JP5120012B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND COMPUTER PROGRAM - Google Patents

Description

  The present invention relates to a communication apparatus and communication method for performing mutual communication between a plurality of wireless stations such as a wireless LAN (Local Area Network) or a PAN (Personal Area Network), and a computer program. The present invention relates to a communication apparatus and communication method in which a plurality of communication stations that operate in a peer-to-peer connection, and a computer program.

  More particularly, the present invention relates to a communication apparatus and a communication method that simultaneously participate in two or more wireless network systems having different logical network configurations and play a multiple role, and a computer program, in particular, an ad hoc network or The present invention relates to a communication apparatus and communication method having a dual role of a function as a communication station that operates autonomously and distributedly in a mesh network and a function as an access point in a network under an infrastructure mode, and a computer program.

  A wireless network is attracting attention as a system free from wiring in the conventional wired communication system. For example, a wireless LAN standard such as IEEE (The Institute of Electrical and Engineering Engineers) 802.11a, IEEE 802.11b, or IEEE 802.1g is typical. According to the wireless LAN, flexible Internet connection is possible. In addition to replacing the existing wired LAN, Internet connection means can be provided in public places such as hotels, airport lounges, stations, and cafes. Wireless LANs are already widely used, and it is common to install wireless LAN functions not only on information devices such as personal computers (PCs) but also on CE (Consumer Electronics) devices such as digital cameras and music players. It is becoming.

  In order to configure a LAN using wireless technology, a device serving as a control station called an “access point (AP)” or “coordinator” is provided in the area, and the network is under the overall control of this control station. The method of forming is generally used. The control station arbitrates access timings of a plurality of terminal stations in the network and performs synchronous wireless communication in which the terminal stations are synchronized with each other.

  As another method of configuring a wireless network, all terminal stations operate on peer-to-peer in an autonomous and distributed manner, and the terminal station itself determines access timing “ad hoc ( "Ad-hoc) communication" has been devised. Especially for small-scale wireless networks composed of a relatively small number of clients located in the vicinity, ad hoc communication that allows asynchronous communication directly between arbitrary terminals without using a specific control station is appropriate. It is thought that it is.

  For example, networking in IEEE 802.11 is based on the concept of BSS (Basic Service Set). The BSS is defined as an “infrastructure mode” in which a control station exists, and an IBSS defined in an “ad hoc mode” that includes only a plurality of MTs (Mobile Terminals: mobile stations or terminal stations). Independent BSS).

  In addition to ad hoc networks defined by IEEE 802.11, developments have been made on communication systems in which communication stations operating in an autonomous distributed manner are connected by peer-to-peer. For example, “multi-hop communication” in which a plurality of communication stations relay and transmit frames solves the problem that not all communication partners are accommodated in a range where radio waves can reach. Many communication stations can be interconnected by “multi-hop communication” in which frames are relayed and transmitted. Currently, as one of task groups (TG) in IEEE 802.11, standardization work related to multi-hop communication is in progress. In this specification, a wireless network that performs multi-hop communication is referred to as a “mesh network”, and each communication station that forms the mesh network is also referred to as a “mesh point (MP)”.

  First, the operation in the infrastructure mode in IEEE 802.11 will be described.

  Under the infrastructure mode, the AP collects a range where radio waves reach around its own station as a BSS and constitutes a so-called “cell” in a so-called cellular system. A terminal station (MT) existing in the vicinity of the AP is accommodated in the AP and enters the network as a member of the BSS. Specifically, the AP transmits a control signal called a beacon at an appropriate time interval, and the MT that can receive this beacon recognizes that the AP exists in the vicinity, and establishes a connection with the AP. To do.

  FIG. 11 shows an example of IEEE 802.11 operation in the infrastructure mode. In the illustrated example, the communication station STA0 operates as an AP, and the other communication stations STA1 and STA2 operate as MTs. As shown in the chart on the right side of the figure, the communication station STA0 as the AP transmits a beacon at regular time intervals. The AP internally manages the beacon transmission interval as a parameter called Target Beacon Transmit Time (TBTT), and starts the beacon transmission procedure every time the time arrives at the TBTT. The beacon notified by the AP includes a Beacon Interval field, and neighboring MTs can recognize the next beacon transmission time TBTT from the Beacon Interval field and the reception time of the beacon.

  Here, the BSS shifts to a power saving mode as necessary, and each MT performs a receiving operation only intermittently, thereby reducing power consumption. Under the power saving mode, at least some of the MTs in the BSS operate in the sleep mode, and go back and forth between an awake state in which the transceiver is operated and a doze state in which the power of the transceiver is turned off. Since the MT can recognize the next beacon transmission time from the received beacon, in the sleep mode, when there is no need for reception, the receiver is powered down until the next time or multiple times of the TBTT to enter the power saving state. May enter. Note that the MT that is not in the sleep mode is called an active mode, and always operates the transceiver (see FIG. 12).

  The AP centrally manages the timing at which each MT in the sleep state awakes, and assists the power saving operation by transmitting a frame to the MT in accordance with the timing of the awake state. Specifically, if there is a packet addressed to the MT in the sleep mode, the packet is not transmitted immediately, but is stored in the inside, and a message indicating that the packet is stored in the beacon signal is described. To tell. Information described in this beacon signal is called TIM (Traffic Indication Map). The MT in the sleep mode can recognize that the AP is accumulating data addressed to itself by receiving and analyzing the beacon signal from the AP and referring to the TIM. That is, when the MT in the power saving mode recognizes that it must perform a receiving operation, it sends a request signal to the AP to send a packet to the own station. Then, the AP transmits the accumulated data to the MT in response to this request signal.

  Next, an operation in the ad hoc mode in IEEE 802.11 will be described.

  In the ad-hoc mode (IBSS) of IEEE 802.11, the MT autonomously defines the IBSS when a plurality of MTs confirm the existence of each other. These MT groups define TBTT at regular intervals. The beacon transmission interval is notified by a parameter in the beacon signal, and each MT can calculate the next TBTT once it receives the beacon signal. When each MT recognizes that it has become TBTT by referring to the clock in its own station, if it recognizes that no one has transmitted a beacon after a random time delay (Random Backoff), the beacon Send. An MT that can receive this beacon can enter this IBSS.

  FIG. 13 shows an example of IEEE 802.11 operation in the ad hoc mode. In the illustrated example, two communication stations STA1 and STA2 operating as MTs form an IBSS. In this case, any one MT belonging to the IBSS transmits a beacon every time TBTT arrives. There is also a case where beacons transmitted from each MT collide.

  In IEEE 802.11, the IBSS also defines a power saving mode, and the MT can enter a Doze state in which the receiver is turned off as necessary. A predetermined time zone from the beacon transmission time TBTT is defined as an ATIM (Anonymous Traffic Indication Message) Window. Until the ATIM Window period ends, all MTs belonging to the IBSS are in the Awake state, and basically, MTs operating in the sleep mode can be received during this time period. It is. The MT can be in the Doze state from the end of the ATIM Window until the next beacon transmission time TBTT.

  In the case where each MT has information addressed to the own station, the own station holds the transmission information by transmitting an ATIM packet to the communication partner in the time zone of this ATIM Window. That the receiver is informed. On the other hand, the MT that has received the ATIM packet does not shift to the Doze state until the reception from the station that has transmitted the ATIM packet is completed, and operates the receiver.

  FIG. 14 shows an operation example when three MTs of STA1, STA2, and STA3 exist in the IBSS. When the MTTT of STA1, STA2, and STA3 arrives, the backoff timer is operated while monitoring the media state over a random time. In the illustrated example, the timer of STA1 expires earliest and STA1 transmits a beacon. Since STA1 has transmitted a beacon, STA2 and STA3 that have received the beacon do not transmit a beacon.

  Here, it is assumed that STA1 holds information addressed to STA2, and STA2 holds information addressed to STA3. In such a case, after the STA1 transmits the beacon, the STA2 receives the beacon, and then operates the back-off timer while monitoring each media state again for a random time. In the example shown in FIG. 14, since the timer of STA2 has been exposed first, an ATIM message is first transmitted from STA2 to STA3. Upon receiving this ATIM message, the STA 3 waits for a short frame interval (SIFS) and then returns an ACK (Acknowledge) packet indicating the reception to the STA 2. When the transmission of the ACK from the STA3 is completed, the STA1 further operates the back-off timer while monitoring the media state over a random time. When the timer is expired, the STA1 transmits an ATIM packet to the STA2. Then, after the SIFS has elapsed, STA2 returns an ACK packet indicating that the ATIM packet has been received to STA1.

  When such an ATIM packet and ACK packet are exchanged in the ATIM Window, STA3 operates the receiver to receive information from STA2 and STA2 also receives information from STA1 in the subsequent section. Operate the receiver to receive

  STA1 and STA2 holding transmission information wait for a distributed inter-frame space (DIFS) corresponding to the minimum time during which the medium is idle at the end of ATIM Window, and then wait for a random time. The backoff timer is activated while monitoring the status. In the example shown in FIG. 14, since the timer of STA2 has been exposed first, the data frame addressed to STA3 from STA2 is transmitted first. Then, after lapse of SIFS, STA3 returns an ACK packet indicating that the data frame has been received to STA2.

  After this data frame transmission is completed, STA1 waits for DIFS, and then operates the back-off timer again while monitoring the media state for a random time. When the timer expires, STA1 transmits the data frame addressed to STA2. To do. Then, after lapse of SIFS, STA2 returns an ACK packet indicating that the data frame has been received to STA1.

  In the above procedure, an MT that does not receive an ATIM packet in the ATIM Window and does not hold information to anyone can turn off the transmitter / receiver until the next TBTT to reduce power consumption. .

  Next, the operation of the mesh network will be described.

  For example, we propose a wireless communication system in which each communication station constructs a network by transmitting beacons describing information related to the network, and makes advanced judgments such as communication status at other communication stations using the beacon. (For example, see Patent Document 1), but a mesh network can be configured using a similar method.

  FIG. 15 shows a communication sequence example in a wireless communication system in which each communication station communicates in an autonomous and distributed manner through exchange of beacon signals. In the example shown in the figure, two communication stations, STA1 and STA2, that are in communication with each other exist in the communication range of each other, and each communication station sets its own TBTT (Target Beacon Transmission Time) and periodically Is sending a beacon signal. Each communication station periodically receives beacon signals from other communication stations as necessary in order to extract information on adjacent MTs.

  Here, it is assumed that the STA1 enters a sleep mode in which the power of the transceiver is turned off as necessary, and the MT in the power saving mode turns off the power of the transceiver and the awake state in which the transceiver is operated. Go back and forth between Doze states (same as above).

  FIG. 16 illustrates a state in which data transmission is performed from STA1 to STA0. The upper part of the figure shows the packet transmission / reception sequence between STA0 and STA1, and the lower part of the figure shows the operating state of the transceiver of STA0 which is the data receiving destination (level high indicates the awake state, level -Low indicates Doze state). Note that when any of the transceivers is in the Doze state, the communication station is in a power saving state, and when any of the transceivers is in the Awake state, it is a time period when the communication station is not in the power saving state.

  After transmitting a beacon, the MT provides a reception period (Listen Period) consisting of a certain time period, and the receiver is operated during this period. Then, when the MT does not receive traffic addressed to itself within the Listen Period, the MT can turn off the power of the transceiver and shift to the power saving state. In the example shown in FIG. 16, STA0 has operated the receiver for a while after transmitting beacon B0-0, and STA1 has transmitted a packet to STA0 within this period. Can be received.

  In the beacon signal, information called TIM (Traffic Indication Map) is posted. The TIM is broadcast information indicating to whom this communication station currently has information, and the beacon receiving station recognizes whether or not it must receive by referring to this TIM. be able to. Each MT periodically receives beacon signals from neighboring MTs, analyzes this TIM, and confirms that there is no data addressed to itself, and then turns off the receiver and enters a sleep state. If it is confirmed that the data exists, the sleep state is not entered, and a transition is made to a state where the data is received.

  FIG. 16 illustrates a case where STA0 is called from STA1 in the TIM of beacon B1-1. Upon receiving the beacon, STA0 makes a response in response to the call (0). Further, when the STA1 receiving the response confirms that the STA0 is in a receivable state, the STA1 transmits a packet addressed to the STA0 (1). The received STA0 transmits an ACK after confirming that it has been received normally (2).

  As indicated above, there can be several different logical network configurations in a wireless LAN system. In addition, one physical communication station can logically participate in a plurality of networks simultaneously, and is known as a dual-station communication station (dual roll device).

  FIG. 17 and FIG. 18 show how one physical communication station plays a dual role for two logical networks in a wireless LAN system composed of a plurality of different logical networks. Multiple different logical networks may be operated on the same frequency channel.

  In the example shown in FIG. 17, in a communication environment in which STA-A constitutes logical network A and STA-D constitutes logical network D, one communication station STA-C is physically connected to link A. Participates in network A via -C and at the same time participates in network D via link DC. At this time, both the network A and the network D operate in the infrastructure mode, and the STA-A and the STA-D may both operate as access points.

  On the other hand, in the example shown in FIG. 18, one network A may operate in an ad hoc mode or may be an autonomous distributed network such as a mesh network. In this case, the STA-C having the dual role operates as MT or MP in the other network A while communicating with the STA-D which is the access point as MT in the one network D. The communication stations STA-A and STA-B can directly communicate with each other.

  Here, regarding the merits of physically having one communication station having a dual role, the case where an autonomous decentralized network such as an ad hoc network or a mesh network and a network under an infrastructure mode are simultaneously joined. Consider for an example.

  In FIG. 18, it is assumed that STA-C is in communication with each other in the autonomous distributed communication mode with STA-A and STA-B, and an application such as a battle game is operating on these three communication stations. At this time, the STA-C is stored in a device such as a personal computer that is accommodated in the access point and has only the function of operating as an MT while continuing the battle game with the STA-A and the STA-B. A case is assumed where the game is controlled based on the information. In such a case, the STA-C continues to communicate with the STA-A and the STA-B in the autonomous distributed communication mode, and at the same time, operates as an access point under the infrastructure mode and is an MT STA-D. And necessary information can be acquired from the STA-D. If the communication station has a dual role and can participate in a plurality of logical networks at the same time as in the illustrated example, it is expected that various network services can be provided.

  In the example shown in FIG. 18, a communication station having a dual role can join both a network under ad hoc mode and a network under infrastructure mode and provide two logical communication interfaces. Such a communication station is convenient because it can communicate with peripheral communication stations belonging to different logical networks, but it is not necessary to keep all the logical communication interfaces all on, and the minimum necessary functions It is desired to keep it operating only. In particular, when operating as an access point, the communication station cannot operate in the power saving mode, so the problem of power consumption of the communication station becomes significant.

WO2004 / 071022

  An object of the present invention is to provide an excellent communication apparatus, communication method, and computer program that can play multiple roles suitably by simultaneously participating in two or more wireless network systems having different logical network configurations. There is.

  A further object of the present invention has a dual role of functioning as a communication station operating autonomously and distributedly in an ad hoc network or mesh network and functioning as an access point in a network under infrastructure mode, It is an object to provide an excellent communication apparatus, communication method, and computer program capable of simultaneously participating in a plurality of logical networks and providing various network services.

  A further object of the present invention is to have a dual role of a function as a communication station that operates autonomously and distributedly in an ad hoc network or a mesh network and a function as an access point in a network under an infrastructure mode. Another object of the present invention is to provide an excellent communication apparatus, communication method, and computer program that can save power consumption by appropriately operating only necessary functions.

The present invention has been made in consideration of the above problems, and the first aspect thereof is
A transmitter that transmits a radio signal;
A receiver for receiving a radio signal;
A terminal station function unit that operates as a terminal station in an autonomous distributed first network in which a plurality of communication stations are connected by peer-to-peer using the transmission unit and the reception unit;
An access point function unit that operates as an access point in the second network under the infrastructure mode using the transmission unit and the reception unit;
A state control unit that controls an on / off state of the access point function unit according to a communication status with a terminal station accommodated in the second network;
A communication device comprising:

  As a method for configuring a wireless network, an access point accommodates and operates a terminal station MT as in the infrastructure mode in IEEE 802.11, and all communication stations peer as peers in an autonomous and distributed manner as MTs or MPs. -A method of operating with a toe-peer is mentioned. Also, in a wireless LAN system composed of a plurality of different logical networks, a single physical communication station plays a dual role with respect to two logical networks, thereby participating in multiple logical networks at the same time. It is expected to be able to provide network services.

  In networking such as IEEE 802.11, a power saving mode is defined in each of the BSS and the IBSS, and a communication station serving as an MT can shift to the Doze state at an appropriate timing to achieve power saving of the apparatus. However, as long as the function as an access point is in the on state, the communication station STA-C having a dual role cannot shift to the sleep state even as an autonomously distributed MT or MP, and achieves power saving of the device. I can't do that.

  On the other hand, the communication device according to the present invention can operate as a communication station having a dual role, but does not always keep the function as an access point on, but operates only necessary functions as appropriate. To save power consumption.

  For example, the communication station turns on the function of the access point when it is recognized that there is a communication station that wants to communicate with the access point in the vicinity. For example, such recognition can be performed by receiving a probe request frame from a peripheral communication station operating as a terminal station in the infrastructure mode. Further, the communication station turns on the function as the access point because the function as the access point has not been turned on for a certain period of time. The communication station turns on the function as an access point in response to receiving a signal for searching for an access point from another communication station in a packet reception waiting state. In this way, by turning on the function as the communication station and, if necessary, the access point, various network services can be provided.

  On the other hand, if the communication station does not enter the communication state using the access point function for a certain period of time, although the beacon signal is periodically transmitted based on the access point function, the access point function Is turned off. In addition, the communication station does not enter the communication state using the access point function for a certain period of time after the communication state with the peripheral communication station that was communicating using the access point function is terminated. If an access point function occurs, the access point function is shifted to the off state. For example, it is possible to recognize that the communication state has been interrupted by receiving a signal intended for disassociation from the peripheral communication station. When the access point function is in the off state, the communication station can transition to the sleep state as MT, and can realize power saving.

According to a second aspect of the present invention, there is provided a computer program written in a computer-readable format so that a process for controlling a communication operation in a communication apparatus having a transmission / reception unit for transmitting / receiving a radio signal is executed on the computer And the computer
A terminal station function means for operating as a terminal station in an autonomous distributed first network in which a plurality of communication stations are connected by peer-to-peer using the transceiver unit;
An access point function means for operating as an access point in the second network under the infrastructure mode using the transceiver unit;
State control means for controlling an on / off state of the access point function unit according to a communication state with a terminal station accommodated in the second network;
It is a computer program for making it function as.

  The computer program according to the second aspect of the present invention defines a computer program described in a computer-readable format so as to realize predetermined processing on the computer. In other words, by installing the computer program according to the second aspect of the present invention in the computer, a cooperative action is exhibited on the computer, and the same action as the communication apparatus according to the first aspect of the present invention. An effect can be obtained.

  According to the present invention, it is possible to provide an excellent communication apparatus and communication method, and a computer program, which can simultaneously participate in two or more wireless network systems having different logical network configurations and can suitably play multiple roles. be able to.

  In addition, according to the present invention, the dual function of a function as a communication station that operates autonomously and distributedly in an ad hoc network or a mesh network and a function as an access point in a network under an infrastructure mode is provided. It is possible to provide an excellent communication apparatus, communication method, and computer program that can simultaneously participate in a plurality of logical networks and provide various network services.

  In addition, according to the present invention, it has a dual role of a function as a communication station that operates autonomously and distributedly in an ad hoc network or a mesh network and a function as an access point in a network under an infrastructure mode. In addition, it is possible to provide an excellent communication device, communication method, and computer program capable of reducing power consumption by appropriately operating only necessary functions.

  The communication device according to the present invention has a dual role of operating the network under the infrastructure mode as an access point at the same time as joining the network as an autonomous distributed MT or MP. On the contrary, when it is determined that the access point function is unnecessary, the access point function is shifted to the off state. As a result, it is possible to realize power saving while providing various network services.

  Other objects, features, and advantages of the present invention will become apparent from more detailed description based on embodiments of the present invention described later and the accompanying drawings.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The communication path assumed in the embodiment described below is wireless, and a network is used between a plurality of devices using a single transmission medium (when the link is not separated by a frequency channel). As a case to build. However, the same can be said even when a plurality of frequency channels exist as transmission media. Further, the communication assumed in the embodiment is a storage and exchange type traffic, and information is transferred in units of packets. In addition, the processing in each communication station described below is basically processing executed in all communication stations that enter the network. However, depending on the case, not all communication stations configuring the network execute the processing described below.

  FIG. 1 schematically shows a hardware configuration of a wireless device according to an embodiment of the present invention. The wireless device is an information device equipped with a wireless LAN card such as a personal computer, or a CE device such as a digital camera or a music player.

  The illustrated wireless device includes a CPU (Central Processing Unit) 1, a memory device such as a ROM (Read Only Memory) 2 and a RAM (Random Access Memory) 3, a peripheral device 4, and an external storage device such as a HDD (Hard Disk Drive). 5. Peripheral devices such as the wireless LAN interface 6 are interconnected via a bus. Two or more buses are connected via a bridge device.

  The CPU 1 loads the control code stored in the ROM 2 or the program code installed in the external storage device 5 onto the RAM 3 and executes it to execute device operation using the peripheral device 4 (for example, in a digital camera). The overall operation of the apparatus, such as shooting and image reproduction operations, playlist display and music reproduction operations in a music player, and communication operations using the wireless LAN interface unit 6 is comprehensively controlled.

  In the example shown in FIG. 1, the wireless LAN interface unit 6 passes a frame of an IEEE802.11 MAC (Media Access Control) layer to the RAM 3 via a bus, and the CPU 1 performs processing of the MAC layer. However, the gist of the present invention is not limited to the configuration of the radio apparatus as shown in FIG. 1, and another configuration as shown in FIG. 2 is also conceivable. In FIG. 2, the wireless LAN interface unit 6 is connected to the bus via the I / O interface 7. The I / O interface 7 that connects the wireless LAN interface unit 6 and the bus is generally MSIO (Memory Stick IO), SDIO (Secure Digital IO), USB (Universal Serial Bus), or the like. The wireless interface unit 6 performs processing of the IEEE 802.11 MAC (Media Access Control) layer, and sends a frame equivalent to IEEE 802.3 to the host CPU 1 through the I / O interface 7.

  The information equipment as shown in FIG. 1 and FIG. 2 is equipped with the wireless interface unit 6 so that, for example, a terminal station (Mobile terminal: MT) operating on an ad hoc network or a mesh terminal operating on a mesh network. It has a dual role of a function as an autonomous decentralized communication station such as a point (MP) and a function as an access point in the network under the infrastructure mode, and it is diverse by two logical communication interfaces. Network services can be provided. Multiple different logical networks may be operated on the same frequency channel. Further, the information equipment as shown in FIGS. 1 and 2 is assumed to be a battery-driven type in which driving power is supplied from a battery (not shown), and includes a charger for charging the battery, and the output of the battery The charging operation by the charger may be controlled by obtaining the remaining amount from the terminal voltage or the like.

  FIG. 3 shows an internal configuration example of the wireless interface unit 6. The illustrated wireless interface unit 6 operates as a terminal station in an autonomous decentralized communication environment in which no control station is arranged, and by effectively performing channel access within the same wireless system, the network can be operated while avoiding collisions. Can be formed. The wireless interface unit 6 can also function as an access point in the network under the infrastructure mode and has a dual role.

  As illustrated, the wireless interface unit 6 as a communication station includes a host interface unit 101, a data buffer 102, a central control unit 103, a beacon generation unit 104, a wireless transmission unit 106, a timing control unit 107, and the like. , An antenna 109, a wireless reception unit 110, a beacon analysis unit 112, and an information storage unit 113.

  The host interface unit 101 exchanges various kinds of information with a host device (see FIG. 1 or FIG. 2) connected to the I / O interface 7.

  The data buffer 102 temporarily stores data sent from the host device connected via the host interface unit 101 and data received via the wireless transmission path before sending the data via the host interface unit 101. Used to keep.

  The central control unit 103 centrally performs a series of information transmission and reception processing management and transmission path access control in the wireless interface unit 6 as a communication station by executing a predetermined execution command program.

  In this embodiment, the central control unit 103 realizes a dual role of a function as a communication station that operates in an autonomous distributed manner and a function as an access point in a network under an infrastructure mode, and performs two logical communications. Implement processing to provide a variety of network services through the interface.

  The beacon generation unit 104 generates a beacon signal that is periodically exchanged with a nearby communication station. In order for a wireless device including the wireless interface unit 6 to operate a wireless network, its own beacon transmission position and beacon reception position from an adjacent station are defined. The beacon time information is stored in the information storage unit 113 and posted in a beacon signal to notify an adjacent communication station. Since each communication station transmits a beacon at the beginning of the transmission frame period, the transmission frame period in the channel is defined by the beacon interval.

  The wireless transmission unit 106 performs predetermined modulation processing to wirelessly transmit data and beacon signals temporarily stored in the data buffer 102. The wireless reception unit 110 receives and processes signals such as information and beacons sent from other stations at a predetermined time.

  As a wireless transmission / reception method in the wireless transmission unit 106 and the wireless reception unit 110, various communication methods suitable for relatively short-distance communication applicable to a wireless LAN, for example, can be applied. Specifically, an Ultra Wide Band (UWB) system, an Orthogonal Frequency Multiplexing (OFDM) system, a Code Division Multiple Access (CDMA) system, or the like can be employed.

  The antenna 109 wirelessly transmits a signal addressed to another communication station on a predetermined frequency channel, or collects a signal arriving from another communication station. In this embodiment, it is assumed that a single antenna shared by the transceiver is provided, and that transmission and reception cannot be performed simultaneously.

  The timing control unit 107 controls timing for transmitting and receiving wireless signals. For example, it controls its own beacon transmission timing at the beginning of the transmission frame period, beacon reception timing from the adjacent station, data transmission / reception timing with the adjacent station, scanning operation period, and the like.

  The beacon analysis unit 112 analyzes a beacon signal received from an adjacent station, and analyzes the presence of a peripheral communication station including a hidden terminal. For example, beacon timing information of an adjacent station extracted from a beacon signal such as TBTT is stored in the information storage unit 113 as peripheral communication station information.

  The information storage unit 113 is a sequence of access control operations executed in the central control unit 103, such as execution procedure instructions (a program describing a collision avoidance processing procedure), peripheral communication station information obtained from the analysis result of the received beacon, etc. Save.

  The information device in FIG. 1 or FIG. 2 functions as an autonomously distributed communication station such as a terminal station operating on an ad hoc network or a mesh point operating on a mesh network, and under an infrastructure mode. It has a dual role of function as an access point in the network, and operates as a communication station that provides various network services through two logical communication interfaces. Further, it is not necessary to turn on all of the plurality of logical communication interfaces, and the power consumption can be reduced by operating with only the minimum necessary functions.

  FIG. 4 shows the state transition of such a communication station. However, in the figure, it is assumed that the communication station participates in both the network A and the network D as the communication station STA-C having a dual role in the communication system shown in FIG. In the following, regarding one communication station STA-C that participates in the network A as an autonomous distributed MT or MP, at the same time, a communication operation for operating the network D under the infrastructure mode as an access point, This will be described with reference to FIG.

  The communication station STA-C having a dual role changes between the idle state (State 1) and the packet reception standby state (State 9), and these states are switched back and forth mainly by timer control (state transition arrows 1 and 2). The event based on which the timer is controlled will be described in detail later.

  For example, it is assumed that the communication station STA-C is operating in the sleep mode as the MT and was initially in the idle state (State 1), but in order to enter the communication state with the communication station of the network A, the packet A reception standby state (State 9) is entered. The network A and the network D are operated on the same frequency channel, and the communication station STA-C waits for reception of packets from both the network A and the network D in the packet reception standby state (State 9).

  The communication station STA-C starts a beacon transmission process (State 2) for the network A when the time for transmitting a beacon to the network A is reached by timer control. When the transmission process ends, the communication station STA-C waits for packet reception (State 9). Return to (state transition arrows 3, 4).

  In addition, when a request for transmitting a packet addressed to a communication station in network A is generated, communication station STA-C activates a transmission process (State 3) issued to network A, and receives the packet when the transmission process is completed. Return to the standby state (State 9) (state transition arrows 5 and 6).

  When the communication station STA-C receives a packet from another communication station in the packet reception standby state (State 9), the communication station STA-C performs header check (State 5) of the received packet. Here, when the received packet is a packet from the communication station STA-A of the network A, a packet reception process (S4) from the network A is performed to return to the packet reception standby state (State 9) (state transition arrow 7, 10, 9). On the other hand, when the received packet is a packet from the communication station STA-D of the network D, a packet reception process (State 6) from the network D is performed to return to the packet reception standby state (State 9) (state transition arrows 7 and 11). 12).

  Further, the communication station STA-C activates a beacon transmission process (State 8) for the network D when the time for transmitting a beacon to the network D comes due to timer control or the like, and waits for packet reception when the transmission process ends. Return to state (State 9) (state transition arrows 16, 15).

  In addition, when a request for transmitting a packet addressed to a communication station in the network D is generated, the communication station STA-C activates a data transmission process (State 7) toward the network D, and waits for packet reception when the transmission process ends. Return to the state (State 9) (state transition arrows 13, 14).

  FIG. 5 shows the procedure of the header analysis processing of the received packet performed in the state S5 in the state transition diagram shown in FIG. 4 in the form of a flowchart. The processing routine is activated every time a packet is received from any of the peripheral communication stations in the packet reception standby state (State 9).

  When a communication station having a dual role receives a packet, it starts access control processing, first checks the destination of the received packet, and whether it is explicitly addressed to itself or to an unspecified number such as broadcast or multicast It is checked whether or not (step S1).

  If the destination of the received packet is explicitly addressed to itself or to an unspecified number of persons such as broadcast or multicast (Yes in step S1), it is determined that the packet is addressed to itself, and the process proceeds to the next step. move on. On the other hand, when it is determined that it is not addressed to itself (No in step S1), the process is terminated without performing the process of the received packet (step S5).

  Next, the communication station determines whether or not an error has occurred in the received packet (step S2). Note that this error determination may be performed before or after a destination check or a transmission source check. Even when it becomes clear that an error has occurred in the received packet (Yes in step S2), the process is terminated without performing the process on the received packet (step S5).

  If no error has occurred in the received packet (No in step S2), it is subsequently determined to which network the transmission source of the received packet belongs.

  Here, when the transmission source of the received packet is a transmission station of the network A (that is, another terminal station in the autonomous distributed network in which the local station participates as a terminal station) (Yes in step S3). ), The process proceeds to the state S4, and the reception process is performed as a packet received by the network A.

  If the transmission source of the received packet is a transmission station of the network D (that is, a terminal station accommodated in a network under an infrastructure mode operated by the local station as an access point) (step S4) Yes), the process proceeds to the state S6, where the packet is received as a packet received by the network D.

  If the transmission source does not belong to either network (No in step S4), frame processing in which the transmission source is unknown is performed as reception from a communication station that is not in communication with the local station (step S6).

  As described above, in the communication system shown in FIG. 18, the communication station STA-C participates in the network A as an autonomous distributed MT or MP, and simultaneously operates the network D under the infrastructure mode as an access point. . By the way, in IEEE 802.11, a power saving mode is defined in each of BSS and IBSS. MT enters a Doze state from the end of ATIM Window until the next beacon transmission time TBTT. On the other hand, since the AP centrally manages the timing at which each MT in the sleep state awakes, the AP cannot transition to the sleep state itself. For this reason, as long as the function as an access point is in the ON state, the communication station STA-C having a dual role cannot shift to the sleep state even as an autonomous decentralized MT or MP. It becomes impossible to plan.

  Therefore, in the present embodiment, the communication station STA-C having a dual role does not always keep the function as an access point on but always operates only necessary functions to save power consumption. ing.

  The communication station STA-C turns on the function of the access point when it is recognized that there is a communication station (MT such as STA-D) that wants to communicate with the access point in the vicinity.

  For example, the communication station STA-C turns on the function as the access point because it has not turned on the function as the access point for a certain time. Specifically, by periodically functioning as an access point and transmitting a beacon frame, a peripheral communication station such as STA-D can discover the network D by passive scanning.

  In response to receiving a signal for searching for an access point from another communication station in the packet reception standby state (State 9), the communication station STA-C turns on the function as the access point. Specifically, the signal for searching for an access point is a probe request signal transmitted from a peripheral communication station that performs active scanning. When the adjacent network A and the network D are operating on the same frequency channel, the communication station STA-A receives the Probe signal from the network D even if the network A is in a packet reception standby state (State 9). can do.

  Thus, the communication station STA-C having a dual role can provide various network services by turning on the function as an access point as necessary.

  On the other hand, the communication station STA-C does not enter the communication state using the access point function for a certain period of time, although the beacon signal is periodically transmitted to the network D based on the access point function. In the event of a failure, the access point function is shifted to the off state. In addition, the communication station STA-C is in a communication state in which other communication stations use the access point function over a certain period of time after the communication state with the peripheral communication station that has been communicating using the access point function is interrupted. When it does not enter, the access point function is shifted to the off state. When the access point function is in the off state, the communication station STA-C functions only as the MT and can shift to the sleep state, thereby realizing power saving.

  On / off control of the access point function of the communication station STA-C having a dual role will be described with reference to the state transition diagram shown in FIG.

  When the communication station STA-C having the dual role enters the communication state with the communication station of the network A, when the state shifts from the idle state (State 1) to the packet reception standby state (State 9), for example, the access point function is Assume that it is off. The communication station STA-C periodically turns on the access point function in accordance with the beacon transmission timing of the local station and performs a beacon transmission process for the network D (State 8). Thereby, peripheral communication stations such as STA-D can discover the network D by passive scanning.

  When the communication station STA-C receives the Probe signal from the network D in the packet reception standby state (State 9), the communication station STA-C performs a header check (State 5) on the received packet and confirms that it is a Probe signal addressed to itself. If recognized, the function as an access point is turned on.

  Of course, the communication station STA-C having the dual role turns on the access point function at the time of transition from the idle state (State 1) to the packet reception standby state (State 9), and accesses according to the subsequent behavior in the network D. The point function may be turned off.

  The communication station STA-C is assumed to be in a packet reception standby state (State 9) in both the network A and the network D with the access point function turned on. Then, the communication station STA-C performs a beacon transmission process (State 8) every beacon transmission cycle of the local station in order to enable passive scanning by the communication station in the network D. However, when the communication state using the access point function is not entered for a certain period of time, specifically, a packet reception process from the network D (State 6) or a data transmission process for the network D (State 7) is started. If there is no, the communication station STA-C turns off the access point function.

  Further, when receiving a packet from the network D, the communication station STA-C performs a packet reception process (State 6) through a header check (State 5) of the received packet, and returns to the packet reception standby state (State 9). Alternatively, the communication station STA-C activates a data transmission process (State 7) for the network D when a request to transmit a packet addressed to the communication station of the network D occurs, and waits for packet reception when the transmission process ends. Return to the state (State 9). Then, when the mobile station STA-C does not shift to either State 6 or State 7 for a certain period of time after moving to State 6 or State 7 and returning to the packet reception standby state (State 9), the communication station STA-C performs the access point function. Turn off.

  In FIG. 6, in the communication system shown in FIG. 18, the communication station STA-C joins the network A as an autonomous distributed MT or MP, and simultaneously operates the network D under the infrastructure mode as an access point. The example of a communication sequence in the case is shown. As shown in FIG. 18, STA-A belongs to network A and is in communication with STA-C and peer-to-peer. Further, STA-D belongs to network D as MT (terminal station), and is in communication with STA-C in which the access point function is turned on. However, it is assumed that the network A and the network D are operated on the same frequency channel.

  The communication station STA-A periodically transmits a beacon. In the communication sequence example shown in FIG. 6, STA-A transmits a beacon to network A at times T2 and T5.

  Further, the communication station STA-C also periodically transmits a beacon. In the communication sequence example shown in FIG. 6, the communication station STA-C transmits a beacon to the network A at times T3 and T6, and further transmits a beacon to the network D at times T1 and T4. .

  At this time, since the communication station STA-C operates as an access point in the network D, the communication station STA-C cannot enter the power saving operation, and it is necessary to always turn on the receiver when the frame is not transmitted. There is.

  7 shows an example of a communication sequence when the communication station STA-C turns off the access point function and puts the network D into a non-operating state from the state shown in FIG.

  The communication station STA-A periodically transmits a beacon. In the example shown in FIG. 7, a beacon is transmitted to the network A at times T2 and T5.

  Further, the communication station STA-C also periodically transmits a beacon. In the example shown in FIG. 7, only beacons addressed to network A are transmitted at times T3 and T6.

  The lower part of FIG. 7 shows activities that the communication station STA-C can take in the communication situation as described above. As already shown in FIG. 16 and the like, the communication station STA-C changes the transceiver to the active (Awake) state at the beacon transmission time of the communication station STA-A that is in communication with the network A, and transmits the beacon. After receiving, if it is determined that there is no traffic addressed to the own station, the state is again shifted to the idle state. In the communication sequence example shown here, the STA-C receives the beacon signal of the STA-A every time. However, in order to promote power saving, there are cases where the STA-C receives only once every several times. In the following, for simplification of explanation, a case where the communication station receives a beacon of an adjacent station every time will be described as an example, but such an operation is not necessarily required.

  In addition, the communication station STA-C changes the transceiver to the active state prior to the beacon transmission time of the local station. Then, after transmitting the beacon, the receiver is kept in an active state during the listen period. If nothing is received during this period, the receiver is again shifted to the idle state.

  In this way, in the communication sequence example shown in FIG. 7, since the communication station STA-C having the dual role turns off the access point function, the receiver is turned off in an unnecessary time zone. It becomes possible to make efforts to reduce power consumption.

  In the communication sequence example shown in FIG. 7, it is assumed that the network A operates in the mode of the autonomous distributed network, and each communication station STA-A and STA-C belonging to the network A periodically beacons. Is sending. Of course, the same can be said basically even when the network A is operating in the ad hoc mode. However, when network A is operating in ad hoc mode, both STA-A and STA-C do not regularly transmit beacons, but only one of them periodically transmits beacons. There is.

  The communication station STA-C having a dual role periodically transmits a beacon addressed to the network D when operating as an access point in the network D. On the other hand, when the network D does not operate as an access point, the STA-C can operate in the power saving mode without periodically transmitting a beacon addressed to the network D (same as above). In the following, for the sake of convenience, the case where the communication station STA-C operates in each mode of the autonomous distributed network and the infrastructure mode will be described as an example. However, the dual role of the STA-C in the ad hoc mode and the infrastructure mode is described. It should be appreciated that the exact same can be applied even when operating with.

  The communication station STA-C having a dual role shifts from the state where the function as an access point is not provided as shown in FIG. 7 to the state where the function as an access point is provided as shown in FIG. The trigger for this is the passage of time. The communication station STA-C uses an internal timer function to manage how many functions as an access point are not provided continuously. Then, if this time exceeds a certain time, MT such as STA-D may appear in the vicinity, so it is decided to start providing the function as an access point. After providing the function as an access point, in addition to the periodic beacon signal transmission / reception operation in the network A, the beacon signal addressed to the network D is also periodically transmitted as shown in FIG. .

  Thereafter, the communication station STA-C that provides the access point function may end the provision of the access point function again. The state transition will be described in detail later.

  In FIG. 8, the communication station STA-C shifts from the state where the function as an access point is not provided as shown in FIG. 7 to the state where the function as an access point is provided as shown in FIG. 6. An example of a communication sequence is shown. Further, the lower part of FIG. 8 shows temporal changes in the functions provided by the communication station STA-C.

  The communication station STA-C initially provides only the function of the mesh point in the autonomous distributed network A, receives the beacon of STA-A at time T2, and transmits the beacon of the local station at time T3. Yes.

  At this time, the STA-D wants to operate as an MT (terminal station), searches for a desired access point, and does not detect a probe request frame transmitted for the purpose of searching for an access point in the vicinity. Transmit to a specific number of communication stations. When the STA-C receives the probe request frame and recognizes that there is a communication station to be connected as an MT in the vicinity, the STA-C starts providing a function as an access point. At this time, the STA-C may make a probe response frame to the STA-D (not shown in FIG. 8) and explicitly indicate to the STA-D that an access point exists. Thereafter, STA-D and STA-C perform association, and then network D under the infrastructure mode shifts to a communication state. However, since the association procedure is well known in the art, a detailed description is omitted here.

  In this way, the communication station STA-C having a dual role also provides a function as an access point, so that the periodic transmission of the beacon signal to the network D is started thereafter. (That is, in the state transition diagram shown in FIG. 4, STA-C periodically starts the beacon transmission process (State 8) for network D from the packet reception standby state (State 9) by internal timer control) . The beacon transmitted from the STA-C at time T4 is a beacon signal addressed to the network D. STA-D can confirm that STA-C operating as an access point exists by receiving the beacon from STA-C.

  Thereafter, a communication sequence similar to that shown in FIG. 6 is performed. That is, STA-A transmits a beacon to network A at time T5, and STA-C also transmits a beacon addressed to network A at time T6 (activation of beacon transmission processing for network A (State 2)). Furthermore, at time T7, the STA-C transmits a beacon signal to the network D (activation of a beacon transmission process for the network A (State 8)).

  In FIG. 9, the communication station STA-C shifts from a state where the function as an access point is provided as shown in FIG. 6 to a state where the function as an access point is withdrawn as shown in FIG. 7. An example of a communication sequence is shown. Further, the lower part of FIG. 9 shows temporal changes in the functions provided by the communication station STA-C.

  STA-C initially provides both a mesh point function in network A and an access point function in network D. That is, STA-C transmits a beacon to network D at time T1, receives a beacon from STA-A (belonging to network A) at times T2 and T5, and transmits a beacon to network A at times T3 and T6. Sending.

  At this time, the STA-C is in a state where it does not enter a communication state with another communication station via the network D for a certain period of time, although it periodically transmits a beacon signal based on the function as an access point. Assume that there is. The STA-C decides to end the provision of the function as an access point after a certain period of time has passed without being in communication with any communication station via the network D. The function as an access point is to continue providing until the time T4 when the beacon should be transmitted next to the network D, without performing the beacon transmission at the time T4. Stop. After time T4, the state changes to the communication state as shown in FIG. When the access point function is in the OFF state, the STA-C can transition to the sleep state as the MT, and can realize power saving.

  When STA-C receives a signal (for example, a probe request frame) indicating that another communication station enters a communication state via network D until time T4, STA-C serves as an access point. Change the process to provide continuous functionality.

  In FIG. 10, the communication station STA-C shifts from the state in which the function as an access point is provided as shown in FIG. 6 to the state in which the function as an access point is withdrawn as shown in FIG. The other communication sequence example for this is shown. Also, the lower part of FIG. 10 shows temporal changes in the functions provided by the communication station STA-C.

  The STA-C initially provides both the function of the mesh point in the network A and the function of the access point in the network D, transmits a beacon to the network D at the time T1, and transmits the beacon to the STA-A at the times T2 and T5. A beacon (belonging to network A) is received and a beacon is transmitted to network A at times T3 and T6.

  At this time, the STA-C has received a message intended for disassociation (association abortion: indicated as Disass in the figure) from the STA-D that is in the communication state only in the network D under the infrastructure mode. Thus, STA-D explicitly cancels the communication state.

  Since the STA-C has lost communication with any communication station via the network D due to the reception of the Disss message, the STA-C starts the timer in response to this. And STA-C stops the function as an access point when this timer expires.

  After STA-C stops the access point function, it shifts to the communication state as shown in FIG. When the access point function is in the OFF state, the STA-C can transition to the sleep state as the MT, and can realize power saving.

  Note that, when the STA-C receives a signal (for example, a probe request frame) indicating that another communication station enters a communication state via the network D until the access point function is actually stopped. The process is changed so that the function as an access point is continuously provided.

  The present invention has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiment without departing from the gist of the present invention.

  In the present specification, the embodiment applied to a wireless LAN system such as IEEE802.11 has been mainly described, but the gist of the present invention is not limited to this. The present invention can be similarly applied to various types of wireless communication environments composed of several different logical network configurations.

  In short, the present invention has been disclosed in the form of exemplification, and the description of the present specification should not be interpreted in a limited manner. In order to determine the gist of the present invention, the claims should be taken into consideration.

FIG. 1 is a diagram schematically illustrating a hardware configuration of a wireless device according to an embodiment of the present invention. FIG. 2 is a diagram schematically illustrating a hardware configuration of a wireless device according to another embodiment of the present invention. FIG. 3 is a diagram illustrating an internal configuration example of the wireless interface unit 6. FIG. 4 is a state transition diagram of a communication station having a dual role of a function as a communication station that operates in an autonomous distributed manner and a function as an access point in a network under an infrastructure mode. FIG. 5 is a flowchart illustrating a procedure of header analysis processing of a received packet performed in state S5 in the state transition diagram illustrated in FIG. FIG. 6 is a diagram illustrating a communication sequence example performed by each communication station participating in each network when the autonomous distributed network and the network under the infrastructure mode are adjacent to each other. FIG. 7 is a diagram showing a communication sequence example when the communication station STA-C turns off the access point function and puts the network D into the non-operating state from the state shown in FIG. 8 shifts from the state where the communication station STA-C does not provide the function as the access point as shown in FIG. 7 to the state where the function as the access point is provided as shown in FIG. It is the figure which showed the example of a communication sequence. FIG. 9 shows communication in which the communication station STA-C shifts from a state in which the function as an access point is provided as shown in FIG. 6 to a state in which the function as an access point is withdrawn as shown in FIG. It is the figure which showed the example of a sequence. FIG. 10 shows that the communication station STA-C shifts from the state in which the function as an access point is provided as shown in FIG. 6 to the state in which the function as an access point is withdrawn as shown in FIG. It is the figure which showed the other example of a communication sequence. FIG. 11 is a diagram illustrating an operation example of IEEE802.11 in the infrastructure mode. FIG. 12 is a state transition diagram for explaining a power saving operation of a communication station operating as an MT. FIG. 13 is a diagram illustrating an example of IEEE 802.11 operation in the ad hoc mode. FIG. 14 is a diagram illustrating an operation example when three MTs of STA1, STA2, and STA3 exist in the IBSS. FIG. 15 is a diagram illustrating a communication sequence example in a wireless communication system in which each communication station communicates in an autonomous distributed manner through exchange of beacon signals. FIG. 16 is a diagram illustrating a state in which data transmission is performed from STA1 to STA0 and an operation state of a transceiver of STA0 that is a data reception destination. FIG. 17 is a diagram illustrating a state in which one physical communication station plays a dual role for two logical networks in a wireless LAN system including a plurality of different logical networks. FIG. 18 is a diagram illustrating a state where one physical communication station plays a dual role for two logical networks in a wireless LAN system including a plurality of different logical networks.

Explanation of symbols

1 ... CPU
2 ... ROM
3 ... RAM
DESCRIPTION OF SYMBOLS 4 ... Peripheral device 5 ... External storage device 6 ... Wireless LAN interface part 7 ... I / O interface 101 ... Host interface part 102 ... Data buffer 103 ... Central control part 104 ... Beacon generation part 106 ... Wireless transmission part 107 ... Timing Control unit 109 ... antenna 110 ... radio reception unit 112 ... beacon analysis unit 113 ... information storage unit

Claims (8)

A transmitter that transmits a radio signal;
A receiver for receiving a radio signal;
A terminal station function unit that operates as a terminal station in an autonomous distributed first network in which a plurality of communication stations are connected by peer-to-peer using the transmission unit and the reception unit;
An access point function unit that operates as an access point in the second network under the infrastructure mode using the transmission unit and the reception unit;
When participating in both the first network and the second network, the access point function unit is turned on / off according to the communication status with the terminal station accommodated in the second network. A state control unit for controlling
Equipped with,
The access point function unit periodically transmits a beacon signal to the second network in an on state,
When the state control unit does not enter a communication state using the access point function unit for a certain period of time, the state control unit shifts the access point function unit to an off state,
A communication device. The state control unit turns on the access point function unit when it is recognized that there is a terminal station that wants to communicate with the access point in the second network.
The communication apparatus according to claim 1. The state control unit turns on the access point function unit because the access point function unit has not been turned on for a certain period of time.
The communication apparatus according to claim 1. In response to receiving a signal for searching for an access point from a terminal station in the second network, the state control unit turns on the access point function unit.
The communication apparatus according to claim 1. The state control unit communicates using the access point function unit over a certain period of time after the communication state with the terminal station in the second network that was communicating using the access point function unit is terminated. When not entering the state, the access point function unit is shifted to the off state.
The communication apparatus according to claim 1. A power saving control unit that controls a power saving operation of the transmitting unit or the receiving unit according to communication activity in the first network in the off state of the access point function unit;
The communication apparatus according to claim 1. A terminal station function step that operates as a terminal station in a first autonomous distributed network in which a plurality of communication stations are connected by peer-to-peer;
An access point functional step operating as an access point in the second network under infrastructure mode;
Controls activation of the access point function step according to the communication status with a terminal station accommodated in the second network when participating in both the first network and the second network. A state control step;
Have
In the access point function step, a beacon signal is periodically transmitted to the second network when the access point function is on,
The state control step shifts the access point function to an off state when the communication state using the access point function is not entered for a certain period of time.
A communication method characterized by the above. A computer program written in a computer-readable format so as to execute processing for controlling a communication operation in a communication device including a transmission / reception unit for transmitting / receiving a radio signal on a computer, the computer comprising:
A terminal station function means for operating as a terminal station in the first autonomous distributed network in which a plurality of communication stations are connected by peer-to-peer using the transceiver unit;
Access point function means for operating as an access point in the second network under the infrastructure mode using the transceiver unit;
When participating in both the first network and the second network, the access point function unit is turned on / off according to the communication status with the terminal station accommodated in the second network. State control means for controlling
Function as
The access point function unit periodically transmits a beacon signal to the second network in an on state,
When the state control unit does not enter a communication state using the access point function unit for a certain period of time, the state control unit shifts the access point function unit to an off state,
A computer program characterized by the above.

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