Description
Title of Invention
INFORMATION PROCESSING DEVICE AND INFORMATION PROCESSING
METHOD
Technical Field
[0001]
The present technology relates to an information processing device.
10 Particularly, the technology relates to an information processing device and an
information processing method for dealing with information regarding wireless
communication.
Background Alt
15 [0002]
In the related art, there are wireless communication technologies for
exchanging various kinds of data using wireless communication. For example, a
communication method for making an autonomous connection with a nearby
information processing device (for example, ad hoc communication or an ad hoc
20 network) has been proposed (for example, see Patent Literature 1).
25
30
Citation List
Non-Patent Literature
[0003]
Patent Literature 1: JP 2009-239385A
Summary of Invention
Technical Problem
[0004]
According to the teclmology of the related art mentioned above, various
kinds of data can be exchanged between two information processing devices using
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wireless communication, without connection on a wired network. In addition, on
such a network, each information processing device can perform communication
with a nearby information processing device, without depending on a master station
such as a control device. Fmihermore, on an ad hoc network, when a new
5 infmmation processing device appears nearby, this new information processing
device can also freely participate in the network. Thus, network coverage can be
widened in accordance with an increase of nearby information processing devices.
[0005]
In addition, on top of such an autonomous connection with a nearby
10 information processing device, each information processing device can also transfer
information to be exchanged with another information processing device in a bucket
brigade manner (which is so-called multi-hop relay). In addition, a network using
multi-hop is generally known as a mesh network.
[0006]
15 As described above, on an ad hoc network or a mesh network, it is possible
to freely communicate with nearby information processing devices. In addition, the
network can be expanded while connections with information processing devices
around are being made. In this case, it is important to appropriately generate and
manage a communication path between the plurality of information processing
20 devices.
25
[0007]
The present technology takes the above circumstances into consideration,
and aims to properly generate and manage a communication path between a plurality
of information processing devices.
Solution to Problem
[0008]
The present teclmology has been made in order to solve the abovementioned
issues. According to a first aspect of the present teclmology, there is
30 provided an information processing device, an information processing method, and a
program for causing a computer to execute the method, the information processing
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device including: a communication unit configured to pmform exchange of a signal
for generation or updating of a multi-hop communication path using wireless
communication with another information processing device; and a control unit
configured to perform control to update path information regarding the
5 communication path set through the exchange of the signal before the path
information is destroyed. Accordingly, an effect of performing updating of the path
information regarding the communication path set through the exchange of the signal
before the path information is destroyed is exhibited.
10
[0009]
According to the first aspect, the control unit may decide an effective time
for specifying a time at which the path information is destroyed and decides an
updating time for specifying a time during which the path information is updated to
be a time shorter than the effective time based on expiration time information
included in the signal. Accordingly, an effect of deciding the effective time and
15 deciding the updating time as a time shorter than the effective time is exhibited.
[0010]
According to the first aspect, the control unit may change the updating time
based on a position of the information processing device on the communication path.
Accordingly, an effect of changing the updating time based on the position of the
20 information processing device on the communication path is exhibited.
[OOll]
According to the first aspect, when the information processing device is an
information processing device located at an end of the communication path, the
control unit may set the updating time to be shatter than an updating time of another
25 information processing device on the communication path. Accordingly, an effect
of setting the updating time to be shorter than that of another information processing
device on the communication path when the information processing device is an
information processing device located at the end of the communication path is
exhibited.
30 [0012]
According to the first aspect, the control unit may set the updating time to
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be the shmtest when the infonnation processing device is the information processing
device located at the end and the infmmation processing device is a transmission
source station which has transmitted the signal first, and set the updating time to be
the second shmtest when the information processing device is the information
5 processing device located at the end and the information processing device is a
destination station which is a destination of the signal. Accordingly, an effect of
setting the updating time to be the shortest when the information processing device is
the transmission source station and setting the updating time to be the second shmtest
when the infmmation processing device is the destination station is exhibited.
10 [0013]
According to the first aspect, the control unit may change the effective time
based on the number of relay stations that are information processing devices
relaying the signal on the communication path. Accordingly, an effect of changing
the effective time based on the number of relay stations is exhibited.
15 [0014]
According to the first aspect, when the same communication path is
consecutively selected as a communication path updated through the exchange of the
signal, or when a rate of selection of the same communication path is higher than a
predetermined value, the control unit may lengthen the effective time and the
20 updating time. Accordingly, an effect of lengthening the effective time and the
updating time when the same communication path is consecutively selected or when
a rate of selection of the same communication path is higher than the predetermined
value is exhibited.
25
[0015]
According to the first aspect, the control unit may lengthen the effective
time and the updating time when an electric field intensity of an information
processing device that is designated as a next transmission destination on the
communication path is higher than a tlu·eshold value, and shorten the effective time
and the updating time when the electric field intensity of the information processing
30 device that is designated as the next transmission destination is lower than the
threshold value. Accordingly, effects of lengthening the effective time and the
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updating time when the electric field intensity of the information processing device
that is designated as a next transmission destination is higher than the threshold value,
and shortening the effective time and the updating time when the electric field
intensity of the information processing device that is designated as the next
5 transmission destination is lower than the tlu-eshold value are exhibited.
[0016]
According to the first aspect, when the information processing device is
moving, the control unit may shmten the effective time and the updating time.
Accordingly, an effect of shortening the effective time and the updating time when
10 the information processing device is moving is exhibited.
[0017]
According to the first aspect, when an electric field intensity of an
information processing device that is not designated as a next transmission
destination on the communication path is higher than a threshold value, the control
15 unit may shorten the effective time and the updating time. Accordingly, an effect of
shortening the effective time and the updating time when the electric field intensity
of the information processing device that is not designated as a next transmission
destination on the communication path is higher than the threshold value is exhibited.
[0018]
20 According to the first aspect, when there is an information processmg
device with the number of packet losses greater than a threshold value among
infonnation processing devices that are designated as next transmission destinations
on the communication path, the control unit may transmit a signal for updating the
communication path to another information processing device on the collllllunication
25 path which includes the information processing device. Accordingly, an effect of
transmitting the signal for updating the communication path to the other information
processing device on the communication path which includes the foregoing
information processing device when there is the infmmation processing device with
the number of packet losses greater than the tlu-eshold value among the information
30 processing devices that are designated as next transmission destinations on the
communication path is exhibited.
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[0019]
According to the first aspect, when there is an information processmg
device which has established a new link to the foregoing information processing
device, the control unit may transmit a signal for updating the communication path to
5 another information processing device on the communication path which includes
the information processing device. Accordingly, an effect of transmitting the signal
for updating the communication path to the other information processing device on
the communication path which includes the foregoing information processing device
when there is the information processing device which has established a new link to
10 the foregoing information processing device is exhibited.
[0020]
According to the first aspect, the control unit may transmit a signal for
updating the communication path by setting a random delay time. Accordingly, an
effect of transmitting the signal for updating the communication path by setting a
15 random delay time is exhibited.
[0021]
According to the first aspect, when a link with an infonnation processing
device that is designated as a next transmission destination on the communication
path is disconnected, the control unit may transmit a signal for updating the
20 communication path to another information processing device on the communication
path which includes the inf01mation processing device. Accordingly, an effect of
transmitting a signal for updating the communication path to the other information
processing device on the communication path which includes the foregoing
information processing device when the link with the information processing device
25 that is designated as a next transmission destination is discom1ected is exhibited.
Advantageous Effects oflnvention
[0022]
According to the present technology, the excellent effect of appropriately
30 generating and managing communication paths between a plurality of information
processing devices can be exhibited. It should be noted that the effect described
-~ /
>;f/
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here is not necessarily limitative, and any effect described in the present disclosure
may be exhibited.
Brief Description of Drawings
5 [0023]
[FIG. 1] FIG. 1 is a diagram showing a system configuration example of a
communication system 200 according to a first embodiment of the present
technology.
[FIG. 2] FIG. 2 is a block diagram showing an intemal configuration example of an
10 infonnation processing device I 00 according to the first embodiment of the present
teclmology.
[FIG. 3] FIG. 3 is a diagram showing an example of a signal format of a packet
exchanged between information processing devices which constitute the
communication system 200 according to the first embodiment of the present
15 technology.
[FIG. 4] FIG. 4 is a diagram showing examples of signal formats of a management
packet exchanged between the information processing devices which constitute the
communication system 200 according to the first embodiment of the present
technology.
20 [FIG. 5] FIG. 5 is a diagram showing an example of the content of the signal format
of the management packet exchanged between the information processing devices
which constitute the communication system 200 according to the first embodiment of
the present technology.
[FIG. 6] FIG. 6 is a diagram showing an example of the content of the signal fonnat
25 of the management packet exchanged between the information processing devices
which constitute the communication system 200 according to the first embodiment of
the present technology.
[FIG. 7] FIG. 7 is a diagram showing an example of the content of the signal format
of the management packet exchanged between the information processing devices
30 which constitute the conununication system 200 according to the first embodiment of
the present technology.
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[FIG. 8] FIG. 8 is a diagram schematically showing an example of a mesh path table
(mesh path table 340) retained by each of information processing devices which
constitute the communication system 200 according to the first embodiment of the
present technology.
5 [FIG. 9] FIG. 9 is a diagram showing a generation example of a mesh path retained
by each of the information processing devices which constitute the communication
system 200 according to the first embodiment of the present technology.
[FIG. I 0] FIG. I 0 is a diagram showing a generation example of a mesh path retained
by each of the information processing devices which constitute the communication
10 system 200 according to the first embodiment of the present teclmology.
[FIG. I I] FIG. I I is a diagram schematically showing another example of the mesh
path table (mesh path table 350) retained by each of the information processing
devices which constitute the conununication system 200 according to the first
embodiment of the present technology.
15 [FIG. 12] FIG. 12 is a diagram showing generation and updating examples of the
mesh path table 350 retained by each of the information processing devices which
constitute the communication system 200 according to the first embodiment of the
present technology.
[FIG. 13] FIG. 13 is a diagram showing generation and updating examples of the
20 mesh path table 350 retained by each of the information processing devices which
constitute the collllllunication system 200 according to the first embodiment of the
present technology.
[FIG. 14] FIG. 14 is a diagram showing generation and updating examples of the
mesh path table 350 retained by each of the information processing devices which
25 constitute the communication system 200 according to the first embodiment of the
present technology.
[FIG. 15] FIG. 15 is a diagram showing generation and updating examples of the
mesh path table 350 retained by each of the information processing devices which
constitute the communication system 200 according to the first embodiment of the
30 present technology.
[FIG. I 6] FIG. I 6 is a diagram showing generation and updating examples of the
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mesh path table 350 retained by each of the information processing devices which
constitute the communication system 200 according to the first embodiment of the
present technology.
[FIG. 17] FIG. 17 is a diagram schematically showing still another example of the
5 mesh path table (mesh path table 360) retained by each of the information processing
devices which constitute the communication system 200 according to the first
embodiment of the present technology.
[FIG. 18] FIG. 18 is a diagram showing generation and updating examples of the
mesh path table 350 retained by each of the information processing devices which
10 constitute the communication system 200 according to the first embodiment of the
present technology.
[FIG. 19] FIG. 19 is a flowchatt showing an example of the procedure of signal
processing by the information processing device 100 according to the first
embodiment of the present technology.
15 [FIG. 20] FIG. 20 is a flowchatt showing an example of the procedure of signal
processing by the information processing device 100 according to the first
embodiment of the present technology.
[FIG. 21] FIG. 21 is a flowchart showing an example of the procedure of signal
processing by the information processing device 100 according to the first
20 embodiment of the present technology.
[FIG. 22] FIG. 22 is a flowchmt showing an example of the procedure of signal
processing by the information processing device 1 00 according to the first
embodiment of the present technology.
[FIG. 23] FIG. 23 is a flowchatt showing an example of the procedure of signal
25 processing by the information processing device 100 according to the first
embodiment of the present teclmology.
[FIG. 24] FIG. 24 is a flowchart showing an example of the procedure of signal
processing by the information processing device 1 00 according to the first
embodiment of the present technology.
30 [FIG. 25] FIG. 25 is a flowchatt showing an example of the procedure of signal
processing by the infmmation processing device 100 according to a second
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embodiment of the present technology.
[FIG. 26] FIG. 26 is a flowchart showing an example of the procedure of signal
processing by the information processing device I 00 according to the second
embodiment of the present teclmology.
5 [FIG. 27] FIG. 27 is a flowchmi showing an example of the procedure of signal
processing by the information processing device 100 according to the second
embodiment of the present technology.
[FIG. 28] FIG. 28 is a diagram schematically showing still another example of the
mesh path table (mesh path table 370) retained by each of the information processing
10 devices which constitute the communication system 200 according to the second
embodiment of the present teclmology.
[FIG. 29] FIG. 29 is a flowchmi showing an example of the procedure of signal
processing by the information processing device 1 00 according to the second
embodiment of the present technology.
15 [FIG. 30] FIG. 30 is diagram schematically showing a computation process of a
metric value by the information processing device 100 according to the second
embodiment of the present technology.
[FIG. 31] FIG. 31 is a diagram schematically showing path selection of the
communication system 200 according to the second embodiment of the present
20 technology.
[FIG. 32] FIG. 32 is a flowchart showing an example of the procedure of signal
processing by the information processing device 100 according to the second
embodiment of the present technology.
[FIG. 33] FIG. 33 is a diagram schematically showing still another example of the
25 mesh path table (mesh path table 380) retained by each of the information processing
devices which constitute the communication system 200 according to the second
embodiment of the present technology.
[FIG. 34] FIG. 34 is a flowchart showing an example of the procedure of signal
processing by the information processing device I 00 according to the second
30 embodiment of the present technology.
[FIG. 35] FIG. 35 is a diagram showing four access categories (ACs) of IEEE
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802.11e-Enhanced Distributed Channel Access (EDCA).
[FIG. 36] FIG. 36 is a block diagram showing an example of a schematic
configuration of a smartphone.
[FIG. 37] FIG. 37 is a block diagram showing an example of a schematic
5 configuration of a car navigation device.
Description of Embodiments
[0024]
10 Hereinafter, embodiments for implementing the present technology (which
will be referred to hereinafter as embodiments) will be described. Description will
be provided in the following order.
1. First embodiment (Example in which an expiration time and updating
expiration time of a path metric are set)
15 2. Second embodiment (Example in which a path metric value is changed)
3. Application example
20
[0025]
<1. First embodiment>
[Configuration example of a communication system]
FIG. 1 is a diagram showing a system configuration example of a
communication system 200 according to a first embodiment of the present
technology.
[0026]
The communication system 200 includes a plurality of information
25 processing devices (an information processing device I 00, an infmmation processing
device 210, an information processing device 220, an information processing device
230, and an information processing device 240). Each of the information
processing devices constituting the communication system 200 is, for example, a
portable type information processing device or a fixed type information processing
30 device with a wireless conmumication function. It should be noted that portable
type information processing devices include wireless communication devices, for
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example, smartphones, mobile telephones, tablet terminals, and fixed type
information processing devices include information processing devices such as
printers, personal computers, and the like.
[0027]
5 In FIG. 1 rectangles representing the information processing devices are
labeled with reference symbols (A to E) for identifYing the respective information
processing devices. In other words, the rectangle representing the information
processing device 100 IS labeled "A," the rectangle representing the information
processing device 210 IS labeled "B," the rectangle representing the information
10 processing device 220 is labeled "C," the rectangle representing the information
processing device 230 is labeled "D," and the rectangle representing the information
processing device 240 is labeled "E." In addition, the reference symbols A toE are
used to display the content of signals exchanged between the information processing
devices as shown in FIGS. 9, 10, and the like.
15 [0028]
'
In addition, FIG. I shows conmmnication paths between the information
processing device 100 and the information processing devices 210, 220, and 230
using dotted lines 251, 253, and 254. In addition, communication paths between the
other information processing devices are likewise indicated using dotted lines 252
20 and 255 to 257.
[0029]
Here, as a communication method for autonomously connecting with a
nearby infmmation processing device, ad hoc communication, an ad hoc network,
and the like are known. On such a network, each information processing device can
25 pe1form communication with a nearby information processing device without
depending on a master station (for example, a control device). Thus, in this
embodiment of the present technology, an ad hoc network will be exemplified as a
col1111nmication method for autonomously connecting with a nearby information
processing device
30 [0030]
When a new nearby information processing device is added on an ad hoc
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network, this new information processing device can fi·eely participate in the network.
For example, a case in which, among the information processing devices shown in
FIG. I, only the information processing device 100, the information processing
device 210, the information processing device 220 first pmticipate in the ad hoc
5 network is assumed. In this case, the informat'ion processing device 230 and the
information processing device 240 are assumed to be added in order. In this case,
as the number of the information processing devices (nearby information processing
devices) increases, coverage of the network can be widened. That is, according to
the addition of the information processing device 230 and the information processing
10 device 240 in order, coverage of the network can be widened.
[0031]
Here, on top of autonomous connection with a nearby infonnation
processing device, each information processing device can also transfer information
to be exchanged with another information processing device in a bucket brigade
15 manner.
[0032]
It is assumed that, for example, the information processing device 100 can
directly communicate with each of the information processing devices 210, 220, and
230, but is not able to directly communicate with the information processing device
20 240 for a reason such as radio waves failing to reach the device.
[0033]
When direct communication is not possible as described above, the
information processing devices which can directly communicate with the information
processing device 100 (the information processing devices 210, 220, and 230) can
25 transfer data of the information processing device 100 to the information processing
device 240. Thus, such transfer of data enables the information processing device
100 and the information processing device 240 which does not directly communicate
with the information processing device 100 to exchange information via any of the
information processing devices 210, 220, and 230.
30 [0034]
This method of pe1fonning data transfer between devices (so-called bucket
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brigade) as described above to cause information to reach a remote information
processing device is called multi-hop relay. In addition, a network which pe1forms
multi-hop is generally known as a mesh network.
[0035]
5 A configuration of an information processing device which constitutes such
an ad hoc network or a mesh network is shown in FIG. 2. In addition, multi-hop
relay will be described in more detail with reference to FIGS. 4, 10, and the like.
[0036]
In addition, among the information processing devices which constitute the
10 communication system 200 in the embodiments of the present technology, an
information processing device which serves as a reference (for example, an
information processing device which receives a signal) will be referred to as a selfstation,
and other information processing devices will be referred to as a transmitting
station, a receiving station, a transmission source station, a destination station, and a
· 15 nearby station.
[0037]
In more detail, an information processing device which transmits a signal
received by the self-station will be refened to as a transmitting station, and an
information processing device which receives a signal from the self-station will be
20 referred to as a receiving station. In addition, a transmission source informatiou
processing device which first transmits a signal received by the self-station (a socalled
leader of a bucket brigade) will be referred to as a transmission source station,
and an infonnation processing device which receives a signal received by the selfstation
in the end (a so-called terminus of the bucket brigade) will be referred to as a
25 destination station. In addition, an information processing device which transfers a
signal received by the self-station will be refened to as a relay station, and an
information processing device which is near or in the vicinity of the self-station on a
network will be referred to as a nearby station.
[0038]
30 [Configuration example of an information processing device]
FIG. 2 is a block diagram showing an intemal configuration example of the
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information processing device 100 according to the first embodiment of the present
technology. Herein, only the information processing device I 00 will be described
because internal configurations of the other information processing devices (the
information processing devices 210, 220, 230, and 240) are the same as that of the
5 information processing device 100, and thus other information processing devices
will not be described.
[0039]
The information processmg device 100 includes an antenna 110, a
communication unit 120, an input/output (110) inte1face 130, a control unit 140, and
10 a memory 150. In addition, these units are connected to one another via a bus 160.
[0040]
The communication unit 120 is a module (for example, a modem) for
performing transmission and reception of radio waves via the antenna 110. For
example, the cornnmnication unit 120 can perform wireless communication through
15 millimeter wave communication (60 GHz, etc.), a wireless local area network (LAN)
of 900 MHz, 2.4 GHz, or 5 GHz, or an ultra-wide band (UWB). In addition, the
communication unit 120 can perfonn wireless communication through, for example,
visible light communication or near field communication (NFC).
[0041]
20 For example, the communication unit 120 exchanges a signal (an RANN, a
PREQ, or a PREP) for generating or updating a cornnmnication path of multi-hop
using wireless communication with another information processing device based on
control of the control unit 140. The RANN, PREQ, and PREP will be described in
detail with reference to FIG. 4, and the like.
25 [0042]
It should be noted that the communication unit 120 may be designed to
perform wireless communication using radio waves (electromagnetic waves) or
wireless communication using a medium other than radio waves (for example,
wireless communication pmformed using a magnetic field).
30 [0043]
In addition, the communication unit 120 performs communication with a
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nearby information processing device by setting up a communication link, manages
the number of nearby information processing devices with which the information
processing device 100 can communicate, and retains information which indicates the
number of nearby communicable information processing devices (communicable
5 device number information). Furthermore, the communication unit 120 regularly or
inegularly observes a degree of use of a channel used in wireless communication,
and retains information which indicates a level of congestion of a communication
line around the infonnation processing device 100 (congestion level infonnation).
In addition, the communication unit 120 obsetves link quality (reception power, a
10 transmittable data rate, etc.) \vith a nearby information processing device performing
wireless communication therewith, and retains information which indicates a
bandwidth which makes wireless communication with a nearby information
processmg device possible (communication state information). Then, the
communication unit 120 supplies the information to the control unit 140.
15 [0044]
The 110 interface 130 is an interface with an external device such as a
sensor actuator which operates in linkage with the infmmation processing device 100.
FIG. 2 shows an example in which, for example, a movement detection unit 171, an
operation reception unit 172, a display unit 173, and an audio output unit 174 are
20 connected with the 110 interface 130 as external devices. In addition, FIG. 2 shows
the example in which the movement detection unit 171, the operation reception unit
I72, the display unit 173, and the audio output unit 174 are provided outside the
information processing device 100, but all or some of the units may be installed
inside the information processing device I 00.
25 [0045]
The movement detection unit 171 detects a movement of the information
processing device 100 by detecting acceleration, a motion, an inclination, or the like
of the information processing device I 00, and outputs movement information
regarding the detected movement to the control unit 140 via the 110 interface 130.
30 For example, the movement detection unit 171 retains movement information which
indicates whether or not the information processing device 100 is moving to a
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different place (a log (or real-time information regarding the movement)), and
supplies the infonnation to the control unit 140. As the movement detection unit
171, for example, an acceleration sensor, a gyro sensor, or the Global Positioning
System (GPS) can be used. The movement detection unit 171 can compute a
5 movement distance of the information processing· device 100 (for example, a
movement distance per unit time) using, for example, position information (for
example, latitude and longitude) detected using the GPS.
[0046]
The operation reception unit 172 is an operation reception unit which
10 receives an operation input performed by a user, and outputs operation information
according to the received operation input to the control unit 140 via the VO interface
130. The operation reception unit 172 is realized with, for example, a touch panel,
a keyboard, or a mouse.
15
[0047]
The display unit 173 is a display unit on which various kinds of infmmation
are displayed based on control of the control unit 140. As the display unit 173, for
example, a display panel such as an organic electro luminescence (EL) panel, or a
liquid crystal display (LCD) can be used. The operation reception unit 172 and the
display unit 173 can be configured to be integrated using a touch panel on which
20 operations can be input by a user bringing his or her finger in contact with or close to
its display plane.
[0048]
The audio output unit 174 is an audio output unit (for example, a speaker)
which outputs various kinds of sounds based on control of the control unit 140.
25 [0049]
The control nnit 140 controls each unit of the infonnation processing device
100 based on a control program stored in the memory 150. The control unit 140
perfotms, for example, signal processing of transmitted and received information.
In addition, the control unit 140 is realized with a central processing unit (CPU).
30 [0050]
The memory !50 is a memory which stores various kinds of information.
,•
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For example, the memmy !50 stores various kinds of information necessary for the
information processing device I 00 to perform a desired operation (for example, the
control program). In addition, the memory !50 stores, for example, the mesh path
table 350 shown in FIG. II. Fmihermore, the memory !50 stores various kinds of
5 content such as music content and image content (for example, dynamic image
content and still image content).
[0051]
When data is transmitted using wireless communication, for example, the
control unit 140 processes information read from the memory !50, a signal input
10 fi·om the 110 interface 130, or the like, and generates a mass of data to be actually
transmitted (transmission packets). Successively, the control unit 140 outputs the
generated transmission packets to the communication unit 120. In addition, the
communication unit 120 converts the transmission packets in a format of a
communication scheme for actual transfer or the like, and transmits the converted
15 transmission packets to the outside from the antenna 110.
[0052]
In addition, when data is received using wireless communication, for
example, the communication unit 120 extracts reception packets of radio waves
received via the antenna II 0 through signal processing performed by a receiver
20 inside the conununication unit 120. Then, the control unit 140 analyzes the
extracted reception packets. When the packets are determined to be data to be
retained as a result of the analysis, the control unit 140 writes the data in the memmy
!50. In addition, when the packets are determined to be data to be transferred to
another infonnation processing device, the control unit 140 outputs the data to the
25 communication unit 120 as transmission packets to be transmitted to another
infonnation processing device. Furthermore, when the packets are determined to be
data to be transferred to an external actuator, the control unit 140 outputs the packets
to the outside (for example, the display unit 173) from the 110 interface 130.
30
[0053]
The control unit 140 can, for example, provide various kinds of content
stored in the memory 150 to another infmmation processing device using wireless
19/113
communication.
[0054]
It should be noted that, when the information processing device I 00 is
driven by a battery, a battery is mounted (installed or loaded) in the information
5 processing device 100. In this case, the control unit 140 has a function of
estimating a remaining battery amount, and thus can acquire the estimated remaining
battery amount as needed.
10
15
[0055]
[Example of a signal format]
FIG. 3 is a diagram showing an example of a signal format of a packet
exchanged between infmmation processing devices which constitute the
communication system 200 according to the first embodiment of the present
technology.
[0056]
Here, each of the information processing devices constituting the
communication system 200 exchanges signals in a packet form during
communication. The signal in the packet form includes at least two types including
a management packet and a data packet. Thus, a of FIG. 3 shows an example of the
signal format of a management packet and b of FIG. 3 shows the signal fonnat of a
20 data packet.
25
30
[0057]
The managementpacket shown in a of FIG. 3 is a packet used for generating
and retaining a network.
[0058]
As shown in a of FIG. 3, the transmission signal of the management packet
is composed of a header part (30 1 to 303) and a payload part 304. In addition, there
are three fields in the header part. These three fields are a Frame Control field 30 I,
an RX STAADDR field 302, and a TX STAADDR field 303.
[0059]
In the leading pmt of the header part, there is the Frame Control field 301 in
which an attribute of a signal including this header and the like m·e stored. Each
5
SP353494WOOO
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information processing device can acquire information of whether a packet is a data
packet or a management packet for control and management and the like with
reference to the Frame Control field 301.
[0060]
In the RX STA ADDR field 302, an identifier (address) indicating a packet
receiving station is stored. Each information processing device can know which
information processing device is supposed to receive the signal (packet) with
reference to the RX STA ADDR field 302. An information processing device which
has received the signal (packet) statts a reception process of the received signal
10 (packet) when, for example, content of the RX STA ADDR field 302 is its own
identifier (address) or a broadcast address.
[0061]
In the TX STA ADDR field 303, an identifier (address) of a packet
transmitting station. Each information processing device can recognize which
15 information processing device has transmitted the signal with reference to the TX
STA ADDR field 303.
[0062]
The data packet shown in b of FIG. 3 is a packet used when application data
or the like is transmitted. ·
20 [0063]
As shown in b of FIG. 3, the transmission signal of the data packet is
composed of a header part (305 to 309) and a payload part 310. In addition, there
are 5 fields in the header part. These 5 fields are a Frame Control field 305, an RX
STA ADDR field 306, a TX STA ADDR field 307, a Dst STA ADDR field 308, and
25 an Src STAADDR field 309.
[0064]
In the leading part of the header patt, there is the Frame Control field 305 in
which an attribute of a signal including this header and the like are stored. Each
information processing device can acquire information of whether a packet is a data
30 packet or a management packet for control and management and the like with
reference to the Frame Control field 305.
SP353494WOOO
211113
[0065]
In the RX STA ADDR field 306, an identifier (address) indicating a packet
receiving station is stored. Each information processing device can know which
information processing device is supposed to receive the signal (packet) with
5 reference to the RX STA ADDR field 306. An information processing device which
has received the signal (packet) starts a reception process of the received signal
(packet) when, for example, content of the RX STA ADDR field 306 is its own
identifier (address) or a broadcast address.
10
15
[0066]
In the TX STA ADDR field 307, an identifier (address) of a packet
h"ansmitting station. Each information processing device can recognize which
information processing device has transmitted the signal with reference to the TX
STAADDR field 307.
[0067]
In the Dst STA ADDR field 308, an identifier (address) indicating a packet
destination station (an information processing device which is supposed to receive
the packet in the end) is stored. Each information processing device can know to
which information processing device the signal is supposed to be transmitted in the
end with reference to the Dst STA ADDR field 308. An information processing
20 device which has received the signal performs a transfer process to transmit the
received signal to a destination station when, for example, the Dst STA ADDR field
308 does not include its own identifier (address).
[0068]
In the Src STA ADDR field 309, an identifier (address) of a packet
25 transmission source station (an information processing device which first transmitted
the packet first) is stored. For example, each information processing device can
recognize which information processing device has transmitted the signal with
reference to the Src STAADDR field 309.
30
[0069]
Here, when data destined for a specific information processing device is
transferred through the above-described multi-hop relay, it is necessary to decide a
SP353494WOOO
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path on which the data is to be relayed before the data is transferred. This
procedure is called path selection. In addition, in this path selection, a
communication path is decided by exchanging a management signal between
information processing devices for selecting a path. It should be noted that a
5 communication path on a mesh network is called a mesh path. In FIGS. 4 to 7,
types and formats of management signals used for generating this mesh path are
shown.
10
15
[0070]
[Examples of signal fonnats]
FIG. 4 is a diagram showing an example of a signal format of a management
packet exchanged between the information processing devices which constitute the
communication system 200 according to the first embodiment of the present
technology.
[0071]
FIGS. 5 to 7 are diagrams showing examples of the content of the signal
fmmats of the management packet exchanged between the information processing
devices which constitute the communication system 200 according to the first
embodiment of the present technology. In other words, FIGS. 5 to 7 show the
examples of the content of the signal formats of the management packets shown in
20 FIG. 4.
[0072]
a of FIG. 4 shows the management packet. This management packet is the
same as that of a of FIG. 3. As described above, the Frame Control field 301 of the
management packet stores the fact that the signal is a management packet.
25 [0073]
b to d of FIG. 4 show a configuration example of the payload part 304 of the
management packet shown in a of FIG. 4. Specifically, b of FIG. 4 shows a
configuration example of a case in which the management packet is an RANN (root
announcement signal). In addition, c of FIG. 4 shows a configuration example of a
30 case in which the management packet is a PREQ (path request signal). Also, d of
FIG. 4 shows a configuration example of a case in which the management packet is a
PREP (path reply signal).
[0074]
23/113
SP353494WOOO
The RANN (root announcement signal) shown in b of FIG. 4 is a signal used
for proactively generating a mesh path regardless of presence of transmission data.
5 Here, the case in which a mesh path is proactively generated is a case in which,
regardless of necessity of data transfer, a mesh path between a specific infmmation
processing device and another infmmation processing device on a network is
generated beforehand.
10
[0075]
RANN.
[0076]
stored.
As shown in b of FIG. 4, there are a plurality of fields (311 to 318) in the
In the Length field 311, information indicating the length of the payload is
15 [0077]
In the ActionType field 312, an identifier indicating that the signal is an
RANN is stored. An information processing device which has received the signal
can recognize that the received signal is an RANN with reference to the Action Type
field 312.
20 [0078]
In the Flags field 313, an attribute of a transmission source station of the
RANN (information processing device which has transmitted the RANN first) is
stored. This attribute is information indicating, for example, a role of the
information processing device. For example, when the information processing
25 device which has transmitted the RANN first (transmission source station) is a
device for causing another information processing device to be connected to the
Intemet, the Flags field 313 stores that fact.
[0079]
In the OrigSTA field 314, an identifier (address) indicating which
30 information processing device is the transmission source station of the RANN
(information processing device which has transmitted the RANN first) is stored.
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Here, although the RANN is transferred to a remote spot through multi-hop relay, an
information processing device which has received the RANN can recognize which
information processing device is the transmission source station of the received
RANN with reference to OrigSTA field 314.
5 [0080]
In the SeqNum field 315, an identifier for identifYing the RANN is stored.
For example, each time the RANN is transmitted from the transmission source
station, an incremented value is stored in the SeqNum field 315. In other words, as
the RANN is regularly or irregularly transmitted fi·om the transmission source station,
10 an infmmation processing device which has received the RANN can recognize
whether or not the received RANN is the same RANN as that received before with
reference to the SeqNum field 315.
[0081]
In the HopCount field 316, a numerical value indicating the number of hops
15 necessmy for the RANN to be delivered fi·om the transmission source station
(information processing device which has transmitted the RANN first) is stored.
An information processing device which has received the RANN transfers the
received RANN in multi-hop, and an incremented value is stored in the HopCount
field 316 with each the transfer process.
20 [0082]
In the Metric field 317, a value indicating a metric value that was necessary
for arrival of the RANN fi-om the transmission source station (information processing
device which has transmitted the RANN first) is stored. An information processing
device which has received the RANN transfers the received RANN in multi-hop, and
25 the Metric field 3 I 7 stores a value obtained by cumulatively adding metric values of
a link between infotmation processing devices with each transfer process.
[0083]
Here, a metric value of a link between information processing devices is a
value indicating, for example, at how many Mbps transfer is possible on that link.
30 In the IEEE standard 802.11-2012, for example, a metric value ca can be obtained
fi·om the following expression I.
SP353494WOOO
251113
ca = (0+ (Bt/r)]/[11(1-ef)] ... Expression 1
(0084]
Here, r is a value indicating a data rate (Mb/s). In addition, ef is a value
indicating a fi·ame error rate. Further, Bt is a value indicating a frame size. Also,
5 0 is an intrinsic value of a physical layer (PHY).
(0085]
In the Etc field 318, other management information is stored.
(0086]
The PREQ (path request signal) shown in c of FIG. 4 is a signal used for
10 requesting generation of a mesh path destined for a specific information processing
device.
(0087]
As shown in c of FIG. 4, there are a plurality of fields (319 to 328) in the
PREQ.
15 (0088]
In the Length field 319, infmmation indicating the length of the payload is
stored.
(0089]
In the ActionType field 320, an identifier indicating that the signal is a
20 PREQ is stored. An information processing device which has received the signal
can recognize that the received signal is a PREQ with reference to the ActionType
field 320.
(0090]
In the Flags field 321, information indicating whether the PREQ has been
25 transmitted triggered by reception of the RANN (whether this is a proactive mesh
path generation process) is stored.
[0091]
In the OrigSTA field 322, an identifier (address) indicating an information
processing device serving as a requesting source of mesh path generation
30 (transmission source station) is stored. Here, although the PREQ is transferred to a
remote spot through multi-hop relay, an information processing device which has
5
SP353494WOOO
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received the PREQ can recogmze which infonnation processmg device is the
transmission source station of the received PREQ with reference to the OrigSTA field
322.
[0092]
In the DestSTA field 323, an identifier indicating an information processing
device serving as a request destination of mesh path generation (destination station)
is stored. When an information processing device specified with the identifier
stored in the DestSTA field 323 (destination station) receives the PREQ, the device
replies with a PREP in response thereto. Accordingly, a bidirectional mesh path is
10 generated.
[0093]
In the SeqNum field 324, an identifier for identifying the PREQ is stored.
For example, each time the PREQ is transmitted from the transmission source station,
an incremented value is stored in the SeqNum field 324. In other words, there are
15 cases in which, although the PREQ is transmitted from the transmission source
station a plurality of times, an information processing device which has received the
PREQ can recognize whether or not the received PREQ is the same one as a PREQ
received before with reference to the SeqNum field 324.
20
[0094]
In the HopCount field 325, a numerical value indicating the number of hops
necessary for the PREQ to be delivered from the transmission source station
(information processing device which has transmitted the PREQ first) is stored. An
information processing device which has received the PREQ transfers the received
PREQ in multi-hop, and an incremented value is stored in the HopCount field 325
25 with each the transfer process.
[0095]
In the Metric field 326, a value indicating a metric value that was necessaty
for arrival of the PREQ fi-om the transmission source station (infonnation processing
device which has transmitted the PREQ first) is stored. An infonnation processing
30 device which has received the PREQ transfers the received PREQ in multi-hop, and
the Metric field 326 stores a value obtained by cumulatively adding metric values of
SP353494WOOO
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a link between information processing devices with each transfer process.
[0096]
In the Lifetime field 327, information indicating a lifetime of a mesh path is
stored. In other words, when a mesh path generation request succeeds, a valid mesh
5 path (active mesh path) is generated, and a value for specifying the lifetime of the
mesh path is stored in the Lifetime field 327.
10
[0097]
In the Etc field 328, other management information is stored.
[0098]
The PREP (path reply signal) shown in d of FIG. 4 is a signal used for reply
to a request to generate a mesh path destined for a specific information processing
device.
[0099]
As shown in d of FIG. 4, there are a plurality of fields (329 to 338) in the
15 PREP.
20
[0100]
stored.
[0101]
In the Length field 329, information indicating the length of the payload is
In the ActionType field 330, an identifier indicating that the signal is a
PREP is stored. An information processing device which has received the signal
can recognize that the received signal is a PREP with reference to the ActionType
field 330.
[0102]
25 In the Flags field 331, an attribute of a transmission source station of the
PREP (an information processing device which has transmitted the PREP first) is
stored.
[01 03]
In the OrigSTA field 332, an identifier indicating an information processing
30 device serving as a requesting source for generating a mesh path is stored. Here,
the identifier of the information processing device stored in the OrigSTA field 322 of
SP353494WOOO
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the PREQ (transmission source station of the PREQ) is transcribed in the OrigSTA
field 332.
[0104]
In the DestSTA field 333, an identifier indicating an information processing
5 device serving as a request destination for generation of the mesh path is stored.
10
Here, the identifier of the information processing device stored in the DestSTA field
323 of the PREQ (destination station of the PREQ) is transcribed in the DestSTA
field 333.
[0 1 05]
In the SeqNum field 334, an identifier for identifying the PREP is stored.
For example, each tin1e the PREP is transmitted from the transmission source station,
an incremented value is stored in the SeqNum field 334. In other words,. there are
cases in which, although the PREP is transmitted from the transmission source
station a plurality of times, a destination station which has received the PREP can
15 recognize whether or not the received PREP is the same one as a PREP received
before with reference to the SeqNum field 334.
[0106]
In the HopCount field 335, a numerical value indicating the number of hops
necessary for the PREP to be delivered from the transmission source station of the
20 PREP is stored. An information processing device which has received the PREP
transfers the received PREP in multiple-hop, and an incremented value is stored in
the HopCount field 335 with each transfer process.
[0107]
In the Metric field 336, a value indicating a metric value that was l).ecessary
25 for anival of the PREP from the transmission source station is stored. An
information processing device which has received the PREP transfers the received
PREP in multi-hop, and the Metric field 336 stores a value obtained by cumulatively
adding metric values of a link between information processing devices with each
transfer process.
30 [0108]
In the Lifetime field 33 7, information indicating a lifetime of a mesh path is
~J
8
5
SP353494WOOO
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stored. In other words, when a mesh path generation request succeeds, a valid mesh
path (active mesh path) is generated, and a value for designating the lifetime of the
mesh path is stored in the Lifetime field 337.
[0109]
In the Etc field 338, other management information is stored.
[OliO]
TI1e infmmation processing devices constituting the communication system
200 generate path information (also referred to as transfer information or mesh path
information) necessary during multi-hop conmumication by exchanging the RANN,
10 the PREQ, and the PREP. For example, the infonnation processing devices
generates a multi -hop communication path at a fixed time interval or irregularly by
exchanging the RANN, the PREQ, and the PREP. In addition, the path information
is path infmmation for specifYing the next infonnation processing device to which
packets should be transferred in order to deliver the packets to a destination
15 information processing device. This path information is retained inside each
infonnation processing device as a mesh path table. In addition, when transmitting
data packets to a specific information processing device, each information processing
device decides an information processing device to be designated as a receiving
station to transmit the packets with reference to the mesh path table. In other words,
20 when transmitting data packets to a specific infmmation processing device, each
information processing device decides what information processing device should be
designated in the RX STA ADDR field 302 to transmit the packets with reference to
the mesh path table. This mesh path table will be described in detail with reference
to FIGS. 8, II, and the like.
25 [0111]
[Configuration example of a mesh path table]
FIG. 8 is a diagram schematically showing an example of a mesh path table
(mesh path table 340) retained by each information processing device which
constitutes the communication system 200 according to the first embodiment of the
30 present teclmology.
[0112]
SP353<194WOOO
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a of FIG. 8 schematically shows a configuration of the mesh path table 340,
and b of FIG. 8 shows an example of the content of the mesh path table 340.
Specifically, b of FIG. 8 shows an Index 346, a data name 34 7, and a meaning 348 as
the example of the content of the mesh path table 340.
5 [0113]
As shown in a of FIG. 8, the mesh path table 340 is recorded in the memory
150 in a record form. In addition, the mesh path table 340 is designed such that
each record can be extracted therefrom using the address (Dest 341) of a destination
station as a key. In addition, as records of the mesh path table 340, a NextHop 342,
10 a Metric 343, a SeqNum 344, and an ExpTime 345 are stored. It should be noted
that, in b of FIG. 8, reference symbols a to d for identifYing each of the records are
given in the Index 346.
[0 114]
In the NextHop 342 of "a" of the Index 346, an identifier of an information
15 processing device indicating to what information processing device data should be
transferred next in order to deliver the data to a destination station is stored. In
other words, the NextHop 342 stores an identifier of a transmitting station.
[OI15]
In the Metric 343 of"b" of the Index 346, a path metric value from a self-
20 station to the destination station of the mesh path is stored. A computation method
for tllis path metric value will be shown in FIGS. 9, 10, etc.
[OII6]
In the SeqNum 344 of "c" of the Index 346, the value of SeqNum of the
PREQ or the PREP (for example, the SeqNum fields 324 and 334 shown in c and d
25 of FIG. 4) used to generate the mesh path is stored.
[0117]
In the ExpTime 345 of"d" of the Index 346, the expiration time of the mesh
path is stored. The expiration time of the mesh path is decided based on the
Lifetime fields 327 and 337 of the PREQ or the PREP (shown inc and d of FIG. 4)
30 used to generate the mesh path.
[0118]
SP353<194WOOO
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Each information processing device constituting the communication system
200 generates path information at the time of a request of generation of a path or a
reply thereto, and writes the generated path information in the mesh path table 340.
In addition, when transferring data, based on the address (Dest 341) of a destination
5 station to which the data is to be delivered, each information processing device
constituting the conmumication system 200 extracts a record cmTesponding to the
destination station fi·om the mesh path table 340. In addition, the information
processing device perfmms a transfer process for transferring the data to a
transmitting station corresponding to the NextHop 342 of the extracted record.
10 [0119]
[Generation example of a mesh path]
FIGS. 9 and 10 are diagrams showing a generation example of a mesh path
retained by each information processing device constituting the communication
system 200 according to the first embodiment of the present technology.
15 [0120]
In FIGS. 9 and 10, the procedure for generating the mesh path table 340
using a PREQ and a PREP will be described. Specifically, in FIGS. 9 and 10, a
case in which, when the information processing device 100 attempts to transmit data
destined for the information processing device 240 in the topology shown in FIG. 1,
20 the information processing device 100 requests generation of a mesh path between
the information processing device 240 will be described.
[0121]
As shown in a of FIG. 9, the information processing device 100 transmits a
PREQ in which the information processing device 240 has been designated in the
25 Dest STA field 323 (shown in c of FIG. 4). A configuration of the PREQ has been
shown in c of FIG. 4 and FIG. 6. In addition, when the PREQ is transmitted, the
control unit 140 of the information processing device 100 stores zero as an initial
value in the HopCount field 325 and the Metric field 326 of the PREQ to be
transmitted. Furthermore, the control unit 140 of the information processing device
30 100 stores a value obtained by incrementing the value stored in the PREQ that was
transmitted the previous time in the SeqNum field 324 of the PREQ to be transmitted.
SP353494WOOO
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In addition, the control unit 140 of the information processing device I 00 sets a
broadcast address for designating each information processing device located nearby
as a receiving station in the RX STA ADDR field 303 (shown in a of FIG. 4) of the
management packet of the PREQ to be transmitted.
5 [0122]
It should be noted that, in a of FIG. 9, the flow of the PREQ tr·ansmitted
from the information processing device I 00 to each information processing device is
schematically shown with thick-line arrows. In addition, the name of the signal
(PREQ), the reference symbol of the destination station (Dest=E), and the reference
10 symbol of the transmission source station and relay station (including the
transmitting station) of the PREQ (A) are given to the thick-line arrows.
[0123]
For example, PREQ Dest=E(A) shown in a of FIG. 9 means that it is a
PREQ of which the destination station is the information processing device 240 and
15 the transmission source station and the relay station (including the transmitting
station) are the information processing device I 00. It should be noted that the same
applies to the names and reference symbols of thick-line arrows in the following
drawings.
20
[0124]
As shown in a of FIG. 9, the information processing devices 210, 220, and
230 receive the PREQ transmitted from the infmmation processing device I 00.
Upon receiving the PREQ, the information processing devices 210, 220, and 230
generate path information destined for an information processing device (destined for
the information processing device I 00) of which the identifier is stored in the
25 OrigSTA field 322 of the received PREQ. In addition, the information processing
devices 210, 220, and 230 records the generated path information in the mesh path
table 340 as path information destined for the information processing device I 00.
[0125]
In this case, each information processing device stores the identifier
30 (address) of the information processing device 100 in the Dest 341 of the mesh path
table 340. In addition, each information processing device stores the identifier
SP353494WOOO
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(address) of the TX STA ADDR field 303 of the received PREQ in the NextHop 342
of"a" of the Index 346 of the mesh path table 340.
[0126]
Furthermore, each of the information processing devices acquires a metric
5 value of a link between a transmitting station of the received PREQ and the selfdevice.
For example, the information processing device 210 acquires a metric value
of a link between the transmitting station (the information processing device I 00) of
the received PREQ and the self-device (the information processing device 210).
Subsequently, each infonnation processing device computes a path metric value by
10 adding the acquired metric value of the link to the value stored in the Metric field
326 of the received PREQ. Then, each information processing device stores the
computed path metric value in the Metric 343 of "b" of the Index 346 of the mesh
path table 340.
15
[0127]
Here, the transmitting station of the received PREQ is the infom1ation
processing device corresponding to the identifier stored in the TX STA ADDR field
303, and is the infmmation processing device 100 in the example shown in FIG. 9.
In addition, the metric value of the link between the transmitting station of the
received PREQ and the self-device is, for example, a value which indicates at how
20 many Mbps transfer is possible on that link.
[0128]
Fmthermore, each information processing device stores the value of the
SeqNum field 324 of the received PREQ in the SeqNum 344 of"c" oftl1e Index 346
of the mesh path table 340.
25 [0129]
In addition, each infonuation processing device stores the value obtained by
adding the value stored in the Lifetime field 327 of the PREQ to the reception time
of the PREQ (expiration time) in the ExpTime 345 of "d" of the Index 346 of the
mesh path table 340. The mesh path generated in that manner is referred to as a
30 value mesh path until the expiration time stored in the ExpTime 345 of "d" of the
Index 346 of the mesh patl1 table 340.
34/113
[0130]
In this manner, the information processmg devices 210, 220, and 230
generate the mesh path destined for the information processing device 100.
[0131]
5 Fmthennore, as shown in b of FIG. 9, the respective information processing
devices 210, 220, and 230 which have received the PREQ transfer the received
PREQ because the identifier of the DestSTA field 323 of the received PREQ is not
theirs. At the time of this transfer, the information processing devices 210, 220, and
230 increment the value of the HopCount field 325 of the received PREQ. Titen,
10 the previously calculated path metric value is stored in the Metric field 326, and the
value of the received PREQ is transcribed in the field of another PREQ. In addition,
the information processing devices 210, 220, and 230 set a broadcast address for
designating each information processing device located nearby as a receiving station
in the RX STAADDR field 302.
15 [0132]
Upon rece1vmg the transferred PREQ, for example, the information
processing device 240 generates path information destined for the infmmation
processing device (destined for the information processing device 100) of which the
identifier is stored in the OrigSTA field 322 of the received PREQ in the above-
20 described procedure. Then, the information processing device 240 recmds the
generated path information in the mesh path table 340 as path information of which
the recipient is set to the information processing device 100.
[0133]
Here, as shown in b of FIG. 9, the information processing device 240
25 receives such PREQ from the information processing devices 220 and 230. When
the PREQ has received from a plurality of information processing devices in this
manne1~ the information processing device 240 selects a path having a low path
metric value as a valid mesh path, and discards a PREQ having a high path metric
value.
30 [0134]
In the example shown in FIG. 9, a case in which the path metric value of the
35/113
PREQ transferred from the information processing device 230 is lower than the path
metric value of the PREQ transferred from the information processing device 220 is
assumed. In this case, the information processing device 240 generates a mesh path
of which the NextHop 342 is set to the information processing device 230 as a mesh
5 path designed for the information processing device 100.
[0135]
In addition, since the information processing device 240 designates selfdevice
as the DestSTA field 323 of the received PREQ, the device generates a PREP
for replying to this PREQ. Thus, as shown in a of FIG. 10, the information
10 processing device 240 transmits the generated PREP by designating the NextHop
destined for the OrigSTA field 322 of the PREQ as a receiving station.
[0136]
In this case, the infmmation processing device 240 transcribes the values
stored in the PREQ in the OrigSTA field 332 and the DestSTA field 333, and stores
15 zero as an initial value in the HopCount field 335 and the Metric field 336. In
addition, the information processing device 240 stores in the SeqNum 344 the value
obtained by incrementing the value stored in the previously transmitted PREQ or
PREP. In addition, the information processing device 240 sets the NextHop
destined for OrigSTA of the PREQ (the information processing device 230 in this
20 case) in the RX STA ADDR field 302 for transmission to the information processing
device 230 in unicast.
[0137]
Upon rece1vmg the PREP transmitted from the information processing
device 240, the information processing device 230 generates path information
25 destined for an information processing device (destined for the information
processing device 240) of which the identifier is stored in the DestSTA field 333 of
the received PREP in the above-described procedure. Then, the information
processing device 230 records the generated path information in the mesh path table
340 as path information of which the destination is set to the information processing
30 device 240. In this manner, upon receiving the PREP transmitted from the
infonnation processing device 240, the information processing device 230 generates
36/113
a mesh path destined for the information processing device 240.
[0138]
SP353494WOOO
As shown in b of FIG. 10, the identifier of the OrigSTA field 332 of the
received PREP is not of the information processing device 230 which has received
5 the PREP. For this reason, the infonnation processing device 230 transfers the
received PREP to the infonnation processing device which corresponds to the
identifier of the OrigSTA field 332 of the received PREP. At the time of this
transfer, the information processing device 230 increments the value of the
HopCount field 335 of the received PREP. Then, a path metric value calculated in
10 the above-described procedure is stored by the information processing device 203 in
the Metric field 336, and the value of the received PREP is transcribed in the field of
another PREP. In addition, in order to transmit the PREP in unicast, the information
processing device 230 sets the address of the NextHop 342 of the mesh path destined
for the information processing device 100 (the address of the information processing
15 device 1 00) in the RX STA ADDR field 302. Accordingly, unicast transmission of
the PREP from the information processing device 230 to the information processing
device 100 is performed as shown in b of FIG. 10.
[0139]
Upon receiVIng the PREP transmitted from the information processing
20 device 230, the information processing device 100 generates path information
destined for the information processing device of which the identifier is stored in the
DestSTA field 333 of the received PREP (destined for the information processing
device 240) in the above-described procedure. Then, the information processing
device 100 records the generated path information in the mesh path table 340 as path
25 information of which the destination is set to the information processing device 240.
[0140]
In this marmer, the information processing device 100 generates a mesh path
destined for the information processing device 240. In addition, since the identifier
of the OrigSTA field 332 of the received PREP is of the information processing
30 device 100, the device finishes the bi-directional mesh path generation procedure
between the information processing device 100 and the information processing
E"'Il
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device 240 without performing a successive transfer process.
[0141]
Thereafter, the mesh path records generated and retained in each of the
information processing devices can be referred to before the expiration time
5 (ExpTime 345) of the generated mesh path elapses. For this reason, before the
expiration time elapses, when data is exchanged between the infmmation processing
device I 00 and the infmmation processing device 240, the mesh path records
retained in each of the information processing devices can be referred to to perform
communication in multi-hop relay.
10 [0142]
When there is a mesh path of which the expiration time has anived, each
information processing device destroys the mesh path of which the expiration time
has arrived, and re-generates a mesh path destined for the information processing
device of which the expiration time has arrived.
15 [0143]
20
It should be noted that, although the mesh path can be generated by
exchanging another signal (for example, RANN), description thereof is omitted here.
[0144]
[Regarding generation and maintenance management of a mesh path]
As described above, each of the information processing devices which
constitute the communication system 200 exchanges signals (PREQ, PREP, and
RANN) to generate and perform maintenance management of a mesh path. Thus, it
is impmtant to more appropriately perform generation and maintenance management
of a mesh path by making a change or addition to each of the processes. This point
25 will be described below.
[0145]
[Regarding a mesh path updating timing]
When there is a mesh path of which the expiration time has aJTived, each of
the information processing devices which constitute the communication system 200
30 destroys the mesh path (path information) of which the expiration time has arrived,
as described above. Thus, it is not possible to transmit a next data packet for the
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time until a mesh path is generated again.
[0146]
SP353494WOOO
Thus, in the first embodiment of the present technology, an example in
which a mesh path is updated before the mesh path is destroyed will be shown.
5 [0147]
[Regarding a mesh path updating timing]
When there is a mesh path of which the expiration time has arrived, each of
the information processing devices which constitute the communication system 200
destroys the mesh path of which the expiration time has arrived, as described above.
10 Then, generation of a mesh path to a destination station is started. In this case,
because a number of PREQs and PREPs are transmitted fi·om the plurality of
information processing devices substantially at the same timing, there is concern of
radio waves being congested.
15
20
[0148]
Therefore, in the first embodiment of the present technology, an example in
which different mesh path generation timings are set for the plurality of information
processing devices will be shown.
[0149]
[Regarding a value of LifeTime]
Here, a situation of a mesh path is assumed to change due to movement of
an information processing device, appearance of a new information processing
device, or the like. However, when a situation of a mesh path is not likely to
change, for example, if a value of LifeTime is constant, there is concern of the mesh
path being ullllecessarlly updated. On the other hand, when a situation of a mesh
25 path is likely to change, if the value of LifeTime is constant, there is concern of
updating of the mesh path being delayed. Thus, it is impmtant to appropriately
update a mesh path by appropriately setting the value of LifeTime.
[0 150]
Therefore, in the first embodiment of the present technology, an example in
30 which the value of LifeTime is changed according to a state (for example, a
movement state, or a communication state) of an information processing device will
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be shown.
[0151]
[Regarding a metric value]
The metric value ca can be obtained using the following Expression 1 in, for
5 example, the IEEE 802.11-2012 standard, as described above.
ca = [O+(Bt/r)]/[11(1-ef)] ... Expression 1
[0152]
Here, when there is no data communication petformed for a long period of
time, there are cases in which a data rate is not updated and it is not possible to deal
10 with a change in a situation. In addition, when data communication is performed
only for obtaining a metric value, unnecessary traffic occurs.
[0153]
Thus, in a second embodiment of the present teclmology, an example in
which a metric value is obtained by appropriately using an error rate will be shown.
15 [0154]
[Regarding comparison of metric values when a mesh path is to be selected]
A case in which, when a mesh path is to be selected, the metric values of
two or more paths are similar is also assumed. In such a case, there is concern of
paths being switched each time a mesh path is switched and parameters which are
20 affected by the paths being easily changed.
[0155]
Therefore, in the second embodiment of the present technology, an example
in which frequent switching of mesh paths is prevented by applying hysteresis to
selection of a mesh path will be shown.
25 [0156]
It should be noted that, as a technology for configuring such a wireless
network system described above, the IEEE standard 802.11-2012 (IEEE Standard for
Information Technology - Telecommunications and information exchange between
systems - Local and metropolitan area networks - Specific requirements Part 11:
30 Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specifications) is widely known.
SP353494WOOO
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[0 157]
[Configuration example of a mesh path table]
FIG. 11 is a diagram schematically showing an example of a mesh path table
(mesh path table 350) retained by each information processing device which
5 constitutes the communication system 200 according to the first embodiment of the
present teclmology.
[0 158]
a of FIG. 11 schematically shows a configuration of a mesh path table 350,
and b of FIG. 11 shows an example of the content of the mesh path table 3 50.
10 Specifically, in b of FIG. 11, the Index 346, the data name 347, and the meaning 348
are shown as the example of the content of the mesh path table 350. It should be
noted that the mesh path table 350 shown in a and b of FIG. 11 is obtained by
changing a part of the mesh path table 340 shown in FIG. 8 and adding new
information thereto. Specifically, it is information in which the mesh path
15 expiration time of ExpTime 345 indicated by reference symbol d is set for an
updating expiration time for a mesh path and information of reference symbols e and
fare newly added. Thus, same reference symbols are given to portions of a and b
of FIG. 11 which are the same as those in the mesh path table 340 shown in a and b
of FIG. 8 and a patt of description thereof will be omitted. In addition, a of FIG. 11
20 conesponds to a of FIG. 8, and b of FIG. 11 to b of FIG. 8.
[0159]
As shown in FIG. 11a, the mesh path table 350 is recorded in the memory
150 in a record form. For the sake of facilitating description in the embodiment of
the present technology, an example in which the mesh path table 350 produced by
25 adding new information to the mesh path table 340 shown in FIG. 8 is managed as
one table is shown. The newly added information (the information of the reference
symbols e and f), however, may be managed as a separate table (or in a separate
memory) liom the mesh path table 340.
30
[OI60]
In the ExpTime ((ExpireTime)) 345 of "d" of the Index 346, an updating
expiration time of the mesh path is stored. This updating expiration time of the
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mesh path is decided based on the LifeTime fields 327 and 337 (shown inc and d of
FIG. 4) of a PREQ or a PREP used in generation of the mesh path.
[0 161]
In the LifeTime 351 of"e" of the Index 346, a lifetime of the mesh path is
5 stored. The lifetime of the mesh path is decided based on the LifeTime fields 327
. and 337 (shown inc and d of FIG. 4) of the PREQ or the PREP used in generation of
the mesh path.
[0162]
In the HopCount 352 of "f' of the Index 346, a numerical value indicating
10 the number of hops necessary for delivering a PREP fi·om a transmission source
station (an information processing device which has transmitted the PREP first).
[0163]
[Example in which ExpTime is to set to be shmter than LifeTime]
FIG. 12 is a diagram showing generation and updating examples of the mesh
15 path table 350 retained by each of the information processing devices which
constitute the communication system 200 according to the first embodiment of the
present technology. This generation and updating will be described in detail with
reference to FIGS. 9 and I 0.
[0164]
20 In addition, in this example, an example in which a value of the ExpTime
25
345 ("d" of the Index 346) (updating expiration time of the mesh path) of the mesh
path table 350 shown in FIG. II is set to be shmter than a value of LifeTime ("e" of
the Index 346) (lifetime of the mesh path) is shown.
[0165]
Here, a case in which, when the infonnation processmg device I 00
transmits data to the infmmation processing device 240, the information processing
device I 00 requests generation of a mesh path between the infmmation processing
device 240 will be described with reference to FIGS. 9 and I 0.
[0166]
30 As shown in a of FIG. 9, the infmmation processing'device 100 transmits a
PREQ in which the information processing device 240 is designated in the DestSTA
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field 323 (shown inc of FIG. 4). This PREQ is the same as in the example shown
in a of FIG. 9, and thus description thereof will be omitted here.
[0167]
In addition, when there is no mesh path destined for the information
5 processing device 240, the control unit 140 of the information processing device I 00
generates path information of which the destination is the destination station of the
PREQ. Here, the destination station of the PREQ is the information processing
device of which the identifier is stored in the DestSTA field 323 (shown inc of FIG.
4), which is the information processing device 240 in this example.
10 [0168]
For example, the control unit 140 of the information processing device 100
stores the identifier of the information processing device 240 in the Dest 34 I as
shown in a of FIG. 12. In addition, the control unit 140 of the information
processing device I 00 stores the sum of the current time (transmission time of the
15 PREQ) and the value (Tl) stored in the LifeTime field 327 of the PREQ in the
LifeTime 351 ("e" of the Index 346).
[0169]
In addition, the control unit 140 of the infonnation processing device 100
stores the value obtained by subtracting T2 from the sum of the current time
20 (transmission time of the PREQ) and T1 in the ExpTime 345 ("d" of the Index 346).
[0170]
Here, when the value stored in the LifeTime field 327 of the PREQ is set to
Tl, T2 is a value satisfying the following condition.
Tl>T2>0
25 [0171)
In addition, the control unit 140 of the infonnation processing device 100
stores the value obtained by adding 1 to the value of the SeqNum field 324 of the
PREQ which has been transmitted in the previous round in the SeqNum 344 ("c" of
the Index 346).
30 [0172)
1n addition, the control unit 140 of the information processing device 100
8'I
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leaves each of the NextHop 342 ("a" of the Index 346), the Metric 343 ("b" of the
Index 346), and the HopCount 352 ("f' of the Index 346) undefined.
[0173]
In this manner, the control unit 140 of the information processing device
5 I 00 generates a mesh path destined for the information processing device 240.
[0174]
In addition, as shown in a of FIG. 9, the information processing devices 210,
220, and 230 receive the PREQ transmitted from the information processing device
100. Upon receiving the PREQ as above, the infmmation processing devices 210,
10 220, and 230 generate path information destined for the infmmation processing
device (destined for the information processing device I 00) of which the identifier is
stored in the OrigSTA field 322 of the received PREQ. In other words, the
information processing devices 210, 220, and 230 record the generated path
information in the mesh path table 350 as path information whose destination is the
15 information processing device 100.
[0175]
As shown in b of FIG. 12, the identifier stored in the OrigSTA field 322
(shown inc of FIG. 4) (the identifier of the information processing device 100) is
stored in the Dest 341 of the mesh path table 350 of each of the information
20 processing devices. In addition, the content shown in b of FIG. 12 is stored in each
of the NextHop 342, the Metric 343, and the SeqNum 344 of"a" to "c" of the Index
346 of the mesh path table 350.
[0176]
In addition, each of the information processing devices stores the following
25 value in the LifeTime 351 of "e" of the Index 346 of the mesh path table 350 as
shown in b of FIG. 12.
Reception time ofPREQ+ T1 (value stored in LifeTime field 327 ofPREQ)
[0177]
Here, when the time stored in the LifeTime 351 alTives, each of the
30 information processing devices destroys the mesh path conesponding thereto and
updates the destroyed mesh path. In other words, when the time stored in the
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LifeTime 351 anives, each of the information processing devices destroys each
record corresponding thereto among records of the mesh path table 350, and updates
the destroyed record.
[0178]
5 In addition, each of the information processing devices stores the following
value in the ExpTime 345 of "d" of the Index 346 of the mesh path table 350 as
shown in b of FIG. 12.
Reception time of PREQ+Tl (value stored m LifeTime field 327 of
PREQ)-T2
10 [0179]
In other words, T1-T2 is set in the ExpTime 345 of"d" of the Index 346 of
the mesh path table 350.
[0180]
In addition, when the time stored in the ExpTime 345 arrives, each of the
15 information processing devices updates the mesh path corresponding thereto. In
other words, when the time stored in the ExpTime 345 anives, each of the
information processing devices updates each record corresponding thereto among the
records of the mesh path table 350.
[0 181]
20 In addition, each of the infmmation processing devices stores the value
stored in the HopCount field 325 of the PREQ in the HopCount 352 of "f' of the
Index 346 of the mesh path table 350 as shown in b of FIG. 12.
[0182]
In this mannet~ each of the relay stations (the information processmg
25 devices 210, 220, and 230) generates a mesh path destined for the information
processing device 100.
[0183]
In addition, each of the information processing devices 210, 220, and 230
which have received the PREQ transfers the received PREQ as shown in b of FIG. 9
30 because the identifier in the DestSTA field 323 of the received PREQ is not its own
identifier. Since this PREQ to be transferred is the same as in the example shown in
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b of FIG. 9, description thereof is omitted here.
[0184]
Upon rece1vmg the PREQ transferred as above, for example, the
information processing device 240 generates path information destined for the
5 information processing device (destined for the information processing device 1 00)
of which the identifier is stored in the OrigSTA field 322 of the received PREQ in the
above-described procedure. In other words, the information processing device 240
records the generated path information in the mesh path table 350 as path
information whose destination is the information processing device 100.
10 [0185]
Here, the information processing device 240 receives the PREQ fi'Om each
of the information processing devices 220 and 230 as shown in b of FIG. 9. Upon
receiving the PREQs from the plurality of information processing devices, the
information processing device 240 selects a path with a low path metric value as a
15 valid mesh path, and discards the PREQ with a high path metric value.
[0186]
In this example, the case in which the path metric value of the PREQ
transferred from the information processing device 230 is lower than the path metric
value of the PREQ transferred from the information processing device 220 is
20 assumed as described above. Thus, the information processing device 240
generates a mesh path for which the NextHop 342 is set to the infonnation
processing device 230 as a mesh path destined for the information processing device
25
100.
[0187]
In addition, since the information processing device 240 is designated as the
DestSTA field 323 of the received PREQ, the device itself generates a PREP to
respond to the PREQ. Then, the information processing device 240 transmits the
generated PREP by designating the NextHop destined for the OrigSTA field 322 of
the PREQ as a receiving station as shown in a of FIG. I 0. Since the PREP
30 generated in this case as a transmission target is the same as in the example shown in
a of FIG. I 0, description thereof is omitted here.
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[0188]
In addition, the identifier stored in the DestSTAfield 323 (shown inc of FIG.
4) (the identifier of the infonnation processing device 100) is stored in the Dest 341
of the mesh path table 350 of the information processing device 240. In addition,
5 the content shown in c of FIG. 12 is stored in each of the NextHop 342, the Metric
343, and the SeqNum344 of"a" to "c" of the Index 346 of the mesh path table 350.
[0189]
In addition, the information processing device 240 stores the following
value in the LifeTime 351 of "e" of the Index 346 of the mesh path table 350 as
10 shown inc of FIG. 12.
Reception time ofPREQ+ T1 (value stored in LifeTime field 327 ofPREQ)
[0190]
In addition, the information processing device 240 stores the following
value in the ExpTime 345 of "d" of the Index 346 of the mesh path table 350 as
15 shown inc of FIG. 12.
Reception time of PREQ+Tl (value stored in LifeTime field 327 of
PREQ)~T2
[0 191]
In addition, when the time stored in the LifeTime 351 arrives, the
20 information processing device 240 destroys the mesh path corresponding thereto and
updates the destroyed mesh path as described above. In addition, when the time
stored in the ExpTime 345 arrives, the information processing device 240 updates the
mesh path corresponding thereto.
[0192]
25 In addition, the infotmation processing device 240 stores the value stored in
the HopCount field 325 of the PREQ in the HopCount 352 of"f' of the Index 346 of
the mesh path table 350 as shown inc of FIG. 12.
[0193]
In addition, the information processing device 240 transmits the generated
30 PREP by designating the NextHop 342 destined for the OrigSTA field 322 of the
PREQ as a receiving station. Since the PREP generated in this case as a
>1
B
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transmission target is the same as in the example shown in a of FIG. 10, description
thereof is omitted here.
[0194]
In addition, since generation of a mesh path of each of the infonnation
5 processing devices which have received the PREP is the same as in the example
shown in a and b of FIG. 10 except for the point that the content of "d" to "f" of the
Index 346 of the mesh path table 350 is different, description thereof is omitted here.
In addition, since the content of "d" to "f" of the Index 346 of the mesh path table
350 is the same as in the example of each of the information processing devices
10 which has received the above-described PREQ, description thereof is omitted here.
[0195]
Each of the information processing devices updates the content of the mesh
path table 350 as described above. In addition, when the time stored in the
LifeTime 351 an·ives, each of the information processing devices destroys the mesh
15 path corresponding thereto and updates the destroyed mesh path. However, at the
timing at which the earlier time than the time stored in the LifeTime 351 (the time
stored in the ExpTime 345) has arrived, each of the information processing devices
can update the mesh path corresponding thereto.
20
[0196]
In other words, before the path information regarding the mesh path
(communication path) set through exchange of the signals such as the PREQ and the
PREP is destroyed, the control unit 140 performs control to update the path
information. Specifically, the control unit 140 decides an effective time (expiration
time) for specifying a time at which the path information is destroyed based on
25 expiration time information included in the signals such as the PREQ and the PREP.
In addition, based on the expiration time information included in the signals such as
the PREQ and the PREP, the control unit 140 decides an updating time (updating
expiration time) for specifying a time during which the path information is updated
to be a time shmier than the effective time.
30 [0197]
Accordingly, when a multi-hop connnunication path is generated through
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the exchange of the signals such as the PREQ and PREP, updating of a mesh path
that has already been generated (path information) can be started before the mesh
path is destroyed.
[0198]
5 [Example in which ExpTime is changed according to a position on a path]
The example in which ExpTime is set to be shmter than LifeTime has been
shown above. Here, an example in which ExpTime is changed according to a
position on a path will be shown. For example, an interval of updating times of a
transmission source station which has transmitted a path setting request (for example,
10 a PREQ) first is set to be the shortest, and an interval of updating times of a
destination station of the path setting request is set to be the second shortest.
Furthermore, intervals of updating times of relay stations are set to be shorter
according to their positions in the order of hopping from the transmission source
station.
15 [0199]
It should be noted that, in this example, a part of the example in which the
above-described ExpTime is set to be shorter than LifeTime is modified, and a part
of the mesh path table 350 to be generated (or to be updated) is different.
Specifically, the generated content (or updated content) of the ExpTime 345 ("d" of
20 the Index 346) of the mesh path table 350 is different. Thus, the difference will be
mainly described below, and a patt of description regarding common pmtions to the
above-described example will be omitted.
[0200]
FIGS. 13 and 14 are diagrams showing generation and updating examples of
25 the mesh path table 350 retained by each of the information processing devices
which constitute the communication system 200 according to the first embodiment of
the present technology. It should be noted that a of FIG. 13 is the same as the
example shown in a of FIG 12.
[0201]
30 Each of relay stations (the information processing devices 210, 220, and
230) stores the next value in the ExpTime 345 of "d" of the Index 346 of the mesh
5
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path table 350 as shown in b of FIG 13.
Reception time of PREQ+ Tl (value stored m LifeTime field 327 of
PREQ)-T5
[0202]
Here, when the value stored in the LifeTime field 327 of the PREQ is set to
Tl, T5 is a value which satisfies the following condition.
Tl > T2 > T3 > T4 ::>: T5 > 0
[0203]
It should be noted that T3 and T4 will be shown below.
10 [0204]
15
As described above, each of the relay stations (the information processing
devices 210, 220, and 230) generates a mesh path destined for the information
processing device 100.
[0205]
In addition, the destination station (the information processing device 240)
stores the following value in the ExpTime 345 of "d" of the Index 346 of the mesh
path table 350.
Reception time of PREQ+ Tl (value stored in LifeTime field 327 of
PREQ)-TI
20 [0206]
Here, when the value stored in the LifeTime field 327 of the PREQ is set to
Tl, T3 is a value which satisfies the above condition (Tl > T2 > T3 > T4 ::>: T5 > 0).
[0207]
In addition, the information processing device 240 transmits the generated
25 PREP by designating the NextHop 342 destined for the OrigSTA field 322 of the
PREQ as a receiving station. Since the PREP generated to be transmitted in this
case is the same as in the example shown in a of FIG. 10, description thereof is
omitted here.
30
[0208]
In addition, generation of a mesh path of the relay station (the infonnation
processing device 230) which has received the PREP fi-om the information
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processing device 240 is the same as in the example shown in a and b of FIG. 10
except for the point that the content of the ExpTime 345 ("d" of the Index 346) is
different.
[0209]
5 Specifically, the-relay station (the information processing device 230) stores
the following value in the ExpTime 345 of "d" of the Index 346 of the mesh path
table 3 50 as shown in FIG. 14.
Reception time of PREP+Tl (value stored m LifeTime field 337 of
PREP)-T4
10 [0210]
Here, when the value stored in the LifeTime field 337 of the PREQ is
assumed to be Tl, T4 is a value satisfying the above-described condition (Tl > T2 >
T3 > T4 ~ T5 > 0) and the following conditions.
T4 = T3-T5xHopCount (if (T3-T5x(PREP HopCount+ 1)) > T5)
15 T4 =T5 (if(T3-T5x(PREP HopCount+l)) :-:; T5)
[0211]
As described above, the control unit 140 changes an updating time
(updating period) of a mesh path (communication path) based on the position of the
infotmation processing device 100 on the mesh path (communication path). In this
20 case, when the information processing device 100 is an information processing
device located at an end of the mesh path (communication path), the control unit 140
sets the updating time (updating expiration time) to be shorter than that of another
information processing device on the mesh path (communication path). Specifically,
the control unit 140 sets the updating time (updating expiration time) to be the
25 shortest when. the information processing device I 00 is the transmission source
station, and sets the updating time (updating expiration time) to be the second
shortest when the information processing device 1 00 is the destination station.
[0212]
In this manner, for example, the interval of the updating time of the
30 transmission source station which has transmitted the path setting request (for
example, a PREQ) first is set to be the shortest, and the interval of the updating time
SP353494WOOO
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of the destination station of the path setting request is set to be the second shortest.
In addition, for example, the interval of the updating time of the relay stations can be
set to be shorter according to the orders of hops of the relay stations from the
transmission source station.
5 [0213]
[Example in which LifeTime is changed according to the total number of hops]
The example in which ExpTime is changed according to a position on a path
has been shown above. Here, an example in which LifeTime is changed according
to the total number of hops will be shown.
10 [0214]
It should be noted that, in this example, a part of the example in which the
above-described ExpTime is set to be shmter than LifeTime is modified, and a pmt
of the mesh path table 350 to be generated (or to be updated) is different.
Specifically, the content of generation (or content of updating) of the ExpTime 345
15 ("d" of the Index 346) and the LifeTime 351 ("e" of the Index 346) of the mesh path
table 350 is different. Thus, the differences will be mainly described below, and a
patt of description regarding common portions to the above-described example will
be omitted.
20
25
[0215]
FIGS. 15 and 16 are diagrams showing generation and updating examples of
the mesh path table 350 retained by each of the information processing devices
which constitute the communication system 200 according to the first embodiment of
the present technology.
[0216]
As shown in a of FIG. 9, the information processing device 100 transmits
the PREQ for which the information processing device 240 is designated in the
DestSTA field 323 (shown inc of FIG. 4). In this case, when there is no mesh path
destined for the infmmation processing device 240, the control unit 140 of the
information processing device 100 generates path information of which the
30 destination is set to the destination station of the PREQ.
[0217]
5
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As shown in a of FIG. 15, for example, the control unit 140 of the
information processing device 100 stores the sum of the current time (transmission
time of the PREQ) and T6 in the LifeTime 351 ("e" of the Index 346).
[0218]
In addition, the control unit 140 of the information processing device 100
stores the value obtained by subtracting T2 from the sum of the current time
(transmission time of the PREQ) and T6 in the ExpTime 345 ("d" of the Index 346).
[0219]
Here, when the value stored in the LifeTime field 327 of the PREQ rs
10 assumed to be T1, T6 is the value satisfying the following condition.
T6=Tl>T2>0
[0220]
In this manner, the control unit 140 of the information processing device
100 generates a mesh path destined for the information processing device 240.
15 [0221]
In addition, when there is a mesh path destined for the infonnation
processing device 240, the value ofT6 may be changed according to the value of the
HopCount 352 as shown in the following Expression 2.
T6 = T5x(HopCount+ 1) ... Expression 2
20 [0222]
In this case, in order to prevent the value of ExpTime 345 from being
excessively short, an upper limit may be set for the value ofT6.
[0223]
In this manner, the control unit 140 of the information processing device
25 I 00 updates the mesh path destined for the information processing device 240.
30
[0224]
Each of the relay stations (information processing devices 210, 220, and
230) stores the following value in the ExpTime 345 of "d" of the Index 346 of the
mesh path table 350 as shown in b of FIG. 15.
Reception time of PREQ+ T1 (value stored 111 LifeTime field 327 of
PREQ)-T5
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[0225]
Here, when the value stored in the LifeTime field 327 of the PREQ IS
assumed to be Tl, T5 is a value satisfying the following condition.
T6 > T2 > T3 > T4 2: T5 > 0
5 [0226]
10
In this manner, each of the relay stations (infonnation processing devices
210, 220, and 230) generates a mesh path destined for the information processing
device 100.
[0227]
In addition, the destination station (information processing device 240)
stores the following value in the ExpTime 345 of "d" of the Index 346 of the mesh
path table 350.
Reception time of PREQ+ Tl (value stored in the LifeTime field 327 of
PREQ)-T3
15 [0228]
Here, T3 may be changed according to the value ofT6. For example, T3 =
T7 (a constant) is possible.
[0229]
In addition, the information processing device 240 transmits the generated
20 PREP by designating the NextHop 342 destined for the OrigSTA field 322 of the
PREQ as a receiving station. Since the PREP generated to be transmitted in this
case is the same as in the example shown in a of FIG. 10, description thereof is
omitted here.
25
[0230]
In addition, generation of a mesh path by a relay station (information
processing device 230) which has received the PREP Ji'mn the infmmation
processing device 240 is the same as in the example shown in a and b of FIG. 10
except for the point that the content of the ExpTime 345 ("d" of the Index 346) is
different.
30 [0231]
Specifically, the relay station (information processing device 230) stores the
SP353494WOOO
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following value in the ExpTime 345 of "d" of the Index 346 of the mesh path table
350 as shown in FIG. 16.
Reception time of PREP+Tl (value stored in the LifeTime field 337 of the
PREP)-T4
5 [0232]
Here, T4 is set to be a value satisfying the above-described condition (T6 >
T2 > T3 > T4 2 T5 > 0) and the following conditions.
T4 = T3-T5xHopCount (if (T3-T5x(PREP HopCount+ 1 )) > T5)
T4 = T5 (if (T3-T5x(PREP HopCount+ 1 )) ::; T5)
10 [0233]
15
In this mannet~ the control unit 140 changes the lifetime (expiration time) of
the mesh path (communication path) based on the number of relay stations.
[0234]
[Example in which the LifeTime is changed according to a situation of a path]
The example in which the ExpTime is changed has been shown above.
Here, an example in which the LifeTime is changed according to a situation of a path
will be shown. When a situation of a path is not changed (for example, adjacent
similar information processing devices are consecutively selected), for example, a
value of the LifeTime can be increased (the expiration time can be extended).
20 [0235]
It should be noted that, in this example, a part of the example in which the
above-described ExpTime is set to be shmter than LifeTime is modified, and a part
of the mesh path table 350 to be generated (or to be updated) is different. Thus, the
differences will be mainly described below, and a part of description regarding
25 common portions to the above-described example will be omitted.
[0236]
[Configuration example of a mesh path table]
FIG. 17 is a diagram schematically showing still another example of the
mesh path table (mesh path table 360) retained by each of the information processing
30 devices which constitute the communication system 200 according to the first
embodiment of the present teclmology. Since a configuration of the mesh path table
SP353494WOOO
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360 has the same fmm as in the example shown in a of FIG. II, illustration thereof is
omitted here.
[0237]
In addition, in FIG. 17, the Index 346, the data name 347, and the meaning
5 348 are shown as examples of the content of the mesh path table 360. The mesh
path table 360 shown in FIG. 17 is obtained by adding new information to the mesh
path table 350 shown in FIG. II. Specifically, information of reference symbols a-!
to a-9 is newly added information. Thus, in FIG. 17, the same reference symbols
are given to portions common to those of the mesh path table 3 50 shown in FIG. 11
10 and part of description thereof will be omitted. Furthermore, FIG. 17 cmTesponds
to b ofFIG. II.
[0238]
In a NextHop-1 (361) of "a-I" of the Index 346, the identifier of the
NextHop 342 of "a" of the Index 346 stored just before is stored. In other words, in
15 the NextHop-1 (361) of"a-1" of the Index 346, the identifier of the NextHop 342 of
1 previous communication is stored.
[0239]
Likewise in a NextHop-2 (362) to a NextHop-9 (369) of "a-2" to "a-9" of
the Index 346, the identifiers of the NextHop 342 of "a" of the Index 346 previously
20 stored are stored. In other words, in the NextHop-2 (362) to the NextHop-9 (369)
of "a-2" to "a-9" of the Index 346, the identifiers of the NextHop 342 of 2 to 9
previous communications are stored.
[0240]
It should be noted that the initial values of the NextHop-1 (361) to the
25 NextHop-9 (369) of"a-1" to "a-9" of the Index 346 are set to 0.
[0241]
[Generation and updating examples of a mesh path table]
FIG. 18 is a diagram showing generation and updating examples of the mesh
path table 350 retained by each of the information processing devices which
30 constitute the communication system 200 according to the first embodiment of the
present technology.
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[0242]
As shown in a of FIG. 9, the information processing device 100 transmits
the PREQ by designating the infonnation processing device 240 in the DestSTA field
323 (shown inc of FIG. 4). In this case, when there is no mesh path destined for the
5 information processing device 240, the control unit 140 of the information
processing device 100 generates path information of which the destination is set to
the destination station of the PREQ.
[0243]
Here, when there is a mesh path destined for the information processing
10 device 240, the control unit 140 of the information processing device 100 extracts the
same identifiers as those stored in the current NextHop 342 from the identifiers
stored in the past NextHop 342 and counts the number. In other words, the control
unit 140 of the information processing device 1 00 compares each of the identifiers
stored in the NextHop-1 (361) to the NextHop-9 (369) to the identifier stored in the
15 NextHop 342. Then, the control unit 140 of the information processing device I 00
extracts identifiers which coincide with each other fi·om the identifiers and counts the
number.
[0244]
Subsequently, the control unit 140 of the information processing device I 00
20 sets a value no which relates to the expiration time to be stored in the LifeTime 351
according to the number of coinciding identifiers. For example, when the number
of coinciding identifiers is 3 or lower, no= n (value stored in the LifeTime field
337 of the PREP) is set. In addition, when the number of coinciding identifiers is 4
or higher and 7 or lower, no = nx2 is set. In addition, when the number of
25 coinciding identifiers is 8 or higher, n 0 = n x3 is set. n 0, however, is set to be a
value satisfying the following condition.
nO>T2>0
[0245]
The control unit 140 of the infmmation processing device 100, for example,
30 stores the sum of tl1e cunent time (transmission time of tl1e PREQ) and T10 in the
LifeTime 351 ("e" of the Index 346) as shown in a of FIG. 18.
>I
B
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[0246]
In addition, the control unit 140 of the information processing device I 00
stores the value obtained by subtracting T2 from the sum of the current time
(transmission time of the PREQ) and TIO in the ExpTime 345 ("d" of the Index 346).
5 [0247]
It should be noted that, although the example in which the identifier of the
NextHop 342 of the 9 previous communications is retained has been shown in this
example, the identifiers of the NextHop 342 of a value other than the 9 previous
communications (8 prevwus communications or less and 10 prevwus
10 communications or more) may be retained and used.
[0248]
In addition, although the example in which Tl 0 is set based on the number
of coinciding identifiers among those of the NextHop 342 of a plurality of previous
communications has been shown in this example, TIO may be set based on the
15 number of consecutive identifiers among those of the NextHop 342 of the plurality of
previous communications.
[0249]
In this manner, the control unit 140 of the information processing device
I 00 updates the mesh path destined for the information processing device 240.
20 [0250]
It should be noted that b and c of FIG. 18 are the same as the example
shown in b and c of FIG. 15 except for the point that the conditions for T3 to T5 are
different. In addition, the content of updating the relay station which has received
the PREP (FIG. 16) is the same as the example shown in FIG. 16 except for the point
25 that the condition ofT4 is different. Thus, description thereof is omitted here.
[0251]
It should be noted that T3 to T5 are set to have values satisfying the
follo\\~ng condition.
TIO>T2 > T3 >T42:T5 > 0
30 [0252]
As described above, when the same communication path is consecutively
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selected as a mesh path (communication path) updated through exchange of signals
such as the PREQ and the like, the control unit 140 lengthens the effective time
(expiration time) and updating time (updating expiration time). Likewise, when a
rate of selection of the same mesh path (communication path) is higher than a
5 predetennined value, the control unit 140 lengthens the effective time (expiration
time) and updating time (updating expiration time).
[0253]
It should be noted that the control unit 140 of the information processing
device 100 may transmit a PREQ by setting the value of the LifeTime field 327 to be
10 T1 0. In this case, the updating expiration time and expiration time of a relay station
and the destination station of the PREQ are decided with reference to Tl 0.
[0254]
[Example in which the LifeTime is changed according to a situation of a link]
The example in which the LifeTime is changed according to a situation of a
15 path has been shown above. Here, an example in which the LifeTime is changed
according to a situation of a link will be shown. When a situation of a link is good
(for example, the electric field intensity of an information processing device
designated as a next hop destination is higher than a threshold value), for example,
the value of the LifeTime can be set to be high (the expiration time can be delayed).
20 In addition, when a situation of a link is bad (for example, the electric field intensity
of an information processing device designated as a next hop destination is equal to
or lower than the threshold value), for example, the value of the LifeTime can be set
to be low (the expiration time can be advanced).
25
[0255]
It should be noted that, in tllis example, a part of the example in which the
above-described ExpTime is set to be shmter than LifeTime is modified, and a part
of the mesh path table 350 to be generated (or to be updated) is different. Thus, the
differences will be mainly described, and a patt of description regarding common
portions to the above-described example will be omitted.
30 [0256]
In addition, since the content of updating is tl1e same as that of FIG. 18, it
>I
8
SP353494WOOO
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will be described with reference to FIG. 18 in this example.
[0257]
As shown in a of FIG. 9, the information processing device 100 transmits
the PREQ by designating the information processing device 240 in the DestSTA field
5 323 (shown inc of FIG. 4). In this case, when there is no mesh path destined for the
information processing device 240, the control unit 140 of the information
processing device I 00 generates path information of which the destination is set to
the destination station of the PREQ as described above.
10
[0258]
Here, when there is a mesh path destined for the information processing
device 240, the control unit 140 of the information processing device 100 sets a value
of the LifeTime according to the value of the electric field intensity of the
information processing device of the NextHop 342. Here, the electric field intensity
is, for example, a Received Signal Strength Indicator (RSS1).
15 [0259]
When the RSSI is lower than -70 dBm, for example, the control unit 140 of
the information processing device I 00 sets T1 0 = T1 x0.8. In addition, when the
RSSI is -70 dBm or greater and lower than -60 dBm, the control unit 140 of the
information processing device 100 sets Tl 0 = Tl. Fmthermore, when the RSSI is
20 -60 dBm or greater and lower than -40 dBm, the control unit 140 of the information
processing device 100 sets T1 0 = T1 x2. In addition, when the RSSI is -40 dBm or
greater, the control unit 140 of the information processing device 100 sets T1 0 =
Tlx3.
[0260]
25 In other words, T1 0 is set as follows.
TIO = Tlx0.8 ifRSSI < -70 dBm
Tl 0 = TI if-70 dBm s; RSSI < -60 dBm
TIO = Tlx2 if -60 dBm s; RSSI < -40 dBm
T1 0 = Tlx3 if -40 dBm s; RSSI
30 [0261]
Here, T1 0 is set to be a value satisfying the following condition.
SP 353494 WOOO
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TIO>T2>0
[0262]
It should be noted that, when there is no mesh path destined for the
information processing device 240, the control unit 140 of the information
5 processing device·) 00 may set TIO = Tl.
[0263]
The control unit 140 of the infonnation processing device 100 stores, for
example, the sum of the current time (transmission time of the PREQ) and TIO in the
LifeTime 351 ("e" of the Index 346) as shown in a of FIG. 18.
10 [0264]
15
In addition, the control unit 140 of the infonnation processing device 100
stores the value obtained by subtracting T2 from the sum of the current time
(transmission time of the PREQ) and Tl 0 in the ExpTime 345 ("d" of the Index 346).
[0265]
In this manne1; the control unit 140 of the infmmation processing device
100 generates or updates the mesh path destined for the infonnation processing
device 240.
[0266]
It should be noted that generation or updating of a mesh path of a relay
20 station and the destination station of the PREQ and a relay station of the PREP is the
same as in the example in which the LifeTime is changed according to a situation of
a path. Thus, description thereof is omitted here.
[0267]
As described above, when the electric field intensity of an information
25 processing device set as a next transmission destination on a mesh path
(communication path) is set to be higher than the tlu-eshold value, the conti·ol unit
140 lengthens the effective time (expiration time) and the updating time (updating
expiration time). On the other hand, when the electric field intensity of an
information processing device set as a next transmission destination is set to be lower
30 than the threshold value, the confi·ol unit 140 shmtens the effective time (expiration
time) and the updating time (updating expiration time).
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[0268]
[Example in which the LifeTime is changed according to a movement state of an
information processing device]
The examples in which the LifeTime is changed according to situations of a
5 path and a link have been described above. An example in which the LifeTime is
changed according to a movement state of an information processing device will be
shown here. In a state in which an information processing device is moving, for
example, a value of the LifeTime is set to be small (the expiration time is advanced).
10
[0269]
It should be noted that, in this example, a pmt of the example in which the
above-described ExpTime is set to be shmter than the LifeTime is modified, and a
part of the mesh path table 350 to be generated (or to be updated) is different. Thus,
the differences will be mainly described below, and a part of description regarding
common pmtions to the above-described example will be omitted.
15 [0270]
In addition, since the content of updating is the same as in FIG. 18, it will be
described with reference to FIG. 18 in this example.
[0271]
As shown in a of FIG. 9, the information processing device I 00 transmits
20 the PREQ by designating the information processing device 240 in the DestSTA field
323 (shown inc of FIG. 4). In this case, when there is no mesh path destined for the
information processing device 240, the control unit 140 of the information
processing device I 00 generates path infmmation of which the destination is set to
the destination station of the PREQ as described above. In addition, when there is a
25 mesh path destined for the information processing device 240, the control unit 140 of
the information processing device I 00 updates the path information of which the
destination is set to the destination station of the PREQ as described above.
[0272]
Here, the control unit 140 of the infommtion processmg device I 00
30 determines whether or not movement of the infmmation processing device I 00 has
been detected. The control unit 140 of the information processing device 100 can
"8
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detect movement of the information processing device 1 00 based on movement
information output fi·om, for example, the movement detection unit 171. In
addition, the control unit 140 of the information processing device 100 can detect
movement of the information processing device 100 based on, for example, a
5 movement distance of the information processing device 100 computed by the
movement detection unit 171. It should be noted that the control unit 140 of the
infmmation processing device 100 may detect movement of the information
processing device 100 based on, for example, a change of an electric field intensity
(for example, the RSSI). The control unit 140 of the information processing device
10 100 determines, for example, whether or not a change of the electric field intensity (a
change per unit time) acquired by the information processing device 100 is equal to
or greater than a predetermined value, and can detect movement of the information
processing device 100 based on the determination result.
15
[0273]
Then, the control unit 140 of the information processing device 1 00 sets T1 0
Tlx0.8 when movement of the information processing device 100 has been
detected. In addition, when no movement of the information processing device 100
has been detected (i.e., movement of the information processing device 100 stops),
the control unit 140 of the information processing device 100 sets TlO = Tl. It
20 should be noted that Tl 0 is set to be a value satisfying the following condition.
TlO>T2>0
[0274]
For example, the control unit 140 of the information processing device 100
stores the sum of the cmTent time (transmission time of the PREQ) and T1 0 in the
25 LifeTime 351 ("e" of the Index 346) as shown in a of FIG. 18.
[0275]
In addition, the control unit 140 of the information processing device 100
stores the value obtained by subtracting T2 from the sum of the current time
(transmission time of the PREQ) and TlO in the ExpTime 345 ("d" of the Index 346).
30 [0276]
In this manner, the control unit 140 of the information processing device
SP353494WOOO
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I 00 generates or updates the mesh path destined for the information processing
device 240.
[0277]
It should be noted that the value of T1 0 may be set more finely according to
5 a movement speed or a inovement distance of the information processing device I 00.
[0278]
It should be noted that generation or updating of a mesh path of a relay
station and the destination station of the PREQ and a relay station of the PREP is the
same as in the example in which the Life Time is changed according to a situation of
10 a path. Thus, description thereof is omitted here.
[0279]
As described above, when the information processing device I 00 is moving,
the control unit 140 shortens the effective time (expiration time) and updating time
(updating expiration time).
15 [0280]
[Example in which the LifeTime is changed according to presence or absence of a
path candidate]
The examples in which the LifeTime is changed according to situations of a
path and a link and a movement state of the information processing device have been
20 shown above. Here, an example in which the LifeTime is changed according to
presence or absence of a path candidate of an infonnation processing device will be
shown. When an information processing device is assumed to serve as a path
candidate, for example, a value of the LifeTime is set to decrease (the expiration time
is advanced). Here, the case in which an information processing device is assumed
25 to serve as a path candidate is a case in which, for example, the electric field
intensity of another information processing device (an adjacent station) which is not
designated as a next hop destination is higher than a threshold value.
[0281 l
It should be noted that, in this example, a part of the example in which the
30 above-described ExpTime is set to be shorter than the LifeTime is modified, and a
part of the mesh path table 350 to be generated (or to be updated) is different. Thus,
SP353494WOOO
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the differences will be mainly described below, and a pmt of description regarding
common portions to the above-described example will be omitted.
[0282]
In addition, since the content of updating is the same as in FIG. 18, it will be
5 described with reference to FIG. 18 in this example.
[0283]
As shown in a of FIG. 9, the information processing device 100 transmits
the PREQ by designating the information processing device 240 in the DestSTA field
323 (shown inc of FIG. 4). In this case, when there is no mesh path destined for the
10 infmmation processing device 240, the control unit 140 of the infmmation
processing device 100 generates path information of which the destination is set to
the destination station of the PREQ as described above. In addition, when there is a
mesh path destined for the information processing device 240, the control unit 140 of
the information processing device 100 updates the path information of which the
15 destination is set to the destination station of the PREQ as described above.
[0284]
Here, the control unit 140 of the information processmg device 1 00
determines, for example, whether or not the electric field intensity of an information
processing device (an adjacent station) that is not designated in the NextHop 342 is
20 higher than a till'eshold value. For example, the control unit 140 of the information
processing device 100 determines whether or not the electric field intensity (RSSI) of
an information processing device whose identifier is not stored in the NextHop 342 is
equal to or higher than the threshold value ( -60 dBm). Then, when the electric
field intensity (RSSI) of the information processing device is less than the threshold
25 value ( -60 dBm), TlO = T1 is set. In addition, when the electric field intensity
(RSSI) of the information processing device is equal to or higher than the threshold
value (-60 dBm), TlO = Tlx0.8 is set.
[0285]
In other words, T1 0 is set as follows.
30 TlO=Tl ifRSSI < -60 dBm
TlO = Tlx0.8 if -60 dBm s RSSI
5
[0286]
[0287]
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Here, T! 0 is set to be a value satisfYing the following condition.
TIO>T2>0
It should be noted that, in this example, the example in which the LifeTime
1s changed using the electric field intensity of an information processing device
(adjacent station) which is not designated in the NextHop 342 is shown; however, the
LifeTime may be changed using the difference between the electric field intensity of
the information processing device of the NextHop 342.
10 [0288]
For example, the difference between the electric field intensity of an
infonnation processing device that is not the NextHop 342 (RSSI OTHERS) and the
electric field intensity of the infonnation processing device of the NextHop (RSSI
NEXT) is computed. Then, based on whether or not the difference is greater than a
15 threshold value (for example, 20 dBm), the LifeTime may be changed. In other
words, the LifeTime can be changed based on whether or not the eleclxic field
intensity of an infmmation processing device that is not the NextHop 342 (RSSI
OTHERS)-the electric field intensity of the information processing device of the
NextHop 342 (RSSI NEXT)> 20 dBm is satisfied.
20 [0289]
25
For example, the control unit 140 of the information processing device 100
stores the sum of the cunent time (transmission time of the PREQ) and Tl 0 in the
LifeTime 351 ("e" of the Index 346) as shown in a of FIG. 18.
[0290]
In addition, the control unit 140 of the information processing device 100
stores the value obtained by subtracting T2 from the sum of the current time
(transmission time of the PREQ) and TIO in the ExpTime 345 ("d" of the Index 346).
[0291]
In this manner, the control unit 140 of the information processing device
30 I 00 generates or updates the mesh path destined for the information processing
device 240.
SP353494WOOO
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[0292]
It should be noted that the value ofTlO may be set more finely.
[0293]
In addition, generation or updating of a mesh path of a relay station and the
5 destination station of the PREQ and a relay station of the PREP is the same as in the
example in which the LifeTime is changed according to a situation of a path. Thus,
description thereof is omitted here.
[0294]
As described above, when the electric field intensity of an information
10 processing device which is not designated as the next transmission destination on a
mesh path (communication path) is greater than the threshold value, the control unit
140 shortens the effective time (expiration time) and updating time (updating
expiration time).
[0295]
15 [Example of a path search start timing according to a situation of a link]
20
Here, an example in which a path search start timing is set according to a
situation of a link will be shown. When a situation of a link is bad, for example, it
is controlled to stmt path search.
[0296]
For example, the control unit 140 of the information processing device 100
monitors packet loss of each adjacent station (each of the information processing
devices (for example, the information processing devices 210, 220, and 230 shown in
FIG. I) which is directly linked to the information processing device I 00). Then,
the control unit !40 of the information processing device 100 determines whether or
25 not there is one with a packet error rate exceeding a threshold value (one with the
number of packet losses exceeding the threshold value) among the information
processing devices whose identifiers me stored in the NextHop 342. As a result of
the determination, when there is an information processing device with a packet error
rate exceeding the threshold value, the control unit 140 of the information processing
30 device 100 starts updating of a mesh path of another information processing device
passing through the foregoing information processing device. In other words, the
SP353494WOOO
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setting of the path of the other information processing device passing through the
foregoing information processing device is updated.
[0297]
In this manner, when there is an information processing device with the
5 number of packet losses greater than the threshold value among information
processing devices designated as the next transmission destinations on a mesh path
(communication path), the control unit 140 transmits a signal (PREQ) for updating
the communication path. This signal is transmitted to another information
processing device (destination of the mesh path) on the mesh path (communication
10 path) including the foregoing information processing device.
[0298]
[Example of a path search statt timing when a new link has been established]
Here, an example in which a path search statt timing is set when a new link
has been established will be shown.
15 [0299]
For example, when a new link has been established with an adjacent
information processing device, the control unit 140 of the infmmation processing
device 100 starts updating of a mesh path to the foregoing infmmation processing
device. In other words, a setting of the path to the information processing device is
20 started.
[0300]
In this case, the control unit 140 of the information processing device 100
may set, for example, a random delay time before updating of the mesh path is
started (before a search for the path is slatted). Then, when the setting of the path is
25 to be started, the control unit 140 of the information processing device I 00 starts the
setting of the path after the set random delay time elapses. Accordingly, the
information processing devices can be caused not to simultaneously start updating of
the mesh path.
30
[0301]
In this manner, when there is an information processing device of which a
new link has been established with the information processing device roo, the
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control unit 140 transmits a signal for updating the mesh path (communication path)
to another information processing device on the mesh path (communication path)
including the foregoing information processing device. In this case, the control unit
140 transmits the signal for updating the mesh path (communication path) by setting
5 a random delay time.
[0302]
[Example of a path search start timing when a link is discmmected]
Here, an example in which a path search start timing is set when a link is
disconnected will be shown.
10 [0303]
For example, when a link with an information processing device whose
identifier is stored in the NextHop 342 is disconnected, updating of a mesh path to
another information processing device passing through the foregoing information
processing device is started up. In other words, a setting of the path to the other
15 information processing device passing through the foregoing infmmation processing
device is slatted.
[0304]
As described above, when a link with an information processing device that
IS the next transmission destination of a mesh path (communication path) is
20 disconnected, the control unit 140 transmits a signal for updating the mesh path
(communication path) to atlother information processing device on the mesh path
(communication path) including the foregoing infom1ation processing device.
[0305]
[Operation example of an information processing device]
25 FIGS. 19 to 24 m·e flowcharts showing an example of the procedure of
signal processing by the information processing device 100 according to the first
embodiment of the present technology. In FIGS. 19 and 24, a signal processing
example corresponding to the example in which the ExpTime is changed according
to a position on a path (shown in FIGS. 13 and 14) is shown.
30 [0306]
First, the control unit 140 determines whether or not there is a transmission
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request for a PREQ (Step SSO 1 ). When there is a transmission request for a PREQ
(Step S801), the control unit 140 creates a mesh path table for the destination station
of the PREQ (Step S802), and proceeds to Step S805.
[0307]
When there is no transmission request for a PREQ (Step SSO 1 ), the control
unit 140 determines whether or not there is a mesh path table in which an updating
expiration time stored in the ExpTime 345 is past the current time (Step S803).
When there is a mesh path table in which the updating expiration time is past the
current time (Step S803), the control unit 140 updates the mesh path table for the
10 destination station (Step S804). Subsequently, the control unit 140 creates a PREQ
and transmits the signal to the destination station (Step S805).
[0308)
When there is no mesh path table in which the updating expiration time is
past the current time (Step S803), the control unit 140 determines whether or not
15 there is a mesh path table in which the expiration time stored in the LifeTime 351 is
past the current time (Step S806). When there is a mesh path table in which the
expiration time is past the current time (Step S806), the control unit 140 dete1mines
whether or not the ExpTime 345 of the mesh path table is undefined (Step S807).
[0309]
20
25
Then, when the ExpTime 345 of the mesh path table is undefined (Step
S807), the control unit 140 deletes the mesh path table (Step SSOS) and returns to
Step SSOl. On the other hand, when the ExpTime 345 of the mesh path table is
undefined (Step S807), the control unit returns to Step S802.
[0310]
When there is no mesh path table in which the expiration time is past the
current time (Step S806), the control unit 140 receives the PREQ and determines
whether or not the identifier of the DestSTA 323 is of its own station (Step S809).
[0311]
When the PREQ is umeceived or the identifier of the DestSTA 323 is not of
30 its own station (Step S809), the control unit 140 receives the PREQ and determines
whether or not the identifier of the DestSTA 323 is of another station (Step S81 0).
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It should be noted that another station refers to one of the information processing
stations other than the information processing device I 00.
[0312)
When the PREQ is unreceived or the identifier of the DestSTA 323 is not of
5 another station (Step S810), the control unit 140 receives a PREP and determines
whether or not the identifier of the OrigSTA 332 is of its own station (Step S811 ).
[0313)
When the PREP is umeceived or the identifier of the DestSTA 323 is not of
its own station (Step S811), the control unit 140 receives the PREP and determines
10 whether or not the identifier of the OrigSTA 332 is of another station (Step S812).
[0314)
When the PREP is unreceived or the identifier of the DestSTA 323 is not of
another station (Step S812), the control unit 140 does whether or not there is an
instruction to finish the communication process (Step S813). Then, when there is
15 an instruction to finish the co111111unication process (Step S813), the operation of the
co111111unication process ends, and when there is no instruction to finish the
co111111unication process, the control unit returns to Step S801.
[0315)
In addition, when the PREQ has been received and the identifier of the
20 DestSTA 323 is of its own station (Step S809), the control unit 140 creates a mesh
path table for the transmission source station of the received PREQ (Step S814).
[0316)
Subsequently, the control unit 140 determines whether or not the identifier
of the TX STA ADDR 303 of the received PREQ is of the transmission source station
25 (Step S815), and when the identifier is of the transmission source station, the control
unit proceeds to Step S817.
[0317)
When the identifier is not of the transmission source station (Step S815), the
control unit 140 creates a mesh path table for the transmitting station of the received
30 PREQ (Step S816). Subsequently, the control unit 140 creates a PREP in response
to the received PREQ, transmits the signal to the tmnsmission source station of the
711113
received PREQ (Step S817), and returns to Step S801.
[0318]
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In addition, when the PREQ has been received and the identifier of the
DestSTA 323 is of another station (Step S810), the control unit 140 updates or
5 creates a mesh path table for the transmission source station of the received PREQ
(Step S818).
[0319]
Subsequently, the control unit 140 determines whether or not the identifier
of the TX STAADDR 303 of the received PREQ is of the transmission source station
10 (Step S819), and when the identifier is of the transmission source station, the control
unit proceeds to Step S821.
[0320]
When the identifier is not of the transmission source station (Step S819), the
control unit 140 creates a mesh path table for the transmitting station of the received
15 · PREQ (Step S820). Subsequently, the control unit 140 creates a mesh path table for
the transmission source station of the received PREQ (Step S821). Subsequently,
the control unit 140 creates a PREQ for transferring the received PREQ, transmits
the PREQ in broadcast (Step S822), and returns to Step S801.
[0321]
20 In addition, when the PREP has been received and the identifier of the
OrigSTA 332 is of its own station (Step S811), the control unit 140 updates a mesh
path table for the transmission source station of the received PREP (Step S823).
Then, the control unit returns to Step S801.
[0322]
25 In addition, when the PREP has been received and the identifier of the
OrigSTA 332 is of another station (Step S812), the control unit 140 determines
whether or not the result of T3-TSx(HopCount of the PREP+l) is TS or smaller
(Step S824). When the result of T3-TSx(HopCount of the PREP+1) is TS or
smaller (Step S824), the control unit 140 sets T4 = TS (Step S825). On the other
30 hand, when the result ofT3-TSx(HopCount of the PREP+!) exceeds TS (Step S824),
the control unit I 40 sets T4 = T3-TSx(HopCount of the PREP+1) (Step S826).
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[0323]
Then, the control unit 140 creates a PREP for transferring the received
PREP and transmits the PREP (Step S827).
[0324]
5 Then, the control unit 140 extracts a mesh path for which the transmission
source station of the received PREP is set to the Des! 341 fi"om the mesh path table,
and sets the NextHop 342 of the mesh path as the Nextl-!op-2 (Step S828).
[0325]
Then, the control unit 140 updates the mesh path table for the transmission
10 source station of the received PREP (Step S829).
[0326]
Then, the control unit 140 determines whether or not the Nextl-!op-2 is the
transmission source station (OrigSTA) (Step S830), and when the Nextl-!op-2 is the
transmission source station (OrigSTA), the control unit proceeds to Step S832. On
15 the other hand, when the Nextl-!op-2 is not the transmission source station (OrigSTA)
(Step S830), the control unit 140 updates the mesh path table for the Nextl-!op-2
(Step S831 ).
[0327]
Subsequently, the control unit 140 updates the mesh path table for the
20 received PREP (Step S832). Subsequently, the control unit 140 determines whether
or not the identifier of the TX STA ADDR 303 of the PREP is of the transmission
source station (destination station of the PREQ) (Step S833), and when the identifier
is of the transmission source station (destination station of the PREQ), the control
unit returns to Step S801.

CLAIMS
Claim 1
An information processing device comprising:
a communication unit configured to perform exchange of a signal for
5 generation or updating of a multi-hop communication path using wireless
communication with another information processing device; and
10
a control unit configured to perform control to update path infonnation
regarding the communication path set tlu·ough the exchange of the signal before the
path information is destroyed.
Claim2
The information processing device according to claim 1, wherein the control
unit decides an effective time for specifying a time at which the path information is
destroyed and decides an updating time for specifying a time during which the path
15 infonnation is updated to be a time shorter than the effective time based on
·expiration time information included in the signal.
Claim 3
The information processing device according to claim 2, wherein the control
20 unit changes the updating time based on a position of the information processing
device on the communication path.
Claim4
The information processing device according to claim 3, wherein, when the
25 information processing device is an information processing device located at an end
of the communication path, the control unit sets the updating time to be shorter than
an updating time of another information processing device on the communication
path.
30 ClaimS
The information processing device according to claim 4, wherein the control
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unit sets the updating time to be the shortest when the infonnation processing device
is the information processing device located at the end and the information
processing device is a transmission source station which has transmitted the signal
first, and sets the updating time to be the second shmiest when the infmmation
5 processing device is the infonnation processing device located at the end and the
infonnation processing device is a destination station which is a destination of the
signal.
10
15
20
Claim 6
The infmmation processing device according to claim 2, wherein the control
unit changes the effective time based on the number of relay stations that are
information processing devices relaying the signal on the communication path.
Claim 7
The infmmation processing device according to claim 2, wherein, when the
same communication path is consecutively selected as a communication path
updated tluough the exchange of the signal, or when a rate of selection of the same
communication path is higher than a predetermined value, the control unit lengthens
the effective time and the updating time.
Claim 8
The infmmation processing device according to claim 2, wherein the control
unit lengthens the effective time and the updating time when an electric field
intensity of an infonnation processing device that is designated as a next
25 transmission destination on the communication path is higher than a threshold value,
and shortens the effective time and the updating time when the elech·ic field intensity
of the information processing device that is designated as the next transmission
destination is lower than the threshold value.
30 Claim 9
The information processing device according to claim 2, wherein, when the
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information processing device is moving, the control unit shmtens the effective time
and the updating time.
Claim 10
The information processing device according to claim 2, wherein, when an
electric field intensity of an information processing device that is not designated as a
next transmission destination on the communication path is higher .than a threshold
value, the control unit shortens the effective time and the updating time.
10 Claim 11
The information processing device according to claim 1, wherein, when
there is an information processing device with the number of packet losses greater
than a threshold value among information processing devices that are designated as
next transmission destinations on the communication path, the control unit transmits
15 a signal for updating the conununication path to another information processing
device on the communication path which includes the information processing device.
Claim 12
The information processing device according to claim 1, wherein, when
20 there is an information processing device which has established a new link to the
foregoing information processing device, the control unit transmits a signal for
updating the communication path to another information processing device on the
conununication path which includes the information processing device.
25 Claim 13
The information processing device according to claim 12, wherein the
control unit transmits a signal for updating the communication path by setting a
random delay time.
30 Claim 14
The information processing device according to claim 1, wherein, when a
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link with an information processing device that is designated as a next transmission
destination on the communication path is disconnected, the control unit transmits a
signal for updating the communication path to another information processing device
on the communication path which includes the information processing device.
Claim 15
An infonnation processing method comprising:
a communication procedure of performing exchange of a signal for
generation or updating of a multi-hop communication path using wireless
10 commnnication with another information processing device; and
a control procedure of performing control to update path information
regarding the communication path set through the exchange of the signal before the
path information is destroyed.