JP2005236819A - Wireless communication system, device, and method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable each communication station to manage connection relations to a network by a simple method in an autonomous distributed type network. <P>SOLUTION: A beacon signal transmitted almost periodically is exchanged mutually. Address information for identifying a wireless communication device and operation state information showing the operation state of the wireless communication device are included in a beacon signal. Consequently, entry processing to the network is simplified. The communication stations each other, which reject the connection, do not execute connection information transmission at a high-order layer as a member of the network. However, the communication stations each other grasp and manage the mutual existence as a peripheral station. Disassociation processing of a communication station, which cannot receive the beacon signal, is executed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication system, a wireless communication apparatus, a wireless communication method, and a computer program for performing mutual communication between a plurality of wireless stations such as a wireless LAN (Local Area Network), and in particular, a specific control station. The present invention relates to a wireless communication system, a wireless communication apparatus, a wireless communication method, and a computer program in which each communication station performs a network operation in an autonomous and distributed manner without disposing a network.

  More specifically, the present invention relates to a wireless communication system, a wireless communication apparatus and a wireless communication method, and a computer program, in which each communication station manages a connection relation to the network by a simple method in an autonomous distributed network. In particular, the present invention relates to a wireless communication system, a wireless communication apparatus and a wireless communication method, and a computer program for managing the association state of each communication station to the network in a simple procedure in an autonomous distributed network.

  Information network sharing and device resource sharing can be efficiently realized by computer networking such as a LAN. Here, a wireless LAN is attracting attention as a system for releasing users from the conventional wired LAN connection. According to the wireless LAN, most of the wired cables can be omitted in a work space such as an office, so that a communication terminal such as a personal computer (PC) can be moved relatively easily.

  In recent years, the demand for wireless LAN systems has increased remarkably with the increase in speed and cost. In particular, recently, in order to establish a small-scale wireless network between a plurality of electronic devices existing around a person and perform information communication, introduction of a personal area network (PAN) has been studied. For example, different wireless communication systems are defined using frequency bands that do not require a license from a supervisory authority, such as 2.4 GHz band and 5 GHz band.

  One standard for wireless networks is IEEE (The Institute of Electrical and Electronics Engineers) 802.11 (for example, see Non-Patent Document 1), HiperLAN / 2 (for example, Non-Patent Document 2 or Non-Patent Document 2 or Non-Patent Document 2). (See Patent Document 3), IEEE 302.15.3, Bluetooth communication, and the like. Regarding the IEEE802.11 standard, there are extended standards such as IEEE802.11a (see, for example, Non-Patent Document 4), b, and g, depending on the wireless communication method and the frequency band to be used.

  In general, in order to configure a local area network using wireless technology, a device serving as a control station called an “access point” or “coordinator” is provided in the area. A method of forming a network under comprehensive control is used.

  In a wireless network in which an access point is arranged, when information is transmitted from a certain communication device, a bandwidth necessary for the information transmission is first reserved in the access point so that there is no collision with information transmission in another communication device. In this way, an access control method based on bandwidth reservation that uses a transmission line is widely adopted. That is, by arranging access points, synchronous wireless communication is performed in which communication devices in a wireless network are synchronized with each other.

  However, when asynchronous communication is performed between the communication device on the transmission side and the reception side in a wireless communication system in which an access point exists, wireless communication via the access point is always required. There is a problem that the efficiency is halved.

  On the other hand, as another method of configuring a wireless network, “ad-hoc communication” in which terminals perform wireless communication directly and asynchronously has been devised. In particular, in a small-scale wireless network composed of a relatively small number of clients located in the vicinity, ad-hoc communication that allows any terminal to perform asynchronous wireless communication directly without using a specific access point is provided. It seems to be appropriate.

  In an autonomous decentralized ad hoc network, a network is formed with wireless communication devices around it, and a wireless communication device that requires communication according to an instruction from an application of a device connected to the wireless communication device. On the other hand, a method of transmitting predetermined information is used.

  Since an ad hoc wireless communication system does not have a central control station, it is suitable for configuring a home network made up of household electrical devices, for example. In an ad hoc network, even if one unit fails or power is turned off, the routing is automatically changed so that the network is unlikely to break down. The high data rate can be maintained by hopping packets between mobile stations multiple times. There is a feature that data can be transmitted to a relatively long distance. Various development cases are known for ad hoc systems (for example, see Non-Patent Document 5).

  For example, in an IEEE802.11 wireless LAN system, networking in IEEE802.11 is based on the concept of BSS (Basic Service Set).

  The BSS is an “ad hoc” composed of only a BSS defined by an “infrastructure mode” in which a master such as an AP (Access Point) exists and a plurality of mobile stations (Mobile Terminals). It is composed of two types of IBSS (Independent BSS) defined in “Mode”. In the latter ad hoc mode, operation is performed in a peer-to-peer manner in an autonomous and distributed manner without providing a control station. When the beacon transmission time is reached, each terminal counts a random period, and when it does not receive a beacon of another terminal by the end of the period, it transmits a beacon.

  In the infrastructure mode BSS, an access point for coordinating in the wireless communication system is essential. That is, the access point collects the range where radio waves reach around its own station as a BSS, and constitutes a “cell” in what is called a cellular system. A mobile station existing in the vicinity of the access point is accommodated in the access point and enters the network as a member of the BSS.

  The access point transmits a control signal called a beacon at an appropriate time interval, and a mobile station capable of receiving this beacon recognizes that the access point exists in the vicinity, and further establishes a connection with the access point. Establish. On the other hand, mobile stations around the access point can recognize the next beacon transmission time by decoding the internal TBTT field by receiving a beacon. If this is not necessary, the receiver may be turned off and enter a sleep state until the next time or until several times later.

  In the infrastructure mode, only the access point transmits a beacon at a predetermined frame period. On the other hand, the peripheral mobile station joins the network by receiving a beacon from the access point, and does not transmit a beacon.

  On the other hand, in IBSS in ad hoc mode, IBSS is autonomously defined after negotiation between a plurality of mobile stations. When IBSS is defined, the mobile station group determines TBTT at regular intervals at the end of the negotiation. When each mobile station recognizes that the TBTT has arrived by referring to the clock in its own station, it transmits a beacon when it recognizes that no one has yet transmitted a beacon after a random time delay.

  In general, when a network is configured by assembling a plurality of wireless communication apparatuses, an infrastructure mode is used, and each communication station is connected under the access point. Under infrastructure mode, communication stations exchange predetermined messages with each other to connect to an access point. A network entry method, that is, an association procedure is defined in which only a communication station that is permitted to connect is connected to an access point to form a network. In addition, when leaving the network, an operation of leaving the network is defined by performing a disassociation operation with the coordinator (see, for example, Non-Patent Document 6).

  In recent years, high-speed wireless personal area networks have been put into practical use, and standardization work is mainly performed in IEEE 802.15.3. Here, one of the wireless communication devices that make up the network operates as a control station called a coordinator, and the wireless communication devices that exist in the vicinity define an operation to enter the network by performing an association operation with the coordinator. Has been.

  On the other hand, the ad hoc mode is a mode in which specific communication stations within a direct communicable station connect with each other on a peer-to-peer basis, and an access point is arranged or other communication existing in the wireless network is performed. Since it is not necessary to grasp the existence of the device, communication can be easily performed (described above). For this reason, a network entry method such as an association / disassociation procedure prepared in the infrastructure mode has not been necessary in the past.

International Standard ISO / IEC 8802-11: 1999 (E) ANSI / IEEE Std 802.11, 1999 Edition, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layers (PH) ETSI Standard ETSI TS 101 761-1 V1.3.1 Broadband Radio Access Networks (BRAN); HIPERLAN Type 2; Data Link Control (DLC) Layer; Part1: BasicControl ETSI TS 101 761-2 V1.3.1 Broadband Radio Access Networks (BRAN); HIPERLAN Type 2; Data Link Control (DLC) Layer; Part2: Radio Link Control (LC) Supplement to IEEE Standard for Information technology-Telecommunications and information exchange between systems-Local and metropolitan area networks-Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: High-speed Physical Layer in the 5GHZ Band C. K. “Ad Hoc Mobile Wireless Network” by Thor (published by Prentice Hall PTR) Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specification IEEE Std 802.11-1997 (Page 25 5.7.2 Association, 5.7.3.7.3.7.3.7.

  In a conventional wireless LAN system, an access point needs to always receive and manage information from a communication station existing under its control, and the processing is more complicated than that of a normal communication station.

  On the other hand, in a conventional ad hoc network, information is directly passed between peer communication stations existing in the vicinity through a peer-to-peer connection. For this reason, an association procedure with the access point is not prepared.

  However, even in an autonomous decentralized ad hoc network, in order to manage each communication station, processing similar to the association procedure as a method of entering a network prepared as an infrastructure mode in a wireless LAN system is performed. We believe that it is necessary.

  For example, in a high-speed wireless PAN compliant with IEEE 802.15.3, signals cannot be exchanged within the network unless each communication station performs a predetermined association procedure with the coordinator. For this reason, for example, a radio communication apparatus that is an interference source of a certain network must take a countermeasure against interference by following a predetermined association procedure.

  When this is applied to an autonomous decentralized ad hoc network, each communication station needs a procedure for grasping peripheral stations existing in the vicinity of the own station and constantly grasping their operation states.

  In particular, when an associated communication station is removed from the network, a disassociation message must be exchanged. In an autonomous distributed network, a message is exchanged with all communication stations existing on the network. Must be replaced.

  For this reason, the communication station always performs a reception operation, and if there is a change, it must start the association procedure again and rejoin the ad hoc network, which makes the device operation process considerably complicated. .

  In addition, unlike a wired connection such as a cable, a wireless link does not always guarantee a connection state of 100%. For example, when the radio wave propagation state temporarily deteriorates and the connection is interrupted and the connection is established again, the association operation must be performed again. For this reason, the process of performing the association procedure becomes more complicated and the processing load becomes excessive.

  Furthermore, in an ad hoc network, even if communication stations refused connection between users (or higher layers of the communication protocol), after the connection is restored, a predetermined association operation is performed again, and then the user ( Alternatively, it is necessary to take a procedure for rejecting the connection between the upper layers of the communication protocol.

  The present invention has been made in view of the technical problems described above, and its main purpose is to provide excellent wireless communication that allows each communication station to perform network operations in an autonomous and distributed manner without arranging a specific control station. A communication system, a wireless communication apparatus, a wireless communication method, and a computer program are provided.

  A further object of the present invention is to provide an excellent wireless communication system, wireless communication apparatus and wireless communication method, and computer, in which each communication station can manage the connection relation to the network by a simple method in an autonomous distributed network.・ To provide a program.

  A further object of the present invention is to provide an excellent wireless communication system, wireless communication apparatus and wireless communication method, and computer capable of managing the association state of each communication station to the network in a simple procedure in an autonomous distributed network.・ To provide a program.

The present invention has been made in consideration of the above problems, and a first aspect thereof is a wireless communication system in which each communication station performs network operation in an autonomous and distributed manner without arranging a specific control station. ,
Each communication station broadcasts an association message at a predetermined cycle, and receives the broadcasted association message to detect the state of the communication station existing in the vicinity, and configures an autonomous distributed network To figure out,
This is a wireless communication system.

  However, “system” here refers to a logical collection of a plurality of devices (or functional modules that realize specific functions), and each device or functional module is in a single housing. It does not matter whether or not.

  According to the present invention, in the present invention, each communication station broadcasts an association message at a predetermined cycle and receives the broadcasted association message to detect the state of communication stations existing in the vicinity. It is possible to grasp the communication stations constituting the autonomous distributed network.

  By including address information, capability information, attribute information, operating status, and presence information of surrounding communication devices in this association message, the communication station that has received the association message immediately determines the operation status of the surrounding communication stations. I can grasp it.

  Further, the communication station can simplify the association process in the autonomous distributed network by managing the address information included in the received association message as the association state.

  In addition, the communication station can define the disassociation process in a non-procedural manner by canceling the association state of the peripheral station that has become unable to receive the association message.

According to a second aspect of the present invention, there is provided a computer program written in a computer-readable format so as to execute processing for performing data transmission on a computer system in a wireless communication environment in which no specific control station is arranged. Because
An association message sending step for sending an association message describing information about the own station;
An association message receiving step for receiving and analyzing an association message from a peripheral station;
A network connection relation management step for detecting the state of communication stations existing in the vicinity based on the analysis result of the association message and grasping the communication stations constituting the autonomous distributed network;
A computer program characterized by comprising:

  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 a computer system. In other words, by installing the computer program according to the second aspect of the present invention in the computer system, a cooperative action is exhibited on the computer system, and it operates as a wireless communication device. By activating a plurality of such wireless communication devices to construct a wireless network, it is possible to obtain the same effects as the wireless communication system according to the first aspect of the present invention.

  According to the present invention, there is provided an excellent wireless communication system, wireless communication apparatus and wireless communication method, and computer program capable of allowing each communication station to perform network operation in an autonomous and distributed manner without arranging a specific control station. Can be provided.

  In addition, according to the present invention, in an autonomous distributed network, each communication station can manage the connection relation to the network by a simple method, an excellent wireless communication system, a wireless communication device, a wireless communication method, and A computer program can be provided.

  According to the present invention, a simple association procedure in an autonomous distributed ad hoc network can be provided. That is, communication stations can have a network connection relationship and manage the association state by simply exchanging association messages without taking the conventional association procedure. Furthermore, it is possible to simplify the disassociation procedure by defining a mechanism for automatically canceling the association state when communication with the wireless communication apparatus once in the association state becomes impossible.

  According to the present invention, for example, in an autonomous distributed network that is operated by each communication station informing a beacon at a predetermined cycle and recognizing each other, the communication station is configured to receive its own address information and current operation status. Can be included in the beacon information, and the ad hoc network entry process can be easily performed only by exchanging beacon information without performing an association procedure as in the prior art.

  In addition, according to the present invention, communication stations, including communication stations that cannot be entered or cannot be authenticated in the course of association or authentication processing depending on an upper layer or an application, between surrounding wireless communication devices The network can be managed in an autonomous and distributed manner.

  Further, according to the present invention, the communication station can perform a disassociation process that automatically cancels the association state when the signal from the wireless communication apparatus that is once in the association state is interrupted.

  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 propagation path assumed in the present invention is wireless, and a network is constructed between a plurality of communication stations. The communication assumed in the present invention is a storage and exchange type traffic, and information is transferred in units of packets. In the following description, each communication station assumes a single channel. However, the communication station can be extended when a transmission medium including a plurality of frequency channels, that is, multi-channels is used.

  The wireless network system according to the present invention has an autonomous distributed system configuration in which no specific control station is arranged, and channel resources are effectively used by transmission (MAC) frames having a gradual time division multiple access structure. The transmission control is performed. Each communication station can also directly and asynchronously transmit information according to an access procedure based on CSMA (Carrier Sense Multiple Access).

  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 configuration of an autonomous distributed network according to a position embodiment of the present invention. In the illustrated network, a plurality of wireless communication devices are arranged in space such as communication device # 1 to communication device # 7, and can directly communicate with communication devices existing in the vicinity.

  Here, the communication device # 1 can directly communicate with neighboring communication devices # 2, # 3, and # 4 in the radio wave reachable range 11 (within the elliptical broken line centering on # 1), but outside the range. The communication devices # 5, # 6, and # 7 cannot directly communicate.

  Communication device # 2 can directly communicate with neighboring communication devices # 1, # 4, but cannot communicate directly with other communication devices # 3, # 5, # 6, # 7.

  Communication device # 3 can directly communicate with neighboring communication devices # 1, # 6, and # 7, but cannot communicate directly with other communication devices # 2, # 4, and # 5.

  Communication device # 4 can directly communicate with neighboring communication devices # 1, # 2, and # 5, but cannot communicate directly with other communication devices # 3, # 6, and # 7.

  Further, the communication device # 5 can directly communicate only with the communication device # 4 in the vicinity, but cannot directly communicate with the other communication devices # 1, # 2, # 3, # 6, and # 7.

  In addition, the communication device # 6 can directly communicate only with the nearby communication device # 3, but cannot communicate directly with the other communication devices # 1, # 2, # 4, # 5, and # 7.

  In addition, the communication device # 7 can directly communicate only with the nearby communication device # 3, but cannot directly communicate with other communication devices # 1, # 2, # 4, # 5, and # 6.

  As in this embodiment, in an autonomous decentralized wireless communication system in which no control station is particularly arranged, each communication station broadcasts beacon information on the channel to other communication stations in the vicinity (that is, within the communication range). In addition to letting you know your existence, it notifies you of the network configuration. Since the communication station transmits a beacon at the beginning of the transmission frame period, the transmission frame period is defined by the beacon interval. In addition, each communication station scans the channel for a period corresponding to the transmission frame period, thereby discovering a beacon signal transmitted from a peripheral station and decoding the information described in the beacon. Can know. In this specification, the transmission frame period that is a beacon transmission interval is referred to as a “super frame (T_SF)”.

  Each communication station synchronizes gently while listening to beacons transmitted in the vicinity. When a new communication station appears, the new communication station sets its own beacon transmission timing so that it does not collide with the beacon transmission timing of the existing communication station.

  Each communication station uses its own beacon transmission timing as the head position of the super frame. In other words, each communication station sets its own super frame configuration so that the start timing does not overlap with the super frame configuration of neighboring stations.

  For example, if the super frame is 40 milliseconds and the information transmitted by the beacon is 100 bytes, the time required for transmission is 18 microseconds. Since transmission is performed once every 40 milliseconds, the media occupation rate of the beacon for each communication station is as small as 1/22222.

  In the autonomous decentralized network according to the present embodiment, a procedure in which each communication station performs beacon transmission within a superframe will be described with reference to FIG.

  In the illustrated example, the wireless communication device # 1 receives the beacon signals (N2, N3, and N4) of the neighboring communication devices # 2, # 3, and # 4 and at a timing that does not overlap with the beacon signals. A beacon signal (B1) is transmitted, and the period until the next beacon signal transmission timing (B1 ′) is set to its own superframe period.

  Similarly, the communication device # 2 can receive the beacon signals (N1, N4) of the communication devices # 1, # 4 in the vicinity. Further, the communication device # 3 can receive the beacon signals (N1, N6, N7) of the communication devices # 1, # 6, and # 7 in the vicinity of the own station. Further, the communication device # 4 can receive the beacon signals (N1, N2, N5) of the communication devices # 1, # 2, and # 5 in the vicinity of the own station. Also, the communication device # 5 can receive the beacon signal (N4) of the communication device # 4 in the vicinity of the own station. Further, the communication device # 6 can receive the beacon signal (N3) of the communication device # 3 in the vicinity of the own station. Further, the communication device # 7 can receive the beacon signal (N3) of the communication device # 3 in the vicinity of the own station.

  Thereafter, the communication station that newly enters the communication range sets its own beacon transmission timing so as not to collide with the existing beacon arrangement.

  FIG. 3 shows a state in which the association operation is performed by exchanging beacon signals between the wireless communication devices forming the network.

  Association information included in the beacon signal of communication device # 1 is received by communication devices # 2, # 3, and # 4, and association information such as address information and attribute information of communication device # 1 is distributed to each communication device. The

 Similarly, association information included in the beacon signal of communication device # 2 is received by communication devices # 1 and # 4, and association information such as address information and attribute information of communication device # 2 is distributed to each communication device. The

 The association information included in the beacon signal of communication device # 3 is received by communication devices # 1, # 6, and # 7, and association information such as address information and attribute information of communication device # 3 is received in each communication device. Distributed.

  Also, the association information included in the beacon signal of the communication device # 4 is received by the communication devices # 1, # 2, and # 5, and association information such as address information and attribute information of the communication device # 4 is received in each communication device. Distributed.

  Also, the association information included in the beacon signal of the communication device # 5 is received only by the communication device # 4, and association information such as address information and attribute information of the communication device # 5 is distributed only to the communication device # 4.

  The association information included in the beacon signal of communication device # 6 is received only by communication device # 3, and association information such as address information and attribute information of communication device # 6 is distributed only to communication device # 3.

  The association information included in the beacon signal of the communication device # 7 is received only by the communication device # 3, and the association information such as the address information and attribute information of the communication device # 7 is distributed only to the communication device # 3.

  As a result, each wireless communication device can receive a beacon signal of a wireless communication device existing in the vicinity, so in the autonomous distributed ad hoc network, the association information of each wireless communication device is notified by the beacon signal. The association process can be performed without any procedure.

  FIG. 4 schematically shows an internal configuration of a superframe managed for each communication station in the autonomous distributed network according to the present embodiment. Each communication station has its own super frame defined by beacon transmission, and a method of using the super frame will be described below.

  The superframe period (Superframe Duration) is defined by each communication station by its own beacon transmission (Beacon), and is managed as a further subdivided beacon relative position for each beacon relative position based on this beacon transmission timing. Done. In the illustrated example, one superframe is equally divided into 64, and 64 relative positions, that is, slots, 0 to 63, are provided.

  Here, at the head beacon relative position (position number: 0), a self-priority use area (TPP: Transmission Prioritized Period) is set following the transmission of the beacon.

  In this preferential use area TPP, the wireless communication apparatus is in an operating state, and message transmission from itself and reception of messages addressed to itself are performed.

  Further, a location other than the beacon relative position: 0 (position numbers 1 to 63) is set as a competitive access area (FAP) and is necessary between adjacent wireless communication apparatuses when there is a demand for communication. Depending on the use.

  Even in the area set as the preferential use area TPP, when predetermined communication is completed or communication is not performed, the preferential use area TPP is ended, and the adjacent wireless area is automatically set as the contention use area FAP. Used as necessary between communication devices.

  Alternatively, a configuration may be adopted in which a part of the competitive use area FAP is set as its own priority use area TPP and used preferentially for communication from a specific wireless communication device.

  FIG. 5 illustrates an operation for the communication station to start transmission in the TPP interval and the FAP interval configured at the timing after the beacon transmission of the local station.

  Within the TPP interval, the communication station can start transmission after a shorter frame interval SIFS (Short Inter Frame Space) after transmitting its own beacon. In the illustrated example, the beacon transmission station transmits an RTS packet after SIFS. After that, the transmitted CTS, data, and ACK packets are similarly transmitted in the interframe space of SIFS, so that a series of communication procedures can be executed without being disturbed by neighboring stations.

  On the other hand, in the FAP section, the beacon transmitting station also waits for a time period in which random backoff is added to the same frame interval LIFS (Long Inter Frame Space) as other peripheral stations, and then starts transmission. In other words, transmission rights are equally given to all communication stations by random backoff. However, LIFS is longer than SIFS. In the illustrated example, after the beacon of the other station is transmitted, the media state is first monitored by LIFS, and during this time, if the media is cleared, that is, if there is no transmission signal, random backoff is performed, and transmission is also performed during this period. When there is no signal, an RTS packet is transmitted. A series of packets such as CTS, data, ACK, etc. transmitted due to the RTS signal are transmitted in the inter-frame space of SIFS, so that they are not disturbed by neighboring stations and a series of communication procedures are preferentially executed. can do.

  According to the signal traffic management method described above, a communication station having a high priority (that is, using a priority use area) can preferentially acquire a transmission right by setting a shorter interframe space.

  However, the priority transmission period TPP is fixed to a fixed period equal to or less than the minimum beacon interval, and thereafter, the communication station called FAP shifts to a period in which a communication right is obtained under a common IFS and random backoff under equal conditions. . For this reason, when the communication station needs a communication band exceeding the preferential transmission period TPP obtained by one beacon transmission for each superframe due to a request from an upper layer, for example, an auxiliary other than a regular beacon A beacon can be transmitted and TPP can be acquired.

  FIG. 6 shows a state transition diagram of a wireless communication apparatus that operates as a communication station constituting an autonomous distributed network. In the illustrated example, an “operation waiting mode” waiting for a state in which this communication device should operate, a “beacon scan mode” that receives beacons from neighboring communication devices at a predetermined period, and an “association parameter” `` Deletion of association parameters '', `` Beacon transmission mode '' that transmits its own beacon, `` Data reception mode '' that receives data sent from neighboring communication devices, and neighboring communication devices Seven states of “data transmission mode” for transmitting data are defined.

  The communication station is in the sleep state as the normal operation waiting mode, and when the beacon scan cycle arrives, the communication station shifts to the beacon scan mode.

  Here, in the beacon scan mode, a beacon is received, an association parameter is described when a new beacon is received, and an association parameter is deleted when the existing beacon disappears.

  When the beacon scan cycle ends, the mode shifts to the operation waiting mode, but when the beacon scan cycle is within, the beacon scan operation is continued.

  When the local station beacon transmission time arrives, the communication station in the operation waiting mode performs beacon transmission describing its association parameters in the beacon transmission mode, and then once returns to the operation waiting mode. When the data reception time has arrived, the mode shifts to the data reception mode, the self-addressed data reception operation is performed for a predetermined time, and the operation standby mode is restored after the predetermined time is over.

  When the transmission data is accepted by the interface, the mode is changed to the data transmission mode, data transmission is performed according to the stored association parameter, and the operation waiting mode is returned after the transmission is completed.

  FIG. 7 shows an example of a state transition diagram as an access control method for a wireless communication apparatus operating as a communication station. In the illustrated example, “priority transmission mode” corresponding to the TPP period in which the local station has acquired the priority transmission right and “normal transmission mode” corresponding to the FAP period in which all communication stations have not obtained the priority transmission right. In addition, a state called “non-priority transmission mode” corresponding to the priority transmission period TPP of another station is defined.

  In the normal operation mode, the communication station waits for a period in which random backoff is added to the normal frame interval MIFS and then starts transmission. During the FAP period, all communication stations in the system transmit with MIFS + backoff

  Here, after the beacon transmission timing TBTT of the local station arrives and a beacon is transmitted, the mobile station transits to the priority transmission mode and acquires the priority transmission period TPP.

  Under the priority transmission mode, transmission right can be acquired without being disturbed by neighboring stations by performing transmission only in the waiting time of the frame interval SIFS shorter than MIFS. The communication station continues the priority transmission mode only for the priority transmission period TPP having a length corresponding to the bandwidth amount requested from the upper layer. When TPP ends and the process shifts to FAP, the normal transmission mode is restored.

  Further, when a beacon from another station is received and the priority transmission period of the other station is entered, a transition is made to the non-priority transmission mode. Under the non-priority transmission mode, transmission is started after waiting for a period in which random backoff is added to the frame interval LIFS longer than the frame interval MIFS in the normal transmission mode.

  When the TPP of the other station is completed and the process shifts to FAP, the normal transmission mode is restored.

  Returning to FIG. 4 again, the structure of the superframe will be described. In the wireless communication system according to the present embodiment, a predetermined beacon scanning period is defined, the presence or absence of a beacon signal from a surrounding wireless communication device is detected, and the existing wireless communication device disappears (moves from a directly communicable range). Or a new wireless communication device can be detected, that is, a scanning operation can be performed.

  In this scan operation, a continuous reception operation is performed in the contention use area FAP including the priority use area TPP over the super frame period (Scan Superframe Duration) to be scanned only once in a predetermined beacon scan period. A beacon signal of a wireless communication device existing around is received.

  In the autonomous decentralized network according to the present embodiment, each communication station prepares a beacon signal including an association parameter, notifies each superframe period, and receives a beacon signal from a peripheral station by a scanning operation or the like. . Thus, if a beacon signal can be received from a new wireless communication device in Scan Superframe Duration, an association process can be automatically performed with the wireless communication device.

  FIG. 8 schematically shows a functional configuration of the wireless communication apparatus 100 that operates as a communication station in the wireless network according to the embodiment of the present invention. In the same wireless system, the illustrated wireless communication apparatus 100 forms a network by managing autonomous network connection relationships according to the association and disassociation procedures according to the present invention, and effectively avoids collisions. Channel access can be performed.

  As illustrated, the wireless communication device 100 includes an interface 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, an antenna 109, and wireless reception. Unit 110, beacon analysis unit 112, information storage unit 113, and received signal analysis unit 114.

  The interface 101 exchanges various types of information with an external device (for example, a personal computer (not shown)) connected to the wireless communication apparatus 100.

  The data buffer 102 is used to temporarily store data sent from a device connected via the interface 101 and data received via the wireless transmission path before sending the data via the interface 101. The

  Central control unit 103 centrally performs a series of information transmission and reception processing management and transmission path access control in radio communication apparatus 100. In the present embodiment, basically, media access control based on CSMA or TDMA can be performed, and priority communication with other communication stations can be handled. In the access procedure based on CSMA, a backoff timer is operated over a random time while monitoring the state of the transmission path, and a transmission right is acquired when no transmission signal exists during this time.

  Further, in the present embodiment, the central control unit 103 autonomously performs procedures such as association and disassociation of the peripheral station based on the description content of the association message included in the beacon signal received from the peripheral station. Manages network connection relationships.

  The beacon generation unit 104 generates a beacon signal that the local station broadcasts every superframe. Also, the beacon analysis unit 112 analyzes a beacon signal that can be received from another station and a beacon signal.

  In the present embodiment, the beacon signal includes an association message including information necessary for managing the association state. The association message includes, for example, address information, capability information, attribute information, operation status, presence information of surrounding communication devices, and the like. By receiving the association message, it is possible to immediately grasp the operating state of surrounding communication stations. By analyzing the beacon, it is possible to acquire the neighboring device information including the beacon relative position and the association information, and the information is stored in the information storage unit 113.

  The wireless transmission unit 106 is a modulator that modulates a transmission signal with a predetermined modulation method such as OFDM (Orthogonal Frequency Division Multiplexing), a D / A converter that converts a digital transmission signal into an analog signal, and analog transmission Includes an up-converter that converts the frequency of the signal and up-converts, and a power amplifier (PA) that amplifies the power of the up-converted transmission signal (both not shown). Performs wireless signal transmission processing.

  The radio reception unit 110 includes a low noise amplifier (LNA) that amplifies a signal received from another station via the antenna 109, a down converter that downconverts the voltage amplified reception signal by frequency conversion, and an automatic gain controller ( AGC), an A / D converter that digitally converts an analog received signal, a synchronization process for acquiring synchronization, channel estimation, a demodulator that performs demodulation processing using a demodulation method such as OFDM, and the like (all not shown).

  The reception signal analysis unit 114 determines whether the user data to be processed is based on the information extracted by the wireless reception unit 110.

  The antenna 109 wirelessly transmits a signal addressed to another wireless communication device on a predetermined frequency channel, or collects a signal transmitted from the other wireless communication device. In this embodiment, it is assumed that a single antenna is provided and that transmission and reception cannot be performed in parallel.

  The timing control unit 107 controls timing for transmitting and receiving radio signals. For example, control of the transmission timing of each packet (RTS, CTS, data, ACK, etc.) according to its own packet transmission timing and RTS / CTS method (frame interval IFS from the previous packet reception until its own station transmits the packet) Timing setting such as setting of NAV (Network Association Vector) at the time of receiving a packet addressed to another station, transmission / reception of beacon, and the like.

  The information storage unit 113 stores an execution procedure instruction program such as a series of access control operations executed in the central control unit 103, information obtained from the analysis result of received packets and beacons, and the like. For example, information on neighboring devices and association information obtained by analyzing a beacon are stored in the information storage unit 113. This association information includes a neighboring communication device address, neighboring communication device operating status, neighboring communication device capability information, neighboring communication device attribute information, neighboring node presence information, preferential use area setting information, and the like.

  FIG. 9 shows a configuration example of a beacon frame used in the autonomous distributed network according to the present embodiment.

  This beacon signal is composed of common MAC header information, sub MAC header information, and a payload portion, and each portion is decoded as necessary on the receiving station side.

  The common MAC header information identifies the multiplexing number MUX of this frame, the receiving address Rx AD indicating the wireless communication device that needs to receive this frame (broadcast designation), and the wireless communication device that is the transmission source of this frame Source address Tx AD and a header check sequence HCS for detecting an error in this portion.

  Further, the sub MAC header information includes an identifier Type indicating that the format of this frame is a beacon, an information length Length of a payload portion having a variable length in this frame, an operating status indicating the operating status of the wireless communication device, and The header check sequence HCS for detecting an error in this portion.

  Further, as the data payload portion of the beacon frame, capability information indicating the operation capability of the wireless communication device, attribute information indicating the attribute of the wireless communication device, and other wireless communication devices in the vicinity of the wireless communication device Neighboring Node presence information indicating presence / absence of presence / absence, and additional setting as necessary, preferential use Area setting indicating a preferential use area in the wireless communication apparatus, and frame check sequence FCS for detecting an error in the payload portion Consists of.

  In this embodiment, each wireless communication device uses an autonomous decentralized association table to manage association parameters included in beacon signals received from neighboring wireless communication devices based on its own beacon transmission position. To manage. FIG. 10 shows a configuration example of this association table.

  In this table, one entry is provided for each time lot configured by dividing the superframe period into 1/64, and the wireless communication apparatus can be accommodated at a timing corresponding to each entry.

Each entry of the association parameter table stores a communication device address, a communication device operating status, communication device capability information, communication device attribute information, neighboring node presence information, preferential use area setting information, etc. along with the beacon relative position Field is available.

  The 0th entry in the association parameter table corresponds to the transmission beacon of the own station, and stores the association parameter transmitted from the own station to the surrounding stations.

  Each time a beacon signal is received in the superframe, the latest state is managed in an entry based on the beacon transmission position of the local station.

  An entry corresponding to an area where no beacon signal is received is managed as an unused area. In this case, it may be set as its own preferential use area as necessary at the time of data transmission or the like.

  FIG. 11 shows the procedure of the association operation performed by each communication station in the form of a flowchart in the autonomous distributed network according to the present embodiment. This operation procedure is actually realized in a form in which the central control unit 103 executes a predetermined execution command program in the wireless communication apparatus 100 operating as a communication station in the autonomous distributed network according to the present embodiment. .

  First, when power is supplied to the wireless communication device (step S1), its own address information is set (step S2), and its own capability information and attribute information are set (step S3).

  And the reception scanning operation | movement of the beacon signal from a neighborhood radio | wireless communication apparatus is performed (step S4). If the beacon information is received (step S6) before the end of the scanning period (step S5), the wireless communication device address of the corresponding beacon is acquired (step S7). If the transmission source of the received beacon is a newly appearing wireless communication device, the address of the corresponding wireless communication device is acquired (step S8) and described in the above-described association parameter table (step S9).

  Further, even if the source of the received beacon is other than the new wireless communication device, information from neighboring wireless communication devices is collected in response to the reception of the beacon (step S10), and the association parameter table stores the information of the communication device. The operating status, the neighboring node presence status, and the capability / attribute information of the communication device are recorded (steps S11 to S13).

  And the radio | wireless communication apparatus used as the transmission source of the received beacon is set as self neighbor Node presence information (step S14).

  Further, a preferential use area of the wireless communication device that is the transmission source of the received beacon is set (step S15).

  Thereafter, in order to continue the predetermined beacon receiving operation, the process returns to step S5, and the reception is continued until the end of the scanning period.

  Further, even if the beacon cannot be received in step S6, the process returns to step S5 to continue the predetermined beacon receiving operation, and the reception is continued until the end of the scan period.

  Further, if it is determined in step S5 that the scan period has ended, the next beacon scan cycle is set (step S16).

  Here, it is checked whether or not there is a wireless communication apparatus that has become unable to receive a beacon for a predetermined time (step S17). If there is a wireless communication device that can no longer receive a beacon, it is determined that the wireless communication device has disappeared, and the association information of the wireless communication device is deleted from the association parameter table (step S18).

  When the beacon transmission timing of the own station has arrived (step S19), the operation status of the own wireless communication device is set (step S20), and the own beacon signal is wirelessly transmitted (step S21).

  If the set beacon scan period has arrived (step S22), the process returns to step S4 to detect the beacon signal from the neighboring wireless communication device again, and perform the association parameter update operation.

  When it is necessary to transmit data from the device connected by the interface 101 to another device (step S23), the transmission information related to the corresponding destination communication station is stored in the association parameter table. It is confirmed whether it is registered as a communication device (step S24). If registered, the operating status of the wireless communication device is grasped based on the corresponding entry of the association parameter (step S25). When the timing at which transmission to the transmission destination becomes possible (step S26), data transmission is performed (step S27), and if necessary, the operation status of itself is changed (step S28).

  On the other hand, when the reception timing at the local station has arrived (step S29), the wireless reception unit 110 is operated to perform an information reception operation (step S30). When data addressed to itself is received (step S31), the data is output to a device connected via the interface 101 (step S32), and the operation status of the device is changed if necessary. (Step S33).

  Thereafter, in order to perform a beacon scan, the process returns to step S22 and a series of operations are repeated. Alternatively, if it is determined in step S29 that it is not the reception timing, the process returns to step S22 in the same manner.

  Here, if the self-addressed data is not received in the determination in step S31, the process returns to step S29 again, and the reception operation is repeated over the period of the reception timing.

  If it is determined in step S23 that the data has not been received, or if it is determined in step S24 that the transmission request is not addressed to an existing communication device, the process returns to the confirmation of the timing of the transmission beacon in step S19. The series of processing is repeated.

  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 in which the present invention is applied when a communication station performs association and disassociation in an autonomous distributed wireless network has been mainly described. In addition, the present invention can be similarly applied to easily manage the network connection relationship.

  The present invention can also be applied to media access control in each channel even for a multi-channel communication system in which each communication station performs communication by hopping on a plurality of frequency channels.

  Further, in the present specification, the embodiment of the present invention has been described by taking a wireless LAN as an example. However, the gist of the present invention is not limited to this, and an ultra-wide band that performs signal transmission / reception in a lower SNR environment. The present invention can be preferably applied to a communication system such as (Ultra Wide Band).

  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 section described at the beginning should be considered.

FIG. 1 is a diagram schematically showing a configuration of an autonomous distributed network according to a position embodiment of the present invention. FIG. 2 is a diagram for explaining a procedure in which each communication station performs beacon transmission within a superframe. FIG. 3 is a diagram illustrating a state in which a beacon signal is exchanged between wireless communication devices forming a network and an association operation is performed. FIG. 4 is a diagram illustrating the internal configuration of the superframe managed by the wireless communication apparatus. FIG. 5 is a diagram for explaining an operation for the communication station to start transmission in each of the TPP section and the FAP section. FIG. 6 is a diagram illustrating a state transition diagram of a wireless communication apparatus that operates as a communication station. FIG. 7 is a diagram showing a state transition diagram as an access control method for a wireless communication apparatus operating as a communication station. FIG. 8 is a diagram schematically illustrating a functional configuration of a wireless communication apparatus that operates as a communication station in the wireless network according to the embodiment of the present invention. FIG. 9 is a diagram illustrating a configuration example of a beacon frame. FIG. 10 is a diagram showing a configuration example of the association table. FIG. 11 is a flowchart showing the procedure of the association operation performed by the communication station.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Wireless communication apparatus 101 ... Interface 102 ... Data buffer 103 ... Central control part 104 ... Beacon generation part 106 ... Wireless transmission part 107 ... Timing control part 109 ... Antenna 110 ... Wireless reception part 112 ... Beacon analysis part 113 ... Information storage 114: Received signal analyzer

Claims (12)

A wireless communication system in which each communication station performs network operation in an autonomous and distributed manner without arranging a specific control station,
Each communication station broadcasts an association message at a predetermined cycle, and receives the broadcasted association message to detect the state of the communication station existing in the vicinity, and configures an autonomous distributed network To figure out,
A wireless communication system. The communication station has at least one of address information uniquely assigned to the own station, capability information indicating the device capability or device attribute of the own station, operation mode information indicating the operation status of the own station, and information on peripheral stations. In the association message,
The wireless communication system according to claim 1. The communication station manages the association message received from the peripheral station as the association state of the peripheral station.
The wireless communication system according to claim 1. Manage the association status including communication stations that are unable to join or authenticate in the process of association or authentication processing depending on higher layers and applications,
The wireless communication system according to claim 3. The communication station cancels the association status of the peripheral station that is no longer able to receive the association message.
The wireless communication system according to claim 3. A wireless communication device that performs data transmission in a wireless communication environment in which a specific control station is not disposed,
A communication means for transmitting and receiving wireless data over a channel;
An association message generating means for generating an association message describing information about the own station;
An association message analyzing means for analyzing an association message received from a peripheral station by the communication means;
Network connection relation management means for detecting the state of communication stations existing in the vicinity based on the analysis result of the association message and grasping the communication stations constituting the autonomous distributed network;
A wireless communication apparatus comprising: The association message generating means includes address information uniquely assigned to the own station, capability information indicating the device capability or device attribute of the own station, operation mode information indicating the operation status of the own station, and information on peripheral stations. Include at least one of them in the association message,
The wireless communication apparatus according to claim 6. The network connection relation management means manages an association message received from a peripheral station as an association state of the peripheral station.
The wireless communication apparatus according to claim 6. The network connection relation management means manages an association state including a communication station that cannot be joined or authenticated in the course of an association or authentication process depending on an upper layer or an application.
The wireless communication apparatus according to claim 8. The network connection relation management means cancels the association state of the peripheral station that has become unable to receive an association message.
The wireless communication apparatus according to claim 8. A wireless communication method for performing data transmission in a wireless communication environment in which no specific control station is arranged,
An association message sending step for sending an association message describing information about the own station;
An association message receiving step for receiving and analyzing an association message from a peripheral station;
A network connection relation management step for detecting the state of communication stations existing in the vicinity based on the analysis result of the association message and grasping the communication stations constituting the autonomous distributed network;
A wireless communication method comprising: A computer program written in a computer-readable format so as to execute processing for performing data transmission on a computer system in a wireless communication environment in which a specific control station is not arranged,
An association message sending step for sending an association message describing information about the own station;
An association message receiving step for receiving and analyzing an association message from a peripheral station;
A network connection relation management step for detecting the state of communication stations existing in the vicinity based on the analysis result of the association message and grasping the communication stations constituting the autonomous distributed network;
A computer program comprising:

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