Communication device, control method, and program

Abstract

Disclosed is a communication device comprising a transmission means for transmitting a MU PPDU including, in a preamble, a U-SIG and a specific SIG following the U-SIG. The specific SIG includes control information for identifying an MCS that is a modulation method and an encoding rate of a data part of each of the plurality of streams, the control information being directed to one or more specific communication devices. The control information can include first specific information. The first specific information indicates that a data part of a first stream among a plurality of streams is modulated and encoded by a first MCS, a data part of a second stream among the plurality of streams is modulated and encoded by a second MCS, and the second MCS is different from the first MCS.

Description

Communication device, control method, and program

[0001] The present disclosure relates to a communication device, a control method, and a program.

[0002] In recent years, with the increase in the amount of data being communicated, the development of communication technologies such as wireless local area networks (LANs) has been progressing. The IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard series is known as the main communication standard for wireless LANs. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax / be.

[0003] Currently, the IEEE 802.11bn Task Group (TG) is working on a successor standard to the IEEE 802.11be standard to further improve throughput and communication reliability. The 802.11bn TG has passed through a Study Group (SG) called IEEE 802.11 Ultra High Reliability (UHR).

[0004] The IEEE 802.11 standard defined MIMO (Multi-Input-Multi-Output) communication, which allows simultaneous communication using multiple streams, starting with 11n as a way to improve throughput, and has continued to be adopted in 11ac, 11ax, and 11be. Furthermore, to support multi-user communication and reduce communication latency, OFDMA communication was adopted as the secondary modulation method starting with 11ac. OFDMA stands for Orthogonal Frequency Division Multiple Access. 11ac adopted Downlink-OFDMA communication, while 11ax, the next-generation standard for 11ac, adopted Uplink-OFDMA communication in addition to Downlink-OFDMA communication. 11bn is expected to follow this trend and adopt DL (Downlink) / UL (Uplink)-OFDMA communication.

[0005] Since 11ac, OFDMA communication has been used as the secondary modulation method, but the primary modulation method uses an adaptive modulation method that selects an appropriate modulation method from multiple modulation methods depending on the communication environment. To improve throughput, multi-level modulation methods have been added to the primary modulation, and 11be supports BPSK, QPSK, 16QAM, 64QAM, 256QAM, 1024QAM, and 4096QAM. Communication is carried out by assigning a Modulation and Coding Scheme (MCS), defined by a combination of modulation method and coding rate, to each user.

[0006] Regarding MIMO communication, DL MIMO communication has been adopted since IEEE802.11ac, and UL-MIMO has been adopted in IEEE802.11ax. This has improved UL communication capacity, and DL / UL-MIMO is expected to continue to be adopted in IEEE802.11be and beyond.

[0007] The IEEE is currently studying many measures to improve communication reliability, in addition to improving throughput and reducing communication delay time through multi-user communication.

[0008] Patent No. 5436863 specification

[0009] IEEE 802.11be allows MIMO communication with up to eight streams (in single-user communication). To communicate with eight streams, eight antennas are required within each of the AP (Access Point) and STA (Station). However, since the propagation paths for each of the eight streams are separate, there is a possibility that differences in propagation loss may occur. For example, portable mobile devices such as smartphones are often held in the hand, and therefore, it is expected that certain antennas may be blocked by the hand, resulting in a decrease in transmission and reception power.

[0010] IEEE802.11 employs adaptive modulation, and performs control to assign an appropriate modulation method to each STA (each user) according to the communication environment. In contrast, in MIMO communication, which uses multiple streams for communication, control to assign an appropriate modulation method to each stream is not performed for the same STA. In other words, in MIMO communication, which uses multiple streams for communication, the same modulation method and coding rate are assigned to all streams for the same STA.

[0011] For example, a difference in received power occurs between an unobstructed antenna and an antenna obstructed by a hand, resulting in a difference in signal-to-noise ratio (SNR). A stream communicating with an unobstructed antenna satisfies the required SNR, enabling communication without communication errors. On the other hand, a stream communicating with an antenna obstructed by a hand may not satisfy the required SNR, resulting in frequent communication errors. As a result, the effect of improving throughput using multiple streams is reduced.

[0012] The present invention has been made in consideration of at least one of the above-mentioned problems. One aspect of the present invention aims to provide a mechanism for preventing a decrease in the effect of improving throughput due to multiple streams. Another aspect of the present invention aims to provide a mechanism for controlling a function for assigning an appropriate modulation scheme to each stream.

[0013] A communication device according to one aspect of the present invention comprises a transmitting means for transmitting an MU (Multi-User) PPDU (Physical Layer Protocol Data Unit) including a U-SIG (Universal Signal field) and a specific SIG following the U-SIG in a preamble, wherein the specific SIG includes control information for specifying an MCS (Modulation and Coding Scheme) that is a modulation method and a coding rate for a data portion of each of a plurality of streams, the control information being directed to one or more specific communication devices, and wherein the control information can include first specification information, and the first specification information indicates that a data portion of a first stream of the plurality of streams is modulated and coded with a first MCS, and that a data portion of a second stream of the plurality of streams is modulated and coded with a second MCS, The second MCS is different from the first MCS.

[0014] According to one aspect of the present invention, it is possible to provide a mechanism for preventing a decrease in the effect of improving throughput due to multiple streams, and according to another aspect of the present invention, it is possible to provide a mechanism for controlling a function for assigning an appropriate modulation scheme to each stream.

[0015] FIG. 1 is a diagram illustrating an example of a network configuration. FIG. 2 is a diagram illustrating an example of a hardware configuration of a communication device. FIG. 3 is a sequence diagram of an example of non-trigger-based communication. FIG. 4 is a diagram illustrating an example of a preamble configuration for single-user communication. FIG. 5 is a diagram illustrating an example of an MCS / stream setting configuration (part 1) of a preamble for single-user communication. FIG. 6 is a diagram illustrating an example of an MCS setting table. FIG. 7 is a diagram illustrating an example of MCS setting in a preamble for single-user communication. FIG. 8 is a diagram illustrating an example of a preamble configuration for multi-user communication. FIG. 9 is a diagram illustrating an example of an MCS / stream setting configuration of a preamble for multi-user communication. FIG. 10 is a diagram illustrating an example of setting the number of streams for each user in multi-user communication. FIG. 11 is a diagram illustrating an example of MCS setting in a preamble for multi-user communication. FIG. 12 is a sequence diagram of an example of trigger-based communication. FIG. 13 is a diagram illustrating an example of a trigger frame format. FIG. 14 is a diagram illustrating another example of an MCS setting table. FIG. 15 is a diagram illustrating an example of the configuration of capability information that a device notifies to the outside in a modified example.

[0016] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Although the embodiments describe a plurality of features, not all of these features are necessarily essential to the invention, and the plurality of features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0017] (Configuration of Wireless Communication System) FIG. 1 shows the configuration of a wireless network 100 to which communication devices 101, 102, 103, and 104 according to this embodiment belong. The communication device 101 is an AP, and the communication devices 102, 103, and 104 are STAs. Each of the communication devices 101, 102, 103, and 104 can perform wireless communication in accordance with standards such as IEEE 802.11ax / be / bn. Each of the communication devices 101, 102, 103, and 104 may also be in accordance with standards after IEEE 802.11be. Each communication device can communicate in frequencies of the 2.4 Hz band, 3.6 GHz band, 5 GHz band, and 6 GHz band, as well as the 45 GHz band and 60 GHz band, which are called millimeter waves.

[0018] The frequency bands used by each communication device are not limited to these, and different frequency bands such as the Sub-1 GHz band may be used. Furthermore, communication devices 101, 102, 103, and 104 can communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 540 MHz, 640 MHz, 1080 MHz, and 2160 MHz. The bandwidths used by each communication device are not limited to these, and different bandwidths such as 240 MHz and 4 MHz may be used.

[0019] The communication devices 101, 102, 103, and 104 can realize multi-user (MU) communication by performing OFDMA communication conforming to standards such as IEEE 802.11ax / be / bn. Multi-user communication is a communication format in which signals from multiple users are multiplexed. In OFDMA communication, some RUs (Resource Units) of a divided frequency band are assigned to each STA so as not to overlap, and the carrier waves of each STA are orthogonal. Therefore, an AP can communicate simultaneously with multiple STAs within a specified bandwidth. Specific examples of the communication device 101 include, but are not limited to, a wireless LAN router and a personal computer (PC).

[0020] Specific examples of the communication devices 102, 103, and 104 include, but are not limited to, cameras, tablets, smartphones, PCs, mobile phones, video cameras, and headsets. The communication devices 102, 103, and 104 may also be information processing devices such as wireless chips capable of performing wireless communication in accordance with the IEEE 802.11ax / be / bn standards.

[0021] Although the wireless network 100 in Fig. 1 is configured with one AP and three STAs, the number of APs and STAs is not limited to this. For example, the number of STAs may be two or four or more. Furthermore, in the case of single-user communication described below with reference to Fig. 3 etc., the number of STAs may be one.

[0022] (Configuration of AP and STA) FIG. 2 shows a hardware configuration that can be commonly applied to the AP and the STA in this embodiment.

[0023] An example of the hardware configuration includes a storage unit (201), a control unit (202), a function unit (203), an input unit (204), an output unit (205), a communication unit (206), and an antenna (207).

[0024] The storage unit (201) is configured with memories such as ROM and RAM, and stores various information such as programs for performing various operations described below and communication parameters for wireless communication. Note that, in addition to memories such as ROM and RAM, the storage unit (201) may also use storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs. The storage unit (201) may also include multiple memories.

[0025] The control unit (202) is composed of, for example, a processor such as a CPU or MPU, an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), etc. Here, CPU is an acronym for Central Processing Unit, and MPU is an acronym for Micro Processing Unit. The control unit (202) controls the AP by executing a program stored in the storage unit (201). Note that the control unit (202) may control the AP in cooperation with the program stored in the storage unit (201) and an OS (Operating System). The control unit (202) may also be composed of multiple processors, such as a multi-core processor, and control the AP.

[0026] The control unit (202) also controls the function unit (203) to perform predetermined processes such as AP functions, STA functions, image capture, printing, projection, etc. The function unit (203) is hardware that enables the AP to perform predetermined processes.

[0027] The input unit (204) receives various operations from the user. The output unit (205) outputs various types of information to the user. Here, the output by the output unit (205) includes at least one of display on a screen, audio output from a speaker, vibration output, etc. Note that both the input unit (204) and the output unit (205) may be realized by a single module, such as a touch panel.

[0028] The communication unit (206) controls wireless communication conforming to the IEEE 802.11bn standard, wireless communication conforming to Wi-Fi (registered trademark), and IP (Internet Protocol) communication. Furthermore, the communication unit (206) controls an antenna (207) to transmit and receive wireless signals for wireless communication.

[0029] Although only one antenna (207) is shown in the figure for simplicity, it is assumed that multiple antennas are provided. Generally, the number of antennas (207) corresponds to the number of streams available for the corresponding MIMO communication. That is, the communication unit 206 cooperates with the antenna 207 to transmit and receive UHR PPDUs, which are wireless frames conforming to the IEEE 802.11bn standard. UHR PPDU is an abbreviation for Ultra High Reliability Physical Layer Protocol Data Unit.

[0030] The name UHR was chosen for convenience, taking into account the goals and key features of the successor standard, and may be renamed once the standard is fully established. Similarly, the name IEEE 802.11bn may be renamed once the standard is fully established. However, please note that this specification and the accompanying claims are essentially applicable to all successor standards to the 802.11be standard. Furthermore, the AP 101 and the STA 102 can also transmit wireless frames corresponding to legacy standards that predate the IEEE 802.11bn standard. Examples of legacy standards include the IEEE 802.11a / b / g / n / ac / ax / be standards.

[0031] 3 shows a communication sequence diagram for single-user communication. STA (102) sends a probe request (300) to AP (101), and AP (101) responds to STA (102) with a probe response (301). Having received the probe response (301), STA (102) sends an authentication request (302) to AP (101), and AP (101) responds to STA (102) with an authentication response (303). Having received the authentication response (303), STA (102) sends a connection request (304) to AP (101), and AP (101) responds with a connection response (305). The AP (101) that sent the connection response (305) starts a sounding protocol sequence (306) and sends a sounding NDP (Null Data PPDU) (307) to the STA (102). The STA (102) that received the sounding NDP (307) sends a CQI (Channel Quality Indication) (308) calculated based on the sounding NDP (307) to the AP (101). This CQI (308) is the result of SNR calculation. The AP (101) sets an MCS (309) based on the result of CQI calculation. The MCS at this time is set for each stream based on the CQI for each stream. Then, the preamble signal carries MCS information for each stream, and the data frame (data portion) is transmitted with the MCS set for each stream applied (310). The configuration of the data frame generated and transmitted by the AP 101 in the data frame transmission (310) will be described in detail below. Note that soundings 306 to 308 can be omitted. If omitted, the AP 101 can determine the MCS for each stream based on past communication performance.

[0032] Fig. 4 shows an example (400) of a preamble signal and data configuration for single-user MIMO communication. Fig. 4 illustrates a UHR MU (Multi-User) PPDU used in single-user MIMO communication. UHR stands for Ultra High Reliability.

[0033] The UHR MU PPDU shown in FIG. 4 includes a Short Training Field (STF), a Long Training Field (LTF), a Signal Field (SIG), and a data field.

[0034] As shown in FIG. 4 , the beginning of the PPDU contains L (Legacy)-STF 4001, L-LTF 4002, and L-SIG 4003 to ensure backward compatibility with the IEEE 802.11a / b / g / n standards. L-LTF 4002 is placed immediately after L-STF 4001, and L-SIG 4003 is placed immediately after L-LTF 4002. Furthermore, RL-SIG (Repeated L-SIG, RL-SIG) 4004 is placed immediately after L-SIG 4003. In the RL-SIG field, the contents of L-SIG 4003 are repeatedly transmitted. RL-SIG 4004 enables the receiver to recognize that the PPDU is compliant with the IEEE 802.11ax standard or later.

[0035] The L-STF 4001 is used for detecting PHY frame signals, automatic gain control (AGC), timing detection, etc. The L-LTF 4002 is used for highly accurate frequency and time synchronization and for acquiring propagation channel information (CSI: Channel State Information). The L-SIG 4003 is used to transmit control information including information on data transmission rate and PHY frame length. Legacy devices that comply with the IEEE 802.11a / b / g / n / ax / be standards and devices that comply with IEEE 802.11bn or later standards can decode various legacy fields.

[0036] The PPDU further includes a U-SIG (Universal Signal Field) 4005 placed immediately after the RL-SIG 4004. The U-SIG 4005 is a field for transmitting control information for each standard, which is planned to be commonly used in standards from IEEE 802.11be onwards. The U-SIG 4005 is followed immediately by a UHR-SIG1 (401). The UHR-SIG1 (401) contains control information that does not fit into the U-SIG 4005 and control information that should be notified to each user when performing multi-user transmission. In the example shown in FIG. 4, since this is a PPDU for single-user communication, control information intended for one user is stored. This UHR-SIG1 (401) is modulated using the MCS specified in the UHR-SIG MCS field in the U-SIG 4005 (see Table 2 below).

[0037] Subsequently, UHR-SIG1 (401) is followed by UHR-STF 4006, which is an STF for UHR, and UHR-LTF 4007, which is an LTF for UHR. UHR-LTF 4007 is information used for MIMO estimation, beamforming estimation, etc. One or more UHR-LTFs 4007 can be placed based on the number of MIMO antennas and whether beamforming is required. In IEEE802.11be, a maximum of eight UHR-LTFs 4007 are placed.

[0038] 4, these control fields are followed by data field 4008 and packet extension field 4009. The fields from L-STF 4001 to UHR-LTF 4007 of this PPDU are called the PHY preamble.

[0039] Next, U-SIG 4005 included in the UHR MU PPDU described with reference to FIG. 4 will be described with reference to Table 1.

[0040] U-SIG4005 consists of two symbols (U-SIG1 and U-SIG2), each of which stores 25 bits of information. Tables 1 and 2 show the formats of U-SIG1 and U-SIG2, respectively.

[0041] The first three bits of U-SIG1 include a subfield that stores information for distinguishing the common wireless frame version (also called PHY Clauses). On the other hand, B3 to B25 of U-SIG1 and B0 to B15 of U-SIG2 include subfields that store control information customized for each standard.

[0042]

[0043]

[0044] When a communication device generates and transmits a wireless frame conforming to the IEEE 802.11bn standard based on the process described in FIG. 4, the communication device stores a 1 in the "PHY Version Identifier" subfield in Table 1. Specifically, the communication device stores a 0 in the "PHY Version Identifier" subfield, which is the region (B0-B2) from the header portion (0th bit) to the 2nd bit of the U-SIG. The communication device also stores a value corresponding to the bandwidth for transmitting the PPDU in the "Bandwidth" subfield in the 3-bit region (B3-B5) from the 3rd bit to the 5th bit of Table 1. The communication device also stores the UHR MCS used to modulate UHR-SIG1 (401), determined based on communication conditions, etc., in the "UHR-SIG MCS" subfield of U-SIG2. Another communication device that receives the UHR PPDU generated and transmitted by the communication device identifies the coding and modulation method of UHR-SIG1 (401) based on the MCS for UHR-SIG set in the "UHR-SIG MCS" subfield.The other communication device then assumes that UHR-SIG1 (401) has been modulated using the identified coding and modulation method and attempts to demodulate and decode UHR-SIG1 (401).

[0045] Furthermore, when transmitting a PPDU related to single-user MIMO communication, the communication device sets "1" to the PPDU Type and Compression Mode subfield. Note that when transmitting a PPDU related to multi-user MIMO communication, which will be described later, the communication device sets "0" or "3" to the PPDU Type and Compression Mode subfield. "0" is used when both OFDMA and MIMO are used, and "3" is used when MIMO is performed without using OFDMA technology. The communication device also sets values ​​based on the communication parameters in the other subfields as appropriate, and transmits the UHR MU PPDU.

[0046] Next, we will explain UHR-SIG1 (401). The communication device notifies the other device of the MCS setting for each stream as follows. That is, the notification is made using a combination of the User field (407) and Special User Info field (402) for one user of UHR-SIG1 (401) (an example of first specific information). The Special User Info field (402) is a field used when setting the MCS for each stream. This will be described in detail later.

[0047] Here, in this specification, unless otherwise specified, the term "MCS per stream" or a similar term refers to the MCS applied to the data portion of each stream (see data portion 809 in FIG. 8).

[0048] UHR-SIG1 (401) is composed of a Common field (403) and a User Specific field (404). The contents related to the MCS setting are notified using a combination of The common encoding block (405) and the 1st user encoding block (406) (an example of first specific information).

[0049] 5A and 5B show examples of the contents of the common encoding field (405) and the contents of the common field (403) during single-user MIMO communication. In the example shown in Fig. 5A, the contents related to the MCS for each stream are the subfields of the User field (500), MCS Group (501) and Nss (Number of spatial streams) (502), which indicates the number of streams. The MCS for each stream is notified by combining this content with the content of the Special User Info field (402) shown in Fig. 4 (an example of first specific information).

[0050] 5B shows an example of the contents of the Common field (403). The 13th bit, the EMCS subfield, is set with binary information (an example of second specific information) indicating whether or not an individual MCS is applied to each stream. When "0" is set, a common MCS is used for all streams, as in the previous standard 802.11bn. When "1" is set, it indicates that an individual MCS is applied to each stream, which is a feature of this embodiment. EMCS is an abbreviation for Enhancement MCS. Note that the field names are merely examples and are not limited to these.

[0051] When "0" is set in the EMCS subfield, the UHR-SIG is configured so as not to include the Special User Info field (402) described above. In this case, the MCS is indicated using the MCS subfield 503, which is a total of 4 bits, B11 to B14. In other words, when "0" is set in the EMCS field, a mechanism similar to the indication of the MCS in the data section in IEEE 802.11be can be used.

[0052] This section explains the conventional MCS indication mechanism and the method for specifying the MCS in the data section when the ECMS subfield is set to "0." In IEEE 802.11be, MCS is defined as 1 to 16, and 16 patterns indicate combinations of the QAM number, which is the data density per symbol, and the error correction coding rate.

[0053] By using a different MCS for each of the maximum eight streams, it is possible to optimize the MCS for each propagation path. However, if you try to indicate for each stream which of MCSs 1 to 16 the data is being transmitted with, you would essentially need 32 bits (4 bits x 8 streams).

[0054] On the other hand, in this embodiment, by adopting the concept of grouping in the method shown in Figure 6, it is possible to indicate the MCS for each stream using a total of 18 bits, consisting of 2 bits for MCS Group and 16 bits for MCS Set. Therefore, it is possible to use different MCSs for each stream while suppressing an increase in preamble overhead. The specific mechanism will be explained below with reference to Figure 6 and subsequent figures. Note that if communication can be performed satisfactorily using a common MCS for all streams, the AP (101) can set EMCS to "0" and perform single-user MIMO by indicating the previous MCS common to all streams without applying the concept of grouping.

[0055] FIG. 6 shows the setting table 1 (600) for the MCS Group (501). Communication is performed by changing the MCS for each stream, but the communication targets are the same device, so a significant difference in propagation loss is unlikely to occur. For example, the required SNR difference between 1024QAM and BPSK is 20 dB or more, and it is extremely unlikely that a difference in propagation loss of 20 dB or more will occur between antennas in the same device. In other words, the possibility (need) of simultaneously setting an MCS corresponding to 1024QAM and an MCS corresponding to BPSK in the same device is extremely low. For this reason, group setting is divided into four groups based on the MCS closest to the required SNR for the desired communication, and an MCS Group is assigned to each user. The MCS for each stream is selected and set from among these groups. Setting from the MCS within a group is performed in the MCS Set (601), and the MCS Set is set in the Special User Info field (402). For example, if the MCS Group (501) is 10 and the MCS Set (601) is 10, then 1024QAM, coding rate 3 / 4, and MCS=10 are selected.

[0056] The MCS Set for each stream is set in the Special User Info field (402). FIG. 7 shows an example of MCS Set settings. This example assumes that the maximum number of streams assigned during single-user MIMO communication is "8," but this is merely an example. For example, it is also possible to extend the maximum number of streams to a number such as "16." Even in this case, by extending the Special User Info field (402) to the number of bits corresponding to the number of streams, it is possible to customize the MCS for each stream even when performing MIMO with a total of 16 streams. For example, if the maximum number of streams is "16," the MCS Set can be extended to 36 bits. Note that, while FIGS. 3 to 6 illustrate a case in which an AP (101) performs single-user MIMO communication with a STA such as STA (102), the present invention is not limited to this example. Customization for each stream can also be performed when the STA (102) performs single-user MIMO communication toward an AP such as the AP (101). In this case, the roles of the soundings shown in (306) to (308) are reversed. In other words, the STA (102) starts a sounding protocol sequence and transmits a sounding NDP to the AP (101). The AP (101) that receives the sounding NDP transmits a CQI (Channel Quality Indication) calculated based on the sounding NDP to the STA (102). The STA (102) then sets an MCS for each stream based on the received CQI, etc., and transmits a data frame for single-user MIMO communication toward the AP (101).

[0057] Next, Figure 8 shows an example of the configuration (800) of a preamble signal and data when an AP such as the communication device 101 performs multi-user MIMO communication for multiple STAs. This is common to single-user communication, and overlapping content will be omitted as appropriate, with only differences explained. In multi-user MIMO communication, the MCS for each stream is also notified in UHR-SIG. UHR-SIG1 (801) is composed of a Common field (803) and a User Specific field (804). Content related to the MCS setting is notified by a combination of 2Users encoding blocks (805-806) and a Special User Info2 field (802) (an example of first specific information). The 2Users encoding block (805-806) stores User fields for two users. The Special User Info2 field (802) is placed after the User field that stores unique information for each user who is the other end of the MIMO communication. For example, when the AP (101) performs MU communication with five STAs, five User fields and one Special User Info2 field are transmitted as the User Specific field (804). In this embodiment, it is assumed that one user encoding block in the UHR-SIG is composed of 54 bits. 8, one user encoding block may store two user fields, or may store one user field and one Special User Info2 field. In the latter case, one user field may be placed in B0 to B21, and the Special User Info2 field may be placed in B21 to B36. In addition, information for each user may be transmitted using 805, 806, etc., and the last user encoding block may contain only the Special User Info2 field.In this case, the last user encoding block does not have a User field, but has a Special User Info2 field in B0 to B15, with the following fields B16 to B41 being padding fields.

[0058] 9 shows examples (variations) of the contents of the 2 users encoding block (805). The contents related to the MCS for each stream are specified in the subfields of the User fields (900) for each of the two users. The User fields B0-B21 store unique information for User A, and the User fields B22-B43 store unique information for User B, which is different from User A. Specifically, the MCS Group (901) indicates the group of MCSs that the corresponding user should use, as in single-user MIMO communication. The number of streams in communication is set in the Spatial Configuration (902). The Spatial Configuration (902) stores the total number of streams and information specifying which streams are assigned to each user.

[0059] In the example shown in FIG. 9, the MCS Group (901) and Spatial Configuration (902) for each user are set separately.

[0060] An example of Spatial Configuration (902) is shown in Figure 10. Nuser (1000) indicates the number of users. Furthermore, Nss1 indicates the number of streams of the first user, which corresponds to the 1st 2users encoding block (805), and Nss2 indicates the number of streams of the second user, which corresponds to the 2nd 2users encoding block (806). In this example, the total number of streams is limited to a maximum of 8, and Nuser is a maximum of 8. When Nuser is 8, the number of streams assigned to each user is 1. In the example of Figure 10, the maximum number of streams assigned per user is 4. The Nuser number is derived by counting how many 22-bit User fields are stored in the UHR-SIG shown in Figure 9. For example, if five User fields are stored for UHR-SIG, it can be determined that Nuser is 5.

[0061] The MCS Group (901) in multi-user communication is the same as that in Setting Table 1 (600) shown in FIG. 6 . Also, when EMCS is set to "0," the same MCS is used for all streams directed to that user using the previous MCS indication method for each user. The difference from single-user MIMO communication is as follows: The user fields (8071, 8072, ...) for each user are transmitted first, and then a Special User Info2 field (802) indicating the MCS set is provided at the end of the user fields (8071, 8072, ...). Specifically, instead of transmitting the Special User Info2 field (802) immediately after the user fields (8071, 8072, ...) for each user, the Special User Info2 field (802) is transmitted as follows: That is, they are commonly transmitted together after the user fields (8071, 8072, ...) for all users. Each of the user fields 8071, 8072, ... contains information for two users. Therefore, the number of user fields 8071, 8072, ... is N / 2, where N is the total number of users. If the total number of users N is odd, the Special User Info field (802) may contain information for one additional user. In other words, if the total number of users N is odd, the Special User Info2 field (802) in FIG. 8 contains information B0 to B21 shown in the "User field" in FIG. 9 in addition to the information shown in FIG. 11. On the other hand, if the total number of users N is an even number, the Special User Info2 field (802) contains only the information shown in FIG. 11, and does not contain the information B0 to B21 shown in the "User field" in FIG.

[0062] FIG. 11 shows an example of the Special User Info2 field (802). The MCS for each stream is similar to that in single-user MIMO communication. Specifically, the MCS for each stream is indicated based on a combination (an example of first specific information) of MCS Group information and MCS Set (601) information indicated in the Special User Info2 field (802). The value range that can be set in the MCS Set (601) and its meaning are the same as those in single-user communication. In this embodiment, as described above, it is assumed that the maximum number of streams per user is four. A communication device such as an AP specifies the number of streams used for data transmission to each user (each STA) using the value of Spatial Configuration, the number of users with whom simultaneous communication is performed, and the order of the user fields. For example, in MU-MIMO communication for three users, if "001100" is set in the Spatial Configuration field, the following occurs: Four streams are assigned to the user (STA) identified in the first user field, and two streams are assigned to the user (STA) identified in the second user field. Then, two streams are assigned to the user (STA) identified in the third user field. Each STA (102 to 104) determines which User field its STA-ID is included in. Furthermore, it determines how many streams are assigned to users before itself and how many streams are assigned to itself based on the value of the Spatial Configuration field and the number of users. Using this information, it determines which MCSSet in Special User Info2 to refer to. For example, the STA (e.g., 102) corresponding to the second user field in the above example recognizes that four streams have been assigned to the previous STA and two streams have been assigned to itself. It then obtains the values ​​stored in the Stream 5 MCS Set and the Stream 6 MCS Set and derives the MCS corresponding to the MCS Group assigned to itself.The STA corresponding to the second user field reads from the preamble that the data of each stream is transmitted using the derived MCS, and then appropriately changes the operating parameters of the antenna and decoder to receive the data using that MCS. This configuration change enables the STA to appropriately receive and decode the data of each stream transmitted using a different MCS.

[0063] Similarly, a method for setting an MCS for each stream when performing trigger-based multi-user MIMO communication is shown. Figure 12 shows a sequence diagram of trigger-based communication. Note that Figure 13 shows the sequence when performing UL multi-user MIMO, since this is trigger-based communication. STA (102) (the same applies to STAs (103, 104), hereinafter) transmits a probe request (1200) to AP (101), and AP (101) responds to STA (102) with a probe response (1201). Having received the probe response (1201), STA (102) transmits an authentication request (1202) to AP (101), and AP (101) responds to STA (102) with an authentication response (1203). Upon receiving the authentication response (1203), the STA (102) transmits a connection request (1204) to the AP (101), and the AP (101) responds with a connection response (1205). The AP (101) that transmitted the connection response (1205) starts a sounding protocol sequence (1206) and transmits a sounding NDP (1207) to the STA (102). Upon receiving the sounding NDP (1207), the STA (102) transmits a CQI (1208) calculated based on the sounding NDP (1207) to the AP (101). This CQI (1208) is the result of SNR calculation. The AP (101) sets an MCS (1209) based on the CQI calculation result. The MCS at this time is set for each stream based on the CQI for each stream, and the AP (101) notifies the STA (102) in a trigger frame (1210). The STA (102) sets an MCS for each stream based on the content notified in the trigger frame (1210), and transmits a data frame (1211). The data frame transmitted from the STA (102) is also called a TB (Trigger-Based) PPDU (Physical layer (PHY) Protocol Data Unit).

[0064] 13 shows the structure of a trigger frame (1300). Notification of the MCS and number of streams to the user is shown in User Info (1301).

[0065] The number of streams is set in two subfields, Starting Spatial Stream (1305) and Number of Spatial Streams (1306) in User Info (1301). The MCS is set by a combination of two subfields (an example of first specific information), MCS Group (1302) and UL UHR MCS (1303) in User Info (1301). The MCS is set based on the MCS setting table shown in FIG. 6. From the group set in MCS Group (1302), an MCS set (1307) for each stream is set in UL UHR MCS (1303) to determine the MCS of the data frame. For example, if the MCS Group (1302) is "10" and the MCS Set (1307) of the UL UHR MCS (1303) is "10", then an MCS of 10 with a modulation scheme of 1024QAM and a coding rate of 3 / 4 is selected. The MCS Set (1307) is set according to the number of Spatial Streams (1306). The example in Fig. 13 shows an example in which the maximum number of streams per user is 4.

[0066] The Starting Spatial Stream subfield (1305) indicates the starting spatial stream, and stores a value obtained by subtracting 1 from the Starting Spatial Stream.

[0067] The Number Of Spatial Streams subfield (1306) indicates the number of spatial streams, and stores a value obtained by subtracting 1 from the number of spatial streams.

[0068] For example, if the number of spatial streams is 4 and the numbers of the spatial streams are represented by streams 1 to 4, the following settings are made: the Starting Spatial Stream subfield (1305) is set to 0, and the Number Of Spatial Streams subfield (1306) is set to 4.

[0069] In this case, each STA (102 to 104) identifies the location of the RU to be used by itself based on the value included in the RU Allocation subfield (1309). Then, when transmitting data using the RU, the STA (102 to 104) identifies the following based on the subfields (1305) and (1306) of the SS (Spatial Stream) Allocation subfield (1309). That is, the STA (102 to 104) identifies the number of spatial streams allocated to itself and the spatial streams to be used (spatially independent transmission paths to be used). Then, each STA (102 to 104) controls itself to transmit data using one or more spatial streams allocated to itself by the AP (101).

[0070] IEEE 802.11be defines up to 16 MCSs, and if the number of streams in trigger-based communication is a maximum of four, 16 bits are required to set MCS 1 to 16. By grouping in the same way as the method shown in Figure 6, it becomes possible to indicate MCS Group with 2 bits and MCS Set with 8 bits, for a total of 10 bits, which also has the advantage of reducing the overhead of the trigger frame.

[0071] 12 and 13, a subfield (an example of second specific information) corresponding to the above-mentioned EMCS subfield may be incorporated into the Common Info (1308) of the trigger frame (1300). In this case, the EMCS subfield similarly indicates whether or not an individual MCS is applied to each stream. When "0" is set, a common MCS is used for all streams, as in the previous standard 802.11bn. When "1" is set, it indicates that an individual MCS is applied to each stream, which is a feature of this embodiment.

[0072] (Modification) In the above-described embodiment, an MCS group is designated as a reference for all streams transmitted between terminals, and an MCS for each stream is determined using the reference MCS group and an MCS set for each stream. The MCS set for each stream is shown in setting table 1 described with reference to Fig. 6. MCS Group setting table 1 (600) in Fig. 6 is designed based on the technical idea of ​​grouping MCSs with similar required SNRs.

[0073] However, modifications can also be made to use other concepts as the grouping criteria. FIG. 14 shows an example of MCS Group setting table 2 (1400) used in a modified example instead of setting table 1. The major difference between FIG. 6 and FIG. 14 is that the coding rate for each group is common. Common coding rate for each group means that the QAM corresponding to the data density superimposed on one symbol is changed for each stream, but the coding rate for error correction is not changed. By configuring the coding rate for each stream to be fixed and only the QAM to be different for each stream, as in this modified example, there is no need to configure different hardware for error correction in the subsequent stage for each stream. This has the added advantage of enabling MIMO communication by selecting a QAM suitable for each propagation path while reducing hardware implementation costs. As with setting table 1 (600), MCS Group is represented by four, using two bits. The grouping function in this modified example is also referred to as UEQM (UnEqual Modulation). Furthermore, the grouping function that customizes both the coding rate and QAM for each stream, as explained in Fig. 6, is called UEQ-MCS (UnEQual MCS). This name is just an example.

[0074] FIG. 14 also illustrates an example in which the MCS set (1401) within a group is represented by three bits. Because the modulation schemes within a group are different, setting an MCS for each stream is advantageous compared to setting table 1 (600) when the required SNR for each stream differs significantly. Note that using three bits increases the overhead for information transmission somewhat. Therefore, even in this modification, it is possible to modify the MCS set to only two bits and four patterns. While this further modification somewhat reduces the degree of freedom in the QAM that can be used for each stream, it makes it possible to share the error correction mechanism in the subsequent stage while balancing the suppression of overhead increases and optimization according to the propagation path.

[0075] Furthermore, capability information indicating whether UEQM or UEQ-MCS is supported can be included in the probe request described in Fig. 3, i.e., Probe Request of the IEEE 802.11 standard, or the probe response, i.e., Probe Response of the IEEE 802.11 standard, etc. Fig. 15 shows an example of the configuration of the capability information to be notified.

[0076] Fields 1501 to 1503 store values ​​for identifying the information element as UHR Capabilities Information. The UHR Capabilities Information contains multiple fields. Specifically, it contains UHR MAC Capabilities Information (not shown) which lists MAC layer capability information. It also contains UHR PHY Capabilities Information field 1504 which lists PHY layer capability information. In this way, the UHR Capabilities Information stores capability information indicating whether or not an AP or STA supporting the IEEE 802.11bn standard supports various optional functions. The UHR PHY Capabilities Information field 1504 will be described in detail. 1504-1 stores capability information indicating whether single-user MIMO and / or downlink MU MIMO are supported. Storing "1" in 1504-1 indicates that the UEQM function can be used when performing single-user MIMO and / or downlink MU MIMO (the UEQM function is supported). Storing "0" in 1504-1 indicates that the UEQM function cannot be used when performing single-user MIMO and downlink MU MIMO (the UEQM function is not supported). Storing "1" in 1504-2 indicates that the UEQM function can be used when performing trigger-based UL MU MIMO. Storing "0" in 1504-2 indicates that the UEQM function cannot be used when performing trigger-based UL MU MIMO. The information shown in Fig. 15 may be configured to be included in a management frame other than a probe request or probe response. For example, the capability information shown in Fig. 15 may be included in a beacon conforming to the IEEE 802.11 standard transmitted by the AP 101 and publicly announced.Also, the capability information may be included in the frames indicated by 302 to 305, i.e., Authentication and Association Request / Association Response of the IEEE 802.11 standard. By including the capability information shown in Fig. 15 in these management frames, it is possible to transmit capability information indicating whether or not the device supports UEQM to the other device in advance. Note that the capability information may also be transmitted in other management frames or action frames.

[0077] The AP (101) or STA (102) that receives the capability information of the other device through the above-mentioned frame communication stores the capability information of the other device as an operating parameter. Then, when the AP (101) or STA (102) attempts to perform single-user MIMO communication or multi-user MIMO communication with the other device, it references the operating parameter and determines whether the other device supports UEQM. Based on this determination, the AP (101) or STA (102) may decide whether to communicate using the grouping concept described in the above-mentioned embodiment. When sending data to a communication device that does not support the UEQM function, the grouping concept may not be applied, and the MCS common to all streams, as exemplified in 503, may be notified in the preamble, and data communication may be performed using the MCS common to all streams. Furthermore, when sending data to a communication device that supports the UEQM function, the grouping concept may be applied, and the QAM used for each stream may be customized to perform data communication.

[0078] Note that, while FIG. 15 illustrates the UEQM capability notification described in the modified example as an example, when the UEQ-MCS function is used, the capability information may be configured as follows. Specifically, the capability information may be configured to include information indicating whether or not the UEQ-MCS function is supported, and may be notified to the other device via a management frame or publicly announced via a beacon. In this case, too, it is possible to configure the capability information to indicate whether or not the UEQ-MCS function is supported in the case of single-user MIMO and / or downlink MU MIMO, and whether or not the UEQ-MCS function is supported when performing trigger-based UL MIMOMU MIMO, as separate pieces of capability information. Note that the names of the fields for notifying the capability information and the bit values ​​stored therein are merely examples. In other words, the capability information may be configured to indicate to the outside whether or not the function of applying different QAMs and MCSs to streams for the same communication partner is supported, and it goes without saying that the specific transmission method may be modified.

[0079] Other Embodiments The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., an ASIC or FPGA) that realizes one or more functions.

[0080] Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0081] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0082] This application claims priority based on Japanese Patent Application No. 2024-134597, filed August 9, 2024, the entire contents of which are incorporated herein by reference.

[0083] 101 AP 102-104 STA

Claims

1. A communication device comprising: a transmitting means for transmitting an MU (Multi-User) PPDU (Physical Layer Protocol Data Unit) including a U-SIG (Universal Signal field) and a specific SIG following the U-SIG in its preamble; wherein the specific SIG includes control information for specifying an MCS (Modulation and Coding Scheme) that is a modulation method and coding rate for a data portion of each of a plurality of streams, the control information being directed to one or more specific communication devices; and wherein the control information can include first specification information, the first specification information indicating that a data portion of a first stream of the plurality of streams is modulated and coded using a first MCS, and that a data portion of a second stream of the plurality of streams is modulated and coded using a second MCS; The communication device, wherein the second MCS is different from the first MCS.

2. A communication device having an access point function, comprising: a transmitting means for transmitting a trigger frame to each of a plurality of STAs (STAtions); and a receiving means for receiving Trigger-Based (TB) PPDUs (Physical layer (PHY) Protocol Data Units) transmitted in a plurality of streams from the plurality of STAs, wherein the trigger frame includes control information for specifying a Modulation and Coding Scheme (MCS), which is a modulation method and coding rate for a data portion of each of the plurality of streams, and the control information can include first specification information. The first specification information indicates that a data portion of a first stream to be transmitted by a specific STA among the plurality of streams should be modulated and encoded using a first MCS, and indicates that a data portion of a second stream to be transmitted by the specific STA among the plurality of streams should be modulated and encoded using a second MCS, and the second MCS is different from the first MCS.

3. The communication device according to claim 1 or 2, characterized in that the control information can further include second specific information, and the second specific information indicates whether modulation and coding are used with a common MCS for the data portions of the multiple streams.

4. The communication device described in claim 3, characterized in that the second identification information is binary information that selectively includes either a first value indicating that the data portion of each of the multiple streams is modulated and coded using an individual MCS, or a second value indicating that the data portion of the multiple streams is modulated and coded using a common MCS, and the first identification information is included in the control information when the second identification information indicates the first value.

5. A communication device according to any one of claims 1 to 4, characterized in that the first specific information is specific information indicated by combining information stored in the first subfield and information stored in the second subfield.

6. The communication device according to claim 5, wherein the first MCS and the second MCS are combinations of different modulation methods but a common coding rate.

7. A communication device according to claim 5 or 6, wherein the first subfield and the second subfield are not adjacent to each other.

8. A communication device as described in any one of claims 5 to 7, characterized in that the information stored in the first subfield is used to specify a common coding rate to be used in at least each stream, and the information stored in the second subfield is used to specify an individual modulation method to be used in each stream.

9. A communication device according to any one of claims 1 to 8, further comprising a determination means for determining said control information based on past communication records or sounding results.

10. The communication device according to claim 1, which performs multi-user MIMO (Multi-Input-Multi-Output) communication, and wherein the specific SIG includes the first subfield for each of a plurality of the specific communication devices.

11. The communication device according to claim 10, wherein the specific SIG includes the second subfield that is common to a plurality of the specific communication devices.

12. A communications device having a STA (STAtion) function, comprising: a receiving means for receiving an MU (Multi-User) PPDU (Physical Layer Protocol Data Unit) including a U-SIG (Universal Signal field) and a specific SIG following the U-SIG in its preamble; and a demodulating means for demodulating a data portion of the received MU PPDU based on the specific SIG, wherein the specific SIG includes control information for specifying an MCS (Modulation and Coding Scheme), which is a modulation method and coding rate for each data portion of a plurality of streams, and the control information is directed to one or more specific STAs including the communications device itself; and the control information includes first specification information. The first specification information indicates that a data portion of a first stream among the plurality of streams is modulated and encoded using a first MCS, and that a data portion of a second stream among the plurality of streams is modulated and encoded using a second MCS, and the second MCS is different from the first MCS.

13. A communication device according to any one of claims 1 to 12, characterized in that the transmitting means further transmits to the outside a management frame including capability information indicating to the outside whether or not the device supports a function for communication by applying different modulation methods, or different modulation methods and coding rates, to streams for the same communication partner.

14. A communications device characterized by having a communications means for communicating a management frame conforming to the IEEE 802.11 standard, which includes capability information indicating to the outside whether or not the device supports a function for applying different modulation methods, or different modulation methods and coding rates, to each of the multiple streams when communicating multiple streams to the same communications partner.

15. A control method for controlling communications, comprising: a transmitting step of transmitting an MU (Multi-User) PPDU (Physical Layer Protocol Data Unit) including a U-SIG (Universal Signal field) and a specific SIG following the U-SIG in its preamble; wherein the specific SIG includes control information for specifying an MCS (Modulation and Coding Scheme) that is a modulation method and coding rate for a data portion of each of a plurality of streams, the control information being directed to one or more specific communications devices; and wherein the control information can include first specification information, the first specification information indicating that a data portion of a first stream of the plurality of streams is modulated and coded using a first MCS, and that a data portion of a second stream of the plurality of streams is modulated and coded using a second MCS; The method of claim 1, wherein the second MCS is different from the first MCS.

16. A control method for controlling communications, comprising a communication control step of communicating a management frame conforming to the IEEE 802.11 standard, which includes capability information indicating to the outside whether or not a function is supported for communication by applying different modulation methods, or different modulation methods and coding rates, to each of the multiple streams when communicating multiple streams to the same communication partner.

17. A program for causing a computer to function as the communication device control method according to claim 15 or 16.

Images