The present disclosure, a communication device, a communication method and a program.
BACKGROUND
[0002]
　In recent years, advances spread of wireless LAN (Local Area Network) represented by IEEE (Institute of Electrical and Electronics Engineers) 802.11, as shown in the following Non-Patent Document 1. Further, wireless LAN products (hereinafter, referred to as a wireless communication device.) With it is increasing. When the wireless communication device is increased, collision more likely to occur when the wireless communication device performs transmission of a frame (packet), communication efficiency by the collision of the transmission is reduced.
CITATION
Non-patent literature
[0003]
非特許文献1 : IEEE　Standard　for　Information　technology　-　Telecommunications　and　information　exchange　between　systems　Local　and　metropolitan　area　networks　-　Specific　requirements　-　Part　11:　Wireless　LAN　Medium　Access　Control　(MAC)　and　Physical　Layer　(PHY)　specifications,　IEEE　Std　802.11ac,　IEEE,　2013
Summary of the Invention
Problems that the Invention is to Solve
[0004]
　The IEEE802.11 standard, as disclosed in Non-Patent Document 1, various techniques in order to avoid collision of transmission described above is employed. For example, other transmission technologies carrier sense to detect the wireless communication device before the wireless communication device starts transmission of a frame is employed.
[0005]
　However, even a non-patent has been adopted by the IEEE802.11 standard, as disclosed in Laid technology, there is a difficult situation to prevent collision transmission frame. In this disclosure, which can reduce the frequency of collisions of transmission frames occurs, a communication device, communication method, and a program are proposed.
Means for Solving the Problems
[0006]
　According to the present disclosure, based on the receiving unit and, the length information acquisition unit for acquiring the length information on the frame from the received frame, the length information the acquired another terminal receives a frame to be transmitted Te, a communication device is provided and a transmission frame determining unit for determining the length of the transmission frame.
[0007]
　Further, according to the present disclosure, based on the processor, to the, and obtaining the length information on the frame from the received frame, the length information the acquired another terminal receives a frame to be transmitted Te, and determining the length of a transmission frame, the communication method comprising is provided.
[0008]
　Further, according to the present disclosure, the processor to receive a frame other terminal transmits, from the received frame to get the length information on the frame, based on the obtained length information, transmission frame of to determine the length, the program is provided.
Effect of the invention
[0009]
　According to the present disclosure described above, the frequency of collision of transmission frames occurs is reduced.
[0010]
　Incidentally, the above effect is not necessarily limited, with the above effects, or in place of the above effects, other effects are achieved which can be grasped from either effect or herein, shown herein it may be.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
[1] Figure 1 is a diagram schematically showing a radio system according to an embodiment of the present disclosure.
FIG. 2 is station apparatus according to an embodiment of the present disclosure is a diagram showing an example of a frame format to be transmitted.
FIG. 3 is a diagram showing an example of the detection threshold of signals in the embodiments of the present disclosure.
[4] FIG. 4 is a diagram schematically showing the occurrence of a collision of a transmission frame according to an embodiment of the present disclosure.
FIG. 5 is a block diagram showing an example of the configuration of a station apparatus according to an embodiment of the present disclosure.
FIG. 6 is a diagram showing a relationship between received power and the allowable transmission power of the OBSS signal in embodiments of the present disclosure.
[7] FIG. 7 is a diagram illustrating an example collision of data transmission is avoided by the station apparatus in the embodiments of the present disclosure to adjust the length of the transmission frame.
[8] FIG. 8 is a diagram illustrating an example of processing in the embodiment of the present disclosure station apparatus.
[9] FIG. 9 is a diagram showing another example of avoiding collision of transmission frames in an embodiment of the present disclosure.
[10] FIG 10 is a diagram showing another example of avoiding collision of transmission frames in an embodiment of the present disclosure.
[11] FIG 11 is a block diagram showing an example of a schematic configuration of a smart phone which is an application example of the station apparatus in an embodiment of the present disclosure.
[12] FIG 12 is a block diagram showing an example of a schematic configuration of a car navigation device which is an application example of the station apparatus in an embodiment of the present disclosure
[13] FIG 13 is an embodiment of the present disclosure is a block diagram showing an example of a schematic configuration of a wireless access point in.
DESCRIPTION OF THE INVENTION
[0012]
　Reference will now be described in detail preferred embodiments of the present disclosure. In the specification and the drawings, components having substantially the same function and structure are a repeated explanation thereof by referring to the figures.
[0013]
　The description will be made in the following order.
　1. Overview of the wireless LAN system
　2. Configuration of the station apparatus
　3. Operation of the device
　4. Modification
　5. Application Example
　6. Supplement
　7. Conclusion
[0014]
　<1. Wireless LAN System Overview>
　an embodiment of the present disclosure relates to a wireless LAN system. First, the overview of a wireless LAN system according to an embodiment of the present disclosure.
[0015]
　(1-1. Configuration of Wireless LAN System)
　FIG. 1 is a diagram showing a configuration of a wireless LAN system according to an embodiment of the present disclosure. As shown in FIG. 1, a wireless LAN system according to an embodiment of the present disclosure, the access point device (hereinafter, referred to for convenience as "AP (Access Point)") and 200, the station device (hereinafter, for convenience to be referred to as "STA (Station)") a 100 and, the. And, the AP200 of one, and one or more of the STA100, by basic service set (hereinafter, referred to as the sake of convenience, "BSS (Basic Service Set)") 10 is constructed.
[0016]
　Incidentally, STA 100 according to the present embodiment is a communication device that communicates with AP 200, STA 100 may be any communication device. For example, STA 100 is a display having a display function, a memory having a memory function, a keyboard and a mouse having an input function, a speaker having a sound output function, or a smart phone having a function to perform advanced computation.
[0017]
　The radio LAN system according to an embodiment of the present disclosure may be installed anywhere. For example, a wireless LAN system according to this embodiment, office buildings, homes, may be installed in commercial facilities or public facilities.
[0018]
　Also, the area of ​​BSS10 according to the present embodiment overlaps the area of ​​BSS10 radio waves area other overlapping from AP 200 (hereinafter, conveniently referred to as "OBSS (Overlap Basic Service Set)") If there is a.
[0019]
　The process will be described below with reference to the example of FIG. 1, the area of ​​BSS10A is overlapped with a portion of the area of ​​BSS10B is OBSS, STA100B and STA100C is located in its overlapping area. In this case, the signal transmitted from STA100B belonging to BSS10A is observed in AP200B and STA100C belong to BSS10B. At this time, the STA100B and STA100C belonging to different BSS10 each other, based on the reception power information and the frame included in the frame transmitted from the other terminal, do some determination.
[0020]
　Figure 2 is a diagram showing an example of a frame format of the frame STA100 and AP200 sends. Of the frame format shown in Figure 2, it is described for the part related to the present embodiment. Frame format HE- preamble (hereinafter, for convenience referred to as "header") shown in Figure 2 is, L-SIG, include HE-SIG-A1 and HE-SigA2.
[0021]
　And the L-SIG, include RATE and Length. Here RATE is information indicating the data rate, Length is information indicating a frame length of the frame. These two information, the transmission time of the frame is determined. That Length can acquire the transmission time of a frame by a dividing by RATE (Length / RATE).
[0022]
　Also, the HE-SIG-A1 contains BSS Color, the HE-SIG-A2 contains TXOP Duration. BSS Color is identification information used to determine the BSS 10, STA 100 determines whether transmitted using this BSS Color, from STA 100 belonging to the received frame which BSS 10. That STA100 using the BSS Color the received frame is possible to determine whether transmitted from STA100 belonging to OBSS. In still later, conveniently a signal received from STA100 belonging to OBSS called a OBSS signal.
[0023]
　TXOP Duration included in HE-SIG-A2 is information indicating a channel use period, STA 100 also on the basis of this information, it is possible to obtain the length information of the frame.
[0024]
　3, the received power of the received OBSS signals is a diagram showing an example of the relationship between several detection threshold signal. CCA_SD is a value used to detect a preamble of a frame, CCA_ED is a value used for the received radio wave energy value. CCA_SD One example is -82dBm, CCA_ED may be -62 dBm. Incidentally, OBSS_PD is a threshold used for the received power of the OBSS signals is described below how used with OBSS_PD. Incidentally, OBSS_PD is set to a value between CCA_SD and CCA_ED as shown in FIG. Set value of OBSS_PD is, for example, -72 dBm. However the set value of OBSS_PD is not limited thereto.
[0025]
　STA100 according to IEEE802.11 standards, and performs carrier sensing before transmitting the frame, the media is either idle, is used to determine whether a busy. That STA100 determines that when performing the carrier sense, when receiving a preamble in the above received power CCA_SD, typically the media is busy. Moreover, STA 100, when receiving the radio waves from the above received power CCA_ED, does not transmit the frame.
[0026]
　(1-2. This background disclosures)
　in the above configuration of the wireless LAN system such as, smaller the influence of OBSS signal from STA100 belonging to OBSS, and STA100 may perform transmission of a frame, space re use (Spatial Reuse) has been studied.
[0027]
　Figure 4 is a diagram showing an operation example of STA100 and AP200 when spatial reuse is performed. Incidentally, AP200A shown in Figure 4, AP200B, STA100B, relations STA100C is the same as the relationship shown in FIG. In other words, AP200A and STA100B is, belong to the same BSS10A, AP200B and STA100C belong to BSS10B.
[0028]
　As shown in FIG. 4, first STA100B is described for the case of transmitting the frames. When STA100B performs transmission of a frame (F1), AP200A and STA100C receives the header of the frame (F1) which STA100B sent. STA100C which detects the signal, based on the BSS Color included in the received header, the received signal determines whether the OBSS signal. Incidentally determination OBSS signal by the STA100C may be performed by BSS Color included in the received header to determine whether the same BSS Color as BSS10B which belongs STA100C.
[0029]
　When signal STA100C was received is determined to be OBSS signal, STA100C compares the indicated in the received power and 3 of the received OBSS signal OBSS_PD. By comparison, when the received power of OBSS signal STA100C was received is determined to be equal to or less than OBSS_PD, since this OBSS signal which is assumed to have little effect on the transmission of frames STA100C, STA100C, when the media is idle judge.
[0030]
　Then STA100C starts the operation for sending the frame (F2) for AP200B of BSS10B that STA100C belongs. Transmission frame (F2) for AP200B this STA100C is performed overlaps with the transmission of the frame (F1) is OBSS signal. STA100C, as shown in FIG. 4, after waiting a backoff time to avoid collision with the transmission of a frame by the transmitting and STA100C frames from other STA100 belonging to BSS10B, the transmission of the frame (F2) Start.
[0031]
　Next, when the transmission of the frame (F1) is completed by STA100B, STA100B performs carrier sense for performing transmission of the next frame (F3). Carrier sense by the STA100B is started from the middle of the transmission of the frame (F2) by STA100C. Thus STA100B, it is difficult to receive a header of the frame STA100C transmits, frame STA100C sends does not perform determination of whether the OBSS signal. That is, the determination signal received is whether OBSS signal, to be done on the basis of the OBSS_Color included in the header, STA100B is frame STA100C sends a determination is made whether the OBSS signal it is difficult.
[0032]
　Further, STA100B, when executing the carrier sense after the transmission of a frame (F1), a higher threshold than the CCA-SD is a threshold value for detecting a preamble, from STA100C using a threshold of CCA-ED to detect the frame (F2).
[0033]
　Therefore, if the OBSS signal from STA100C arrives to STA100B the following power CCA-ED, STA100B because it does not detect a frame (F2) by STA100C, it starts transmitting a new frame (F3).
[0034]
　This STA100B transmission of the next frame by (F3), as shown in Figure 4, begins before the transmission of the frame (F2) due STA100C is completed. Therefore, in AP200B, a transmission frame (F3) from STA100B, the collision with the transmission of a frame (F2) from STA100C occur. Therefore, in the present embodiment, processing for avoiding collisions in AP200B described above is proposed.
[0035]
　　<2. Configuration> station apparatus
　above has been described with overview and context for the present disclosure of the wireless LAN system of the present disclosure. Hereinafter, with reference to FIG. 5, a description is given of a functional configuration of the station apparatus 100 according to this embodiment. Figure 5 is a block diagram showing an example of a schematic functional configuration of the station apparatus 100 according to this embodiment.
[0036]
　Station apparatus 100, as shown in FIG. 5, as the communication unit, a data processing unit 110, the control unit 120 and the wireless communication unit 130.
[0037]
　　　(Data processing unit)
　data processor 110, as shown in FIG. 5, an interface unit 111, transmission buffer 112, a transmission frame constructing section 113, a reception frame analysis section 114 and a receive buffer 115.
[0038]
　Interface unit 111 is an interface to be connected to another functional configuration provided in the station 100. Specifically, the interface unit 111, the other functional configuration, for example, receipt of data transmitted from the application is desired, or the provision of the received data to the application performs.
[0039]
　Transmission buffer 112 stores the data to be transmitted. Specifically, the transmission buffer 112 stores the data obtained by the interface unit 111.
[0040]
　Transmission frame constructing unit 113 generates a frame to be transmitted. Specifically, the transmission frame constructing unit 113 generates a frame based on the control information set by the data or control unit 120 is stored in the transmission buffer 112. For example, the transmission frame constructing unit 113 generates a frame from the data obtained from the transmission buffer 112, processing such as addition of additional and error detection code of the MAC header for medium access control (MAC) in frame generated I do.
[0041]
　Reception frame analysis section 114 analyzes the frame received. Specifically, the reception frame analysis section 114, acquires the data or control information included in the destination determination and the frame of the frame received by the wireless communication unit 130. For example, the reception frame analysis section 114, the frame to be received, the analysis of the MAC header, detection and correction of bit error, and to obtain data or the like contained in a frame which is the reception by performing reordering processing.
[0042]
　Further the received frame analyzing unit 114 determines whether the received frame is a OBSS signal described above. Specifically, the reception frame analysis section 114, based on OBSS_Color included in the received frame, a frame is received determines whether the OBSS signal. Reception frame analysis section 114, the received frame is If it is determined that the OBSS signal, among the frame format shown in Figure 2, the process of HE-SIG-A2 subsequent frames is not performed. From the above, the reception frame analysis section is an example of the signal decision unit. The reception frame analysis section 114 compares the respective threshold values ​​shown in the received power and 3 of the received OBSS signal. The reception frame analysis section 114 sends the processing control section 121 of the comparison result.
[0043]
　Reception buffer 115 stores the received data. Specifically, the receive buffer 115 stores the data acquired by the reception frame analysis section 114.
[0044]
　　　(Controller)
　controller 120, as shown in FIG. 5, comprises a processing control unit 121 and the signal control unit 122. The processing control unit 121 includes a transmission frame determining section 123, the length information obtaining unit 124.
[0045]
　Processing control unit 121 controls the operation of the data processing unit 110. Specifically, the processing control section 121 controls the generation of the communication. For example, the processing control section 121, a connection request of the communication occurs, to produce a frame according to the connection processing or authentication processing such association process or an authentication process to the data processing unit 110.
[0046]
　Further, the processing control section 121 controls the frame generated based on the analysis results of storage conditions or receive frames of data in the transmission buffer 112. For example, the processing control section 121, if the data in the transmission buffer 112 is stored, and instructs the generation of the data frame to which the data is stored in the transmission frame forming part 113. The processing control unit 121, if the received frame is checked by the receiving frame analysis unit 114, and instructs the generation of the acknowledgment frame as a response to the received frame (ACK) to a transmission frame constructing section 113.
[0047]
　Processing control section length information obtaining unit 124 in 121, based on the RATE information and Length information or channel use period included in the preamble of the received frame (TXOP Duration), the transmission time or the bit length of the received frames obtaining length information is.
[0048]
　Transmission frame determination unit 123 in the processing control unit 121, the acquired length information obtaining unit 124 as described later, determines the length of the transmission frame based on the length information of the received frame. The transmission frame determining section 123 controls the transmission timing of the transmission frame. Further transmission frame determination unit 123, based on information from the received frame analyzing unit 114 determines whether the media is idle. For example, the transmission frame determination unit 123, based on the received power of the determination result of OBSS signal received from the reception frame analysis section 114 determines whether the media is idle.
[0049]
　The signal controller 122 controls the operation of the wireless communication unit 130 based on information from the process control unit 121. Specifically, the signal control unit 122 controls the transmission and reception processing of the radio communication unit 130. For example, the signal control unit 122 to set the parameters for the transmission and reception based on the instruction of the process control unit 121 to the radio communication unit 130.
[0050]
　The signal control unit 122 controls the transmission power of the transmission frame. For example, the signal control unit, as shown in FIG. 6, may control transmission power of a transmission frame according to the received power of the OBSS signal. For example, the signal control unit 122 may transmit a frame below the threshold of power OBSS-PD. The higher the received power of OBSS signal, since the station apparatus 100 that has transmitted the OBSS signal is assumed to be close, the signal control unit 122, the transmission power predetermined transmission frame so as not to interfere with the reception of the OBSS signal lower than the transmission power of the reference. The signal control unit 122, the lower the reception power of OBSS signal, can transmit a frame without adjustment of the transmission power of the transmission frame.
[0051]
　That is, in the state of P1 shown in Figure 6, since the received power of OBSS signal is high, the signal controller 122 transmits the frame to lower the transmission power. In the state shown by P2, for the received power of OBSS signal is low, the signal controller 122 transmits the frame without adjustment of transmission power. Thus, the signal control unit 122 is an example of a transmission power control unit. The information about the received power of OBSS signal may be acquired by the reception frame analysis section 114.
[0052]
　　　(Wireless communication unit)
　Returning to the explanation of the configuration of the station apparatus 100 of FIG. 5, the radio communication unit 130, as shown in FIG. 5, a transmission processing unit 131, reception processing unit 132 and the antenna control unit 133.
[0053]
　The transmission processing unit 131 performs transmission processing of the frame. Specifically, the transmission processing unit 131, based on the frame provided from the transmission frame constructing unit 113 generates a signal to be transmitted. More specifically, the transmission processing unit 131 generates a signal according to the frame based on the parameters set by an instruction from the signal controller 122. For example, the transmission processing unit 131, the frame provided from the data processing unit 110, in accordance with coding and modulation schemes such as indicated by the control unit 120, generates a symbol stream by performing encoding, interleaving and modulation. Further, the transmission processing unit 131, a signal relating to a symbol stream obtained by the preceding processing, is converted into an analog signal, amplifies, filters, and frequency upconverts.
[0054]
　The transmission processing unit 131 may perform multiplexing processing of the frame. Specifically, the transmission processing unit 131 performs processing according to the frequency division multiplexing or space division multiplexing.
[0055]
　Reception processing unit 132 performs reception processing of the frame. Specifically, the reception processing unit 132 performs restoration of the frame based on the signals provided from the antenna control unit 133. For example, the reception processing unit 132, the signal obtained from the antenna, the inverse of the processing and during the signal transmission, for example, to obtain the symbol stream by performing frequency downconverts and digital signal conversion, and the like. Further, the reception processing unit 132, the symbol stream obtained by preceding processing, acquires the frame by performing demodulation and decoding, etc., to provide a frame to be acquired to the data processing unit 110 or the control unit 120.
[0056]
　The reception processing unit 132 may perform processing for separation of the multiplexed frame. Specifically, the reception processing section 132 is frequency-division multiplexing, or performs a process related to the separation of the frame space division multiplexing.
[0057]
　Further, the reception processing unit 132 may estimate the channel gains. Specifically, the reception processing unit 132 of the signal obtained from the antenna control unit 133, calculates the complex channel gain information from the preamble or training signal portion. Incidentally, the complex channel gain information calculated is used in processing and the frame separation process and the like according to the frame multiplexing.
[0058]
　Antenna control unit 133 transmits and receives signals via at least one antenna. Specifically, the antenna control unit 133 transmits a signal generated by the transmission processing unit 131 via the antenna, to provide a signal received through the antenna to the reception processing unit 132. The antenna control unit 133 may perform control in accordance with the space division multiplexing.
[0059]
　Although not shown in FIG. 5, the station unit 100, inputs and outputs may be provided which is connected via the interface unit 111. For example, the input unit obtains input information of the user from an input device such as a keyboard or mouse. Then, the input information and the like are stored as data in the transmission buffer via the interface unit 111. Further, data stored in the reception buffer is provided to the output unit via the interface unit 111, an output unit to output an image or music or sound such as a display or a speaker or the like on the basis of the data provided.
[0060]
　　<3. Operation> of each station device in the wireless LAN system
　above has been described the configuration of the station apparatus 100 of the present embodiment. In the following, it is described in detail the operation of the station apparatus 100 according to this embodiment. 7, to avoid the collision frame shown in Figure 4, a diagram illustrating the operation of the station apparatus 100 of the present embodiment. The height of the frame in FIG. 7 represents the transmission power of the frame. That is, the transmission power of the frame of FIG. 7 (F1) and the frame (F3) is larger than the transmission power of the frame (F2) and the frame (F4).
[0061]
　In the operation example of FIG. 4, STA100B is, because STA100C does not receive the header of the frame to be transmitted, frame STA100C sends it was difficult to make a determination of whether the OBSS signal. This STA100B begins transmission of frame collision in AP200B occurs. Therefore, in the following operation example, STA100B is, to be able to receive a header of the frame STA100C sends, STA100C adjusts the length of a transmission frame. As also shown in Figure 6, STA100B and STA100C based on the received power of the received OBSS signal, and controls the transmission power of the frame.
[0062]
　Figure 7, similarly to FIG. 4 is a diagram showing an operation example of STA100 and AP200 when spatial reuse is performed. Incidentally, AP200A shown in Figure 7, AP200B, STA100B, relations STA100C is the same as the relationship shown in FIG.
[0063]
　As shown in Figure 7, the first time STA100B performs transmission of a frame (F1), AP200A and STA100C receives the header of the frame STA100B sent. STA100C which detects the signal, based on the BSS Color included in the received header, the received signal determines whether the OBSS signal.
[0064]
　When signal STA100C is received is determined to be a OBSS signal, also received power of OBSS signal is determined to be equal to or less than OBSS_PD, STA100C determines that the media is idle. Therefore STA100C starts the operation for sending the frame (F2) for AP200B of BSS10B that STA100C belongs.
[0065]
　STA100C this time, based on the information contained in the header received from STA100B, STA100B obtains length information of a frame (F1) that transmitted. The STA100C determines reception power of the received OBSS signal. And STA100C, as indicated by the arrows in FIG. 7, to determine the frame length and transmission power of the transmission frame (F2) based on the information.
[0066]
　Frame length of a transmission frame (F2) in the example shown in Figure 7, the header of the frame (F3) transmitted by STA100C after transmission frame (F2) is to be received by the STA100B, is adjusted. More specifically, received during the switch to receiving operation STA100B from transmitting operation to complete the carrier sense for transmission of the next frame, the header of the frame (F3) transmitted by STA100C is by STA100B as is, the frame length of a transmission frame (F2) is adjusted.
[0067]
　For example, the frame length of a transmission frame (F2), as shown in FIG. 7, be adjusted so STA100B to send is complete frame transmission timing transmission is completed frame (F1) for transmitting (F2) good. This is particularly effective when it is not necessary to perform the carry sense after STA100C sent frame (F2).
[0068]
　Note STA100C by adjusting the length of the data portion of the frame format shown in FIG. 2, it may be performed to adjust the frame length. By thus the length of the frame (F2) is adjusted, STA100C can while STA100B is performing carrier sense, starts transmitting the next frame (F3). Thus, the collision of the frame in AP200B as shown in FIG. 4 is avoided.
[0069]
　In FIG. 7, since the received power of the OBSS signal received from STA100B is assumed to be larger, STA100C performs transmission of frames (F2) to lower the transmission power than the transmission power of the predetermined criteria. Thus STA100C Since transmits frame (F2) to lower the transmission power than the transmission power of the predetermined reference, the transmission of the frame (F2) by STA100C is received in AP200A frame (F1) which STA100B sends It does not affect the operation. Thus station apparatus 100 of the present embodiment, in response to the received power of the OBSS signal received, adjust the transmit power.
[0070]
　After the transmission of the frame (F2) frame length is adjusted has been completed as described above, STA100C proceeds to the operation of the transmission of the next frame (F3). STA100C is, when starting the transmission of the frame (F3), AP200B and STA100B receives the header of the frame (F3) which STA100C sent.
[0071]
　This STA100B can recognize that the transmission of the frame (F3) is performed by STA100C belonging to different BSS. And STA100B can be lower than the transmission power of the transmission power predetermined reference frame so as not to affect the reception operation (F4) of the frame (F3) by AP200B, and transmits the frame (F4).
[0072]
　By thus operating the STA100C and STA100B are controlled, transmission collisions of frames as shown in FIG. 4 is avoided. Further, since the transmission power of the transmission frame is controlled based on the received power of the OBSS signal, influence on the reception operation in AP200 is reduced. This makes it possible to improve the throughput of the entire system.
[0073]
　In the above, the operation of each station device 100 in the wireless LAN system has been described. In the following, it is described in more detail operation of each unit of the station apparatus 100 in the above-described operation.
[0074]
　Figure 8 is a flow diagram illustrating the operation of the station apparatus 100. First received frame analyzing unit 114 in S100, the received signal determines whether OBSS signal. Specifically, the reception frame analysis section 114, based on OBSS_Color included in the received frame, a frame is received determines whether the OBSS signal. Now received signal is determined not to be OBSS signal, transmission frame determining unit 123 determines that the media is busy (S102).
[0075]
　When the received signal is determined to be a OBSS signal in S100, the process proceeds to S104. Received frame analyzing unit 114 in S104, the received power of the OBSS signal is equal to or less OBSS_PD. Here, when the received power of the OBSS signal is determined to OBSS_PD larger, the station apparatus 100 determines that the media is busy (S102).
[0076]
　When the reception power of the received OBSS signal is determined to be equal to or less than OBSS_PD in S104, the process proceeds to S106. Length information obtaining unit 124 in step S106 obtains length information of a frame of the received OBSS signal.
[0077]
　Length information, as described above, are calculated based on the RATE and Length included in the header of the L-SIG. The length information may be calculated based on the TXOP Duration included in HE-SIG-A2.
[0078]
　Then the transmission frame determination unit 123 in S108, based on the length information acquired by the length information obtaining unit 124 determines the frame length of a transmission frame. The signal control unit 122 in S110, based on the received power of the determined OBSS signal at S104, determines the transmission power of the frame. Signal control unit 122 as described above, lower than the transmission power of the reference transmission power predetermined in the case of high received power of the received OBSS signal, when the received power of the OBSS signal is low perform adjustment of transmission power Absent.
[0079]
　<4. Modification>
　　(4-1. Modification 1)
　above has been described an example of the operation of the station apparatus 100 in this embodiment. In the following, it is described modification of the above-described operation example. In the following modification, transmission operation of the frame in consideration of a sequence of frames of OBSS signal STA100B is transmitted is described. For example in the first modification, as shown in FIG. 9, after the STA100B sent frame (F1), it is described an example of receiving an acknowledgment (ACK) from AP200A.
[0080]
　Modification 1 STA100B, after sending frame (F1), receives an acknowledgment (ACK) after a SIFS (Short Inter Frame Space). And STA100B, after receiving the ACK, also waits for a SIFS.
[0081]
　For STA100B to receive a header of the frame (F3) to be transmitted from STA100C, while the STA100B is executing carrier sense, STA100C must start transmission of frame (F3).
[0082]
　Thus STA100C performs frame length adjustment of the previous transmission frame (F2), also STA100B transmits a frame (F3) to complete the carrier sense. By thus sending time of the frame (F3) is controlled, STA100B may receive a header of the frame (F3) to be transmitted from STA100C. By timing of the frame transmitted is adjusted by this way STA100B, it is possible to avoid collisions of the frame at the access point 200.
[0083]
　The frame sequence according to the above-mentioned frame (F1) is an example, modifications described above in Examples of the other frame sequence is applied. For example, STA100B transmits frame (F1), receives an acknowledgment (ACK) after a SIFS, may wait further DIFS the (DCF Inter Frame Space).
[0084]
　Further, STA100B transmits frame (F1), receives an acknowledgment (ACK) after a SIFS. And STA100B waits for DIFS, may be further waiting for a predetermined back-off time. Thus, the reception of the acknowledgment to the frame sequence, may include various combinations of the frame period (IFS) and a back-off time.
[0085]
　Also, information regarding frame sequence STA100B, for example STA100B may be included in the header of the frame (F1) to be transmitted. Information about the frame sequence, for example, may be information indicating that receiving an ACK after STA100B sent frame (F1).
[0086]
　　(4-2. Modification 2)
　above, depending on the frame sequence of the frame (F1) which STA100B sends, STA100C is described an example of adjusting the timing to transmit a frame (F3). In the following, as shown in FIG. 10, STA100C is described modification 2 to receive an ACK after transmitting frame (F2).
[0087]
　Modification 2 STA100C After transmitting frame (F2), to receive an acknowledgment (ACK) after a SIFS. And STA100C After receiving the ACK, also waiting for SIFS to send a next frame (F3).
[0088]
　To receive a header of the frame (F3) to STA100B as described above is transmitted from STA100C is until STA100B completes the carrier sense, STA100C must transmit frame (F3).
[0089]
　However, when receiving an ACK after STA100C sent frame (F2), since there is a sequence for receiving an ACK, the transmission completion of the completion of the transmission of the frame (F2) frame (F1) as shown in Figure 7 When the simultaneous, STA100C is likely to be difficult to start transmission of a frame (F3) while the STA100B is performing carrier sense.
[0090]
　Thus STA100C adjusts the frame length of a transmission frame (F2) as shown in Figure 10. That STA100C, even when starting the transmission of the frame (F3) and receives an ACK after sending frame (F2), to be able to start sending a frame (F3) while the STA100B is executing carrier sense to, to shorten the frame length of the frame (F2). By thus frame length of the frame (F2) is adjusted, STA100B can receive a header of the frame (F3) to be transmitted from STA100C.
[0091]
　The frame sequence according to the frame (F2) described above is an example, modifications described above in Examples of the other frame sequence is applied. For example, STA100C, after sending frame (F2), and receives the ACK, may start the transmission of the frame (F3) waiting for DIFS. In this case STA100C may further shorten the frame length of the frame (F2) than above-described example.
[0092]
　The adjustment of the frame length STA100C described above may be made based on information about a frame sequence of frames (F2). By the frame length is adjusted by STA100C as described above, it is possible to avoid collision of frames at the access point 200.
[0093]
　　<5. Applications>
　technology according to the present disclosure is applicable to various products. For example, STA100 is, smart phone, a tablet PC (Personal Computer), notebook PC, a portable game terminal or a mobile terminal, such as a digital camera, a television receiver, a printer, a fixed terminal, such as a digital scanner or a network storage, or a car navigation system it may be implemented as an in-vehicle terminal such. Moreover, STA 100 is a smart meter, a vending machine is implemented as a remote monitoring device or POS, such as (Point Of Sale) terminal, (also called MTC (Machine Type Communication) terminal) M2M (Machine To Machine) terminal that performs communications it may be. Furthermore, STA 100 includes a wireless communication module mounted on these terminals (e.g., an integrated circuit module consists of a single die) may be used.
[0094]
　On the other hand, for example, AP 200 may be implemented as no have or router functions a router function wireless LAN access point (also referred to as a radio base station). Further, AP 200 may be implemented as a mobile wireless LAN router. Further, AP 200 includes a wireless communication module mounted on these devices (e.g., integrated circuit module consists of a single die) may be used.
[0095]
　(5-1. First application example)
　FIG. 11 is a block diagram showing an example of a schematic configuration of the smartphone 900 technology according to the present disclosure may be applied. Smartphone 900, processor 901, memory 902, storage 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, display device 910, a speaker 911, a wireless communication interface 913, an antenna switch 914, antenna 915, a bus 917, a battery 918 and the auxiliary controller 919.
[0096]
　The processor 901 may be, for example, a CPU (Central Processing Unit) or SoC (System on Chip), which controls the functions of the application layer and other layers of the smartphone 900. Memory 902 includes a RAM (Random Access Memory) and ROM (Read Only Memory), and stores programs and data executed by the processor 901. Storage 903 may include a storage medium such as a semiconductor memory or a hard disk. External connection interface 904 is an interface for connecting an external device such as a memory card or USB (Universal Serial Bus) device to a smart phone 900.
[0097]
　The camera 906 is, for example, an image pickup element such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), and generates a captured image. Sensor 907 may include, for example, the positioning sensor, a gyro sensor, the sensor group, such as a geomagnetic sensor and an acceleration sensor. The microphone 908 converts a voice inputted to the smartphone 900 to the audio signal. Input device 909, for example, a touch sensor, a keypad for detecting a touch to the screen of the display device 910, a keyboard includes a button or switch, and accepts an operation or information input from a user. Display device 910 has a screen such as a liquid crystal display (LCD) or organic light emitting diode (OLED) display, and displays the output image of the smartphone 900. Speaker 911 converts the audio signal output from the smart phone 900 to the audio.
[0098]
　Wireless communication interface 913, IEEE802.11a, 11b, support 11g, 11n, 11ac, one or more of the wireless LAN standards such as 11ad and 11ax, executes wireless communication. Wireless communication interface 913 in the infrastructure mode may communicate via other devices and the wireless LAN access point. The wireless communication interface 913, in the direct communication mode, such as the ad hoc mode or Wi-Fi Direct (TM), may communicate directly with other devices. In the Wi-Fi Direct, although one of the two terminals different from the ad hoc mode operates as an access point, the communication takes place directly between those terminals. Wireless communication interface 913 is typically the baseband processor may include such RF (Radio Frequency) circuit and a power amplifier. Wireless communication interface 913, a memory for storing a communication control program may be a one-chip module with an integrated processor and associated circuitry to execute the program. Wireless communication interface 913, in addition to wireless LAN systems, short-range wireless communication system, other types of wireless communication systems, such as the proximity wireless communication system or cellular communication system may support. Antenna switch 914, a plurality of circuits included in the wireless communication interface 913 (e.g., different circuits for wireless communication system) switches the connection destination of the antenna 915 between. Antenna 915, a single or multiple antenna elements (e.g., a plurality of antenna elements of MIMO antennas) has, are used for transmission and reception of radio signals by the wireless communication interface 913.
[0099]
　The invention is not limited to the example of FIG. 11, the smartphone 900, a plurality of antennas (e.g., antennas and proximity wireless communication method for an antenna for a wireless LAN, etc.) may be provided. In that case, the antenna switch 914 may be omitted from the configuration of the smartphone 900.
[0100]
　Bus 917, a processor 901, memory 902, storage 903, an external connection interface 904, a camera 906, a sensor 907, a microphone 908, an input device 909, display device 910, a speaker 911, connects the wireless communication interface 913 and the auxiliary controller 919 to each other . Battery 918 via a power supply line partially indicated by broken lines in the figure, supplies power to each block of the smartphone 900 shown in FIG. 11. Auxiliary Controller 919, for example, in the sleep mode, to operate the required minimum functionality of the smartphone 900.
[0101]
　Incidentally, the smartphone 900, by the processor 901 executes the access point function at the application level, may operate as a wireless access point (software AP). The wireless communication interface 913 may have a wireless access point function.
[0102]
　(5-2. Second application example)
　FIG. 12 is a block diagram showing an example of a schematic configuration of the car navigation device 920 technology according to the present disclosure may be applied. Car navigation device 920, processor 921, memory 922, GPS (Global Positioning System) module 924, sensor 925, data interface 926, content player 927, a storage medium interface 928, an input device 929, display device 930, a speaker 931, a wireless communication interface 933, antenna switch 934, an antenna 935 and a battery 938.
[0103]
　The processor 921 may be, for example, a CPU or SoC, controls the navigation functions and other functions of the car navigation device 920. Memory 922 includes RAM and ROM, for storing programs and data executed by the processor 921.
[0104]
　GPS module 924 uses the GPS signal received from the GPS satellites, measures the position of the car navigation device 920 (e.g., latitude, longitude and altitude). Sensor 925 is, for example, a gyro sensor may include sensors such as a geomagnetic sensor, and pressure sensor. Data interface 926 is connected to, for example, vehicle network 941 through a terminal (not shown), we obtain the data generated by the vehicle, such as vehicle speed data.
[0105]
　Content player 927, storage medium to be inserted into the storage medium interface 928 (e.g., CD or DVD) to reproduce the content stored in the. Input device 929 may, for example, a touch sensor for detecting a touch on the screen of the display device 930 includes a button or switch, and accepts an operation or information input from a user. Display device 930 has a screen such as an LCD or OLED display, and displays an image of content navigation function or reproducing. Speaker 931 outputs sound of content navigation function or reproducing.
[0106]
　Wireless communication interface 933, IEEE802.11a, 11b, support 11g, 11n, 11ac, one or more of the wireless LAN standards such as 11ad and 11ax, executes wireless communication. Wireless communication interface 933 in the infrastructure mode may communicate via other devices and the wireless LAN access point. The wireless communication interface 933, in the ad hoc mode or Wi-Fi Direct, etc. Direct communication mode can directly communicate with other devices. Wireless communication interface 933 is typically the baseband processor may comprise an RF circuit and a power amplifier. Wireless communication interface 933, a memory for storing a communication control program may be a one-chip module with an integrated processor and associated circuitry to execute the program. Wireless communication interface 933, in addition to wireless LAN systems, short-range wireless communication system, other types of wireless communication systems, such as the proximity wireless communication system or cellular communication system may support. Antenna switch 934 switches the connection destination of the antenna 935 between the plurality of circuits included in the wireless communication interface 933. Antenna 935 has a single or multiple antenna elements are used for transmission and reception of radio signals by the wireless communication interface 933.
[0107]
　The invention is not limited to the example of FIG. 12, the car navigation device 920 may comprise a plurality of antennas. In that case, the antenna switch 934 may be omitted from the configuration of the car navigation device 920.
[0108]
　Battery 938, via a feed line partially indicated by broken lines in the figure, supplies power to each block of the car navigation device 920 shown in FIG. 12. Further, the battery 938 accumulates electric power fed from the vehicle side.
[0109]
　The wireless communication interface 933 operates as AP200 as described above, may provide a wireless connection to the terminal user has to get on the vehicle.
[0110]
　Further, the technology according to the present disclosure includes one or more blocks of the car navigation device 920 described above, the vehicle network 941 may be implemented as an in-vehicle system (or vehicle) 940 that includes a vehicle-side module 942. Vehicle module 942, the vehicle speed, generates a vehicle data such as engine speed or failure information, and outputs the generated data to the vehicle network 941.
[0111]
　(5-3. Third Application Example)
　Fig. 13 is a block diagram showing an example of a schematic configuration of the wireless access point 950 technology according to the present disclosure may be applied. Wireless access point 950 includes a controller 951, a memory 952, an input device 954, display device 955, a network interface 957, a wireless communication interface 963, an antenna switch 964 and antenna 965.
[0112]
　The controller 951 may be, for example, a CPU or DSP (Digital Signal Processor), various functions of the wireless access point 950 IP (Internet Protocol) layer and a layer above (e.g., access restrictions, routing, encryption, firewalls and log management, etc.) to operate. Memory 952 includes RAM and ROM, a program executed by the controller 951, and various control data (e.g., terminal list, the routing table, an encryption key, such as security settings and log) for storing.
[0113]
　Input device 954 includes, for example, a button or switch, and accepts an operation from a user. Display device 955 includes an LED lamp, and displays the operation status of the wireless access point 950.
[0114]
　Network interface 957, wireless access point 950 is a wired communication interface for connecting to a wired communication network 958. Network interface 957 may include a plurality of connection terminals. Wired communication network 958 may be a LAN such as Ethernet (registered trademark), or a WAN (Wide Area Network).
[0115]
　Wireless communication interface 963, IEEE802.11a, 11b, 11g, 11n, 11ac, support one or more of the wireless LAN standards such as 11ad and 11ax, provide wireless connectivity as an access point to the vicinity of the terminal. Wireless communication interface 963 is typically the baseband processor may comprise an RF circuit and a power amplifier. Wireless communication interface 963, a memory for storing a communication control program may be a one-chip module with an integrated processor and associated circuitry to execute the program. Antenna switch 964 switches the connection destination of the antenna 965 between the plurality of circuits included in the wireless communication interface 963. Antenna 965 has a single or multiple antenna elements are used for transmission and reception of radio signals by the wireless communication interface 963.
[0116]
　　<< 6. Supplement >>
　have been described in detail preferred embodiments of the present disclosure with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such an example. It would be appreciated by those skilled in the art of the present disclosure, within the scope of the technical idea described in the claims, it is intended to cover various modifications, combinations, these for also, naturally belong to the technical scope of the present disclosure.
[0117]
　For example, the information about the frame sequence described above, STA100B and STA100C may include information indicative of the use of the block ACK. For example, when STA100B uses block ACK, STA100C the transmission of the next frame (F3) may be started immediately after the transmission of the frame (F2) shown in FIG. Also if STA100C uses block ACK, STA100C based on that information, it may adjust the frame length of the frame (F2). Specifically, STA100C, when using block ACK, as the completion of the transmission of the frame (F2) is synchronized with the completion of the transmission of a frame (F1) which STA100B sends, to adjust the frame length of the frame (F2) it may be.
[0118]
　The adjustment of the frame length of a transmission frame by the station apparatus 100 has been described above, not limited to the above-described method is an example. Adjustment of the frame length of a transmission frame by the station apparatus 100 is carried out after switching to the receiving operation STA100B from transmitting operation as shown in FIG. 7 to complete the carrier sense for transmission of the next frame, may be performed in range satisfying the header of the frame (F3) to be transmitted is received by STA100B by STA100C. In other words, adjustment of the frame length of a transmission frame by the station apparatus 100 is a range satisfying the above, so that the transmission of the frame (F2) after the completion of the transmission of a frame (F1) is completed in the example of FIG. 7 frames ( F2) frame length have be adjusted.
[0119]
　The data processing unit 110 of the station device 100, the computer program may be provided for operating as a control unit 120 and the wireless communication unit 130 described above. A storage medium such program is stored may be provided.
[0120]
　<< 7. Conclusion >>
　In this disclosure of the wireless system, as described above, the station 100 is another station apparatus 100 obtains length information of the frame from the frame to be transmitted. And based on the length information of the acquired frame, to adjust the frame length and / or transmission timing of the transmission frame. Thereby, during the period from after STA100B as shown in FIG. 7 is switched to the receiving operation from the transmission operation to complete the carrier sense for transmission of the next frame, frame (F3) transmitted by STA100C header is received by STA100B. Therefore, is avoided collision of the frame at the access point 200, the throughput of the wireless system is improved.
[0121]
　Also, the station device 100 of the present disclosure, based on the received power of the received frame, and controls the transmission power of a frame to be transmitted. This can be avoided more reliably frame collisions at the access point 200.
[0122]
　Also within the scope of the present disclosure the following configurations.
(1)
　a receiving section other terminal receives a frame to be transmitted,
　the length information acquiring unit for acquiring the length information on the frame from the received frame,
　based on the obtained length information, transmission communication device comprising: a transmission frame determination unit which determines the length of the frame.
(2)
　based on the identification information included in the received frame, the received frame is either said communication apparatus belongs networks is the signal transmitted from the other terminals belonging to different other network determining whether, and a signal determination unit, the communication apparatus according to (1).
(3)
　the signal decision unit, based on the BSS Color included in the received frame, determines whether or not sent the received frame from the other terminals belonging to said another network, said the communication apparatus according to (2).
(4)
　the length information acquiring unit, based on the information about the information and frame length on the data rate included in the received frame, obtains the length information on the frame, said from the (1) (3 communication apparatus according to any one of).
(5)
　The transmission frame determination unit, so that the transmission of the transmission frame until the transmission of frames at least the reception is completed is completed, determines the length of the transmission frame, wherein the said (1) (4) the communication device according to any one of.
(6)
　The transmission frame determining unit determines the length of the transmission frame based on the information on the channel use period included in the received frame or information regarding frame sequence of the transmission frame, wherein (1) communication apparatus according to any one of (4) from.
(7)
　said information on the frame sequence of the transmission frame, said the information about the acknowledgment received from the access point after the completion of transmission of the transmission frame, the communication apparatus according to (6).
(8)
　The transmission frame determination unit, based on the information on the frame sequence of the received frame, determines the transmission timing of the transmission frames transmitted subsequently to the transmission frame, wherein the said (1) (4 communication apparatus according to any one of).
(9)
　information regarding the frame sequence of the received frame, after completion of transmission of the transmission frame in which the other terminal sends is information about the acknowledgment the other terminal received from the access point, the (8) the communication apparatus according to.
(10)
　the transmission frame determining unit transmits at least a transmission frame in which the other terminal is sent subsequently to the transmission frame after receiving an acknowledgment from the access point, the communication apparatus according to (9) .
(11)
　the signal decision unit determines the reception power of the signal transmitted from the other terminals belonging to said another network,
　said transmission frame determination unit, the received frame belongs to the other network wherein a signal transmitted from another terminal, the other received power of a signal transmitted from said another terminal belonging to the network by following the other threshold value for a signal transmitted from the other terminals belonging to the network is the, in a case that it is determined by the signal determination unit, the media is determined to be idle, the communication device according to any one of the above (2) (10).
(12)
　the signal decision unit, the determination of other received power of the signal transmitted from the other terminals belonging to the network,
　the transmitted signal from the other terminal belonging to the determined said another network a transmission power controller for controlling transmission power of the transmission frame in response to the received power, the communication device according to any one of the above (2) (11).
(13)
　the transmission power control section reduces the transmission power of the transmission frame when the received power of the transmitted signal is greater from the other terminals belonging to the other network, the other belonging to the other network the transmission power of the transmission frame to increase when the reception power of a signal transmitted from a terminal is small, the communication device according to (12).
(14)
　by the processor,
　and the other terminal receives a frame to be transmitted,
　And that the received frame to obtain the length information on the frame,
　based on the obtained length information, the communication method comprising, determining a length of a transmission frame.
(15)
　to the processor,
　to receive the frames other terminal transmits,
　from the received frame to get the length information on the frame,
　based on the obtained length information, determines the length of the transmission frame let the program.
DESCRIPTION OF SYMBOLS
[0123]
　100 station apparatus
　110 data processing unit
　120 control unit
　130 radio communication unit
　200 the access point

WE claims

A receiving unit for other terminal receives a frame to be transmitted,
　the length information acquiring unit for acquiring the length information on the frame from the received frame,
　based on the obtained length information, the length of the transmission frame communication device and a transmission frame determination unit which determines the of.
[Requested item 2]
　Based on the identification information included in the received frame, the received frame is whether the signal transmitted from the other terminals belonging to different other networks and network to which the communication apparatus belongs determining, it includes a signal determination unit, a communication device according to claim 1.
[Requested item 3]
　The signal determination unit, based on the BSS Color included in the received frame, it determines whether or not sent the received frame from the other terminals belonging to the other network, to claim 2 the communication apparatus according.
[Requested item 4]
　The length information acquiring unit, based on the information about the information and frame length on the data rate included in the received frame, obtains the length information on the frame, the communication apparatus according to claim 1.
[Requested item 5]
　The transmission frame determination unit, so that the transmission of the transmission frame until the transmission of frames at least the reception is completed is completed, determines the length of the transmission frame, according to claim 1 Communication device.
[Requested item 6]
　The transmission frame determining unit determines the length of the transmission frame based on the information on the channel use period included in the received frame or information regarding frame sequence of the transmission frame, the communication of claim 1 apparatus.
[Requested item 7]
　It said information on the frame sequence of the transmission frame, said the information about the acknowledgment received from the access point after the completion of transmission of the transmission frame, the communication apparatus according to claim 6.
[Requested item 8]
　The transmission frame determination unit, based on the information on the frame sequence of the received frame, determines the transmission timing of the transmission frames transmitted subsequently to the transmission frame, the communication apparatus according to claim 1.
[Requested item 9]
　Information about the frame sequence of the received frame, after completion of transmission of the transmission frame in which the other terminal sends is information about the acknowledgment the other terminal receives from the access point, the communication of claim 8 apparatus.
[Requested item 10]
　The transmission frame determining unit transmits at least a transmission frame in which the other terminal is sent subsequently to the transmission frame after receiving an acknowledgment from the access point, the communication apparatus according to claim 9.
[Requested item 11]
　The signal determination unit, the determination of other received power of the signal transmitted from the other terminals belonging to the network,
　the transmission frame determination unit, the received frame is the other belonging to the other network a signal transmitted from the terminal, the received power of a signal transmitted from the other terminals belonging to the other network is below a threshold related to the transmitted signal from the other terminal belonging to the other network, If it is determined by the signal decision unit determines that the medium is idle, the communication apparatus according to claim 2.
[Requested item 12]
　The signal decision unit determines the reception power of the signal transmitted from the other terminals belonging to the other network,
　the received power of the signal transmitted from the other terminal belonging to the determined said another network depending comprising a transmission power control unit for controlling the transmission power of the transmission frame, the communication apparatus according to claim 2.
[Requested item 13]
　The transmission power control unit, the smaller the transmission power of the transmission frame when the received power of a signal transmitted from the other terminals belonging to the other network is large, from the other terminals belonging to said other network the transmission power of the transmission frame to increase when the reception power of the transmitted signal is small, the communication apparatus according to claim 12.
[Requested item 14]
　By the processor,
　and the other terminal receives a frame transmitted,
　and obtaining the length information on the frame from the received frame,
　based on the obtained length information, a length of transmission frame communication method comprising the be determined, the.
[Requested item 15]
　The processor,
　to receive the frames other terminal transmits,
　to acquire the length information on the frame from the received frame,
　based on the obtained length information, to determine the length of the transmission frame, the program .