JP2003333053A - Autonomously formed wireless lan system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily form a network by easily setting access points and gateways. <P>SOLUTION: This system has, as constituents, a plurality of access points AP1-AP4 and gateways GW1-GW3 for providing access means with the Internet 43. Radio links are autonomously formed between access points AP1-AP4, and between the access points AP1-AP4 and the gateways GW1-GW3. A packet communication between mobiles MS1-MS3, or between the mobiles MS1-MS3 and the gateways GW1-GW3 is conducted via a single or a plurality of access points AP1-AP4 and the radio link. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous formation type wireless LAN system suitable for constructing and operating a next generation information communication network using a wireless LAN such as a voluntary network.

[0002]

2. Description of the Related Art In parallel with the development of the Internet, the market of wireless LAN (WLAN) is expanding rapidly. WL
AN is more promising than a mobile phone in terms of constant connectivity and high-speed data communication, and has a weaker electric field strength than a mobile phone. For example, AN can be used without problems in the medical field. It is expected that introduction will progress more rapidly and a comfortable information communication environment will be established. But when you leave these offices and homes,
Since WLANs cannot be used and rely on mobile phones to make a difference in the information communication environment, it is ideal to enjoy the same comfortable information communication environment anytime anywhere. That is,
If a seamless advanced information and communication environment is realized, it will have a significant ripple effect on the economy and society.
The debate on mobile communications for generations is intensifying.

On the other hand, in recent years, as the number of users of wireless terminals has increased, it has been desired to diversify and enhance new applications and services. Along with that, wireless LAN
Various products related to (1) have become widely used in offices and homes due to cost reduction and communication speed improvement.

[0004]

As is well known, the wireless LAN according to the above-mentioned prior art has an access point (hereinafter referred to as an AP) that enables communication with a wireless terminal installed in an appropriate place in an office or home. An indoor network is formed by connecting the APs with a wired or wireless link, and there is no need to draw a LAN cable between the wireless terminal and the AP, so that organizations and individuals can freely use wireless. Although it has the advantage that an environment can be constructed and operated, it has the following problems.

That is, when considering the outdoor use,
In addition to having to consider the location of APs, in the form of wired connection between APs with an Ethernet (registered trademark) cable or the like, there is complexity in cable wiring, and a great deal of labor and cost must be spent for network construction. I have to.
It also makes it difficult to move or move APs freely.

[0006] Therefore, an object of the present invention is to provide an autonomous formation type wireless LAN system in which an access point and a gateway can be easily installed and a network can be easily formed without considering the location and wiring. And

[0007]

According to a first aspect of the present invention, an autonomous formation type wireless LAN system has a plurality of access points and a gateway for providing an access means for the Internet as a constituent element. A wireless link is autonomously formed between the access point and the gateway, and packet communication between wireless terminals or between a wireless terminal and the gateway is performed via one or a plurality of the access points and the wireless link. is there.

In this case, if an access point or gateway is installed at an appropriate place, a wireless link is autonomously established with respect to the installed access point or gateway, and this wireless link and one or a plurality of access points are established. Multi-hop packet communication via the network becomes possible.

In the autonomous formation type wireless LAN system according to claim 2, each access point has a first wireless device which communicates with the wireless terminal and a second wireless device which communicates with another access point. ing.

As described above, each access point is separately provided with the first wireless device provided for communication with the wireless terminal and the second wireless device provided for communication with another access point. ing. Therefore, the first wireless device can be designed to communicate with existing wireless terminals while the second wireless device is designed to perform multi-hop packet communication.

According to another aspect of the present invention, in the autonomous formation type wireless LAN system, packet communication between the wireless terminals or between the wireless terminal and the gateway is performed, and transfer between the wireless terminal and the access point on a transmitting / receiving side is performed. The transfer is performed separately from transfer from the access point at the start point to the access point at the end point.

In this case, the packet transferred from the wireless terminal on the transmitting side to the access point is rewrapped (encapsulated) at this access point. And
At the access point to which the wireless terminal on the receiving side belongs, a packet is extracted from the encapsulated one and then sent out to the wireless terminal on the receiving side. That is, when the network is viewed from the wireless terminal side, it is merely transmitting and receiving normal packets, and the network can be utilized without being aware of the communication method between access points.

According to another aspect of the present invention, the autonomous formation type wireless LAN system automatically establishes a route from the access point at the start point to the access point at the end point in packet transfer between the access points.

In this case, not between the transmitting and receiving wireless terminals,
A route (routing) from the start point to the end point of the access point is automatically established, and the packet can be transferred along this route.

In the autonomous formation type wireless LAN system according to claim 5, the wireless terminal or the access point is fixedly or movably provided, and the address information of the wireless terminals belonging to the access point is transmitted and received between the access points. By doing so, each access point recognizes the wireless terminal belonging to itself and other access points.

As a result, regardless of whether or not the wireless terminal or the access point moves, each access point can obtain the address information of not only the wireless terminal to which it belongs but also the wireless terminals belonging to all other access points. I can figure it out. Therefore, each access point can specify the destination of the received packet based on the address information.

In the autonomous forming type wireless LAN system according to the sixth aspect, the address information of the wireless terminal belonging to each access point is transmitted and received together with the route information transmitted and received between the access points.

In this case, each access point can send and receive address information to and from each other, and can also send and receive route information at the same time. Therefore, the destination and the route of the received packet can be specified based on the address information and the route information regardless of whether the wireless terminal or the access point moves.

According to a seventh aspect of the present invention, in the autonomous formation type wireless LAN system, each access point exchanges information about a channel number used when each access point performs packet communication with the wireless terminal to which the access point belongs. To decide.

As a result, the channel (frequency) number for communicating with the access point to which the wireless terminal belongs is autonomously and decentralized by information exchange between the access points. Therefore, channel numbers can be assigned so as not to cause interference between adjacent access points.

In the autonomous formation type wireless LAN system in claim 8, the communication procedure between the wireless terminal and the access points belonging to it is the same as the conventional wireless LAN system, and the communication between the access points from the start point to the end point. The procedure is hidden from the wireless terminal.

In this case, when the network is viewed from the wireless terminal side, the communication method between the access points is hidden, so that the wireless terminal does not care about the communication method between the access points and the wireless terminal performs the same communication procedure as before. With this method, communication with an access point can be performed.

In the autonomous formation type wireless LAN system in claim 9, the access point to which the wireless terminal belongs is transferred to another access point, and the data packet to the wireless terminal belongs to the original It has an inter-access point communication procedure for transferring a data packet arriving at the original access point to the current access point when delivered to the access point.

With this configuration, even if the access points to which the wireless terminals belong change from one to another, since the wireless links are autonomously formed between the access points, the communication procedure between the access points is The data packet is transferred from this access point to the current access point via the wireless link, and the data packet can be correctly transferred to the wireless terminal.

An autonomous formation type wireless LAN according to claim 10
In the method, when the gateway has a plurality of configurations, one gateway issues an IP address request to another gateway to detect the presence or absence of another gateway,
If another gateway exists, it knows the network identifier from its IP address and responds to IP address requests from the access point and the wireless terminal.

In this case, when an IP address request is issued from one gateway to another gateway, the dynamically assigned IP address is returned to the original gateway as long as another gateway exists. As a result, the gateway that has received the response can know the IP address and the network identifier included therein. Also, when an IP address request is received from any wireless terminal or access point, the gateway can dynamically assign an IP address in response to the inquired wireless terminal or access point.

An autonomously forming wireless LAN according to claim 11
The method is such that the access point seeking an IP address broadcasts an IP address server discovery packet, and the gateway that receives it responds,
An IP address is acquired by sending an IP address request packet to one of the discovered gateways.

In this way, even if there are a plurality of gateways that have responded to the IP address server discovery packet, the access point seeking the IP address sends the IP address request packet to only one of the gateways, so that the wireless link with that gateway is established. Being established autonomously,
It can receive a single IP address.

An autonomous formation type wireless LAN according to claim 12.
In the method, the gateway or the access point periodically discovers an IP address server, updates the number of hops with a plurality of gateways, etc., and selects a gateway through which to connect to the Internet.

In this case, the gateway or access point periodically discovers the IP address server and updates the number of hops with a plurality of gateways. Therefore, when a wireless terminal accesses the Internet,
You can choose the best gateway.

The autonomously forming wireless LAN according to claim 13
In the method, when the access point receives a response to the IP address server discovery from a plurality of gateways, the plurality of gateways are recorded.

This allows each access point to know the existence of a plurality of gateways that have received the response.

An autonomous formation type wireless LAN according to claim 14
According to the method, the access point uses the IP from the wireless terminal.
When an address server is found and an IP address request is received, it is IP-encapsulated, transferred to the selected gateway, and an IP address is given.

In this case, upon receiving the IP address server discovery and IP address request from the wireless terminal, the access point to which it belongs transfers the IP encapsulated IP address server discovery and IP address request to the selected gateway. As a result, the wireless terminal autonomously establishes a wireless link with the selected gateway and can independently receive the IP address from the selected gateway.

An autonomously forming wireless LAN according to claim 15
The method is such that when the wireless terminal makes an address resolution request,
The access point receiving it transfers it to all the gateways and the access points, the gateway transfers it to the router connected to the Internet, the access point transfers it to all the wireless terminals to which it belongs, and from the plurality of routers. When there is a response via each gateway, the response via the already selected gateway is selected and returned to the wireless terminal.

When a wireless terminal makes an address resolution request, the address resolution request is transferred to all wireless terminals, gateways, routers, and access points, but a response is sent from a plurality of routers via the respective gateways. If so, it is possible to select a response via the gateway that has already been selected and return the physical address corresponding to the destination IP address to the wireless terminal.

An autonomous formation type wireless LAN according to claim 16.
According to the method, when the gateway receives an IP packet addressed to the wireless terminal from the Internet, it transfers the packet from itself via the wireless LAN system or detours it to another gateway and enters the wireless LAN system from there. , The wireless LAN system configuration information stored in itself and the wireless terminal information belonging to each access point.

In this case, when the gateway receives an IP packet addressed to the wireless terminal from the Internet, the gateway transfers the packet from itself via the wireless LAN system or diverts it to another gateway, and then the wireless LAN is transmitted from there.
The gateway can immediately determine whether to enter the system.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an autonomous formation type wireless LAN device according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a wireless multihop LAN (WM) proposed in common with each embodiment.
FIG. 4 shows a preferred configuration diagram of a device called LAN). In the figure, AP1 to AP4 are fixed or movable access points, MS1 to MS3 are portable and movable wireless terminals, that is, mobile terminals, and these access points are within the radio wave reach of each access point AP1 to AP4. Information can be exchanged via AP1 to AP4. Mobile terminals MS1 to MS3
And the access points AP1 to AP4 move, so that, for example, the mobile terminal MS3 becomes one access point A.
The affiliation may be changed from P3 to another access point AP4. This is called roaming. In this case, this embodiment has an inter-access point communication procedure for transferring a data packet arriving at the original access point AP3 to the current access point AP4. The access points AP1 to AP4 and mobile terminals MS1 to MS3
Is not limited to the number in the embodiment.

In this embodiment, the access points AP1 to AP1
From the viewpoint of enabling relocation or movement of the AP 4, the access points AP1 to AP4 are connected by a wireless link.
Specifically, wireless LAN access points AP1 to AP1
For example, P4 may be installed by an individual at the doorstep of his / her home, installed by a local government along a street, installed by a bus company along a stop, or installed in a moving body such as a taxi or private car. For example, the access point AP at the starting point
1 and the access point AP4 at the end point are separated from each other, and when the packet cannot be transferred from the access point AP1 to the AP4 in one hop, the other access points AP2 and AP3 on the way are used for relay, and the access point at the end point in the multihop The packet is transferred to AP4. This form is particularly applicable to wireless multi-hop LAN (WMLA).
N) and access points AP1 to AP4 used in the wireless multi-hop LAN are called multi-hop access points.

On the other hand, the mobile MS1 to MS3 are terminals used in a normal wireless LAN (WLAN) and do not require any special function. That is, in the above example, mobile M
The communication procedure between the S1 and the access point AP1 and between the access point AP4 and the mobile MS3 is the same as that of the conventional WLAN, and the communication procedure between the start point access point AP1 and the end point access point AP4 is , The mobile MS1 and MS3 are hidden. As a result, the existing terminal can be directly incorporated into the wireless multi-hop LAN.

In the wireless multi-hop LAN, a mobile ad hoc network (MANET) is used for connection between the access points AP1 to AP4. The mobile ad-hoc network itself is a network in which mobile terminals directly exchange information wirelessly without an access point (Journal of the Institute of Electronics, Information and Communication Engineers Vol84 No.2 pp.127).
~ 134 (see February 2001)). In this mobile ad hoc network, mobile terminals are self-distributed on an equal basis with each other, without relying on base stations, which were indispensable elements in the construction of conventional mobile communication networks, or wire networks connecting base stations. The behavior of mobile terminals that cannot perform direct exchange of information due to radio wave reception is provided with the function of exchanging information by relaying mobile terminals on the way. This is characterized in that it is used for connection between access points AP1 to AP4 and between gateways GW1 to GW3 and access points AP1 to AP4 described later, not between mobile terminals.

Then, each access point AP1 to AP
4 functions as a WLAN access point, while communication between the access points AP1 to AP4 is performed by the MA.
This is done using the wireless multi-hop function of NET. That is, each of the access points AP1 to AP4
WL for communicating with mobile MS1 to MS3
It has two wireless interfaces consisting of a first wireless device 11 for providing an AN service and a second wireless device 12 for performing wireless multi-pop communication of MANET with other access points AP1 to AP4.

FIG. 2 is a schematic explanatory diagram showing the software architecture (structure) of the WMLAN. As mentioned above, in WMLAN, WLAN layer 21 and MANET
There are two layers, layer 22. Each of the access points AP1 to AP4 functions as a device that bridges these layers. This WLAN layer 21 and MANE
As specific architectures for bridging with the T layer 22, examples of LAN emulation and IP-IP encapsulation will be specifically described below.

FIG. 3 illustrates a protocol layer structure of LAN emulation supported by the WLAN layer 21. Here, consider an example in which a packet is transferred in multiple hops from a mobile terminal MS1 of a basic service set (BSS) subordinate to the access point AP1 to a mobile terminal MS3 of a different BSS subordinate to the access point AP3.

The mobile terminals MS1 and MS3 each have a protocol hierarchical structure of IEEE80 which constitutes a data link layer.
2.11 compliant physical layer 31 and MAC (Media Access C
ontrol: media access control layer 32, and TCP / IP layer 33 that is a network and transport layer,
The application layer 34 for providing an actual service to the user.

When the mobile terminal MS1 transmits a frame associated (attached) to the starting point access point AP1, the starting point access point AP1 that has received the frame determines whether the frame should be transmitted within its own area. Determine whether or not. Each of the access points AP1 to AP3 has an individual access point AP1 to AP3.
IP address of AP4 and mobile terminal M subordinate to it
It manages a list of physical addresses of S1 to MS3 and also transfers the mobile terminal MS2 of the transfer destination to the frame.
Is included in the physical address, that is, the MAC address, and the access point AP1 makes the above determination by collating both addresses.

Then, if the frame is to be transmitted within its own area, the access point AP1 transfers the frame to the terminal matching the physical address, and if not, the routing function of the MANET layer 22 is used. Mobile terminal MS to send frame using
2 retrieves the IP address of the associated access point AP3. If the access point AP1 knows the end point access point AP3,
The frame is delivered to the LAN emulator of MLAN21 (see LANE of reference numeral 36 in FIG. 3). The LANE 36 has a function of encapsulating the received frame as it is in an IP datagram. At this time, the IP address of the destination access point AP3 discovered by the routing function is given to the destination IP address. When the frame is encapsulated in IP by the LANE 36 in this way, it is delivered from the WLAN layer 21 to the MANET layer 22.

The IP packet delivered to the MANET layer 22 is transferred to the target access point AP3 while performing wireless multi-hop based on the MANET routing protocol. When the target access point AP3 receives the IP packet, the access point AP3 extracts and restores the frame encapsulated in the packet, and based on the WLAN layer 21, the frame is transmitted to the mobile terminal MS2 subordinate to its own area. To send.

Thus, all mobile MS1 to MS3
Is provided with a conventional WLAN layer 21 based interface. WLAN layer 21 here is ESS
It is configured as (Extended Service Set) and is WMLA from the viewpoint of mobile MS1 to MS3.
It looks as if all N are forming one physical network. Further, the LANE 36 causes the frame to be encapsulated as IP data. Therefore, M
Since the ANET layer 22 only relays the frame as data, it does not care about the existence of the MANET layer 22 in the WLAN. That is, the MANET layer 22 here only provides LAN emulation to the WLAN layer 21, and the mobiles MS1 to MS3 can be used without noticing the MANET layer 22.

FIG. 4 shows W based on IP-IP encapsulation.
3 illustrates a protocol hierarchical structure of MLAN.
Here again, consider an example in which a packet is transferred in multiple hops from the mobile terminal MS1 subordinate to the access point AP1 to the mobile terminal MS3 subordinate to the access point AP3.

The WLAN layer 21 is constructed as a group of several BSSs, and one BSS constitutes one physical network. In addition, TCP in FIG.
Instead of the / IP layer 33, here, the TCP / UDP layer 37, which is a single transport layer of the protocol layer structure, and the IP layer 38, which is the network layer, are described separately.

It is assumed that the mobile terminal MS1 of one BSS sends a frame to the mobile terminal MS2 belonging to another BSS. The mobile terminal MS1 uses the same BS as the mobile terminal MS1 as the default (initial setting) route.
The access point AP1 of S is selected. The IP packet received by the starting access point AP1 is IP-encapsulated by the access point AP1 and transferred to the target access point AP3 while performing wireless multi-hop. And the access point AP at the end point
When the access point AP3 receives the IP packet, the access point AP3 extracts and restores the frame encapsulated in the packet, and sends the IP packet to the destination mobile terminal MS2 subordinate to its own area.

Here, in order to support the movement of the mobile terminals MS1 to MS3 during communication, the IP addresses of the mobile terminals MS1 to MS3 are prevented from changing due to movement. Start point access point AP1
Needs to figure out the IP address of the access point AP3 at the end point corresponding to the IP address which is the network address of the mobile terminal MS2 of the transfer destination. To this end, each access point AP1 to AP3 manages a list of IP addresses of the individual access points AP1 to AP4 and the mobile terminals MS1 to MS3 subordinate thereto.

As described above, in the WMLAN, the individual access points AP1 to AP4 are mobile terminals MS1.
~ While providing normal WLAN service to MS3, MANET between access points AP1 to AP4
Connected by wireless multi-pop communication by. Therefore, the size of the network constructed by the WMLAN can be easily changed by adding or removing the access points AP1 to AP4.

In the above configuration, an example in which each of the access points AP1 to AP4 has two wireless interfaces has been described. However, actually, there may be a case where each of the WLAN side and the MANET side has a plurality of wireless interfaces. . In that case, in the example of LAN emulation, multiple physical addresses are given to the WLAN side, and M
A plurality of physical addresses and IP addresses will be given to the ANET side.

By the way, in the existing WLAN compliant with the standard such as IEEE802.11, it is possible to perform communication by using a plurality of channels. AP
The problem that 4 interferes occurs. Therefore, when the transmission ranges of the neighboring access points AP1 to AP4 overlap, the number of channel numbers needs to be separated by a certain amount or more. Further, in the WLAN, frequent transfer and movement of the access points AP1 to AP4 are expected, so that the interference zone also changes each time the topology changes, which makes it difficult to perform fixed channel allocation by design. That is, it becomes important at what timing and how to perform channel allocation.

That is, access points AP1 to AP
Assuming that a WLAN of IEEE802.11b is used as the wireless interface of 4, in that case, a channel (frequency) divided into 14 can be used in the frequency of 2.4 GHz band. However, for example, access point A
When the channel No. 5, that is, ch5, is assigned to P1, ch4 and ch6 whose frequencies are close to each other are used in the vicinity of, for example, the access point A when communicating with the mobile terminal MS1.
When assigned to P2, interference occurs between the access points AP1 and AP2.

Therefore, in the above-mentioned WMLAN, fixed or moving access points AP1 to AP4
However, a specific method of autonomously allocating a channel in consideration of the access points AP1 to AP4 that are close to each other will be described below.

In the WLAN adopted in this embodiment, since the access points AP1 to AP4 are connected by the mobile ad hoc network (MANET), only one channel is used for communication between the access points AP1 to AP4. Therefore, access point A
For example, when ch1 is assigned to the communication between P1 to AP4, the other channels ch2 to ch14 are assigned to the access points AP1 to AP4.

For example, when ch1 is assigned to MANET,
The WLAN can allocate up to four channels of ch5, ch8, ch11, and ch14 in the same area, and can be used without worrying about interference. Further, in the access points AP1 to AP4 spatially separated (for example, the access points AP1 and AP4 in FIG. 1), if the channels are reused in the respective access points AP1 to AP4, a small number of channels can be efficiently used. .

By the way, in the WMLAN, since it is difficult to set a fixed channel in advance, it is necessary to have a function of allocating channels in an autonomous distributed manner. In order to prevent the same channel from being assigned to neighboring access points AP1 to AP4,
In the T layer 22, channel allocating means that does not allocate the same channel is introduced to m hop adjacent access points. The m-hop adjacent access points referred to here are all the access points AP1 to AP within m hops.
It is defined as P4. Each access point AP1-A
In P4, the channel number assigned to the m-hop adjacent access point is the used channel, and the other channels are idle channels. Therefore, each access point A
The channel allocating means of P1 to AP4 has a function of selecting a specific channel from idle channels and allocating it when communicating with the subordinate mobile terminals MS1 to MS3.

In the WMLAN, each access point AP1 to AP4 has two layers, a WLAN layer 21 and a MANET layer 22. Considering some patterns based on the magnitude of the communication distance in each layer, the optimal number of hops m in each of these patterns
You can decide. Here, each access point AP
1 to AP4, the communication distance of WLAN is LW, and M
If the communication distance of ANET is LM, two patterns as shown in FIGS. 5 and 6 are conceivable.

In the pattern shown in FIG. 5, the communication distance LM of MANET is smaller than twice the communication distance LW of WLAN (LM <LW), and the coverage areas of the access points AP1 and AP2 (the mobile terminal is Since the access point and the communicable area) overlap, it is necessary to allocate different channels to the access points AP1 and AP2. If access point AP
1 If there is another access point between AP2, 2
The access points AP1 and AP2 can be connected by popping. Therefore, by setting the number of hops m = 2, different channels are assigned to the access points AP1 and AP2. However, access points AP1, AP2
There is no other access point in between, access point A
When P1 and AP2 are connected with 3 pops or more,
If the number of hops is m = 2, the access points AP1, A
The same channel may be assigned at P2. Therefore, by selecting a large number of hops m, the possibility of interference can be reduced, but in this case, the possibility of channel reuse is reduced.

In the pattern shown in FIG. 6, the communication distance LM of MANET is more than twice the communication distance LW of WLAN (LM ≧
LW), and if the number of hops is m = 1 in this case, the coverage areas of the access point AP1 and the access point AP2 do not overlap with each other, and interference can be reduced. As described above, in the WMLAN, the possibility of interference can be reduced by setting the communication distance LM of MANET to be twice or more the communication distance LW of WLAN.

As described above, the present embodiment is characterized in that the network on the MANET side is used to know information such as the number of hops m and the channels are assigned to the access points AP1 to AP4 in an autonomous distributed manner. Instead of the information on the number of hops, the position information of each of the access points AP1 to AP4 obtained from the position detecting means such as GPS may be used to perform the optimum channel allocation.

Next, the procedure (algorithm) of actual channel allocation will be described. First, as a precondition, the number of available channels is n, and each access point AP1 to AP1
A unique ID (identifier) is assigned to P4.

This algorithm is divided into two phases, ID exchange and channel allocation. In the ID exchange, in MANET between the access points AP1 to AP4, each access point AP1 to AP4 periodically sets the ID of its own access point AP1 to AP4 by m / 2 (rounded up) to m / 2 (rounded up). It transmits to all of the access points AP1 to AP4 that are adjacent to the hop. Thereby, each access point AP1 to AP
4 is access points AP1 to AP adjacent to m hops
You can know all 4 IDs.

The next channel allocation consists of the following five stages.

The access points AP1 to AP4 are m
The access points AP1 to AP4 which are adjacent to the hop and which are not allocated to the channels are compared with their own IDs, and their own I
When D is smaller than all IDs, proceed to step.

M-hop adjacent access point AP
1-AP4 is used to refer to the used channels, and its own channel is selected from free channels. If there are no free channels, then no channels are assigned.

This assigned channel is assigned to access points AP1 to AP4 that are m hops adjacent to each other in MANET.
Tell. The access points AP1 to AP4, which have no free channels and cannot be assigned channels, have access points AP1 to AP4 having IDs larger than their own IDs.
So as to allocate a channel to each access point AP1 to AP4.

In each of the access points AP1 to AP4, the access points AP1 to AP4 adjacent by m hops
Record the channel assigned to as the used channel.

When the topology changes due to the movement or relocation of the access points AP1 to AP4, re-channel allocation is performed.

As a result, each of the access points AP1 to AP1
Channels are assigned to AP4 in an autonomous distributed manner.

Further, another channel allocation procedure (algorithm) will be described. First, each access point AP
Clustering is performed for 1 to AP4, and channels are assigned to cluster heads. That is, the access points AP1 to AP4 are generated by the clustering algorithm.
Cluster. A cluster head is set for each cluster, and the cluster head and the access points AP1 to AP4 in the cluster are connected by one hop. Here, access points that belong to a plurality of clusters are called GWs (gateways). Each cluster head notifies its own ID to the cluster head of another cluster via the GW. As a result, the cluster head of each cluster is
Know the ID of the cluster head (there may be a plurality of cluster heads, which is called an adjacent cluster head) that shares

If the ID of its own cluster head is smaller than the IDs of all adjacent cluster heads to which no channels are assigned, its own channel is arbitrarily determined from among the empty channels. Then, the assigned channel is transmitted to all nodes (access points AP1 to AP4) two hops away. Each access point AP1 to AP4 stores a channel assigned to a node within two hops.
If there is no free channel, no channel is assigned.

After that, channels are assigned also to the access points AP1 to AP4 other than the cluster head. In that case, if the self ID is not assigned and is smaller than the IDs of all the access points AP1 to AP4 that are adjacent by two hops, an arbitrary channel is assigned from the empty channels. On the contrary, if there is no free channel, no channel is assigned.

Next, the moving access points AP1 to AP1
Control of routing for the AP 4 and mobile terminals MS1 to MS3 will be described.

The movement of the access points AP1 to AP4 is managed by using the routing protocol operating in the MANET layer 22, and the mobile terminals MS1 to MS3 are controlled.
Is managed in the WLAN layer 21. MAN
The routing protocol used in the ET layer is
There are table-driven type, on-demand type, and hybrid type that combines these, and these are all W
Although an MLAN configuration is possible, a table drive type operation will be described here as an example.

Normally, the table driven routing protocol owns the link state table of all nodes. First, a node transmits a hello packet and at the same time receives a hello packet from another node, thereby discovering a node adjacent to itself. Since the communication between the nodes here is performed on the same frequency (channel), it is possible to easily find the adjacent node by using the hello packet for exchanging information between the adjacent nodes. . Next, the state of the adjacent node of itself is flooded (transmitted to all nodes other than the node that received it) to transmit to all the nodes. By performing this operation by all the nodes, each node can know the link status of all the nodes in the network and can find the route to the target node.

If this routing protocol is applied to the MANET layer 22 between the access points AP1 to AP4, the procedure will be as follows. For example, the access point AP1 first transmits a hello packet to the adjacent node (for example, the access point AP1).
Discover 2). The access point AP1 then floods its neighbor node status. At this time, since the access point AP1 knows the physical address of the terminal (for example, the mobile terminal MS1) belonging to itself, not only the adjacent node state but also the physical address of the terminal to which it belongs is flooded at the same time. As a result, all access points AP1 to AP4 can create a routing table, and at the same time a table as to which terminal belongs to which access point AP1 to AP4.

A more specific example will be described with reference to the schematic diagram of FIG. In the figure, the mobile terminal MS1 can communicate with the access point AP1 at the frequency of ch5, and the mobile terminal MS2 can communicate with the access point AP3 at the frequency of ch13. Further, the access points AP1 to AP3 are all communicating using the frequency of ch1. Here, when the IP packet is transmitted from the mobile terminal MS1 to the mobile terminal MS2,
It is transferred as follows.

The access points AP1 to AP3 are
Send hello packets to each other to understand the status of adjacent access points. Further, by flooding the physical addresses of its own adjacent nodes and terminals belonging to itself, all access points AP1 to AP1
P3 grasps the topology of the entire network.

The mobile terminal MS1 is the mobile terminal M
A frame in which the MAC address of S2 is designated as the destination address is transmitted to the access point AP1 using ch5.

Based on the MAC address of the mobile terminal MS2 included in the frame, the access point AP1 finds from the routing table held by itself the I of the access point AP3 to which the mobile terminal MS2 belongs.
P address and access point AP2 to be transferred next
Find out. Then, the destination is the IP of the access point AP3
The original frame is encapsulated in the IP packet specified as the address, and the encapsulated IP packet is transferred to the access point AP2 using ch1.

The access point AP2 transfers the encapsulated IP packet to the access point AP3.

The access point AP3 extracts the original frame from the encapsulated IP packet, and ch13
To transfer the frame to the target mobile terminal MS2. Conversely, the mobile terminal MS2 is the mobile terminal MS
When the IP packet is transmitted to the first packet, the original frame information is similarly encapsulated and transferred.

Access point AP1 thus moving
~ AP4 and mobile terminals MS1 to MS3, by simultaneously adding the information of the terminal belonging to the routing information between the access points AP1 to AP4, by transmitting to all the access points AP1 to AP4. , The mobile terminals MS1 to MS3 can communicate correctly.

In the WMLAN topology configuration shown in FIG. 1, in order to construct an environment in which each mobile terminal MS1 to MS3 can access the Internet via the WMLAN, an Internet access gateway connecting the WNLAN and the Internet is required. . Figure 8
This is an example. In the figure, GW is a gateway that provides access means to the Internet, and as will be described later, according to the scale of the network constructed by the WMLAN 40, there is only one gateway GW (gateway GW1 shown in FIG. 8). ,gateway
Configuration in which there are a plurality of 41 (gateway GW1 shown in FIG. 8
~ GW3) is possible. RT1 to RT3
Is a router connected between the gateway GW and the Internet network 43. As is well known, the router is provided for each of the gateways GW1 to GW3 as a device for relaying packets between different networks. In addition, WML
The configuration of AN 40 is common to that shown in FIG.

Next, the operation of the above structure will be described. First, the operation of the WMLAN 40 system having a single gateway GW1 will be described. WMLAN
In 40, when the power of an arbitrary access point (for example, access point AP1) is turned on, the access point AP1 realizes dynamic IP address allocation, for example, DHCP (Dynamic Host Configuration Pro).
to the IP address request packet requesting that the IP address be assigned using a protocol such as
Access point A, which is all the nodes of ET layer 22
Broadcast transfer to P2-AP4 and gateway GW1. As a result, since the IP address request packet reaches the gateway GW1, the gateway GW1
In response to this, the access point AP1 that has turned on the power source acquires its own IP address. At this time, the access point AP1 records the IP address of the gateway GW1.

In WMLAN40, since the wireless terminal (eg mobile terminal MS1) requests the IP address,
When the IP address request frame requesting the allocation of the IP address is transmitted, the access point AP1 which receives the frame sends the frame to the gateway GW1.
Encapsulate and transfer. The gateway GW1 records the physical address of the mobile terminal MS1 and the IP address to be given, and notifies the mobile terminal MS1 of the IP address. As a result, the mobile terminal MS1 receives the gateway G
It is possible to acquire its own IP address from W1.

The IP address includes a network ID (identifier) which is an identification number of the network. In the above process, since the gateway GW1 uses a specific network ID, all the access points AP1 to AP4 in the WMLAN are Wireless terminal (mobile terminal MS
1 to MS3) have the same network ID.

A wireless terminal (eg mobile terminal MS1) is another wireless terminal in the WMLAN (eg mobile terminal MS).
When a packet is sent to 3), the MAC address is obtained from the IP address of the mobile terminal MS3, which is the partner wireless terminal, so an address resolution request (Address Resolution Pr
otocol: ARP). That is, the mobile terminal MS
The access point AP1 that has received the ARP request frame from No. 1 IP-encapsulates it and sends it to the gateway GW1. As described above, the gateway GW1
Since the physical addresses of the mobile terminals MS1 to MS3 to which the P address is given are recorded, the access point AP
In response to the address resolution request from 1, the corresponding physical address of the mobile terminal MS3 is returned by an ARP response. As a result, the mobile terminal MS1 has the same WM.
From the IP address of mobile terminal MS3 in LAN40,
The physical address can be known, and the frame can be transmitted to the partner terminal.

Next, the operation of the WMLAN40 system having a plurality of gateways GW1 to GW3 will be described.

For example, when the power of the gateway GW1 is turned on, in order to confirm whether or not the other gateways GW2, GW3 are already operating, the gateway itself sends a packet for IP address server discovery and IP address request. To do. In response to this, the other gateways GW2, G
When there is a response from W3, the IP address is set to itself. At this time, a plurality of gateways GW2, GW
If there is a response from 3, select one of them.

When the gateways GW2, GW3 receive the IP address server discovery packet from any access point (for example, the access point AP1), each of the gateways GW2, GW3 responds. As a result, the access point AP1 has a plurality of gateways GWs.
2, receives a response from GW3, but requests an IP address from the gateway GW that returned the first response or the gateway GW with the smallest hop. At this time, the access point AP1 records the existence of the plurality of gateways GW2 and GW3 that have received the response.

Each gateway GW and access point A
Even after obtaining the IP address, P periodically discovers the IP address server, adds a new gateway GW, and updates the number of hops to each gateway GW.

When there is a request for an IP address from a wireless terminal (eg mobile terminal MS1), the access point AP1 which receives the request receives a plurality of gateways GW.
Select one from 1 to GW3 and IP
Send an address request. Selected eg gateway G
W1 creates an IP address response frame and
It is P-encapsulated and sent to the access point AP1 to which the mobile terminal MS1 belongs. Access point AP1 is I
The frame in the P capsule is taken out and sent to the mobile terminal MS1. Thereby, the mobile terminal MS1 connected to the gateway GW1 can acquire its own IP address. At this time, the access point AP1 normally selects the gateway GW1 that has acquired its own IP address, but cannot communicate with the gateway GW1.
The access point AP1 moves and the gateway GW
When the number of hops with respect to 1 is changed, another gateway with the shortest number of hops (for example, gateway GW2) may be selected. Multiple gateways GW1 to GW
Since each of the gateways 3 performs the IP address allocation process, it is necessary to determine the range of the IP addresses issued by the gateways GW1 to GW3 in order to prevent the same IP address from being given to different terminals. In the above, access points AP1 to A are assigned to the IP address.
It is preferable to give an appropriate expiration date to each of the P4 and mobile terminals MS1 to MS3 so that the IP address that has become unnecessary can be reused.

Communication destination terminal (eg mobile terminal MS
When an address resolution request (ARP request) for obtaining the physical address from the IP address of 3) is received from the wireless terminal (for example, mobile terminal MS1), the access point AP1 to which the mobile terminal MS1 belongs accesses all the gateways GW1 to GW3. To points AP1 to AP4,
The address resolution request is IP-encapsulated and transferred.
The gateways GW1 to GW3 having received the request send ARP requests to the routers RT1 to RT3 connected to the Internet 43, and the access points AP1 to AP4 send ARP requests to the wireless terminals belonging thereto. The wireless terminal (mobile terminal MS3) that receives this receives its own I
When it matches with the P address, an ARP response is returned. This reaches the mobile terminal MS1 which is a wireless terminal originating via the access points AP1 to AP4.

On the other hand, when the IP address for which the ARP request is issued is the Internet 43, each of the routers RT1 to RT3 connected to the Internet 43 responds. Upon receiving this, the access points AP1 to AP4 select the gateway (for example, the gateway G) selected based on the number of hops.
The received response is sent back to the mobile terminal MS1 which is the original wireless terminal via W1).

In this case, the gateways GW1 to GW
Routers RT1 to RT between W3 and the Internet network 43
Although the configuration shown in FIG. 3 has been connected, the gateways GW1 to GW
It is also possible to realize the functions of W3 and the routers RT1 to RT3 by one device, that is, the gateways GW1 to GW3. Since the access points AP1 to AP4 and the gateways GW1 to GW3 exchange routing information with each other to form an ad hoc network (MANET), the gateways GW1 to GW3 can also be regarded as a kind of the access points AP1 to AP4.

A wireless terminal such as a mobile terminal MS1
Is a router RT1 that connects the frame to another mobile terminal MS2 or mobile terminal MS3 or the Internet 43.
~ Send and receive to RT3, but MANET
By encapsulating the frame above with IP, access points AP1 to AP4 and gateways GW1 to GW3
However, the IP encapsulated one can be relayed. Therefore, in the configuration in which the functions of the gateways GW1 to GW3 and the routers RT1 to RT3 are unified, a frame in which the routers RT1 to RT3 have transmitted a frame is created in the gateways GW1 to GW3, and the frame is created by the I
P-encapsulated mobile terminals MS1 to M
It will be sent to S3. Further, the address resolution requests sent from the mobile terminals MS1 to MS3 are described in the embodiment as being handled by the gateways GW1 to GW3, but the same can be said.

The WMLAN in the above embodiment is the access points AP1 to AP4 and the gateways GW1 to GW.
If 3 is installed arbitrarily, a wireless link will be formed autonomously, so for example, communication resources (including Internet information) owned by individuals and organizations will be provided free of charge based on voluntary voluntary provision. It is suitable for a voluntary network constructed and operated by interconnecting established communication resources. The following can be considered as specific applications and services of the voluntary network.

The position information and traffic information from the access points installed along the road are used to support the actions of the elderly and the disabled. This service allows elderly people and people with disabilities to act safely. In addition, by transmitting position information and movement information from the elderly and disabled people to vehicles and motorcycles in transit, safe driving support can be provided to the driver, and it can be expected that traffic accidents will be reduced.

A child or the like is provided with a sensor, and the behavior information is received by a nearby access point and transferred to the home via the voluntary network. This caused an accident,
You can immediately detect an unexpected situation such as getting lost or abducted and respond to it.

The living environment is protected and improved by monitoring illegal dumping of oversized garbage, overtime dumping of domestic waste, illegal injection, and the like. This can be provided as an effective service to protect the comfortable living environment of the area from some people with bad manners.

Immediately contact the person, the police, or a neighbor with the detection of illegal entry into a house or the like, or theft of a car or bicycle. Thereby, the crime prevention effect can be expected.

It is considered that social and economic impacts will expand as the use of voluntary networks progresses in various fields. Some of these scenarios are as follows:

The voluntary network forms a regional intranet. It is thought that this will promote information sharing within the region and revitalize local communities and economies. Specifically, for example, not only in specific places such as airports and hotels where the effects of enhancing the administrative services, promoting the interaction of local residents, and activating the shopping street, etc. can be expected,
Voluntary networks provide constant access to the Internet through gateways in hospitals, towns, and anywhere else. As a result, it can be expected that the living environment will be convenient and socio-economic activities will be activated.

Utilizing the voluntary network,
Expand environmental sensing network over a wide area. Various sensors are installed in the environment to detect temperature, humidity, air and water pollution, and vibration. By continuously observing the environment and responding to abnormality detection, etc., maintaining a comfortable living environment, nature,
It can be expected to prevent man-made disasters. Voluntary networks form the basis of environmental business.

Some of the services realized by the voluntary network compete with the mobile phone service, such as the hot spot service, and may significantly affect the market and industrial structure of the mobile communication service. In a competitive environment, new business models and new applications may emerge.

As described above, the autonomous formation type wireless LAN system in this embodiment has a plurality of access points AP1 to AP1.
AP4 and gateways GW1 to GW3 that provide access means to the Internet 43 are used as constituent elements, and wireless links are autonomously established between the access points AP1 to AP4 and between the access points AP1 to AP4 and the gateways GW1 to GW3. Form and Mobile MS1-MS3
Between or mobile MS1-MS3 and gateway GW
Packet communication between 1 to GW3 is performed via one or a plurality of access points AP1 to AP4 via a wireless link.

In this case, access points AP1 to AP
4 and gateways GW1 to GW3 are installed at appropriate places, wireless links are autonomously established to the installed access points AP1 to AP4 and gateways GW1 to GW3, and this wireless link and one or more access points. Multi-hop packet communication via AP1 to AP4 becomes possible. Therefore, the access points AP1 to AP1
Easily install P4 and gateways GW1 to GW3,
A network can be easily formed.

Further, in this embodiment, each access point AP1 to AP4 communicates with the mobile terminals MS1 to MS3 and the first wireless device 11 and other access points AP.
1 to AP4 and a second wireless device 12 in communication therewith.

Thus, each access point AP1.about.
The AP 4 is different from the first wireless device 11 provided for communication with the mobile terminals MS1 to MS3 and another access point A.
Second wireless device 12 provided for communication with P1 to AP4
Are provided separately. Therefore, while the second wireless device 12 is designed so as to be able to perform multi-hop packet communication, the first wireless device 11 is operated by the mobile terminals MS1 to MS1.
It can be designed for MS3. As a result, the mobile terminals MS1 to MS3 can be used in the network without changing the design.

In this embodiment, the mobile terminals MS1 to MS1
Packet communication between the MS3s or between the mobile terminals MS1 to MS3 and the gateways GW1 to GW3 is performed, for example, as shown in FIG.
As shown in FIG.
Transfer between MS3 and access points AP1, AP4,
Transfer from the access point AP1 at the start point to the access point AP4 at the end point is performed separately.

In this case, the packet transferred from the mobile terminal MS1 on the transmitting side to the access point AP1 is rewrapped (encapsulated) at this access point AP1.
Is performed. Then, at the access point AP4 to which the mobile terminal MS3 on the receiving side belongs, a packet is extracted from the encapsulated one, and then sent out to the mobile terminal MS3 on the receiving side. That is, the mobile terminal M
If the network (WMLAN 40) is viewed from the S1 to MS3 side, the normal packet is simply transmitted and received, and the network can be utilized without being aware of the communication method between the access points AP1 to AP4.

In this embodiment, the access point AP
In packet transfer between 1 to AP4, the access point AP1 at the start point to the access point AP4 at the end point
The route to is automatically established.

In this case, the transmitting / receiving mobile terminals MS1,
A route (routing) from the start point to the end point of the access points AP1 and AP4, not between the MS3, is automatically established, and the packet can be transferred according to this route.

Further, in the present embodiment, the mobile terminals MS1 to MS1.
The MS 3 or access points AP1 to AP4 are fixedly or movably provided, and each access point AP1
To the access points AP1 to AP4 of the mobile terminals MS1 to MS3 belonging to AP4.
By transmitting and receiving each other, each access point AP
1-AP4 are themselves and other access points AP1-
All mobile terminals MS1 to MS3 belonging to AP4 are recognized.

As a result, the mobile terminals MS1 to MS3 are
Irrespective of whether or not the access points AP1 to AP4 move, each access point AP1 to AP4 is a wireless terminal belonging to not only the mobile terminals MS1 to MS3 to which it belongs but also all other access points AP1 to AP4. The address information of MS1 to MS3 can be grasped. Therefore, each of the access points AP1 to AP4 can specify the destination of the received packet based on the address information.

In this case, each access point AP1-A
It is preferable to send / receive the address information of the mobile terminals MS1 to MS3 belonging to P4 together with the route information to be sent / received between the access points AP1 to AP4.

In this way, each access point AP1.about.
The AP 4 can send and receive address information to and from each other, and can also send and receive route information at the same time. Therefore, regardless of whether or not the mobile terminals MS1 to MS3 and the access points AP1 to AP4 move, the destination and the route of the received packet can be specified based on the address information and the route information.

In this embodiment, each access point A
Mobile terminals MS1 to M to which P1 to AP4 belong
Each of the access points AP1 to AP4 exchanges information with each other to autonomously and decisively determine the channel number used when performing packet communication with S3.

As a result, the mobile terminals MS1 to MS3 are
The channel (frequency) numbers used for communication with the access points AP1 to AP4 to which the access points AP1 to AP4 belong are autonomously decentralized by information exchange between the access points AP1 to AP4. Therefore, the adjacent access point A
Channel numbers can be assigned so as not to cause interference between P1 to AP4.

In this embodiment, the mobile terminals MS1 to MS1
MS3 and access points AP1 to AP belonging to it
The communication procedure between 4 is the same as the conventional wireless LAN system,
The communication procedure between the access points AP1 to AP4 from the start point to the end point is performed by another communication procedure hidden from the mobile terminals MS1 to MS3.

In this case, when the network is viewed from the mobile terminals MS1 to MS3, the access point AP1
Since the communication method between the access points AP1 to AP4 is hidden, the mobile terminals MS1 to MS3 communicate with the access points AP1 to AP4 in the same communication procedure as before, without being aware of the communication method between the access points AP1 to AP4. Can communicate.

In this embodiment, as shown in FIG. 1, for example, the access point AP3 to which the mobile terminal MS3 belongs belongs to another access point AP4, and the data packet to the mobile terminal MS3 belongs immediately before. When the data packet is delivered to the original access point AP3, the data packet arriving at the original access point AP3 is transferred to the current access point AP4.

In this way, even if the access points AP1 to AP4 to which the mobile terminal MS3 belongs are changed one after another, a wireless link is autonomously formed between the access points AP1 to AP4. According to the point-to-point communication procedure, the current access point A is transmitted from the original access point AP3 via the wireless link.
The data packet is transferred to P4, and the mobile terminal MS3
It is possible to correctly transfer the data packet to.

In this embodiment, in the case where the gateway GW1 is one, the access points AP1 to AP4 or the mobile terminals MS1 to AP4 are connected from this gateway GW1.
While the MS 3 acquires the IP address, the gateway GW 1 records the physical addresses of the mobile terminals MS 1 to MS 3 and the given IP address, and the mobile terminals MS 1 to M
The physical address of the destination is returned in response to the address resolution request from S3.

In this case, the gateway GW1 is used to access the access points AP1 to AP4 and the mobile terminals MS1 to MS.
IP address is dynamically assigned to 3, and
The gateway GW1 centrally records the physical address of each mobile terminal MS1 to MS3 and the IP address for this. This allows any mobile terminal MS, for example
1 receives the address resolution request from the gateway GW1, the gateway GW1 can reply the physical address of the destination mobile terminal MS3, for example.
Can be correctly transmitted to the mobile terminal MS3 on the receiving side.

Further, in this embodiment, the gateways GW1 to GW1.
In a case where the GW3 has a plurality of configurations, one gateway GW1, for example, issues an IP address request to the other gateways GW2, GW3, so that the other gateways GW2, GW2
Presence / absence of GW3 is detected and other gateways GW2, GW
3 exists, the network identifier is known from the IP address, and the IP address is dynamically assigned in response to the IP address request from the access points AP1 to AP4 and the mobile terminals MS1 to MS3.

In this case, when an IP address request is issued from a certain gateway GW1 to the other gateways GW2, GW3, as long as the other gateways GW2, GW3 exist, the dynamically assigned IP address responds to the original gateway GW1. To be done. As a result, the gateway GW1 that has received the response can know the IP address and the network identifier included therein. Also, any mobile terminals MS1 to MS3 and access point AP1
When receiving the IP address request from AP4 to AP4, the gateways GW1 to GW3 can dynamically allocate the IP address in response to the inquired mobile terminals MS1 to MS3 and the access points AP1 to AP4.

Further, for example, when the access point AP1 seeking an IP address broadcasts an IP address server discovery packet and the gateways GW1 to GW3 receiving it reply, the access point AP1 finds one of the discovered gateways. An IP address request packet is sent to the device to obtain the IP address.

Thus, even if there are a plurality of gateways GW1 to GW3 that have responded to the IP address server discovery packet, the access point AP1 seeking the IP address
Sends an IP address request packet to only one of the selected gateways GW1, the gateway GW1
A wireless link with is autonomously established, and a single IP address can be received from the gateway GW1.

Also, the gateway GW1 in this embodiment.
~ GW3 or access points AP1 to AP4 periodically discover the IP address server, update the hop count and the like with the plurality of gateways GW1 to GW3, and pass through the gateways GW1 to GW1 to connect to the Internet 43.
GW3 is selected.

In this case, the gateways GW1 to GW3 and the access points AP1 to AP4 periodically discover the IP address server to obtain a plurality of gateways GW1 to GW1.
The number of hops with the GW 3 and the like are updated. Therefore, when the mobile terminals MS1 to MS3 access the Internet 43, the optimum gateways GW1 to GW3 can be selected.

In this embodiment, the access points AP1 to AP1.
When the AP 4 receives a response to the IP address server discovery from the plurality of gateways GW1 to GW3, the plurality of gateways GW1 to GW3 are recorded.

As a result, each of the access points AP1 to AP1
AP4 receives a plurality of gateways GW1-G
You can know the existence of W3.

In the present embodiment, the access points AP1 to AP1.
When the AP4 receives the IP address server discovery and the IP address request from the mobile terminals MS1 to MS3, the AP4 encapsulates the IP address server and the selected gateway GW1.
~ Transfers to GW3 and gives an IP address.

In this case, for example, upon receipt of the IP address server discovery and IP address request from the mobile terminal MS1, the access point AP1 to which it belongs receives the IP address server discovery and IP address request IP-encapsulated in the selected gateway GW1. Forward. This causes the mobile terminal MS1 to select the selected gateway G
A wireless link with W1 is autonomously established, and an IP address can be independently received from the selected gateway GW1.

In this embodiment, for example, the mobile terminal MS1
When an address resolution request is made by the access point AP1, the access point AP1 receiving it requests it to all gateways GW1.
To GW3 and access points AP1 to AP4, the gateways GW1 to GW3 use the Internet 43
To the routers RT1 to RT3 connected to the mobile terminals MS1 to MS3 to which the access points AP1 to AP4 belong.
When the reply is transmitted to all the routers RT1 to RT3 via the respective gateways GW1 to GW3, the response via the gateway GW1 that has already been selected is selected and the physical destination of the mobile terminal MS1 is selected. I will try to return the address.

In this case, when the mobile terminal MS1 makes an address resolution request, the address resolution request is sent to all the mobile terminals MS1 to MS3 and the gateways GW1 to GW1.
GW3, routers RT1 to RT3, access point AP
1 to AP4, but a plurality of routers RT1 to RT
When there is a response from the gateway 3 through the respective gateways GW1 to GW3, the response via the gateway GW1 that has already been selected is selected, and the physical address corresponding to the destination IP address is sent to the mobile terminal MS1. Can be returned.

Further, in this embodiment, for example, the gateway G
When W1 receives an IP packet addressed to the mobile terminal MS3 from the Internet 43, the W1 transfers the packet from itself via the wireless LAN system (WMLAN40), or
The configuration information of the wireless LAN system and its respective access point A, which stores whether or not to detour to the other gateways GW2 and GW3 and enter the wireless LAN system from there
The determination is made based on the information of the mobile terminals MS1 to MS3 belonging to P1 to AP4.

In this case, when the gateway GW1 receives an IP packet addressed to the mobile terminal MS3 from the Internet 43, the gateway itself transfers the packet via the wireless LAN system or the other gateways GW2, GW.
The gateway GW1 can immediately determine whether to detour to 3 and enter the wireless LAN system from there.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, as a wireless terminal, in addition to the mobile terminal in the embodiment, a personal digital assistant (PDA) with a LAN card is used.
(Personal Digital Assistance) or a laptop can be applied.

[0149]

According to the autonomous formation type wireless LAN system of the first aspect, an access point and a gateway can be easily installed to easily form a network.

According to the autonomous formation type wireless LAN system of claim 2, the wireless terminal can be used for the network without changing the design.

According to the autonomous formation type wireless LAN system of claim 3, the network can be utilized without being aware of the communication system between the access points.

According to the autonomous formation type wireless LAN system of claim 4, a route from the start point to the end point of the access point can be automatically established.

According to the autonomous formation type wireless LAN system of claim 5, the destination of the packet received by each access point can be specified.

According to the autonomous formation type wireless LAN system of claim 6, the destination and the route of the packet received by each access point can be specified.

According to the autonomously forming wireless LAN system of claim 7, channel numbers can be assigned so that interference does not occur between adjacent access points.

According to the autonomous formation type wireless LAN system of claim 8, the wireless terminal can communicate with the access point by the system of the same communication procedure as before.

According to the autonomous formation type wireless LAN system of claim 9, it is possible to correctly transfer the data packet to the wireless terminal even when the access points to which the wireless terminal belongs are changed one after another.

According to the autonomous formation type wireless LAN system of the tenth aspect, the gateway can dynamically assign the IP address in response to the inquired wireless terminal or access point.

According to the autonomously forming wireless LAN system of claim 11, the access point seeking an IP address is capable of autonomously establishing a wireless link with one selected gateway and receiving a single IP address. You can

According to the autonomously forming wireless LAN system of claim 12, the optimum gateway can be selected when the wireless terminal accesses the Internet.

According to the autonomous formation type wireless LAN system of claim 13, the existence of a plurality of gateways can be known at each access point.

According to the autonomous formation type wireless LAN system of the fourteenth aspect, the wireless terminal can autonomously establish the wireless link with the selected gateway and can receive the IP address independently.

According to the autonomous formation type wireless LAN system of claim 15, it is possible to select the response via the already selected gateway and return the physical address corresponding to the IP address of the destination.

According to the autonomous formation type wireless LAN system of claim 16, when the gateway receives an IP packet from the Internet, the gateway transfers the packet via the wireless LAN system or detours it to another gateway. From there, it is possible to immediately determine whether to enter the wireless LAN system.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram showing a topology configuration of a WMLAN network showing an embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing the software architecture of WMLAN.

FIG. 3 is a block diagram showing a protocol stack for LAN emulation.

FIG. 4 is a block diagram showing a protocol stack of IP-IP encapsulation.

FIG. 5 is a schematic configuration diagram when the communication distance of MANET is smaller than twice the communication distance of WLAN.

FIG. 6 is a schematic configuration diagram when the communication distance of MANET is twice or more the communication distance of WLAN.

FIG. 7 is a schematic explanatory diagram showing another topology configuration of the WMLAN network.

FIG. 8 is a schematic configuration diagram showing a connection between the WMLAN and the Internet.

[Explanation of symbols]

11 First wireless device 12 Second wireless device 40 WMLAN (Wireless LAN system) 43 Internet AP1 to AP4 access points GW1 to GW3 gateway MS1 to MS3 mobile terminals (wireless terminals) RT1-RT3 router

Claims (16)

[Claims] 1. A wireless terminal, comprising a plurality of access points and a gateway that provides access means to the Internet as constituent elements, and autonomously forming wireless links between the access points and between the access point and the gateway. An autonomous formation type wireless LAN system characterized in that packet communication between terminals or a wireless terminal and the gateway is performed via one or a plurality of the access points and the wireless link. 2. The autonomous formation of claim 1, wherein each access point has a first wireless device in communication with the wireless terminal and a second wireless device in communication with another access point. Type wireless LAN system. 3. Packet communication between the wireless terminals or between the wireless terminals and the gateway, transfer between the wireless terminals and the access point on the transmission / reception side, and the access from the access point at the start point to the end point. 3. The autonomous formation type wireless LAN system according to claim 1, wherein the transfer is performed separately for transfer to a point. 4. The autonomous formation type wireless LAN system according to claim 1, wherein in the packet transfer between the access points, a route from the access point at the start point to the access point at the end point is automatically established. . 5. The wireless terminal or the access point is fixedly or movably provided, and each access point sends and receives address information of a wireless terminal belonging to the access point to and from each other. The autonomous formation type wireless LAN system according to claim 1, wherein the wireless terminal belonging to another access point is recognized. 6. The autonomous formation type wireless LAN system according to claim 5, wherein address information of the wireless terminal belonging to each access point is transmitted and received together with route information transmitted and received between the access points. 7. The access point exchanges information to determine a channel number used when each access point performs packet communication with the wireless terminal to which the access point belongs, in an autonomous decentralized manner. 1. The autonomous formation type wireless LAN system described in 1. 8. The communication procedure between the wireless terminal and the access point belonging to the wireless terminal is equivalent to that of a conventional wireless LAN system, and the communication procedure between the access point from the start point to the end point is hidden from the wireless terminal. The autonomous formation type wireless LAN system according to claim 1, wherein 9. When an access point to which the wireless terminal belongs is transferred to another access point and a data packet for the wireless terminal is delivered to the original access point to which it last belonged, 2. An inter-access point communication procedure for transferring a data packet arriving at another access point to the current access point.
The described autonomous formation type wireless LAN system. 10. When the gateway has a plurality of configurations, one gateway issues an IP address request to the other gateway to detect the presence or absence of the other gateway, and if the other gateway exists, the IP address is detected. 2. The autonomous formation type wireless LAN system according to claim 1, wherein the network identifier is known and a response is made to an IP address request from the access point or the wireless terminal. 11. The access point seeking an IP address broadcasts an IP address server discovery packet, the gateway that receives it responds, and sends an IP address request packet to one of the discovered gateways. , The IP address is acquired, the autonomously forming wireless L according to claim 10.
AN method. 12. The gateway or the access point periodically discovers an IP address server, updates the number of hops with a plurality of gateways, etc., and selects a gateway through which to connect to the Internet. The autonomous formation type wireless LAN system according to claim 11. 13. The autonomous formation type wireless LAN system according to claim 11, wherein when the access point receives a response to the IP address server discovery from a plurality of gateways, the plurality of gateways are recorded. 14. When the access point receives an IP address server discovery and an IP address request from the wireless terminal, IP encapsulates the IP address, transfers it to a selected gateway, and gives an IP address. The autonomous formation type wireless LAN system according to claim 10. 15. When the wireless terminal makes an address resolution request, the access point receiving the request forwards it to all the gateways and the access points, and the gateway sends the access point to the router connected to the Internet. Transfers to all the wireless terminals to which it belongs, and when there are responses from multiple routers via their respective gateways, the response via the gateway that has already been selected must be selected and returned to the wireless terminals. 11. The autonomous formation type wireless LAN system according to claim 10. 16. When the gateway receives an IP packet addressed to the wireless terminal from the Internet, transfers the packet from itself via a wireless LAN system or diverts it to another gateway, and then the wireless L
A wireless L that stores in itself whether to enter the AN system
16. The autonomous formation type wireless LAN system according to claim 15, wherein the determination is made based on the configuration information of the AN system and the wireless terminal information belonging to each access point.