JP7015806B2 - Wireless communication device and wireless communication method - Google Patents

Description

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

Conventionally, as a method of managing a wireless channel, there is a method of performing virtual carrier sense by setting a NAV (Network Allocation Vector), which is a transmission prohibition period, based on the information of a received packet. The received packet may be from the BSS (Basic Service Set) to which the own terminal belongs or from another adjacent BSS, that is, the Overwrapping BSS (OBSS). The BSS to which the own terminal belongs is described as the own BSS, and the other BSS is described as the OBSS.

On the other hand, a method of performing different NAV management depending on whether the received packet is from the own BSS or the OBSS has also been proposed. The NAV set based on the packet received from the own BSS is called an Intra-BSS NAV, and the NAV set based on the packet received from the OBSS is called a Regular NAV.

Further, as a method for effectively utilizing a wireless channel, a Dynamic Sensitivity Control (DSC) has been proposed (also referred to as a spatial reuse). As a method using DSC technology, it is determined whether the packet is from the own BSS based on the BSS coloring information included in the header of the received packet, and the carrier sense threshold value, that is, CCA (Clear) is determined according to the determination result. Header Assessment) There is something that controls the threshold value.

It is conceivable to carry out the above-mentioned DSC in an environment that manages Intra-BSS NAV and Regular NAV. In this case, the method of specifically utilizing Intra-BSS NAV and Regular NAV is this. Not proposed until.

IEEE Std 802.11ac (TM) -2013 IEEE Std 802.11 (TM) -2012 IEEE 802.11-15 / 1326r2 IEEE 802.11-15 / 1348 IEEE 802.11-15 / 1067r0

An embodiment of the present invention provides a wireless communication device, a wireless communication terminal, and a wireless communication method that enable effective utilization of a wireless channel.

The wireless communication device according to the embodiment of the present invention sets at least one of a first transmission prohibition period for the first network to which the own device belongs and a second transmission prohibition period for the second network, and the first transmission prohibition period is set. When the first frame addressed to another device is received in a state where the second transmission prohibition period is set without being set, the reception level of the first frame is set to the first network and the second. A control unit for determining the state of the radio medium is provided in comparison with a threshold value corresponding to the network of the source of the first frame in the network.

The figure which shows the wireless communication system which includes a base station and a plurality of terminals. The figure for demonstrating DSC. The figure for demonstrating DSC. The figure which shows the basic format example of a MAC frame. The figure which shows the example of the packet format. The figure which shows the 1st sequence example which concerns on this embodiment. The flowchart of the operation example of the terminal which concerns on this embodiment. The figure which shows the 2nd sequence example which concerns on this embodiment. The figure which shows the 3rd sequence example which concerns on this embodiment. The figure which shows the 4th sequence example which concerns on this embodiment. The figure which shows the 5th sequence example which concerns on this embodiment. The figure which shows the 6th sequence example which concerns on this embodiment. The figure which shows the 7th sequence example which concerns on this embodiment. The flowchart of the other operation example of the terminal which concerns on this embodiment. The figure which shows the 8th sequence example which concerns on this embodiment. The flowchart of the other operation example of the terminal which concerns on this embodiment. The flowchart of the other operation example of the terminal which concerns on this embodiment. The block diagram of the wireless communication apparatus mounted on the access point which concerns on this embodiment. The block diagram of the wireless communication apparatus mounted on the terminal which concerns on this embodiment. The functional block diagram of the base station or the terminal which concerns on 2nd Embodiment. The figure which shows the whole composition example of the terminal or the base station which concerns on 3rd Embodiment. The figure which shows the hardware configuration example of the wireless LAN module mounted on the terminal or the base station which concerns on 3rd Embodiment. The perspective view of the wireless communication terminal which concerns on embodiment of this invention. The figure which shows the memory card which concerns on embodiment of this invention. The figure which shows an example of frame exchange in a contention period.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Specification framework documents for IEEE Std 802.11 (TM) -2012 and IEEE Std 802.11ac (TM) -2013, known as wireless LAN standards, and IEEE Std 802.11ax, the next generation wireless LAN standard. The IEEE 802.11-15 / 0132r17 uploaded on May 25, 2016, which is a Specialization Framework Document, shall be incorporated herein by reference in its entirety.

(First Embodiment)
The present embodiment relates to a wireless communication system that realizes effective use of a wireless channel in an environment in which a Regular NAV (Network Allocation Vector), an Intra-BSS NAV, and a DSC (Dynamic Sensitivity Control) can be implemented. In the present embodiment, a wireless LAN (Local Area Network) system compliant with IEEE802.11 is assumed, but the present invention is not limited thereto. In addition, DSC is sometimes called Physical Reuse.

Here, the NAV is a mechanism for virtually determining that the wireless medium is busy, or a period during which the medium is virtually determined to be busy. NAV corresponds to a transmission prohibition period, and when a wireless communication terminal (hereinafter referred to as a terminal) receives a MAC (Medium Access Control) frame addressed to another terminal, the MAC header starts from the end of the packet containing the MAC frame. The NAV is set based on the medium reservation time described in the Duration / ID field inside. The terminal is prohibited from accessing, that is, transmitting to the wireless medium while setting the NAV.

Intra-BSS NAV is the BSS (Basic Service) to which the own terminal belongs.
It is a NAV set based on the packet received from within Set). A Regular NAV is a NAV that is set based on a packet received from within another adjacent BSS, namely the Overwrapping BSS (OBSS). The BSS corresponds to the network formed by the access point.

The Dynamic Sensitivity Control (DSC) is a technology for improving the utilization efficiency of wireless channels by appropriately switching the carrier sense threshold value, that is, the CCA (Clear Channel Assistance) threshold value according to the environment.

In the wireless LAN, the terminal performs carrier sense and carrier sense during the standby time, which is the total of the predetermined time and the backoff time randomly determined by using random numbers, in order to acquire the access right. If the signal reception level is less than the CCA threshold, it is determined that the state of the wireless medium (carrier sense result) is idle, and the access right is acquired. If it is equal to or higher than the CCA threshold value, it is determined that the state of the wireless medium (carrier sense result) is busy, and the access right is not acquired. The operation including the carrier sense for acquiring this access right may be referred to as backoff processing in the following.

One of the features of the present embodiment is to control the implementation of DSC according to the setting state of the Intra-BSS NAV and the Regular NAV in the terminal and the BSS (network) of the transmission source of the received frame. As an example, when the Intra-BSS NAV is not set and the Regular NAV is set and a frame from OBSS is received, the terminal performs DSC. That is, as a threshold value to be compared with the reception level of the frame, a CCA threshold value higher than the initial value is used (that is, the value of the threshold value is changed). If the reception level of the frame is less than the CCA threshold value, the radio channel (radio medium) is determined to be idle, and the frame is transmitted even if Regular NAV is set.
In this way, even if Regular NAV is set, it is ignored and DSC is prioritized. This increases the chances of packet transmission and improves the utilization efficiency of wireless channels.
Hereinafter, the present embodiment will be described in detail.

FIG. 1 shows a wireless communication system according to the present embodiment. This wireless communication system includes an access point (AP: Access Point) 11 which is a base station, a terminal (STA: Station) 1A, and a terminal 1B. The access point 11 forms a BSS (Basic Service Set) 1, that is, a wireless network. The terminals 1A and 1B have already been connected to the access point 11 by performing an association process, and belong to BSS1. The access point 11 is a form of a terminal because it has the same functions as a terminal (station) except that it has a relay function. The term non-base station terminal refers to a station, but the term wireless communication terminal (terminal) may refer not only to a station but also to an access point.

There is another BSS2 adjacent to this BSS1. The BSS 2 is formed by the access point 21. The terminal 2A and the terminal 2B have already been connected to the access point 21 by performing an association process with the access point 21, and belong to BSS2.

In BSS1, communication is performed using at least one radio channel (here, one radio channel is assumed) selected from a plurality of radio channels arranged at fixed frequency intervals. It is assumed that communication is performed using the same wireless channel as BSS1 in BSS2. The above radio channel is a frequency channel. Hereinafter, the wireless channel may be simply referred to as a channel.

Hereinafter, an example in which the CCA threshold value is controlled by the DSC based on the wireless communication system shown in FIG. 1 will be shown. It is assumed that the terminal 1B in the BSS 1 has data to be transmitted to the access point 11. Since the terminal 1B acquires the access right to the wireless medium according to CSMA / CA (Carrier Sense Multiple Access with Carrier Assistance), the standby time (carrier sense) which is the total of a fixed period and a randomly determined backoff time. During the time), the carrier sense of the wireless medium is performed, and if the CCA value is less than the CCA threshold value, the access right is acquired. The CCA value represents the reception level of the signal received from the radio medium. For example, if the average CCA value at regular intervals during the standby time is less than the CCA threshold value, it is determined that the radio medium is idle, and the terminal 1B acquires the access right. The terminal 1B that has acquired the access right generates a MAC frame containing data, more specifically, a physical packet in which a physical header is added to the MAC frame, and transmits the physical packet to the space as a radio wave signal. On the other hand, if the CCA value exceeds the threshold value during the carrier sense, for example, if a time interval occurs in which the average CCA value at regular intervals exceeds the threshold value, the radio medium is regarded as busy and the back-off operation is performed. Stop. In this case, the career sense is redone if necessary.

Here, when the initial value (default CCA threshold value) given in advance as the CCA threshold value is set in the terminal 1B, the range (signal detection range) R1 in which the terminal 1B can detect the signal from another terminal. Is shown in FIG. As an example, it is conceivable to use -82 dBm as the initial value. However, the present invention is not limited to this. In the state shown in the figure, if the access point 21 transmits while the terminal 1B is performing carrier sense, the level of the signal received from the access point 21 at the terminal 1B becomes equal to or higher than the CCA threshold value, and thus the result of carrier sense. Becomes busy.

By increasing the CCA threshold value of the terminal 1B, the signal detection range of the terminal 1B can be narrowed. At this time, by setting the CCA threshold value so that the access point 21 in the BSS 2 is not included in the signal detection range of the terminal 1, the terminal 1B cannot detect the signal from the access point 21. An example of this is shown in FIG. In the example of FIG. 2, when the initial value of the CCA threshold value is −82 dBm, in the example of FIG. 3, it is conceivable to set the CCA threshold value to, for example, −62 dBm.
The signal detection range R2 of the terminal 1B in FIG. 3 is narrower than that of FIG. 2, and the access point 21 is not included in the signal detection range R2. Therefore, even if the access point 21 transmits a signal while the terminal 1B is performing carrier sense, the reception level of this signal is lower than the CCA threshold value at the terminal 1B, and the carrier sense result is idle.

In this way, by changing the CCA threshold value of the terminal 1B so as not to detect the signal from the BSS 2, the opportunity of transmission of the terminal 1B can be increased and the wireless channel can be effectively used. On the other hand, when DSC is performed, that is, when the CCA threshold value is increased, there arises a problem that the effective use of the radio channel in the own BSS1 is suppressed due to the signal collision with the hidden terminal in the own BSS1. The hidden terminal is a terminal having a positional relationship in which a signal transmitted by another terminal belonging to the same BSS cannot be detected. In the example of FIG. 3, the terminal 1A is a hidden terminal by the terminal 1B. Another problem with DSCs other than hidden terminals is interference with OBSS. On the other hand, it is also effective to perform control such as lowering the transmission power when the CCA threshold value is raised.

The above is the explanation of DSC. Next, an example in which the terminal manages the NAV separately as the Intra-BSS NAV and the Regular NAV will be described. Prior to this, the format of the MAC frame will be described.

FIG. 4A shows an example of a basic format of a MAC frame. The frame format includes MAC header, Frame body and FCS fields. As shown in FIG. 4 (B), the MAC header includes fields of Frame Control, Duration / ID, Addless1, Addless2, Addless3, Quality Control, QoS Control, and HT (High Throughput) control.

Not all of these fields need to be present, and some fields may not be present. For example, the Addless3 field may not exist.
Also, the QoS Control and HT Control fields may or may not be present. It is also possible that the frame body field does not exist.
There may also be other fields not shown in FIG. For example, there may be more Address4 fields.

The reception address (Receiver Address: RA) is entered in the field of Addlesss1, the source address (Transmitter Address: TA) is entered in the field of Address2, and the field of Addlesss3 is an identifier of BSS depending on the use of the frame. BSSID (Basic Service Set Identifier) or TA is entered. The BSSID may be a wildcard BSSID (all bits are 1) that targets all BSSIDs.

The Frame Control field includes two fields such as a type (Type) and a subtype (Subtype). The data frame, the management frame, and the control frame are roughly classified in the Type field, and the subtypes in the roughly classified frames are performed in the Subtype field. For example, the control frame includes a BA (Block Ac) frame, a BAR (Block Ac Request) frame, an RTS (Request to Send) frame, and a CTS (Clear to Send) frame, and the identification of these frames is Subtype. It is done in the field.

The Duration / ID field describes the media reservation time, and when a MAC frame addressed to another terminal is received, the medium is virtually busy from the end of the physical packet containing the MAC frame to the media reservation time. Is determined. Such a mechanism for virtually determining the medium to be busy, or a period for virtually determining the medium to be busy is called NAV (Network Allocation Vector), as described above. The QoS field is used to perform QoS control for transmission in consideration of the priority of the frame. The HT Control field is a field introduced in IEEE802.11n. The HT (High Throughput) Control field exists when the order field is set to 1 at the time of the QoS data or the management frame. The HT Control field is also VHT (Very High Throughput) Control field is also HE (High).
Efficient) It can also be extended to the Control field, and can notify according to various functions of IEEE802.11n, IEEE802.11ac, or IEEE802.11ax, respectively.

FCS (Frame Check Sequence) information is set in the FCS field as a checksum code used for frame error detection on the receiving side. As an example of FCS information, there is CRC (Cyclic Redundancy Code) and the like.

FIG. 5A shows an example of packet format. The basic structure of a packet is a MAC frame stored in a data field with a physical header added. Physical headers include, for example, L-STF (Legacy-Short Training Field), L-LTF (Legacy-Long Training Field), L-SIG (Legacy Signal) defined in the 802.11 standard. L-STF, L-LTF, and L-SIG are fields that can be recognized by terminals of legacy standards such as IEEE802.11a, and are signal detection, frequency correction (propagation path estimation), and transmission speed (transmission rate), respectively. Information such as is stored. The physical header may include a field other than those described here, for example, a field that cannot be recognized by a terminal of a legacy standard and can be recognized by a terminal compatible with IEEE802.11ax, which is a next-generation wireless LAN standard. For example, as shown in FIG. 5B, at least the former of HE-SIG-A and HE-SIG-B studied in IEEE802.11ax, HE-STF, HE-LTF and the like may be included. ..

Hereinafter, an example in which the terminal manages the NAV separately as the Intra-BSS NAV and the Regular NAV will be shown. FIG. 6 shows an example of a sequence of a wireless communication system for explaining the NAV management. Here, an example in which the terminal 1B (STA1B in the figure) manages these NAVs is shown. The terminal 1B can receive signals from the access point point 11 (AP11 in the figure) in the own BSS1 and the access point point 21 (AP21 in the figure) in the BSS2, but the terminal 1A in the BSS1 and the BSS2. It is assumed that the signal from the terminal 2A of the above cannot be received. Receivable means that the reception level of the signal is equal to or higher than the CCA threshold value, the frame can be received, and the Duration value related to the NAV setting can be acquired. In the following description, there is an expression of transmitting or receiving a frame, but in reality, a packet having a physical header added to the frame according to the type of the frame is transmitted or received.

The access point 11 acquires the access right to the wireless medium according to CSMA / CA and transmits the RTS frame 31. The RTS frame 31 is a frame that requests transmission permission from the other party. The terminal 1A receives the RTS frame 31, and after SIFS, transmits the CTS frame 32 that gives the transmission permission to the transmission source of the RTS frame 31. SIFS is an example of a fixed time, and is not limited to this. This also applies to the following description.

The RTS frame 31 is also received at the terminal 1B. Since the RTS frame 31 is addressed to another terminal (because RA is the MAC address of the other terminal), the terminal 1B has a NAV (transmission prohibition period) for a period corresponding to the value set in the Duration / ID field of the RTS frame 31. ) Is set. At this time, since the RTS frame 31 is a frame transmitted from within the own BSS 1, the terminal 1B sets the Intra-BSS NAV 61 as the NAV. The terminal 1B is prohibited from performing a transmission operation (including a backoff operation) while the Intra-BSS NAV61 is set.

There is a method of determining whether or not the network to which the source of the RTS frame 31 belongs is the own BSS1 based on the TA (Transmitter Address) of the RTS frame 31. Depending on the type of frame, BSS identification information may be stored in the header of the packet. In this case, there is a method of making a determination based on the BSS identification information (see FIG. 5C described later). An example of BSS identification information is BSS Coloring as defined in the 802.11 standard.

Upon receiving the CTS frame 32, the access point 11 transmits a data frame 33 including data for transmission to the terminal 1A after SIFS. The terminal 1A that has received the data frame 33 performs an error check based on the CRC information stored in the FCS field of the data frame 33, and if it is determined that there is no error, the terminal 1A transmits the ACK frame 34 after SIFS. The data frame 33 is also received by the terminal 1B, and the terminal 1B updates the Intra-BSS NAV 61 based on the Duration / ID field of the data frame 33. Here, it is assumed that there is no change in the time length of Intra-BSS NAV61 due to the update.

The data frame 33 is an A-MPDU (A (Aggregated) -MPDU (medium access control (MAC)) in which a plurality of MPDUs are connected.
Protocol data unit)) may be used, in which case a Block Ac (BA) frame is transmitted as a delivery acknowledgment (same below).

When the access point 11 receives the ACK frame 34 from the terminal 1A, the access point 11 transmits the CF-end frame 35. The CF-End frame is a frame that permits access to a wireless medium after acquiring a CFP (Contention Free Period) or an access right (transmission right). The CF-End frame 35 is received by the terminal 1A, and the terminal 1A can subsequently access by DCF (Distributed Coordination Foundation), that is, acquire an access right according to CSMA / CA and perform frame transmission. Judge. On the other hand, the CF-End frame 35 is also received at the terminal 1B. The terminal 1B determines whether the CF-End frame 35 is from the own BSS1 and, if it is determined that the CF-End frame 35 is transmitted from within the own BSS1, cancels the setting of the Intra-BSS NAV61.

On the other hand, in BSS2, the terminal 2A transmits the RTS frame 41, and the access point 21 transmits the CTS frame 42 after SIFS from the completion of receiving the RTS frame 41. Upon receiving the CTS frame 42, the terminal 2A transmits a data frame 43 including data for transmission to the access point 21 after SIFS.

The CTS frame 42 transmitted by the access point 21 is also received by the terminal 1B in the BSS1. The terminal 1B sets a NAV (transmission prohibition period) for a period corresponding to the value set in the Duration / ID field of the CTS frame 42. Here, since the CTS frame 42 is a frame transmitted from within the BSS2 (OBSS), the Regular NAV 62 is set.

However, since the CTS frame 42 includes the RA field but does not include the TA field, it may not be known from the CTS frame 43 alone whether it is transmitted from the OBSS or the own BSS. In this embodiment, in such a case, Regular NAV is set. In the following, some methods for determining whether the CTS frame is from the own BSS will be shown. If the terminal 1B can receive the RTS frame 41 transmitted by the terminal 2A in the BSS2, the terminal 1B sets the Regular NAV based on the RTS frame 41. Since it is known from the TA of the RTS frame 41 that the transmission destination is the BSS2, the terminal 1B in the BSS1 can understand that the network of the transmission source of the RTS frame 41 is the BSS2.

As a general rule, the terminal 1B is prohibited from performing a transmission operation (including a backoff operation) while the Regular NAV62 is set, but in the present embodiment, as will be described later, the Regular NAV62 is ignored. , One of the features is to carry out DSC.
After that, the terminal 1B releases the Regular NAV 62 when the period of the Regular NAV 62 elapses or when a CF-end frame is received from within the BSS2.

The setting example of Intra-BSS NAV and Regular NAV is shown above. In the present embodiment, the wireless channel is effectively used by appropriately implementing DSC in an environment where NAV management between Intra-BSS NAV and Regular NAV is performed. Hereinafter, the present embodiment will be described in more detail.

FIG. 7 is a flowchart of an operation for controlling the execution of DSC according to the setting status of the Intra-BSS NAV and the Regular NAV when the terminal has data for transmission. If at least the Intra-BSS NAV of the Intra-BSS NAV and the Regular NAV is set (YES in S101), the terminal does not perform the backoff operation and data transmission until the Intra-BSS NAV is released (YES in S101). S102). If the Intra-BSS NAV is not set, but the Regular NAV is set (YES in S103), the Regular NAV is ignored (S104), and the backoff operation for acquiring the access right for data transmission is performed. To start. That is, carrier sense is performed during the waiting time, which is the sum of the fixed time and the backoff time.

If a frame addressed to another terminal is not received (NO in S105) at a reception level equal to or higher than the initial CCA threshold value (for example, -82 dBm) during carrier sense, the result of carrier sense is judged to be idle and access is performed. Acquire the right (S109). On the other hand, when a frame addressed to another terminal is received at a reception level equal to or higher than the initial CCA threshold value (for example, -82 dBm) during carrier sense (YES in S105), whether the source of the frame is within the own BSS or not. It is determined whether it is within the OBSS (S106). There are various methods for determining whether or not the source of the frame is OBSS, but the details will be described later. The determination in step S106 may be made so that it can be determined whether or not it is OBSS from the header of the packet or the header of the frame, for example, in the middle of receiving the packet, even before the reception of the frame is completed. In the case of own BSS, that is, in the case of not OBSS (NO in S106), the result of carrier sense (radio medium) is determined to be busy, and the radio medium (radio channel) waits to be idle (S107). When the wireless channel becomes idle, the operation of this flow may be started from the beginning.

In the case of not own BSS, that is, in the case of OBSS, DSC is executed and the CCA determination is performed using the CCA threshold value for OBSS (for example, −62 dBm) which is larger than the initial CCA threshold value. That is, it is determined whether or not the reception level of the frame is less than the CCA threshold value for OBSS (S108). When the reception level is equal to or higher than the OBSS CCA threshold value, the carrier sense result is determined to be busy, and the radio medium (radio channel) waits to become idle (S107). When the wireless channel becomes idle, the operation of this flow may be started from the beginning.

On the other hand, if the reception level is less than the OBSS CCA threshold value, the backoff process is continued, and if the state below the OBSS CCA threshold value continues until the end of the waiting time, the carrier sense result is determined to be idle. Acquire the access right (S109). The terminal that has acquired the access right transmits a data frame containing data for transmission. If the backoff time elapses before the determination of whether the source of the frame is OBSS is completed, the transmission is waited until the determination is completed, and if it can be determined that the frame is OBSS, the data frame is transmitted. You may try to do it. Alternatively, in such a case, the data frame may be transmitted before the determination is completed.

According to the above-mentioned operation, it can be said that the Intra-BSS NAV, DSC, and Regular NAV are prioritized in this order. That is, when the Intra-BSS NAV is set, the packet interference caused by the hidden terminal or the like in the own BSS is reduced by not performing the DSC. When Intra-BSS NAV is not set, even if Regular NAV is set, it is ignored and DSC is prioritized to increase the chance of packet transmission. In this way, running the DSC in the appropriate circumstances will increase the utilization efficiency and throughput of the radio channel.

Here, a method of determining whether the received frame is from the own BSS or another BSS (OBSS) will be described.

(First method) When the TA or RA of the received frame is the BSSID (that is, the MAC address) of the access point of the BSS to which the own terminal belongs, the received frame is determined to be a frame from the own BSS.

(Second method) BSS color information (hereinafter referred to as color information) may be stored in the physical header, and a judgment can be made by using this. FIG. 5C shows an example of a packet format including a BSS Coloring field in a physical header. Color information (BSS identification information) is set in this field. The BSS Coloring field may be provided in the HE-SIG-A field of FIG. 5 (B). The access point or terminal that transmits the frame sets the identification information (color information) of its own BSS in the BSS color field of the physical header. The value of the color information is determined by the access point and notified to each terminal. Different values are determined as color information at least between adjacent BSSs. In this way, by using the color information, it is possible to determine whether or not the source of the received frame is within the own BSS.

(Third method) Depending on the type of frame, the BSS Coloring field may not exist in the physical header. For example, since the CTS frame, RTS frame, etc. need to be transmitted in a packet that can be interpreted by a legacy terminal (IEEE802.11a / b / g, etc.), it is conceivable that the physical header does not include the BSS Coloring field. Also, the CTS frame contains RA but not TA. Therefore, when the received frame is a CTS frame, it cannot be determined by the first and second methods whether or not the transmission source belongs to the own BSS. Therefore, the following method can be used.

That is, the RA of the frame addressed to another terminal (that is, the frame in which TA is the BSSID of the access point) transmitted so far from the access point of the own BSS is held in the terminal, and a list of RAs is created. When the CTS frame is received, it is determined whether the RA of the CTS frame is included in the RA list, and if it is included, it is determined that the CTS frame is from the own BSS. If it is not included in the RA list of CTS frames, the CTS frames may be considered to be from OBSS.

(Fourth Method) Another method for determining the source BSS when a CTS frame is received is shown. It is assumed that the terminal (including the case of an access point) receives the RTS frame, determines that it is a frame from its own BSS by the first method or the like, and sets the Intra-BSS NAV. In this case, when the CTS frame is received after a certain period of time (SIFS, etc.) from the reception of the RTS frame, it is determined that the CTS frame is a response frame for the RTS frame, and the CTS frame is transmitted from within the own BSS. Judge that it was done. Here, it is determined whether the source of the frame is from the own BSS, but it can also be determined from the OBSS by the same method.

Alternatively, the CTS frame is transmitted from the own BSS based on the relationship between the value set in the Duration / ID field of the RTS frame (Duration value) and the value set in the Duration / ID field of the CTS frame (Duration value). Determine if it was done. For example, if the value obtained by subtracting the SIFS and the CTS frame length from the Duration value set in the RTS frame matches the Duration value set in the CTS frame, the CTS frame is the response frame of the RTS frame. Judge. Therefore, it can be determined that the source of this CTS frame is within its own BSS. Here, it is determined whether the source of the frame is from the own BSS, but it can also be determined from the OBSS by the same method.

It should be noted that the BSS of the transmission source of the frame may be determined by using a method other than the first to fourth methods. If it cannot be determined whether the received frame is from the own BSS, it may be regarded as a frame transmitted from within the OBSS and processing may be performed. Alternatively, conversely, it is also possible to consider that the received frame is a frame transmitted from within the own BSS and perform processing.

Hereinafter, a sequence example of the wireless communication system when the terminal follows the operation of the flowchart of FIG. 7 will be shown. FIG. 8 shows a second example of a sequence of wireless communication systems. In the sequence of FIG. 6 described above, the operation of the terminal 1B managing two NAVs (Intra-BSS NAV and the Regular NAV) was shown, but here, in addition to this, the terminal 1B performs DSC to transmit. A sequence to do has been added. The description overlapping with FIG. 6 will be omitted. Hereinafter, the sequence of FIG. 8 will be described with reference to the flowchart of FIG. 7.

It is the same as FIG. 6 up to the point where the terminal 1B sets the Intra-BSS NAV61 and the Regular NAV62. The terminal 1B has the data to be transmitted to the access point 11, but does not perform the backoff process while the Intra-BSS NAV61 is set. The terminal 1B waits for the release of the Intra-BSS NAV61 with the passage of time (S102 in FIG. 7). When the Intra-BSS NAV61 is released, the Regular NAV62 is still set, but at present, the terminal 1B ignores this and starts the backoff process for acquiring the access right. During the carrier sense in the backoff process, it is determined whether a frame or signal having a level equal to or higher than the initial CCA threshold is received. Although the data frame 43 is transmitted from the terminal 2A, it is assumed that the reception level of the data frame 43 is lower than the initial CCA threshold value in the terminal 1B (NO in S105 of FIG. 7). The terminal 1B determines that the wireless medium is idle, acquires an access right, and transmits the RTS frame 51 (S109). It should be noted that the terminal 1B can determine OBSS from the color information stored in the header of the packet during the reception of the data frame 43.
In response to the RTS frame 51, the access point 11 transmits a CTS frame 52, and the terminal 1B transmits a data frame 53 including data for transmission to the access point 11.

Here, it is assumed that the reception level of the data frame 43 transmitted by the terminal 2A is lower than the initial CCA threshold value in the terminal 1B, but if it is equal to or higher than the initial CCA threshold value (YES in S105). At this time, the terminal 1B determines whether the transmission source of the data frame 43 is in the OBSS (S106 in FIG. 7). The terminal 1B determines whether it is in the OBSS by any of the above-mentioned first to fourth methods. For example, when the second method is used, the determination is made based on the color information included in the packet header of the data frame 43. The terminal 1B determines that the data frame 43 is a frame from the OBSS (YES in S106). The terminal 1B determines whether the reception level of the data frame 43 is less than the OBSS CCA threshold value (greater than the initial CCA threshold value). Here, the terminal 1B determines that the reception level of the data frame 43 is less than the CCA threshold value for OBSS (YES in S108), determines that the wireless medium is idle, acquires the access right, and transmits the RTS frame 51. (S109).

On the other hand, the operation when the terminal 1B determines that the reception level of the data frame 43 is equal to or higher than the OBSS CCA threshold value (NO in S108) will be described below. FIG. 9 shows a sequence example (third sequence example) in this case. The reception level of the data frame 43 in the terminal 1B is equal to or higher than the OBSS CCA threshold value, which is indicated by a dotted line extending from the data frame 43 on the time axis of the STA1B in the figure. In this case, the terminal 1B waits for the radio channel to become idle (S107). That is, it waits for a signal equal to or higher than the OBSS CCA threshold to be no longer received. Then, when it becomes idle, the operation of the flow of FIG. 7 may be started again. In the example of FIG. 9, the access point 21 transmits the ACK frame 44 to the data frame 43. Since the period of the Regular NAV62 was until the end of the ACK frame 44, the terminal 1B releases the Regular NAV62 at this point. Since the terminal 1B started the backoff process and did not receive the frame or signal at the reception level equal to or higher than the initial CCA threshold value (NO in S105), it acquired the access right (S109) and transmitted the RTS frame 51. There is.

In the sequence shown in FIG. 8, it is assumed that the RTS frame 36 addressed to the terminal 1A is received from the access point 11 in the own BSS1 during the Regular NAV 62 (assuming that the Intra-BSS NAV is terminated at this time). The operation of the case (NO in S106) will be described. FIG. 10 shows a sequence example (fourth sequence example) in this case. The terminal 1B receives the RTS frame 36 at a level equal to or higher than the initial CCA threshold value (YES in S105), but performs DSC because it is a frame from its own BSS1, that is, it is not a frame from OBSS (NO in S106). do not have. The terminal 1B waits for the radio channel to become idle (S107). At this time, the terminal 1B sets the Intra-BSS NAV63 again based on the value set in the Duration / ID field of the RTS frame 35, and waits at least between the Intra-BSS NAV63.

Next, a sequence example including an operation of determining that the source of the CTS frame is in the own BSS and setting the Intra-BSS NAV by using the third or fourth method described above is shown. FIG. 11 shows the sequence example (fifth sequence example). The terminal 1A in the BSS 1 transmits the RTS frame 52, and the access point 11 receives the RTS frame 52. The RTS frame 52 is not received at terminal 1B (the reception level is below the initial CCA threshold).
The access point 11 transmits the CTS frame 53 after SIFS from the completion of receiving the RTS frame 52. RA of CTS frame 53 is the MAC address of terminal 1A, and TA does not exist. The CTS frame 53 is received by the terminal 1B together with the terminal 1A. Upon receiving the CTS frame 53, the terminal 1A transmits the data frame 54 to the access point 11 after SIFS. On the other hand, in the terminal 1B, the NAV is set based on the value set in the Duration / ID field of the CTS frame 53. At this time, the terminal 1B determines whether the source of the CTS frame 53 is in the own BSS1 or in the OBSS by using the third or fourth method described above. For example, if the third method is used, the TA of the frame addressed to another terminal previously transmitted by the access point 11 is retained (from the TA of the frame, it can be seen that the source of the frame is the access point 11. ), It is determined whether the RA of the CTS frame 53 received this time matches the RA held. This time, since they match, it is determined that the source of the CTS frame 53 is within the own BSS1. Therefore, the terminal 1B sets the Intra-BSS NAV 64 as the NAV. When the access point 11 succeeds in receiving the data frame 54, the access point 11 transmits the ACK frame 55 after SIFS, and further transmits the CF-End frame 56 after the SIFS.
It is also possible to configure the CF-End frame 56 without transmitting it. Since the terminal 1B sets the Intra-BSS NAV64 according to the CTS frame 53, the backoff process is not performed at least until the period of the Intra-BSS NAV64 is completed by the operation of the flowchart of FIG. 7 described above. Since the operations other than this are the same as those in FIG. 8, the description thereof will be omitted.

Here, suppose that the terminal 1B cannot execute the first to fourth methods and cannot determine whether the source of the CTS frame 53 is in its own BSS or in the OBSS (first to first). The same applies if you do not understand even if you execute method 4). It is conceivable that the NAV to be set when such a determination cannot be made is a Regular NAV. FIG. 12 shows a sequence example (sixth sequence example) in which the Regular NAV is set in such a case. The terminal 1B receives the CTS frame 53, but does not know whether the source of the CTS frame 53 is its own BSS1 or OBSS. Therefore, Regular NAV65 is set. Since the terminal 1B follows the operation shown in FIG. 7, if the Intra-BSS NAV is not set, even if the Regular NAV65 is set, this is ignored. Therefore, the terminal 1B acquires the access right (S109) and transmits the RTS frame 51 even though the terminal 1A transmits the data frame 54 to the access point 11. As a result, the RTS frame 51 and the data frame 54 collide with each other, and the access point 11 fails to receive the data frame 54. On the other hand, in the sequence example of FIG. 11 described above, since it can be determined that the source of the CTS frame 53 is within the own BSS 1, the Intra-BSS NAV 64 can be set. Therefore, it is possible to prevent the problem as shown in the sequence of FIG. 12 from occurring. Although it is drawn as if the two Regular NAVs 62 and 65 are managed in FIG. 12, the Regular NAV65 set in response to the reception of the CTS frame 53 can be updated in response to the reception of the CTS frame 42. , Regular NAV may be centrally managed.

In the sequence example of FIG. 12, the terminal 1B could not receive the RTS frame 52 transmitted from the terminal 1A, but if the terminal 1B can receive the RTA frame 52, the problem as shown in FIG. 12 can be prevented. A sequence example (seventh sequence example) in this case is shown in FIG. When the terminal 1B receives the RTS frame 52, it can be seen from the RA of the RTS frame 52 that the destination is the access point 11. Therefore, it can be determined that the source of the RTS frame 52 is within the own BSS1. Therefore, the terminal 1B sets the Intra-BSS NAV66 as the NAV. In the situation where the Intra-BSS NAV is set, the terminal 1B refrains from the transmission operation, so that the collision problem described in FIG. 12 does not occur. Since other operations are the same as those in FIG. 11, the description thereof will be omitted.

In the sequence example of FIG. 12 described above, since the terminal 1B set the Regular NAV65 in response to the reception of the CTS frame 53, DSC was performed according to the operation of the flow of FIG. As a result, the terminal 1B acquires the access right and transmits the RTS frame 51, which collides with the data frame 54 at the access point 11. In the sequence example of FIG. 13, this problem can be prevented by receiving the RTS frame before the CTS frame 53, but in the following, a method of solving this problem by a method different from that of FIG. 13 is described below. Describe in.

FIG. 14 is a flowchart of another operation of the terminal according to the present embodiment. Step S104 in FIG. 7 is replaced with step S111, and step S112 is added between steps S106 and S108.

If it is determined in step S103 that the Regular NAV is set, in step S111, the Regular NAV address is specified. The Regular NAV address is the address of the frame that caused the current Regular NAV to be set. Specifically, RA and TA of the frame, or RA when TA does not exist (hereinafter referred to as RA / TA).

For example, if the frame that caused the Regular NAV is a CTS frame, the RA of the CTS frame corresponds to the Regular NAV address (even if the source of the CTS frame is actually in its own BSS, the source is unknown. (Including the case where Regular NAV is set by this).

Also, if another frame (eg, an RTS frame from OBSS) is received after the CTS frame and the Regular NAV is updated by this, the address (RA / TA) of this other frame is also specified. When Regular NAV is managed individually instead of centrally managed, the address of the frame that caused each is specified for each currently set Regular NAV.

If it is determined in step S106 that the source of the frame is within the OBSS, the process proceeds to step S112. The address (RA / TA) of the frame (for example, the data frame) received this time is compared with the Regular NAV address, and it is determined whether the Regular NAV address matches the address (RA / TA). If they match, DSC is executed (S108, S109). If they do not match, DSC is not executed (S108). For example, if there are three Regular NAV addresses, two of which match one of the RA and TA of the address of the frame received this time, but the other one does not match any of these RA and TA. , Do not run DSC.

FIG. 15 is a diagram showing a sequence example (eighth sequence example) for explaining a specific example of the operation of FIG.

The terminal 1A in the BSS1 transmits the RTS frame 71, and the access point 72 responds to the transmission of the CTS frame 72. The CTS frame 72 is received by the terminal 1A and the terminal 1B. The terminal 1A transmits the data frame 73 after SIFS from the completion of receiving the CTS frame 72. Further, the terminal 1B determines that the source of the CTS frame 72 is not known whether it is the own BSS or the OBSS, and sets the Regular NAV67 based on the value of the Duration / ID field of the CTS frame 72.

On the other hand, the access point 21 in the BSS2 transmits the RTS frame 74, and the RTS frame 74 is received by the terminal 2A and also by the terminal 1B in the BSS1. The terminal 2A transmits the CTS frame 75 in response to the RTS frame 74, and the access point 21 transmits the data frame 76 after SIFS from the completion of receiving the CTS frame 75. The data frame 76 is received by the terminal 2A and also by the terminal 1B.

Since neither RA nor TA of the RTS frame 74 is the BSSID (MAC address of the access point 11) of its own BSS1, the terminal 1B determines that the source of the RTS frame 74 is in the OBSS. Therefore, the terminal 1B sets the Regular NAV 68 based on the value of the Duration / ID field of the RTS frame 74.

It is assumed that in the terminal 1B, data for transmission to the access point 11 is generated before or while the data frame 76 is received from the access point 21, and a transmission request for the RTS frame is generated. In this case, the terminal 1B performs processing according to the operation of FIG. 14 in order to acquire the access right. In the flow of FIG. 14, the Intra-BSS NAV is not set (NO in S101), but the Regular NAV is set, so the Regular NAV address is specified (S111).

The Regular NAV addresses are RA (MAC address of terminal 1A) of CTS frame 72 that caused Regular NAV67 and TA and RA (MAC address of access point 21 and terminal 2A) of RTS frame 75 that caused Regular NAV68. MAC address).

The data frame 76 is received at a level equal to or higher than the initial CCA threshold value (YES in S105), and the source of the data frame 76 is determined to be in the OBSS, for example, from the BSS color information in the packet header (YES in S106). ). The terminal 1B determines whether the Regular NAV address matches either TA or RA of the data frame 76 (S112).

The TA and RA of the data frame 76 are the MAC address (BSSID) of the access point 21 and the MAC address of the terminal 2A, respectively. Therefore, the MAC address of the terminal 1A, which is one of the Regular NAV addresses, does not match any of the TA and RA of the data frame 76 (NO in S112).

Therefore, the terminal 1B does not execute the DSC and waits for the channel to become idle (S107). As a result, the transmission of the RTS frame from the terminal 1B is blocked (see the RTS surrounded by the broken line frame in FIG. 15). If the terminal 1B transmits an RTS frame, this collides with the data frame 73 transmitted from the terminal 1A, but the DSC is controlled not to be executed due to the address mismatch, so that the occurrence of this problem can be prevented. ..

Hereinafter, a modified example of the operation of the flowchart of FIG. 14 will be described.
(First modification) In the flowchart of FIG. 14, when both TA and RA are present in the frame that caused Regular NAV, both are held as Regular NAV addresses for comparison in step S112. Using. Alternatively, only RA may be retained and only RA may be used for comparison. In the case of the sequence example of FIG. 15, of the TA and RA of the RTS frame 74, only RA may be retained and TA may not be retained.

(Second modification) A step is performed so that the number of Regular NAV addresses is counted, and if the number is 3 or more, it is determined not to execute DSC, and if it is 2 or less, it is determined to execute DSC. The processing of S112 may be replaced.

(Third variant example) When two or more OBSSs exist and Regular NAV is set for a plurality of OBSSs, the Regular NAV address is held for each OBSS. In step S112, the processing of step S112 may be extended so that DSC is not executed if the condition of address matching is not satisfied for any one OBSS.

(Fourth modification)
If another Regular NAV is added in the middle of the Regular NAV (when the Regular NAV is centrally managed, the Regular NAV is updated), the process of step S112 is modified so that it is decided not to execute the DSC. May be good. In the example of FIG. 15, it is determined that the DSC is not executed because another Regular NAV 68 is set due to the RTS frame 74 in the middle of the Regular NAV 67 set due to the CTS frame 72.

(Fifth variant)
If the frame causing the Regular NAV is a CTS frame, the process of step S112 may be modified so as to decide not to execute the DSC and to execute the DSC in other cases. In the example of FIG. 15, since the frame that caused the Regular NAV 67 is the CTS frame 72, it is determined that the DSC is not executed. In this method, even if only the CTS frame from the OBSS is received and the Regular NAV is set, the DSC is not executed. Therefore, the chance of interference with the own BSS can be reduced, and it becomes difficult to obtain the effect of DSC.

FIG. 16 is a flowchart of still another operation example of the terminal according to the present embodiment. When step S104 in FIG. 7 is deleted and it is determined that Regular NAV is set (YES in S103), the release of Regular NAV is awaited (S113). Until now, Regular NAV was ignored, but in the operation flow of FIG. 7, not only Intra-BSS NAV but also Regular NAV is set, the NAV is released. Other operations are the same as in FIG. 7. In this example, the Intra-BSS NAV and the Regular NAV are not distinguished (treated as the same priority).

FIG. 17 is a flowchart of still another operation example of the terminal according to the present embodiment. Steps S101 to S104 in FIG. 7 have been deleted. Regardless of whether Intra-BSS NAV or Regular NAV is set, these are ignored and DSC is executed preferentially.

FIG. 18 is a functional block diagram of a wireless communication device mounted on the access point 11 according to the present embodiment.

The wireless communication device of the access point 11 includes a control unit 101, a transmission unit 102, a reception unit 103, an antenna 12 (12A, 12B, 12C, 12D), and a buffer 104. The number of antennas is four here, but at least one antenna may be provided. The control unit 101 corresponds to a control unit that controls communication with a terminal, and the transmission unit 102 and the reception unit 103 form a wireless communication unit that transmits and receives frames via an antenna. All or part of the processing of the control unit 101 and the processing of the digital area of the transmission unit 102 and the reception unit 103 may be performed by software (program) running on a processor such as a CPU, or may be performed by hardware. It may be done by both these software and hardware. The access point may include a processor that performs all or part of processing of the control unit 101, the transmission unit 102, and the reception unit 103.

The buffer 104 is a storage unit for passing data or the like between the upper layer and the control unit 101. The buffer 104 may be a volatile memory such as DRAM or SRAM, or a non-volatile memory such as NAND or MRAM. The upper layer processes a protocol higher than the MAC layer, such as TCP / IP or UDP / IP. The upper layer may store the data received from another network in the buffer 104 for relaying to the networks on the terminal 1A and terminal 2B sides. Further, the control unit 101 may pass the data received from the network on the terminal 1A and the terminal 2B side to the upper layer via the buffer 104. The TCP / IP and UDP / IP processing may be performed by the control unit 101, and the processing of the application layer higher than that may be performed by the upper layer. The operation of the upper layer may be performed by processing software (program) by a processor such as a CPU, may be performed by hardware, or may be performed by both software and hardware.

The control unit 101 mainly performs all or part of the processing of the MAC layer and the processing of the physical layer. The control unit 101 controls communication with each terminal by transmitting and receiving a frame (more specifically, a packet having a physical header added to the frame; the same applies hereinafter) via the transmission unit 102 and the reception unit 103. Further, the control unit 101 may be controlled to transmit a beacon frame in order to periodically notify the BSS (Basic Service Set) attribute of the access point, synchronization information, and the like. Further, the control unit 101 may include a clock generation unit that generates a clock, and may manage the internal time by using the clock generated by the clock generation unit. The control unit 101 may output the clock created by the clock generation unit to the outside. Alternatively, the control unit 101 may be generated by an external clock generation unit, receive a clock input, and use the clock to manage the internal time.

The control unit 101 receives an association request from a terminal, performs an association process, and exchanges necessary information such as abilities and attributes with each other to establish a wireless link with the terminal. When the association process is successful, the control unit 101 assigns an identifier (AID: Association ID) for identifying the terminal in the BSS to the effect that the association process is successful (the Status Code field is "0", that is, The association response including the AID is transmitted together with the access). If necessary, an authentication process may be performed with the terminal in advance.

By periodically checking the buffer 104, the control unit 101 may grasp the state of the buffer 104, such as whether or not there is data addressed to the terminal. Alternatively, the control unit 101 may confirm the state of the buffer 104 by an external trigger.

The control unit 101 controls to transmit a frame at a timing when an access right to the wireless medium is acquired according to CSMA / CA, a predetermined timing, or the like. When transmitting a data frame or the like, the RTS frame may be transmitted before the transmission, and the data frame or the like may be transmitted when the CTS frame can be received from the other party's device. Further, in the Duration / ID field of the MAC header of the frame to be transmitted (data frame, RTS frame, CTS frame, ACK frame, etc.), a value corresponding to the media reservation period is set.

The control unit 101 transmits the generated frame from the transmission unit 102 on the wireless channel to be used (for example, a channel width of 20 MHz). The transmission unit 102 adds a physical header to the input frame, encodes it, modulates it, and performs DA conversion, filter processing to extract desired band components, and frequency conversion (up-conversion) for the modulated physical packet. ) Etc.
The frequency-converted signal is amplified by a preamplifier and radiated as radio waves from one or more antennas into space.

The signal received by the antenna 12 is input to the receiving unit 103. The receiving unit 103 amplifies the received signal by a low noise amplifier (LNA), and frequency-converts (down-converts) the received signal based on the signal having a constant frequency. From the down-converted signal, a signal in the desired band is extracted by filtering processing, the extracted signal is converted to a digital signal by AD conversion, demodulation, error correction decoding, physical header processing, etc. are performed, and then the control unit. A frame is input to 101. The control unit 101 determines whether or not there is an error in the frame by performing a CRC inspection of the frame. When the control unit 101 receives a frame that requires a delivery confirmation response, the control unit 101 controls to transmit the delivery confirmation response (ACK frame, BA frame, etc.) to the terminal according to the result of the CRC inspection.

A selector for switching the connection destination of the antenna 12 between the transmission unit 102 and the reception unit 103 may be provided, and the connection destination of the antenna 12 may be switched between the time of transmission and the time of reception.

Here, the control unit 101 manages the Intra-BSS NAV and the Regular NAV. Even if the control unit 101 centrally manages the Intra-BSS NAV, the control unit 101 may individually manage the Intra-BSS NAV for each frame that causes the Intra-BSS NAV. Similarly, even if the control unit 101 centrally manages the Regular NAV, the Regular NAV may be individually managed for each frame that causes the Regular NAV. The Intra-BSS NAV corresponds to the transmission prohibition period for the own BSS, and the Regular NAV corresponds to the transmission prohibition period for the OBSS. Further, the control unit 101 controls the execution of the DSC according to the setting state of the Intra-BSS NAV and the Regular NAV and the network of the source of the frame addressed to another terminal that has been received. Examples of how to control the implementation of DSC, how to set the Intra-BSS NAV and Regular NAV, and how to determine the network (BSS) of the source of the frame are shown in FIGS. 7, 14, 16, and 16. It is as described in the flowchart of FIG. 17, and the sequence of FIGS. 8 to 13 and 15.

The control unit 101 may access and read out the information notified to each terminal by a frame or the like, the information notified from each terminal, or a storage device for storing both of them. The storage device may be an internal memory, an external memory, a volatile memory, or a non-volatile memory. In addition to the memory, the storage device may be an SSD, a hard disk, or the like.

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

FIG. 19 is a functional block diagram of a wireless communication device mounted on the terminal according to the present embodiment.
Among the functions of the access point described with reference to FIG. 18, this wireless communication device basically has the same functions as the access point except that it does not have a function related to relay.

The wireless communication device includes a control unit 201, a transmission unit 202, a reception unit 203, at least one antenna 1A, and a buffer 204. The control unit 201 corresponds to a control unit that controls communication with the access point 11, and the transmission unit 202 and the reception unit 203 correspond to a wireless communication unit that transmits and receives frames. 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) running on a processor such as a CPU, or may be performed by hardware. It may be done by both these software and hardware. The terminal may include a processor that performs all or part of the processing of the control unit 201, the transmission unit 202, and the reception unit 203.

The buffer 204 is a storage unit for passing data or the like between the upper layer and the control unit 201. The buffer 204 may be a volatile memory such as DRAM or a non-volatile memory such as NAND or MRAM. The upper layer processes a protocol higher than the MAC layer, such as TCP / IP or UDP / IP. The upper layer generates data to be transmitted to another terminal, an access point 11, or a device on another network such as a server, and stores the data in the buffer 204. Further, the data received from another terminal, access point, device, or the like may be passed from the control unit 201 to the upper layer via the buffer 204. The TCP / IP and UDP / IP processing may be performed by the control unit 201, and the processing of the application layer higher than that may be performed by the upper layer. The operation of the upper layer may be performed by processing software (program) by a processor such as a CPU, may be performed by hardware, or may be performed by both software and hardware.

The control unit 201 mainly performs all or part of the processing of the MAC layer and the processing of the physical layer. The control unit 201 controls communication with the access point by transmitting and receiving a frame (more specifically, a packet having a physical header added to the frame; the same applies hereinafter) via the transmission unit 202 and the reception unit 203. The control unit 201 may include a clock generation unit that generates a clock, and may manage the internal time by using the clock generated by the clock generation unit. The control unit 201 may output the clock created by the clock generation unit to the outside. Alternatively, the control unit 201 may be generated by an external clock generation unit, receive a clock input, and use the clock to manage the internal time.

As an example, the control unit 201 receives a beacon frame, grasps the BSS attributes and synchronization information of the access point 11, and then makes an association request to the access point 11 to perform an association process. As a result, a wireless link is established with the access point 11 by exchanging necessary information such as abilities and attributes of each other. If the association process is successful, the AID assigned to the own terminal is grasped from the association response. If necessary, an authentication process may be performed with the access point in advance.

By periodically checking the buffer 204, the control unit 201 may grasp the state of the buffer 204, such as the existence of data for uplink transmission. Alternatively, the control unit 201 may confirm the state of the buffer 204 by an external trigger.

After confirming the existence of data for uplink transmission, the control unit 201 acquires an access right (transmission right) to the wireless medium based on CSMA / CA or the like, and then transmits a frame (data frame) containing the data. Transmission is performed via unit 202 and antenna 1A. The RTS frame may be transmitted before the data frame is transmitted, and the data frame may be transmitted when the CTS frame can be received from the other party's device. In the Duration / ID field of the MAC header of the frame to be transmitted (data frame, RTS frame, CTS frame, ACK frame, etc.), a value corresponding to the media reservation period is set.

The control unit 201 transmits the generated frame from the transmission unit 202 on the wireless channel to be used (for example, a channel width of 20 MHz). The transmission unit 202 performs DA conversion, filter processing for extracting desired band components, frequency conversion (up-conversion), etc. for the physical packet after modulation by adding a physical header to the input frame, encoding, and modulation processing. ) Etc.
The frequency-converted signal is amplified by a preamplifier and radiated as radio waves from one or more antennas into space.

The signal received by the antenna 1A is input to the receiving unit 203. The receiving unit 203 amplifies the received signal by a low noise amplifier (LNA: Low Noise Amplifier), and frequency-converts (down-converts) the received signal based on the signal having a constant frequency. From the down-converted signal, a signal in the desired band is extracted by filtering processing, the extracted signal is converted to a digital signal by AD conversion, demodulation, error correction decoding, physical header processing, etc. are performed, and then the control unit. A frame is input to 201. The control unit 201 determines whether or not there is an error in the frame by performing a CRC inspection of the frame. When the control unit 201 receives a frame that requires a delivery confirmation response, the control unit 201 controls to transmit the delivery confirmation response (ACK frame, BA frame, etc.) to the terminal according to the result of the CRC inspection.

Here, the control unit 201 manages the Intra-BSS NAV and the Regular NAV. Even if the control unit 201 centrally manages the Intra-BSS NAV, the control unit 201 may individually manage the Intra-BSS NAV for each frame that causes the Intra-BSS NAV. Similarly, even if the control unit 201 centrally manages the Regular NAV, the Regular NAV may be individually managed for each frame that causes the Regular NAV. The Intra-BSS NAV corresponds to the transmission prohibition period for the own BSS, and the Regular NAV corresponds to the transmission prohibition period for the OBSS. Further, the control unit 201 controls the execution of the DSC according to the setting state of the Intra-BSS NAV and the Regular NAV and the network of the source of the frame addressed to another terminal that has been received. Examples of how to control the implementation of DSC, how to set Intra-BSS NAV and Regular NAV, and examples of how to determine the source network (BSS) of a frame are FIGS. 7, 14, and 16. , As described in the flowchart of FIG. 17, and the sequences of FIGS. 8 to 13 and 15.

A selector for switching the connection destination of the antenna 1A between the transmission unit 202 and the reception unit 203 may be provided, and the connection destination of the antenna 1A may be switched between the time of transmission and the time of reception.

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

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

(Second embodiment)
FIG. 20 is a functional block diagram of the base station (access point) 400 according to the second embodiment. This access point includes a communication processing unit 401, a transmitting unit 402, a receiving unit 403, antennas 42A, 42B, 42C, 42D, a network processing unit 404, a wired I / F 405, and a memory 406. .. The access point 400 is connected to the server 407 via a wired I / F 405. The communication processing unit 401 has the same function as the control unit described in the first embodiment. The transmitting unit 402 and the receiving unit 403 have the same functions as the transmitting unit and the receiving unit described in the first embodiment. The network processing unit 404 has the same functions as the control unit and the upper layer processing unit described in the first embodiment. Here, the communication processing unit 401 may internally hold a buffer for transferring data to and from the network processing unit 404. This buffer may be a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM.

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

As an example, the communication processing unit 401 corresponds to a baseband integrated circuit, and the transmitting unit 402 and the receiving unit 403 correspond to an RF integrated circuit that transmits and receives frames. The communication processing unit 401 and the network processing unit 404 may be configured by one integrated circuit (1 chip). The digital region processing portion and the analog region processing portion of the transmission unit 402 and the reception unit 403 may be configured by different chips. Further, the communication processing unit 401 may execute communication processing higher than the MAC layer such as TCP / IP and UDP / IP. Further, although the number of antennas is four here, it is sufficient that at least one antenna is provided.

The memory 406 stores the data received from the server 407 and the data received by the receiving unit 403. The memory 406 may be, for example, a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM. Further, SSD, HDD, SD card, eMMC and the like may be used. The memory 406 may be outside the base station 400.

The wired I / F 405 sends / receives data to / from the server 407. In the present embodiment, the communication with the server 407 is performed by wire, but the communication with the server 407 may be performed wirelessly. In this case, a wireless I / F may be used instead of the wired I / F 405.

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

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

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

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

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

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

By such an operation, the frequently accessed data responds based on the cache data stored in the memory 406, and the traffic between the server 407 and the base station 400 can be reduced. The operation of the network processing unit 404 is not limited to the operation of the present embodiment. Any general cache proxy that fetches data from server 407 instead of STA, caches the data in memory 406, and responds to data transfer requests for the same data from the cached data in memory 406. For example, there is no problem with another operation.
Further, the information obtained by the frame, data or packet received by the base station of the first embodiment may be cached in the memory 406. In the first embodiment, the frame transmitted by the access point may include cached data or information based on the data. The information based on the data may be, for example, information on the presence or absence of data addressed to the terminal, information on the size of the data, and information on the size of the packet required for transmitting the data. It may also be information such as a modulation method required for data transmission.

Although the base station having a cache function has been described in the present embodiment, a terminal (STA) having a cache function can be realized with the same block configuration as in FIG. 20. In this case, the wired I / F 405 may be omitted. The terminal referred to here is a terminal of a non-base station (as described above, a base station is also a form of a wireless communication terminal). The transmission of frames, data or packets by the terminal in the first embodiment described above may be executed using the cached data stored in the memory 406. Further, the information obtained by the frame, data or packet received by the terminal of the first embodiment may be cached in the memory 406. In the first embodiment, the frame transmitted by the terminal may include cached data or information based on the data. The information based on the data may be, for example, information on the presence or absence of data to be transmitted, information on the size of the data, and information on the size of the packet required for transmitting the data. It may also be information such as a modulation method required for data transmission.

(Third embodiment)
FIG. 21 shows an example of the overall configuration of a terminal or a base station. This configuration example is an example, and the present embodiment is not limited thereto. The terminal or base station includes one or more antennas 1 to n (n is an integer of 1 or more), a wireless LAN module 148, and a host system 149. The wireless LAN module 148 corresponds to the wireless communication device according to the first embodiment. The wireless LAN module 148 includes a host interface, which is connected to the host system 149. In addition to being connected to the host system 149 via a connection cable, it may be directly connected to the host system 149. Further, the wireless LAN module 148 can be mounted on the board by solder or the like and connected to the host system 149 via the wiring of the board. The host system 149 communicates with an external device by using the wireless LAN module 148 and the antennas 1 to n according to an arbitrary communication protocol. The communication protocol may include TCP / IP and a higher layer protocol. Alternatively, TCP / IP may be mounted on the wireless LAN module 148, and the host system 149 may execute only the protocol of the upper layer thereof. In this case, the configuration of the host system 149 can be simplified. This terminal is, for example, a mobile terminal, TV, digital camera, wearable device, tablet, smartphone, game device, network storage device, monitor, digital audio player, Web camera, video camera, project, navigation system, external adapter, internal It may be an adapter, a set-top box, a gateway, a printer server, a mobile access point, a router, an enterprise / service provider access point, a portable device, a handheld device, a car, or the like.
In addition to IEEE802.11, the wireless LAN module 148 (or wireless communication device) may have functions of other wireless communication standards such as LTE (Long Term Evolution) or LTE-Advanced (standards for mobile phones). ..

FIG. 22 shows a hardware configuration example of the wireless LAN module. This configuration is applicable when the wireless communication device is mounted on either a non-base station terminal or a base station. That is, it can be applied as an example of a specific configuration of the wireless communication device shown in FIG. In this configuration example, at least one antenna 247 is provided. When a plurality of antennas are provided, 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. Each set may be connected to the control circuit 212. The PLL 242, the crystal oscillator 243, or both correspond to the oscillator according to this embodiment.

The wireless LAN module (wireless communication device) is a baseband IC (Integrated).
It includes a 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. DAC216 and / or ADC217 may be located in the RF IC 221 or in another IC. Further, the memory 213 and / or the CPU 215 may be arranged in an IC different from the baseband IC.

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

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

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

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

The baseband circuit 212 performs physical header addition, coding, encryption, modulation processing, etc. on the frame to be transmitted as physical layer processing, for example, two types of digital baseband signals (hereinafter, digital I signal and digital Q). Signal) is generated.

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

The RF IC 221 is, for example, an RF analog IC, a high frequency IC, or both of them. The RF IC 221 includes a filter 222, a mixer 223, a preamplifier (PA) 224, a PLL (Phase Locked Loop) 242, a low noise amplifier (LNA), a balun 235, a mixer 233, and a filter 232. Some of these elements may be located on baseband IC211 or another IC. The filters 222 and 232 may be a band pass filter or a low pass filter. The RF IC 221 is coupled to the antenna 247 via a switch 245.

The filter 222 extracts a signal in a desired band from each of the analog I signal and the analog Q signal input from the DAC 216. The PLL 242 uses an oscillating signal input from the crystal oscillator 243, and divides or multiplies the oscillating signal, or both, to generate a signal having a constant frequency synchronized with the phase of the input signal. The PLL 242 includes a VCO (Voltage Controlled Oscillator), and obtains a signal having the constant frequency by performing feedback control using the VCO based on the 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 signal having a constant frequency supplied from the PLL 242. The preamplifier (PA) amplifies the analog I signal and analog Q signal of the radio frequency generated by the mixer 223 to the desired output power. The balun 225 is a converter for converting a balanced signal (differential signal) into an unbalanced signal (single-ended signal). The RF IC 221 handles balanced signals, but since the unbalanced signals are handled from the output of the RF IC 221 to the antenna 247, the balun 225 performs these signal conversions.

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

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

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

The LNA 234 in the RF IC 221 amplifies the signal received from the antenna 247 via the switch 245 to a level that can be demodulated while keeping the noise low. The balun 235 performs an unbalanced-equilibrium conversion of the signal amplified by the low noise amplifier (LNA) 234. The mixer 233 down-converts the received signal converted into the balanced signal by the balun 235 to the baseband using the signal of a constant frequency input from the PLL 242. More specifically, the mixer 233 has means for generating carriers that are 90 ° out of phase with each other based on the constant frequency signal input from the PLL 242, and the received signals converted by the balun 235 are 90 ° to each other. Orthogonal demodulation is performed by the out-of-phase carrier to generate an I (In-phase) signal having the same phase as the received signal and a Q (Quad-phase) signal having a phase delayed by 90 ° from the I (In-phase) signal. The filter 232 extracts a signal 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 the Q signal into a digital Q signal. In some cases, only one system of signals may be received without orthogonal demodulation.

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

(Fourth Embodiment)
23 (A) and 23 (B) are perspective views of the wireless communication terminal according to the fourth embodiment, respectively. The wireless communication terminal of FIG. 23 (A) is a notebook PC 301, and the wireless communication terminal of FIG. 23 (B) is a mobile terminal 321. Each corresponds to one form of a terminal (including a base station). The notebook PC 301 and the mobile terminal 321 are equipped with wireless communication devices 305 and 315, respectively. As the wireless communication devices 305 and 315, the wireless communication devices mounted on the terminals (including base stations) described above can be used. The wireless communication terminal equipped with the wireless communication device is not limited to a notebook PC or a mobile terminal. For example, TVs, digital cameras, wearable devices, tablets, smartphones, game devices, network storage devices, monitors, digital audio players, web cameras, video cameras, projects, navigation systems, external adapters, internal adapters, set-top boxes, gateways, etc. It can also be installed in printer servers, mobile access points, routers, enterprise / service provider access points, portable devices, handheld devices, automobiles, and the like.

Further, the wireless communication device mounted on the terminal (including the base station) can also be mounted on the memory card. FIG. 24 shows an example in which the wireless communication device is mounted on a memory card. The memory card 331 includes a wireless communication device 355 and a memory card main body 332. The memory card 331 utilizes a wireless communication device 335 for wireless communication with an external device (wireless communication terminal and / or base station, etc.). In addition, in FIG. 24, the description of other elements (for example, memory etc.) in the memory card 331 is omitted.

(Fifth Embodiment)
A fifth embodiment includes a bus, a processor unit, and an external interface unit in addition to the configuration of the wireless communication device according to any one of the above-described embodiments. The processor unit and the external interface unit are connected to the buffer via a bus. Firmware operates in the processor section. By including the firmware in the wireless communication device in this way, it is possible to easily change the function of the wireless communication device by rewriting the firmware. The processor unit on which the firmware operates may be a processor that performs processing of the communication processing device or control unit according to the present embodiment, or may be another processor that performs processing related to function expansion or modification of the processing. It is also good. The processor unit on which the firmware operates may be provided by the base station, the wireless communication terminal, or both of them according to the present embodiment. Alternatively, the processor unit may be provided with an integrated circuit in a wireless communication device mounted on a base station or an integrated circuit in a wireless communication device mounted on a wireless communication terminal.

(Sixth Embodiment)
The sixth embodiment includes a clock generation unit in addition to the configuration of the wireless communication device according to any one of the above-described embodiments. The clock generator generates a clock and outputs the clock from the output terminal to the outside of the wireless communication device. In this way, the clock generated inside the wireless communication device is output to the outside, and the host side is operated by the clock output to the outside, so that the host side and the wireless communication device side can be operated in synchronization with each other. It will be possible.

(7th Embodiment)
In the seventh embodiment, in addition to the configuration of the wireless communication device according to any one of the above-described embodiments, 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 controls to select the power supply to be supplied to the wireless communication device. In this way, by providing the wireless communication device with a power source, it is possible to perform a low power consumption operation in which the power source is controlled.

(8th Embodiment)
The eighth embodiment includes a SIM card in addition to the configuration of the wireless communication device according to any one of the above-described embodiments. The SIM card is connected to, for example, a control unit, a transmission unit, and a reception unit. As described above, by providing the SIM card in the wireless communication device, the authentication process can be easily performed.

(9th embodiment)
The ninth embodiment includes a moving image compression / decompression unit in addition to the configuration of the wireless communication device according to any one of the above-described embodiments. The moving image compression / decompression section is connected to the bus. As described above, by providing the moving image compression / decompression unit in the wireless communication device, it is possible to easily transmit the compressed moving image and decompress the received compressed moving image.

(10th Embodiment)
The tenth embodiment includes an LED unit in addition to the configuration of the wireless communication device according to any one of the above-described embodiments. The LED unit is connected to, for example, at least one of a control unit, a transmission unit, and a reception unit. By providing the LED unit in the wireless communication device in this way, it is possible to easily notify the user of the operating state of the wireless communication device.

(11th Embodiment)
The eleventh embodiment includes a vibrator unit in addition to the configuration of the wireless communication device according to any one of the above-described embodiments. The vibrator unit is connected to, for example, at least one of a control unit, a transmission unit, and a reception unit. By providing the vibrator unit in the wireless communication device in this way, it is possible to easily notify the user of the operating state of the wireless communication device.

(12th Embodiment)
A twelfth embodiment includes a display in addition to the configuration of the wireless communication device (the wireless communication device of the base station, the wireless communication device of the wireless communication terminal, or both) according to any one of the above-described embodiments. The display may be connected to the control unit of the wireless communication device via a bus (not shown). By providing the display in this way and displaying the operating state of the wireless communication device on the display, it is possible to easily notify the user of the operating state of the wireless communication device.

(13th Embodiment)
In this embodiment, [1] a frame type in a wireless communication system, [2] a method of disconnecting a connection between wireless communication devices, [3] an access method of a wireless LAN system, and [4] a frame interval of a wireless LAN will be described.
[1] Frame type in communication system Generally, as described above, the frames handled on the wireless access protocol in a wireless communication system are roughly classified into three frames: a data frame, a management frame, and a control frame. It can be divided into types. These types are usually indicated by a header portion commonly provided between frames. As a display method of the frame type, one field may be capable of distinguishing three types, or a combination of two fields may be used to distinguish between the three types. In the IEEE802.11 standard, the frame type is identified by two fields, Type and Subtype in the Frame Control field in the frame header part of the MAC frame. The data frame, the management frame, and the control frame are roughly classified in the Type field, and the subtypes in the roughly classified frames, for example, the Beacon frame in the management frame, are identified in the Subtype field.

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

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

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

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

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

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

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

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

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

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

[4] Wireless LAN frame interval The 802.11 wireless LAN frame interval will be described. The frame intervals used in the IEEE802.11 wireless LAN are distributed codeintion interface interface (DIFS), arbitration interframe space (AIFS), point codeination interface , Reduced interframe space (RIFS) and the like.

The definition of the frame interval is defined in the IEEE 802.11 wireless LAN as a continuous period in which the carrier sense idle should be confirmed and opened before transmission, and the exact period from the previous frame is not discussed. Therefore, in the description of the 802.11 wireless LAN system here, the definition is followed. In the 802.11 wireless LAN, the time to wait for random access based on CSMA / CA is the sum of the fixed time and the random time, and it can be said that this definition is used to clarify the fixed time.

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

Since the operations related to DIFS and AIFS are similar, they will be described mainly using AIFS below. In the 802.11 wireless LAN, access control including the start of frame exchange is performed at the MAC layer. Further, when QoS (Quality of Service) is supported when the data is passed from the upper layer, the traffic type is notified together with the data, and the data is classified into the priority at the time of access based on the traffic type. This access class is called an access category (AC). Therefore, the AIFS value is provided for each access category.

PIFS is a frame interval for allowing access with priority over other competing wireless communication devices, and has a shorter period than either DIFS or AIFS value. 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. EIFS is a frame interval that is activated when frame reception fails (it is determined that the received frame is an error).

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

Here, FIG. 25 shows an example of frame exchange during a conflict period based on random access in the 802.11 wireless LAN.

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

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

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

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

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

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

Further, in the present specification, "at least one of a, b and c" is not only a combination of a, b, c, ab, ac, bc and abc, but also aa. , Abb, a-ab-bc-c, etc. It is an expression including a plurality of combinations of the same elements. Further, it is an expression that covers a configuration including elements other than a, b, and c, such as a combination of abcd.

The frame described in each embodiment may refer not only to a frame called a frame in the IEEE802.11 standard, but also to a packet such as a Null Data Packet. When a base station expresses that it transmits or receives a plurality of frames or a plurality of X-th frames, these frames or the X-th frames may be the same (for example, the same type or the same contents) or different. .. Any value can be entered in X depending on the situation. Further, the plurality of frames or the plurality of X-th frames may be transmitted or received not only at the same time but also at different timings in time. Further, when expressing that the first frame, the second frame, etc. are transmitted or received at different time points, the expressions of the first, second, etc. are merely expressions for distinguishing the frames, and these expressions are used. There is no difference in the type and content of the frame.

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

The following is a description of the scope of claims at the time of filing the original application.
[1]
Set at least one of the first transmission prohibition period for the first network to which the own device belongs and the second transmission prohibition period for the second network.
When the first frame addressed to another device is received while the first transmission prohibition period is not set and the second transmission prohibition period is set, the reception level of the first frame is set. A wireless communication device including a control unit that determines the state of a wireless medium by comparing with a threshold value corresponding to the network of the source of the first frame among the first network and the second network.
[2]
When the source of the first frame belongs to the second network and it is determined that the state of the radio medium is idle, the second frame is transmitted even within the second transmission prohibition period. The wireless communication device according to [1], which comprises a transmission unit for transmission.
[3]
Equipped with a receiver that receives the third frame addressed to other devices
The control unit sets the first transmission prohibition period when the source of the third frame belongs to the first network, and the second transmission when the source belongs to the second network. The wireless communication device according to any one of [1] and [2] for which a prohibition period is set.
[4]
The control unit sets the first transmission prohibition period based on the third frame, and when the fifth frame addressed to another device is received after a certain period of time from the reception of the third frame, the fifth frame is received. The wireless communication device according to [3], wherein the first transmission prohibition period is updated or additionally set based on a frame.
[5]
When the network of the source of the third frame cannot be determined, the control unit sets the second transmission prohibition period.
After the second transmission prohibition period is set based on the third frame, the receiving unit receives the sixth frame addressed to another device whose transmission source belongs to the second network.
If neither the receiving address nor the source address of the third frame matches one of the source address and the receiving address of the sixth frame, the control unit determines that the radio medium is busy. The wireless communication device according to any one of [3] to [4].
[6]
The control unit uses the first threshold value as the threshold value when the source of the first frame belongs to the first network, and the second threshold value larger than the first threshold value when the source belongs to the second network. The wireless communication device according to any one of [1] to [5], wherein the state of the wireless medium is determined by using.
[7]
The control unit holds a reception address of one or more frames destined for another device that has been received from the first network so far.
When the reception address of the first frame matches any of the reception addresses held by the control unit, the control unit determines that the source of the first frame belongs to the first network []. 1] The wireless communication device according to any one of [6].
[8]
The control unit holds a reception address of one or more frames destined for another device that has been received from the first network so far.
When the reception address of the third frame matches any of the reception addresses held by the control unit, the control unit determines that the source of the third frame belongs to the first network []. 3] The wireless communication device according to any one of [5].
[9]
The header added to the first frame contains the identification information of the network to which the first frame is transmitted.
The wireless communication device according to any one of [1] to [8], wherein the control unit determines the network of the source of the first frame based on the identification information.
[10]
The header added to the third frame contains the identification information of the network to which the third frame is transmitted.
The wireless communication device according to any one of [3] to [5], wherein the control unit determines the network of the source of the third frame based on the identification information.
[11]
The wireless communication device according to any one of [1] to [10], which comprises at least one antenna.
[12]
With at least one antenna,
A receiver that is coupled to the antenna and receives a frame,
A transmitter that is coupled to the antenna and transmits a frame,
A communication processing unit coupled to the receiving unit and the transmitting unit,
A network processing unit that is coupled to the communication processing unit, transmits data to the communication processing unit, and receives data from another device.
A memory that is coupled to the network processing unit and caches the first data,
Equipped with
The communication processing unit sets at least one of a first transmission prohibition period for the first network to which the own device belongs and a second transmission prohibition period for the second network, and the first transmission prohibition period is not set. When the first frame addressed to another device is received while the second transmission prohibition period is set, the reception level of the first frame is set to the first of the first network and the second network. The state of the radio medium is determined by comparing with the threshold value according to the network of the source of the frame.
The transmitting unit transmits a second frame when the state of the wireless medium is determined to be idle.
The second frame includes the first data cached in the memory or information based on the first data.
Wireless communication terminal.
[13]
Set at least one of the first transmission prohibition period for the first network to which the own device belongs and the second transmission prohibition period for the second network.
When the first frame addressed to another device is received while the first transmission prohibition period is not set and the second transmission prohibition period is set, the reception level of the first frame is set. A wireless communication method for determining the state of a wireless medium by comparing with a threshold value corresponding to the network of the source of the first frame among the first network and the second network.

1A, 1B, 2A, 2B: Wireless communication terminals 11, 21: Base station (access point)
101, 201: Control unit 102, 202: Transmission unit 103, 203: Reception unit 104, 204: Buffers 12A to 12D: Antenna 211: Baseband IC
213: Memory 214: Host interface 215: CPU
216: DAC
217: ADC
221: RF IC
222: 232: Filter 223, 233: Mixer 224, 234: Amplifier 225, 235: Balun 242: PLL
243: Crystal oscillator 247: Antenna 245: Switch 148: Wireless LAN module 149: Host system 301: Notebook PC
305, 315, 355: Wireless communication device 321: Mobile terminal 331: Memory card 332: Memory card body 61, 64, 66: Intra-BSS NAV
62, 65, 67, 68: Regular NAV

Claims (4)

A receiver that receives the first frame addressed to another device,
When the source of the first frame belongs to the first network to which the own device belongs, the first transmission prohibition period for the first network is set, and the source of the first frame belongs to the second network. If so, set the second transmission prohibition period for the second network.
In a state where the first transmission prohibition period is not set and the second transmission prohibition period is set, the second frame addressed to another device whose reception level is equal to or higher than the first threshold value is received during the carrier sense. In that case, the network of the source of the second frame is determined based on the header of the second frame, and if the network of the source of the second frame is the first network, the reception of the second frame is received. The state of the wireless medium is determined by comparing the level with the first threshold value, and when the source network of the second frame is the second network, the reception level of the second frame is set from the first threshold value. A control unit that determines the state of the radio medium by comparing with a large second threshold value.
Equipped with
The header added to the first frame contains the identification information of the network to which the first frame is transmitted.
The control unit is a wireless communication device that determines the network of the source of the first frame based on the identification information. The header of the first frame is a header of a physical packet including the first frame.
The wireless communication device according to claim 1, wherein the identification information is stored in the header of the physical packet. The wireless communication device according to claim 1 or 2, comprising at least one antenna. A wireless communication method executed by a wireless communication device.
Receive the first frame addressed to another device and
When the source of the first frame belongs to the first network to which the wireless communication device belongs, the first transmission prohibition period for the first network is set, and the source of the first frame is the second network. If it belongs to, set the second transmission prohibition period for the second network, and
In a state where the first transmission prohibition period is not set and the second transmission prohibition period is set, the second frame addressed to another device whose reception level is equal to or higher than the first threshold value is received during the carrier sense. In that case, the network of the source of the second frame is determined based on the header of the second frame, and if the network of the source of the second frame is the first network, the reception of the second frame is received. The state of the wireless medium is determined by comparing the level with the first threshold value, and when the source network of the second frame is the second network, the reception level of the second frame is set from the first threshold value. By comparing with a large second threshold value, the state of the radio medium is determined.
The header added to the first frame contains the identification information of the network to which the first frame is transmitted.
A wireless communication method for determining the network of the source of the first frame based on the identification information.

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