Description
Title of Invention
COMMUNICATION CONTROL DEVICE, COMMUNICATION CONTROL
5 METHOD, AND COMMUNICATION CONTROL SYSTEM
Technical Field
[OOO l]
The present disclosure relates to a communication control device, a
10 communication control method, and a communication control system.
Background Art
[0002]
Secondary usage of a frequency channel is discussed as a method for
15 alleviating future depletion of frequency resources. The secondary usage of a
frequency channel is that part of or all the frequency channels preferentially allocated
to a system is secondarily used by the other system. Typically, a system which is
preferentially allocated with a frequency channel is called primary system and a
system which secondarily uses the frequency channel is called secondary system.
20 [0003]
A TV white space is an exemplary frequency channel whose secondary
usage is discussed (see Non-Patent Literatures 1 and 2). The TV white space is a
channel which is not used by a TV broadcast system depending on an area among
frequency channels allocated to the TV broadcast system as a primary system. The
25 TV white space is opened to a secondary system so that the frequency resource can
be efficiently utilized. A standard for a physical layer (PHY) and a MAC layer for
enabling the secondary usage of the TV white space can employ IEEE802.22,
IEEE802.11 af and ECMA (European Computer Manufacturer Association)-392
(CogNea, see Non-Patent Literature 3 described later).
30 [0004]
The secondary system is generally required to operate so as not to give an
excessive interference to the primary system during the secondary usage of the
frequency channel. An important technique therefor is transmission power control.
For example, Patent Literature 1 described later proposes therein a method for
calculating a path loss from a base station as a master node of a secondary system to
5 a reception device as a primary system and a discrete frequency width between
frequency channels and determining maximum transmission power of the secondary
system based on the calculation result.
Citation List
10 Non-Patent Literature
[OOOS]
Non-Patent Literature 1: "SECOND REPORT AND ORDER AND
MEMORANDUM OPINION AND ORDER", [online], [searched on August 15,
201 11, Internet
Non-Patent Literature 2: "Standard ECMA-392 MAC and PHY for
Operation in TV White Space", [online], [searched on August 15, 20111,
Internet
20 Patent Literature
[0006]
Patent Literature 1 : JP 2009-100452 A
Summary of Invention
25 Technical Problem
[0007]
Generally, the secondary system includes a master node as a device
voluntarily operating the secondary system and a slave node as a device participating
in the secondary system by connecting with the master node. Naturally, not only a
30 wireless signal transmitted from the master node but also a wireless signal
transmitted from the slave node may give an interference to the primary system.
However, in a case where a position of the slave node is not known at the start of
operating the secondary system or the slave node is moved, and so on, it is difficult
to accurately predict an influence of the wireless signal transmitted from the slave
node. Moreover, if the transmission power is to be individually controlled for each
5 slave node, a mechanism for controlling the transmission power is complexed.
[OOOS]
Therefore, it is preferable to provide a simple mechanism able to prevent the
wireless signal transmitted from the slave node from causing an excessive
interference upon operating the secondary system.
10
Solution to Problem
[0009]
According to an embodiment of the present disclosure, there is provided a
communication control device including an information acquisition unit acquiring
15 first information and second information, the first information concerning a position
a guard area for a first wireless communication system, the second information
concerning a position of a master node of a second wireless communication system
which is secondarily operated using a frequency channel used by the first wireless
communication system, a determination unit determining, using the first information
20 and the second information acquired by the information acquisition unit, whether or
not an interval between a reference point of the first wireless communication system
and the master node meets a condition which depends on a width of the guard area
and a communication distance assumed for the second wireless communication
system, and a control unit causing the second wireless communication system to be
25 operated with a given transmission power if the determination unit determines the
interval meets the condition.
[OO 1 01
According to an embodiment of the present disclosure, there is provided a
communication control method, for a communication control device controlling a
30 second wireless communication system which is secondarily operated using a
frequency channel used by a first wireless communication system, the method
including acquiring first information and second information, the first information
concerning a position of a guard area for the first wireless communication system,
the second information concerning a position of a master node of the second wireless
communication system, determining, using the acquired first information and the
5 second information, whether or not an interval between a reference point of the first
wireless communication system and the master node meets a condition which
depends on a width of the guard area and a communication distance assumed for the
second wireless communication system, and causing the second wireless
communication system to be operated with a given transmission power if the interval
10 is determined to meet the condition.
[OOl 11
According to an embodiment of the present disclosure, there is provided a
communication control system including a master node of a second wireless
communication system which is secondarily operated using a frequency channel used
15 by a first wireless communication system, and a communication control device
which controls operation of the second wireless communication system performed by
the master node. The communication control device include an information
acquisition unit acquiring first information and second information, the first
information concerning a position of a guard area for the first wireless
20 communication system, the second information concerning a position of the master
node, a determination unit determining, using the first information and the second
information acquired by the information acquisition unit, whether or not an interval
between a reference point of the first wireless communication system and the master
node meets a condition which depends on a width of the guard area and a
25 communication distance assumed for the second wireless communication system,
and a control unit causing the master node to operate the second wireless
communication system with a given transmission power if the determination unit
determines the interval meets the condition.
30 Advantageous Effects of Invention
[OO 121
According to the present disclosure, the wireless signal transmitted fiom the
slave node can be prevented from causing an excessive interference upon operating
the secondary system.
5 Brief Description of Drawings
[00 131
[FIG 11 FIG 1 is an explanatory diagram for explaining an interference a primary
system suffers upon secondary usage.
[FIG 21 FIG 2 is an explanatory diagram for explaining an in-band interference and
10 a between-band interference.
[FIG. 31 FIG. 3 is as explanatory diagram for explaining a configuration of a
communication control system according to one embodiment.
[FIG. 41 FIG 4 is a sequence diagram illustrating an exemplary schematic flow of a
communication control processing performed in the communication control system
15 according to one embodiment.
[FIG. 51 FIG 5 is a block diagram illustrating an exemplary configuration of a
secondary system manager according to one embodiment.
[FIG. 61 FIG. 6 is an explanatory diagram for explaining an exemplary parameter
regarding a distance used in one embodiment.
20 [FIG. 7A] FIG. 7A is a flowchart illustrating an illustrative first scenario of a power
allocation processing by the secondary system manager.
[FIG 7B] FIG 7B is a flowchart illustrating an illustrative second scenario of the
power allocation processing by the secondary system manager.
[FIG 7C] FIG. 7C is a flowchart illustrating an illustrative third scenario of the
25 power allocation processing by the secondary system manager.
[FIG. 81 FIG. 8 is a block diagram illustrating an exemplary configuration of a master
node of the secondary system according to one embodiment.
[FIG. 91 FIG. 9 is a flowchart illustrating a first example of the flow of the
communication control processing by the master node.
30 [FIG. 101 FIG 10 is a flowchart illustrating a second example of the flow of the
communication control processing by the master node.
[FIG 111 FIG 11 is an explanatory diagram for explaining an exemplary parameter
regarding a distance used for an interference control between the secondary systems.
[FIG 121 FIG. 12 is a flowchart illustrating an exemplary flow of the power
allocation processing by the secondary system manager for the interference control
5 between the secondary systems.
Description of Embodiments
[00 141
Hereinafter, preferred embodiments of the present invention will be
10 described in detail with reference to the appended drawings. Note that, in this
specification and the drawings, elements that have substantially the same function
and structure are denoted with the same reference signs, and repeated explanation is
omitted.
[00 1 51
15 A description will be given in the following order.
1. Outline of system
1-1. Problem relating to first embodiment
1-2. Outline of communication control system
2. Exemplary configuration of secondary system manager
20 2-1. Explanation of units
2-2. Flow of process
3. Exemplary configuration of master node
3-1. Explanation of units
3-2. Flow of process
25 4. Application to interference control between secondary systems
5. Conclusion
[00 161
4. Outline of system>
First, with reference to FIG. 1 to FIG 4, a description will be given of a
30 problem relating to a first embodiment and an outline of a communication control
system.
[00 171
[I- 1. Problem relating to first embodiment]
FIG 1 is an explanatory diagram for explaining an interference a primary
system suffers upon secondary usage. With reference to FIG. 1, there are illustrated
5 a primary transmission station 10 for providing services of the primary system, and a
primary reception station 20 positioned within a service area for the primary system.
The primary transmission station 10 may be a TV broadcast station, or a wireless
base station or repeater station in a cellular communication system, for example.
The cellular communication system may include the GSM, UMTS, WCDMA,
10 CDMA2000, LTEm, LTE-Advanced, IEEE802.16, WiMAX or WiMAX2, and the
like. When the primary transmission station 10 is a TV broadcast station, the
primary reception station 20 is a receiver having an antenna or tuner for receiving TV
broadcast. When the primary transmission station 10 is a wireless base station in a
cellular communication system, the primary reception station 20 is a wireless
15 terminal operating in accordance with the cellular communication system. In the
example of FIG. 1, a channel F1 is allocated to the primary transmission station 10.
The primary transmission station 10 provides TV broadcast services, wireless
communication services or some other wireless services by transmitting wireless
signals on the channel F1. FIG 1 also shows a boundary 12 of the service area and
20 an outer border 14 of a guard area for the primary system.
[00 1 81
FIG 1 further shows master nodes 200% 200b, and 200c each operating the
secondary system. Each of master nodes uses the channel F1 allocated to the
primary system or near channel (e.g., channel F2) to operate the secondary system
25 respectively. In the example of FIG. 1, a slave node 202a participates in the
secondary system operated by the master node 200a on the channel F1. Slave nodes
202b and 202c participate in the secondary system operated by the master node 200b
on the channel F1. A slave node 202d participates in the secondary system operated
by the master node 200c a channel F2. Here, the master node of the secondary
30 system may be a wireless access point which is compliant with or partially uses a
wireless communication system such as IEEE802.22, IEEE802.11, or ECMA, or
may be a wireless base station or repeater station which is compliant with the cellular
communication system or partially uses standards thereof. If the secondary system
is operated in accordance with the cellular communication system, the cellular
communication system may be the same as or different from that of the primary
5 system. The slave node of the secondary system is a wireless communication
terminal supporting the wireless communication system the same as the master node.
The master nodes 200% 200b, and 200c may operate the secondary system in
accordance the same wireless communication system, or may operate the secondary
system in accordance with the wireless communication systems different from each
10 other. At least the master node of the secondary system is typically prohibited from
operating within the guard area for the primary system by regulations. The slave
node may be also prohibited from operating within the guard area.
[00 191
Under the circumstances such as of FIG 1, the primary reception station 20
15 may be influenced by an interference due to the wireless signals transmitted from
secondary transmission stations (both master node and slave node). FIG 2 is an
explanatory diagram for explaining an in-band interference and a between-band
interference. In the example of FIG. 2, the channel F1 is a use channel of the
primary system. The channel F2 is a channel adjacent to the channel F1. The
20 channel F3 is a channel adjacent to the channel F2. A guard band is provided
between the channel F1 and the channel F2, and between the channel F2 and the
channel F3. However, even if these channels F2 and F3 are used by the secondary
system, as illustrated in FIG. 2, a considerable interference may occur from a near
channel (such as channels F2, F3 and other channels) due to out-band radiation.
25 [0020]
In the example of FIG 1, the slave node 202a is positioned closer to the
primary reception station 20 than the master node 200a. For this reason, if the slave
node 202a uses a transmission power equivalent to that of the master node 200a, the
wireless signal from the slave node 202a may give an excessive interference to the
30 primary reception station 20. On the other hand, the slave nodes 202b and 202c are
positioned farther from the primary reception station 20 than the master node 200b.
For this reason, even if the slave nodes 202b and 202c use a transmission power
equivalent to that of the master node 200b, the wireless signal from each slave node
202 does not give an excessive interference to the primary reception station 20. The
same goes for the slave node 202d.
5 [0021]
With existing method, each master node of the secondary system controls
the transmission power used by the master node and slave node in the secondary
system in order to restrict the interference given to the primary system. However,
in a case where the position of the slave node is not known at the start of operating
10 the secondary system, or the slave node is moved, and so on, if the transmission
power for the slave node is to be dynamically controlled in response to appearance,
move and disappearance of the slave node, a mechanism for controlling the
transmission power exceedingly becomes complex. Moreover, an overhead of
signaling increases. Therefore, it is preferable to provide a mechanism able to
15 stably prevent the interference to the primary system using a simpler mechanism.
[0022]
[l-2. Outline of communication control system]
FIG 3 an explanatory diagram for explaining a configuration of a
communication control system 1 according to one embodiment of the technology of
20 the present invention. With reference to FIG. 3, the communication control system
1 includes the primary transmission station 10, a data server 30, a secondary system
manager (SSM) 100, and a master node 200. Here, in the example of FIG 3, only
one master node 200 is illustrated, but actually more master nodes may exist. One
or more slave nodes 202 participate in the secondary system operated by the master
25 node 200.
[0023]
The data server 30 is a server device a having a database storing therein data
on secondary usage. The data server 30 accepts an access from the master node 200
to provide data indicating secondarily usable channels and position data of the
30 transmission station 10 of the primary system to the master node 200. Additionally,
the master node 200 registers information on the secondary system in the data server
30 at the start of the secondary usage. Communication between the data server 30
and the master node 200 may be made via an arbitrary network such as the Internet.
Refer to Non-Patent Literature 1 describing the secondary usage of the TV white
space for an exemplary specification of the data server like this.
5 [0024]
The secondary system manager (SSM) 100 is a communication control
device having a role as a manager managing the secondary usage of a frequency
channel. The SSM 100 allocates the transmission power to the respective
secondary systems so that the interference due to operating the secondary system
10 may not give an excessive influence to the primary system. The SSM 100 can
access to the data server 30 via a network such as the Internet, for example, and
acquires data used for transmission power allocation from the data server 30. In
addition, the SSM 100 is communicably connected with also the respective master
nodes 200. Then, the SSM 100, in response to a request from the master node 200
15 or primary system, or periodically, allocates the transmission power to the secondary
system. Note that, without limited to the example of FIG. 3, the SSM 100 may be
mounted on physically the same device as the data server 30 or any master node 200.
[0025]
FIG. 4 is a sequence diagram illustrating an exemplary schematic flow of a
20 communication control processing performed in the communication control system.
[0026]
First, the master node 200 registers information of the secondary system in
the data server 30 at the start of the secondary usage (step SlO). The information
registered here includes, for example, an ID, class and position of a device starting
25 the secondary usage and the like. Moreover, in response to the registration of the
information on the secondary system, the data server 30 notifies the master node 200
of information for configuring the secondary system such as a list of channel
numbers of secondarily usable frequency channels, acceptable maximum
transmission power and spectrum mask.
30 [0027]
Further, the SSM 100 receives information on the primary system from the
data server 30 periodically, for example, and uses the received information to update
information stored in itself (step Sll). Here, the received information may include
one or more of the position data of the primary transmission station 10, height of an
antenna, width of the guard area, list of channel numbers of the frequency channels,
5 acceptable interference amount of the primary system, list of IDS of the registered
master nodes 200, and other parameters. Here, the SSM 100 may indirectly receive
all or a part of the information on the primary system (e.g., list of channel numbers)
from the master node 200.
[0028]
10 Next, a request for power allocation is transmitted from the master node 200
to the SSM 100 (step S12). When a response is returned to the request for power
allocation, mutual authentication and application level information are exchanged
between the SSM 100 and the master node 200 (step S13). Additionally, the
information on the secondary system is transmitted from the master node 200 to the
15 SSM 100 (step S14). The information transmitted here may include an ID, class
position data of the master node 200, channel number of the frequency channel (the
use channel) selected by the master node 200, and a desired communication distance,
for example.
[0029]
20 Next, the SSM 100 performs the power allocation on the basis of the
information acquired from the data server 30 and master node 200 (step S15). The
power allocation processing here by the SSM 100 will be described in detail later.
Next, the SSM 100 notifies the master node 200 of a result of the power allocation
(step S16).
25 [0030]
Next, the master node 200 configures the secondary system on the basis of
the power allocation result notified by the SSM 100, and starts to operate the
secondary system (step S17). Moreover, the master node 200 reports a result of the
secondary system configuration to the SSM 100 (step S18). The SSM 100 updates
30 the information on the secondary system stored in itself in response to the report
from master node 200 (step S 19).
[003 I]
<2. Exemplary configuration of secondary system manager>
FIG 5 is a block diagram illustrating an exemplary configuration of the
secondary system manager (SSM) 100 illustrated in FIG 3. With reference to FIG
5 5, the SSM 100 includes a communication unit 110, a control unit 120, and a storage
unit 180. The control unit 120 includes an information acquisition unit 130, a
determination unit 140, and a secondary control unit 150.
[0032]
[2-1. Explanation of units]
10 (1) Communication unit
The communication unit 110 is a communication interface for
communication of the SSM 100 with the data server 30 and with the master node 200.
Communication between the SSM 100 and the data server 30, and between the SSM
100 and the master node 200 may be achieved by any of a wired communication or
15 wireless communication, or a combination thereof.
[0033]
(2) Information acquisition unit
The information acquisition unit 130 acquires various information items the
SSM 100 uses for allocating the transmission power to the secondary system from
20 the data server 30 and the master node 200 of the secondary system. For example,
the information acquisition unit 130 receives the information on the primary system
from the data server 30. The information on the primary system includes a first
information concerning the guard area for the primary system. In addition, for
example, the information acquisition unit 130 receives the information on the
25 secondary system from the master node 200 of the secondary system. The
information on the secondary system includes a second information concerning the
position of the master node 200. Then, the information acquisition unit 130 outputs
the acquired information to the determination unit 140.
[0034]
30 (3) Determination unit
The determination unit 140 uses the first and second information acquired
by the information acquisition unit 130 to determine whether or not an interval
between a reference point of the primary system and the master node 200 meets a
condition which depends on the width of the guard area for the primary system and
the communication distance assumed for the secondary system. Then, the
5 determination unit 140 outputs a determination result to the secondary control unit
150. The reference point of the primary system may be typically the closest point
to the master node 200 on the outer border 14 of the guard area. Alternatively, the
reference point may be any point defined within the service area or guard area for the
primary system.
10 [0035]
The above condition used by the determination unit 140 may be expressed
using the parameter regarding the distance illustrated in FIG 6. In the example of
FIG. 6, a distance Dl represents the width of the guard area. A distance D2
represents an interval between the above reference point and the master node 200.
15 In this description, such interval D2 is referred to as a marginal distance. FIG 6 also
shows a communication distance Rpm of the primary system (e.g., radius of the
service area) and a communication distance Rsec assumed for the secondary system.
The communication distance Rsec assumed for the secondary system may be, for
example, a communication distance desired for the secondary system notified to the
20 SSM 100 by the master node 200. Alternatively, the communication distance Rsec
assumed for the secondary system may be held in the SSM 100 in advance. The
communication distance Rsec held in the SSM 100 in advance may be, for example,
an acceptable communication distance about the secondary system.
[0036]
25 In the example of FIG. 6, assume that a next conditional expression (I)
holds between the width of the guard area Dl, marginal distance D2, and
communication distance RSec, for example. Here, in various conditional expressions
illustrated in this description, an inequality sign may be used instead of an equality
sign.
30 [0037]
[0038]
In this case, even if the slave node positioned around an edge of the service
area for the secondary system uses the same transmission power as the master node,
5 the wireless signal (SIG in the figure) transmitted from the slave node does not
practically reach the service area for the primary system. Therefore, the slave node
can easily use the same transmission power as the master node, allowing a complex
control of the transmission power to not be needed for the slave node.
[0039]
10 Here, if the primary system does not have the guard area, the width of the
guard area D1=O holds. In this case, the reference point may be any point on the
outer border 12 of the service area for the primary system (typically, the closest point
to master node 200). The first information concerning a position of the guard area
for the primary system may include information indicating that the primary system
15 does not have the guard area.
[0040]
In addition, as a next expression, a weight coefficient may be introduced to
the conditional expression (1).
[004 11
If the right side of the conditional expression (2) becomes larger owing to
the weight coefficient in the conditional expression (2), a risk of the interference is
more reduced. Alternatively, for example, if no primary reception station exists
25 around the edge of the service area for the primary system, the weight coefficient
may be set such that the right side of the conditional expression (2) becomes smaller.
[0043]
To be more general, these conditional expressions may be expressed by a
function as follows.
[0044]
5 [0045]
According to a conditional expression (3), the determination unit 140 uses
the first and second information to determine whether or not the marginal distance D2
exceeds a threshold Thl set depending on the width of the guard area Dl and
communication distance Rs,,. Note that if the primary system has the guard area
10 (that is, D1>0), the determination unit 140 may uses a next conditional expression (4)
or (5) instead of the conditional expressions (1) to (3).
[0046]
D2 2Rs, f Dl and Dl 2Rsec ( 4 )
D2 2Rs, and Dl 2Rs, ( 5 )
[0047]
15 If the conditional expression (4) or (5) is met, the above described
conditional expression (1) is inevitably met. Therefore, in these cases also, even if
the slave node positioned around the edge of the service area for the secondary
system uses the same transmission power as the master node, the wireless signal
transmitted from the slave node does not practically reach the service area for the
20 primary system.
[0048]
(4) Secondary control unit
The secondary control unit 150 controls the operation of the secondary
system performed by the master node 200 through signaling with the master node
25 200. For example, in this embodiment, if the marginal distance D2 about the master
node 200 meets the above described condition, the secondary control unit 150
controls the master node 200 to operate the secondary system with a given
transmission power. A given transmission power may be typically a transmission
power corresponding to the above communication distance Rsec (able to accomplish
the above communication distance Rsec). A given transmission power here may be
5 applied to not only the master node 200 but also the slave node.
[0049]
If the marginal distance D2 about the master node 200 does not meet the
above described condition, the secondary control unit 150 may carry out any of three
measures described below. That is, first, the secondary control unit 150 may
10 instruct the master node 200 to use a transmission power lower than the transmission
power corresponding to the above communication distance Rsec. Second, the
secondary control unit 150 may suggest usage of other frequency channels to the
master node 200. Third, the secondary control unit 150 may refuse to operate the
secondary system. According to the first measure, although the service area for the
15 secondary system becomes smaller, the secondary system can be ensured to be
operated. According to the second measure, while the service area for the
secondary system is maintained, the secondary system can be ensured to be operated.
However, the second measure is effective only when available other frequency
channels exist. According to the third measure, the secondary system can be
20 extremely easily controlled.
[0050]
The secondary control unit 150 uses the storage unit 180 to manage
information such as the position of the master node 200, use channel, transmission
power allocated to the relevant secondary system and communication distance
25 corresponding thereto with respect to each respective secondary system being
operated. The master node 200 of each secondary system, when the configuration
of the secondary system is completed, reports the configuration of the secondary
system to the SSM 100. Then, the secondary control unit 150, when notified by the
master node 200 of that the above given transmission power allocated to the
30 secondary system is excessive for the relevant secondary system, updates the
transmission power and communication distance about the relevant managed
secondary system to a lower (shorter) value. This allows a larger amount of
transmission power to be allocated to other near secondary systems. On the other
hand, if the transmission power used in the configured secondary system is larger
than the transmission power allocated to the relevant secondary system, the
5 secondary control unit 150 takes measures against violation of primary system
protection (e.g., warning or registration of violating device to the data server 30 and
the like).
[005 11
The secondary control unit 150 may notifL the master node 200 of a value
10 of the assumed communication distance RsK and the width of the guard area Dl.
The value of the communication distance Rsm here may be held the SSM 100 in
advance. This allows, in a case, for example, where the master node 200 is
movable, the master node 200 to move such that the marginal distance D2 meets the
above described condition and the master node 200 to ensure to voluntarily operate
15 the secondary system.
[0052]
(5) Storage unit
The storage unit 180 stores a program and data for operation for the SSM
100 using a storage medium such as a hard disk or semiconductor memory.
20 [0053]
Here, theses components of the SSM 100 shown in FIG 5 are merely
examples. That is, the SSM 100 may additionally include components not shown,
and a part of the components may be omitted from the configuration of the SSM 100.
[0054]
25 [2-2. Flow of process]
In this section, a description will be given of an illustrative three scenarios
of the power allocation processing by the SSM 100.
[0055]
(1) First scenario
30 FIG 7A is a flowchart illustrating a first scenario of the power allocation
processing by the SSM 100 according to this embodiment.
100561
In the first scenario, first, the information acquisition unit 130 acquires the
information on the primary system received by the communication unit 110 from the
data server 30 (step S101). The information on the primary system includes the
5 first information concerning the position of the guard area for the primary system.
Next, the information acquisition unit 130 acquires the information on the secondary
system received by the communication unit 110 from the master node 200 of the
secondary system (step S102). The information on the secondary system includes
the second information concerning the position of the master node 200.
10 [0057]
Next, the determination unit 140 uses the acquired first and second
information to determine whether or not the marginal distance D2 meets the above
described predetermined condition (e.g., any of the conditional expressions (I) to
(5)) which depends on the width of the guard area Dl for the primary system and the
15 communication distance Rsec assumed for the secondary system (step S103). A
value of the marginal distance D2 is calculated as an interval between the reference
point of the primary system and the master node 200. The reference point of the
primary system may be decided as, for example, the closest point to the master node
200 on the outer border of the guard area using the first and second information.
20 [0058]
If the marginal distance Dz is determined to meet a predetermined condition
at step S103, the secondary control unit 150 allocates a given transmission power
corresponding to the communication distance RsK to the secondary system (step
S104). Then, the secondary control unit 150 permits the master node 200 to operate
25 the secondary system (step S 105).
[0059]
Next, the secondary control unit 150 acquires the report on the configuration
of the secondary system from the master node 200 having configured the secondary
system (step S106). Then, the secondary control unit 150 verifies there is no
30 violation of primary system protection (step S107). If there is no violation of
primary system protection, the secondary control unit 150 updates the information on
the secondary system which is managed in the storage unit 180 (step S 108). On the
other hand, there is any violation of primary system protection, the secondary control
unit 150 takes measures against the violation (step S 109).
[0060]
5 In addition, in the first scenario, if the marginal distance D2 is determined to
not meet a predetermined condition at step S103, the secondary control unit 150
notifies the master node 200 of the operation of the secondary system being rehsed
(step S110). In this case, the secondary system does not start be operated by the
master node 200.
10 [0061]
(2) Second scenario
FIG. 7B is a flowchart illustrating a second scenario of the power allocation
processing by the SSM 100 according to this embodiment. Processes from step
S 10 1 to step S 109 in the second scenario are similar to those in the first scenario.
15 [0062]
In the second scenario, if the marginal distance D2 is determined to not meet
a predetermined condition at step S103, the secondary control unit 150 suggests
usage of other frequency channels different from the frequency channel allocated to
the primary system to the master node 200 (step S111). If the master node 200
20 accepts the usage of another frequency channel, the secondary system starts to be
operated on the relevant another frequency channel.
[0063]
(3) Third scenario
FIG 7C is a flowchart illustrating a third scenario of the power allocation
25 processing by the SSM 100 according to this embodiment. Processes from step
SlOl to step S109 in the third scenario are similar to those in the first scenario and
second scenario.
[0064]
In the third scenario, if the marginal distance D2 is determined to not meet a
30 predetermined condition at step S103, the secondary control unit 150 calculates a
transmission power allocable to the secondary system (step S 1 12). For example,
the allocable transmission power may be calculated such that a reception power of
the wireless signal from the relevant slave node is equal to or less than the acceptable
interference amount at the reference point of the primary system even in a case
where the slave node is positioned around the edge of the service area for the
5 secondary system. The transmission power which may be calculated here has a
value lower than the transmission power corresponding to the above communication
distance R,,,. Then, the secondary control unit 150 instructs the master node 200 to
use the calculated transmission power (step S113). If the master node 200 accepts
the instruction to use the transmission power, the relevant transmission power is used
10 to start to operate the secondary system.
[0065]
<3. Exemplary configuration of master node>
FIG 8 is a block diagram illustrating an exemplary configuration of the
master node 200 of the secondary system. With reference to FIG. 8, the master
15 node 200 includes a network communication unit 210, wireless communication unit
215, control unit 220, and storage unit 280. The control unit 220 includes a power
control unit 250, information acquisition unit 260, and determination unit 270.
[0066]
[3-1. Explanation of units]
20 (1) Network communication unit
The network communication unit 210 is a communication interface for
communication of the master node 200 with the data server 30 and with the SSM 100.
Communication between the master node 200 and the data server 30, and between
the master node 200 and the SSM 100 may be achieved any of a wired
25 communication or wireless communication, or a combination thereof.
[0067]
(2) Wireless communication unit
The wireless communication unit 215 is a communication interface
performing wireless communication with one or more slave nodes participating in
30 the secondary system operated by the master node 200.' For example, the wireless
communication unit 215 broadcasts a control signal such as a beacon or reference
signal using the transmission power set by the power control unit 250 described later.
The relevant control signal includes control information indicating a set value of the
transmission power. The slave node, in receiving the relevant control signal, may
use the same transmission power as the master node 200 to participate in the
5 secondary system operated by the master node 200.
[0068]
(3) Power control unit
The power control unit 250 controls the transmission power for the
secondary system operated by the master node 200. In this embodiment, the power
10 control unit 250 before starting to operate the secondary system, registers the
information on the secondary system in the data server 30. Then, the power control
unit 250, for example, selects a channel used for the secondary system from the list
of the channel numbers of the secondarily usable frequency channels provided by the
data server 30. Then, the power control unit 250 requests the transmission power
15 allocation from the SSM 100. The power control unit 250 provides to the SSM 100
the information on the secondary system used by the SSM 100 for the transmission
power allocation. The information provided to the SSM 100 includes positional
information on the master node 200 which is measured by a positioning sensor (not
shown) such as a GPS (Global Positioning System) sensor or held in the storage unit
20 280 in advance. Moreover, the information provided to the SSM 100 may include
the communication distance desired for secondary system to be operated. Then, the
power control unit 250, in being notified of the transmission power to be allocated
when the SSM 100 permits the secondary system to be operated, the relevant sets
transmission power to the wireless communication unit 215 and starts to operate the
25 secondary system.
[0069]
If the transmission power allocated by the SSM 100 is excessive, the power
control unit 250 may configure the secondary system with a lower transmission
power instead of the transmission power allocated by the SSM 100. In that case,
30 the power control unit 250, in reporting the configuration of the secondary system,
notifies the SSM 100 of a value of the transmission power actually used.
[0070]
Moreover, the power control unit 250, if instructed by the SSM 100 to use
lower than the transmission power corresponding to the desired communication
distance or suggested changing the use channel, determines whether or not the
5 instruction or suggestion is to be accepted. In the case where the instruction or
suggestion is accepted, if a desired communication service cannot be achieved, the
secondary system may stop from being operated. On the other hand, if the desired
communication service can be achieved even in the case where the instruction or
suggestion is accepted, the power control unit 250 may start to operate the secondary
10 system with the instructed transmission power or on another frequency channel.
[0071]
(4) Information acquisition unit
The information acquisition unit 260 and the determination unit 270 may be
optionally provided in order to determine the condition in the master node 200 about
15 the marginal distance D2. The information acquisition unit 260 acquires the first
information concerning the position of the guard area for the primary system from
the SSM 100. Additionally, the information acquisition unit 260 acquires the
second information concerning the position of the master node 200 measured by the
positioning sensor or held in the storage unit 280 in advance. Then, the information
20 acquisition unit 260 outputs the acquired information to the determination unit 270.
[0072]
(5) Determination unit
The determination unit 270 uses the first information and second
information acquired by the information acquisition unit 260 to determine whether or
25 not the marginal distance D2 about the master node 200 meets a condition which
depends on the width of the guard area Dl and the communication distance Rsec
assumed for the secondary system. Here, the communication distance RSec assumed
for the secondary system may be, for example, a communication distance desired for
secondary system. Alternatively, the communication distance Rsec assumed for the
30 secondary system may be the communication distance about the secondary system
(e.g., acceptable communication distance) which is notified to the master node 200
by the SSM 100. The above condition used by the determination unit 270 may be,
for example, a condition expressed by any of the above described conditional
expressions (I) to (5). That is, the determination unit 270 uses the first information
and second information to determine whether or not the marginal distance D2
5 exceeds the threshold set depending on the width of the guard area Dl and the
communication distance Rsec. Then, the determination unit 270 outputs a
determination result to the power control unit 250.
[0073]
If the marginal distance D2 is determined to meet the above condition by the
10 determination unit 270, the power control unit 250 may use the transmission power
corresponding to the communication distance Rsec to configure the secondary system.
On the other hand, if the marginal distance D2 is determined to not meet the above
condition by the determination unit 270, the power control unit 250, afier the master
node 200 moves or with the communication distance being shortened, controls the
15 determination unit 270 to again determine the condition about the marginal distance
D2. In this way, in the case where determination of the condition about the marginal
distance D2 is made by the master node 200, the determination about the marginal
distance D2 in the SSM 100.
[0074]
20 (6) Storage unit
The storage unit 280 stores a program and data for operation for the master
node 200 using a storage medium such as a hard disk or semiconductor memory.
[0075]
[3-2. Flow of process]
25 In this section, a description will be given of two examples of the flow of
the communication control processing by the above described master node 200. In
a first example, the determination about the marginal distance D2 is made by the
SSM 100. In a second example, the determination about the marginal distance D2 is
made by the master node 200.
30 [0076]
(1) Condition determination by SSM
FIG 9 is a flowchart illustrating the first example of the flow of the
communication control processing by the master node 200. First, the power control
unit 250 requests the transmission power allocation from the SSM 100 (step S201),
and transmits the information on the secondary system to the SSM 100 (step S202).
5 The information transmitted here may include information such as the positional
information on the master node 200, communication distance desired for the
secondary system, and use channel.
[0077]
Next, when a response from the SSM 100 is received, the power control unit
10 250 determines whether or not the secondary system is permitted to be operated (step
S203). If the secondary system is permitted to be operated, the power control unit
250 further determines whether or not the allocated transmission power is proper
(step S204). For example, if an excessive transmission power is allocated, the
power control unit 250 may set a unique transmission power to accomplish the
15 desired communication distance to the wireless communication unit 2 15 (step S205).
On the other hand, if the allocated transmission power is proper, the power control
unit 250 sets the relevant allocated transmission power to the wireless
communication unit 2 15 (step S206).
[0078]
20 If the secondary system is not permitted to be operated at step S203, the
power control unit 250 determines whether or not to operate the secondary system
with a lower transmission power or on another frequency channel (step S207). In
the case where the secondary system is operated with a lower transmission power or
on another frequency channel, the power control unit 250 sets a lower transmission
25 power or a new frequency channel to the wireless communication unit 215 (step
S208).
[0079]
If the transmission power and the frequency channel are set at step S205,
step S206, or step S208, the master node 200 starts to operate the secondary system
30 (step S209). Then, the power control unit 250 reports the configuration of the
secondary system to the SSM 100 (step S210).
[OOSO]
(2) Condition determination by master node
FIG 10 is a flowchart illustrating the second example of the flow of the
communication control processing by the master node 200. First, the information
5 acquisition unit 260 acquires the first information concerning the position of the
guard area for the primary system from the SSM 100 (step S221). Additionally, the
information acquisition unit 260 acquires the second information concerning the
position of the master node 200 (step S222)
[OOS 11
10 Next, the determination unit 270 uses the acquired first information and
second information to determines whether or not the marginal distance D2 about
the master node 200 meets a condition which depends on the width of the guard area
Dl and the communication distance Rs,c assumed for the secondary system (step
S223). Here, if the marginal distance D2 meets the above condition, the power
15 control unit 250 sets the transmission power corresponding to the communication
distance Rsec to the wireless communication unit 2 15 (step S224). Then, the master
node 200 starts to operate the secondary system (step S225). On the other hand, if
the marginal distance D2 does not meet the above condition at step S223, the
communication distance R,,, may be changed to shorter value and the position of the
20 master node 200 is updated depending on move of the master node 200 (step S226).
After that, the determination unit 270 may again make the determination of step
S223.
[0082]
<4. Application to interference control between secondary system*
2 5 In the above described embodiment, through the condition determination
about the marginal distance D2 which corresponds to an interval between the
reference point of the primary system and the master node 200, the transmission
power able to be mutually used by the master node and slave node is easily allocated
to the secondary system. This can prevent the wireless signal transmitted from the
30 slave node from giving an excessive interference to the primary reception station.
The mechanism like this, as is described in this section, can be also applicable in
order to prevent an interference between the secondary systems.
[0083 j
FIG 11 is an explanatory diagram for explaining an exemplary parameter
regarding a distance used for an interference control between the secondary systems.
5 FIG. 11 shows a communication distance RsecAa ssumed for the secondary system as
a transmission power allocation target and a communication distance Rsec~o f a
secondary system near the relevant secondary system (hereinafter, referred to as near
system). A distance D3 represents a width of the guard area temporarily set for the
near system. The width of the guard area D3 for the near system may be defined as
10 a fixed value in advance. Alternatively, the width of the guard area D3 for the near
system may be variably decided by multiplying the communication distance Rsec~ of
the relevant near system by a constant rate, for example. The distance D2 is a
marginal distance which corresponds to an interval between the reference point on
the outer border of the guard area temporarily set (on the outer border of the service
15 area if D3=0) and the master node 200.
[0084j
In the example of FIG 11, if a next conditional expression (6) holds between
the marginal distance D2, width of the guard area D3, and communication distance
R,,,, even if the slave node uses the same transmission power as the master node, the
20 wireless signal transmitted from the relevant slave node does not practically reach of
the service area for the near system.
[0085]
[0086]
25 Therefore, the slave node can easily use the same transmission power as the
master node, allowing a complex control of the transmission power to not be needed
for the slave node. In addition, as a next expression, a weight coefficient may be
introduced to the conditional expression (6).
[0087]
[OOSS]
To be more general, these conditional expressions may be expressed by a
function as follows.
5 [0089]
[0090]
According to a conditional expression (S), the determination unit 140 in the
SSM 100 determines whether or not the marginal distance D2 exceeds a threshold
10 Th3 set depending on the width of the guard area D3 temporarily set for the near
system and the communication distance Rsec. Then, if the marginal distance D2
exceeds the threshold Th3, the secondary control unit 150 controls the master node
200 to operate the secondary system with a given transmission power. A given
transmission power may be typically a transmission power corresponding to the
15 above communication distance Rsec. Here, a given transmission power may be
applied to not only the master node 200 but also the slave node. Note that the
determination unit 140 may use a next conditional expression (9) or (10) when Dp0,
instead of the conditional expressions (6) to (8).
[009 11
0 2 'Rsec +D3 and D3 2Rs, (9)
20
[0092]
FIG 12 is a flowchart illustrating an exemplary flow of the power allocation
processing by the SSM 100 for the interference control between the secondary
systems.
[0093]
With reference to FIG 12, first, the information acquisition unit 130
acquires the information on the secondary system from the master node 200 as a
transmission power allocation target (step S301). The information acquired here
5 includes the second information concerning the position of the master node 200.
Next, the information acquisition unit 130 acquires information on the near system
which is managed in the storage unit 180 (step S302). The information acquired
here includes the first information concerning the position of the service area which
is used to set the guard area to the near system (e.g., information indicating position
10 of the master node of the near system and communication distance). Then, the
determination unit 140 temporarily sets the guard area to the near system (step S303).
[0094]
Next, the determination unit 140 determines whether or not the marginal
distance D2 about the master node 200 the above described predetermined condition
15 (e.g., any of the conditional expressions (6) to (10)) which depends on the width of
the guard area D3 for the near system and the communication distance Rs,, assumed
for the secondary system (step S304).
[0095]
If the marginal distance D2 is determined to meet a predetermined condition
20 at step S304, the secondary control unit 150 allocates a given transmission power
corresponding to the communication distance Rs, to the secondary system (step
S305). Then the secondary control unit 150 permits the master node 200 to operate
the secondary system (step S306).
[0096]
2 5 On the other hand, if the marginal distance D2 is determined to not meet a
predetermined condition at step S304, the secondary control unit 150 calculates a
transmission power allocable (step S306). For example, the transmission power
allocable may be calculate such that a reception power of the wireless signal from the
relevant slave node is equal to or less than the acceptable interference amount at the
30 reference point of the near system even in a case where the slave node is positioned
around the edge of the service area for the secondary system. The transmission
power which may be calculated here has a value lower than the transmission power
corresponding to the above communication distance Rsec. Then, the secondary
control unit 150 instructs the master node 200 to use the calculated transmission
power (step S307). Here, instead of step S306 and S307, other frequency channels
5 different from the frequency channel allocated to the near system may be suggested,
or the secondary system may be rehsed to be operated.
[0097]
After that, the secondary control unit 150 acquires a report on the
configuration of the secondary system from the master node 200 having configured
10 the secondary system (step S308). Then, the secondary control unit 150 updates the
information on the secondary system which is managed in the storage unit 180 (step
S309).
[0098]
<5. Conclusion>
15 One embodiment and applicable example thereof of the technology of the
present invention are described in detail so far with using FIG 1 to FIG 12.
According to this embodiment, determined is whether or not the marginal distance
which corresponds to an interval between the reference point of the primary system
or near system and the master node of the secondary system meets a condition which
20 depends on the width of the guard area and the communication distance assumed for
the relevant secondary system, and if the relevant condition is met, the secondary
system is operated with a given transmission power. This prevents the wireless
signal transmitted from the relevant slave node from causing an excessive
interference even if the slave node of the secondary system uses the transmission
25 power equivalent to that of the master node. Therefore, the slave node can be
allowed to easily use a transmission power equivalent to the transmission power
allocated to the master node. This means that eliminated is the necessity to provide
a complex transmission power calculation mechanism for each of the master node
and the slave node. Therefore, introduction of the secondary system is facilitated.
30 In addition, even if the position of the slave node is not known at the start of
operation of the secondary system, the wireless signal transmitted from the slave
node can be prevented from causing an excessive interference.
[0099]
The above assumed communication distance may be the desired distance
notified to the secondary system manager by the master node. In that case, if the
5 above condition is met, the transmission power corresponding to a communication
distance desired for the master node can be easily allocated to the secondary system.
In addition, the above assumed communication distance may be a communication
distance stored in the secondary system manager using the storage medium in
advance. In that case, if the above condition is met, the transmission power
10 corresponding to the relevant communication distance can be easily allocated to the
secondary system.
[O 1 001
If the above condition is determined to not be met, the master node may be
instructed to use a transmission power lower than the transmission power
15 corresponding to the above assumed communication distance. Therefore, only in
the case where the above condition is not met, the secondary system manager can
perform detail calculation of transmission power with taking into consideration the
position of the master node, path loss and the like. That is, a calculation load on the
secondary system manager may be suppressed.
20 [OlOl]
Moreover, the determination of the above marginal distance may be made
by the master node of the secondary system instead of the secondary system manager.
In that case, the master node (or a provider who locates the master node) can
voluntarily adjust the configuration of the secondary system. Further, a load on the
25 secondary system manager can be suppressed, allowing an overhead of signaling
between the manager and the master node to be reduced.
[O 1 021
A sequence of control processing by each apparatus described herein may be
realized by using software, hardware, or a combination of software and hardware.
30 Programs constituting software are stored in, for example, a storage medium
provided inside or outside each apparatus in advance. Then, for example, each
program is read into RAM (Random Access Memory) during execution and executed
by a processor such as CPU (Central Processing Unit).
[0 1031
The preferred embodiments of the present invention have been described
5 above with reference to the accompanying drawings, whilst the present invention is
not limited to the above examples, of course. A person skilled in the art may find
various alternations and modifications within the scope of the appended claims, and
it should be understood that they will naturally come under the technical scope of the
present invention.
10 [0104]
Additionally, the present disclosure may also be configured as below.
(1)
A communication control device including:
an information acquisition unit acquiring first information and second
15 information, the first information concerning a position a guard area for a first
wireless communication system, the second information concerning a position of a
master node of a second wireless communication system which is secondarily
operated using a frequency channel used by the first wireless communication system;
a determination unit determining, using the first information and the second
20 information acquired by the information acquisition unit, whether or not an interval
between a reference point of the first wireless communication system and the master
node meets a condition which depends on a width of the guard area and a
communication distance assumed for the second wireless communication system;
and
2 5 a control unit causing the second wireless communication system to be
operated with a given transmission power if the determination unit determines the
interval meets the condition.
(2)
The communication control device according to (I),
3 0 wherein the communication control device is a manager managing
secondary usage of the frequency channel, and
wherein the communication distance is a desired distance notified to the
manager by the master node.
(3)
The communication control device according to (I),
5 wherein the communication control device is a manager managing a
secondary usage of the frequency channel, and
wherein the communication distance is a communication distance about a
secondary system which is held in the communication control device in advance.
(4)
10 The communication control device according to (2) or (3),
wherein if the determination unit determines the condition is not met, the
control unit instructs the master node to use a transmission power lower than a
transmission power corresponding to the communication distance.
(5)
15 The communication control device according to (2) or (3),
wherein if the determination unit determines the condition is not met, the
control unit suggests usage of another frequency channel to the master node.
(6)
The communication control device according to (2) or (3),
20 wherein if the determination unit determines the condition is not met, the
control unit does not permit the second wireless communication system to be
operated.
(7)
The communication control device according to (I),
25 wherein the communication control device is the master node, and
wherein the communication distance is a communication distance about a
secondary system notified to the master node by a manager managing the secondary
usage of a frequency channel.
(8)
3 0 The communication control device according to any one of (1) to (6),
wherein the communication control device is a manager managing a
secondary usage of the frequency channel, and
wherein after the determination unit determines the condition is met, the
control unit, when notified by the master node of that the given transmission power is
excessive for the second wireless communication system, updates the given
5 transmission power to a lower value.
(9)
The communication control device according to any one of (1) to (S),
wherein the first wireless communication system is a primary system, and
wherein the second wireless communication system is a secondary system.
10 (10)
The communication control device according to any one of (1) to (S),
wherein each of the first wireless communication system and the second
wireless communication system is a secondary system secondarily operated using a
frequency channel allocated to a primary system.
15 (11)
The communication control device according to (lo),
wherein the width of the guard area for the first wireless communication
system is a fixed value or a variable value decided depending on of a communication
distance the first wireless communication system.
20 (12)
The communication control device according to any one of (1) to (1 l),
wherein the reference point exists on an outer border of the guard area, or on
an outer border of a service area for the first wireless communication system if the
first wireless communication system does not have the guard area.
25 (13)
The communication control device according to (12),
wherein the condition is a condition based on comparison between the
interval and a difference obtained by subtracting the width of the guard area from
twice the communication distance assumed for the second wireless communication
30 system.
(14)
A communication control method, for a communication control device
controlling a second wireless communication system which is secondarily operated
using a frequency channel used by a first wireless communication system, the
method comprising:
5 acquiring first information and second information, the first information
concerning a position of a guard area for the first wireless communication system,
the second information concerning a position of a master node of the second wireless
communication system;
determining, using the acquired first information and the second information,
10 whether or not an interval between a reference point of the first wireless
communication system and the master node meets a condition which depends on a
width of the guard area and a communication distance assumed for the second
wireless communication system; and
causing the second wireless communication system to be operated with a
15 given transmission power if the interval is determined to meet the condition.
(1 5)
A communication control system comprising:
a master node of a second wireless communication system which is
secondarily operated using a frequency channel used by a first wireless
20 communication system; and
a communication control device which controls operation of the second
wireless communication system performed by the master node,
wherein the communication control device includes
an information acquisition unit acquiring first information and
25 second information, the first information concerning a position of a guard area for
the first wireless communication system, the second information concerning a
position of the master node,
a determination unit determining, using the first information and
the second information acquired by the information acquisition unit, whether or not
30 an interval between a reference point of the first wireless communication system and
the master node meets a condition which depends on a width of the guard area and a
communication distance assumed for the second wireless communication system,
and
a control unit causing the master node to operate the second
wireless communication system with a given transmission power if the determination
5 unit determines the interval meets the condition.
Reference Signs List
communication control system
data server
communication control device (secondary system manager)
information acquisition unit
determination unit
control unit
communication control device (master node)
control unit
information acquisition unit
determination unit
slave node