JP4112241B2 - Communication system and communication method - Google Patents

Communication system and communication method Download PDF

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Publication number
JP4112241B2
JP4112241B2 JP2002046844A JP2002046844A JP4112241B2 JP 4112241 B2 JP4112241 B2 JP 4112241B2 JP 2002046844 A JP2002046844 A JP 2002046844A JP 2002046844 A JP2002046844 A JP 2002046844A JP 4112241 B2 JP4112241 B2 JP 4112241B2
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Japan
Prior art keywords
access point
communication
wireless terminal
channel
belonging
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JP2003249939A (en
Inventor
幸政 永井
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三菱電機株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication system including a plurality of wireless terminals and an access point having a data relay function, and in particular, supports an infrastructure mode and an ad hoc mode as operation modes, and selects an operation mode. The present invention relates to a communication system and a communication method for performing communication between terminals.
[0002]
[Prior art]
Hereinafter, a conventional communication method will be described. When a plurality of movable wireless terminals are connected to an access point (wireless station) having a data relay function, each wireless terminal is connected by sharing a band of one channel provided by the access point. .
[0003]
In addition, when each wireless terminal performs data communication such as Web browsing via an access point, it may be a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) method that may cause contention during data transmission, or A polling system that avoids contention during data transmission by centrally managing transmission timing by an access point is used. In particular, in the IEEE802.11 system, both CSMA / CA and polling systems are defined.
[0004]
In addition, when each wireless terminal starts up in an infrastructure mode in which the access point controls transmission of the wireless terminal, for example, when exchanging data such as FTP, Telnet, chat, etc., via the access point or by the access point Communication is performed using the arbitrated polling period.
[0005]
In addition, when wireless terminals operating in infrastructure mode connect in ad hoc mode (equal distributed network communication method) that controls transmission between wireless terminals, it is necessary to switch the driver on the wireless terminal side and restart There is. In the ad hoc mode, since communication is performed between wireless terminals, data communication via an access point is not possible.
[0006]
[Problems to be solved by the invention]
However, in the above-described conventional communication method, for example, when a wireless terminal receives a service in the infrastructure mode, when communication is performed between wireless terminals under the same access point, Communication using the polling period arbitrated by the access point will occur. Therefore, there is a problem that other wireless terminals provided with services from the access point cannot secure a sufficient band due to communication traffic between the wireless terminals.
[0007]
Conversely, when performing communication between wireless terminals in ad hoc mode, there is no access point, so there is no connection to the wired network as the backbone, and there is a problem that the Internet cannot be used such as Web browsing. .
[0008]
The present invention has been made in view of the above. For example, even when communication is performed between wireless terminals in the infrastructure mode, other wireless terminals provided with services from the access point are not sufficient. An object of the present invention is to obtain a communication system and a communication method that can secure a sufficient band.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, the communication system according to the present invention includes an access point having a data relay function and a plurality of wireless terminals belonging to the access point, and an infrastructure. The wireless terminals operating in the mode and the access point perform communication using the first communication channel at a reception interval of a predetermined broadcast signal intermittently transmitted by the access point, and further to the access point Wireless terminals operating in the infrastructure mode to which they belong use the second communication channel other than the first communication channel while maintaining the first communication channel provided by the access point. The terminal-to-terminal communication in the ad hoc mode is performed during the idle time in the reception interval.
[0010]
In the communication system according to the next invention, a wireless terminal operating in the infrastructure mode performs carrier sense of a plurality of communication channels, and an empty channel obtained from the carrier sense result is assigned to the second communication channel. It is characterized by.
[0011]
In the communication system according to the next invention, the access point checks a packet between wireless terminals belonging to itself during communication in the infrastructure mode, and at least one of the wireless terminals is set as the same access point. The inter-terminal communication is promoted by notifying that it belongs.
[0012]
In the communication system according to the next invention, the first access point which is the access point is connected to the second access point on the network, and the wireless terminal belonging to the second access point is connected to the first access point. When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point in a state where service can be received from the access point, the wireless terminal belonging to the second access point is A handover is executed, the current communication channel is switched to the first communication channel provided by the first access point, and the inter-terminal communication is performed under the control of the first access point. .
[0013]
In the communication system according to the next invention, the first access point as the access point is connected to the second access point on the network, and the wireless terminal belonging to the first access point is connected to the second access point. When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point in a state where service can be received from the access point, the wireless terminal belonging to the first access point is A handover is executed, the first communication channel is switched to a communication channel provided by a second access point, and the inter-terminal communication is performed under the control of the second access point.
[0014]
In the communication system according to the next invention, in the inter-terminal communication in the ad hoc mode, the wireless terminal requesting the inter-terminal communication becomes a temporary access point, and the wireless terminal of the communication partner is set during the period of operation in the ad hoc mode. It is characterized by management.
[0015]
In the communication method according to the next invention, in a communication system including an access point having a data relay function and a plurality of wireless terminals belonging to the access point, the wireless terminals operating in the infrastructure mode and the wireless terminal The access point is operating in a first communication step of performing communication using the first communication channel at a reception interval of a predetermined broadcast signal intermittently transmitted by the access point, and in an infrastructure mode belonging to the access point The wireless terminals use the second communication channel other than the first communication channel while maintaining the first communication channel provided by the access point to provide free time in the reception interval. And a second communication step for performing inter-terminal communication in ad hoc mode. And features.
[0016]
In the communication method according to the next invention, in the second communication step, the wireless terminal operating in the infrastructure mode performs carrier sense of a plurality of communication channels, and the free channel obtained from the carrier sense result The second communication channel is used.
[0017]
In the communication method according to the next invention, in the second communication step, the access point checks packets between wireless terminals belonging to itself in communication in the infrastructure mode, and for at least one of the wireless terminals The inter-terminal communication is promoted by notifying that the mobile station belongs to the same access point.
[0018]
In the communication method according to the next invention, the first access point as the access point is connected to the second access point on the network, and the wireless terminal belonging to the second access point is connected to the first access point. When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point in a state where service can be received from the access point, the wireless terminal belonging to the second access point is A handover is executed, the current communication channel is switched to the first communication channel provided by the first access point, and the inter-terminal communication is performed under the control of the first access point. .
[0019]
In the communication method according to the next invention, the first access point which is the access point is connected to the second access point on the network, and the wireless terminal belonging to the first access point is connected to the second access point. When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point in a state where service can be received from the access point, the wireless terminal belonging to the first access point is A handover is executed, the first communication channel is switched to a communication channel provided by a second access point, and the inter-terminal communication is performed under the control of the second access point.
[0020]
In the communication method according to the next invention, in the inter-terminal communication in the ad hoc mode, the wireless terminal requesting inter-terminal communication becomes a temporary access point, and the wireless terminal of the communication partner is set during the period of operation in the ad hoc mode. It is characterized by management.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a communication system and a communication method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
[0022]
Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a communication system according to a first embodiment of the present invention. In FIG. 1, 1 and 2 are access points (AP) that can operate in the infrastructure mode, and 3, 4 and 5 are wireless terminals belonging to the access point 1. Each AP is connected by a wired network.
[0023]
FIG. 2 is a diagram showing the configuration of the APs 1 and 2, wherein 10 is an upper layer, 11 is an upper layer protocol processing unit, 20 is a data link layer, and 21 is a channel access unit. , 22 is a beacon generation processing unit, 23 is a resource allocation processing unit, 24 is a virtual carrier sense unit, 25 is a timer, 26 is a time counter, 30 is a physical layer, 31 is A modulation / demodulation processing unit.
[0024]
Each AP includes a physical layer 30, a data link layer 20, and an upper layer 10. In the data link layer 20, frame transmission corresponding to a communication method such as CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) and polling is performed. A channel access unit 21 that performs control is provided. Further, the channel access unit 21 of each AP is based on a beacon generation processing unit 22 that transmits a beacon signal at regular intervals, a resource allocation processing unit 23 for reserving frequency resources, and information in the received frame. When a NAV (Net Allocation Vector) is set and it is determined that the communication channel is busy, the virtual carrier sense 24 is set so that the transmission control of the own terminal is not performed while the other terminal is using the channel. Prepare.
[0025]
FIG. 3 is a diagram showing the configuration of the wireless terminals 3, 4, and 5. 40 is an upper layer, 41 is an upper layer protocol processing unit, 50 is a data link layer, and 51 is a channel. An access unit, 52 is a beacon generation processing unit, 53 is a resource allocation processing unit, 54 is a virtual carrier sense unit, 55 is a timer, 56 is a time counter, and 57 is a beacon analysis process. 58 is a resource request processing unit, 60 is a physical layer, and 61 is a modulation / demodulation processing unit.
[0026]
Each wireless terminal includes a physical layer 60, a data link layer 50, and an upper layer 40. In the data link layer 50, a frame corresponding to a communication method such as CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) or polling. A channel access unit 51 that performs transmission control is provided. The channel access unit 51 of each wireless terminal includes a beacon generation processing unit 52, a resource allocation processing unit 53, and a virtual carrier sense unit 54 similar to the beacon generation processing unit 22, the resource allocation processing unit 23, and the virtual carrier sense unit 24. In addition, a beacon analysis processing unit 57 for analyzing time synchronization and channel configuration based on a beacon signal transmitted by the AP, and a resource request processing unit 58 for performing channel reservation are provided.
[0027]
Here, the communication method of the present embodiment in the communication system will be described in detail. FIG. 4 is a diagram illustrating a communication method according to the present embodiment. A signal drawn by a black rectangular wave and a white rectangular wave on the time axis of AP1 represents a notification signal periodically transmitted from the AP, that is, a beacon frame (Beacon). Further, for convenience of explanation, the black beacon frame represents a case where communication is performed between the AP 1 and the wireless terminal 3 or the wireless terminal 4, and the white beacon frame is hereinafter referred to as AP 1 and the wireless terminal 3 or the wireless terminal 4. This represents the case where communication is not performed with the.
[0028]
AP1 broadcasts allocation information including a channel configuration, transmission timing, transmission time, and terminal address through a beacon frame. By receiving this beacon frame, each wireless terminal establishes time synchronization and simultaneously grasps the channel configuration. In AP1, a beacon frame is transmitted as a periodic signal. However, if carrier sense of the channel is executed before the transmission of the beacon frame and the medium is busy as a result, the transmission of the beacon frame is idle. Postponed until. The signal P represents a packet transmitted by the AP 1 or each wireless terminal.
[0029]
Between AP1 and each wireless terminal, a plurality of packet exchanges are performed at beacon frame intervals (beacon intervals). For example, in the beacon interval from Beacon (1) to Beacon (2), the wireless terminal 3 first transmits a packet to AP1, then the wireless terminal 5 transmits a packet to AP1, and finally, AP1 wirelessly transmits. A packet is transmitted to the terminal 4. Note that such packet transmission / reception may be performed using either the polling method controlled by AP1 or the CSMA / CA method adjusted by AP1.
[0030]
In the beacon interval from Beacon (2) to Beacon (3), packet exchange is not performed between AP1 and wireless terminal 3 or wireless terminal 4, as shown. That is, in this beacon interval, the wireless terminal that communicates with AP1 is only the wireless terminal 5, and communication between the wireless terminal 5 and AP1 is normally performed using a channel provided by AP1.
[0031]
In addition, in the beacon interval from Beacon (2) to Beacon (3), in addition to the communication between the wireless terminal 5 and the AP 1, communication between terminals between the wireless terminal 3 and the wireless terminal 4 by the ad hoc mode ( Adhoc (1)). FIG. 5 is a diagram illustrating inter-terminal communication (Adhoc (1)) between the wireless terminal 3 and the wireless terminal 4. Inter-terminal communication indicated by Adhoc (1) is performed using a second channel different from the channel on which AP1 provides a service. This Adhoc (1) ends before the time when the next Beacon (3) is transmitted, and thereafter, the wireless terminal 3 and the wireless terminal 4 perform carrier sense of the channel used by the AP1, and are transmitted from the AP1. Next Beacon (3) is received and the next beacon interval allocation status is ascertained.
[0032]
Here, the determination method and setting method of the second channel in Adhoc (1) will be described. FIG. 6 is a diagram illustrating a determination method and a setting method of the second channel in Adhoc (1). The following procedure is performed while the wireless terminal 3 and the wireless terminal 4 are operating in the infrastructure mode before receiving Beacon (2). Further, the packet exchange sequence between wireless terminals here may be a polling method under the control of AP1, or a CSMA / CA method in which AP1 has arbitrated.
[0033]
First, in the wireless terminal 3, the “ad hoc” including the address, ID (Identifier), BSSID (Basic Service Set Identifier), ESSID (Extended Service Set Identifier) which is an ID of the integrated network, etc. A mode request packet is transmitted, and carrier sense is performed using a time when there is no communication with the access point AP1 in order to search for an empty channel.
[0034]
The wireless terminal 4 that has received the “ad hoc mode request packet” determines whether it can operate in the ad hoc mode by comparing with its own terminal address, ID, BSSID, ESSID, and the like. If possible, the wireless terminal 4 performs carrier sense using the time when there is no communication with the access point AP1 for searching for an empty channel, and includes the address, ID, BSSID, ESSID, etc. of its own terminal. An “ad hoc mode permission / rejection packet” is transmitted, and an “empty channel packet” including the result of carrier sense is transmitted.
[0035]
The wireless terminal 3 that has received the “ad hoc mode permission / rejection packet” and the “empty channel packet” can operate in the ad hoc mode in the wireless terminal 4, and the result of carrier sense by the wireless terminal 3 and the wireless terminal 4. If there is a free channel that can be used, that channel is determined as the second communication channel. Then, a “use channel inquiry packet” is transmitted to the wireless terminal 4.
[0036]
In the wireless terminal 4 that has received the “used channel inquiry packet”, the channel included in the packet is set as the second channel used in the ad hoc mode. Then, a “used channel confirmation packet” indicating that the setting has been completed is transmitted to the wireless terminal 3, and thereafter, it becomes operable in the ad hoc mode.
[0037]
The wireless terminal 3 that has received the “used channel confirmation packet” is operable in the ad hoc mode, similarly to the wireless terminal 4. For convenience of explanation, a procedure of inter-terminal communication (Adhoc) will be described using the radio terminal 3 and the radio terminal 4, but inter-terminal communication is similarly performed between other terminals.
[0038]
Next, even in the beacon interval from Beacon (3) to Beacon (4), packet exchange is not performed between AP1 and wireless terminal 3 or wireless terminal 4, similarly to the previous beacon interval. Here, the wireless terminal 3 and the wireless terminal 4 perform inter-terminal communication (Adhoc (2)), and end Adhoc (2) before receiving Beacon (4). Then, the wireless terminal 3 and the wireless terminal 4 perform carrier sense of the channel used by the AP 1 in the infrastructure mode in order to receive Beacon (4). Further, communication between the wireless terminal 5 and AP1 is performed as usual using a channel provided by the AP1.
[0039]
In the beacon interval from Beacon (4) to Beacon (5), Beacon (4) includes contents for transmitting and receiving packets between AP1, wireless terminal 3, wireless terminal 4, and wireless terminal 5. So it works in infrastructure mode. In addition, when the operation in the ad hoc mode using the second channel is not performed for a certain period, the “ad hoc mode request packet” is transmitted again when the inter-terminal communication is performed, and a new second channel is searched.
[0040]
As described above, in the present embodiment, when there is no communication with the AP, the inter-terminal communication is performed using the second channel other than the channel for which the AP provides the service. Thereby, since communication between terminals via the AP can be avoided, it is possible to sufficiently secure a band of a channel for which the AP provides a service. In addition, when it is necessary to perform communication from the AP to the wireless terminal, the inter-terminal communication is temporarily stopped.
[0041]
In addition, Web browsing, which is communication via an access point, can be performed as usual. Further, inter-terminal communication can be realized without changing the setting of the wireless terminal, that is, without restarting the wireless terminal.
[0042]
In addition, although this Embodiment demonstrated the form which communicates by a CSMA / CA system or a polling system, it is not restricted to this, Communication between AP and a radio | wireless terminal is a TDMA (Time Division Multiple Access) system. Even if it is performed, it can be similarly applied. In this case, the beacon from the AP is replaced with a BCH (Broadcast Channel) broadcast in the downlink direction and an FCH (Frame Channel) composed of frame information broadcast in the downlink direction. Each wireless terminal interprets the frame configuration by receiving the BCH and the FCH, and performs communication between terminals using the second channel when it is determined that there is no communication within the period. At this time, the inter-terminal communication performed on the second channel may be any of CSMA / CA, polling, and TDMA.
[0043]
Embodiment 2. FIG.
FIG. 7 is a diagram showing the configuration of the second embodiment of the communication system according to the present invention. In FIG. 7, reference numeral 7 denotes a wireless terminal. Note that the configurations of the AP and the wireless terminal are the same as those in FIGS. 2 and 3 described above.
[0044]
In the present embodiment, a case will be described in which the wireless terminal 3 performs inter-terminal communication with the wireless terminal 7 in a state where the wireless terminal 7 belonging to AP2 can receive services from a plurality of APs (AP1 and AP2).
[0045]
Since AP1 and AP2 use different channels, synchronization of beacon frames transmitted periodically is not established between APs. Therefore, communication between terminals cannot be performed using the communication method of the first embodiment as it is. Therefore, in the present embodiment, the wireless terminal 7 that is in a state where it can receive services from a plurality of access points switches the AP that receives service provision from handover from AP2 to AP1, and performs inter-terminal communication in the state after switching. .
[0046]
FIG. 8 is a diagram illustrating a communication method according to the second embodiment. First, the wireless terminal 3 transmits an “ad hoc mode request packet” including its own address, ID, ESSID, and the like to the wireless terminal 7 and does not communicate with the AP 1 for searching for a free channel. Use your time to make a career sense.
[0047]
The wireless terminal 7 that has received the “ad hoc mode request packet” recognizes that it is connected to the AP 2 different from the wireless terminal 3 by comparing with its own address, ID, BSSID, ESSID, etc. Sense (reception sensitivity, etc.) for the channel providing the data to determine whether or not handover is possible. For example, when a handover is possible, the wireless terminal 7 performs carrier sense using a time when there is no communication with the AP 2 in order to search for an empty channel for performing communication between terminals. If there is an empty channel and the operation in the ad hoc mode is possible, the receiving terminal 7 executes the handover and switches the communication channel with the current AP 2 to the communication channel of the AP 1. An “ad hoc mode permission / rejection packet” including an address, ID, BSSID, ESSID, and the like is transmitted, and an “empty channel packet” including a carrier sense result is transmitted.
[0048]
The wireless terminal 3 that has received the “ad hoc mode permission / rejection packet” and the “empty channel packet” can operate in the ad hoc mode in the wireless terminal 7, and the result of carrier sense by the wireless terminal 3 and the wireless terminal 7. If there is a free channel that can be used, that channel is determined as the second communication channel. Then, a “use channel inquiry packet” is transmitted to the wireless terminal 7.
[0049]
In the wireless terminal 7 that has received the “used channel inquiry packet”, the channel included in the packet is set as the second channel used in the ad hoc mode, and the “used channel confirmation packet” indicating the end of the setting is set to the wireless terminal 3. After that, it is ready to operate in ad hoc mode.
[0050]
The wireless terminal 3 that has received the “used channel confirmation packet” is operable in the ad hoc mode, similarly to the wireless terminal 7.
[0051]
As described above, in the present embodiment, when wireless terminals receiving services from different APs perform inter-terminal communication, handover is performed so that one wireless terminal can receive the services provided from the same AP. The communication channel is switched by executing, and the same inter-terminal communication as that of the first embodiment is performed in a state where the communication channel belongs to the same AP. Thereby, since communication between terminals via the AP can be avoided, it is possible to sufficiently secure a band of a channel for which the AP provides a service.
[0052]
In addition, Web browsing, which is communication via an access point, can be performed as usual. Further, inter-terminal communication can be realized without changing the setting of the wireless terminal, that is, without restarting the wireless terminal.
[0053]
Embodiment 3 FIG.
In the third embodiment, when the wireless terminal 7 that has transmitted the “ad hoc mode request packet” is in a state where service can be received from another AP to which the wireless terminal 3 that is the communication partner belongs, the requesting wireless terminal 7 To switch the current communication channel to the communication channel of the AP to which the wireless terminal of the communication partner belongs. Note that the configuration of the communication system is the same as that in FIG. 7 described above, and therefore the same reference numerals are given and description thereof is omitted. Here, the wireless terminal 7 transmits an “ad hoc mode request packet” on the assumption that the wireless terminal 7 belonging to the AP 2 can receive services from a plurality of APs (AP 1 and AP 2).
[0054]
FIG. 9 is a diagram illustrating a communication method according to the third embodiment. First, the wireless terminal 7 transmits an “ad hoc mode request packet” including its own address, ID, BSSID, ESSID, etc. to the wireless terminal 3 and communicates with the AP 2 to search for a free channel. Use the time when there is no career sense.
[0055]
In the wireless terminal 3 that has received the “ad hoc mode request packet”, the wireless terminal 3 is connected to an AP 1 different from the AP 2 to which the wireless terminal 7 is connected, as compared with the address, ID, BSSID, ESSID, and the like of the local terminal. Recognize that Then, in order to search for a channel for performing communication between terminals, carrier sense is performed using a time when there is no communication with AP1. When there is an empty channel, a “handover request message”, an “ad hoc mode permission / rejection packet”, and an “empty channel packet” are transmitted to the wireless terminal 7.
[0056]
The wireless terminal 7 that has received the “handover request message”, “ad hoc mode permission / rejection packet”, and “empty channel packet” can perform handover to the communication channel of the access point 1 and can be performed by the wireless terminal 3 and the wireless terminal 7. If there is an available empty channel from the carrier sense result, that channel is determined as the second communication channel. Then, handover is executed to switch the current communication channel to the communication channel of AP 1, and a “used channel inquiry packet” is transmitted to the wireless terminal 3.
[0057]
In the wireless terminal 3 that has received the “used channel inquiry packet”, the channel included in the packet is set as the second channel to be used in the ad hoc mode, and the “used channel confirmation packet” indicating the end of setting is set to the wireless terminal 7. After that, it is ready to operate in ad hoc mode.
[0058]
The wireless terminal 7 that has received the “used channel confirmation packet” becomes operable in the ad hoc mode, similarly to the wireless terminal 3.
[0059]
As described above, in the present embodiment, when wireless terminals receiving services from different APs perform inter-terminal communication, handover is performed so that one wireless terminal can receive the services provided from the same AP. The communication channel is switched by executing, and the same inter-terminal communication as that in the first embodiment is performed in a state where the communication channel belongs to the same AP. Thereby, since communication between terminals via the AP can be avoided, it is possible to sufficiently secure a band of a channel for which the AP provides a service.
[0060]
In addition, Web browsing, which is communication via an access point, can be performed as usual. Further, inter-terminal communication can be realized without changing the setting of the wireless terminal, that is, without restarting the wireless terminal.
[0061]
Embodiment 4 FIG.
FIG. 10 is a diagram illustrating a communication method according to the fourth embodiment. In the fourth embodiment, the AP 1 checks a packet transmitted from the wireless terminal 3 to the wireless terminal 4 and prompts one of the wireless terminals for inter-terminal communication. The configuration of the communication system is the same as that of FIG.
[0062]
FIG. 11 is a diagram showing a configuration of an address field defined by IEEE802.11MAC, and FIG. 12 is a diagram showing a setting method of an address field at the time of packet transmission in an infrastructure network. In the frame format defined in IEEE802.11MAC, ToDS (To Distribution System), FromDS (From Distribution System), Add1 (Address 1), Add2 (Address 2), Add3 (Address 3), and Add4 (Address 4) Communication is to be performed using the address field. Here, DS (Distribution System) represents a system for bridging a BSS (Basic Service Set), which is a basic network of a wireless LAN, and a LAN (Local Area Network). In addition, ToDS is ToDS = 1 when transmission is directed to DS, ToDS = 0 when transmission is not directed to DS, and FromDS is set to FromDS = 1 when transmitted from DS. If it is an internal communication that does not go through, FromDS = 0. Here, the structure of the address field stipulates that communication is always performed via an AP even between wireless terminals belonging to the same AP.
[0063]
Therefore, in AP1, for example, wireless terminal 3 and wireless terminal 4 belong to their own by comparing the list of wireless terminals connected to itself with the destination field of the packet transmitted by the wireless terminal of the transmission source. It is possible to know that communication between terminals is about to start.
[0064]
Here, the communication method of the present embodiment will be described with reference to FIG. First, the wireless terminal 3 transmits a packet to the wireless terminal 4 via AP1. At this time, the address field of IEEE802.11 MAC includes ToDS = 1, FromDS = 0, Add1 = AP1 address (connection point), Add2 = wireless terminal 3 address (source), Add3 = wireless terminal 4 address (transmission) First). However, the address of the wireless terminal 3 is STA1, and the address of the wireless terminal 4 is STA2.
[0065]
The AP 1 that has received the packet from the wireless terminal 3 refers to the connection list held by itself and recognizes that the wireless terminal 4 that is the packet transmission destination belongs to itself. If the wireless terminal 4 is not a wireless terminal belonging to AP1, the packet is transferred to another AP (such as an access point via the DS).
[0066]
Next, in AP1, the address field of IEEE802.11MAC is ToDS = 0, FromDS = 1, Add1 = address of wireless terminal 4 (destination), Add2 = address of AP1 (connection point), Add3 = address of wireless terminal 3 Set to (Sender) and send the packet.
[0067]
Upon receiving the response packet transmitted from the wireless terminal 4 to the wireless terminal 3, AP1 transfers the packet to the wireless terminal 3 and transmits an inter-terminal communication request packet.
[0068]
Then, in the wireless terminal 3 that has received the inter-terminal communication request packet, inter-terminal communication is realized by the communication method of the first embodiment described above. In the case where one wireless terminal is in a state where service can be received from another AP to which the other wireless terminal as a communication partner belongs as in the second or third embodiment described above, the embodiment Inter-terminal communication is realized by two or three communication methods.
[0069]
As described above, in the present embodiment, the AP checks the packet between the wireless terminals and prompts one of the wireless terminals to communicate with the terminal. Thereby, the same effects as those of the first to third embodiments can be obtained.
[0070]
Embodiment 5. FIG.
FIG. 13 is a diagram illustrating a communication method according to the fifth embodiment. In the fifth embodiment, the inter-terminal communication (Adhoc (1) (2)) in the first embodiment will be described in detail. Here, the wireless terminal 3 that has transmitted the “ad hoc mode request packet” becomes a temporary AP in the inter-terminal communication period, and controls transmission of the wireless terminal 4 that is the communication partner. Here, Adhoc (1) will be described for convenience of explanation.
[0071]
In the wireless terminal 3, when inter-terminal communication (Adhoc (1)) is started, Beacon (21) for informing allocation information including channel configuration, transmission timing, transmission time, and terminal address is changed to Adhoc (1 ) On the second communication channel used. Thereby, between the wireless terminal 3 and the wireless terminal 4 which became temporary AP, a transmission timing etc. are determined and it can communicate between terminals in a beacon interval.
[0072]
【The invention's effect】
As described above, according to the present invention, when there is no communication with an access point, inter-terminal communication is performed using the second communication channel other than the communication channel through which the access point provides a service. Thereby, since communication between terminals via an access point can be avoided, there is an effect that it is possible to obtain a communication system capable of sufficiently securing a communication channel band used in the infrastructure mode.
[0073]
According to the next invention, since the wireless terminal operating in the infrastructure mode performs a carrier sense and searches for an empty channel, a communication system capable of easily detecting the second communication channel is obtained. There is an effect that can be.
[0074]
According to the next invention, the access point checks the packet between the wireless terminals, and prompts at least one of the wireless terminals for inter-terminal communication. Thereby, there is an effect that a communication system capable of efficiently avoiding communication between terminals via an access point can be obtained.
[0075]
According to the next invention, when wireless terminals receiving services from different access points perform inter-terminal communication, handover is performed so that one wireless terminal can receive services from the same access point. Thus, the communication channel is switched and communication between terminals is performed while belonging to the same access point. Thereby, since communication between terminals via an access point can be avoided, there is an effect that it is possible to obtain a communication system capable of sufficiently securing a communication channel band used in the infrastructure mode.
[0076]
According to the next invention, when wireless terminals receiving services from different access points perform inter-terminal communication, handover is performed so that one wireless terminal can receive services from the same access point. Thus, the communication channel is switched and communication between terminals is performed while belonging to the same access point. Thereby, since communication between terminals via an access point can be avoided, there is an effect that it is possible to obtain a communication system capable of sufficiently securing a communication channel band used in the infrastructure mode.
[0077]
According to the next invention, the configuration is such that the transmission timing and the like with the wireless terminal serving as the communication partner are determined by the management of the wireless terminal serving as the temporary access point. Thereby, there is an effect that it is possible to obtain a communication system capable of easily realizing communication between terminals at the reception interval of the notification signal.
[0078]
According to the next invention, when there is no communication with the access point, the communication between terminals is performed using the second communication channel other than the communication channel for providing the service by the access point. Thereby, since communication between terminals via an access point can be avoided, the bandwidth of the communication channel used in the infrastructure mode can be sufficiently secured. Further, there is an effect that communication between terminals can be realized without changing the setting of the wireless terminal, that is, without restarting the wireless terminal.
[0079]
According to the next invention, since the wireless terminal operating in the infrastructure mode performs carrier sense and searches for a free channel, the second communication channel can be easily detected.
[0080]
According to the next invention, the access point checks the packet between the wireless terminals and prompts at least one of the wireless terminals to perform the communication between terminals. As a result, there is an effect that communication between terminals via the access point can be efficiently avoided.
[0081]
According to the next invention, when wireless terminals receiving services from different access points perform inter-terminal communication, handover is performed so that one wireless terminal can receive services from the same access point. Then, the communication channel is switched, and communication between terminals is performed while belonging to the same access point. Thereby, since communication between terminals via an access point can be avoided, the bandwidth of the communication channel used in the infrastructure mode can be sufficiently secured.
[0082]
According to the next invention, when wireless terminals receiving services from different access points perform inter-terminal communication, handover is performed so that one wireless terminal can receive services from the same access point. Then, the communication channel is switched, and communication between terminals is performed while belonging to the same access point. Thereby, since communication between terminals via an access point can be avoided, the bandwidth of the communication channel used in the infrastructure mode can be sufficiently secured.
[0083]
According to the next invention, the transmission timing and the like with the wireless terminal serving as the communication partner are determined by the management of the wireless terminal serving as the temporary access point. Thereby, there is an effect that communication between terminals can be easily realized at the reception interval of the notification signal.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a first embodiment of a communication system according to the present invention.
FIG. 2 is a diagram showing a configuration of an access point.
FIG. 3 is a diagram illustrating a configuration of a wireless terminal.
4 is a diagram illustrating a communication method according to Embodiment 1. FIG.
FIG. 5 is a diagram illustrating terminal-to-terminal communication (Adhoc (1)).
FIG. 6 is a diagram illustrating a method for determining and setting a second channel in Adhoc (1).
FIG. 7 is a diagram showing a configuration of a communication system according to a second embodiment of the present invention.
8 is a diagram illustrating a communication method according to Embodiment 2. FIG.
9 is a diagram illustrating a communication method according to Embodiment 3. FIG.
10 is a diagram illustrating a communication method according to the fourth embodiment. FIG.
FIG. 11 is a diagram showing a configuration of an address field defined by IEEE802.11MAC.
FIG. 12 is a diagram showing a method for setting an address field at the time of packet transmission in an infrastructure network.
13 is a diagram illustrating a communication method according to the fifth embodiment. FIG.
[Explanation of symbols]
1, 2 Access point (AP), 3, 4, 5, 7 Wireless terminal.

Claims (12)

  1. An access point having a data relay function, and a plurality of wireless terminals belonging to the access point, and each wireless terminal operating in the infrastructure mode and the access point are transmitted by the access point intermittently. In a communication system that performs communication using the first communication channel at a notification signal reception interval,
    The wireless terminals operating in the infrastructure mode belonging to the access point maintain the first communication channel provided by the access point , and the wireless terminals exchange packets between the wireless terminals. In the sequence, using the time when there is no communication with the access point , search for a free channel other than the first communication channel , respectively , and when there is a free channel that can be used based on both search results, A communication characterized in that an empty channel is determined as a second communication channel to be used in the ad hoc mode, and inter-terminal communication in the ad hoc mode is performed during the empty time in the reception interval using the second communication channel. system.
  2. The first as a process of searching a free channel other than the communication channel, the communication system according to claim 1, characterized in that intends to carrier sense line.
  3. The access point checks packets between wireless terminals belonging to itself communicating in infrastructure mode, and notifies the terminal that at least one of the wireless terminals belongs to the same access point. The communication system according to claim 1, wherein intercommunication is promoted.
  4. In a state where the first access point which is the access point is connected to the second access point on the network, and the wireless terminal belonging to the second access point can receive service from the first access point,
    When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point,
    A wireless terminal belonging to the second access point executes handover, switches the current communication channel to the first communication channel provided by the first access point, and is subordinate to the first access point. The communication system according to claim 1, wherein the communication between the terminals is performed.
  5. In a state where the first access point which is the access point is connected to a second access point on the network, and a wireless terminal belonging to the first access point can receive service from the second access point,
    When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point,
    A wireless terminal belonging to the first access point executes a handover, switches the first communication channel to a communication channel provided by a second access point, and is subordinate to the second access point. The communication system according to claim 1 or 2, wherein communication between terminals is performed.
  6. The inter-terminal communication in the ad hoc mode is characterized in that a wireless terminal requesting inter-terminal communication serves as a temporary access point, and manages a wireless terminal as a communication partner during a period of operation in the ad hoc mode. The communication system according to any one of 1 to 5.
  7. In a communication method in a communication system including an access point having a data relay function and a plurality of wireless terminals belonging to the access point,
    A first communication step in which each wireless terminal operating in the infrastructure mode and the access point perform communication using a first communication channel at a reception interval of a predetermined notification signal that the access point transmits intermittently. When,
    The wireless terminals operating in the infrastructure mode belonging to the access point maintain the first communication channel provided by the access point , and the wireless terminals exchange packets between the wireless terminals. In the sequence, using the time when there is no communication with the access point , search for a free channel other than the first communication channel , respectively , and when there is a free channel that can be used based on both search results, A second communication step of determining an empty channel as a second communication channel to be used in the ad hoc mode, and performing inter-terminal communication in the ad hoc mode during the empty time in the reception interval using the second communication channel; ,
    A communication method comprising:
  8. Wherein a first processing for searching a free channel other than the communication channel The communication method according to claim 7, characterized in that intends to carrier sense line.
  9. In the second communication step,
    The access point checks packets between wireless terminals belonging to itself communicating in infrastructure mode, and notifies the terminal that at least one of the wireless terminals belongs to the same access point. The communication method according to claim 7 or 8, wherein intercommunication is promoted.
  10. In a state where the first access point which is the access point is connected to the second access point on the network, and the wireless terminal belonging to the second access point can receive service from the first access point,
    When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point,
    A wireless terminal belonging to the second access point executes handover, switches the current communication channel to the first communication channel provided by the first access point, and is subordinate to the first access point. The communication method according to claim 7 or 8, wherein inter-terminal communication is performed.
  11. In a state where the first access point which is the access point is connected to a second access point on the network, and a wireless terminal belonging to the first access point can receive service from the second access point,
    When a wireless terminal belonging to the first access point communicates with a wireless terminal belonging to the second access point,
    A wireless terminal belonging to the first access point executes a handover, switches the first communication channel to a communication channel provided by a second access point, and is subordinate to the second access point. The communication method according to claim 7 or 8, wherein communication between terminals is performed.
  12. The inter-terminal communication in the ad hoc mode is characterized in that a wireless terminal requesting inter-terminal communication serves as a temporary access point, and manages a wireless terminal as a communication partner during a period of operation in the ad hoc mode. The communication method according to any one of 7 to 11.
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