Wireless communication device and wireless communication method

Abstract

In the present invention, control information includes information indicating whether or not a beam tracking signal is included in a PE field 802. When the beam tracking signal for beam tracking is included in the PE field 802, N beam tracking signals 803-1 to 803-N are inserted therein, and transmission beam forming using different transmission weights is performed. The duration of the PE field is set on the basis of different tables depending on whether the beam tracking signal is not included or is included in the PE field.

Description

Wireless Communication Apparatus and Wireless Communication Method

[0001] The present invention relates to a wireless communication apparatus and a wireless communication method.

[0002] At the Institute of Electrical and Electronics Engineers Inc. (IEEE), work to establish a new standard for IEEE 802.11, which is a wireless local area network (wireless LAN) standard, has been continuously carried out to achieve higher efficiency, higher communication speed, and improved frequency utilization efficiency of wireless LAN systems.

[0003] In the specifications of the IEEE 802.11 series, a wireless communication apparatus in a wireless LAN system is referred to as a station (STA: STAtion). An STA that connects a plurality of other STAs and provides network services is referred to as an access point station (AP STA: Access Point STA), and an STA that connects to an AP STA and receives network services is referred to as a non-access point station (non-AP STA). Hereinafter, an AP STA is also referred to as an access point (AP), an access point apparatus, or a base station apparatus, and a non-AP STA is also referred to as a terminal, a user terminal, a terminal apparatus, or a user terminal apparatus.

[0004] Furthermore, at the Integrated mmWave Study Group (IMMW SG) of IEEE 802.11, a policy to reuse the single-user transmission frame format using Orthogonal Frequency Division Multiplexing (OFDM) specified in standards such as IEEE 802.11ac, IEEE 802.11ax, and IEEE 802.11be for frequency bands below 7 GHz (sub-7 GHz) has been determined for the development of a next-generation millimeter-wave band wireless communication standard (Non-Patent Document 1). Based on this policy, Task Group bq (TGbq), which develops the next-generation millimeter-wave band wireless communication standard, has been established and discussions have been started.

[0005] IEEE P802.11bq Draft PAR

[0006] In wireless communication, a challenge when using beamforming for transmission and reception is that the time fluctuations in the propagation path can lead to a degradation of communication quality or link disconnection.

[0007] A wireless communication device and wireless communication method according to one aspect of the present invention for solving the above-mentioned problems are as follows.

[0008] (1) That is, a first wireless communication device according to one aspect of the present invention comprises a wireless transmission unit and a control unit, wherein the control unit includes in the control field of the transmission frame first information indicating whether or not the packet extension field of the transmission frame includes a beam tracking signal, the wireless transmission unit transmits the transmission frame to a second wireless communication device, and the duration of the packet extension field is set by the first information and a table, a calculation formula or both.

[0009] (2) Furthermore, the first wireless communication device according to one aspect of the present invention has a table, a calculation formula, or both used when the first information indicates that the packet extension field does not contain a beam tracking signal, and a table, a calculation formula, or both used when the first information indicates that the packet extension field contains a beam tracking signal.

[0010] (3) In addition, in the first wireless communication device according to one aspect of the present invention, the beam tracking signal includes a plurality of subfields, and each of the plurality of subfields is beamformed.

[0011] (4) In addition, in the first wireless communication device according to one aspect of the present invention, the modulation symbol of the beam tracking signal is generated using phase shift modulation, regardless of the modulation method of the data field of the transmission frame.

[0012] (5) A first wireless communication device according to one aspect of the present invention further comprises a wireless receiving unit, the wireless receiving unit receiving a frame from the second wireless communication device that includes a second information representing an index indicating any one of the plurality of subfields.

[0013] (6) A second wireless communication device according to one aspect of the present invention comprises a wireless receiving unit, a wireless transmitting unit, and a control unit, wherein the wireless receiving unit receives a frame transmitted by the first wireless communication device, and the control field of the received frame contains first information indicating whether or not the packet extension field of the received frame contains a beam tracking signal, and the control unit identifies the duration of the packet extension field based on the first information and a table, a calculation formula, or both.

[0014] (7) In addition, in a second wireless communication device according to one aspect of the present invention, the control unit selects one of a plurality of subfields included in the beam tracking signal when the first information indicates that the packet extension field includes the beam tracking signal, and the wireless transmission unit transmits a frame to the first wireless communication device that includes second information indicating the index of the selected subfield.

[0015] (8) In addition, in a second wireless communication device according to one aspect of the present invention, the wireless receiving unit measures the received power of each of the plurality of subfields included in the beam tracking signal, and the control unit selects the subfield with the maximum received power from among the plurality of subfields.

[0016] (9) Another aspect of the present invention is a wireless communication method in a first wireless communication device, comprising the steps of: including in the control field of a transmission frame a first information indicating whether or not the packet extension field of the transmission frame includes a beam tracking signal; and transmitting the transmission frame to a second wireless communication device, wherein the duration of the packet extension field is set by the first information and a table, a calculation formula, or both.

[0017] According to the wireless communication device and wireless communication method of the present invention, when transmitting and receiving using beamforming, it becomes possible to perform beam tracking in a timely manner, thereby reducing deterioration of communication quality and link disconnection.

[0018] This figure shows an example configuration of a wireless communication system according to one aspect of the present invention. This figure shows an example of a PHY layer frame configuration related to a wireless LAN system. This figure shows an example of a MAC layer frame configuration related to a wireless LAN system. This block diagram shows an example configuration of a wireless communication device according to one aspect of the present invention. This figure shows an example of a process for adding a PE field in a wireless communication device according to one aspect of the present invention. This figure shows an example of a table of PE field durations when beam tracking signals are not included in a wireless communication system according to one aspect of the present invention. This figure shows an example of a table of PE field durations when beam tracking signals are not included in a wireless communication system according to one aspect of the present invention. This figure shows an example of a PPDU with beam tracking signals inserted into the PE field in a wireless communication system according to one aspect of the present invention. This figure shows an example of a table of PE field durations when beam tracking signals are included in a wireless communication system according to one aspect of the present invention. This figure shows an example of a table of PE field durations when beam tracking signals are included in a wireless communication system according to one aspect of the present invention.

[0019] The wireless communication system in this embodiment comprises an access point device (AP STA, also referred to as a base station device) and a plurality of terminal devices (also referred to as non-AP STAs). Furthermore, the wireless communication system and network composed of the access point device and the terminal devices connected to it are referred to as a BSS (Basic Service Set). The terminal devices in this embodiment may also have the functions of an access point device. Similarly, the access point device in this embodiment may also have the functions of a terminal device. Hereinafter, when simply referred to as STA or wireless communication device, it refers to both the access point device and the terminal devices.

[0020] The access point device and terminal device within the BSS shall perform wireless communication based on CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). In this embodiment, the infrastructure mode in which the access point device performs wireless communication with multiple terminal devices is targeted, but the method of this embodiment can also be implemented in ad-hoc mode in which terminal devices perform wireless communication directly with each other. In ad-hoc mode, one terminal device acts as a substitute for the access point device and forms the BSS. The BSS in ad-hoc mode is also called IBSS (Independent Basic Service Set). Hereafter, the terminal device that forms the IBSS in ad-hoc mode can also be considered as the access point device.

[0021] Figure 1 shows an example of a wireless communication system according to this embodiment. In Figure 1, a wireless communication system 100-1 (also referred to as BSS 100-1), which consists of an access point (AP) device 101-1 and a terminal device 102-1, and a wireless communication system 100-2 (also referred to as BSS 100-2), which consists of an access point (AP) device 101-2 and a terminal device 102-2, are shown as an example of an environment in which part or all of their communication areas overlap. In this embodiment, the case in which wireless frames transmitted by each wireless communication device are received by all other wireless communication devices (observable at a predetermined reception power or higher) is described as an example. Other BSSs whose communication areas overlap in this way are called OBSS (Overlapping BSS). In the example of the wireless communication system in Figure 1, BSS 100-1 and BSS 100-2 recognize each other as OBSS. Although wireless communication systems 100-1 and 100-2 form different BSSs, this does not necessarily mean that they have different ESSs (Extended Service Sets) that represent the service sets forming the LAN. In other words, wireless communication devices belonging to the same ESS can be considered to belong to the same network from the upper layer. Furthermore, BSSs can be combined via a DS (Distribution System) to form an ESS. In addition, each of wireless communication systems 100-1 and 100-2 may also be equipped with multiple terminal devices.

[0022] In IEEE 802.11 wireless communication systems, each wireless communication device can transmit multiple types of frames that share a common frame format. Frames are defined in the Physical (PHY) layer, the Medium Access Control (MAC) layer, and the Logical Link Control (LLC) layer, respectively.

[0023] A frame in the PHY layer is called a Physical Protocol Data Unit (PPDU: PHY Protocol Data Unit, or Physical Layer Frame). Hereafter, the PHY layer frame will also be referred to as a wireless frame. Unless otherwise specified, the term "frame" will refer to a wireless frame. A PPDU consists of a training field (TF) used to assist in signal detection, propagation path estimation, and demodulation processing in the physical layer, a signal field (SIG) containing information for signal processing in the physical layer, and a Physical Service Data Unit (PSDU: PHY Service Data Unit), which is a data unit processed in the physical layer. A PSDU can also consist of an aggregated MPDU (A-MPDU), which is a combination of multiple MAC Protocol Data Units (MPDU: MAC Layer Frames), which are retransmission units in the wireless section.

[0024] Figure 2 shows an example of a PHY layer frame and PPDU configuration in a wireless LAN system. Figure 2 shows an example of a PPDU configuration in each of the IEEE 802.11n (HT: High Throughput), IEEE 802.11ac (VHT: Very High Throughput), IEEE 802.11ax (HE: High Efficiency), and IEEE 802.11be (EHT: Extremely High Throughput) standards. A PPDU includes multiple short training fields (STFs) used for signal detection and synchronization, and long training fields (LTFs) used for acquiring channel information for data demodulation. STFs are classified into L-STF (non-HT Short Training Field), HT-STF (High Throughput Short Training Field), VHT-STF (Very High Throughput Short Training Field), HE-STF (High Efficiency Short Training Field), EHT-STF (Extremely High Throughput Short Training Field), etc., depending on the corresponding standard. Similarly, LTFs are classified into L-LTF, HT-LTF, VHT-LTF, HE-LTF, EHT-LTF, etc., depending on the corresponding standard. PPDUs compliant with standards prior to IEEE 802.11n are also referred to as non-HT PPDUs.

[0025] Similarly, the SIGNAL field included in the PPDU is classified into L-SIG, HT-SIG, VHT-SIG, HE-SIG, EHT-SIG, etc., depending on the corresponding standard. VHT-SIG is further classified into VHT-SIG-A1, VHT-SIG-A2, and VHT-SIG-B. Similarly, HE-SIG is classified into HE-SIG-A1 to 4 and HE-SIG-B. As shown in Figure 2, the L-SIG field includes multiple subfields such as RATE and LENGTH. The LENGTH subfield of the L-SIG field indicates information about the length of the PPDU, such as the number of octets and the duration. In addition, a U-SIG (Universal SIG) field containing additional control information may be included in anticipation of specification updates within the same standard. Furthermore, the RL-SIG field included in the PPDUs (HE PPDU and EHT PPDU) of the IEEE 802.11ax and IEEE 802.11be standards is a repetition of the L-SIG field, and can be used to distinguish HE PPDUs and EHT PPDUs from PPDUs of earlier standards.

[0026] Furthermore, the PPDU may include information that identifies the BSS that originated from the frame (hereinafter also referred to as BSS identification information). This BSS identification information may be, for example, the BSS's SSID (Service Set Identifier) ​​or the MAC address of the BSS's access point device. Alternatively, the BSS identification information may be a value unique to the BSS other than the SSID or MAC address (e.g., BSS Color). Information indicating the BSS Color may be included in HE-SIG-A or U-SIG, etc.

[0027] In PPDUs following the IEEE 802.11ax standard, a packet extension field (PE field) may be added after the Data field to allow time for processing the received PPDU.

[0028] Figure 3 shows an example of an MPDU configuration, which is a MAC layer frame in a wireless LAN system. An MPDU consists of a MAC header containing information for signal processing at the MAC layer, a MAC Service Data Unit (MSDU) or frame body, which is a data unit input to and processed at the MAC layer, and a Frame Check Sequence (FCS) field that checks whether the MAC layer frame is error-free. Multiple MSDUs can also be aggregated as an Aggregated MSDU (A-MSDU) and included in the frame body.

[0029] Each wireless communication device can recognize the frame type and subframe type of a received MAC layer frame by reading the contents of the frame control field included in the MAC header. MAC layer frame types are broadly classified into three categories: management frames that manage the connection status between wireless communication devices, control frames that manage the communication status between wireless communication devices, and data frames that contain the actual transmission data. Each of these is further classified into multiple subframe types. Control frames include acknowledgment (Ack or ACK) frames, block acknowledgment (BA or BlockAck) frames, request to send (RTS) frames, and clear to send (CTS) frames. BA can issue acknowledgments (reception completion notifications) to multiple MPDUs. Management frames include beacon frames, probe request frames, probe response frames, authentication frames, association request frames, and association response frames. Data frames include data frames, polling (CF-Poll) frames, and others.

[0030] The MAC header also includes a Duration / ID field. For some frame types, the Duration / ID field indicates the Association Identifier (AID) of the frame's sender. For other frame types, it can indicate the duration of the wireless medium's possession due to the frame's transmission, or the duration of the wireless medium's possession due to the transmission of the frame and the associated series of frames. When indicating a duration, the Duration / ID field is also simply referred to as the Duration field.

[0031] Furthermore, the MAC header can contain up to four address fields indicating the MAC address. Depending on the frame type, the address fields at their respective positions display the BSS identifier (BSSID), source address (SA), destination address (DA), transmitting address (TA), and receiving address (RA). Hereafter, the various address information shown in the MAC header's address fields will be collectively referred to as address information or MAC address information.

[0032] A beacon frame includes fields such as the beacon transmission interval and the SSID, which is a string used to identify the BSS. Access point devices can periodically broadcast beacon frames within the BSS, and terminal devices can recognize nearby access point devices by receiving these beacon frames. Recognizing an access point device based on beacon frames broadcast by the access point device is called passive scanning. On the other hand, searching for an access point device by broadcasting a probe request frame within the BSS is called active scanning. An access point device can send a probe response frame in response to the probe request frame, and the content of the probe response frame is the same as the content of the beacon frame.

[0033] After recognizing the access point device, the terminal device initiates a connection process to the access point device. The connection process is classified into authentication and association procedures. The terminal device sends an authentication request frame to the access point device it wishes to connect to. Upon receiving the authentication request frame, the access point device sends an authentication response frame to the terminal device containing a status code indicating whether authentication to the terminal device was granted or denied. By reading the status code contained in the authentication response frame, the terminal device can determine whether its authentication request to the access point device has been authorized. The access point device and the terminal device can exchange authentication request frames and authentication response frames (collectively referred to as authentication frames) multiple times.

[0034] Following the authentication process, the terminal device sends a connection request frame to the access point device to initiate the connection procedure. Upon receiving the connection request frame, the access point device determines whether to allow the terminal device to connect and sends a connection response frame to notify the access point of this decision. The connection response frame includes a status code indicating whether the connection process was successful or not, as well as an AID to identify the terminal device. The access point device can manage multiple terminal devices by assigning a different AID to each terminal device for which it has granted connection permission.

[0035] After the connection process is completed, the access point device and the terminal device perform the actual data transmission. In IEEE 802.11 systems, Distributed Coordination Function (DCF), Point Coordination Function (PCF), and the extended Hybrid Coordination Function (HCF) are defined as media access methods. For HCF, Enhanced Distributed Channel Access (EDCA) and HCF Controlled Channel Access (HCCA) are defined as specific implementation methods.

[0036] This section describes an example of how a wireless communication device operates when transmitting a wireless frame based on DCF (Distributed Carrier Sense). In DCF, a wireless communication device performs carrier sense (CS) to check the usage status of the wireless channels around it before communication. For example, if a wireless communication device intending to transmit a frame receives a signal with a received power higher than a predetermined Clear Channel Assessment level (CCA level) on the wireless channel during the carrier sense period performed prior to transmission, it will postpone transmitting the frame on that wireless channel. In the following, the state in which a signal with a received power of CCA level or higher is detected on the wireless channel will be referred to as the wireless medium being busy, and the state in which no signal with a received power of CCA level or higher is detected will be referred to as the wireless medium being idle. Carrier sense performed by each wireless communication device based on the power level of the signal actually received in this manner is called physical carrier sense (physical CS). The CCA level is also called the carrier sense level (CS level) or the CCA threshold (CCAT). Furthermore, if the wireless communication device detects a signal with a received power of CCA level or higher, it will start demodulating the signal at least in the PHY layer.

[0037] A wireless communication device performs carrier sensing for a period of time corresponding to the frame type and subframe type being transmitted, using an Inter-Frame Space (IFS) set accordingly, to determine whether the wireless channel is busy or idle. In IEEE 802.11 systems, several IFSs with different durations are defined, including a Short IFS (SIFS) used for frames with the highest priority, a Polling IFS (PIFS: PCF IFS) used for frames with relatively high priority, and a Distributed Arbitration IFS (DIFS: DCF IFS) used for frames with low priority. When transmitting data frames using DCF, the wireless communication device uses the DIFS.

[0038] After waiting for the DIFS period, the radio communication device waits for an additional random backoff time to prevent frame collisions. In IEEE 802.11 systems, a random backoff time based on the Contention Window (CW) is used. CSMA / CA assumes that a frame transmitted by one transmitting station is received by a receiving station without interference from other transmitting stations. Therefore, if multiple transmitting stations transmit frames at the same time, the frames may collide, and the receiving station may not be able to receive them correctly. To avoid this, each transmitting station waits for a randomly set time before starting to transmit, thus preventing frame collisions. When the radio communication device determines through carrier sense that the radio channel is idle, it starts counting down the backoff counter, which is set based on CW. Only when the backoff counter reaches zero does it acquire a transmission opportunity (TXOP) and become able to transmit a frame. The radio communication device also continues carrier sense during the backoff counter countdown, and stops counting down the backoff counter if it determines that the radio channel has become busy again. Then, if the radio channel becomes idle again, the radio communication device waits for the same period as the previous IFS, and then resumes counting down the remaining count of the backoff counter. The procedure for acquiring a TXOP using the backoff counter described above is also called the backoff procedure.

[0039] The receiving station, a wireless communication device, receives a frame, reads information such as the SIGNAL field according to the frame's corresponding standard, and demodulates the received frame. The wireless communication device can then identify whether the frame is addressed to itself by reading the MAC header of the demodulated signal. The wireless communication device can also determine the destination of the frame based on information contained in the SIGNAL field, such as the group identification number (GID: Group Identifier, Group ID) contained in VHT-SIG-A.

[0040] If a radio communication device determines that a received frame is intended for itself and has successfully demodulated the frame without error, it must transmit an Ack frame to the transmitting radio communication device to indicate that the frame was received correctly. The Ack frame is one of the highest-priority frames and is transmitted only during the SIFS period (without taking a random backoff time). The transmitting radio communication device terminates the communication series upon receiving the Ack frame transmitted from the receiving radio communication device. If the receiving radio communication device fails to receive the frame correctly, it will not transmit an Ack frame. Therefore, if the transmitting radio communication device does not receive an Ack frame from the receiving station within a certain period after transmitting the frame (SIFS + Ack frame length), it determines that the communication has failed and terminates the communication. Thus, the termination of a single communication (also called a burst) in an IEEE 802.11 system is always determined by whether or not an Ack frame has been received, except in special cases such as the transmission of broadcast signals like beacon frames or when fragmentation is used to divide the transmitted data.

[0041] Next, we will explain an example of how an access point device operates when transmitting signals to terminal devices based on PCF. Unlike DCF, where each device autonomously acquires transmission rights by performing carrier sensing, in PCF, a control station called a point coordinator controls the transmission rights of each device within the BSS. Generally, the access point device acts as the point coordinator and acquires transmission rights for the terminal devices within the BSS.

[0042] The PCF communication period includes a Contention Free Period (CFP) and a Contention Period (CP). During the CP, communication is conducted based on the DCF described above, and the point coordinator controls the transmission rights during the CFP period. The access point device, acting as the point coordinator, broadcasts a beacon frame containing information such as the maximum duration of the CFP within the BSS prior to PCF communication. The beacon frame broadcast at the start of PCF transmission is transmitted using PIFS and is transmitted without a backoff procedure. The terminal device that receives the beacon frame sets the CFP Max duration value contained in the beacon frame to the Network Allocation Vector (NAV), which maintains a period during which it does not transmit frames to the wireless medium. From this point forward, until the duration set in the NAV expires, or a signal (e.g., a data frame containing CF-End) indicating the end of CFP is received within the BSS, each terminal device can only acquire transmission rights if it receives a signal (e.g., a data frame containing CF-Pol) from the point coordinator signaling the acquisition of transmission rights for its own device. Note that, since packet collisions do not occur within the same BSS during the CFP period, each terminal device does not take the random backoff time used in DCF.

[0043] Furthermore, TXOP in EDCA, which is a data transmission method different from DCF, will also be described. The IEEE 802.11e standard relates to EDCA and specifies TXOP from the perspective of QoS (Quality of Service) guarantee for various services such as video transmission and VoIP (Voice over IP). Services are broadly classified into four access categories: VO (VOice), VI (VIdeo), BE (Best Effort), and BK (BacK ground). In general, in order from highest priority to lowest, the order is VO, VI, BE, BK. Each access category has parameters of CW minimum CWmin, CW maximum CWmax, AIFS (Arbitration IFS), which is a type of IFS, and TXOP limit which is the upper limit of transmission opportunity, and the values are set so as to differentiate the priority. For example, by setting relatively smaller values for CWmin, CWmax and AIFS of VO, which is the highest priority for voice transmission, compared with other access categories, data transmission prioritized over other access categories can be achieved. For example, in VI where the amount of transmission data is relatively large for video transmission, by setting a large TXOP limit, it is possible to obtain a longer transmission opportunity than other access categories. In this way, for the purpose of QoS guarantee according to various services, the values of the four parameters for each access category are adjusted.

[0044] Furthermore, as QoS settings for MSDU input from an upper layer to the MAC layer, TID (Traffic IDentifier) can be used. Eight of the TIDs can identify traffic categories (TC), and the remaining eight can identify parameterized traffic streams (TS).

[0045] Figure 4 is a diagram showing an example configuration of a wireless communication apparatus 400 according to the present embodiment. The configuration example of the wireless communication apparatus 400 shown in Figure 4 is a common configuration for the access point apparatuses 101-1 and 101-2, and the terminal apparatuses 102-1 and 102-2 in Figure 1.

[0046] The wireless communication device 400 is configured to include an upper layer unit (upper layer step) 401, a communication control unit (communication control step) 402, a wireless transmission unit (wireless transmission step) 403, a wireless reception unit (wireless reception step) 404, a carrier sense unit (carrier sense step) 405, and an antenna unit 406.

[0047] The upper layer unit 401 may implement some or all functions of layers above the MAC layer, for example, and perform processing. Note that the function of the upper layer unit 401 is not limited to this, and for example, it may further include some functions of the MAC layer.

[0048] The communication control unit 402 generates MPDUs of control frames and management frames, outputs them to the wireless transmission unit 403, and instructs transmission. Further, the communication control unit 402 uses a data unit (MSDU) input from the upper layer unit 401 as a frame body, and includes address information such as the BSSID of the BSS to which the wireless communication device 400 belongs, a source address, a destination address, a transmission address, and a reception address, QoS control information related to the MSDU, a MAC header including fields such as a duration, and an FCS (Frame Check Sequence) for error detection to generate an MPDU of a data frame, outputs it to the wireless transmission unit 403, and instructs transmission. The duration can be set to the duration of wireless medium occupancy caused by the transmission of the frame, the duration of wireless medium occupancy caused by the transmission of the frame and a series of associated frame exchanges, or the duration of a TXOP to be secured. Note that the communication control unit 402 may output an A-MPDU obtained by aggregating a plurality of MPDUs to the wireless transmission unit 403.

[0049] A frame transmission instruction to the wireless transmission unit 403 may be executed after the carrier sense result obtained by the carrier sense unit 405 indicates an idle state and a TXOP is obtained based on a backoff procedure. Note that for frames that can be transmitted without carrier sense, such as an Ack frame for a received frame and a response frame for a frame addressed to the own device from a TXOP holder, the above carrier sense and backoff procedures can be omitted.

[0050] Furthermore, the communication control unit 402 processes the received MPDU input from the wireless receiver unit 404. The communication control unit 402 performs a Cyclic Redundancy Check (CRC) on the received MPDU and compares it with the value of the FCS field to confirm whether the MPDU is correct. If the communication control unit 402 confirms that the MPDU is correct, it extracts the MAC header of the MPDU and identifies the frame type and subframe type from the frame control field. Based on the identified frame type and subframe type, the communication control unit 402 extracts the remaining fields of the MAC header and obtains information such as duration information, address information, and QoS control information indicated in each field. Note that an A-MPDU may also be input from the wireless receiver unit 404, in which case the wireless control unit 402 separates the A-MPDU into individual MPDUs and performs the above reception processing.

[0051] The communication control unit 402 identifies from the acquired address information whether the received MPDU is addressed to the local device (including multicast and broadcast messages that include the local device), and whether it is a frame within the BSS to which the local device belongs (referred to as an intra-BSS frame) or a frame from another BSS (referred to as an inter-BSS frame). The communication control unit 402 inputs the address information, the identification result of whether or not it is a frame within the BSS, and the duration information to the carrier sense unit 405. The communication control unit 402 also identifies that the received MPDU is addressed to the local device, and if the MPDU includes a frame body, i.e., an MSDU, it outputs the MSDU to the upper layer unit 401. The communication control unit 402 may also output to the upper layer unit 401 information such as the address information and QoS control information acquired along with the MSDU.

[0052] The wireless transmission unit 403 takes the MPDU or A-MPDU input from the communication control unit 402 as a PSDU, and generates a PPDU by adding a training field and a SIGNAL field to the PSDU. For example, in the case of a PPDU compliant with the IEEE 802.11be standard, L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, EHT-SIG, EHT-STF, and EHT-LTF are added before the PSDU to generate the PPDU. Furthermore, the wireless transmission unit 403 may add a PE field to the end of the PPDU as needed.

[0053] The wireless transmission unit 403 generates a wireless signal by performing processes such as error correction coding, digital modulation, mapping, frequency-time conversion, digital-to-analog conversion, filtering, and upconversion to radio frequency (RF) on the generated PPDU, and transmits it from the antenna unit 406 at the transmission timing instructed by the communication control unit 402.

[0054] The wireless receiver 404 performs down-conversion on the wireless signal received by the antenna 406, and processes such as filtering and analog-to-digital conversion to obtain a digital received signal. If the wireless receiver 404 successfully detects L-STF and L-LTF from the received signal and synchronizes with the received frame, it can further perform time-frequency conversion, demapping, digital demodulation, error correction decoding, etc. on the obtained digital received signal to acquire the received PPDU. The wireless receiver 404 outputs the acquired PPDU to the communication control unit 402. The wireless receiver 404 may interrupt the acquisition of the frame if it fails to acquire the L-SIG field, that is, if the parity check of the L-SIG field is unsuccessful. Furthermore, if a value specific to a BSS, such as BSS Color, is acquired from HE-SIG-A or U-SIG, and the value specific to the BSS differs from that of the BSS to which the device belongs, the wireless receiver 404 may interrupt the acquisition of the frame.

[0055] The wireless receiver 404 monitors the received signal from the antenna 406. If no signal with received power exceeding a predetermined energy detection (ED) CCA level (hereinafter also referred to as the CCA-ED level) is detected, it sets the CCA indication (also referred to as the PHY-CCA indication), which shows whether the wireless medium is available, to idle and outputs it to the carrier sense unit 405. If a signal with received power exceeding the CCA-ED level is detected, it sets the CCA indication to busy and notifies the carrier sense unit 405.

[0056] When the wireless receiver 404 detects L-STF and L-LTF from the received signal with a received power equal to or greater than a predetermined signal detection (SD) CCA level (hereinafter also referred to as the CCA-SD level), it sets the CCA indication to a busy state and notifies the carrier sense unit 405. This received power detection is also called preamble detection. Furthermore, if the wireless receiver 404 successfully acquires the L-SIG field, it maintains the CCA indication in a busy state for a period based on the LENGTH subfield within the L-SIG field. The wireless receiver 404 may set the CCA-ED level higher than the CCA-SD level; for example, it may set the CCA-SD level to -82 dBm and the CCA-ED level to -62 dBm. Furthermore, if a value specific to the BSS, such as BSS Color, is obtained from HE-SIG-A or U-SIG, and that value differs from that of the BSS to which the device belongs, the wireless receiver 404 may change the CCA-SD level to a higher value. In this case, it is preferable for the wireless transmitter 403 to reduce the transmission power in conjunction with the increase in the CCA-SD level.

[0057] The carrier sense unit 405 receives a CCA indication from the wireless receiver unit 404, and receives the identification result from the communication control unit 402 as to whether the received MPDU is addressed to its own device, whether it is an intra-BSS frame or an inter-BSS frame, and duration information. This carrier sense based on the CCA indication is called physical carrier sense (physical CS).

[0058] The carrier sense unit 405 is equipped with an indicator called NAV (Network Allocation Vector) that maintains the time periods during which the device does not transmit frames to the wireless medium, regardless of the physical CS status. The NAV can be represented as a countdown timer and is also called a NAV timer or NAV counter. Hereafter, the NAV will be described as being represented as a countdown timer, but it is not limited to this. The carrier sense unit 405 of a terminal device is equipped with two types of NAV: basic NAV and intra-BSS NAV. The carrier sense unit 405 of an access point device may also be equipped with two types of NAV: basic NAV and intra-BSS NAV. Details on updating the NAV value will be described later.

[0059] The carrier sense unit 405 determines that the virtual carrier sense (virtual CS) is idle if both the basic NAV and the intra-BSS NAV are 0, and determines that the virtual CS is busy if at least one NAV is not zero.

[0060] The carrier sense unit 405 outputs to the communication control unit 402 that the carrier sense result is idle when both the physical CS and virtual CS are idle, and outputs that the carrier sense result is busy when either the physical CS or the virtual CS is busy.

[0061] Figure 5 shows an example of the process of adding a PE field to the end of a PHY layer frame in the IEEE 802.11ax standard. In generating a PPDU, the wireless transmitter 403 applies error correction coding to the information bits of the PSDU to be transmitted. Figure 5 shows an example where LDPC (Low Density Parity Check) coding is used as the error correction coding. LDPC coding is performed for each block of LDPC information block length, which is selected based on the number of information bits in the PSDU, the modulation and coding scheme (MCS), and the number of coded bits per OFDM symbol, and coded bits with an LDPC codeword block length are output.

[0062] During LDPC encoding, it is possible that the remaining information bits at the end of the PSDU may be less than the selected LDPC information block length. In this case, the pre-FEC (Forward Error Correction) padding processing unit 501 adds pre-FEC padding bits 503 to the remaining information bits (excess information bits 502) so that the total length becomes the selected LDPC information block length. The excess information bits 502 with the pre-FEC padding bits 503 added are scrambled by the scrambler 504 and input to the FEC encoder 505. If the addition of pre-FEC padding bits 503 is not necessary, the information bits are input directly to the scrambler 504, scrambled, and input to the FEC encoder 505. The FEC encoder 505 performs LDPC encoding on the input scrambled bit sequence and outputs the encoded bits, the FEC output bits 507, to the post-FEC padding processing unit 506.

[0063] The FEC output bit 507 described above fills up to one of the pre-FEC padding boundaries P509, P510, P511, and P512, which divide the last OFDM symbol in the Data field into four symbol segments. Figure 5 shows an example where the FEC output bit 507 fills up to the second pre-FEC padding boundary P510.

[0064] The parameter that indicates how much of the four pre-FEC padding boundaries is filled with FEC output bits 507 is defined as the pre-FEC padding coefficient a. For the first pre-FEC padding boundary P509, a=1; for the second pre-FEC padding boundary P510, a=2; for the third pre-FEC padding boundary P511, a=3; and for the fourth pre-FEC padding boundary P512, a=4. Figure 5 shows an example where the pre-FEC padding coefficient a is 2. The pre-FEC padding coefficient a can be notified in the control field within the PPDU, for example, in the Pre-FEC Padding Factor subfield within the HE-SIG-A field or the EHT-SIG field.

[0065] The pre-FEC padding coefficient a is equal to the number of bits N of the excess information bits 502. Ｅｘｃｅｓｓ N data bits per OFDM symbol ＤＢＰＳ N encoding bits per OFDM symbol ＣＢＰＳ It can be calculated using a formula based on these factors.

[0066] The post-FEC padding processing unit 506 adds a post-FEC padding bit 508 to the FEC output bit 507 so that the last OFDM symbol in the Data field is filled up to the fourth pre-FEC padding boundary P512, and inputs it to the OFDM modulator 513. Figure 5 shows an example in which the post-FEC padding bit 508 is added to the FEC output bit 507 to fill the pre-FEC padding boundary from P510 to P512. Note that if the FEC output bit 507 is filled up to the pre-FEC padding boundary P512, that is, if the pre-FEC padding coefficient a is 4, the post-FEC padding bit 508 is not added.

[0067] The OFDM modulator 513 generates a modulation symbol by applying digital modulation to the input FEC output bits 507 and post-FEC padding bits 508, maps the modulation symbol to each data subcarrier, and performs a Discrete Fourier Transform (DFT) to output an OFDM symbol 515. In this case, a guard interval (GI) is added to the OFDM symbol 515. When performing MIMO (multiple-input and multiple-output) transmission using multiple spatial streams, the OFDM modulator 513 may rearrange the input FEC output bits 507 and post-FEC padding bits 508 for use with multiple spatial streams. Also, when performing transmission using multiple frequency blocks, the OFDM modulator 513 may divide the input FEC output bits 507 and post-FEC padding bits 508 into multiple parts.

[0068] The packet extension processing unit 514 may append a PE field 516 to the end of the transmitted frame in order to ensure sufficient time for reception processing at the receiving wireless communication device. The duration of the PE field appended to each PPDU is determined based on the pre-FEC padding coefficient a and the duration specified by NOMINAL_PACKET_PADDING, one of the TXVECTOR parameters of the control parameters input from the MAC layer to the PHY layer. The PE field 516 must be transmitted with the same average power as the Data field and must not cause significant power leakage outside the spectrum used by the Data field, but other contents are optional.

[0069] Figure 6 shows an example of a table of PE field durations in the IEEE 802.11ax standard. As shown in Figure 6, in the IEEE 802.11ax standard, the duration of the PE field is determined to be either 0 μs (microseconds), 4 μs, 8 μs, 12 μs, or 16 μs based on one of three values ​​(value0, value1, and value2) specified by the TXVECTOR parameter NOMINAL_PACKET_PADDING and the value of the pre-FEC padding coefficient a. In other words, the duration of the PE field is determined by subtracting the time corresponding to the length of the post-FEC padding bits that do not require LDPC decoding processing on the receiving side from the duration indicated by the TXVECTOR parameter NOMINAL_PACKET_PADDING. In this case, the durations indicated by value0 to value2 are 0 μs, 8 μs, and 16 μs, respectively. Figure 7 similarly shows examples of the duration of a PE field in the IEEE 802.11be standard. As shown in Figure 7, in the IEEE 802.11be standard, there are four values ​​specified by the TXVECTOR parameter NOMINAL_PACKET_PADDING, from value0 to value4, which indicate durations of 0 μs, 8 μs, 16 μs, and 20 μs, respectively.

[0070] The value specified by the TXVECTOR parameter NOMINAL_PACKET_PADDING can be notified by the communication partner's wireless terminal device as part of the Capabilities element. Alternatively, the PPE (PHY Packet Extension) threshold, indicated by the Constellation Index representing the modulation scheme, which is used to determine the value of the TXVECTOR parameter NOMINAL_PACKET_PADDING from the allocated resource unit (RU) size and the number of spatial streams, may be notified by the communication partner's wireless terminal device as part of the Capabilities element.

[0071] In wireless LAN systems, beamforming technology can be used to control the directivity of the transmit and receive beams, aiming to improve transmit and receive gain and enhance the reception characteristics of MIMO communication. For example, multiple transmit weight vectors or transmit weight matrices that achieve different transmit beam directivity can be defined, and when transmitting a frame, one of these transmit weight vectors (or matrices) can be selected for transmit beamforming. The selected transmit weight vector (or matrix) can be indicated by an index. Similarly, multiple receive weight vectors or receive weight matrices that achieve different receive beam directivity can be defined, and when receiving a frame, one of these receive weight vectors (or matrices) can be selected for receive beamforming. The selected receive weight vector (or matrix) can be indicated by an index. As another example, a codebook of transmit and receive weights can be prepared, and one can be selected from the codebook for beamforming. The selected codebook can also be indicated by an index. The following explanation will use transmit weight vectors and receive weight vectors as examples, but the method is not limited to these; it can be similarly implemented using transmit weight matrices and receive weight matrices or codebooks.

[0072] In high-frequency bands such as the millimeter wave and terahertz bands, propagation loss is significant, making it crucial to use beamforming with a narrow beamwidth (narrow beam half-angle) to increase transmission and reception gain. However, if the wireless communication equipment is moving, or if people or objects are moving in the propagation environment, the propagation path may fluctuate over time, potentially leading to a deterioration in communication quality or link disconnection. Therefore, it is necessary to perform timely beam tracking (beam tracking, beam training, beam refinement, etc.) to ensure that the beam's directivity follows the time fluctuations of the propagation path.

[0073] Therefore, beam tracking is performed by including a beam tracking signal (hereinafter referred to as the beam tracking signal) in the PE field, based on the PPDU format in the IEEE 802.11ax and IEEE 802.11be standards for the sub-7GHz frequency band. At this time, information indicating whether or not the beam tracking signal is included in the PE field may be included in the control information within the PPDU, such as various SIGNAL fields (VHT-SIG-A, VHT-SIG-B, HE-SIG-A, HE-SIG-B, EHT-SIG, or U-SIG). Alternatively, information indicating whether or not the beam tracking signal is included in the PE field may be included in the control information within the MAC header. In the following explanation, the information indicating whether or not the beam tracking signal is included in the PE field will be referred to as beam tracking information, and the field in the control information containing the beam tracking information will be referred to as the beam tracking field. Furthermore, while it is explained that beam tracking information is set to 1 if a beam tracking signal is included in the PE field, and 0 if it is not, this is not the only explanation.

[0074] Figure 8 shows an example of a PPDU with beam tracking signals inserted into the PE field. In PPDU 801 of Figure 8, an example of a PPDU is shown in which N beam tracking signals 803-1 to N are included in the PE field 802. When used for tracking a transmitted beam, the N beam tracking signals 803-1 to N can each be subjected to transmitted beamforming with different transmission weights. Each beam tracking signal 803-1 to N is transmitted with the same average power. Furthermore, it is preferable that each beam tracking signal 803-1 to N is transmitted with the same average power as the Data field.

[0075] The beam tracking signals 803-1 to N may include a transmission weight vector used for transmitting beamforming of the Data field of the PPDU 801, and beam tracking signals based on one or more transmission weight vectors such that the direction of maximum gain of the formed beam is spatially close to the direction of maximum gain of the beam due to the said transmission weight vector. Alternatively, the beam tracking signals 803-1 to N may include beam tracking signals based on one or more transmission weight vectors other than the transmission weight vector used for transmitting beamforming of the Data field of the PPDU 801, such that the direction of maximum gain of the formed beam is spatially close to the direction of maximum gain of the beam due to the said transmission weight vector.

[0076] The wireless communication device that receives the PPDU 801 receives beam tracking signals 803-1 to N and measures the received power of each. If each of the beam tracking signals 803-1 to N consists of M (M≧1) OFDM symbols, the received power may be measured using one or more OFDM symbols from the mth (m≦M) onward for each of the beam tracking signals 803-1 to N. In particular, if M>1 and m<M, even in the case of analog beamforming or hybrid beamforming, it becomes possible to measure the received power using the beam tracking signal after the transmitting output of the transmitting side has stabilized. The number of OFDM symbols M and the predetermined number m may be notified in advance from the transmitting wireless communication device to the receiving wireless communication device, or they may be included in the control information within the PPDU 801 and transmitted.

[0077] The receiving wireless communication device notifies the transmitting wireless communication device of the PPDU 801 of the index k of the beam tracking signal 803-k that had the highest measured received power. The index k to be notified may represent the position (order) of the beam tracking signal with the highest received power within the PE field, and can be represented from 1 to N with 1 at the beginning, or from 0 to N-1 with 0 at the beginning.

[0078] Furthermore, if the beam tracking signals 803-1 to N do not include the beam tracking signal that has been beamformed by the transmit weight vector used for transmit beamforming of the Data field of the PPDU 801, the receiving wireless communication device may, for example, measure the received power of the training signal or Data field of the VHT-LTF, HE-LTF, or EHT-LTF of the PPDU 801, compare it with the measured received power of each beam tracking signal 803-1 to N, and notify the transmitting wireless communication device of the one with the highest received power among them. In this case, the index of the training signal or Data field of the VHT-LTF, HE-LTF, or EHT-LTF of the PPDU 801 may be set to 0, and the index of the beam tracking signals 803-1 to N may be set to 1 to N.

[0079] In a transmitting wireless communication device, when switching transmission weights between beam tracking signals, time may be required for the transmission output of the beam-formed beam tracking signal to stabilize after the switch. In particular, analog beamforming and hybrid analog-digital beamforming require time to change the phase and amplitude of the antenna array elements. Therefore, it is preferable that each beam tracking signal 803-1 to N has a duration that ensures a duration greater than or equal to the sum of the time required for the transmission output of the beam-formed signal to stabilize and the time required for receiving power measurement on the receiving side. Each beam tracking signal 803-1 to N may be composed of multiple OFDM symbols to ensure the above duration.

[0080] The OFDM symbol for the PE field, which includes the beam tracking signal, may have a different configuration from the OFDM symbol for the Data field. For example, if we consider a case where communication is performed using a 640 MHz bandwidth in the millimeter wave band, reusing the parameters for an 80 MHz bandwidth in the Sub-7 GHz band, the Data field may use an OFDM symbol with 996 data subcarriers (1024 DFT points) and an effective symbol length of 1.6 μs, while the PE field may use an OFDM symbol with 242 data subcarriers (256 DFT points) and an effective symbol length of 0.4 μs. Furthermore, to illustrate with an example where the parameters for a 160 MHz bandwidth in the Sub-7 GHz band are reused to perform communication using a 1280 MHz bandwidth in the millimeter wave band, the Data field may use OFDM symbols with 1992 data subcarriers (2048 DFT points) and an effective symbol length of 1.6 μs, while the PE field may use OFDM symbols with 484 data subcarriers (512 DFT points) and an effective symbol length of 0.4 μs.

[0081] The beam tracking signal may consist of modulation symbols generated using BPSK (Binary Phase-Shift Keying) or QPSK (Quadrature Phase-Shift Keying), which are phase-shift modulations with constant amplitude, regardless of the modulation scheme of the data field. Alternatively, the beam tracking signal may be generated from a bit sequence or modulation symbol sequence that reduces the peak-to-average power ratio (PAPR) of the OFDM symbols. For example, a CAZAC (Constant Amplitude Zero Auto-Correlation) sequence or a Zadoff-Chu sequence may be used as the information bits.

[0082] If the PE field contains a beam tracking signal, the information indicating the duration of wireless media occupancy caused by the transmission of the PPDU, such as the LENGTH subfield of the L-SIG field or the Duration field of the MAC header, will include the duration of the PE field (i.e., the total duration of all beam tracking signals).

[0083] If the PE field does not contain a beam tracking signal, the duration of the PE field can be determined, as described above, based on the pre-FEC padding coefficient a and the value specified by the TXVECTOR parameter NOMINAL_PACKET_PADDING, for example, using the table in Figure 6.

[0084] On the other hand, when the PE field includes a beam tracking signal, the duration of the PE field can be determined using a different table than the one used when the beam tracking signal is not included, for example, the table in Figure 9, based on the value specified by the TXVECTOR parameter NOMINAL_PACKET_PADDING. Figure 9 shows an example where, regardless of the pre-FEC padding coefficient a, the duration of the PE field can be determined to be 4 μs, 8 μs, or 12 μs based on the value of the TXVECTOR parameter NOMINAL_PACKET_PADDING. The values ​​of 4 μs, 8 μs, and 12 μs listed as examples of PE field durations in Figure 9 represent durations equivalent to 10, 20, and 30 OFDM symbols, respectively, assuming an OFDM effective symbol length of 0.4 μs for the beam tracking signal. Note that the values ​​and options for the duration are not limited to those listed above.

[0085] Another example of including beam tracking signals in the PE field is to use a table that determines the number of beam tracking signals N based on the value specified by the TXVECTOR parameter NOMINAL_PACKET_PADDING. Figure 10 shows an example of a table where the number of beam tracking signals N can be 4, 8, or 12 based on the value specified by the TXVECTOR parameter NOMINAL_PACKET_PADDING. The duration of the PE field can be determined by multiplying the value of the number of beam tracking signals N shown in the table in Figure 10 by the duration of each beam tracking signal. The duration of each beam tracking signal can be set to a duration that ensures a duration greater than or equal to the sum of the time required for the transmission output of the beamformed signal on the transmitting side to stabilize and the time required for the received power measurement on the receiving side, and this duration may be included in control information such as Capabilities information and notified between the transmitting and receiving wireless communication devices in advance. Note that the options for the number of beam tracking signals N are not limited to those described above.

[0086] The above describes a method for determining the duration of a PE field when it includes a beam tracking signal, using the TXVECTOR parameter NOMINAL_PACKET_PADDING, similar to the case where the PE field does not include a beam tracking signal. However, this is not the only method. If a new TXVECTOR parameter is defined to indicate that the beam tracking information includes a beam tracking signal in the PE field, the duration of the PE field can also be determined based on the new TXVECTOR parameter instead of NOMINAL_PACKET_PADDING.

[0087] Next, we will explain, using Figure 8, the case in which the beam tracking signal included in the PE field is used for tracking the received beam in the receiving wireless communication device. From here on, we will omit explanations of parts that are the same as those for transmit beamforming. When beam tracking signals 803-1 to N are used for tracking the received beam, it is preferable that beam tracking signals 803-1 to N are subjected to beamforming with the same transmit weights as the Data field.

[0088] The wireless communication device receiving the PPDU 801 can apply beamforming with different receiving weights to each beam tracking signal 803-1 to N when receiving them. The receiving wireless communication device measures the received power of each beam tracking signal 803-1 to N while changing the receiving weight, and can use the receiving weight that yields the maximum measured received power when receiving the next frame from the PPDU 801 source wireless communication device. Alternatively, the receiving wireless communication device may measure the received power of, for example, the VHT-LTF, HE-LTF, or EHT-LTF training signal or Data field of the PPDU 801, which has been received with beamforming using the currently set receiving weight, compare it with the measured received power of each beam tracking signal 803-1 to N received while changing the receiving weight, and use the receiving weight that yields the maximum received power among them for beamforming when receiving the next frame from the PPDU 801 source wireless communication device.

[0089] In the receiving wireless communication device, when switching the receiving weight between each beam tracking signal, time may be required for the received signal input of the beam-formed beam tracking signal to stabilize according to the switched receiving weight. Therefore, similar to the case of transmitting beamforming, it is preferable that each beam tracking signal 803-1 to N has a duration that ensures a time equal to or greater than the sum of the time required for the received beam-formed received signal input to stabilize and the time required for receiving power measurement. Each beam tracking signal 803-1 to N may be composed of multiple OFDM symbols to ensure the above duration.

[0090] The duration of the PE field, the duration of each beam tracking signal, etc., may be set in the same way as for transmit beamforming. (Common to all embodiments)

[0091] A wireless communication device according to one aspect of the present invention can communicate in a frequency band (frequency spectrum) known as the so-called unlicensed band, which does not require permission from a country or region for use, but the usable frequency bands are not limited to this. A wireless communication device according to one aspect of the present invention can also be effective in frequency bands known as white bands, which are not actually used for purposes such as preventing interference between frequencies, even though permission for use for specific services has been granted by a country or region (for example, frequency bands allocated for television broadcasting but not used in some regions), and in shared spectrums (shared frequency bands) that are expected to be shared by multiple operators.

[0092] A program that operates in a wireless communication device according to one aspect of the present invention is a program that controls the CPU and other components (a program that makes the computer function) in order to realize the functions of the above-described embodiment according to one aspect of the present invention. The information handled by these devices is temporarily stored in RAM during processing, and then stored in various ROMs or HDDs, and read, modified, and written by the CPU as needed. The recording medium for storing the program may be any of the following: semiconductor media (e.g., ROM, non-volatile memory card, solid-state drive, etc.), optical recording media (e.g., DVD, MO, MD, CD, BD, etc.), magnetic recording media (e.g., magnetic tape, flexible disk, etc.). Furthermore, in addition to realizing the functions of the above-described embodiment by executing the loaded program, the functions of the present invention may also be realized by processing in cooperation with the operating system or other application programs based on the instructions of the program.

[0093] Furthermore, when distributing the program to the market, it can be stored on a portable recording medium and distributed, or transferred to a server computer connected via a network such as the Internet. In this case, the storage device of the server computer is also included in one aspect of the present invention. In addition, some or all of the wireless communication device in the above-described embodiment may be implemented as an LSI, which is typically an integrated circuit. Each functional block of the wireless communication device may be individually chipped, or some or all of them may be integrated into a single chip. When each functional block is implemented as an integrated circuit, an integrated circuit control unit is added to control them. Needless to say, the case in which programs and configuration information are downloaded from a server computer in order to implement at least some of the functions of the above-described embodiment is also included in one aspect of the present invention.

[0094] Furthermore, the method of implementing integrated circuits is not limited to LSIs; it may also be implemented using dedicated circuits or general-purpose processors. Additionally, if advancements in semiconductor technology lead to the emergence of integrated circuit technologies that can replace LSIs, it is possible to use integrated circuits based on those technologies.

[0095] It should be noted that the embodiments of the present invention are not limited to those described above. The wireless communication device of the present invention is not limited to application to mobile station devices, but can also be applied to stationary or non-movable electronic devices installed indoors or outdoors, such as AV equipment, kitchen appliances, cleaning and washing machines, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0096] While embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and designs that do not depart from the spirit of this invention are also included in the claims.

[0097] One aspect of the present invention is suitable for use in wireless communication devices and wireless communication methods.

[0098] 100-1, 100-2 Basic service set 101-1, 101-2 Access point device 102-1, 102-2 Terminal device 400 Wireless communication device 401 Upper layer 402 Communication control unit 403 Wireless transmission unit 404 Wireless reception unit 405 Carrier sense unit 406 Antenna unit 501 Pre-FEC padding processing unit 502 Excess information bits 503 Pre-FEC padding bits 504 Scrambler 505 FEC encoder 506 Post-FEC padding processing unit 507 FEC output bits 508 Post-FEC padding bits P509, P510, P511, P512 Pre-FEC padding boundary 513 OFDM modulator 514 Packet extension processing unit 515 OFDM symbol 516 PE field 801 PPDU 802 PE field 803-1, 803-2, 803-N Beam tracking signal

Claims

1. A first wireless communication device comprising a wireless transmission unit and a control unit, wherein the control unit includes in the control field of a transmission frame first information indicating whether or not the packet extension field of the transmission frame includes a beam tracking signal, the wireless transmission unit transmits the transmission frame to a second wireless communication device, and the duration of the packet extension field is set by the first information and a table, a calculation formula, or both.

2. The wireless communication device according to claim 1, wherein the table, the calculation formula, or both used when the first information indicates that the packet extension field does not contain a beam tracking signal is different from the table, the calculation formula, or both used when the first information indicates that the packet extension field contains a beam tracking signal.

3. The wireless communication device according to claim 2, wherein the beam tracking signal includes a plurality of subfields, each of which is beamformed.

4. The wireless communication device according to claim 2, wherein the modulation symbol of the beam tracking signal is generated using phase shift modulation, regardless of the modulation scheme of the data field of the transmission frame.

5. The wireless communication device according to claim 3, further comprising a wireless receiving unit, wherein the wireless receiving unit receives a frame from the second wireless communication device that includes a second piece of information representing an index indicating any one of the plurality of subfields.

6. A second wireless communication device comprising a wireless receiving unit, a wireless transmitting unit, and a control unit, wherein the wireless receiving unit receives a frame transmitted by a first wireless communication device, the control field of the received frame includes first information indicating whether or not the packet extension field of the received frame includes a beam tracking signal, and the control unit identifies the duration of the packet extension field based on the first information and a table, a calculation formula, or both.

7. The wireless communication device according to claim 6, wherein the control unit selects one of a plurality of subfields included in the beam tracking signal when the first information indicates that the packet extension field includes the beam tracking signal, and the wireless transmission unit transmits a frame including second information indicating the index of the selected subfield to the first wireless communication device.

8. The wireless communication device according to claim 7, wherein the wireless receiving unit measures the received power of each of the plurality of subfields included in the beam tracking signal, and the control unit selects the subfield with the maximum received power from among the plurality of subfields.

9. A wireless communication method in a first wireless communication device, comprising the steps of: including in the control field of a transmission frame first information indicating whether or not the packet extension field of the transmission frame includes a beam tracking signal; and transmitting the transmission frame to a second wireless communication device, wherein the duration of the packet extension field is set by the first information and by a table, a calculation formula, or both.

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