JP2016119568A - Communication device, terminal device, communication method, communication system and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency in a receiving process on a terminal side.SOLUTION: An access point device 10 comprises: an OFDMA frame generation unit 104 for generating data frame by mapping transmission data for a terminal device by using at least one frequency channel of a plurality of frequency channels; a MAP frame generation unit 106 for generating a MAP frame that includes information indicating the frequency channel on which the transmission data generated by the OFDMA frame generation unit 104 is mapped and information indicating the destination terminal device to which the transmission data is transmitted; and a transmitting device which transmits the MAP frame generated by the MAP frame generation unit 106 by using a specific first frequency channel of a plurality of frequency channels and then transmits the data frames generated by the OFDMA frame generation unit 104 by using the frequency channel indicated by the MAP frame.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a communication device, a terminal device, a communication method, a communication system, and a program for performing wireless communication.

  The technical progress of mobile wireless data communication used when data communication is performed while a user terminal such as a mobile phone moves is remarkable, and various wireless communication schemes have been innovated and put into practical use. In recent years, there has been a communication standard that speeds up the fourth generation data communication such as LTE (Long Term Evolution) method using OFDMA (Orthogonal Frequency Division Multiple Access) technology and WiMAX (Worldwide Interoperability for Microwave Access) method. It has become mainstream.

  On the other hand, wireless LAN communication systems that have been developed with PCs (Personal Computers) as the center have been developed based on communication procedures with base stations using CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) systems. However, the IEEE 802.11 working committee, which is developing a wireless LAN communication method standard, has adopted a wireless LAN communication method based on the current CSMA / CA in order to realize more efficient data communication. On the other hand, application of OFDMA technology has just started.

  Non-Patent Document 1 and Patent Document 1 disclose processing in the case of transmitting downlink data from a base station to a terminal by OFDMA in the WiMAX (registered trademark) system. In a general OFDMA frame configuration, one frame includes a downlink subframe when data is transmitted from the base station to the terminal, and an uplink subframe when data is transmitted from the terminal to the base station. Between the two, guard times of TTG (Transmit Transition Gap) and RTG (Receive Transition Gap) are provided for switching between transmission and reception processing. Each downlink and uplink subframe is divided in two dimensions, a time axis given by an OFDM symbol and a frequency axis given by a subchannel number. One frame is periodically transmitted with a predetermined time length, and the time length of each downlink and uplink subframe is also constant. The number of subchannels is also constant. The carrier decides the frequency channel used by each base station so that it does not interfere with the WiMAX service provided by the neighboring base station (the carrier's management system may decide automatically), In addition, timing of subframe transmission from each base station is synchronized with a reference clock.

  In order for each terminal to access data for its own terminal from among the downlink data transmitted from the base station, the DL-MAP area of the downlink subframe is analyzed to find out where the data is mapped, and within the data burst The original data transmitted can be accessed by recombining the distributed data.

  On the other hand, the wireless LAN system is characterized in that an individual can purchase a base station device (Access Point: hereinafter referred to as AP) or a mobile terminal device (terminal) and install and operate it freely. For this reason, in the AP or terminal, the determination of the frequency channel of the radio wave to be transmitted and the transmission timing thereof are not managed by the communication carrier as in WiMAX. The cooperative operation with the surrounding wireless LAN system is realized by the CSMA / CA method. Specifically, a wireless LAN device that is about to start communication confirms whether or not surrounding wireless devices are emitting radio waves before starting communication, and then starts communication. If surrounding wireless devices emit radio waves, waiting for a certain period of time and if no radio waves are emitted again, radio waves are transmitted after a random time to prevent signal collision.

  As described above, the wireless LAN based on the CSMA / CA method can perform communication only when the surrounding wireless environment is not used, and it is necessary to consider a method (MU-MIMO) for spatial user multiplexing. Then, it is a specification that can send data to only one communication partner at a time. For this reason, there is a problem that the efficiency of data communication is reduced in an environment where wireless LANs are installed at high density, and it has been studied to improve the efficiency by applying the OFDMA method.

JP 2013-225851 A

Edited by Takashi Shono, “WiMAX Textbook”, Impress R & D Co., Ltd., issued July 16, 2008, p. 90

  However, when the OFDMA method is applied to a wireless LAN, it is the OFDMA method that transmits data for a plurality of terminals in one data frame from the AP. However, if the terminal does not decode all the received frames, it is addressed to its own terminal. I can't know what the data is. In addition, a feature of the wireless LAN is that the bandwidth to be transmitted for the CSMA / CA scheme described above changes dynamically, which subchannel data frame contains data addressed to the terminal itself. Not sure and receive processing can be inefficient.

  This invention is made | formed in view of this subject, The objective is to provide the communication apparatus, terminal device, communication method, communication system, and program for making a terminal perform a receiving process efficiently.

  One embodiment of the present invention relates to a communication device. This communication device is generated by a data frame generation unit that generates a data frame by mapping transmission data to a terminal device using one or more frequency channels of a plurality of frequency channels, and a data frame generation unit A MAP frame generation unit for generating a MAP frame including information indicating a frequency channel to which transmission data is mapped and information indicating a destination terminal device of the transmission data; and a specific first of the plurality of frequency channels A transmission unit that transmits a MAP frame generated by the MAP frame generation unit using one frequency channel, and then transmits a data frame generated by the data frame generation unit using the frequency channel indicated by the MAP frame. With.

  According to such an aspect, the terminal device is made to monitor the first frequency channel, and the MAP frame is received and analyzed, whereby the data addressed to the terminal device included in the data frame transmitted thereafter is efficiently accessed. It becomes possible. Therefore, in a case where the OFDMA multiplexing system is applied to a wireless system in which the wireless bandwidth to be dynamically used and the transmission timing change, such as a wireless LAN, a method for efficiently receiving data addressed to the terminal by the terminal Can provide.

  In the communication apparatus, the transmission unit transmits the MAP frame and the data frame in different subframes. In addition, the transmission unit secures the frequency channel indicated by the MAP frame in one or more second frequency channels other than the first frequency channel, which are the same subframe as the MAP frame. A signal may be transmitted. The MAP frame generation unit may include information for clearly indicating that it is a MAP frame in the MAP frame. The MAP frame generation unit may include information on a scheduled time from the transmission timing of the data frame to the reception timing of the confirmation response frame for the transmission of the data frame in the MAP frame. The MAP frame generation unit may include information for designating an acknowledgment procedure for data frame transmission in the MAP frame. The transmission unit may transmit information specifying a frequency channel to be used for transmission of the MAP frame prior to the MAP frame. According to the above aspect, it is possible to provide a technique for the terminal to efficiently receive data addressed to itself.

  Another aspect of the present invention relates to a terminal device. The terminal device generates a data frame generated by mapping transmission data for the terminal device using one or more frequency channels of a plurality of frequency channels, and indicates the frequency channel to which the transmission data is mapped Generating a MAP frame including information and information indicating a destination terminal device of the transmission data, transmitting the MAP frame using a specific first frequency channel among a plurality of frequency channels; A terminal device wirelessly connected to a communication device that transmits a data frame using a frequency channel indicated by a MAP frame, a receiving unit that receives the MAP frame and the data frame, and a MAP frame received by the receiving unit Information indicating the frequency channel to which the transmission data included in is mapped, and the transmission data MAP frame analysis unit for analyzing whether there is data addressed to the terminal device from the information indicating the destination terminal device, and the data frame received by the reception unit based on the analysis result of the MAP frame analysis unit And a data frame analysis unit for analyzing data addressed to the terminal device.

  According to such an aspect, for example, in wireless LAN communication in which transmission timing and wireless bandwidth dynamically change, the terminal device receives the MAP frame by receiving the first frequency channel, and receives and analyzes it thereafter. The data addressed to the own terminal device included in the data frame can be received efficiently.

  Further, in the terminal device, when information on a scheduled time from the transmission timing of the data frame to the reception timing of the confirmation response frame with respect to the transmission of the data frame is included in the MAP frame, the reception unit and the data frame analysis unit When the MAP frame analysis unit determines that there is no transmission data addressed to the own terminal device, the operation may be stopped until the scheduled time expires. In addition, when a frequency channel to be used for transmission of the MAP frame is designated prior to transmission of the MAP frame, the receiving unit selects a frequency channel to receive the MAP frame based on information specifying the frequency channel. You may receive by identifying.

  Another embodiment of the present invention is a program. The program is generated by a data frame generation step of generating a data frame by mapping transmission data to a terminal device using one or more frequency channels of a plurality of frequency channels, and the data frame generation step. A MAP frame generation step of generating a MAP frame including information indicating a frequency channel to which transmission data is mapped and information indicating a terminal device of a destination of the transmission data; and a specific one of the plurality of frequency channels The MAP frame generated in the MAP frame generation step is transmitted using the first frequency channel, and then the data frame generated in the data frame generation step is transmitted using the frequency channel indicated in the MAP frame. Send step and Is a program for executing the Yuta.

  Another aspect of the present invention is a communication method. The communication method is a communication method used in a communication system including a communication device and a terminal device wirelessly connected to the communication device, and the communication device uses one or more frequency channels among a plurality of frequency channels. A data frame generation step of generating a data frame by mapping transmission data to the terminal device, information indicating a frequency channel to which the transmission data generated in the data frame generation step is mapped, and a terminal of the destination of the transmission data Transmitting a MAP frame generated in the MAP frame generation step using a specific first frequency channel among a plurality of frequency channels, and generating a MAP frame including information indicating the device; After that, the frequency channel indicated in the MAP frame And transmitting the data frame generated in the data frame generating step using the network, and the terminal device receives the MAP frame and the data frame, and receives the MAP frame received in the receiving step. A MAP frame analysis step for analyzing whether there is data addressed to the own terminal device from information indicating the frequency channel to which the included transmission data is mapped and information indicating the destination terminal device of the transmission data; A data frame analysis step for analyzing data to be received from the data frame received in the reception step based on the analysis result of the frame analysis step.

  Another aspect of the present invention is a communication system. The communication system includes a communication device and a terminal device wirelessly connected to the communication device, and the communication device transmits to the terminal device using one or more frequency channels among a plurality of frequency channels. A data frame generation unit that generates a data frame by mapping data, information indicating a frequency channel to which transmission data generated by the data frame generation unit is mapped, information indicating a terminal device that is a destination of the transmission data, and A MAP frame generation unit that generates a MAP frame including the MAP frame, and a MAP frame generated by the MAP frame generation unit using a specific first frequency channel among a plurality of frequency channels, and then the MAP frame Generated by the data frame generator using the frequency channel indicated by Information indicating a frequency channel to which transmission data included in the MAP frame received by the receiving unit is mapped, and a receiving unit that receives the MAP frame and the data frame. And a receiving unit based on the analysis result of the MAP frame analyzing unit and the MAP frame analyzing unit for analyzing whether there is data addressed to the terminal device from the information indicating the destination terminal device of the transmission data. A data frame analysis unit for analyzing the data addressed to the terminal device from the received data frame.

  It should be noted that any combination of the above-described constituent elements and a representation of the present invention converted between a method, an apparatus, a system, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, it is possible to provide a communication device, a terminal device, a communication method, a communication system, and a program that can efficiently receive data addressed to the terminal on the terminal side.

It is a figure which shows the structural example of the radio | wireless frame of a general wireless LAN system. It is a figure which shows the mode of the carrier sense by a general CSMA / CA system. It is a figure which shows the structural example of the radio | wireless communications system concerning one Embodiment of this invention. It is a figure which shows the structural example of the access point of FIG. It is a figure which shows the structural example of the terminal device of FIG. 4 is a flowchart showing an operation example of the access point of FIG. 3. It is a figure which shows the structural example of the OFDMA frame by the combination of a subchannel. It is a figure which shows the structural example of the MAP frame of 1st Embodiment. It is a figure which shows an example of the transmission procedure of the MAP frame in 1st Embodiment. It is a figure which shows an example of the reception procedure of the confirmation response signal in 1st Embodiment. It is a figure which shows an example of the transmission procedure of the MAP frame in 2nd Embodiment. It is a figure which shows an example of the transmission procedure of the beacon frame in 2nd Embodiment. It is a figure which shows the structural example of the MAP frame of 3rd Embodiment. It is a figure which shows an example of the transmission procedure of the MAP frame in 3rd Embodiment.

(Outline of the present invention)
Before describing the embodiments of the present invention, an outline of the present invention will be described first. The present invention relates to a communication apparatus that operates as an access point (AP) for wireless LAN communication, for example. A communication apparatus according to the present invention includes, for example, a data frame generation unit that generates a data frame by mapping transmission data to a terminal apparatus using one or more frequency channels of a plurality of frequency channels, and a data frame generation A MAP frame generation unit for generating a MAP frame including information indicating a frequency channel to which transmission data generated by the unit is mapped, and information indicating a destination terminal device of the transmission data, and a plurality of frequency channels The MAP frame generated by the MAP frame generation unit is transmitted using the specific first frequency channel, and then the data frame generated by the data frame generation unit using the frequency channel indicated by the MAP frame. And a transmission unit for transmitting.

  FIG. 1 is a diagram illustrating a configuration example of a wireless frame of a general wireless LAN system. The radio frame (PHY frame) includes a preamble, SIGNAL, and data. The preamble added to the head is a fixed waveform signal necessary for signal reception synchronization processing, and the terminal performs synchronization processing, detection processing, and the like necessary for signal decoding by the preamble.

  Also, the terminal can analyze the OFDM symbol called SIGNAL following the preamble and know the transmission rate and data length of the subsequent data. Based on the known transmission rate and data length, the terminal decodes the data and extracts the MAC frame. There is a destination address field in the MAC header, and the terminal can finally know that data destined for the terminal exists by acquiring the destination address.

  In the OFDMA method, it is possible to transmit data addressed to a plurality of terminals at the timing of transmitting one data frame from the AP. However, if the terminal does not decode all received frames, the terminal knows whether the data is addressed to itself. Can't get. In addition, a feature of the wireless LAN is that the bandwidth of the wireless channel to be transmitted for the CSMA / CA system changes dynamically, but it is not clear which sub-channel data frame contains the data addressed to the terminal itself. There is no problem.

  FIG. 2 is a diagram showing a state of carrier sense by a general CSMA / CA method. In FIG. 2A, since none of the subchannels of CH-1 to CH4 is unused, data frames can be transmitted in a wide band of CH-1 to CH-4. On the other hand, when it is detected by carrier sense that CH-3 and 4 are in use as shown in FIG. 2B, data frames are only used in the narrower CH-1 and CH-2 bands than in FIG. Cannot be sent. Thus, since the band used for transmission changes when the surrounding radio wave environment changes dynamically, it is difficult to provide a map field indicating the location of user data at the beginning of the data frame, such as WiMAX. is there.

  In the present invention, for example, in wireless LAN communication in which transmission timing and usable wireless bandwidth dynamically change, a terminal device monitors a specific first frequency channel to which a MAP frame is mapped, and receives a MAP frame. By performing the analysis, it is possible to efficiently receive the data addressed to the terminal device included in the data frame transmitted thereafter. As a result, it is possible to solve the problem that the terminal can only know whether there is data addressed to the terminal after receiving and analyzing all the data. It should be readily understood by those skilled in the art that the present invention can be applied not only to the OFDMA system but also to a frequency division multiplexed system.

(First embodiment)
[Configuration example of wireless communication system]
FIG. 3 is a diagram illustrating a configuration example of the wireless communication system 100 according to the embodiment of the present invention. The wireless communication system 100 includes an access point 10 and a plurality of terminal devices 20-1 to 20-4 used by users 1 to 4, respectively. The terminal devices 20-1 to 20-4 located in the wireless LAN area of the access point 10 can be connected via the access point 10 to a higher level network or other communication devices located in the wireless LAN area. it can. In this specification, when it is not necessary to identify each of the terminal devices 20-1 to 20-4, the terminal devices 20-1 to 20-4 are collectively referred to as the terminal device 20. Further, the number of terminal devices 20 can be arbitrarily changed.

[Example of access point configuration]
FIG. 4 is a diagram illustrating a configuration example of the access point 10 (hereinafter also referred to as AP 10) in FIG. The AP 10 includes at least a transmission data buffer unit 102, an OFDMA frame generation unit 104, a MAP frame generation unit 106, a radio transmission / reception unit 108, and a control unit 110 that controls each unit in the access point. It is obvious that there are other necessary components for the access point for wireless LAN communication, but the description is omitted here.

  The transmission data buffer unit 102 temporarily stores data to be transmitted, and notifies the control unit 110 of data information including the data destination and data size. In addition, the transmission data buffer unit 102 passes the temporarily stored data to be transmitted to the OFDMA frame generation unit 104.

  The OFDMA frame generation unit 104 maps the data passed from the transmission data buffer unit 102 using one or more subchannels of the plurality of subchannels in accordance with the mapping instruction from the control unit 110, thereby generating an OFDMA frame. Is generated. The generated OFDMA frame is supplied to the wireless transmission / reception unit 108 in accordance with a transmission instruction from the control unit 110.

  Based on the mapping pattern information notified from the control unit 110, the MAP frame generation unit 106 includes information indicating the subchannel to which the transmission data generated by the OFDMA frame generation unit 104 is mapped, and the destination of the transmission data. A MAP frame including information indicating the terminal device is generated. In the MAP frame, information such as a type identifier for clearly indicating that the frame is a MAP frame is included.

  In addition, the MAP frame generation unit 106 specifies information on the scheduled time from the transmission timing of the data frame to the reception timing of the confirmation response frame for the transmission of the data frame and the confirmation response procedure for the transmission of the OFDMA frame in the MAP frame. Information may be included. For example, when data addressed to a plurality of terminals is mapped to one OFDMA frame, in order to receive an acknowledgment signal from the plurality of terminals, a signal requesting the acknowledgment signal is transmitted on the subchannel in order. A procedure for receiving an acknowledgment signal can be used. The generated MAP frame is supplied to the wireless transmission / reception unit 108 in accordance with a transmission instruction from the control unit 110.

  The radio transmission / reception unit 108 performs carrier sense in accordance with a carrier sense instruction from the control unit 110, and responds to the control unit 110 with information on unused and usable subchannels in the usable band. Further, under the control of the control unit 110, the radio transmission / reception unit 108 transmits the MAP frame generated by the MAP frame generation unit 106 using a specific subchannel among the plurality of subchannels via an antenna.

  After a certain time of the transmission, the OFDMA frame generated by the OFDMA frame generation unit 104 is transmitted through the antenna using the subchannel indicated by the MAP frame. The radio transmission / reception unit 108, in accordance with an instruction from the control unit 110, uses another frame (for example, for securing the subchannel indicated by the MAP frame in one or more subchannels other than the specific subchannel) CTS2self) or the exact same MAP frame may be transmitted. Further, the wireless transmission / reception unit 108 may include information specifying a frequency channel to be used for transmission of the MAP frame in a beacon frame or the like and transmit the information prior to the MAP frame.

[Configuration example of terminal device]
FIG. 5 is a diagram illustrating a configuration example of the terminal device 20 of FIG. The terminal device 20 includes at least a wireless transmission / reception unit 202, an OFDMA frame analysis unit 204, a MAP frame analysis unit 206, a reception data buffer unit 208, and a control unit 210 that controls each unit in the terminal device. . It is obvious that there are other necessary components for the terminal device for wireless LAN communication, but the description is omitted here.

  In accordance with the MAP frame reception instruction from the control unit 210, the radio transmission / reception unit 202 receives a MAP frame via an antenna using a specific subchannel of the plurality of subchannels. Thereafter, according to the OFDMA frame reception instruction from the control unit 210, the OFDMA frame is received via the antenna using the subchannel indicated by the received MAP frame. Radio transceiver 202 transmits an acknowledgment signal for the transmission of the OFDMA frame from access point 10 in accordance with an acknowledgment signal transmission instruction from controller 210.

  The MAP frame analysis unit 206 determines, from the information indicating the frequency channel to which the transmission data included in the MAP frame received by the wireless transmission / reception unit 202 is mapped, and the information indicating the destination terminal device of the transmission data, It analyzes whether or not there is addressed data, and notifies the control unit 210 of the MAP frame analysis result. When there is data addressed to the terminal device based on the MAP frame analysis result, the control unit 210 transmits an OFDMA frame reception instruction to the wireless transmission / reception unit 202. The OFDMA frame reception instruction includes, for example, a bandwidth and a subchannel number as information indicating a frequency channel to which data addressed to the terminal is mapped.

  The OFDMA frame analysis unit 204 analyzes the OFDMA frame received by the wireless transmission / reception unit 202, acquires data addressed to the own terminal device, and outputs the data to the reception data buffer unit 208. Further, the OFDMA frame analysis unit 204 notifies the control unit 210 of an OFDMA frame analysis result indicating whether or not the data addressed to the terminal apparatus has been correctly received.

  Based on the OFDMA frame analysis result, the control unit 210 instructs the wireless transmission / reception unit 202 to transmit an acknowledgment signal when the data addressed to the terminal device is correctly received. When the MAP frame includes information for designating an acknowledgment procedure for the transmission of the OFDMA frame, the control unit 210 transmits the confirmation response signal to the radio transmission / reception unit 202 according to the information. Instruct. Alternatively, when there are a plurality of destination terminals in the MAP frame, the control unit 210 may voluntarily switch the response procedure of the confirmation response signal. The response procedure will be described later.

  The reception data buffer unit 208 stores the data addressed to the own terminal device acquired by the OFDMA frame analysis unit 204 and supplies the data to the control unit 210 as necessary.

  In the case where the MAP frame includes information on the scheduled time from the transmission timing of the data frame to the reception timing of the acknowledgment frame for the transmission of the data frame, the MAP frame analysis unit 206 transmits the transmission data addressed to the terminal device itself. When it is determined that there is no data, the wireless transmission / reception unit 202 and / or the OFDMA frame analysis unit 204 can perform a power saving operation such as stopping the operation until the scheduled time expires. In addition, when a frequency channel to be used for transmission of the MAP frame is specified by a beacon frame or the like prior to transmission of the MAP frame, the radio transmission / reception unit 202 transmits the MAP frame based on information specifying the frequency channel. It can be received by identifying the frequency channel to be received.

[Operation example of access point]
FIG. 6 is a flowchart showing an operation example of the access point 10 of FIG.
The transmission data buffer unit 102 receives data to be transmitted from the upper network (S1a), and notifies the control unit 110 of the destination and the data size from the analysis result of each data (S1b).

  Since there is data to be transmitted, the control unit 110 instructs the wireless transmission / reception unit 108 to perform carrier sense. The wireless transmission / reception unit 108 performs carrier sense, and responds to the control unit 110 with information on subchannels that are unused and available in the usable band (S1c). At this time, it is assumed that the first CH (referred to as a primary channel in the wireless LAN standard) used for management, control, etc. of terminals connected to the access point via a wireless LAN can be used. To do. The radio transmission / reception unit 108 continues carrier sense and monitors whether the subchannel identified as usable is unused.

  When there is a usable subchannel and the first CH is usable, the control unit 110 sets a random waiting time and starts a countdown (S1d). Then, control section 110 instructs OFDMA frame generation section 104 on a mapping pattern of data addressed to a plurality of terminals based on the available subchannel arrangement information. The OFDMA frame generation unit 104 receives mapping pattern information indicating which sub-channel data is mapped to which sub-channel from the control unit 110, and based on the data for the terminal copied from the transmission data buffer unit 102 An OFDMA frame is generated (S1e).

  Here, it is assumed that data for a certain terminal is not mapped across a plurality of OFDMA frames. For example, when all of the 80 MHz width composed of four 20 MHz wide subchannels can be used, one subchannel is 20 MHz, two subchannels are bundled to 40 MHz, and four subchannels are bundled to be used as an 80 MHz bandwidth. be able to. The individual subchannels to be bundled may be adjacent to each other on the frequency axis or may be separated from each other.

  FIG. 7 includes FIGS. 7A and 7B and is a diagram illustrating a configuration example of an OFDMA frame based on a combination of subchannels. FIG. 7A shows data for user 1 in subchannel 1, data for user 2 in subchannel 2, data for user 3 in subchannel 3, and user 4 in subchannel 4. An example of assigning the data is shown. FIG. 7B shows an example in which data for user 1 is assigned to subchannel 1, data for user 2 is assigned to subchannel 2, and data for user 3 is assigned to subchannels 3 and 4.

  FIG. 7C shows an example in which data for user 1 is assigned to subchannels 1 and 2 and data for user 2 is assigned to subchannels 3 and 4. As shown in FIG. 7A, FIG. 7B, and FIG. 7C, an OFDMA frame can be configured by placing user data on subchannels in various arrangements. Note that data addressed to a plurality of users may be assigned to one subchannel. A specific method for mapping terminal-oriented data to each OFDMA frame is out of the scope of the present invention.

  In parallel, the control unit 110 transmits mapping pattern information indicating to which sub-channel the data addressed to which terminal is mapped to the MAP frame generation unit 106. The MAP frame generation unit 106 generates a MAP frame based on the mapping pattern information received from the control unit 110.

  FIG. 8 is a diagram illustrating a configuration example of a MAP frame according to the first embodiment. The configuration example of the MAP frame shown here is a payload of a PHY frame that is realized as a MAC frame of a wireless LAN system and defined by the wireless LAN. The MAP frame includes a frame control field, a duration field, a destination address field, a base station address field, a transmission source address field, a sequence control field, a payload, and an FCS.

  In the frame control field, “MAP frame” or an identification number corresponding to “MAP frame” is designated as a type identifier. In addition, in order to identify whether or not an unspecified number of terminals are present in a data frame in which data addressed to the own terminal is present, the destination address field indicates address information indicating “broadcast” or an unspecified number of terminals. Information may be specified.

  In the base station address and the source address field, the address of the AP 10 is specified. The payload field stores data indicating terminal mapping. FCS is a frame check sequence, and is used to check for errors in received MAC frames. Note that the type identifier indicating the MAP frame may be provided at the beginning of the payload.

  The payload field includes combination number information indicating the number of OFDMA subchannel information and a plurality of OFDMA subchannel information 1 to N (N: natural number). Each OFDMA subchannel information corresponds to the used bandwidth of the OFDMA frame, information on the subchannel to be used, the number of destination terminals of data multiplexed on the subchannel, and the number of destination terminals of the data. The ID information of a plurality of terminals is stored in a manner associated with each other as a set of parameter groups.

  The bandwidth and subchannel number used by the subchannel may represent a relative position and bandwidth with respect to the first CH with reference to the first CH. The terminal ID information may be a MAC address, or an ID (for example, an Association ID) given at the time of initial connection with the AP may be used. Further, when the ID is determined based on the set bit position, the number of destination terminals can be eliminated.

  For example, when data for a plurality of terminals is mapped to one subchannel, a value of 2 or more is set to the number of destination terminals of the OFDMA subchannel information. As for whether user data is mapped to the terminal and notified to the terminal, each terminal extracts only the data addressed to itself using the number of destinations included in the OFDMA subchannel information and the terminal ID information (pattern). ) May be specified separately.

  In addition, when data addressed to a plurality of terminals is mapped to one subchannel, in order to receive an acknowledgment signal from the plurality of terminals, a signal requesting the acknowledgment signal is transmitted on the subchannel in order. A procedure for receiving the acknowledgment signal is required. An identifier designating this confirmation response procedure may be included in the OFDMA subchannel information of the MAP frame.

  Returning to the description of FIG. Here, when the countdown of the random waiting time expires while the subchannel that the wireless transmission / reception unit 108 continues to monitor is usable (S1f: Yes), the control unit 110 transmits the MAP frame to the MAP frame generation unit. Instruct.

  The MAP frame generation unit 106 delivers a MAP frame that has been created in accordance with an instruction from the control unit 110 to the wireless transmission / reception unit 108. The wireless transmission / reception unit 108 converts the MAP frame into a wireless frame in accordance with wireless LAN regulations, and transmits a wireless space via an antenna. (S1g). At this time, in the first embodiment, it is assumed that the MAP frame is transmitted using only the first CH.

  The control unit 110 instructs the OFDMA frame generation unit 104 to transmit the OFDMA frame after a certain time (SIFS) has elapsed after the transmission of the MAP frame. The OFDMA frame generation unit 104 delivers the created OFDMA frame to the wireless transmission / reception unit 108 in accordance with an instruction from the control unit 110, and the wireless transmission / reception unit 108 converts the OFDMA frame into a wireless frame according to the wireless LAN regulations, via the antenna. Transmit to the wireless space (S1h).

  FIG. 9 is a diagram illustrating an example of a procedure for transmitting a MAP frame in the first embodiment. FIG. 9A shows the transmission procedure with the horizontal axis as the time axis and the vertical axis as the frequency axis. The MAP frame is transmitted only on the first CH, and each terminal can receive the MAP frame if only the first CH is monitored and received. Further, data communication with respect to the four terminals indicated by user1 to user4 is possible in a wider band. Here, each terminal can know in which subchannel the data addressed to itself is transmitted by referring to the received MAP frame. As a result, it is possible to solve the problem that it is not possible to know whether there is data destined for the terminal itself after receiving and analyzing all the data. Since subchannels for receiving data are limited and it can be identified that there is no data for the terminal by the MAP frame, the receiving operation can be made efficient.

  In FIG. 9A, subchannels other than the first CH are unused at the transmission timing of the MAP frame, and other wireless devices may start transmission during this time. When another wireless device starts transmission, there is a concern that OFDMA frames to be transmitted thereafter collide. In order to avoid this, some other frame may be transmitted simultaneously with the MAP frame. For example, as shown in FIG. 9B, it is also desirable to secure a band by transmitting a CTS frame defined by the wireless LAN to the AP 10 itself (CTS2self). The MAP frame may be copied and transmitted at the same timing over all subchannels.

  When the OFDMA frame reaches a plurality of destination terminals and decoding is successful, the wireless transmission / reception unit 108 receives an acknowledgment signal for the transmission of the OFDMA. The wireless transmission / reception unit 108 transmits the information of the acknowledgment signal received from the terminal that is the destination of each OFDMA frame to the control unit 110. The procedure for transmitting an acknowledgment signal on each terminal side is out of the scope of the present invention.

  FIG. 10 is a diagram illustrating an example of an acknowledgment signal reception procedure in the first embodiment, and illustrates an acknowledgment signal reception procedure for transmission of an OFDMA frame. When data addressed to a plurality of terminals is mapped to one subchannel, it is necessary to receive acknowledgment signals from the plurality of terminals. When receiving acknowledgment signals from a plurality of terminals, according to identifiers specifying the acknowledgment procedure included in the OFDMA subchannel information of the MAP frame, the acknowledgment signals are transmitted as shown in the third CH and the fourth CH in FIG. It is good also as transmitting the signal (Ack Request) to request | require in the said subchannel, and receiving an acknowledgment signal in order.

  In other words, the response procedure refers to the order in which a plurality of terminal devices transmit response signals to one AP. In addition, when it is detected that there are a plurality of destination terminals in the OFDMA subchannel information, the terminal voluntarily transmits an answer signal in anticipation of an identifier that specifies the response procedure of the acknowledgment signal. Instead of waiting for the instructed identifier, the control may be switched to control that transmits a response signal according to the identifier.

  Or, a plurality of terminal devices do not transmit response signals to one AP in order, but further subdivide subchannels on the frequency axis, or code-multiplex using different spreading codes. If the terminal devices can simultaneously transmit response signals, this may be designated.

  Returning to the description of FIG. Here, when the control unit 110 determines that the data to each terminal transmitted by the OFDMA frame is normally received by receiving the acknowledgment signal (S1i: Yes), the control unit 110 remains in the transmission data buffer unit 102. The data transmitted to the terminal is deleted (S1j). If reception confirmation cannot be performed within a certain reception waiting time of the confirmation response signal (S1i: No), the process proceeds to S1b, and transmission is performed again with another OFDMA frame mapping at the next transmission opportunity.

  Further, when the control unit 110 detects use by another wireless device in a usable subchannel that is continuously monitored by the wireless transmission / reception unit during the random standby time countdown (S1f: No), the MAP The transmission of the frame and the OFDMA frame is stopped, the process proceeds to S1b, and a MAP frame and an OFDMA frame are newly generated based on the combination of subchannels that can be used at the next opportunity, and the transmission is performed again.

  Furthermore, it is also desirable to set the time from the transmission timing of the OFDMA frame to the completion of reception of the acknowledgment signal for the transmission of the OFDMA frame in the duration field of the MAP frame. As a result, a terminal that has received a MAP frame but has identified that there is no data addressed to itself can operate in the power saving mode because there is no data for itself for the time set in the duration field of the MAP frame. become.

  As described above, according to the first embodiment, the terminal device receives the MAP frame in the first CH, thereby knowing that the data addressed to the terminal device is transmitted at the next timing, and in the OFDMA frame. By knowing the arrangement of user data, it is possible to efficiently receive and decode data only on the designated subchannel without receiving and decoding data over all frequency bands.

  For example, if it is assumed that 80 MHz is available and data for each terminal is always transmitted only in the 20 MHz width, the terminal device should always receive in the 20 MHz width, so that the power consumption required for reception is 4 It can be reduced by a factor. In addition, by setting the time required for transmission in the duration field of the MAP frame, when the terminal device identifies that the data for the terminal itself is not included in the OFDMA frame, it is possible to realize further power saving operation. . It is clear that this is more efficient than the conventional method in which there are sub-channels that cannot be used or sub-channels that need not be received but must be received over the entire band.

(Second Embodiment)
A second embodiment will be described with reference to FIGS. 11 and 12. FIG. 11 is a diagram illustrating an example of a MAP frame transmission procedure according to the second embodiment. FIG. 12 is a diagram illustrating an example of a procedure for transmitting a beacon frame in the second embodiment.

  In the second embodiment, in the transmission of the S1g MAP frame in FIG. 6 described above, not only the first CH but also all the available subchannels 1st to 4th CHs are copied and transmitted. However, the bandwidth of the MAP frame is the same as the bandwidth of the first CH. The transmission procedure is as shown in FIG. 11A, and all MAP frames indicate mapping of data addressed to terminals of all OFDMA frames. In the first embodiment, when the first CH is in use at the timing of carrier sense, the transmission has to be stopped over the entire band. According to the second embodiment, FIG. As described above, the OFDMA frame can be transmitted using the subchannels of the second CH to the fourth CH that are not in use, and the transmission opportunities can be increased.

  In addition, in the terminal in 1st Embodiment, only the MAP frame by 1st CH was received and the position of the OFDMA frame for self terminals was able to be known, but in 2nd Embodiment, it extended over several subchannels. The inefficiency of having to receive MAP frames arises. The following implementation may be provided as a means for alleviating this. In a wireless LAN, an AP periodically transmits a beacon frame to control a terminal under its control. The transmission interval is usually about 100 milliseconds. The AP measures the rate of time during which the first CH was occupied by another wireless device for 100 milliseconds before transmitting the beacon frame. Alternatively, the usage rate by other wireless devices of the first CH may be estimated using the probability that the MAP frame can be transmitted on the first CH.

  For example, as shown in FIG. 12, the band for receiving the MAP frame may be changed. In FIG. 12, the horizontal axis is a time axis, and shows a mode in which five beacon frames B1 to B5 are transmitted in order. In addition, it shows how long the first CH is used before and after each beacon frame.

  Here, when the usage rate of the first CH before each beacon frame exceeds a predetermined threshold (for example, beacon frames B2 and B3), all subchannels are used as in the second embodiment. Information specifying that the beacon is to be included in beacon frames B2 and B3. On the other hand, when the usage rate of the first CH is below a predetermined threshold (for example, beacon frames B1, B4, B5), information specifying that only the first CH is used as in the first embodiment. Are transmitted in beacon frames B1, B4, and B5. This information may use, for example, a transmission channel bit that is one of the parameters in the field indicating the OFDMA-related capability information in the beacon frame (for example, transmission channel bit = 0: only the first CH is used. MAP frame is transmitted, 1: MAP frame is transmitted using all subchannels). Each terminal is defined to receive beacon frames periodically. By identifying the information specified in each beacon frame, the band for receiving the MAP frame transmitted following the beacon frame is changed. can do.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 13 and 14. FIG. 13 is a diagram illustrating a configuration example of a MAP frame according to the third embodiment. FIG. 14 is a diagram illustrating an example of a procedure for transmitting a MAP frame in the third embodiment.

  In the third embodiment, there is one terminal indicated in the MAP frame transmitted in each subchannel, and the destination of the MAP frame itself is not broadcast but unicast to the terminal indicated in the MAP frame. For example, when mapping the data addressed to the terminal device 20-2 to the subchannel of the second CH, the MAP frame generation unit 106 generates a MAP frame as shown in FIG.

  FIG. 13 is a modification of FIG. 8 and is different in that the transmission target is one terminal. Therefore, the payload field can be omitted. Specifically, in FIG. 13, “address of terminal device 20-2” is designated in the destination address field.

  The MAP frame transmission procedure in the third embodiment is as shown in FIG. In FIG. 14 (a), the AP 10 unicasts the MAP frame to the terminal devices 20-1 to 204 using the corresponding first CH to fourth CH after passing through a random waiting time after carrier sense. Send. Here, the AP 10 expects a response signal from each terminal device to be returned.

  However, for example, as illustrated in FIG. 14B, when the second channel and the third CH subchannel are already in use on the terminal device 20-2 side, the MAP frame transmitted to the terminal device 20-2 is transmitted. The 2CH sub-channel cannot be normally received and demodulated, and an acknowledgment signal to the AP 10 cannot be returned.

  In this case, the AP 10 can cancel the transmission of the OFDMA frame to the terminal device 20-2 and release the radio resources of the second channel subchannel. As a result, interference with the terminal device 20-2 using the second CH can be reduced, and after the use of the second CH is completed, it can be allocated to another terminal device, so that effective scheduling can be expected. As a result, the throughput of the entire system can be improved.

  In the above, this invention was demonstrated based on the Example. The present invention is not limited to the above-described embodiments and the contents of each embodiment, and various modifications can be made within the scope of the gist of the present invention. The above-mentioned embodiment is an exemplification, and various modifications can be made to the combination of each component and each processing process by combining each embodiment, and such a modification is also within the scope of the present invention. Will be understood by those skilled in the art.

DESCRIPTION OF SYMBOLS 10 ... Access point apparatus, 20 ... Terminal device, 102 ... Transmission data buffer part, 104 ... OFDMA frame generation part, 106 ... MAP frame generation part, 108 ... Wireless transmission / reception part, 110 ... Control part, 202 ... Wireless transmission / reception part, 204 ... OFDMA frame analysis unit, 206 ... MAP frame analysis unit, 208 ... reception data buffer unit, 210 ... control unit.

Claims (13)

A data frame generation unit that generates a data frame by mapping transmission data for a terminal device using one or more frequency channels of a plurality of frequency channels;
A MAP frame generation unit that generates a MAP frame including information indicating a frequency channel to which transmission data generated by the data frame generation unit is mapped, and information indicating a terminal device that is a destination of the transmission data;
The MAP frame generated by the MAP frame generation unit is transmitted using a specific first frequency channel among the plurality of frequency channels, and then the data frame is transmitted using the frequency channel indicated by the MAP frame. A communication apparatus comprising: a transmission unit that transmits the data frame generated by the generation unit. The communication apparatus according to claim 1, wherein the transmission unit transmits the MAP frame and the data frame in different subframes. The transmitter is the same subframe as the MAP frame, and secures the frequency channel indicated in the MAP frame in one or more second frequency channels other than the first frequency channel. The communication apparatus according to claim 2, wherein the communication apparatus transmits a signal. The communication device according to claim 1, wherein the MAP frame generation unit includes information for clearly indicating that the MAP frame is a MAP frame. The MAP frame generation unit includes information on a scheduled time from a transmission timing of a data frame to a reception timing of an acknowledgment frame for transmission of the data frame in the MAP frame. The communication apparatus according to claim 1. The communication apparatus according to claim 1, wherein the MAP frame generation unit includes information for designating an acknowledgment procedure for transmission of a data frame in the MAP frame. The communication apparatus according to any one of claims 1 to 6, wherein the transmission unit transmits information specifying a frequency channel to be used for transmission of the MAP frame prior to the MAP frame. Using one or more frequency channels of a plurality of frequency channels to generate a data frame generated by mapping transmission data for the terminal device, information indicating the frequency channel to which the transmission data is mapped, and A MAP frame including information indicating a destination terminal device of transmission data is generated, the MAP frame is transmitted using a specific first frequency channel among a plurality of frequency channels, and then the MAP frame is transmitted to the MAP frame. A terminal device wirelessly connected to a communication device that transmits the data frame using the frequency channel indicated by:
A receiving unit for receiving the MAP frame and the data frame;
Whether there is data addressed to the own terminal device from information indicating a frequency channel to which transmission data included in the MAP frame received by the receiving unit is mapped and information indicating a terminal device that is a destination of the transmission data A MAP frame analysis unit for analyzing
A terminal device comprising: a data frame analysis unit that analyzes data addressed to the terminal device from a data frame received by the reception unit based on an analysis result of the MAP frame analysis unit. In the case where the information on the scheduled time from the transmission timing of the data frame to the reception timing of the acknowledgment frame for the transmission of the data frame is included in the MAP frame, the reception unit and the data frame analysis unit The terminal device according to claim 8, wherein when the analysis unit determines that there is no transmission data addressed to the terminal device, the operation is stopped until the scheduled time expires. When a frequency channel to be used for transmission of the MAP frame is specified prior to transmission of the MAP frame, the receiving unit identifies a frequency channel to receive the MAP frame based on information specifying the frequency channel. The terminal device according to claim 8, wherein the terminal device receives the signal. A data frame generation step of generating a data frame by mapping transmission data for the terminal device using one or more frequency channels of the plurality of frequency channels;
A MAP frame generation step for generating a MAP frame including information indicating a frequency channel to which the transmission data generated in the data frame generation step is mapped, and information indicating a destination terminal device of the transmission data;
The MAP frame generated in the MAP frame generation step is transmitted using a specific first frequency channel among the plurality of frequency channels, and then the data frame is transmitted using the frequency channel indicated in the MAP frame. A program for causing a computer to execute a transmission step of transmitting the data frame generated in the generation step. A communication method used in a communication system including a communication device and a terminal device wirelessly connected to the communication device,
In the communication device,
A data frame generation step of generating a data frame by mapping transmission data for the terminal device using one or more frequency channels of the plurality of frequency channels;
A MAP frame generation step for generating a MAP frame including information indicating a frequency channel to which the transmission data generated in the data frame generation step is mapped, and information indicating a destination terminal device of the transmission data;
The MAP frame generated in the MAP frame generation step is transmitted using a specific first frequency channel among the plurality of frequency channels, and then the data frame is transmitted using the frequency channel indicated in the MAP frame. Transmitting the data frame generated in the generating step, and
The terminal device
Receiving the MAP frame and the data frame;
Whether there is data addressed to the terminal device from information indicating the frequency channel to which the transmission data included in the MAP frame received in the reception step is mapped and information indicating the terminal device that is the destination of the transmission data MAP frame analysis step for analyzing
And a data frame analyzing step of analyzing data addressed to the terminal device from the data frame received in the receiving step based on an analysis result of the MAP frame analyzing step. A communication system comprising a communication device and a terminal device wirelessly connected to the communication device,
The communication device
A data frame generation unit that generates a data frame by mapping transmission data for a terminal device using one or more frequency channels of a plurality of frequency channels;
A MAP frame generation unit that generates a MAP frame including information indicating a frequency channel to which transmission data generated by the data frame generation unit is mapped, and information indicating a terminal device that is a destination of the transmission data;
The MAP frame generated by the MAP frame generation unit is transmitted using a specific first frequency channel among the plurality of frequency channels, and then the data frame is transmitted using the frequency channel indicated by the MAP frame. A transmission unit for transmitting the data frame generated by the generation unit,
The terminal device
A receiving unit for receiving the MAP frame and the data frame;
Whether there is data addressed to the own terminal device from information indicating a frequency channel to which transmission data included in the MAP frame received by the receiving unit is mapped and information indicating a terminal device that is a destination of the transmission data A MAP frame analysis unit for analyzing
A communication system comprising: a data frame analysis unit that analyzes data addressed to the terminal device from a data frame received by the reception unit based on an analysis result of the MAP frame analysis unit.

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