be transmitted based on the parameter information specified in the terminal information field of the notification frame, and sends parameter information necessary for transmission processing to the transmission unit 202. Is specified. The transmission unit 202 performs physical layer processing using the specified parameter information. The control unit 201 transmits a data frame after a predetermined time such as SIFS from the completion of reception of the notification frame, whereby the data frame is transmitted at the same timing as other wireless terminals specified in the notification frame (UL -MU transmission). The control unit 201 has a function of controlling each band of the transmission filter and the reception filter in the transmission unit 202 and the reception unit 203.

The control unit 201 may read information by accessing a storage device for storing information notified to the access point 11, information notified from the access point 11, or both. The storage device may be an internal memory or an external memory, and may be a volatile memory or a nonvolatile memory. In addition to the memory, the storage device may be an SSD, a hard disk, or the like.

The above-described separation of the processing of the control unit 201 and the transmission unit 202 is an example, and a mode different from the above-described mode is possible. For example, processing up to the digital domain and DA conversion may be performed by the control unit 201, and processing after DA conversion may be performed by the transmission unit 202. Similarly, the processing of the control unit 201 and the reception unit 203 is performed by the reception unit 203 performing processing before AD conversion, and the control unit 201 performs processing of the digital area including processing after AD conversion. Also good. As an example, the baseband integrated circuit according to this embodiment includes a control unit 201, a part that performs physical layer processing in the transmission unit 202, a part that performs DA conversion, and a part that performs processing after AD conversion in the reception unit 203. The RF integrated circuit corresponds to a part that performs processing after DA conversion in the transmission unit 202 and a part that performs processing before AD conversion in the reception unit 203. The integrated circuit for wireless communication according to this embodiment includes at least a baseband integrated circuit among a baseband integrated circuit and an RF integrated circuit. Processing between blocks or processing between the baseband integrated circuit and the RF integrated circuit may be separated by a method other than that described here.

FIG. 9 is a flowchart of an operation example of the access point according to the first embodiment.

When the access point 11 receives a request frame from an arbitrary wireless terminal (trigger terminal) connected to the access point, the access point 11 determines to execute UL-MU transmission (S101). The access point 11 selects a wireless terminal (transmission terminal candidate) that inquires whether it has data for uplink transmission from among the connected wireless terminals that support UL-MU transmission and that have data for uplink transmission. . Then, an inquiry frame is generated by setting the identifier or the like of the selected wireless terminal in each terminal information field (S102). The access point 11 transmits the generated inquiry frame after SIFS from the completion of receiving the request frame (S102).

The access point waits for a request frame from the wireless terminal specified in the terminal information field at the head of the inquiry frame, and receives and analyzes the request frame (S103). The access point transmits a polling frame to the wireless terminal specified in the second terminal information field, and receives and analyzes a request frame from the wireless terminal. Similarly, for the wireless terminals specified in the third and subsequent terminal information fields, transmission of polling frames and reception and analysis of request frames are sequentially performed (S104). Note that the recruitment period may be ended when a predetermined condition is satisfied midway, for example, when a certain period of time has elapsed after completion of transmission of the inquiry frame. That is, the request frame collection process (transmitting a polling frame and receiving a request frame as a response thereto) may be aborted.

The access point 11 selects the UL-MU transmission target terminal (target apparatus) from the trigger terminal and the wireless terminal that has transmitted the request frame to the polling frame (S105). The access point 11 generates a notification frame in which the identifier of the selected wireless terminal and the parameter information for UL-MU transmission are set in the terminal information field, and transmits the generated notification frame (S105). The access point 11 transmits simultaneously from each wireless terminal specified in the notification frame after completion of transmission of the notification frame (channel-based UL-OFDMA (MU-MC), resource unit-based UL-OFDMA, or UL-MU). -The received signal is subjected to physical layer processing including demodulation and the like, and a data frame of each wireless terminal is obtained (S106).

FIG. 10 is a flowchart showing an operation example of the wireless terminal according to the present embodiment. Here, an operation example in the case where the wireless terminal is not a trigger terminal but a wireless terminal specified by an inquiry frame is shown.

When the wireless terminal receives the inquiry frame from the access point 11 (S201), the wireless terminal checks whether its own device is specified in the first terminal information field, that is, whether its own identifier is set in the first terminal information field. (S202). If the own device is specified in the first terminal information field (YES), the presence / absence of data for uplink transmission, the data size, etc. are confirmed, a request frame is generated, and the SIFS is received after the reception of the inquiry frame is completed. Later, a request frame is transmitted to the access point 11 (S203).

When the own device is not specified in the first terminal information field (NO in S202), it is checked whether the own device is specified in the second and subsequent terminal information fields (S204), and the second and subsequent terminal information fields. If specified in (YES), the reception of a polling frame is awaited. When a polling frame addressed to the own apparatus is received (S205), the presence / absence of data for uplink transmission, the data size, and the like are confirmed, a request frame is generated, and the access point 11 is sent to the access point 11 after SIFS from completion of reception of the polling frame. A request frame is transmitted (S206). If the own device is not specified in the second and subsequent terminal information fields (NO in S204), it is determined that the device has been excluded from the candidates for the current UL-MU transmission, and the operation of this flow is terminated.

After transmitting the request frame in step S203 or step S206, the wireless terminal waits for the arrival of the notification frame from the access point 11 and receives the notification frame (S207). Then, the wireless terminal is designated as the UL-MU transmission target terminal. It is confirmed whether it has been done (S208). Specifically, it is confirmed whether the identifier of the own device is set in any of the terminal information fields in the notification frame. When the own device is designated (YES), the wireless terminal generates a data frame based on the parameter information designated in the terminal information field for the own device in the notification frame, and the data frame is changed to the notification frame. It transmits after a certain time such as SIFS from the completion of reception (S209). When parameter information is designated in advance from an access point, it is possible to omit notification of parameter information in a notification frame. However, in the case of UL-MU-MIMO, as described above, it is necessary to receive notification of parameter information of other wireless terminals in advance in order to generate a header of a physical packet. On the other hand, if the own device is not specified in the notification frame (NO in S208), it is determined that the device has been excluded from the target terminal of the current UL-MU transmission, and the operation of this flow is terminated.

As described above, according to the present embodiment, when the access point receives a request frame requesting permission for data transmission from the wireless terminal (trigger terminal), the access point transmits an inquiry frame specifying one or more wireless terminals other than the trigger terminal. Transmit and collect request frames from the specified wireless terminal. Then, based on the request frame received from the trigger terminal and the designated wireless terminal, scheduling of UL-MU transmission (selection of a wireless terminal that performs UL-MU transmission, parameter information for transmission (data size for performing uplink transmission) And modulation / coding schemes). As a result, at least one wireless terminal having transmission data can be secured, and the request of each wireless terminal can be taken into account, thereby enabling efficient UL-MU transmission scheduling. Further, since the request frame is transmitted as a response to the wireless terminal specified in the terminal information field at the head of the inquiry frame, the overhead can be reduced without transmitting the polling frame. . In this way, scheduling of uplink multiuser transmission can be performed efficiently with little overhead.

(Second Embodiment)
In the first embodiment, after transmitting the inquiry frame, the access point collects the request frames by sequentially transmitting the polling frames to the second and subsequent wireless terminals specified by the inquiry frame. Here, a mode in which a request frame is acquired without performing the above is shown.

FIG. 11 shows an example of an operation sequence according to the second embodiment. As can be understood from the comparison with FIG. 3, the access point 11 does not transmit the polling frame after transmitting the inquiry frame 22A. Each wireless terminal (

wireless terminals

2, 3, 4 in the figure) designated by the inquiry frame 22A waits for the time designated by the inquiry frame 22A from the completion of reception of the inquiry frame 22A, respectively, and then receives the

request frame

23, 24 and 27 are transmitted.

The access point 11 instructs the wireless terminal 2 the timing after SIFS from the completion of reception of the inquiry frame 22A as the transmission timing of the request frame 23. The wireless terminal 3 is instructed as the transmission timing of the request frame 25 after the completion of the reception of the inquiry frame 22A, after a time obtained by adding twice the SIFS and the time length of the request frame 23. For the wireless terminal 4, the transmission timing of the request frame 27 is the timing after the completion of reception of the inquiry frame 22 </ b> A after adding SIFS three times, the time length of the request frame 23, and the time length of the request frame 25. Instruct. Since the time lengths of the request frames 23, 25, and 27 are determined in advance and are the same length, the transmission timing can be designated in advance in this way.

As a specific method for specifying the transmission timing for each wireless terminal, information related to the standby time is set in the terminal information field for each wireless terminal, and each wireless terminal is specified by the information from the terminal information field of its own device. A method of waiting for a waiting time can be considered. Alternatively, the waiting time may be calculated on the terminal side according to the number of the terminal information field of the own device from the top. The time length of the request frame is fixed, and if the frame interval between the inquiry frame and the request frame and between the request frames is fixed to SIFS, the waiting time can also be calculated on the terminal side. When the bit size of the request frame is fixed, since the frame length is determined by designating the MCS to be applied to the request frame in the inquiry frame, each wireless terminal can calculate the waiting time.

The request frame transmitted by each wireless terminal may not be successfully received by the access point 11, but in this case, it may be handled that the request frame cannot be received from the wireless terminal. That is, the wireless terminal is excluded from the target terminals for the current UL-MU transmission.

As described above, according to the present embodiment, it is not necessary to transmit a polling frame after transmitting an inquiry frame. Therefore, compared to the first embodiment, from the execution decision of UL-MU transmission to the start of UL-MU transmission. The overhead can be further reduced.

(Third embodiment)
In the first or second embodiment, each wireless terminal is specified in each terminal information field in order to specify the wireless terminal to which the request frame is responded in the inquiry frame. However, as another method, the individual wireless terminal is specified. Instead of this, a method of designating a group of wireless terminals is also possible.

In this case, the access point performs grouping in advance to generate one or a plurality of groups of wireless terminals. The grouping timing may be performed, for example, every time a new association process with a wireless terminal is performed, may be performed periodically, or may be performed at other timing. At this time, the same wireless terminal may be allowed to belong to a plurality of groups. The grouping method may be arbitrary. For example, when the propagation path response with each wireless terminal is grasped in advance, wireless terminals with small spatial correlation (small interference) may be grouped into the same group. The access point may notify grouping information representing the result of grouping to each wireless terminal that is the target of grouping using a management frame defined in advance.

Fig. 12 shows an example of grouping information. In this example, the grouping information has a table format, but may have another format such as a list format. A group ID is assigned to each group, and an identifier of a wireless terminal belonging to each group is set in each row. For example, wireless terminals 1 to 3 (STA1 to STA3) belong to a group having a group ID of 1. The grouping information notified to each wireless terminal may be information regarding all groups or only information regarding the group to which each wireless terminal belongs.

When the access point decides to execute UL-MU transmission in response to the reception of the trigger request frame, the access point selects a target group from the group generated in advance. Then, the identifier (group ID) of the selected group is set in the group ID field of the inquiry frame. The terminal information field for each wireless terminal belonging to the group of the group ID may be omitted when there is no information to be notified individually to each wireless terminal. When a target group is specified, it may be allowed that the wireless terminal 1 (trigger terminal) that transmitted the first request frame 21 belongs to the specified group. In this case, the wireless terminal 1 may operate so as not to perform anything on the access point 11 even when the inquiry frame 22 in which the group ID is set is received.

In the first or second embodiment, the wireless terminal that directly responds to the inquiry frame is the wireless terminal specified in the terminal information field at the predetermined position, specifically, the head terminal information field. On the other hand, in this embodiment, a wireless terminal described at a predetermined position in the grouping information is a wireless terminal that directly responds to the inquiry frame.

For example, in the grouping information in FIG. 12, the wireless terminal described in the leftmost column of the table is a wireless terminal that responds to the inquiry frame. In other words, the priority is set so as to decrease from the left column to the right column of the table, and the wireless terminal with the highest priority responds to the inquiry frame. The wireless terminals described from the second column from the left to the right (second and subsequent priority wireless terminals) transmit a request frame according to the first or second embodiment. That is, in the case of conforming to the first embodiment, a request frame is transmitted as a response when a polling frame is received from an access point. In the case of conforming to the second embodiment, a request frame is transmitted at the timing specified in the inquiry frame, or what number is listed from the leftmost column of the own device (what is the priority) The request frame is transmitted at a timing determined according to the above. However, if the trigger terminal belongs to the specified group and the trigger terminal belongs, the identifier of the trigger terminal is set in the inquiry frame, and the wireless terminal specified in the inquiry frame (belongs to the specified group) Terminals other than the trigger terminal among the terminals may determine the priority order of their own devices except for the trigger terminal.

As another method for designating a wireless terminal that directly responds to the inquiry frame, the identifier of the wireless terminal that directly responds may be set in the inquiry frame in addition to the group ID. In this case, in addition to the group ID field, a response terminal field for setting an identifier of a wireless terminal that directly responds may be defined in the inquiry frame. FIG. 14 shows an example of the group ID field and the response terminal field. These fields can be arranged in the data field of the MAC frame shown in FIG. The access point selects a wireless terminal (excluding the trigger terminal) that directly responds from the wireless terminals belonging to the selected group, and sets the group ID of the group and the identifier of the selected wireless terminal to the group ID of the inquiry frame. Set in the field and response terminal field. If the wireless terminal that has received the inquiry frame belongs to the group set in the group ID field and is specified in the response terminal field, the wireless terminal should return a request frame after SIFS from completion of reception of the inquiry frame. That's fine. If the own device belongs to the group set in the group ID field but is not specified in the response terminal field, the request frame may be transmitted in the same manner as the second and subsequent priority wireless terminals. When the trigger terminal is allowed to belong to the specified group and the trigger terminal belongs, the above-described example may be followed.

In this way, the length of the inquiry frame can be shortened by specifying the group ID instead of specifying the identifier of each wireless terminal in the inquiry frame.

Also, the access point may specify the notification frame to be transmitted to the wireless terminal selected as the UL-MU transmission target terminal by the group ID in the same manner. In this case, the access point selects a group that permits UL-MU transmission, and sets the identifier (group ID) of the selected group in the group ID field of the notification frame. At this time, if each terminal information field is assigned in order from the left according to the priority in the group, setting of the identifier of the wireless terminal in each terminal information field is omitted, and parameters other than the identifier of the wireless terminal are set. Only information or the like may be set. Thereby, the frame length of the notification frame can be shortened. The group specified by the notification frame may be allowed to include wireless terminals that have not acquired the request frame, or the specified group may include only the wireless terminal that has acquired the request frame. A group may be selected.

(Fourth embodiment)
In the first to third embodiments, the access point acquires a request frame from each wireless terminal by central control type access control. That is, the access point controls to transmit a request frame to the target wireless terminal by transmitting an inquiry frame or a polling frame. On the other hand, this embodiment shows a mode in which each wireless terminal transmits a request frame in accordance with distributed control access control, specifically, CSMA / CA.

FIG. 14 shows an example of an operation sequence according to the fourth embodiment. The access point transmits the inquiry frame 22 as in the first or second embodiment. The wireless terminal that has received the inquiry frame 22 checks whether its own device is specified in the inquiry frame 22, and if so, transmits a request frame in accordance with CSMA / CA. When the access point normally receives the request frame received from the wireless terminal, the access point returns an ACK frame after SIFS from completion of reception. In the example of FIG. 14, the wireless terminals 2 to 4 are specified in the inquiry frame 22, the wireless terminal 2 first obtains the transmission right and transmits the request frame 23, and the access point receives it normally. ACK frame 41 is returned. Next, the wireless terminal 3 acquires the transmission right, transmits the request frame 25, and the access point normally receives it and returns the ACK frame 42. Similarly, the wireless terminal 4 transmits a request frame from the wireless terminal 4 and an ACK frame from the access point, which is not shown. Note that if the wireless terminal does not receive the ACK frame for the transmitted request frame, the wireless terminal may retransmit the request frame assuming that the transmission has failed. In the first to third embodiments, the subsequent operation changes depending on the position of the terminal information field specified in the inquiry frame 22 (particularly depending on whether it is the head or not). In this embodiment, each wireless terminal No matter what terminal information field the identifier is set, the operation is not affected.

In the operation example of FIG. 14, the access point returns an ACK frame in response to reception of the request frame, but transmission of the ACK frame may be omitted. An example of the operation sequence in this case is shown in FIG. The access point receives the request frames 23, 25, and 27 from the wireless terminals 2 to 4, but does not return an ACK frame. As a result, the reachability of the request frame transmitted by the wireless terminal cannot be guaranteed, but the recruitment period can be shortened.

Here, the access point may end the recruitment period (request frame collection processing) when a predetermined condition is satisfied. Predetermined conditions include when a predetermined time has elapsed since the completion of transmission of the inquiry frame, or when request frames have been received from all wireless terminals specified in the inquiry frame. In addition, there are times when request frames are received from a predetermined number of wireless terminals. As the predetermined number, for example, there is a value obtained by subtracting 1 from the desired multiplexing number or the maximum possible multiplexing number. The reason why 1 is subtracted is to exclude the trigger terminal. The access point selects a UL-MU transmission target terminal from the wireless terminals that transmitted the request frame, and transmits a notification frame 28 designating the selected wireless terminal.

As described above, according to the present embodiment, since the request frame is transmitted according to CSMA / CA, the load on the access point can be reduced, and the overhead until the UL-MU transmission start can be reduced.

(Fifth embodiment)
In the fourth embodiment, it is assumed that the wireless terminal specified by the inquiry frame transmits a request frame regardless of the presence / absence of uplink transmission data. That is, when there is no data for uplink transmission, it is assumed that a request frame with a data size of 0 or a transmission data presence / absence bit turned off is transmitted. The same applies to the first to third embodiments.

In the present embodiment, as in the fourth embodiment, in a system that transmits a request frame in accordance with CSMA / CA, the request frame is transmitted only when uplink transmission data is included. The access point generates and transmits an inquiry frame in the same manner as in the fourth embodiment. The wireless terminal that has received the inquiry frame confirms whether its own device is designated by the inquiry frame, and when the own device is designated and has data for uplink transmission, the wireless terminal transmits the request frame according to CSMA / CA. Send. Even if the own device is specified, if there is no data for uplink transmission, the request frame is not transmitted. As in the fourth embodiment, the access point terminates the recruitment period (request frame collection processing) when a predetermined condition is satisfied, and selects the UL-MU transmission target from the wireless terminals that transmitted the request frame. Select a terminal. The access point generates a notification frame specifying the selected wireless terminal, and transmits the generated notification frame.

As described above, according to the present embodiment, only the wireless terminal having data for uplink transmission returns the request frame in response to the inquiry frame, thereby improving the bandwidth usage efficiency and starting UL-MU transmission. Can be further reduced.

(Sixth embodiment)
In the embodiments described so far, the access point designates the wireless terminal that requests or permits transmission of the request frame in the inquiry frame, but designates all the wireless terminals that are already connected (wireless links have been established). It is also possible not to explicitly specify the wireless terminal. In this case, the terminal information field may be omitted from the inquiry frame. When there is information to be commonly notified to each wireless terminal, a common information field may be added to the inquiry frame, and information to be commonly notified to each wireless terminal may be set in the field.

An example of operation when a request frame is transmitted by distributed control type access control based on the fifth embodiment will be described. The access point generates and transmits an inquiry frame with a receiving address as a broadcast address or a multicast address. This inquiry frame may not have the terminal information field. The wireless terminal that has received the inquiry frame confirms whether it has data for uplink transmission, and if it has data for uplink transmission, returns a request frame according to CSMA / CA. When there is no data for uplink transmission, the request frame may not be returned as in the fourth embodiment, or the request frame may be returned as in the third embodiment. The access point ends the recruitment period when the predetermined condition ends after the transmission of the inquiry frame is completed. The access point selects a terminal that is a target of UL-MU transmission from the wireless terminals (including the trigger terminal) that transmitted the request frame, and generates and transmits a notification frame.

As described above, according to the present embodiment, since the terminal information field can be omitted from the inquiry frame, the frame length of the inquiry frame can be shortened.

(Seventh embodiment)
FIG. 21 shows an example of the overall configuration of a terminal (non-access point terminal) or access point. This configuration example is an example, and the present embodiment is not limited to this. The terminal or access point includes one or more antennas 1 to n (n is an integer of 1 or more), a wireless LAN module 148, and a host system 149. The wireless LAN module 148 corresponds to the wireless communication device according to the first embodiment. The wireless LAN module 148 includes a host interface, and is connected to the host system 149 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 through wiring on the substrate is also possible. The host system 149 communicates with an external device using the wireless LAN module 148 and the antennas 1 to n according to an arbitrary communication protocol. The communication protocol may include TCP / IP and higher layer protocols. Alternatively, TCP / IP may be 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. 22 shows a hardware configuration example of the wireless LAN module. This configuration can also be applied when the wireless communication apparatus is mounted on either a non-access point terminal or an access point. That is, it can be applied as an example of a specific configuration of the wireless communication apparatus illustrated in FIG. In this configuration example, there is only one antenna, but two or more antennas may be provided. In this case, a plurality of sets of a transmission system (216, 222 to 225), a reception system (232 to 235), a PLL 242, a crystal oscillator (reference signal source) 243, and a switch 245 are arranged corresponding to each antenna. May be connected to the control circuit 212, respectively.

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. Either or either of the DAC 216 and the ADC 217 may be arranged in the RF IC 221 or may be arranged in 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. The memory 213 stores information notified to the terminal or access point, information notified from the terminal or access point, or both. 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 the host system. The interface may be anything such as UART, SPI, SDIO, USB, and 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, encodes, encrypts, and modulates (may include MIMO modulation) as a physical layer process to a frame to be transmitted. For example, two types of digital baseband signals ( Hereinafter, a digital I signal and a digital Q signal) are generated.

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.

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 obtains a signal having the constant frequency by performing feedback control using the VCO based on an oscillation signal input from the crystal oscillator 243. The generated constant frequency signal is input to the mixer 223 and the mixer 233. The PLL 242 corresponds to an example of 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). The RF IC 221 handles balanced signals, but since the unbalanced signal is handled from the output of the RF IC 221 to the antenna 247, these signals are converted by the balun 225.

The switch 245 is connected to the balun 225 on the transmission side during transmission, and is connected to the low noise amplifier (LNA) 234 or RF IC 221 on the reception side during reception. The control of the switch 245 may be performed by the baseband IC 211 or the RF IC 221, or another circuit for controlling the switch 245 may exist and the switch 245 may be controlled from the circuit.

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

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 an unbalance-balance conversion on the signal amplified by the low noise amplifier (LNA) 234. A configuration in which the order of the balun 235 and the LNA 234 is reversed may be used. 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 90 ° behind the signal. 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 the digital Q signal, the baseband circuit 212 performs physical layer processing (including MIMO demodulation) such as demodulation processing, error correction code processing, and physical header processing, and obtains 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.

The details of the processing of each unit described above are self-evident from the description of FIG. 7 or FIG.

(Eighth embodiment)
18A and 18B are perspective views of wireless devices according to the eighth embodiment, respectively. The wireless device in FIG. 18A is a notebook PC 301, and the wireless device in FIG. 18B is a mobile terminal 321. Each corresponds to one form of a terminal (including an access point). 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, a wireless communication device mounted on a terminal (including an access point) described so far can be used. A wireless device equipped with a wireless communication device is not limited to a notebook PC or a mobile terminal. For example, it can be mounted on a TV, a digital camera, a wearable device, a tablet, a smartphone, and the like.

In addition, the wireless communication device mounted on the terminal (including the access point) can be mounted on the memory card. An example in which the wireless communication device is mounted on a memory card is shown in FIG. 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. In FIG. 19, description of other elements (for example, a memory) in the memory card 331 is omitted.

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

(Tenth embodiment)
In the tenth embodiment, in addition to the configuration of the wireless communication apparatus according to the above-described embodiment, a clock generation unit is provided. 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.

(Eleventh embodiment)
In the eleventh embodiment, in addition to the configuration of the wireless communication apparatus according to the above-described embodiment, 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.

(Twelfth embodiment)
In the twelfth embodiment, a SIM card is included in addition to the configuration of the wireless communication apparatus described above. The SIM card is connected to, for example, a transmission unit, a reception unit, or a control unit 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.

(13th Embodiment)
The thirteenth embodiment includes a moving image compression / decompression unit in addition to the configuration of the wireless communication apparatus according to the above-described embodiment. The moving image compression / decompression unit is connected to the bus. As described above, by providing the wireless communication device with the moving image compression / decompression unit, it is possible to easily transmit the compressed moving image and expand the received compressed moving image.

(Fourteenth embodiment)
In the fourteenth embodiment, in addition to the configuration of the wireless communication apparatus according to the above-described embodiment, an LED unit is included. The LED unit is connected to the transmission unit, the reception unit, or the control unit. 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.

(Fifteenth embodiment)
The fifteenth embodiment includes a vibrator unit in addition to the configuration of the wireless communication apparatus according to the above-described embodiment. The vibrator unit is connected to the transmission unit, the reception unit, or the control unit. 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.

(Sixteenth 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 In general, frames handled on a radio access protocol in a radio communication system are roughly classified into three types: a data frame, a management frame, and a control frame. 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 device. For example, there are a frame used for setting communication with another wireless communication device, a frame for releasing a communication link (that is, disconnecting), 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 the IEEE 802.11 standard (the aforementioned IEEE Std
(Including extended standards such as 802.11ac-2013), there is an association process as one of the procedures for establishing a connection. The association request frame and association response frame used in the process are management frames, and the association request. Since the frame and the Association Response frame are unicast management frames, the reception side wireless communication terminal is requested to transmit an ACK frame as a response frame, and the ACK frame is a control frame as described above.

[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. Then, if it is a non-access point 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 access point and a wireless communication terminal is disconnected, for example, if the wireless communication access point has a connection management table for managing a 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 an AID is assigned at the stage where the wireless communication access point has permitted connection to each wireless communication terminal that joins its own BSS in the association process, 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.

A timer is used as a specific example of determining disconnection by an implicit method. For example, when transmitting a data frame requesting a delivery confirmation response frame, a first timer (for example, a retransmission timer for a data frame) that limits 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 restarted 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 space (AIFS), point coordination function intra interface space interface (IFS). There are six types, reduced interface space (RIFS).

The definition of the frame interval is defined as a continuous period to be opened after confirming the carrier sense idle before transmission in the IEEE 802.11 wireless LAN, 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 made 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 transferred 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.

PIFS is a frame interval for enabling access with priority over other competing wireless communication devices, and has a shorter period than either of the values of DIFS and AIFS. SIFS is a frame interval that can be used when transmitting a control frame of a response system or when 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. 20 shows an example of a frame exchange during 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 (busy medium) as a result of carrier sense. In this case, the AIFS of a fixed time is vacated from the time when the carrier sense becomes idle, and then the data frame W_DATA1 is transmitted to the communication partner when the random time (random backoff) is vacant. 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 contention windows (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 from the time point. Upon receiving W_ACK1, the wireless communication apparatus that has transmitted W_DATA1 transmits the next frame (for example, W_DATA2) after SIFS from the time when the physical packet containing W_ACK1 is occupied on the wireless medium if within the transmission burst time limit. be able to.

AIFS, DIFS, PIFS, and EIFS are functions of SIFS and slot time, and SIFS and slot time are defined for each physical layer. Parameters for which values are provided for each access category, such as AIFS, CWmin, and CWmax, can be set for each communication group (Basic Service Set (BSS) in the IEEE 802.11 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. In a wireless communication apparatus capable of efficiently taking EIFS, the occupation time length of a physical packet carrying a response frame to a physical packet that has activated EIFS is estimated, and the sum of SIFS, DIFS, and the estimated time may be used. it can. In the present embodiment, a wireless communication system using such a frame interval parameter is assumed as an interference system having a wide communication range.

It should be noted that the frame described in each embodiment may refer to what is called a packet in the IEEE 802.11 standard or a compliant standard such as Null Data Packet.

Note that frames transmitted by a plurality of terminals may have different contents or the same contents. As a general expression, when it is expressed that a plurality of terminals transmit or receive the Xth frame, the contents of these Xth frames may be the same or different. X is an arbitrary value. Similarly, when it is expressed that the terminal transmits a plurality of Xth frames (in time series), the contents of these Xth frames may be the same or different. X is an arbitrary value.

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. Depending on the situation, 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 present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying 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.

1: Access point (wireless terminal)
12A, 12B, 12C, 12D:

antennas

1, 2, 3, 4:

wireless terminals

1A, 2A, 3A, 4A:

antennas

21, 23, 25, 27: request frames 22, 22A: inquiry frames 28: notification frames 29 to 32: Data frame 33: BlockACK frame 101, 201: Control unit 102, 202: Transmission unit 103, 203: Reception unit 104, 204: Buffer 111, 211: Baseband unit 121, 221: RF unit 122, 222: Transmission circuit 123, 223: reception circuit 112, 212: control circuit 113, 213: transmission processing circuit 114, 214: reception processing circuit 115, 116, 215, 216: DA conversion circuit 117, 118, 217, 218: AD conversion circuit 301: Notebook PC
305, 315, 355: Wireless communication device 321: Mobile terminal 331: Memory card 332: Memory card body

Claims

At least one antenna;
A wireless communication unit for transmitting and receiving a frame via the antenna;
Receiving a first frame requesting permission for transmission via the wireless communication unit;
In response to the reception of the first frame, a second frame for inquiring whether there is a request for transmission to a second terminal different from the first terminal that transmitted the first frame is transmitted via the wireless communication unit,
Via the wireless communication unit, receiving a third frame to notify the presence or absence of the transmission request,
Based on the first frame and the third frame, a fourth frame specifying the third terminal permitted to transmit is transmitted via the wireless communication unit,
A wireless communication terminal comprising: a control unit that receives the fifth frame via the wireless communication unit after completing transmission of the fourth frame.
The wireless communication terminal according to claim 1, wherein the second frame includes first information for specifying the second terminal.
In the second frame, a plurality of identifiers of the second terminals are arranged in order,
The said control part receives the said 3rd frame transmitted after the completion of transmission of the said 2nd frame from the said 2nd terminal which has the identifier arrange | positioned in the predetermined position of the identifier arrange | positioned in order. The wireless communication terminal described.
The control unit sequentially selects a second terminal other than the second terminal having the identifier arranged at the predetermined position, and requests the selected second terminal to transmit the third frame. The wireless communication terminal according to claim 3, wherein a sixth frame is transmitted and the third frame is received as a response to the sixth frame.
The second frame includes second information for specifying a transmission timing of the third frame for each second terminal, and receives the third frames respectively transmitted at a transmission timing specified by the second information. Item 3. A wireless communication terminal according to Item 2.
In the second frame, the identifiers of the second terminals are arranged in order,
The wireless communication terminal according to claim 5, wherein the transmission timing of the third frame of the second terminal is determined by the order in which the identifiers of the second terminal are arranged.
Each of the plurality of devices belongs to at least one of at least one group;
The wireless communication terminal according to claim 2, wherein the first information includes a group identifier of one of the at least one group.
The first information further includes an identifier of one of the second terminals among terminals belonging to the one group, and is transmitted from the one second terminal after completion of transmission of the second frame. The wireless communication terminal according to claim 7, wherein the third frame is received.
The control unit transmits group information in which identifiers of terminals belonging to the one group are arranged in order to the terminals belonging to the one group,
The control unit receives the third frame transmitted after the transmission of the second frame is completed from the second terminal, which is the terminal having the identifier arranged at a predetermined position in the group information. The wireless communication terminal described.
The control unit sequentially selects second terminals other than the second terminal among the terminals belonging to the one group, and transmits a sixth frame requesting transmission of the third frame. The wireless communication terminal according to claim 8, wherein the third frame is received as a response of the sixth frame.
The control unit transmits group information in which identifiers of terminals belonging to the one group are arranged in order to the terminals belonging to the group,
8. The radio according to claim 7, wherein the control unit receives the third frame transmitted at a timing corresponding to an arrangement order of identifiers of the second terminals in the group information after the transmission of the second frame is completed. Communication terminal.
The wireless communication terminal according to claim 1, wherein the control unit receives the third frame transmitted from the second terminal according to CSMA / CA.
The wireless communication terminal according to any one of claims 1 to 12, wherein the second frame includes third information regarding a period during which reception of the third frame can be accepted.
The wireless communication terminal according to claim 13, wherein the control unit transmits the fourth frame after elapse of a period indicated by the third information.
The first frame and the third frame include the time for which transmission is desired, the data size desired for transmission, the number of streams for transmission, an error correction scheme, a modulation scheme, a coding scheme, or a channel for transmission. The radio | wireless communication terminal as described in any one of Claims 1 thru | or 14 including the information regarding at least 1 among these.
The wireless communication according to any one of claims 1 to 15, wherein the control unit receives the fifth frame transmitted by OFDMA (Orthogonal Frequency Division Multiple Access) or spatial multiplexing after the transmission of the fourth frame is completed. Terminal.
The wireless communication terminal according to claim 1, wherein the wireless communication terminal operates as an access point.
The wireless communication terminal according to any one of claims 1 to 17, wherein communication is performed in accordance with the IEEE 802.11 standard.
At least one antenna;
A wireless communication unit for transmitting and receiving a frame via the antenna;
Via the wireless communication unit, receiving a first frame inquiring whether there is a transmission request;
Based on the first frame, a first operation of transmitting a second frame for notifying the presence or absence of the request for data transmission after completion of reception of the first frame, or transmission of the second frame after reception of the first frame A wireless communication terminal comprising: a control unit that selects a second operation for transmitting the second frame in response to reception of the third frame requesting the second frame and executes the selected operation.
In the first frame, identifiers of a plurality of terminals are arranged in order,
The control unit executes the first operation when the identifier of the own device is disposed at a predetermined position among the identifiers disposed in the order, and is disposed at a position different from the predetermined position. The wireless communication terminal according to claim 19, wherein the second operation is executed.
The control unit receives group information in which identifiers of terminals belonging to a first group to which the device belongs are arranged in order,
The first frame includes a second group of identifiers;
The control unit selects and executes the first operation when the second group matches the first group and the identifier of the own device is arranged at a predetermined position in the group information, The second operation is selected and executed when the second group matches the first group and the identifier of the device is arranged at a position different from the predetermined position in the group information. Wireless communication terminal.
The first frame includes an identifier of a first group and an identifier of one terminal among terminals belonging to the first group;
The control unit selects and executes the first operation when the first group matches the second group to which the own device belongs and the identifier of the one terminal matches the identifier of the own device. The wireless communication terminal according to claim 19, wherein the second operation is selected and executed when the first group matches the second group and the identifier of the one terminal does not match the identifier of the own device.
The wireless communication terminal according to any one of claims 19 to 22, wherein communication is performed in accordance with the IEEE 802.11 standard.
A wireless communication method using a wireless communication terminal,
Receiving a first frame requesting permission to transmit;
In response to receiving the first frame, transmitting a second frame inquiring whether there is a transmission request to a second terminal different from the first terminal that transmitted the first frame;
Receiving a third frame notifying whether there is a request for transmission;
Transmitting a fourth frame designating a third terminal permitted to transmit based on the first frame and the third frame;
Receiving a fifth frame transmitted from the third terminal after completion of transmission of the fourth frame.
A wireless communication method using a wireless communication terminal,
Receiving a first frame inquiring whether there is a request for transmission;
Based on the first frame, a first operation of transmitting a second frame for notifying the presence or absence of the transmission request after completion of reception of the first frame, or transmission of the second frame after reception of the first frame Selecting a second operation for transmitting the second frame in response to reception of the requested third frame, and executing the selected operation.
A wireless communication system comprising a first wireless communication terminal and a plurality of second wireless communication terminals,
The first wireless communication terminal receives a first frame requesting permission for transmission from the second wireless communication terminal, and transmits the first frame in response to reception of the first frame. A second frame for inquiring whether there is a request for transmission is transmitted to another second radio communication terminal different from the terminal, and a third frame for notifying whether there is a request for transmission is received from the other second radio communication terminal. A fourth frame designating a third wireless communication terminal which is the second wireless communication terminal permitting the transmission based on the first frame and the third frame is transmitted, and after the transmission of the fourth frame is completed A first control unit for receiving a fifth frame transmitted from the third wireless communication terminal;
A first operation in which the second wireless communication terminal receives the second frame from the first wireless communication terminal, and transmits the third frame based on the second frame after the reception of the second frame is completed; Or selecting a second operation for transmitting the third frame in response to reception of a sixth frame requesting transmission of the third frame received from the first wireless communication terminal after receiving the second frame. A wireless communication system including a second control unit that executes the selected operation.
A wireless communication method between a first wireless communication terminal and a plurality of second wireless communication terminals,
The first wireless communication terminal receives a first frame requesting permission for transmission from one of the second wireless communication terminals, and transmits the first frame in response to reception of the first frame. A second frame that inquires about the presence or absence of the transmission request is transmitted to another second wireless communication terminal that is different from the second wireless communication terminal, and a third frame that notifies the presence or absence of the transmission request is transmitted to the other second wireless communication terminal. A fourth frame that is received from a communication terminal and that designates a third wireless communication terminal that is the second wireless communication terminal that performs the transmission is transmitted based on the first frame and the third frame, and the fourth frame Receiving a fifth frame transmitted from the third wireless communication terminal after transmission of
The other second wireless communication terminal receives the second frame from the first wireless communication terminal, and transmits the third frame based on the second frame after the reception of the second frame is completed. An operation or a second operation of transmitting the third frame in response to reception of a sixth frame requesting transmission of the third frame received from the first wireless communication terminal after receiving the second frame. A wireless communication method for selecting and executing a selected operation.