JP2003304572A - Communication system and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system and communication method whereby a mobile node (MN) registers its presence to a gateway node (GN) to attain its own communication even when the MN is located at the outside of a cell area of the GN. <P>SOLUTION: This invention provides the communication system having a fixed station 1 and a plurality of mobile stations 2a, 2b,... and the communication method adopted by the communication system. One feature of the system and the method is that when the mobile station 2a not belonging to the cell area of the fixes station 1 makes a communication request to the fixed station 1, the mobile station 2a makes multi-hop communication with the other mobile station 2b belonging to the cell area of the fixed station 1, the mobile station 2b makes single hop communication with the fixed station 1, and the fixed station 1 calculates a communication route of the mobile station 2a while referencing an NN-DB (Neighbor Node Database) 4 and a resource management DB 5. <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 routing control in, for example, wireless multi-hop communication, and in particular, a fixed node gateway node (hereinafter referred to as GN) connected to an external network is arranged in a macro cell. A centralized control method that uses a hybrid communication method that appropriately uses a certain control mode and a relay mode that is a micro cell is adopted, and communication by a mobile node (hereinafter referred to as MN) outside the GN cell area is also possible. The present invention relates to a communication system and a communication method.

[0002]

2. Description of the Related Art Conventionally, in routing control in wireless multi-hop communication, the cell radius of each node is fixed, and in the communication system, each node autonomously performs routing. Here, a main protocol in such routing control is, for example, AODV.
(Ad-hoc On-Demand Vector Routing) and DSR (Dynam
icSource Routing) etc. In these protocols, MN, which is a mobile station existing in the network
As a result, the adjacent information is grasped and the routing control is autonomously performed. Specifically, first, a route request packet (hereinafter, referred to as RREQ) packet is broadcast from the transmission source MN. And this RREQ
When the packet is received by the destination MN, a route reply (Route Reply, hereinafter referred to as RREP) packet is returned from the destination MN by unicast to the source MN. In this way, the RREP packet from the destination MN is received by the source MN, whereby a series of routing control is completed.

It should be noted that this routing control can be said to be the same in the conventional system in which the fixed station GN is arranged. In the conventional type, the GN only has a function substantially equivalent to that of the MN, and its role is only to expand the network scale or connect to an external network.
This is because there is no control on the network.

However, it is generally known that in wireless communication, the transmission band of the entire network becomes narrow due to radio wave interference and packet collision.

In particular, in the case of performing the above-mentioned wireless multi-hop communication, an RREQ packet is broadcast from the node of the transmission source, and a large amount of routing control packets are leaked to the network. As a result, the network bandwidth is pressured. Furthermore, as the number of terminals increases, the overhead of control packets increases, radio interference and packet collisions increase sharply, route control becomes complicated, and communication is virtually impossible. Further, in the above-described related art, since wireless resources, which are limited resources, are wastefully consumed, it is also desired to efficiently use wireless resources to reduce the control packet amount.

That is, it is generally known that in wireless communication, the transmission band of the entire network becomes narrow due to such radio wave interference and packet collision.

In particular, when performing the above-mentioned wireless multi-hop communication, an RREQ packet is broadcast from the source node, and a large amount of routing control packets are leaked to the network. As a result, the network bandwidth is pressured. Furthermore, as the number of terminals increases, the overhead of control packets increases, radio interference and packet collisions increase sharply, route control becomes complicated, and communication is virtually impossible. Further, in the above-described related art, since wireless resources, which are limited resources, are wastefully consumed, it is also desired to efficiently use wireless resources to reduce the control packet amount.

In view of the above point, the present applicant has estimated that the source node transmits a source route request (hereinafter referred to as SRREQ) packet to the GN by single-hop communication, and the GN that receives the SRREQ estimates it. A route calculation is performed based on the topology information, and the result is a source route reply (hereinafter referred to as SRRE).
It has previously proposed a method of carrying out an accurate route construction by sending the packet in a packet and sending it back to all the nodes related to the route construction in a single hop.

[0009]

However, in the above prior art, when the MN is outside the cell area of the GN, the SRREQ packet cannot be transmitted, so that the connection request cannot be made and the communication area is expanded. Requires many base stations. In addition, communication is impossible when the base station fails. It is hoped that even if the MN is outside the GN cell area, the existence of its own node is registered in the GN to enable communication.

The present invention has been made in view of the above problems, and an object thereof is to adopt a centralized control system by GN in which communication conditions of a control packet and a packet of actual data are differentiated by a transmission mode. By doing so, it is possible to reduce the amount of control packets flowing out on the network, and avoid a situation where the network bandwidth is compressed, radio wave interference, and packet collision. Further, the centralized control method by the GN is adopted to allow the GN to grasp the adjacent information, thereby eliminating the need for autonomous route construction between the MNs. Further, it is to make the GN grasp the resource management information on the network and efficiently use the limited network resource. And, in particular, even when the MN is located outside the cell area of the GN, the existence of the own node is registered in the GN, and further communication by the MN is possible.

[0011]

In order to achieve the above object, according to a first aspect of the present invention, in a communication system in which at least a mobile station and a fixed station are capable of communicating via a wireless network, adjacent information is provided. A plurality of mobile stations that periodically transmit the adjacent information accumulated in the first database to a fixed station and the adjacent information of all the mobile stations existing within a predetermined range. And a third database for storing resource information, and a fixed station for updating the stored contents of the second database with adjacent information transmitted from the mobile station, the cell of the fixed station When one mobile station that does not belong to the area makes a communication request to the fixed station, the one mobile station communicates with other mobile stations that belong to the cell area of the fixed station by multi-hop communication. The request information is transmitted, the other mobile station transfers the communication request information to the fixed station by single-hop communication, and the fixed station refers to the second and third databases based on the communication request information and A communication system is provided which is characterized by calculating a communication route of a mobile station.

In the second aspect of the present invention, if one mobile station that does not belong to the fixed station cell area cannot specify another mobile station that belongs to the fixed station cell area. There is provided a communication system further characterized by transmitting the communication request information by flooding by multi-hop communication.

Further, in the third aspect of the present invention, when another mobile station belonging to the cell area of the fixed station receives the communication request information transmitted by the flooding by the multi-hop communication, the other request is transmitted. There is provided a communication system further characterized by stopping transfer of the communication request information by the mobile station to a further mobile station.

In the fourth aspect of the present invention, the fixed station, which has received a communication request from the one mobile station via another mobile station, has a station adjacent to the mobile station itself or adjacent to itself. In the case of another fixed station, both the communication route passing through the fixed station and the communication route not passing through the fixed station are calculated, and the communication route is determined by selecting the communication route having the smaller route cost than the both, and A communication system further characterized in that, when a station adjacent to a mobile station is not itself or another fixed station adjacent to the mobile station, only a communication route through the fixed station is calculated and the communication route is determined. It

In the fifth aspect of the present invention, when the mobile station of the transmission destination and the mobile station of the transmission source communicate with each other based on the determined communication route, When it does not belong to the fixed station or the cell area of another fixed station adjacent to the fixed station, the mobile station of the origin of the relay of the mobile station of the transmission destination that belongs to the cell area is specified, and the relay of the mobile station of the transmission destination is specified. There is provided a communication system further characterized by communicating via a mobile station of origin.

Further, in the sixth aspect of the present invention, the adjacency information includes at least node identification information related to other mobile stations existing in the adjoining range of one mobile station, and the resource information is the network. There is provided a communication system further characterized by including at least information on resources and whether or not they are used, and user identification information.

In a seventh aspect of the present invention, at least a plurality of mobile stations having a first database for storing adjacent information and a second database for storing adjacent information of all mobile stations existing within a predetermined range. In a communication method by a communication system in which a fixed station having a third database for storing resource information is capable of communicating via a wireless network, adjacent information stored in the first database by each mobile station is provided. Is periodically transmitted to the fixed station, the fixed station updates the stored content of the second database with the adjacent information transmitted from the mobile station, and one mobile station not belonging to the cell area of the fixed station When making a communication request to the fixed station, the one mobile station requests another mobile station belonging to the cell area of the fixed station by multihop communication. Information is transmitted, the other mobile station transfers the communication request information to the fixed station by single-hop communication, and the fixed station refers to the second and third databases based on the communication request information. At the same time, there is provided a communication method characterized in that the communication route of the one mobile station is calculated.

In the eighth aspect of the present invention, if one mobile station that does not belong to the cell area of the fixed station cannot specify another mobile station that belongs to the cell area of the fixed station. There is provided a communication method further characterized by transmitting the communication request information by flooding by multi-hop communication.

Further, in the ninth aspect of the present invention, when another mobile station belonging to the cell area of the fixed station receives the communication request information transmitted by the flooding by the multi-hop communication, the other mobile station receives the communication request information. There is provided a communication method further characterized by stopping transfer of the communication request information to the mobile station by the mobile station.

In the tenth aspect of the present invention, the fixed station, which has received a communication request from the one mobile station via another mobile station, has a station adjacent to the mobile station itself or adjacent to itself. In the case of another fixed station, both the communication route passing through the fixed station and the communication route not passing through the fixed station are calculated, and the communication route is determined by selecting the communication route having the smaller route cost than the both, and A communication method is further provided, wherein when the station adjacent to the mobile station is not itself or another fixed station adjacent to the mobile station, only the communication route through the fixed station is calculated and the communication route is determined. It

[0021] In the eleventh aspect of the present invention, when communication is performed between the transmission destination mobile station and the transmission source mobile station based on the communication route determined above, the transmission destination mobile station is When it does not belong to the fixed station or the cell area of another fixed station adjacent to the fixed station, the mobile station of the origin of the relay of the mobile station of the transmission destination that belongs to the cell area is specified, and the relay of the mobile station of the transmission destination is specified. There is provided a communication method, which is further characterized by performing communication via a mobile station as an origin.

Further, in the twelfth aspect of the present invention, the adjacency information includes at least node identification information of another mobile station existing in the adjacency range of one mobile station, and the resource information is a network. There is provided a communication method further characterized by including at least information on resources and whether or not they are used, and user identification information.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> First, FIG. 1 shows a conceptual diagram of a communication system according to a first embodiment of the present invention. As shown in FIG. 1, the communication system according to the present embodiment is characterized by routing control in wireless multi-pop communication, and is a fixed station GN1 and a mobile station MN2 (2a, 2b ...). And have. Then, the MN2 (2a, 2b ...)
3 (3a, 3b ...) Called NN-DB. Further, the GN1 has all the MNs 2a and 2b belonging to its own cell.
Is provided with a NN-DB 4 and a resource management database (hereinafter referred to as a resource management DB) 5.

The first database according to the claims corresponds to the NN-DB3, and the second database corresponds to the NN-DB3.
Corresponds to DB4, the third database is the resource management DB
Equivalent to 5. However, the relationship is not limited to this.

As the MNs 2a, 2b ..., it is assumed that the mobile terminals are mobile. The GN 1 is assumed to be a fixed wireless terminal connected to each other by wire and also connected to an existing network such as the Internet. Both of them perform communication by a bidirectional wireless link, and the details thereof will be described later, but one of the features is that they have two transmission modes such as a control mode and a relay mode.

Here, in the NN-DBs 3a, 3b ..., The MNs 2a, 2 adjacent to the node ID of each MN 2a, 2b.
Information such as a node ID of b ... and received power (hereinafter referred to as “adjacent information”) is stored. Each MN 2a, 2b ...
Uses a so-called "Hello protocol", which will be described in detail later, to periodically acquire data of the adjacent MNs 2a, 2b ... And update the contents of the NN-DBs 3a, 3b ... With the acquired data.

Further, the NN-DB4 of the GN1 stores the adjacency information of all the MNs 2a, 2b ... Which belong to the own cell. The NN-DB4 of this GN1 can be referred to from other GNs, and the content is MN
It is designed to be regularly updated based on the update information from 2a, 2b ....

On the other hand, in the resource management DB 5 of the GN 1, information such as network resources (frequency, used ch, code, etc.), presence / absence of use, user ID, etc.
Called) is accumulated. This resource management DB5 is
It can be referenced from other GNs. The contents of the resource management DB 5 are updated, for example, every time the use status of network resources changes.

The communication system of the present invention includes, as transmission modes, low-speed transmission and a control mode corresponding to macro cells,
It uses a hybrid system that selectively uses high-speed transmission and relay mode compatible with microcells.

Under the hybrid system, control data is single-hop communicated in the control mode, and user data is multi-hop communicated in the relay mode.

As a result, in the present embodiment, it is possible to reduce the amount of control packets flowing out on the network and keep it at a fixed amount.

Further, GN1 and each MN2a, 2b ...
Although details will be described later, the Hello protocol and the route construction algorithm are implemented, and the Hello interval and the adjacent information update interval are stored in advance in each MN 2a, 2b.

When there is a route request from the MNs 2a, 2b ... At the GN1, routing control is performed according to the route construction algorithm.

The communication system and method according to the present embodiment are premised on bidirectional communication, and allow single-hop communication only in the control mode and multi-hop communication in the data transfer mode. Also, by changing the used bandwidth, two transmission modes with different cell radii are realized. Alternatively, for example, a subcarrier modulation method and a variable rate technology that changes the transmission rate and the cell radius by changing the multi-level number / coding rate are used, but the invention is not limited to these.

Next, referring to FIG. 2, the NN-DB 3a,
3b ..., 4 will be described in more detail.

FIG. 2A shows an example of the format of the NN-DBs 3a, 3b, ..., And FIG. 2B shows the NN-D.
An example of the format of B4 is shown.

First, as shown in FIG. 2A, the MN
2a, 2b ... NN-DBs 3a, 3b ... are node IDs (Neighbor N) of adjacent MNa, 2b.
ode [1] ... [n]) and its received power P1 ... Pn. Further, FIG. 2 (b)
NN-DB4 of GN1 is adjacent to all MNs (Mobile Node [1] ... [m]) in its own cell.
Node ID of (MobileNode [1] ... [s], ..., Mobile Node
[1] ... [t]) and its received power P1-1 ... P1-s, ..., Pm-1
... The format is such that Pm-t is accumulated.

Here, as shown in FIG. 2C, G
Further detailed description will be made assuming that there are six MN2a-2f in the cell of N1. In the figure, the range indicated by the broken line means the range adjacent to the MNs 2a-2f shown at the center thereof.

In this case, the NN-DB 3a of the MN 2a
Includes the node I of MN 2d, 2e, 2f as neighbor information.
D and received powers P2a-2d, P2a-2e, P2a-2f are accumulated (see FIG. 3A). NN-DB3b of MN2b
The node ID of the MN 2f and the received power P2b-2f are stored as the adjacent information (see FIG. 3B). MN2
In the NN-DB 3c of c, the node ID of the MN 2f and the received power P2c-2f are stored as the neighbor information (FIG. 3).
(See (c)). In the NN-DB 3d of the MN 2d, the node IDs of the MNs 2a and 2e and the respective reception powers P2d are stored as the adjacency information.
-2a and P2d-2e are accumulated (see FIG. 3 (d)). M
In the NN-DB 3e of the N2e, the MN2 is used as the neighbor information.
The node IDs a and 2d and the received powers P2e-2a and P2e-2d are accumulated (see FIG. 3 (e)). NN2f NN-
In the DB 3f, the node IDs of the MNs 2a, 2b and 2c and the received powers P2f-2a, P2f-2b and P2f-2c are stored as the adjacency information (see FIG. 3 (f)). Then, the NN-DB 4 of the GN 1 stores the adjacency information (node ID, each reception power) of all the MNs 2a-2f (FIG. 3).
(See (g)).

Next, the resource management DB 5 of the GN 1 will be described in more detail with reference to FIG.

Here, the contents of the resource management DB 5 of the GN 1 corresponding to the situation shown in FIG. 4A (here, ch
The management will be described as an example) and will be described with reference to FIG.

In FIG. 4A, the solid line means that communication is in progress, and the broken line means that there is an adjacency relationship. In the situation of FIG. 4A, the MNs 2b, 2c,
2f is communicating on ch1 and MN2a, 2d, 2
While g is communicating with chn, such information is
As shown in FIG. 4B, it is stored and managed in the resource management DB 5. Note that unused channels are null.

In this way, the resource management DB 5 uses the used frequency c
By managing h, each MNa, 2b ...
It is also possible to perform hech negotiation.

The routing control by the communication system according to the first embodiment of the present invention will be described in detail below with reference to the flowchart of FIG.

Here, unless otherwise indicated, MN2
a, 2b ... MN2, NN-DB 3a, 3b ... NN-
Collectively referred to as DB3, the description will proceed.

In the first embodiment, in the wireless multi-hop network, by performing the routing control by the centralized control method by the GN1 using the adjacency information of the NN-DB4 and the resource information of the resource management DB5, the wireless resource is controlled. One of the features is that the control packets flowing on the network are reduced by effectively utilizing the.

Based on this, the routing control will be described in detail below.

Now, when the MN2 becomes available (step S1), the first thing that the MN2 connected to the network does is a search for the GN1 (step S1).
2).

There are two methods for searching for GN1 as shown in FIG.

That is, one method is a method using a gateway advertisement (hereinafter referred to as G-Advertisement). In this method, GN1 broadcasts G advertisements periodically. Then, the MN2 connected to the network confirms the existence of the GN1 based on the presence or absence of the G advertisement transmitted periodically.

On the other hand, another method is the gateway solicitation (G-
Solicitation (hereinafter referred to as “G request”). That is, in this method, the MN 2 transmits a G request at a desired timing. And G who received the G request
N1 immediately sends a G advertisement. Thus, the MN2 connected to the network confirms the existence of the GN1 by this G advertisement. As described above, in the latter method, the MN 2 can immediately perform the gateway search without waiting for the G advertisement.

Now, when the MN1 searches the GN1 and confirms its existence (step S3), the MN2 then examines the neighbor information by the Hello protocol and periodically updates the neighbor information to the GN1 (step S3). S4 to S6).

Here, the Hello protocol will be described in more detail with reference to the flowchart of FIG. Here, for convenience of explanation, two MNs 2a,
It is assumed that processing by the Hello protocol is performed between 2b.

First, immediately before the MN2b is activated, a Hello packet is transmitted to the MN2b. Then, when the MN2b is booted, He that is empty from the MN2b is
The Ilo packet is transmitted to the MN 2a. In the MN2a, the Hello packet from this MN2b causes the MN to
It is recognized that reception from 2b is possible.

Then, the MN2a transmits a Hello packet listing the MN2b to the MN2b. MN
In 2b, by receiving this Hello packet,
It is confirmed that MN2a has recognized its own existence. Then, from the MN2b, the He that lists the MN2a
The Ilo packet is transmitted to the MN 2a.

Thus, in MN2a, this Hello
By receiving the packet, it is confirmed that the MN 2b has recognized its own existence. Then, a Hello packet listing MN2b is sent from MN2a.
b.

Hereinafter, the series of processes will be described in more detail with reference to FIGS. 8 to 11.

8 (a), 9 (a) and 10
The circular range shown by the broken line in (a) and FIG. 11 (a) means the adjacent range of the MNs 2a to 2f located at the center thereof.

First, in the initial state (see FIG. 8A), all MN2s in the own cell are stored in the NN-DB4 of GN1.
Adjacency information (node ID, received power) of b-2f is accumulated (see FIG. 8B). In this example, NN of GN1
-From DB4, it is MN that is located in the adjacent range of MN2b.
2f and MN2c are located adjacent to MN2f and M
It can be seen that MN2e is located in the adjacent range of N2d, MN2d is located in the adjacent range of MN2e, and MN2c and 2b are located in the adjacent range of MN2f.

Assuming that the MN2a has booted, a Hello packet will be transmitted from the MN2a (see FIG. 9 (a)). However, at this stage, since the adjacency information has not been updated from MN2a to GN1, the contents of NN-DB4 of GN1 have not been updated (see FIG. 9 (b)).

Further, the MNs 2d, 2e, which are located in the adjacent range where the Hello packet is received from the MN2a,
When the Hello packet is returned from the 2f to the MN 2a (see FIG. 10A), the content is stored in the NN-DB 3a of the MN 2a as the adjacent information (FIG. 10).
(See (b)). Then, when this neighbor information is updated to GN1 by MN2a, NN-DB of GN1 is updated.
The neighbor information of MN2a is newly added to 4 and updated (see FIG. 10 (c)).

When the Hello packet transmitted from the MN2a is received by the MN2d, 2e and 2f (see FIG. 11A), the NN-DB of the MN2d, 2e and 2f is received.
The adjacent information of 3d, 3e, and 3f is updated (FIG. 11).
(B), (c), (d)).

That is, more specifically, in this example, MN2
In the NN-DB 3d of d, the MNs 2a, 2
The node ID of e and the received powers P2d-2a and P2d-2e are stored (see FIG. 11B). Then, in the NN-DB 3e of the MN 2e, the node IDs of the MNs 2a and 2d and the reception powers P2e-2a and P2e-2d are stored as the adjacency information (see FIG. 11 (c)). Furthermore, NN of MN2f
-In the DB 3f, the MNs 2a, 2b, 2c are used as the neighbor information.
Node IDs and received powers P2f-2a, P2f-2b, P2f-2
c is accumulated (see FIG. 11 (d)).

Then, this adjacency information is converted into MN2d, 2
When updated to GN1 by e or 2f, the G
Neighbor information of MN2d, 2e, 2f is newly added to the NN-DB4 of N1 and updated (FIG. 11).
(See (e)).

Here, the description returns to FIG. 5 again. After the above processing, when a communication request is issued from the MN 2 (step S7), processing based on a route establishing algorithm, which will be described in detail later, is executed (step S8).

The route establishing algorithm executed in step S8 of FIG. 5 will be described in detail below with reference to the flowchart of FIG.

When a communication request is issued from a certain MN2, the existence of a communicable GN1 is confirmed (step S1).
1). If there is a communicable GN1, MN2
Sends an SRREQ packet to GN1 (step S
12).

Then, the GN1 which has received this SRREQ packet, the destination node (Destination Node and below, D
It is confirmed whether or not (referred to as N) exists in the NN-DB 4 (step S13). If it is not possible to confirm the presence of the communicable GN1 in step S11, and if it is determined that the DN does not exist in the NN-DB4 in step S13, it is processed as a route establishment failure (step S14). .

On the other hand, DN is NN in step S13.
-If it exists in DB4, GN1 is the G to which DN belongs
It is confirmed whether N is adjacent or the same GN (step S15). If the GN to which the DN belongs is confirmed to be adjacent or the same GN, a route without the GN1 (Gatewayless Route) may be more efficient than a route with the GN1 (Gateway Route). , Source Route (SR; Source Route) and Route Cost (RC; Ro) for both Gateway Route and Gatewayless Route
ute Cost), and a route with a small RC is selected (step S16). On the other hand, when it is confirmed in step S15 that the GN to which the DN belongs is not adjacent or the same GN, only the Gateway Route is calculated to determine the route (step S
19).

In the communication system and method according to the present embodiment, Dijkstra's shortest path algorithm or the like is used for route calculation of MN-MN and MN-GN. However, this is an example, and the present invention is not limited to this.

The MN-MN link cost is "1" regardless of the number of hops, and the GN-GN link cost is "1" regardless of the distance. Thus, GN1
When the route is determined by, the GN1 transmits an SRREP packet describing the used channel and the source route to the MN2 to all related nodes (source route between the source node and the destination node) (step S17).

MN2 receiving this SRREP packet
Determines a channel to be used based on the information and creates a routing table (step S18). Thus, the user data is transmitted and received in the relay mode (step S2).
0). That is, various packets are unicast in the relay mode based on the source route information included in the SRREP packet. Note that the existing wired algorithm (RI
P, OSPF, etc.) is used.

Here, the difference between the "route establishment algorithm" and the "OSPF" adjacency relationship investigation (Hello packet) and the link state information exchange algorithm according to the present embodiment will be described.

First, in "OSPF", a representative router and a backup router are installed, adjacent information of each router is transmitted to the representative router, and the link state in the same area collected by the representative router is distributed to all routers. There is.

On the other hand, in the route establishing algorithm according to the present embodiment, GN (corresponding to the representative router)
1 collects the neighbor information, but does not distribute the neighbor information to each node. Therefore, LSD (Link
State Database) does not need to be synchronized. However,
It is necessary to synchronize the GNs. Also, GN1 is LS
Since it becomes the default for D storage, there is no need for an algorithm for dynamically determining the designated router. Further, the GN 1 is also different from the “OSPF” in that it manages resource information (for example, frequency, ch, code, etc.) because it is a wireless network.

As described above, in the communication system according to the present embodiment, at the time when a communication request is issued from MN2, GN1 has NN-DB held by GN1.
Route calculation is performed based on the adjacency information of No. 4 and the resource information of the resource management DB 5, and the calculation result is transmitted to all related nodes.

Next, with reference to the flowchart of FIG. 13, the sequence relating to the switching of the transmission mode will be described in detail. That is, when a communication request is issued by the MN2 (step S30), the GN1 determines the type of communication data (step S31). If it is control data, it is set to the control mode (step S32), and if it is data other than control, it is set to the relay mode (step S3).
3). With this setting, the transmission mode switching switch (not shown)
Are switched (step S34).

When transmitting / receiving data, the transmission mode is determined (step S35). Then, when the transmission mode is the control data, the control data is transmitted and received via the control mode wireless circuit (not shown) (step S3).
6, S37), if the transmission mode is the relay mode, data other than control is transmitted and received via the relay mode wireless circuit (not shown) (steps S38, S39).

<Second Embodiment> Next, the second embodiment of the present invention will be described.
A communication system and a communication method according to the embodiment will be described in detail. The second embodiment is based on the structure and operation of the above-described first embodiment and is further devised. That is, in the above-described first embodiment, when the MN2 exists outside the cell area of the GN1, the SRREQ packet cannot be transmitted, so that the connection request cannot be made. In the embodiment of the present invention, the existence of the own node can be registered in GN1 even when MN2 is outside the cell area of GN1,
Furthermore, communication is possible.

In the following, the same configurations as those in FIGS. 1 to 13 will be denoted by the same reference numerals, and the characteristic sequence according to the second embodiment will be mainly described.

First, the routing control by the communication system according to the second embodiment of the present invention will be described in detail with reference to the flowchart of FIG.

In this second embodiment, MN2 is GN
Even if it exists outside the cell area of 1, the other MN existing in the cell area of GN1 is searched for by multi-hop communication, and the other MN in the cell area of GN1 is connected to GN1 by single-hop communication. One of the features is that location registration and adjacency information are notified.

The routing control will be described in detail below based on such characteristics.

Now, when the MN2 becomes available (step S40), the MN2 connected to the network is connected.
First searches for GN1 in the control mode (single hop) (step S41). As described above with reference to FIG. 6, there are two methods for searching for the GN1, such as G advertisement and G request, but the duplicated description is omitted here.

In this way, when the MN2 searches the GN1 and confirms the existence of the GN1 (step S3), the MN2 investigates the neighbor information by the above-mentioned Hello protocol (see FIG. 7) (step S46). Incidentally, M
N2 can confirm the existence of GN1 because MN2 is G
This is the case when it belongs to the cell area of N1.

Subsequently, the MN 2 determines whether or not the adjacent node information has changed (step S47), and when the adjacent node information has changed, the process proceeds to step S49.

On the other hand, when there is no change in the adjacent node information, the MN 2 judges whether the update time has passed (step S48). When it is determined that the update time has not come, the process returns to step S46 and the same process as above is executed. On the other hand, if it is determined that the update time has come, the MN
2 updates the neighbor information to GN1 (step S
49).

After the above processing, if a communication request is made from MN2 to GN1 (step S50), GN1
Executes processing based on a route establishing algorithm, the details of which will be described later (step S51). In addition, this second
In the embodiment, the Hello interval and the update interval are stored in the MN in advance, and the adjacent information investigation and the update of the adjacent information are performed regularly.

On the other hand, in step S42, the MN
When 2 cannot find GN1 in the control mode (single hop), it determines whether or not there is route information to another MN located in the cell area of GN1 (step S43). Here, if there is the route information,
Proceeding to step S46, the same processing as above is performed.

On the other hand, if the route information does not exist, another MN existing in the cell area of GN1 is searched by flooding in the relay mode (multihop) (step S44). At this time, other MNs existing in the cell area of GN1 that have received the GN search packet due to flooding do not forward the packet to further MNs. That is, as shown in FIG. 17, when a GN search packet is transmitted by flooding from a MN in a cell area 100 (shaded area) where GN does not exist, for example, a further MN in the cell area 102 of GN1a transfers a packet. Is not performed, the boundary node neighborhood area 10
The situation in which the transfer is expanded more than 0 is prevented, the amount of control packets flowing out on the network is reduced, and the situation in which the network band is squeezed, the radio wave interference, and the packet collision problem are avoided.

Then, the GN1 judges whether or not the other MN existing in its own cell area can be found (step S45). And this step S
In 45, if the other MN can be found, the route is saved, and then the process proceeds to step S46, the same process as above is performed, and if the other MN cannot be found, the process proceeds to step S41. The process returns and the same process as above is performed.

Next, the route establishing algorithm executed in step S51 of FIG. 14 will be described in detail with reference to the flowchart of FIG.

Here, two types of transmission modes, a control mode (single hop) and a relay mode (multi-hop), a Hello protocol, and a route construction algorithm are mounted on each MN 2a, 2b, ...
A GN search function by multi-hop communication is implemented in a, 2b ..., And NN-DBs 3a, 3b in each MN 2a, 2b.
..., GN1 is assumed to be provided with NN-DB4 and resource management DB5.

In the following, the description will proceed with reference to FIGS. 16 and 17 as appropriate.

In FIG. 16, the small circles indicate MN, the small triangles indicate GN, and the circle drawn around the GN indicates the cell area of each GN. ing. In addition, in FIG. 17, the shaded area indicates the cell area 100 in which GN does not exist, and GN1
The cell area of a is indicated by reference numeral 102.

Now, a certain MN (Source Node and below, S
When a communication request is issued from N2a), it is determined whether or not the SN2a belongs to the cell area of GN1a (step S60). This step S60
In the case where it is determined that the SN2a does not belong to the cell area of the GN1a, the SN2a determines whether or not the route information to another MN belonging to the cell area of the GN1a is stored (step If it is determined that the route information is stored (S61), the SRREQ packet is transmitted to another MN by unicast according to the stored route (step S62). On the other hand, SN2a
When it is determined that the route information is not stored, the SRREQ packet is transmitted by flooding in the relay mode (multihop) (step S63),
It is determined whether another MN in the cell area of GN1a has received the SRREQ packet (step S6).
4).

In step S64, SN2a
Other MNs in the cell area of GN1a self (SN2
When it is determined that the SRREQ packet from a) has not been received, it is determined that the route establishment has failed, and this processing is ended. On the other hand, in this step S64, SN2
When a determines that another MN belonging to the cell area of GN1a has received the SRREQ packet from itself (SN2a), a stops the SRREQ packet transfer by the other MN that has received the SRREQ packet. , The other MN as the relay origin MN2b (step S6).
5). By stopping the packet transfer in this way,
As shown in FIG. 17, cell area 1 in which GN does not exist
00, the situation in which the transfer is expanded more than the boundary node neighboring area 100 is reduced, the amount of control packets flowing out on the network is reduced, and the situation that the network bandwidth is compressed, the radio wave interference, and the packet collision are reduced. I'm avoiding it.

The MN2b, which is the relay origin, is connected to the SN2a.
SRREQ sent in relay mode (multi-hop) from
GN1a packets in control mode (single hop)
To send a route request (step S6)
6).

Subsequently, the GN 1a sends the MN (Dest
It is determined whether or not an ination Node (hereinafter referred to as DN) is registered in the NN-DB 4 (step S67).
In this step S67, the DN is NN-DB4.
If it is determined that the route has not been registered, the process is terminated because the route establishment has failed.

On the other hand, in step S67, GN
When the 1a determines that the DN is registered in the NN-DB 4, the 1a checks whether the GN to which the DN belongs is adjacent (GN1b) or the same GN (GN1a) (step S68).

The GN1a is the GN to which the DN belongs.
However, if it is confirmed that they are adjacent or the same GN,
GN rather than the route (Gateway Route) through GN1a
In some cases, a route that does not go through 1a (Gatewayless Route) is more efficient, so Gateway Route and Gatewayless Rou
The source route (SR) and the route cost (RC) are calculated by both te, and the route with a small RC is selected (step S6).
9).

On the other hand, when it is confirmed in step S68 that the GN to which the DN belongs is not adjacent or the same GN, the GN1a calculates only the Gateway Route and determines the route (step S70). Note that, here, too, for example, the Dijkstra's shortest path algorithm is used for the route calculation of the MN-MN and the MN-GN, but the present invention is not limited to this.

When the GN1a determines the route in this way, the GN1a and the SN2a and all related nodes (SN2a-
The SRREP packet describing the used channel and the source route is transmitted to the source route between the DNs 2d). And
SN that received the SRREP packet from this GN1a
2a determines a channel to be used based on the information and creates a routing table (step S7).
1).

At this time, SN2a and DN2d are GN1.
a, if it is outside the cell area of GN1b, GN1
At the boundary node of the cell areas of a and 1b, the MN that belongs to the cell area is the relay origin MN2b and the relay origin M.
N2c.

Subsequently, GN1a has SN and DN of GN1.
a, GN1b is determined to belong to the cell area (step S72), and SN and DN are GN1a and GN1.
When it is determined that the user data belongs to the cell area of b (in this case, the SN and DN have a relationship with GN1a and GN1b such as SN2e and DN2f shown in FIG. 16), the user data is transmitted and received in the relay mode. . That is, various packets are unicast-communicated under the relay mode (multi-hop) based on the source route information included in the SRREP packet. Note that the existing wired algorithm (RIP, O
SPF etc.) is used.

On the other hand, in step S72, GN
1a judges that SN and DN do not belong to the cell area of GN1 (in this case, SN and DN are GN
1a, GN1b and SN2a, DN2d shown in FIG. 16), relay origin MN2b, relay origin MN
SR via unicast to SN2a and DN2d via 2c
A REP packet is transmitted (step S73).

Then, the GN1a judges whether or not the SRREP packet has reached the SN2a and DN2d (step S74). If it is judged that the SRREP packet has not arrived, the GN1a is the relay start point if the judgment is the first time. After transmitting the SRREP packet by flooding from MN2b of MN2b and MN2c of the relay origin to SN2a and DN2d (step S7).
5) The same judgment as in step S74 is performed.

Then, in step S74, G
When the N1a determines that the SRREP packet has not reached the SN2a and DN2d, if the determination is the second time or later, it is determined that the route establishment has failed, and the process ends. In step S74, G
When the N1a determines that the SRREP packet has reached the SN2a and DN2d, the N1a transmits / receives the user data in the relay mode. That is, various packets are
It is transmitted by unicast under relay mode based on the source route information contained in the packet. In steps S72 to S75, both SN and DN are GN1.
The subsequent processing was decided depending on whether or not it belongs to the cell area of a or 1b.
Even when it does not belong to the cell area of b, the problem can be solved by executing the processing of steps S73 to S75 for the one.

On the other hand, in step S60, SN
Is determined to belong to the cell area of GN1a (in this case, SN is GN1a and SN shown in FIG. 16).
2e), the route is constructed by transferring the SRREP packet according to the route notified from the GN 1a (step S66). After that, the same processing as that from step S67 onward is executed.

Next, referring to FIGS. 18 to 20, the second
Of GN1 in the communication system according to the embodiment of
-DB4, NN2a to 2g NN-DB3a to 3g
The stored contents of will be described in more detail. In FIG. 18, broken lines indicate the cell areas of the MNs 2a to 2g located at the centers, and solid lines indicate the GN1 cell area. Here, the MNs 2a to 2f are all located outside the cell area of the GN1, and the MN 2g is the relay origin MN.

Information shown in FIGS. 20A to 20G is stored in the NN-DBs 3a to 3g of the MNs 2a to 2g. That is, the adjacency information, whether the cell area of the GN of each neighbor MN is inside or outside, the route to the MN 2g of the relay origin of each neighbor MN, and each received power are stored in association with each other. For example, in FIG. 20B, MN2b
In the NN-DB 3b, the node ID of the MN 2f as the adjacency information, the fact that the MN 2f is outside the cell area of the GN 1 and the route 2f to the relay origin MN 2g of the MN 2f.
-2a-2d-2g and received power P2b-2f are stored.

Then, by the series of processing as described above, the MN-DBs 3a to 3g are processed by the MNs 2a to 2g.
Information is updated via the MN2g that is the relay origin, the GN1 sends the NN-DB as shown in FIG.
Update the contents of 4.

That is, in the NN-DB 4 of this GN1, for each of the MNs 2a to 2g, the GN1 of the MNs 2a to 2g.
The inside / outside of the cell area, the route to the MN2g of the relay origin of the MN2a to 2g, the node ID of the adjacent MN as the adjacent information, and the received powers are stored in association with each other. For example, as to the MN 2b, it can be seen that the contents of the NN-DB 3b are accumulated as a result of updating the information of FIG. 20 (b) described above.

<Effects of First and Second Embodiments> As described above, in the communication system and method according to the first and second embodiments of the present invention, the wired multi-hop communication is performed. The GN connected to the network is installed, and the centralized control type routing system by GN is adopted, which uses two transmission modes with different cell radii according to the communication application.

By regularly installing the GN in this way, the connection rate can be improved even when the node density is small, and the number of relay hops can be suppressed to a fixed number even if the network becomes large.

Further, by adopting a centralized control method utilizing two transmission modes, the amount of control packets can be quantified and S
It is also possible to shorten the route search time from N sending the SRREQ packet to receiving the SRREP packet.

In the second embodiment, in particular, one MN performs GN search by multihop,
It is possible to communicate with the GN from outside the cell area of the GN via another MN in the N cell area. And
At this time, other MNs existing in the GN cell area are
By not transferring the GN search packet and the route request packet from the MN outside the N cell area, it is possible to suppress the spread of the control packet on the network. In addition, the above-described algorithm that combines the routing control methods of the autonomous control type and the centralized control method can achieve a connection rate substantially equal to that in the cell area even outside the GN cell area.

The embodiment of the present invention has been described above, but the present invention is not limited to this, and various improvements and changes can be made without departing from the spirit of the present invention.

For example, the information stored as the adjacent information and the resource information is not limited to those described above, as a matter of course.

[0121]

As described in detail above, according to the present invention,
By adopting a centralized control method by GN that differentiates the communication conditions of control packets and actual data packets according to the transmission mode, the amount of control packets flowing out on the network is reduced and the network bandwidth is compressed. It is possible to provide a communication system and a communication method that avoid the problems of radio wave interference, radio wave interference, and packet collision. Furthermore, GN
It is possible to provide a communication system and a communication method that do not require autonomous route construction between the MNs by adopting the centralized control method according to the above and allowing the GN to grasp the adjacent information. Further, it is possible to provide a communication system and a communication method that allow a GN to grasp resource management information on a network and efficiently use limited network resources.

In particular, it is possible to provide a communication system and a communication method that enable the MN to communicate even if the MN is located outside the cell area of the GN, by registering the existence of the own node in the GN.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a communication system according to an embodiment of the present invention.

2A is a diagram showing a format of NN-DB3 of MN2, FIG. 2B is a diagram showing a format of NN-DB4 of GN1, and FIG. 2C is a diagram showing an adjacency relationship of MN2a-2f. .

3A is a diagram showing the contents of NN-DB3a of MN2a, FIG. 3B is a diagram showing the contents of NN-DB3b of MN2b, and FIG. 3C is a diagram showing the contents of NN-DB3c of MN2c; (d) is a diagram showing the contents of NN-DB3d of MN2d, (e) is a diagram showing the contents of NN-DB3e of MN2e, (f) is a diagram showing the contents of NN-DB3f of MN2f, (g) is a diagram of GN1. It is a figure which shows the content of NN-DB4.

4A is a diagram showing adjacency relations and communication relations of MNs 2a-2f, and FIG. 4B is a diagram showing contents of a resource management DB 5.

FIG. 5 is a flowchart of routing control by the communication system according to the present embodiment.

FIG. 6 is a diagram for explaining two methods for searching for GN1.

FIG. 7 is a flow chart for the Hello protocol.

8A is a diagram showing an adjacency relationship between MNs 2a-2f, and FIG. 8B is a diagram showing contents of NN-DB4.

9A is a diagram showing an adjacency relationship between MNs 2a-2f, and FIG. 9B is a diagram showing contents of NN-DB4.

10A is a diagram showing an adjacency relationship of MN2a-2f, FIG. 10B is a diagram showing the contents of NN-DB2a of MN2a, and FIG. 10C is a diagram showing the contents of NN-DB4. is there.

11A is a diagram showing an adjacency relationship of MN2a-2f, FIG. 11B is a diagram showing the contents of NN-DB2d of MN2d, and FIG. 11C is a diagram showing the contents of NN-DB2e of MN2e. It is a figure, (d) is a figure which shows the content of NN-DB2f of MN2f, (e) is a figure which shows the content of NN-DB4.

FIG. 12 is a flow chart for explaining in detail the route establishment algorithm executed in step S8 of FIG.

FIG. 13 is a flowchart illustrating in detail the flow of processing related to switching control modes.

FIG. 14 is a flowchart for detailed description of routing control by the communication system according to the second embodiment of the present invention.

FIG. 15 is a flowchart for explaining in detail the route establishing algorithm executed in step S51 of FIG.

FIG. 16 is a conceptual diagram for supplementing the explanation of the route establishment algorithm executed in step S51 of FIG.

FIG. 17 is also a model diagram of a network showing the relationship between the cell area 100 of the GN 1a and the boundary node neighboring area 100.

FIG. 18: MNs 2a to 2f, relay origin MN2g, G
It is a figure which shows the relationship of N1 and its cell area.

FIG. 19 is a diagram showing stored contents of NN-DB4 of GN1.

FIG. 20: NN-DBs 3a to 3g of MN2a to 2g
It is a figure which shows the memory content of.

[Explanation of symbols]

1 Gateway node (GN) 2 Mobile node (MN) 3 Adjacent node database (NN-DB) 4 Adjacent node database (NN-DB) 5 Resource Management Database (Resource Management DB)

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Claims (12)

[Claims] 1. A communication system in which at least a mobile station and a fixed station are communicable via a wireless network, comprising: a first database for storing adjacent information;
A plurality of mobile stations that periodically transmit the neighbor information accumulated in the database to the fixed station, a second database that stores the neighbor information of all the mobile stations existing within a predetermined range, and a third that stores the resource information. A fixed station that has a database and updates the stored contents of the second database with adjacent information transmitted from the mobile station, and one mobile station that does not belong to the cell area of the fixed station is the fixed station. When making a communication request to the mobile station, the one mobile station transmits communication request information to another mobile station belonging to the cell area of the fixed station by multi-hop communication, and the other mobile station transmits to the fixed station. Transferring the communication request information by single-hop communication, the fixed station calculates the communication route of the one mobile station while referring to the second and third databases based on the communication request information. Communication system to be. 2. When one mobile station that does not belong to the cell area of the fixed station cannot identify another mobile station that belongs to the cell area of the fixed station, the communication is performed by flooding by multi-hop communication. The communication system according to claim 1, further comprising transmitting request information. 3. When another mobile station belonging to the cell area of the fixed station receives the communication request information transmitted by flooding by the multi-hop communication, the other mobile station updates the communication request information. The communication system according to claim 2, further comprising: stopping transfer to another mobile station. 4. The fixed station, which has received a communication request from the one mobile station via another mobile station, when the station adjacent to the mobile station is itself or another fixed station adjacent to itself. , The communication route through the fixed station and the communication route not through the fixed station are both calculated, and the communication route is determined by selecting the communication route having a smaller route cost than the both, and the station adjacent to the mobile station is self or 4. The communication system according to claim 1, further comprising calculating only a communication route through the fixed station and determining the communication route when the fixed station is not another adjacent fixed station. 5. When performing communication between a destination mobile station and a source mobile station based on the determined communication route, the destination mobile station is one fixed station or adjacent to the fixed station. If it does not belong to the cell area of another fixed station, specify the mobile station of the relay origin of the mobile station of the transmission destination that belongs to the cell area, and communicate via the mobile station of the relay origin of the mobile station of the transmission destination. The communication system according to claim 4, further comprising: 6. The adjacency information includes at least node identification information related to other mobile stations existing in the adjoining range of one mobile station, and the resource information is information related to network resources and whether or not they are used. Further comprising at least identification information of the user.
The communication system according to any one of 1. 7. A plurality of mobile stations having at least a first database for storing adjacent information, a second database for storing adjacent information of all mobile stations existing within a predetermined range, and a third for storing resource information. In a communication method by a communication system in which a fixed station provided with a database is capable of communicating via a wireless network, the mobile station periodically transfers the adjacent information accumulated in the first database to the fixed station. The fixed station updates the stored content of the second database with the adjacent information transmitted from the mobile station, and one mobile station not belonging to the cell area of the fixed station communicates with the fixed station. When making a request, the one mobile station transmits communication request information by multi-hop communication to another mobile station belonging to the cell area of the fixed station, and the other mobile station. The mobile station transfers the communication request information to the fixed station by single-hop communication, and the fixed station refers to the second and third databases on the basis of the communication request information while referring to the one mobile station. A communication method characterized by calculating a communication route. 8. When one mobile station that does not belong to the cell area of the fixed station cannot identify another mobile station that belongs to the cell area of the fixed station, the communication is performed by flooding by multi-hop communication. The communication method according to claim 7, further comprising transmitting request information. 9. When another mobile station belonging to the cell area of the fixed station receives the communication request information transmitted by flooding by the multi-hop communication, the other mobile station updates the communication request information. The communication method according to claim 7, further comprising: stopping the transfer to the mobile station. 10. The fixed station which has received a communication request from the one mobile station via another mobile station, when the station adjacent to the mobile station is itself or another fixed station adjacent to itself. ,
The communication route is determined by calculating both the communication route passing through the fixed station and the communication route not passing through the fixed station, and selecting the communication route having a lower route cost than the both, and the station adjacent to the mobile station is the self or the self station. 10. The communication method according to claim 7, further comprising calculating only a communication route through the fixed station and determining the communication route when the fixed route is not adjacent to the other fixed station. 11. When performing communication between a destination mobile station and a source mobile station based on the determined communication route, the destination mobile station is one fixed station or adjacent to the fixed station. If it does not belong to the cell area of another fixed station, specify the mobile station of the relay origin of the mobile station of the transmission destination that belongs to the cell area, and communicate via the mobile station of the relay origin of the mobile station of the transmission destination. The communication method according to claim 10, further comprising: 12. The adjacency information includes at least node identification information related to other mobile stations existing in the adjacency range of one mobile station, and the resource information is information related to network resources and whether or not they are used. The communication method according to any one of claims 7 to 11, further comprising: at least user identification information.