1. An ad hoc network, comprising: a gateway connectable to a predetermined server via an external network; and a plurality of user nodes which constitute an ad hoc network 5 along with the gateway and each of which transmits data to the predetermined server via the gateway; wherein, among the user nodes, at least one user node having means for e s t a b l i s h i n g connection to the predetermined server via the external network can p a r t i c i p a t e (act) as a second gateway in the ad 10 hoc network; and wherein, based on a predetermined rule, the plurality of user nodes select any one of the gateway and/or the second gateway and transmit the data to the predetermined server.

2. The ad hoc network according to claim 1; wherein, if a connection environment to the external network of the at least one user node having the means for establishing connection to the predetermined server satisfies a predetermined 5 criterion, the at least one user node p a r t i c i p a t e as the second gateway in the ad hoc network.

3. The ad hoc network according to claim 1 or 2; wherein the at least one user node having the means for e s t a b l i s h i n g connection to the predetermined server comprises: a connection check unit checking a connection environment to 5 the external network of the at least one user node; a determination unit determining, when an operation for p a r t i c i p a t i o n of the at least one user node as the second gateway in the ad hoc network is performed, whether or not the at least one user node can p a r t i c i p a t e (act) as the second gateway, based on a result received 10 from the connection check unit; and an ad hoc routing unit performing, if the determination unit determines that the at least one user node can p a r t i c i p a t e as the second gateway, a gateway advertisement in the ad hoc network.

4. The ad hoc network according to any one of claims 1 to 3; 16 wherein data transmitted from the p l u r a l i t y of user nodes to the predetermined server is data measured by a predetermined measuring instrument.

5. The ad hoc network according to any one of claims 1 to 4, further comprising: a management server managing incentive points, based on at least one of a time period for which the at least one user node having 5 the means for establishing connection to the predetermined server has p a r t i c i p a t e d (acted) as the second gateway, a traffic amount forwarded by the at least one user node as the second gateway, and the number of nodes accommodated by the at least one user node.

6. A user node, to be connected to an ad hoc network constituted by a gateway connectable to a predetermined server via an external network and by a p l u r a l i t y of user nodes, each of which transmits data to the predetermined server via the gateway, the user node comprising: 5 means for establishing connection to the predetermined server via the external network; and means for advertising that the user node has p a r t i c i p a t e d (acted) as a second gateway in the ad hoc network; wherein the user node transmits data, received from another user 10 node that has selected the user node in place of the gateway, to the predetermined server.

7. The user node according to claim 6, further comprising: a connection check unit checking a connection environment to the external network; a determination unit determining, when an operation for 5 participation of the user node as the second gateway in the ad hoc network is performed, whether or not the user node can p a r t i c i p a t e as the second gateway based on a result received from the connection check unit; and an ad hoc routing unit performing, if the determination unit 10 determines that the user node can p a r t i c i p a t e as the second gateway, a gateway advertisement in the ad hoc network.

8. A management server, managing incentive points, based on at 17 least one of a time period for which the user node according to claim 6 or 7 has participated as the second gateway, a traffic amount forwarded by the user node as the second gateway, and the number of 5 nodes accommodated by the user node as the second gateway.

9. A data transmission method, comprising steps of: among the user nodes, comprised in an ad hoc network, at least one user node participating in the ad hoc network, the at least one user node having means for establishing connection to the predetermined 5 server via the external network as a second gateway in the ad hoc network; and causing another user node among the plurality of user nodes to select any one of the gateway and the second gateway and to transmit the data to the predetermined server, based on a predetermined rule; 10 wherein the ad hoc net work comprises a gateway connectable to a predetermined server via an external network and a plurality of user nodes, which constitute the ad hoc network along with the gateway and each of which transmits data to the predetermined server via the gateway.

10. A program, used in an ad hoc network comprising a gateway connectable to a predetermined server via an external network and a plurality of user nodes, which constitute the ad hoc network along with the gateway and each of which transmits data to the 5 predetermined server via the gateway, the program causing a computer loaded on at least one of the user nodes to perform processes of: checking a connection environment to the external network in response to a request from a user; 10 determining whether or not at least one user node can participate (act) as the second gateway based on a result of the check; and performing, if it is determined that the at least one user node can participate as the second gateway, a gateway advertisement in the 15 ad hoc network.

[DESCRIPTION]
[Title]
AD HOC NETWORK, USER NODE, MANAGEMENT SERVER,
COMMUNICATION METHOD, AND PROGRAM
[Field]
[0001]
(REFERENCE TO RELATED APPLICATION)
This a p p l i c a t i o n is based upon and claims the benefit of the priority of
Japanese patent application No. 2011-084510 filed on April 06, 2011,
10 the disclosure of which is incorporated herein in its entirety by
reference thereto.
The present invention relates to an ad hoc network, a user node, a
management server, a communication method, and a program. In
p a r t i c u l a r , it relates to: an ad hoc network including a gateway and a
15 plurality of communication nodes; a user node; a management server; a
communication method; and a program.
[Background]
[0002]
PTL 1 discloses an ad hoc network including: at least one
20 terminal having a wireless transceiver function of relaying a wireless
signal packet transmitted from another terminal; and at least two
gateways having a function of communicating with the terminal(s)' and
a function of e s t a b l i s h i n g connection to a public network.
[0003]
25 In addition, PTL 2 discloses an information collection system in
which a distance sensor is added to a node included in an ad hoc
network as described above. This information collection system
c o l l e c t s information about the distance between an aerial line that
extends between u t i l i t y poles and the ground.
30 [0004]
For example, the above ad hoc networks in PTL 1 and 2 can be
applied to smart meters. For example, smart meters have a function
of t r a n s m i t t i n g data read from e l e c t r i c i t y , gas, or water meters. Thus,
such smart meters are a t t r a c t i n g attention as a technique supporting a
2
next-generation power network called a smart grid.
[Citation List]
[Patent Literature]
[0005]
5 [PTL 1]
Japanese Patent Kokai Publication No. JP2005-79827A
[PTL 2]
Japanese Patent Kokai Publication No. JP2006-323440A
[Summary]
10 [Technical Problem]
[0006]
The disclosure of the above PTL is incorporated herein by
reference thereto. The following analysis has been given by the
present inventor. As disclosed in PTL 1, in the ad hoc network, since
15 a single gateway accommodates many communication nodes, band(s)
around the gateway is(are) narrowed, counted as a problem. In
addition, depending on the network topology, if the number of hops is
increased, a p l u r a l i t y of paths may not be ensured. Thus, redundant
path(s) that can be used in case of failure may not be ensured, counted
20 as a problem. In p a r t i c u l a r , in a l a r g e - s c a l e ad hoc network including
smart meters or the like, the network topology is r e s t r i c t e d by a large
number of nodes accommodated in a single gateway or by a positional
r e l a t i o n s h i p among houses. Thus, the above problems are considered
to be significant.
25 [0007]
PTL 1 aims to solve the above problems, by preparing a
p l u r a l i t y of gateways and allowing a terminal to select a gateway.
However, if the number of gateways is increased, installation and
maintenance costs are increased, counted as a problem.
30 [0008]
It is an object of the present invention to provide an ad hoc
network, a communication node, a communication method, and a
program, which can ensure the band(s) and redundant path(s) as
mentioned above without cost increase.
3
[Solution to Problem]
[0009]
According to a first aspect of the present invention, there is
provided an ad hoc network, comprising: a gateway connectable to a
5 predetermined server via an external network; and a p l u r a l i t y of user
nodes, which constitute an ad hoc network along with the gateway and
each of which transmits data to the predetermined server via the
gateway. Among the user nodes, at least one user node having means
for establishing connection to the predetermined server via the
10 external network can p a r t i c i p a t e (or act) as a second gateway in the ad
hoc network. User node(s) that has(have) selected the second
gateway in place of the gateway among the plurality of user nodes
transmits (or transmit) the data to the predetermined server via the
second gateway.
15 [0010]
According to a second aspect of the present invention, there is
provided a user node, to be connected to an ad hoc network constituted
by a gateway connectable to a predetermined server via an external
network and by a p l u r a l i t y of user nodes, each of which transmits data
20 to the predetermined server via the gateway. The user node
comprises: means for establishing connection to the predetermined
server via the external network; and means for advertising that the
user node has p a r t i c i p a t e d (or acted) as a second gateway in the ad hoc
network. The user node transmits data, received from another user
25 node that has selected the user node in place of the gateway, to the
predetermined server.
[0011]
According to a third aspect of the present invention, there is
provided a data transmission method, used in an ad hoc network
30 comprising a gateway connectable to a predetermined server via an
external network and a p l u r a l i t y of user nodes, which c o n s t i t u t e the ad
hoc network along with the gateway and each of which transmits data
to the predetermined server via the gateway. The data transmission
method comprises steps of: among the user nodes, at least one user
4
node having means for establishing connection to the predetermined
server via the external network participates (or acts) as a second
gateway in the ad hoc network; and causing another user node among
the p l u r a l i t y of user nodes to select any one of the gateway and/or the
5 second gateway and to transmit the data to the predetermined server,
based on a predetermined rule. This method is associated with
c e r t a in machines, that is, with the user nodes (communication nodes)
included in the ad hoc network.
[0012]
10 According to a fourth aspect of the present invention, there is
provided a program, used in an ad hoc network comprising a gateway
connectable to a predetermined server via an external network and a
p l u r a l i t y of user nodes, which constitute the ad hoc network along
with the gateway and transmits data to the predetermined server via
15 the gateway. The program causes a computer loaded on at least one
of the user nodes to perform processes of: checking a connection
environment to the external network in response to a request from a
user; determining whether or not the at least one user node can
p a r t i c i p a t e (or act) as the second gateway based on a result of the
20 check; and performing, if it is determined that the at least one user
node can p a r t i c i p a t e as the second gateway, a gateway advertisement
in the ad hoc network. This program can be recorded in a
computer-readable (non-transient) storage medium. Namely, the
present invention can be embodied as a computer program product.
25 [Advantageous Effects of Invention]
[0013]
According to the present invention, bandwidths and redundant
paths in an ad hoc network can be ensured without cost increase.
[Brief Description of Drawings]
30 [0014]
[Fig. 1]
Fig. 1 i l l u s t r a t e s an outline of an exemplary embodiment of the
present invention.
[Fig. 2]
5
Fig. 2 is a diagram that follows Fig. 1.
[Fig. 3]
Fig. 3 i l l u s t r a t e s a configuration of an ad hoc network according to a
first exemplary embodiment of the present invention.
5 [Fig. 4]
Fig. 4 is a block diagram i l l u s t r a t i n g a configuration of a user node
according to the first exemplary embodiment of the present invention.
[Fig- 5]
Fig. 5 is a flowchart i l l u s t r a t i n g an operation of a user node according
10 to the first exemplary embodiment of the present invention.
[Fig. 6]
Fig. 6 i l l u s t r a t e s a shortest path from a user node UN24 to a GW in
Fig. 3.
[Fig. 7]
15 Fig. 7 i l l u s t r a t e s a network configuration after user nodes UN13 and
UN23 in Fig. 3 are switched to GWs.
[Fig. 8]
Fig. 8 i l l u s t r a t e s a configuration of an ad hoc network according to a
second exemplary embodiment of the present invention.
20 [Fig. 9]
Fig. 9 i l l u s t r a t e s a table managed by a management server according to
the second exemplary embodiment of the present invention.
[Description of Embodiments]
[0015]
25 First, an outline of an exemplary embodiment of the present
invention will be described with reference to the drawings. In the
following outline, various components are denoted by reference
characters for the sake of convenience. Namely, the following
reference characters are merely used as examples to facilitate
30 understanding of the present invention. Thus, the present invention
is not limited to the i l l u s t r a t e d modes.
[0016]
In an exemplary embodiment of the present invention, as
i l l u s t r a t e d in Fig. 1, an ad hoc network can be realized by a
6
configuration including: a gateway (a GW 6 in Fig. 1) connectable to a
predetermined server (a collection server 7 in Fig. 1) via an external
network (the Internet in Fig. 1); and a p l u r a l i t y of user nodes (user
nodes 1 to 5 in Fig. 1), each of which transmits data to the
5 predetermined server via the gateway.
[0017]
Among the user nodes, a user node (the user node 1 in Fig. 1)
includes means (for example, an internet connection function via a
network connection terminal 8 in Fig. 1 or a broadband router) for
10 establishing connection to the predetermined server via the external
network.
[0018]
Based on a user's intention, this user node (the user node 1 in
Fig. 1) performs a gateway advertisement and notifies the other user
15 nodes in the ad hoc network of its own presence as a second gateway.
When notified, other user nodes belonging to the ad hoc network again
selects a gateway, in accordance with a corresponding predetermined
gateway selection rule.
[0019]
20 As a r e s u l t , as i l l u s t r a t e d in Fig. 2, user nodes (the user nodes 2
and 3 in Fig. 2), which have selected the second gateway (the user
node 1 in Fig. 1) in place of the gateway, transmit the data via the
second gateway (the user node 1 in Fig. 1).
[0020]
25 As described above, according to the present invention, a
second gateway can be configured by using a user node (the user node
1 in Fig. 1) prepared by a user and network connection means (a
network connection terminal 8 or a broadband router), without adding
a new gateway. Consequently, the number of nodes that are
30 accommodated (allocated) in a gateway (the GW 6 in Fig. 1) can be
reduced. In addition, as i l l u s t r a t e d in Fig. 2, since a total of two
gateways are deemed to have been installed, band(s) and redundant
path(s) can be ensured.
[0021]
7
[First exemplary embodiment]
Next, a first exemplary embodiment of the present invention will be
described in detail with reference to the drawings. Fig. 3 i l l u s t r a t es
a configuration of an ad hoc network according to a first exemplary
5 embodiment of the present invention. Fig. 3 i l l u s t r a t e s an ad hoc
network including user nodes UNI to UN24 and a gateway GW. In
Fig. 3, each solid line represents a path that is set from a user node
toward the gateway and each dashed line represents an a l t e r n a t i v e path
(by-pass route or redundant path).
10 [0022]
Each of the user nodes UNI to UN24 is a communication node
that a general customer user (which will hereinafter be referred to as
"a user") purchases or lends from a business operator or the like.
Each of the user nodes UNI to UN24 includes a wireless
15 communication function. By performing multi-hop forwarding from
user node to user node, each user node transmits data to the gateway
GW. Each of such user nodes may be a dedicated product including a
measuring instrument called a smart meter or may be a mobile wireless
router capable of exchanging data with an existing meter.
20 [0023]
Fig. 4 is a block diagram i l l u s t r a t i n g a configuration of a user
node that can p a r t i c i p a t e (act) as a gateway among the user nodes UNI
to UN24 (the following description will be made assuming that the
user nodes UN13 and UN23 can act as gateways). Fig. 4 i l l u s t r a t e s a
25 configuration including a network connection check unit 11, an
operation unit 12, a determination unit 13, an ad hoc routing unit 14,
and a data measurement unit 15.
[0024]
The network connection check unit 11 checks an Internet
30 connection environment of own user node in response to a request
from the determination unit 13 and transmits a reply to the
determination unit 13. For example, the Internet connection
environment signifies information about an Internet connection status
(a connection mode/a line type) and information about r e l i a b i l i t y of
8
Internet connection. When transmitting a reply, the network
connection check unit 11 may transmit a check result, such as by
t r a n s m i t t i n g a test packet or the like. In a simple way, the network
connection check unit 11 may read a s e t t i n g file or the like r e l a t i n g to
5 Internet connection of a home broadband router or a personal computer
connected thereto and may transmit the setting file or the like as a
replay.
[0025]
For example, the operation unit 12 includes a button for
10 receiving a u s e r ' s intention that the user wishes to p a r t i c i p a t e as a
second gateway (hereinafter, such node will be referred to as "a
volunteer GW," since the user voluntarily provides the Internet
connection environment of the node).
[0026]
15 When the determination unit 13 is notified by the operation unit
12 that the user wishes to participate as a volunteer GW, the
determination unit 13 causes the network connection check unit 11 to
make a query about the Internet connection environment of the user
node. When receiving a result of the query, the determination unit 13
20 determines whether or not the user node can p a r t i c i p a t e as a volunteer
GW based on the result of the query and notifies the ad-hoc routing
unit 14 of a result of the determination. For example, if the Internet
connection environment transmitted from the network connection
check unit 11 indicates a line capability insufficient to operate as a
25 volunteer GW or a security problem, the p a r t i c i p a t i o n (acting) as a
volunteer GW is rejected.
[0027]
If the determination unit 13 allows p a r t i c i p a t i on of the user
node as a volunteer GW, the ad-hoc routing unit 14 performs a gateway
30 advertisement to notify the ad hoc network of presence of user's own
user node (as a volunteer GW). This gateway advertisement includes
wireless link cost information or the like. If the determination unit
13 determines that the user node cannot be used as a volunteer GW or
if there is no user's i n t e n t i o n of using the user node as a volunteer GW,
9
the ad-hoc routing unit 14 forwards data measured by the data
measurement unit 15 as a communication node on the ad hoc network.
[0028]
If the ad-hoc routing unit 14 receives a gateway advertisement
5 from a volunteer GW on the ad hoc network, the ad-hoc routing unit 14
selects a low-cost gateway from the gateways GWs including this
volunteer GW. Other than such cost-based method, a gateway can be
selected by using a band information notification message disclosed in
PTL 1, for example.
10 [0029]
The data measurement unit 15 is means for measuring data of
measuring instrument(s) and outputting the measured meter data to the
ad-hoc routing unit 14. The data measurement unit 15 does not
n e c e s s a r i l y measure meter data. For example, data about electricity,
15 water, or gas usage measured by another measuring instrument(s) can
be included.
[0030]
The present exemplary embodiment will be described assuming
that the user nodes UN13 and UN23 include the above configuration
20 and the other user nodes include only the ad-hoc routing unit 14 and
the data measurement unit 15. Of course, all the nodes may include
the above configuration. In such case, all users can be given
opportunity to switch the respective nodes to volunteer GWs.
[0031]
25 The network connection check unit 11 and the determination
unit 13 in the user node i l l u s t r a t e d in Fig. 4 can be realized by a
computer program causing a computer mounted on the user node to use
its hardware and to perform processing corresponding to the above
network connection check unit 11 and determination unit 13.
30 [0032]
Next, an operation of the present exemplary embodiment will be
described in detail with reference to the drawings. Fig. 5 is a
flowchart i l l u s t r a t i n g an operation of a user node according to the
present exemplary embodiment.
10
[0033]
In Fig. 5, first, if it is determined that a user has indicated
his/her intention to participate as a volunteer GW (an operation of
switching a user node to a GW) (Yes in step S001), the determination
5 unit 13 queries the network connection check unit 11 about whether
this user node has an Internet connection environment (step S002).
[0034]
If, as a result of the query, the determination unit 13 receives a
reply that the user node has an Internet connection environment (Yes
10 in step S002), the determination unit 13 determines whether the
Internet connection environment satisfies a predetermined criterion
(step S003).
[0035]
If, as a result of the determination, the determination unit 13
15 determines that the Internet connection environment of the user node
s a t i s f i e s a predetermined criterion (Yes in step S003), the
determination unit 13 notifies the ad-hoc routing unit 14 to that effect.
When notified, the ad-hoc routing unit 14 performs a gateway
advertisement in the ad hoc network (step S004).
20 [0036]
If the determination unit 13 determines "No" in any of the above
steps S001 to S003, no gateway advertisement is performed.
[0037]
Fig. 6 i l l u s t r a t e s a configuration of an ad hoc network before
25 the user nodes UN13 and UN23 are switched to volunteer GWs. In
Fig. 6, the gateway GW accommodates 24 user nodes of the user nodes
UNI to UN24. The number of hops of the shortest path from the user
node UN24 to the gateway GW amounts to 11. In addition, only one
path exists between the user nodes UN7 and UN9 and between the user
30 nodes UN17 and UN19. Namely, there is no a l t e r n a t i v e path (by-pass
or redundant path) for the user nodes UN9 and UN19.
[0038]
Fig. 7 i l l u s t r a t e s a configuration of the ad hoc network after the
flow i l l u s t r a t e d in Fig. 5 is performed and the user nodes UN13 and
11
UN23 are switched to act as volunteer GWs. In Fig. 7, the number of
user nodes accommodated by each of the gateways, including the
volunteer GWs, is leveled to 8. In addition, the number of hops of
the shortest path from the user node UN24 to the user node UN23,
5 which is the volunteer GW closest to the user node UN24, is 1. In
addition, an alternative path (redundant path) has been provided
between the user nodes UN9 and UN19.
[0039]
Thus, according to the present exemplary embodiment, without
10 making additional infrastructure investments, the number of user
nodes that can be accommodated by (allocated to) each gateway can be
reduced, and the use efficiency of the ad hoc network can be
improved.
[0040]
15 In addition, according to the present exemplary embodiment,
since the number of hops from a user node to a gateway can be reduced,
the possibility of failure in data transmission/reception can be
reduced.
[0041]
20 In addition, according to the present exemplary embodiment,
since the number of choices for a path from a user node to the Internet
is increased, even if failure is caused, connection to the Internet can
be ensured. For example, even if a failure is caused in the gateway
GW in Fig. 7, by using an a l t e r n a t i v e path (by-pass route) between the
25 user nodes UN7 and UN9, the user nodes UNI to UN7 can transmit
data via the user node UN13.
[0042]
[Second exemplary embodiment]
Next, a second exemplary embodiment of the present invention will be
30 described in detail with reference to the drawings. In the second
exemplary embodiment, an incentive is provided for taking
p a r t i c i p a t i o n as a volunteer GW as described above.
[0043]
Fig. 8 i l l u s t r a t e s a configuration of an ad hoc network according
12
to the second exemplary embodiment of the present invention. This
configuration in Fig. 8 differs from that i l l u s t r a t e d in Fig. 1 in that, a
management server 9 is arranged on the Internet. Since other basic
components are the same as those that are i l l u s t r a t e d in Fig. 1 and that
5 are described in the first exemplary embodiment, the following
d e s c r i p t i o n will be made with a focus on differences.
[0044]
The management server 9 in Fig. 8 is a server that monitors
each of the user nodes and checks those used as volunteer GWs. In
10 addition, based on a band or time provided by a user node as a
volunteer GW, the management server 9 provides the user with points
(incentive points) and manages these points.
[0045]
Fig. 9 i l l u s t r a t e s a table managed by the management server 9
15 according to the present exemplary embodiment. As i l l u s t r a t e d in Fig.
9, the user nodes UN13 and UN23 have participated (acted) as
volunteer GWs for certain time periods, respectively. Thus, these
nodes have been provided with points according to the respective time
periods. In contrast, the other user nodes have not acted as volunteer
20 GWs. Thus, these nodes have not been provided with points.
[0046]
By providing a discount corresponding to the points, for
example, on electricity, gas, or water charges determined based on
measured data collected by each of user nodes, it is possible to give
25 an incentive to p a r t i c i p a t e as volunteer GWs. Of course, other than
such discount on the e l e c t r i c i t y , gas, water charges, the points may be
exchanged with goods or with points in another point system.
[0047]
In Fig. 9, points are given according to the time periods for
30 which the nodes have p a r t i c i p a t e d as volunteer GWs. However, for
example, points may be given and managed according to the amount of
traffic that each volunteer GW has forwarded or the number of nodes
each volunteer GW has accommodated (allocated) or according to a
combination of the amount and the number.
13
[0048]
According to the second exemplary embodiment of the present
invention, since an increase in the number of user nodes that
p a r t i c i p a t e as volunteer GWs is expected, the band(s) can be used
5 more efficiently than those in the above first exemplary embodiment.
In addition, users can acquire rewards by using resources (network
connection environments) in an idle condition.
[0049]
While preferred exemplary embodiments of the present invention
10 have thus been described, the present invention is not limited thereto.
Further variations, s u b s t i t u t i o n s , or adjustments can be made without
departing from the basic technical concept of the present invention.
For example, the user node numbers and the topology configurations
used in the above exemplary embodiments are examples to facilitate
15 understanding of the present invention. Various changes may be made
to these numbers and configurations. In particular, the components
and parts described in each aspect, each exemplary embodiment, each
example, and each drawing can be selected, combined, or changed,
without departing from the basic technical concept of the present
20 invention.
[0050]
In addition, each of the above exemplary embodiments has been
described assuming that each user node is connected to the Internet via
a network connection terminal 8, a broadband router, or the like.
25 However, alternatively, each user node may be connected to the
network via another device or may include a network connection
f u n c t i o n.
[Reference Signs List]
[0051]
30 1 to 5 user node
6 gateway (GW)
7 collection server
8 network connection terminal
9 management server
14
1 1 network connection check unit
1 2 operation unit
13 determination unit
14 ad hoc routing unit
15 data measurement unit
UNI to UN24 user node
GW gateway

15
CLAIMS:
1. An ad hoc network, comprising:
a gateway connectable to a predetermined server via an external
network; and
a plurality of user nodes which constitute an ad hoc network
5 along with the gateway and each of which transmits data to the
predetermined server via the gateway;
wherein, among the user nodes, at least one user node having
means for e s t a b l i s h i n g connection to the predetermined server via the
external network can p a r t i c i p a t e (act) as a second gateway in the ad
10 hoc network; and
wherein, based on a predetermined rule, the plurality of user
nodes select any one of the gateway and/or the second gateway and
transmit the data to the predetermined server.
2. The ad hoc network according to claim 1;
wherein, if a connection environment to the external network of
the at least one user node having the means for establishing
connection to the predetermined server satisfies a predetermined
5 criterion, the at least one user node p a r t i c i p a t e as the second gateway
in the ad hoc network.
3. The ad hoc network according to claim 1 or 2;
wherein the at least one user node having the means for
e s t a b l i s h i n g connection to the predetermined server comprises:
a connection check unit checking a connection environment to
5 the external network of the at least one user node;
a determination unit determining, when an operation for
p a r t i c i p a t i o n of the at least one user node as the second gateway in the
ad hoc network is performed, whether or not the at least one user node
can p a r t i c i p a t e (act) as the second gateway, based on a result received
10 from the connection check unit; and
an ad hoc routing unit performing, if the determination unit
determines that the at least one user node can p a r t i c i p a t e as the second
gateway, a gateway advertisement in the ad hoc network.
4. The ad hoc network according to any one of claims 1 to 3;
16
wherein data transmitted from the p l u r a l i t y of user nodes to the
predetermined server is data measured by a predetermined measuring
instrument.
5. The ad hoc network according to any one of claims 1 to 4,
further comprising:
a management server managing incentive points, based on at
least one of a time period for which the at least one user node having
5 the means for establishing connection to the predetermined server has
p a r t i c i p a t e d (acted) as the second gateway, a traffic amount forwarded
by the at least one user node as the second gateway, and the number of
nodes accommodated by the at least one user node.
6. A user node, to be connected to an ad hoc network constituted
by a gateway connectable to a predetermined server via an external
network and by a p l u r a l i t y of user nodes, each of which transmits data
to the predetermined server via the gateway, the user node comprising:
5 means for establishing connection to the predetermined server
via the external network; and
means for advertising that the user node has p a r t i c i p a t e d (acted)
as a second gateway in the ad hoc network;
wherein the user node transmits data, received from another user
10 node that has selected the user node in place of the gateway, to the
predetermined server.
7. The user node according to claim 6, further comprising:
a connection check unit checking a connection environment to
the external network;
a determination unit determining, when an operation for
5 participation of the user node as the second gateway in the ad hoc
network is performed, whether or not the user node can p a r t i c i p a t e as
the second gateway based on a result received from the connection
check unit; and
an ad hoc routing unit performing, if the determination unit
10 determines that the user node can p a r t i c i p a t e as the second gateway, a
gateway advertisement in the ad hoc network.
8. A management server, managing incentive points, based on at
17
least one of a time period for which the user node according to claim 6
or 7 has participated as the second gateway, a traffic amount
forwarded by the user node as the second gateway, and the number of
5 nodes accommodated by the user node as the second gateway.
9. A data transmission method, comprising steps of:
among the user nodes, comprised in an ad hoc network, at least
one user node participating in the ad hoc network, the at least one user
node having means for establishing connection to the predetermined
5 server via the external network as a second gateway in the ad hoc
network; and
causing another user node among the plurality of user nodes to
select any one of the gateway and the second gateway and to transmit
the data to the predetermined server, based on a predetermined rule;
10 wherein the ad hoc net work comprises a gateway connectable to
a predetermined server via an external network and a plurality of user
nodes, which constitute the ad hoc network along with the gateway and
each of which transmits data to the predetermined server via the
gateway.
10. A program, used in an ad hoc network comprising a gateway
connectable to a predetermined server via an external network and a
plurality of user nodes, which constitute the ad hoc network along
with the gateway and each of which transmits data to the
5 predetermined server via the gateway,
the program causing a computer loaded on at least one of the
user nodes to perform processes of:
checking a connection environment to the external network in
response to a request from a user;
10 determining whether or not at least one user node can
participate (act) as the second gateway based on a result of the check;
and
performing, if it is determined that the at least one user node
can participate as the second gateway, a gateway advertisement in the
15 ad hoc network.