Communication device and communication method

Abstract

A communication apparatus that achieves high efficiency of carrier aggregation is provided. The communication apparatus according to the present invention is provided with: a communication section that transmits and receives radio signals by using a first communication band and a second communication band; and a control section that controls a communication operation in the communication section, wherein the control section performs control so that a signal including information about unused channels in the second communication band is transmitted by using a channel of the first communication band. The control section also performs control so that data is transmitted to a transmission destination of the signal by using one of a plurality of unused channels of the second communication band included in the signal.

Description

Technical Field

[0001] The technology disclosed herein relates to a communication device and a communication method for transmitting and receiving radio signals. Background Art

[0002] Increasing data capacity and improving peak throughput in wireless local area networks (LANs) are necessary to cope with the recent increase in requested data traffic. Carrier aggregation, which simultaneously uses multiple frequency bands for communication, has attracted attention as a method for increasing data capacity and improving peak throughput in wireless LANs. Carrier aggregation is expected to be standardized in the next generation of the IEEE 802.11 standard.

[0003] In the case of channel access using carrier sense multiple access with collision avoidance (CSMA / CA) currently applied, carrier sense is performed for the primary channel (hereinafter also referred to as "PCH") of each frequency band. Unless it is determined that no communication using the PCH of each frequency band is being performed (hereinafter also referred to as "idle" or "in an idle state"), communication using carrier aggregation is not allowed to start. In other words, when the PCH of a certain frequency band is idle but the PCH of another frequency band is not idle, it is necessary for the transmitting terminal to wait until all PCHs become idle. This results in overhead due to waiting for transmission and thus leads to a decrease in communication efficiency.

[0004] In addition, a wireless communication device has been proposed that uses statistical data to perform timely communication when a corresponding channel becomes idle (for example, refer to Patent Document 1). This may result in a significant increase in the amount of processing performed by the transmitting terminal.

[0005] Reference List

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-28746 Summary of the Invention

[0008] Technical issues

[0009] One object of the technology disclosed herein is to provide a communication apparatus and a communication method for performing channel access using CSMA / CA.

[0010] Solution to the problem

[0011] The technology disclosed herein has been achieved in view of the above-mentioned problems, and a first aspect of the technology disclosed herein is a communication device including

[0012] a communication unit that transmits and receives radio signals using the first communication frequency band and the second communication frequency band; and

[0013] A controller controls a communication operation performed by the communication section, the controller performing control so that a signal including information on a clear channel in a second communication frequency band is transmitted using a channel in the first communication frequency band.

[0014] In addition, the controller performs control so that data is transmitted to the transmission destination of the signal using one of a plurality of idle channels of the second communication frequency band, the plurality of idle channels of the second communication frequency band being included in the signal.

[0015] In addition, the controller performs control so that data is transmitted using a channel designated by a response signal from a transmission destination of the signal, the designated channel being from among the plurality of idle channels included in the signal.

[0016] In addition, a second aspect of the technology disclosed herein is a communication method for performing wireless communication using a first communication frequency band and a second communication frequency band, the communication method including:

[0017] using a channel of the first communication frequency band to transmit a signal including information about an idle channel in the second communication frequency band; and

[0018] Data is transmitted to a transmission destination of the signal using an idle channel included in the signal.

[0019] In addition, a third aspect of the technology disclosed herein is a communication device, including:

[0020] a communication unit that transmits and receives radio signals using the first communication frequency band and the second communication frequency band; and

[0021] A controller controls a communication operation performed by the communication section, the controller performing control so that a signal including information on an idle channel in a second communication frequency band is received using a channel in the first communication frequency band.

[0022] The controller performs control so that a reception operation is performed using one of a plurality of idle channels included in the signal addressed to the communication device.

[0023] In addition, the controller performs control so that a response signal including information about a channel selected from a plurality of idle channels included in the signal addressed to the communication device is returned, and the controller performs control so that a receiving operation is performed using the channel included in the response signal.

[0024] In addition, a fourth aspect of the technology disclosed herein is a communication method for performing wireless communication using a first communication frequency band and a second communication frequency band, the communication method including:

[0025] receiving a signal including information about an idle channel in a second communication frequency band using a channel of the first communication frequency band; and

[0026] Based on the information included in the signal, transmission and reception of data performed using the second communication frequency band are controlled.

[0027] Advantageous Effects of the Invention

[0028] The technology disclosed herein makes it possible to provide a communication device and a communication method that achieve high efficiency of carrier aggregation in accordance with a channel access scheme using CSMA / CA.

[0029] Note that the effects described herein are merely exemplary, and the effects provided by the present disclosure are not limited thereto. In addition to the effects described above, the present disclosure may also provide additional effects.

[0030] Other objects, features, and advantages of the technology disclosed herein will be apparent from more detailed description based on the following embodiments and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] [ Figure 1 ] Figure 1 An example of a configuration of a communication system is schematically shown.

[0032] [ Figure 2 ] Figure 2 An example of the functional configuration of the communication device 200 is shown.

[0033] [ Figure 3 ] Figure 3 An example of an operation performed when data transmission is performed using carrier aggregation by using two communication bands of Band A and Band B is shown, the operation being performed for each communication band.

[0034] [ Figure 4 ] Figure 4 An example of a communication sequence performed by applying the technology proposed herein is shown (first embodiment).

[0035] [ Figure 5 ] Figure 5 Examples of the formats of the CA Pre-Request frame and the CA Pre-Response frame are shown.

[0036] [ Figure 6 ] Figure 6 This is a flowchart of the detailed process of the confirmation processing sent by CA.

[0037] [ Figure 7 ] Figure 7 This is a flowchart of the detailed process of preparing for CA reception and NAV setting.

[0038] [ Figure 8 ] Figure 8 This is a flowchart of the detailed process of preparing for CA transmission and processing NAV setting.

[0039] [ Figure 9 ] Figure 9 An example of the operation of each communication band when data is transmitted using carrier aggregation by using two communication bands of Band A and Band B is shown (first embodiment).

[0040] [ Figure 10 ] Figure 10 An example of a communication sequence performed by applying the technology proposed herein is shown (second embodiment).

[0041] [ Figure 11 ] Figure 11 An example of the format of the CA pre-notification frame is shown.

[0042] [ Figure 12 ] Figure 12 It is a flowchart of the detailed process of preparing for CA transmission.

[0043] [ Figure 13 ] Figure 13 This is a flowchart of the detailed process of preparing for CA reception and NAV setting.

[0044] [ Figure 14 ] Figure 14 An example of the functional configuration of the communication device 1400 is shown.

[0045] [ Figure 15 ] Figure 15 An example is shown in which transmission is performed using the communication band which is band A.

[0046] [ Figure 16 ] Figure 16 An example is shown in which transmission is performed using two communication bands, Band A and Band B.

[0047] [ Figure 17 ] Figure 17 Shown is the arrangement of frequency channels that can be used in a wireless LAN system. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the technology disclosed herein will be described in detail with reference to the accompanying drawings.

[0049] Figure 17 The arrangement of frequency channels that can be used in a wireless LAN system is shown. Here, the diagram shows the channel arrangement in the currently available 5 GHz frequency band.

[0050] exist Figure 17The uppermost portion of FIG shows a configuration in which one channel is used per 20 MHz, where channels 36, 40, 44, 48, 52, 56, 60, and 64 are arranged in order from low frequency to high frequency. Channels 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, and 144 are arranged relative to higher frequencies.

[0051] In addition, Figure 17 The second portion from the top shows a configuration using one channel per 40 MHz, where channels 38, 46, 54, and 62 are arranged in order from low frequency to high frequency. Channels 102, 110, 118, 126, 134, and 142 are arranged relative to higher frequencies.

[0052] In addition, Figure 17 The third portion from the top of FIG. 1 shows a configuration in which one channel is used per 80 MHz, where channels 42 and 58 are arranged in order from low frequency to high frequency. Channels 106, 122, and 138 are arranged with respect to higher frequencies.

[0053] In addition, Figure 17 The fourth portion from the top in FIG. 1 shows a configuration in which one channel is used per 160 MHz, in which channel 50 is arranged. Channel 114 is arranged relative to a higher frequency.

[0054] Notice, Figure 17 The range of available frequency channels shown may vary by country, as legally permitted frequency channels vary by country. Furthermore, the channel arrangement also applies to frequency bands other than the aforementioned (e.g., the 2.4-GHz band) and frequency bands that are being newly used (or license-exempt) (e.g., the 6-GHz band). The channel arrangement also applies to combinations of these different frequency bands.

[0055] The following description assumes a communication system in which, for example, two frequency bands, the 2.4-GHz band and the 5-GHz band (or the 6-GHz band) (hereinafter also referred to as "communication bands"), are used simultaneously. When comparing the 2.4-GHz band with the 5-GHz or 6-GHz band, it can be said that the 5-GHz or 6-GHz communication band, which is a higher frequency band, is suitable for transmitting large amounts of data.

[0056] like Figure 17 As shown, each communication frequency band includes multiple channels. Typically, a primary channel (PCH) primarily used in wireless communications is determined for each communication frequency band in the network (such as a basic service set (BSS)). When a communication terminal performs channel access using CSMA / CA in a certain communication frequency band, the communication terminal performs carrier sensing on the PCH of the specific communication frequency band.

[0057] Taking into account that one channel is used for every 20 MHz, and by making the communication band wider, a maximum of one channel can be used for every 160 MHz, it is assumed that even when the communication terminal uses one channel for every 20 MHz, the communication terminal can perform carrier sensing within the 160-MHz range including the PCH. In addition, when one channel is used for every 20 MHz, the channel within the 160-MHz carrier sensing range including the PCH and on which carrier sensing is performed at the same time (that is, the channel other than the PCH and on which carrier sensing is performed) will also be referred to as the secondary channel (SCH) hereinafter. When carrier sensing is performed on the PCH of a certain communication band, the result of performing carrier sensing on the SCH is also obtained at the same time. Similarly, when one channel is used for every 40 MHz or every 80 MHz, the channel other than the PCH and on which carrier sensing is performed is the SCH.

[0058] Figure 1 An example of a configuration of a communication system to which the technology disclosed herein is applied is schematically shown. It is assumed that the communication system shown includes a plurality of stations (STA: slave stations).

[0059] Assume that when STA1 and STA2 transmit data to each other, they can simultaneously use the communication band as A band and the communication band as B band, that is, they can perform communication using carrier aggregation. The A band and the B band each include a primary channel (PCH).

[0060] Here, the A band and the B band refer to, for example, the 920-MHz band, the 2.4-GHz band, and the 5-GHz band, which are currently designated as unlicensed bands, and the 6-GHz band, which is expected to be designated as an unlicensed band in the future. There are no particular restrictions on the combination of each band. In addition, carrier aggregation using at least two communication bands can be performed between STA1 and STA2.

[0061] On the other hand, STA3 is another STA located within the reach of signals from STA1 and STA2. STA3 may belong to the same BSS as STA1 and STA2, or may belong to another BSS.

[0062] Note that the configuration of the communication system to which the technology disclosed herein is applied is not limited to Figure 1 The configuration shown. It is sufficient if there are multiple communication devices with which a connection is established, and one of the multiple communication devices is a surrounding terminal of another of the multiple communication devices. As long as the above conditions are met, any positional relationship can be adopted. In addition, one of STA1 and STA2 can be an access point (AP: base station), although this is not specifically described in this document.

[0063] Figure 2An example of the functional configuration of the communication apparatus 200 operating as an STA (including an AP) is shown. Each component included in the communication apparatus 200 is described below.

[0064] The communication controller 201 controls the overall operation of the communication device 200. In addition, the communication controller 201 performs processing for transferring control information notified to another communication terminal to the data processor 202. In this embodiment, the communication controller 201 performs selection and switching of transmission / reception channels in the wireless communication units 206 and 207 in order to perform communication using carrier aggregation, and the communication controller 201 generates and acquires a signal including information about the channels used for carrier aggregation.

[0065] Data processor 202 generates a transmission signal mainly based on transmission data from an upper layer and control information received from communication controller 201. In addition, data processor 202 demodulates reception signals received from wireless communication sections 206 and 207 to perform processing for extracting reception data and control information.

[0066] The communication device 200 according to the present embodiment is a communication terminal that performs communication using carrier aggregation by using two communication bands, Band A and Band B. Figure 2 As shown, the data processor 202 includes a shared data processor 203 in the medium access control (MAC) layer, and includes separate data processors in the PHY layer, which are a data processor 204 for frequency band A and a data processor 205 for frequency band B. The reason is that such a configuration makes it possible to perform communications in multiple communication frequency bands at the same time and to perform overall data management (such as management of sequence numbers) collectively.

[0067] Wireless communication sections 206 and 207 perform analog conversion and radio frequency (RF) processing on the transmission signal generated by data processor 202 to generate radio signals that are output from antennas 208 and 209, respectively. Furthermore, wireless communication sections 206 and 207 perform RF processing and digital conversion on the radio signals input to antennas 208 and 209, respectively, to generate received signals, and pass the generated received signals to data processor 202. One of the wireless communication sections (wireless communication section 206) performs processing on radio signals using frequency band A, and the other of the wireless communication sections (wireless communication section 207) performs processing on radio signals using frequency band B.

[0068] Note that when multiple-input multiple-output (MIMO) communication is performed using frequency band A and MIMO communication is performed using frequency band B, wireless communication sections 206 and 207 each include multiple antennas, and PHY layer data processors 204 and 205 each perform spatial multiplexing processing and spatial separation processing.

[0069] Figure 3 An example of the operation performed when a transmitting terminal transmits data using carrier aggregation using two communication bands, Band A and Band B, is shown. This operation is performed for each communication band. In this case, it is assumed that only the primary channel (PCH) is used for communication performed in each communication band.

[0070] For example, it is assumed that a transmitting terminal performs backoff on the PCH of frequency band A and obtains the transmission right at time T301. Here, when the transmitting terminal attempts to perform carrier aggregation transmission using a channel of frequency band B, and when another communication is being performed using the PCH of frequency band B (hereinafter also referred to as "busy" or "in a busy state"), as shown in FIG. Figure 3 As shown, the transmitting terminal is not allowed to start performing carrier aggregation transmission at this time.

[0071] In these cases, the transmitting terminal can only wait for data transmission until the transmitting terminal regains the transmission right in the B-band, or give up using carrier aggregation and use only the A-band to transmit data.

[0072] In the former method, there is an increase in overhead due to wasted time waiting for transmission, and this leads to a decrease in the efficiency of carrier aggregation communication, and thus makes it difficult to obtain the effect of improving throughput. Figure 3 In the example shown, the PCH of band B is no longer busy at time T302, backoff is restarted to acquire the transmission right at time T303, and then data transmission (data Tx) using carrier aggregation is started using the corresponding PCHs of bands A and B. Therefore, from time T301 when the transmission right is acquired on the PCH of band A to time T303 when the backoff is terminated on the PCH of band B, the transmitting terminal must wait to transmit on the PCH of band A.

[0073] On the other hand, in the latter method, there is a reduction in transmission opportunities using carrier aggregation. In particular, in a congested environment where a large number of terminals exist, there is a possibility that transmission using carrier aggregation will not be performed at all.

[0074] Therefore, a technology is proposed below in this article, which minimizes the overhead caused by waiting to transmit to improve the throughput in the wireless LAN and increase the transmission opportunities using carrier aggregation. The technology proposed in this article enables a communication terminal to dynamically select an idle channel in a certain communication frequency band when the communication terminal obtains the transmission right in another communication frequency band, and perform carrier aggregation communication. When the communication terminal obtains the transmission right on the main channel of one of the communication frequency bands, and when the main channel of another communication frequency band in the communication frequency band is busy, the communication terminal will select an idle secondary channel of the other communication frequency band in the communication frequency band (if such a secondary channel exists), and use the two communication frequency bands to apply carrier aggregation.

[0075] First embodiment

[0076] Figure 4 An example of a communication sequence performed by applying the technology proposed in this article is shown. It is assumed that STA1 is a data transmitting terminal (Tx), STA2 is a data receiving terminal (Rx), and STA3 is another terminal (other) that does not participate in data transmission. In addition, the figure shows a process in which STA1 performs communication using carrier aggregation by using an idle channel of the B band when STA1 obtains the transmission right on the PCH of the A band. In addition, the figure also shows a process in which the surrounding communication terminal STA3 sets a waiting state (network allocation vector: NAV) for at least one of the A band and the B band, and the surrounding communication terminal STA3 communicates with neither STA1 nor STA2.

[0077] First, STA1 and STA2 perform a startup procedure to exchange capability information about their own capabilities and frequency band information to be transmitted (SEQ401). This startup procedure can be performed using the PCH of the A band, or using a channel other than the PCH in the A band or a communication band other than the A band.

[0078] The capability information includes information indicating in which frequency band each of STA1 and STA2 can perform communication, and information about whether transmission and reception using carrier aggregation can be performed. The startup process does not necessarily have to be performed every time carrier aggregation communication is performed. For example, first, a connection between STA1 and STA2 can be established, and then STA1 and STA2 can exchange information when there is a change in their communication status. Assume that Figure 4 In the example of the communication sequence shown, STA1 and STA2 have committed to using carrier aggregation by performing a startup procedure.

[0079] When STA1 obtains the transmission right on the PCH of the A band (SEQ402), STA1 performs a determination process of carrier aggregation (CA) transmission (SEQ403). Specifically, STA1 determines whether the PCH of the B band is idle. When the PCH of the B band has been determined to be not idle, STA1 uses the PCH of the A band to transmit a CA pre-request frame based on the result of the carrier sensing performed by STA1, and the CA pre-request frame indicates at least one idle idle channel other than the PCH in the band B (SEQ404). For example, when STA1 performs carrier sensing on a plurality of channels (secondary channels (SCH)) including the PCH at the same time, at least one idle channel is selected from the SCH. The determination process of CA transmission will be described in detail later (refer to Figure 6 ). In addition, the frame configuration of the CA pre-request frame will be described in detail later (refer to Figure 5 ).

[0080] However, when the PCH of the B band is also idle, STA1 starts to transmit data using carrier aggregation by using the corresponding PCHs of the A band and the B band without any change. Figure 4 In addition, when there is no idle channel in the B band (in the SCH for which carrier sensing has been performed simultaneously with the PCH), STA1 abandons the use of carrier aggregation and uses only the A band to transmit data, or waits for transmission until STA1 also obtains the transmission right in the B band to enable carrier aggregation.

[0081] When STA2 receives a CA pre-request frame addressed to STA2, STA2 performs a process to prepare for CA reception (SEQ405). Specifically, STA2 compares the information about the idle channel list included in the received frame with the result of carrier sensing performed by STA2. STA2 then identifies one of the idle channels included in the list information in the CA pre-request frame and confirmed to be idle based on the result of carrier sensing performed by STA2 as a standby channel for the B-band and switches the channel. Furthermore, when STA3 receives a CA pre-request frame not addressed to STA3 on the PCH of the A-band, STA3 performs NAV setting process 1 for the PCH of the A-band (SEQ406).

[0082] Note that preparation for CA reception and NAV setting processing 1 will be described in detail later (refer to Figure 7 ). In addition, the frame configuration of the CA pre-response frame will be described in detail later (refer to Figure 5 ).

[0083] Thereafter, STA2 uses the PCH of band A to send a CA pre-response frame to STA1, which includes information about STA2's waiting channel (SEQ407). When STA1 receives the CA pre-response frame addressed to STA1 from STA2, STA1 performs a process of preparing for CA transmission (SEQ408). Specifically, STA1 switches the channel of band B to the idle channel (SCH) specified in the channel list information included in the received frame, and prepares for data communication using carrier aggregation. On the other hand, when STA3 receives a CA pre-response frame that is not addressed to STA3, STA3 performs NAV setting processing 2 on the channel of band B given in the received frame (SEQ409). Note that preparations for CA transmission and NAV setting processing 2 will be described in detail later (refer to Figure 8 ).

[0084] Then, STA1 transmits data using carrier aggregation using A-band and B-band (SEQ410 and SEQ411). In response, STA2 returns an acknowledgment (ack) in each of the communication bands, which are A-band and B-band (SEQ412 and SEQ413).

[0085] After the carrier aggregation communication between STA1 and STA2 is completed, as described above, STA1 and STA2 each reset the channel for use in the B band (from the SCH used to perform carrier aggregation communication) to the PCH (SEQ414 and SEQ415) and terminate the process.

[0086] exist Figure 4 In SEQ407, STA2 transmits the CA pre-response frame using only the A-band (PCH). However, for example, the CA pre-response frame can be transmitted using the channel (SCH) used after the B-band channel switch. Therefore, for example, the NAV is set by a terminal belonging to another BSS (other BSS: OBSS), and the channel used after the B-band channel switch is always used. This makes it possible to avoid conflicts in data communications using carrier aggregation.

[0087] Figure 5 An example of the format of a CA Pre-Request frame and a CA Pre-Response frame is shown. The frame format shown is obtained by defining an index of a "Frame Control" field indicating a new frame type with reference to the format of an IEEE 802.11 Action frame.

[0088] “Frame Control” denoted by reference numeral 501 is a field including information indicating the action frame type.

[0089] "Duration" denoted by reference numeral 502 is a field including time information on the time that elapses until the subsequent carrier aggregation communication is completed. A surrounding terminal that is not performing communication reads the value of this field to set NAV.

[0090] The "Receiver Address (RA)" indicated by reference numeral 503 is a field including the MAC address of the transmission destination. Also, the "Sender Address (TA)" indicated by reference numeral 504 is a field including the MAC address of the transmission source.

[0091] The "Request Flag" denoted by reference numeral 505 is a field in which information related to a flag indicating whether the frame is a "CA Pre-Request Frame" or a "CA Pre-Response Frame" is given. For example, when the flag is assigned "1", it indicates that the frame is a CA Pre-Request Frame, and when the flag is assigned "0", it indicates that the frame is a CA Pre-Response Frame.

[0092] “Number of frequency bands” denoted by reference numeral 506 is a field in which the number of communication frequency bands used when carrier aggregation is applied is given.

[0093] The "channel list in frequency band" indicated by reference numeral 507 is a field including information on channels in a certain communication frequency band (used when carrier aggregation is applied). The frame includes the same number of "channel list in frequency band" fields as the number given in the "number of frequency bands" field 506. Figure 5 In FIG. 5 , it is assumed that M is given in the “Number of Bands” field 506 as the number of communication bands.

[0094] "Channel List in Band" field 507 includes a "Band Information" field 511, a "Number of Channels" field 512, and a "Channel Information" field 513. "Band Information" field 511 indicates a communication band, "Number of Channels" field 512 indicates the number of channels in the communication band indicated by "Band Information" field 511, and "Channel Information" field 513 indicates channel information. "Channel List in Band" field 507 includes the same number of "Channel Information" fields 513 as the number indicated in the "Number of Channels" field. The CA pre-request frame includes the same number of "Channel Information" fields 513 as the number of candidate channels for each communication band, while the CA pre-response frame includes only one "Channel Information" field in "Channel List in Band" field 507.

[0095] Specifically, the transmitting terminal that uses carrier aggregation to transmit data provides information about the communication band (B band) used together with the communication band (A band) when carrier aggregation is applied to the "Band Information" field 511 of the CA pre-request frame, and the communication band (A band) is used to transmit the CA pre-request frame. The transmitting terminal provides the number of candidate channels (SCH) confirmed by the transmitting terminal itself as idle in the communication band for applying carrier aggregation to the "Number of Channels" field 512 of the CA pre-request frame. The transmitting terminal provides information indicating a corresponding one of the candidate channels to each "Channel Information" field 513 of the CA pre-request frame. Figure 5 In the embodiment, it is assumed that the communication frequency band includes N candidate channels. On the other hand, the receiving terminal that returns the CA pre-response frame provides the following information to the "Channel Information" field 513 of the CA pre-response frame, which instructs the receiving terminal to select a channel for carrier aggregation from the candidate channels given in the "Channel List in Band" field 507 of the CA pre-request frame.

[0096] Here, the values ​​given in the "Band Information" field 511 and the "Channel Information" field 513 are not particularly limited as long as they are identifiers shared by the communication terminals STA1, STA2, and STA3. For example, the operation class given in Annex E of IEEE 802.11-2016 can be used as "Band Information", and the channel number in the channel set given in Annex E of IEEE 802.11-2016 can be used as "Channel Information".

[0097] A "frame check sequence (FCS)" denoted by reference numeral 508 is a field in which a code for correcting errors in the entire frame is given.

[0098] Figure 6 The detailed process of the determination process of CA transmission is shown in the form of a flowchart. The determination process of CA transmission is performed by STA1 (or by the data transmitting terminal) in Figure 4 The communication sequence shown is executed in SEQ403.

[0099] After STA1 obtains the transmission right on the PCH of the A-band (step S601 ), STA1 checks whether the PCH of the B-band is idle (step S602 ).

[0100] Here, if it is determined that the PCH of the B-band is idle ("Yes" in step S602), STA1 begins communication using carrier aggregation using the PCHs of the A-band and B-band (step S607). In this case, for example, STA1 can perform request-to-send / clear-to-send (RTS / CTS) communication before starting data communication to avoid collisions. Alternatively, both the A-band and the B-band can be widened to start data transmission.

[0101] On the other hand, if it is determined that the PCH of the B-band is busy (No in step S602), STA1 confirms the result of carrier sensing performed on channels other than the PCH in the B-band (step S603). Channels other than the PCH are, for example, the SCH for which STA1 has performed carrier sensing simultaneously with the PCH.

[0102] When STA1 has detected at least one idle channel in the B band ("Yes" in step S604), STA1 generates a CA pre-request frame including the "Channel List in Band" field 507 (refer to Figure 5), and transmits the generated frame to STA2 using the PCH of the A band (step S605). The "Channel List in Band" field 507 includes a "Band Information" field 511, a "Number of Channels" field 512, and a "Channel Information" field 513. The "Band Information" field 511 indicates the B band, the "Number of Channels" field 512 gives the number of channels detected as idle, and the "Channel Information" field 513 gives information about the channels detected as idle. Assuming that the determination in step S604 is Figure 4 "Yes" in the communication sequence shown.

[0103] In addition, when STA1 does not detect an idle channel in the B band ("No" in step S604), STA1 abandons the use of carrier aggregation and starts to perform normal communication using only the PCH of the A band, or waits for data transmission using carrier aggregation until STA1 obtains the transmission right in the B band (step S606).

[0104] Note that there are no restrictions on how STA1, for example, performs carrier sensing. Specifically, for example, according to the method for performing carrier sensing on auxiliary channels defined in IEEE 802.11, a channel in which a constant power level is not detected during the Point Coordination Function (PCF) interframe space (PIFS) (25 microseconds) interval can be detected as idle. Furthermore, when the transmitting terminal includes wireless communication devices for multiple communication frequency bands, different channels can be set for each wireless communication device, and a channel in which a preamble is not detected during the backoff period can be detected as idle.

[0105] In addition, when there are at least three frequency bands used when carrier aggregation is applied, STA1 confirms the result of carrier sensing for each frequency band in step S603, and sends a CA pre-request frame in step S605. The CA pre-request frame includes information about multiple candidate channels for each communication frequency band (that is, including multiple "channel list in frequency band" fields).

[0106] Figure 7 The detailed process of the process of preparing for CA reception and setting NAV is shown in the form of a flowchart. The process of preparing for CA reception and setting NAV is performed by STA2 and STA3 (or by the data receiving terminal and another terminal not participating in data transmission) in Figure 4 The communication sequence shown is performed in SEQ405 and SEQ406.

[0107] When an STA receives a CA pre-request frame transmitted via the A band by another terminal (eg, STA1) intending to transmit data using carrier aggregation (step S701), the STA determines whether the frame is addressed to the STA using the RA field (step S702).

[0108] When it has been determined that the received CA pre-request frame is addressed to the STA (YES in step S702), the process proceeds to the CA reception processing (the STA is STA2 in the example of the communication sequence shown in FIG. 7). In addition, when it has been determined that the received CA pre-request frame is not addressed to the STA (NO in step S702), the process proceeds to the NAV setting processing 1 (the STA is STA3 in the example of the communication sequence shown in FIG. 7). These processes are described below in the above order. Figure 4 Figure 4

[0109] First, the CA reception processing performed by STA2 is described. After STA2 receives the CA pre-request frame addressed to STA2 from STA1 (YES in step S702), STA2 confirms the result of the carrier sensing performed by STA2 on each of the candidate channels included in the "Channel List in Band" field 507 indicating the B band (step S703).

[0110] Here, when at least one of the candidate channels in the "Channel List in Band" field 507 is also detected as idle by STA2 (YES in step S704), STA2 selects a channel for the carrier aggregation communication from among the detected channels, and switches the channel of the B band from the PCH to the selected channel (step S705).

[0111] Then, STA2 transmits a CA pre-response frame including the "Band Information" field 511 in which information on the B band is given and the "Channel Information" field 513 in which information on the selected channel is given to the transmission source of the CA pre-request frame (step S706). Note that because only one channel for the carrier aggregation in the B band is specified in the CA pre-response frame to the CA pre-request frame, only one channel information is included in the "Channel List in Band" field 507 of the CA pre-response frame.

[0112] Thereafter, STA2 waits for reception on the PCH of the A band and the selected channel of the B band (step S707). Assume that the determination in step S704 is YES in the example of the communication sequence shown in FIG. 7. Figure 4

[0113] ​​​On the other hand, if STA2 detects that none of the channels listed in the list are idle ("No" in step S704), STA2 transmits a CA pre-response frame to STA1 that does not include the "Channel List in Band" field 507 indicating the B-band (step S708). In this case, STA1 receives the CA pre-response frame and can detect that the B-band is not permitted for carrier aggregation. Thereafter, STA2 waits for reception only on the PCH of the A-band (step S709).

[0114] Note that in step S705, the method by which STA2 selects a channel for use from a plurality of candidate channels is not particularly limited. For example, the interference and noise levels may be measured while performing carrier sensing, and the channel with the lowest interference and noise levels may be selected. Furthermore, when there are at least three frequency bands used when applying carrier aggregation, STA2 confirms the results of performing carrier sensing on each channel in the list included in the CA pre-request frame from STA1 for each frequency band, selects a channel for each frequency band, and transmits a CA pre-request frame including multiple "Channel List in Band" fields to STA1.

[0115] Next, NAV setting process 1 is described. After STA3 receives a CA pre-request frame not addressed to STA3 from STA1 ("No" in step S702), STA3 reads the information given in the "Duration" field of the frame and sets the NAV for the PCH of the A band (step S710). This allows transmission to be suppressed to avoid collisions in data communication between STA1 and STA2, which is expected to use the PCH of the A band.

[0116] Figure 8 The detailed process of the process of preparing for CA transmission and setting NAV is shown in the form of a flowchart. The process of preparing for CA transmission and setting NAV is performed by STA1 and STA3 (or by the data transmitting terminal and another terminal not participating in data transmission) in Figure 4 The communication sequence shown is performed in SEQ408 and SEQ409.

[0117] When the STA receives the CA pre-response frame transmitted by STA2 through the A-band (step S801), the STA uses the "RA" field to determine whether the frame is addressed to the STA (step S802).

[0118] When it has been determined that the received CA pre-response frame is addressed to the STA ("Yes" in step S802), the process proceeds to the CA transmission process ( Figure 4In the example of the communication sequence shown, the STA is STA1.) In addition, when it has been determined that the received CA pre-response frame is not addressed to the STA ("No" in step S802), the process proceeds to NAV setting processing 2 ( Figure 4 (The example of the communication sequence shown is a case where the STA is STA3.) The following describes these processes in the order described above.

[0119] First, the process of preparing for CA transmission performed by STA1 is described. When STA1 obtains a CA pre-response frame addressed to STA1 from STA2 ("Yes" in step S802), STA1 confirms the "Channel List in Band" field 507 in the frame (step S803).

[0120] Here, when the received CA pre-response frame includes the "Channel List in Band" field 507 indicating the B band ("Yes" in step S803), STA1 switches the channel of the B band to the channel indicated by the "Channel Information" field 513 in the "Channel List in Band" field 507 (step S804). Then, STA1 applies carrier aggregation using the A band and the B band by using the PCH of the A band and the channel of the switched B band, and starts data communication (step S805). Assuming that the determination in step S803 is Yes, Figure 4 "Yes" in the communication sequence shown.

[0121] On the other hand, when the "Channel List in Band" field 507 indicating the B band is not included (No in step S803), STA1 abandons transmitting data using carrier aggregation and starts transmitting data using only the PCH of the A band (step S806).

[0122] Here, when STA1 has acquired information about channels detected as idle in the surrounding environment of the designated channel of the B band, STA1 may transmit data using a wideband channel obtained by integrating the surrounding channels in step S806 .

[0123] When there are at least three frequency bands used when carrier aggregation is applied, STA1 starts data communication using carrier aggregation using only the communication frequency bands included in the corresponding “Channel List in Frequency Band” field 507 .

[0124] Next, we will describe NAV setting process 2. As in the case of NAV setting process 1, when STA3 receives a CA pre-response frame not addressed to STA3 from STA2 (No in step S802), first, STA3 sets NAV for the PCH of the A band based on the information given in the "Duration" in the received frame (step S807).

[0125] Thereafter, STA3 determines whether the received CA pre-response frame includes the "Channel List in Band" field 507 indicating the B-band (step S808). Furthermore, if it is determined that the "Channel List in Band" field 507 indicating the B-band is included ("Yes" in step S808), STA3 further determines whether STA2, which is the transmission source, belongs to the same BSS as STA3 with respect to the B-band (step S809).

[0126] If STA3 and STA2 are determined to belong to the same BSS ("Yes" in step S809), STA3 also sets the NAV for the PCH of the B-band (step S810). Even if the status of the PCH of the B-band changes from busy to idle, data will be transmitted between STA1 and STA2 after the channel switching of the B-band is performed. Therefore, the setting of the NAV prevents STA3 from starting data transmission unnecessarily.

[0127] In addition, when having determined that the “Channel List in Band” field 507 indicating the B band is not included (No in step S808 ), STA3 does not need to set NAV for the B band, and thus the process is terminated at this point.

[0128] Figure 9 This embodiment shows an example of operation for each communication band when a transmitting terminal transmits data using carrier aggregation using two communication bands, Band A and Band B. In this case, it is assumed that a channel of a busy communication band, whose primary channel (PCH) is switched to an idle secondary channel (SCH) (or an idle channel other than the PCH), to apply carrier aggregation.

[0129] For example, suppose a transmitting terminal performs backoff on the PCH of band A at time T901 and obtains the right to transmit. When the PCH of band B is busy at this time, the transmitting terminal can only wait to transmit until the PCH of band B becomes idle, or Figure 3 In the example shown, the use of carrier aggregation for communication is abandoned. On the other hand, in this embodiment, when the transmitting terminal detects an idle channel (SCH#1, which is in the B band) other than PCH based on the result of carrier sensing performed by the transmitting terminal on the B band, Figure 9 In the example shown, when the transmitting terminal uses the PCH of the A band to send a CA pre-request frame to the receiving terminal at time T901, the CA pre-request frame includes the "Channel Information" field 513 of the B band, in which information about SCH#1 is given.

[0130] When the receiving terminal also confirms that SCH#1 in the B-band is idle, it temporarily switches the channel used in the B-band from the PCH to SCH#1. At time T902, it returns a CA pre-response frame using the PCH in the A-band. This CA pre-response frame includes a "Channel Information" field 513, which contains information about SCH#1. The receiving terminal then waits for data reception in both the A-band and the B-band.

[0131] When the transmitting terminal confirms, based on the received CA pre-response frame, that SCH#1 in the B-band is also idle for the receiving terminal, the transmitting terminal switches the channel for use in the B-band from the PCH to SCH#1 at time T903. Then, at time T904, the transmitting terminal transmits data (data Tx) using carrier aggregation using both the A-band and B-band communication bands. In other words, even when the PCH in the B-band is busy, the transmitting terminal can also apply carrier aggregation by switching the channel in the B-band to the idle SCH#1.

[0132] The receiving terminal waits for data reception on the PCH of the A-band and the SCH#1 of the B-band. Therefore, the receiving terminal can receive data transmitted using carrier aggregation. When the receiving terminal successfully receives the data, it transmits an acknowledgment frame (ack) at time T905 using the corresponding communication bands (these are the A-band and the B-band).

[0133] In addition, when the transmitting terminal receives an acknowledgment frame (ack) from the receiving terminal using the corresponding communication frequency bands (they are A band and B band) at time T905, the transmitting terminal then resets the channel for use in the B band from SCH#1 to PCH at time T906. Therefore, for the transmitting terminal, the time period from time T903 to time T906 is a "channel switching period" in which the channel for use in the B band has been switched from PCH to SCH#1.

[0134] As mentioned above, in Figure 9 In the illustrated operation example, a CA pre-request frame and a CA pre-response frame are exchanged between a transmitting terminal and a receiving terminal to negotiate a channel to be temporarily used when performing carrier aggregation communication. This enables communication to be performed efficiently using carrier aggregation.

[0135] As in this embodiment, the transmitting terminal and the receiving terminal use the results of carrier sensing performed by the transmitting terminal and the carrier sensing performed by the receiving terminal, respectively, to detect idle channels. This allows the selection of a channel with which communication can be performed with certainty. Furthermore, surrounding terminals set NAVs based on the CA pre-notification frame or CA pre-response frame. This also prevents packet collisions when performing carrier aggregation communication.

[0136] According to the first embodiment, the CA pre-request frame and the CA pre-response frame are exchanged between the transmitting terminal and the receiving terminal to negotiate a channel to be temporarily used when performing carrier aggregation communication. This makes it possible to efficiently perform communication using carrier aggregation. In addition, both the result of carrier sensing performed by the transmitting terminal and the result of carrier sensing performed by the receiving terminal are used to detect an idle channel. This makes it possible to select a channel with which communication can be definitely performed. In addition, the surrounding terminals set the NAV based on the CA pre-request frame or the CA pre-response frame. This makes it possible to prevent packet collision when performing carrier aggregation communication.

[0137] Second Embodiment

[0138] An example in which the transmitting terminal and the receiving terminal respectively use the result of carrier sensing performed by the transmitting terminal and the result of carrier sensing performed by the receiving terminal to detect a channel for carrier aggregation has been described in the first embodiment. On the other hand, an example in which the transmitting terminal uniquely selects a channel and the receiving terminal uses the designated channel is described in the second embodiment. Compared with the first embodiment, even though the second embodiment makes it difficult to definitely select an effective channel, the second embodiment makes it possible to reduce the amount of processing performed by the receiving terminal. Therefore, the second embodiment is effective, for example, when STA1 that is the transmitting terminal is an AP and STA2 that is the receiving terminal is a non-AP STA.

[0139] Figure 10 An example of a communication sequence performed by applying the technology presented herein is shown (second embodiment). It is assumed that STA1 is a data transmitting terminal (Tx), STA2 is a data receiving terminal (Rx), and STA3 is another terminal (Other) that does not participate in data transmission. In addition, the drawing shows a flow in which STA1 performs communication using carrier aggregation by uniquely designating an idle channel (or a channel for carrier aggregation) of the B band when STA1 acquires a transmission right on the PCH of the A band. In addition, the drawing also shows a flow in which a surrounding communication terminal STA3 that neither communicates with STA1 nor communicates with STA2 sets the NAV for at least one of the A band and the B band.

[0140] First, STA1 and STA2 perform an initiation procedure to exchange capability information about their own capabilities and frequency band information to be transmitted with each other (SEQ 1001). This initiation procedure can be performed using the PCH of the A band, or using a channel other than the PCH in the A band or a communication frequency band other than the A band.

[0141] The capability information includes information indicating in which frequency band each of STA1 and STA2 can perform communication, and information on whether or not transmission and reception using carrier aggregation can be performed. It is not necessarily required to perform the initiation procedure every time carrier aggregation communication is performed. For example, first, a connection between STA1 and STA2 can be established, and then STA1 and STA2 can exchange information when there is a change in their communication state. Assume in the example of the communication sequence shown in Figure 10 STA1 and STA2 have committed to use carrier aggregation by performing the initiation procedure.

[0142] When STA1 acquires the right to transmit on the PCH of the A frequency band (SEQ 1002), STA1 prepares for CA transmission (SEQ 1003). As the preparation for CA transmission, STA1 performs determination of the SCH for use in the B frequency band. Specifically, STA1 determines whether or not the PCH of the B frequency band is idle. When the PCH of the B frequency band has been determined not to be idle, STA1 selects a channel (SCH) to be used for carrier aggregation from at least one idle channel other than the PCH in the B frequency band based on the result of carrier sensing performed by STA1, and switches the channel of the B frequency band to the selected channel in order to prepare for data communication performed using carrier aggregation. Next, STA1 transmits a CA pre-notification frame including the channel for use in the B frequency band when carrier aggregation is applied using the PCH of the A frequency band (SEQ 1004). The process of preparing for CA transmission will be described in detail later (refer to Figure 12 ). In addition, the frame configuration of the CA pre-notification frame will be described in detail later (refer to Figure 11 ).

[0143] However, when the PCH of the B frequency band is also idle, without any change, STA1 starts transmitting data using carrier aggregation by using the respective PCHs of the A frequency band and the B frequency band. This is omitted in Figure 10 . In addition, when there is no idle channel in the B frequency band (in the SCHs for which carrier sensing has been performed simultaneously with the PCH), STA1 gives up using carrier aggregation and transmits data using only the A frequency band, or waits for transmission until STA1 acquires the right to transmit also in the B frequency band to enable carrier aggregation.

[0144] When STA2 receives a CA pre-notification frame addressed to STA2, STA2 performs a process of preparing for CA reception (SEQ1005). Specifically, STA2 determines the channel (SCH) of the B band specified in the received frame as the waiting channel of the B band, and switches the channel. In addition, STA2 uses the PCH of the A band to send an ack frame for the CA pre-notification frame to STA1 (SEQ1007). In addition, when STA3 receives a CA pre-notification frame that is not addressed to STA3 on the PCH of the A band, STA3 performs NAV setting process 1 on each of the PCH of the A band and the channel of the B band included in the CA pre-notification frame (SEQ1006). The preparation for CA reception and the NAV setting process 1 will be described in detail later (refer to Figure 13 ).

[0145] When STA1 receives an acknowledgment (ack) frame for the CA pre-notification frame from STA2, STA1 transmits data using carrier aggregation using the PCH of the A-band and the idle channel (SCH) of the B-band (SEQ1008 and SEQ1009). In response, STA2 returns an acknowledgment (ack) in each of the communication bands (these are the A-band and the B-band) (SEQ1010 and SEQ1011).

[0146] After the carrier aggregation communication between STA1 and STA2 is completed, as described above, STA1 and STA2 each reset the channel for use in the B band (from the SCH for performing carrier aggregation communication) to the PCH (SEQ1012 and SEQ1013), and the process terminates.

[0147] exist Figure 10 In SEQ1007, STA2 uses the PCH of the A-band to send the ack frame. However, for example, STA2 can also use the channel (SCH) used after the channel switching of the B-band to send the ack frame. Therefore, for example, the NAV is set by the terminal belonging to another BSS (other BSS: OBSS), and the channel used after the channel switching of the B-band is always used. This makes it possible to avoid collisions in data communication using carrier aggregation.

[0148] Figure 11 An example of the format of the CA pre-notification frame is shown. The shown frame format is obtained by defining an index of the "Frame Control" field indicating a new frame type with reference to the format of the IEEE 802.11 Action frame.

[0149] "Frame Control" denoted by reference numeral 1101 is a field including information indicating the action frame type. "Duration" denoted by reference numeral 1102 is a field including time information related to the time that elapses before the subsequent carrier aggregation communication is completed. The surrounding terminals that do not perform communication read the value of this field to set NAV. "RA" denoted by reference numeral 1103 is a field including the MAC address of the transmission destination, and "TA" denoted by reference numeral 1104 is a field including the MAC address of the transmission source. Note that this frame is used only as a CA pre-notification frame and not as other frames. Therefore, there is no need for a flag given in, for example, the "Request Flag" field (refer to Figure 5 ).

[0150] The "Number of Bands" field, denoted by reference numeral 1105, specifies the number of communication bands used when carrier aggregation is applied. The "Channel List in Band" field, denoted by reference numeral 1106, contains information about channels in a communication band. The frame includes the same number of "Channel List in Band" fields as the number specified in the "Number of Bands" field.

[0151] "Channel List in Frequency Band" field 1106 includes a "Frequency Band Information" field 1111 and a "Channel Information" field 1112. "Frequency Band Information" field 1111 indicates the communication frequency band, while "Channel Information" field 1112 provides channel information related to channels designated for carrier aggregation within the communication frequency band. In this embodiment, the transmitting terminal designates one channel to be used for carrier aggregation for each communication frequency band. Therefore, the CA pre-notification frame includes only one "Channel Information" field in "Channel List in Frequency Band" field 1106.

[0152] Specifically, a transmitting terminal transmitting data using carrier aggregation provides information related to the communication band (B-band) used together with the communication band (A-band) used to transmit the CA pre-request frame when carrier aggregation is applied, to the "Band Information" field 1111 of the CA pre-notification frame. The transmitting terminal also provides information indicating the channel in the communication band (B-band) used for aggregation and specified in the "Band Information" field 1111 of the CA pre-notification frame, to the "Channel Information" field 1112 of the CA pre-notification frame.

[0153] Here, the values ​​given in the "Band Information" field 1111 and the "Channel Information" field 1112 are not particularly limited as long as these values ​​are identifiers shared by the respective communication terminals STA1, STA2, and STA3. For example, the operation class given in Annex E of IEEE 802.11-2016 can be used as "Band Information", and the channel number in the channel set given in Annex E of IEEE 802.11-2016 can be used as "Channel Information".

[0154] In addition, an "FCS" field 1107 is added at the end of the frame, in which a code for correcting errors in the entire frame is given.

[0155] Figure 12 The detailed process of the process of preparing for CA transmission is shown in the form of a flowchart. The process of preparing for CA transmission is performed by STA1 (or data transmitting terminal) in Figure 10 The communication sequence shown is executed in SEQ1003.

[0156] After STA1 obtains the transmission right on the PCH of the A-band (step S1201 ), STA1 checks whether the PCH of the B-band is idle (step S1202 ).

[0157] Here, if it is determined that the PCH of the B-band is idle ("Yes" in step S1202), STA1 starts communication using carrier aggregation using the PCHs of the A-band and B-band (step S1207). In this case, for example, STA1 can perform RTS / CTS communication before starting data communication to avoid collisions. Alternatively, both the A-band and the B-band can be widened to start data transmission.

[0158] On the other hand, if it is determined that the PCH of the B band is busy (No in step S1202), STA1 confirms the result of carrier sensing performed on channels other than the PCH in the B band (step S1203). Channels other than the PCH are, for example, the SCH on which STA1 has performed carrier sensing simultaneously with the PCH.

[0159] When STA1 has detected at least one idle channel in the B band ("Yes" in step S1204), STA1 selects a channel to use from the at least one detected channel, generates a CA pre-notification frame (refer to Figure 11 ) (which includes a "Channel List in Band" field, the "Channel List in Band" field including a "Band Information" field and a "Channel Information" field, the "Band Information" field indicating the B band, and information about the selected channel in the "Channel Information" field), and transmits the generated frame to STA2 using the PCH of the A band (step S1205). Assume that the determination in step S1204 is Figure 11 "Yes" in the communication sequence shown.

[0160] In addition, when STA1 does not detect an idle channel in the B band ("No" in step S1204), STA1 abandons the use of carrier aggregation and starts normal communication only using the PCH of the A band, or waits for data transmission using carrier aggregation until STA1 obtains the transmission right in the B band (step S1206).

[0161] Note that there are no restrictions on how STA1, for example, performs carrier sensing. Specifically, for example, according to the method for performing carrier sensing on auxiliary channels defined in IEEE 802.11, a channel where a constant power level is not detected during the PIFS interval can be detected as idle. Furthermore, when the transmitting terminal includes multiple wireless communication devices for the B-band, different channels can be set for each wireless communication device, and a channel where a preamble is not detected during the backoff period can be detected as idle.

[0162] In addition, when there are at least three frequency bands used when applying carrier aggregation, STA1 confirms the result of carrier sensing for each communication frequency band in step S1203. Finally, STA1 selects a channel to use for each communication frequency band and transmits a CA pre-request frame including only one "Channel List in Frequency Band" field in step S1205.

[0163] Figure 13 The detailed process of the process of preparing for CA reception and setting NAV is shown in the form of a flowchart. The process of preparing for CA reception and setting NAV is performed by STA2 and STA3 (or by the data receiving terminal and another terminal not participating in data transmission) in Figure 10 The communication sequence shown is executed in SEQ1005 and SEQ1006.

[0164] When a STA receives a CA pre-notification frame transmitted via the A band by another terminal (eg, STA1) intending to transmit data using carrier aggregation (step S1301), the STA determines whether the frame is addressed to the STA using the RA field (step S1302).

[0165] When it has been determined that the received CA pre-notification frame is addressed to the STA ("Yes" in step S1302), the process proceeds to the CA reception process (STA is Figure 10 In the case of STA2 in the example of the communication sequence shown in FIG. 1 ). In addition, when it has been determined that the received CA pre-notification frame is not addressed to the STA (“No” in step S1302), the process proceeds to NAV setting processing 1 (STA is Figure 10 (The example of the communication sequence shown is for the case of STA3.) The following describes these processes in the order described above.

[0166] First, the CA reception process performed by STA2 will be described. After STA2 receives a CA pre-notification frame addressed to STA2 from STA1 ("Yes" in step S1302), STA2 switches the channel of the B-band to the channel (SCH) included in the "Channel List in Band" field indicating the B-band (step S1303).

[0167] Then, STA2 returns an acknowledgment (ack) frame for the CA pre-notification frame to STA1 using the PCH of the A band (step S1304 ). Thereafter, STA2 waits for reception on the PCH of the A band and the SCH of the B band (step S1305 ).

[0168] Next, NAV setting process 1 is described. After STA3 receives a CA pre-notification frame from STA1 that is not addressed to STA3 ("No" in step S1302), STA3 reads the information given in the "Duration" field of the frame and sets the NAV for the PCH of the A band (step S1306). This allows transmission to be suppressed to avoid collisions in data communication between STA1 and STA2, which is expected to use the PCH of the A band.

[0169] Next, STA3 determines whether STA1, the transmission source, belongs to the same BSS as STA3 (step S1307). If it is determined that STA3 belongs to the same BSS as STA1 ("Yes" in step S1307), STA3 sets the NAV for the channel used for carrier aggregation in the B-band (step S1308). Even if the status of the channel used for carrier aggregation in the B-band changes from busy to idle, data will continue to be transmitted between STA1 and STA2 after performing channel switching in the B-band. Therefore, the setting of the NAV prevents STA3 from unnecessarily starting data transmission.

[0170] According to the second embodiment, a transmitting terminal sends a CA pre-notification frame to a receiving terminal to negotiate a channel to be temporarily used when performing carrier aggregation communication. This enables efficient communication using carrier aggregation. Furthermore, only the transmitting terminal uses the results of carrier sensing to search for idle channels. This reduces the processing burden imposed on the receiving terminal. Furthermore, surrounding terminals set their NAVs based on the CA pre-notification frame. This prevents packet collisions when performing carrier aggregation communication.

[0171] Third embodiment

[0172] The above describes the operation of communication using carrier aggregation. In this embodiment, a technique for performing channel switching using both a data communication channel and a control signal channel is described as an application of this operation. Note that the diagrams of the communication sequence and transmission frame used in this embodiment are similar to those of the first embodiment. Therefore, a detailed description thereof is omitted.

[0173] Figure 14 An example of a functional configuration of the communication apparatus 1400 operating as an STA (including an AP) is shown. Each component included in the communication apparatus 1400 is described below.

[0174] The communication controller 1401 controls the overall operation of the communication device 1400. In addition, the communication controller 1401 performs processing for transferring control information notified to another communication terminal to the data processor 1402. In this embodiment, the communication controller 1401 performs selection and switching of transmission / reception channels in the wireless communication sections 1405 and 1409 so as to perform communication using both the data communication channel and the control signal channel, and the communication controller 201 generates and acquires a signal including information about an idle channel.

[0175] The communication device 1400 according to this embodiment uses two communication bands, the A-band and the B-band. However, it is assumed that carrier aggregation is not applied as in the first and second embodiments described above, and that the two communication bands are assigned to different applications for independent use. Specifically, it is assumed that the B-band is a relatively narrow frequency band, such as 2.4 GHz, used to transmit control information with a small data size, while the A-band is a wide frequency band, such as 6 GHz, used to transmit a large amount of data in response to a request from an upper layer.

[0176] Therefore, the data processors that perform data processing in the MAC layer and in the PHY layer include separate data processors, which are a data processor 1406 for the A band and a data processor 1402 for the B band. The data processor 1406 includes a MAC layer data processor 1407 for the A band and a PHY layer data processor 1408 for the A band. In addition, the data processor 1402 includes a MAC layer data processor 1403 for the B band and a PHY layer data processor 1404 for the B band.

[0177] The data processor 1406 for the A band generates a transmission signal mainly based on the transmission data from the upper layer. In addition, the data processor 1406 demodulates the reception signal received from the wireless communication unit 1409 for the A band to perform a process of extracting the reception data.

[0178] Data processor 1402 for B band generates a transmission signal based on control information received from communication controller 1401 for B band. In addition, data processor 1402 demodulates a reception signal received from wireless communication section 1405 for B band to perform a process of extracting control information.

[0179] The wireless communication section 1409 performs analog conversion and RF processing on the transmission signal generated by the data processor 1406 to generate a radio signal that uses the A frequency band and is output from the antenna 1411. Furthermore, the wireless communication section 1409 performs RF processing and digital conversion on the radio signal that uses the A frequency band and is input to the antenna 1411 to generate a reception signal, and passes the generated reception signal to the data processor 1406.

[0180] The wireless communication section 1405 performs analog conversion and RF processing on the transmission signal generated by the data processor 1402 to generate a radio signal that uses the B frequency band and is output from the antenna 1410. Furthermore, the wireless communication section 1405 performs RF processing and digital conversion on the radio signal that uses the B frequency band and is input to the antenna 1410 to generate a reception signal, and passes the generated reception signal to the data processor 1402.

[0181] Note that when MIMO communication is performed using the A band and MIMO communication is performed using the B band, the wireless communication sections 1405 and 1409 each include multiple antennas, and the PHY layer data processors 1404 and 1408 each perform spatial multiplexing processing and spatial separation processing.

[0182] Figure 14 The communication device 1400 shown may also be referred to as a communication terminal, which includes wireless communication devices for multiple communication frequency bands.

[0183] Figure 15 An example is shown in which a certain transmitting terminal performs transmission using the communication band which is the A band.

[0184] For example, if a transmitting terminal performs backoff on the PCH of the A band and if another channel of the A band ( Figure 5 If the transmitting terminal (SCH1 and SCH2 in the example shown) is idle, it will need to wait for transmission when the other channel becomes busy. Advantageously, the transmitting terminal switches the channel to an idle channel for each data transmission when sending data. However, the receiving terminal only waits on the PCH of the A band. Therefore, if the transmitting terminal switches channels, data communication will not be able to be carried out correctly.

[0185] Figure 16This figure shows an example in which a transmitting terminal performs transmission using two communication frequency bands, Band A and Band B. It is assumed that CA Pre-Request frames and CA Pre-Response frames are exchanged between the transmitting terminal and the receiving terminal, and data communication is performed by flexibly switching channels, as described in the first embodiment.

[0186] For example, when a transmitting terminal performs backoff on the PCH of the B-band used for control signals and obtains the transmission right at time T1601, the transmitting terminal uses the PCH of the B-band used for control signals to send a CA pre-request frame to the receiving terminal. The CA pre-request frame includes the result of the transmitting terminal performing carrier sensing on the A-band used for data communication.

[0187] exist Figure 16 In the example shown, the PCH of band A is busy at time T1601, while SCH#1 and SCH#2 of band A are idle. Therefore, the transmitting terminal sends a CA pre-request frame including the "Channel Information" field 513 for band A, in which information about SCH#1 and SCH#2 is provided.

[0188] When the receiving terminal also confirms that SCH#1 and SCH#2 in the A-band are unavailable to the receiving terminal, it temporarily switches the channel used in the A-band from the PCH to SCH#1 and SCH#2. At time T1602, the receiving terminal uses the PCH in the B-band to return a CA pre-response frame. This CA pre-response frame includes the "Channel Information" field 513 for the A-band, which contains information related to SCH#1 and SCH#2 in the A-band. The receiving terminal then waits for data reception on SCH#1 and SCH#2 in the A-band.

[0189] When the transmitting terminal confirms, based on the received CA pre-response frame, that SCH#1 and SCH#2 in Band A are also idle for the receiving terminal, the transmitting terminal switches the channel used in Band B from the PCH to SCH#1 (or SCH#2) at time T1603. Then, at time T1604, the transmitting terminal transmits data (Data Tx) using a broadband connection that includes both channels in Band A (SCH#1 and SCH#2). In other words, even when the PCH in Band A, the communication frequency band for data transmission, is busy, the transmitting terminal can perform broadband transmission by switching the channel in Band A to the idle SCH#1 (or SCH#2).

[0190] The receiving terminal waits for data reception on SCH#1 (or SCH#2) of the A-band. Therefore, after the receiving terminal receives the preamble on SCH#1 (or SCH#2), it can receive data transmitted in the wideband using SCH#1 and SCH#2. When the receiving terminal successfully receives the data, it sends an acknowledgment frame (ack) using the channel of the A-band (which is SCH#1 (or SCH#2)) at time T1605, and then resets the channel for use in the A-band from SCH#1 (or SCH#2) to PCH.

[0191] In addition, when the transmitting terminal receives an acknowledgment frame (ack) from the receiving terminal using the channel of the A band (which is SCH#1 (or SCH#2)) at time T1605, the transmitting terminal then resets the channel for use in the A band from SCH#1 (or SCH#2) to PCH at time T1606. Therefore, for the transmitting terminal, the time period from time T1603 to time T1606 is a "channel switching period" in which the channel for use in the A band has been switched from PCH to SCH#1 (or SCH#2).

[0192] As described above, CA Pre-Notification Frames and CA Pre-Response Frames are exchanged between the transmitting and receiving terminals in the B-band, which is a communication band for control information, and the receiving terminal can switch to a waiting channel. This allows data communication to be performed correctly using any channel in the A-band, which is a communication band for data transmission.

[0193] The example using the frame exchange described in the first embodiment has been described above. However, when the transmitting terminal uniquely determines the channel to be used and transmits a CA pre-notification frame, as described in the second embodiment, the CA pre-notification frame and CA pre-response frame are exchanged between the transmitting terminal and the receiving terminal in the communication band, which is the B-band. This allows the receiving terminal to switch to a waiting channel in the communication band used for data transmission (which is the A-band). This enables correct data communication.

[0194] In addition, in this embodiment, the A band is defined as being dedicated to data, and the B band is defined as being dedicated to control signals. However, the communication band is not particularly limited to this. Both the A band and the B band can transmit data and control signals.

[0195] Industrial Applicability

[0196] The technology disclosed herein has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can modify or change the embodiments without departing from the scope of the technology disclosed herein.

[0197] The technology disclosed herein is applied, for example, to wireless LAN systems based on IEEE 802.11, switching from a primary channel to another idle channel within each communication frequency band based on the status of the primary channel. This enables highly efficient carrier aggregation using a channel access scheme using CSMA / CA. Of course, the technology disclosed herein is also applicable to wireless LAN systems other than those based on IEEE 802.11.

[0198] In other words, the technology disclosed herein has been described illustratively and should not be interpreted restrictively.In order to determine the technology disclosed herein, the claims should be considered.

[0199] Note that the technology disclosed herein can also adopt the following configurations.

[0200] (1) A communication device comprising:

[0201] a communication unit that transmits and receives radio signals using the first communication frequency band and the second communication frequency band; and

[0202] A controller controls a communication operation performed by the communication section, the controller performing control so that a signal including information on an idle channel in a second communication frequency band is transmitted using a channel in the first communication frequency band.

[0203] (2) The communication device according to (1), wherein

[0204] The controller performs control so that data is transmitted to a transmission destination of the signal using an idle channel included in the signal.

[0205] (3) The communication device according to (1) or (2), wherein

[0206] The controller performs control so that data is transmitted to a transmission destination of the signal using one of a plurality of idle channels of a second communication frequency band, the plurality of idle channels of the second communication frequency band being included in the signal.

[0207] (4) The communication device according to (3), wherein

[0208] The controller performs control so that data is transmitted using a channel designated by a response signal from a transmission destination of the signal, the designated channel being from among the plurality of idle channels included in the signal.

[0209] (5) The communication device according to (1) or (2), wherein

[0210] The controller performs control so that the signal includes information on one idle channel of the second communication frequency band, and so that data is transmitted to a transmission destination of the signal using the one idle channel of the second communication frequency band.

[0211] (6) The communication device according to any one of (1) to (5), wherein

[0212] The controller performs control so that data is transmitted to a transmission destination of the signal using carrier aggregation by utilizing respective channels of the first communication frequency band and the second communication frequency band.

[0213] (7) The communication device according to (1) or (2), wherein

[0214] The controller performs control so that data is transmitted to a transmission destination of the signal using at least one idle channel among a plurality of idle channels of a second communication frequency band included in the signal.

[0215] (8) A communication method for performing wireless communication using a first communication frequency band and a second communication frequency band, the communication method comprising:

[0216] using a channel of the first communication frequency band to transmit a signal including information about an idle channel in the second communication frequency band; and

[0217] Data is transmitted to a transmission destination of the signal using an idle channel included in the signal.

[0218] (9) A communication device comprising:

[0219] a communication unit that transmits and receives radio signals using the first communication frequency band and the second communication frequency band; and

[0220] A controller controls a communication operation performed by the communication section, the controller performing control so that a signal including information on an idle channel in a second communication frequency band is received using a channel in the first communication frequency band.

[0221] (10) The communication device according to (9), wherein

[0222] In response to receiving the signal addressed to the communication device, the controller performs control so that a reception operation is performed using a vacant channel in a second communication frequency band.

[0223] (11) The communication device according to (9) or (10), wherein

[0224] The controller performs control such that a reception operation is performed using one of a plurality of idle channels included in the signal addressed to the communication device.

[0225] (12) The communication device according to (9) or (10), wherein

[0226] The controller performs control so that a response signal including information on a channel selected from a plurality of idle channels included in the signal addressed to the communication device is returned.

[0227] (13) The communication device according to (12), wherein

[0228] The controller performs control such that a receiving operation is performed using a channel included in the response signal.

[0229] (14) The communication device according to (9) or (10), wherein

[0230] said signal addressed to said communication device comprises information relating to an idle channel, and

[0231] The controller performs control so that a reception operation is performed using the one idle channel.

[0232] (15) The communication device according to any one of (9) to (14), wherein

[0233] The controller controls reception of data transmitted using carrier aggregation by utilizing respective channels of the first communication frequency band and the second communication frequency band.

[0234] (16) The communication device according to (9) or (10), wherein

[0235] The controller performs control such that a reception operation is performed using at least one idle channel among a plurality of idle channels of a second communication frequency band included in the signal addressed to the communication device.

[0236] (16-1) The communication device according to (16), wherein

[0237] The controller controls a receiving operation of receiving data transmitted in a wideband using the plurality of idle channels of the second communication frequency band.

[0238] (17) The communication device according to (9), wherein

[0239] In response to receiving the signal addressed to the other communication device, the controller performs control so as to wait for transmission to be performed in the second communication frequency band.

[0240] (18) The communication device according to (9), wherein

[0241] In response to receiving a response signal to the signal from the other communication device, the controller performs control so as to wait for transmission to be performed in the second communication frequency band.

[0242] (19) A communication method for performing wireless communication using a first communication frequency band and a second communication frequency band, the communication method comprising:

[0243] receiving a signal including information about an idle channel in a second communication frequency band using a channel of the first communication frequency band; and

[0244] Based on the information included in the signal, transmission and reception of data performed using the second communication frequency band are controlled.

[0245] Label list

[0246] 200 communication devices

[0247] 201 Communication Controller

[0248] 202 Data Processor

[0249] 203 MAC layer data processor

[0250] 204 PHY layer data processor (for A band)

[0251] 205 PHY layer data processor (for B band)

[0252] 206 Wireless communication unit (for A band)

[0253] 207 Wireless Communication Unit (for B Band)

[0254] 208 Antenna (for A-band)

[0255] 209 Antenna (for B band)

[0256] 1400 communication device

[0257] 1401 Communication Controller

[0258] 1402 Data Processor (for B-band)

[0259] 1403 Data Processor (for B-band, MAC layer)

[0260] 1404 Data Processor (for B-band, PHY layer)

[0261] 1405 Wireless Communication Unit (for B-band)

[0262] 1406 Data Processor (for B-band)

[0263] 1407 Data Processor (for B-band, MAC layer)

[0264] 1408 Data Processor (for B-band, PHY layer)

[0265] 1409 Wireless Communication Unit (for B-band)

[0266] 1410 Antenna (for B-band)

[0267] 1411 Antenna (for A-band)

Claims

1. A communication device, comprising: a communication unit for transmitting data using a first communication frequency band and a second communication frequency band; as well as A controller that controls the communication operation performed by the communication unit, the controller performing control so that a signal including information related to one or more idle channels in the second communication frequency band is sent using a channel of the first communication frequency band, and data is sent to a sending destination of the signal by using carrier aggregation by utilizing the channel of the first communication frequency band and at least one idle channel of the second communication frequency band.

2. The communication device according to claim 1, wherein The controller performs control so that data is transmitted using a channel designated by a response signal from a transmission destination of the signal, the designated channel being from among the plurality of idle channels included in the signal.

3. A communication method for performing wireless communication using a first communication frequency band and a second communication frequency band, the communication method comprising: using a channel of the first communication frequency band to transmit a signal including information related to one or more idle channels of the second communication frequency band; and Data is transmitted to a transmission destination of the signal using carrier aggregation using a channel of the first communication frequency band and at least one idle channel of the second communication frequency band included in the signal.

4. A communication device comprising: a communication unit for transmitting data using a first communication frequency band and a second communication frequency band; as well as A controller that controls communication operations performed by the communication unit, the controller performing control so that a signal including information related to one or more idle channels of the second communication frequency band is received using a channel of the first communication frequency band, and controls reception of data sent using carrier aggregation by utilizing a channel of the first communication frequency band and at least one idle channel of the second communication frequency band. The communication device according to claim 4 , wherein In response to receiving the signal addressed to the communication device, the controller performs control so that a reception operation is performed using an idle channel of a second communication frequency band. The communication device according to claim 4 , wherein The controller performs control such that a reception operation is performed using one of a plurality of idle channels included in the signal addressed to the communication device.

7. The communication device according to claim 4, wherein The controller performs control so that a response signal including information on a channel selected from a plurality of idle channels included in the signal addressed to the communication device is returned.

8. The communication device according to claim 7, wherein The controller performs control such that a receiving operation is performed using a channel included in the response signal.

9. The communication device according to claim 4, wherein said signal addressed to said communication device comprises information relating to an idle channel, and The controller performs control so that a receiving operation is performed using the one idle channel.

10. The communication device according to claim 4, wherein The controller performs control such that a reception operation is performed using at least one idle channel among a plurality of idle channels of a second communication frequency band included in the signal addressed to the communication device.

11. The communication device according to claim 4, wherein In response to receiving the signal addressed to the other communication device, the controller performs control so as to wait for transmission to be performed in the second communication frequency band.

12. The communication device according to claim 4, wherein In response to receiving a response signal to the signal from the other communication device, the controller performs control so as to wait for transmission to be performed in the second communication frequency band.

13. A communication method for performing wireless communication using a first communication frequency band and a second communication frequency band, the communication method comprising: receiving, using a channel of the first communications frequency band, a signal including information regarding one or more idle channels of the second communications frequency band; and Based on the information included in the signal, transmission and reception of data transmitted using carrier aggregation by utilizing a channel of the first communication frequency band and at least one idle channel of the second communication frequency band are controlled.

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