Title of Invention
COMMUNICATION CONTROL DEVICE, COMMUNICATION CONTROL
5 METHOD, AND COMMUNICATION CONTROL SYSTEM
Technical Field
[OOOI]
The present disclosure relates to a communication control device, a
10 cotn~n~~~iicactoinotrno l method, and a cotntnunication control system.
Background Art
[0002]
Secondary usage of a freqc~ency is discussed as a tneasure for alleviating
15 future depletion of frequetlcy resources. The secondary usage of a frequency mans
that part of or all the fitquency channels preferentially allocated for a syste~n is
secondarily used by the other system. Typically, a systetn which is preferentially
allocated with a frequency cha~lnel is called a prima131 systenl and a system which
secondarily uses the frequency channel is called a secondary system.
20 [0003]
A TV white space is an exetnplary frequency channel wl~ose secondary
usage is discussed (see Non-Patent Literatures 1). The TV ~vhites pace is a channel
which is not used by a TV broadcast system depending on an area among frequency
channels allocated for the TV broadcast system as a pritnary system. The TV white
25 space is opened to a secondary syste~ns o that efficient utilization of the frequency
resource is to be achieved. A standard for a physical layer (PHY) and a MAC layer
for enabling the secondary usage of the TV white space can include IEEE802.22,
IEEE802.llaf and ECMA (European Computer Manufacturer Association)-392
(CogNea, see Non-Patent Literature 2 described later).
30 [0004]
Tlie secondary system is generally required to operate so as not to give a
fatal interference to the pri~nary system upon secondary usagc of a frequency band.
An important technique therefor is transtilissio~lp ower control. For example, Patent
Literature 1 described later proposes therein a method in which a base station of a
secondary system calculates a path loss thereftom to a reception device of a primary
5 systeln and a discrete freqnency width between fteqoe~~cchya nnels, and determines
maximum trarislnission power for the secondaty systetn based on the calculation
result.
Citation List
10 Non-Patent Literature
[0005]
Non-Patent Literature 1: "SECOND REPORT AND ORDER AND
iW3MORANDUM OPINION AND ORDER," [online], [searched on Septenlber 6,
20 1 11, Intemet~URL:littp:lhraunfoss.fcc.gov/edocs~11blic/attaclit~~atcl~/FCC-O8-
15 260Al .pdf>
Non-Patent Literature 2: "Standard ECMA-392 MAC and PHY for
Operation in TV White Space," [online], [searched on September 6, 20101,
l~~ternet~URL:l~ttp://ww~v~~.ecma-intemational.org/p/pnblicatio~~s/standards/Ec~~~a-
392.httn>
20 Patent Literature
[0006]
Patent Literature 1: JP 2009-100452A
Sutntllary of Invetltioll
25 Technical Problem
[0007]
Under the circctmstances ia which a plurality of secotidary systetns exist,
transmission power for each secondary systeln is preferably to be controlled such
that accnm~~lativilelt erfereilces froin the plurality of secondary systems fall within a
30 range acceptable to the primary system. On this occasion, if the tralis~nissionp ower
is sitnply distributed to the plurality of secondary systetns depetiditlg on the path loss
of each secondary system, evely time the nu~nbero f the secondary spstetns increases
or decreases, or the secondary system moves, a transmission power value is to be
updated for the plurality of secondary syste~ns. However, such a fiequent update of
the transmission power value may lead to decrease in system throughput due to
5 increase in signaling.
[OOOS]
Therefore, it is beneficial if a mechanism is achieved which can properly
control accumulative interferences from a plurality of seconda~y systems without
excessively increasing the signaling.
10
Solution to Problem
[0009]
According to the present disclosure, there is provided a co~nmunication
control device including a power distribution tinit configured to distribute, to one or
15 more secondary systems, a transmission power accepted for a secondary usage of a
frequency channel which is protected for a primary system, and a notification unit
configured to notify each secondary system of a value of a second transmission
power which is decided depending on a value of a first translnission power
distributed by the power distribution unit. Upon updating the transmission power,
20 only in a case where a value of the second transmission power which is previously
notified and a value of the first transmission power which is newly distributed by the
power distribution unit satisfy a predetermined condition with respect to a certain
secondary system, the notification unit notifies the secondary systein of a new value
of the second transmission power.
25 [OOlO]
According to the present disclosure, there is provided a co~nmunication
control inethod inclt~ding distributing, to one or more secondaly systems, a
transmission power accepted for a secondary usage of a frequency channel which is
protected for a primary system, and notifying each seconda~ys ystem of a value of a
30 second transtnission power which is decided depending on a value of a first
transmission power distributed by the power distribution unit. Upon updating the
transti~lssion power, only in a case where a value of the scco~~trdat lstnission power
which is previously notified and a value of the first transmission power which is
riewly distributed satisfy a predetemiined cotidition with respect to a certain
secolldaty system, the secondary system is notified of a new value of the second
5 transmission power.
[OO Ill
According to the present disclosure, there is provided a colntnunicatiotl
control systetn including a co~n~nunicatiocno ntrol device itlcludit~g a power
distribution unit configured to distribute, to one or tnore secondary systems, a
10 trans~iiission power accepted for a secondary usage of a freqaency channel which is
protected for a primary system, and a notification unit configured to notify each
secondary systetn of a value of a second transmission power which is decided
depending on a value of a first tra~lsti~issionp ower distributed by the power
distribution unit, and a communication device setting a transmission power for
15 operating the secondaty systetn within a range of the value of the secotid
transtnissiot~ power notified from the communication control device. Upon
updating the transmission powvet; only in a case where a value of the second
transmission po\irer which is previously notified to the comtnanication device and a
value of the first tra~~smissionp ower which is llewly distributed to the
20 coln~ilunicationd evice satisfy a predetermined condition, the notification unit of the
co~n~nunicatiocnon trol device notifies the co~nmunicationd evice of the new value of
the second transmission power.
Advantageous Effects of I~ivention
25 [0012]
According to a technology of the presetit disclosure, the accutuulative
interferences from a plurality of seco~tdary systems can be properly controlled
without excessively increasing the signaling.
30
[00 131
Brief Description of Drawings
[FIG. 11 FIG. 1 is an explanatory diagram for explaining an intcrference a node of a
primary system suffers upon secondary usage of a frequency.
[FIG. 21 FIG. 2 is an explanatoiy diagram for explaining an interference in a channel
and an interference bet\veen channels.
5 [FIG. 31 FIG. 3 is an explanatory diagram for explaining a configuration of a
comtnunication control systenl according to one embodiment.
[FIG. 41 FIG. 4 is a sequence diagram illustrating an exelnplary schematic flow of an
interference control processing perforn~ed in the co~n~nunicatiocno ntrol system
according to one embodiment.
10 [FIG. 51 FIG. 5 is a block diagram illustrating an exe~nplaryc onfiguration of the
communication control device according to one embodiment.
[FIG. 6A] FIG. 6A is a flowchart illustrating a first example of flow of a power
distribution processing according to one etnbodiment.
[FIG. 6B] FIG. 6B is a flowchart illustrating a second example of flo\xr of the power
15 distribution processing according to one embodiment.
[FIG. 6C] FIG. 6C is a floxx~chatt illustrating a third example of flow of the power
distribution processing according to one embodinlent.
[FIG. 71 FIG. 7 is an explanatory diagram illustrating an exe~nplaryc onfiguration of a
secondary system management table according to one embodi~nent.
20 [FIG. 81 FIG. 8 is a flowchart illustrating an example of flow of a power adjust~nent
processing by the communication control device according to one embodiment.
[FIG. 9A] FIG. 9A is a flowchart illustrating a first example of detailed flow of a
power notification deternlnination processing illustrated in FIG. 8.
[FIG. 9B] FIG. 9B is a flowchart illostrating a second example of detailed flow of the
25 power notification determination processing illustrated in FIG. 8.
[FIG. 101 FIG. 10 is a floivchart illustrating an exanlple of detailed flon. of a message
generation processing illustrated in FIG. 8.
[FIG. 111 FIG. 11 is a flowchart illustrating an exanlple of flow of an additional
detennination processing.
30 [FIG. 12A] FIG 12A is an explanato~yd iagram for explaining a first example of a
definition for a distance between the pri~narys ystem and each secondaly system.
[FIG. 12B] FIG. 12B is an explanatory diagram for explaining a second cxa~npleo f
the definition for the distance between the primary system and each seco~ldary
systeal.
[FIG. 12C] FIG. 12C is an explanatory diagratn for explaining a third example of the
5 definitioti for the distance between the primary system and each secondary system.
[FIG. 12D] FIG. 12D is an explanatory diagram for explaining a fourth example of
the defi~litiotl for the distance between the primary systetn and each secondaly
system.
[FIG. 131 FIG. 13 is a block diagratn illustrating of an exemplary configuration of a
10 nlaster node of the secondary system according to one ernbodiment.
Description ofEmbodiments
[0014]
Hereinafter, preferred embodiments of the present invention will be
15 described in detail with reference to the appended drawings. Note that, in this
specification and the drawings, elenlents that have substantially the same f~~nction
and structure are denoted with the same reference signs, and repeated explanation is
omitted.
[00 151
20 A description will be given iin the following order.
I. Outline of system
1-1. Problein relating to one einbodirnent
1-2. Outline of communication cotltrol systetn
2. Basic ir~tesferencec ontrol nlodel
25 3. Exemplary configuration of secondary systetn manager
3-1. Explanation of units
3-2. Flo~vo f process
3-3. Distance between primaty system and secondary system
3-4. Si~nplificationo f tenn of interference between channels
30 4. Exeinplary cot1figc1ratio.n of master node
5. Explanatory modification
6. Conclosion
[0016]
4. Ootline of system>
First, with reference to FIG. 1 to FIG. 4, a description will be given of a
5 probleln relating to one elnbodiment and an outline of a commc~nication control
system.
[0017]
[I-1. Problenl relating to one etnbodiinent]
FIG. 1 is an explanatory diagram for explaining an interference a node of a
10 primary system suffers upon secondary usage of a fieqoency. With reference to FIG.
1, there are illostrated a primary transmission station 10 for providing services of the
primary system, and a primary reception station 20 located inside a boundary 12 of a
service area for the primary system. The pritnaty transmission station 10 may be a
TV broadcast station, or a wireless base station or repeater station in a cellular
15 cotnnlunication system, for example. The cellular communication system may
include the GSM, UMTS, WCDMA, CDMA2000, LTE, 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
20 transtnissio~ls tation 10 is a wireless base station in a cellular communication system,
the primary reception station 20 is a wireless terminal operating in accordance with
the cellular communication system. In the exatnple of FIG. 1, a channel F1 is
allocated for the primary trans~nissiolls tation 10. The pritnaty transtnission station
10 can provide TV broadcast services, wireless cotnmunication services or some
25 other wireless services by transmitting wireless signals on the channel F1.
[0018]
FIG. 1 fitrther sho\vs tnaster nodes 200~1, 200b, 200c, and 200d each
operating the secondaty system. Each of master nodes uses the channel Fl
allocated for the pritnary system or an adjacent channel F2 or F3 to operate the
30 secondary system respectively. Each tnaster node may be a wireless access point
which is compliant with or pattially uses a wireless comtnunication system snch as
IEEE802.22, IEEE802.11, or ECMA, or map be a wireless basc station or repcater
station which is compliant with the cellular communication system or paltially uses
standards thereof. If the secondary system is operated in accordance with the
cellular com~nonications ystem, the cellular comtnunication system tnay be the same
5 as or different from a system of tlie primary system. One or more slave nodes (not
shown) for the secondary system tilay exist around each master node. Slave nodes
support the same wireless comtnunicatiotl system as the master node which they are
connected to. In the example of FIG. 1, a master node 200a located outside a
boundary 14 a guard area uses the channel F1. Master nodes 200b and 200c located
10 inside the gi~ard area use the cliatinels F2 and F3 adjacent to the channel F1. A
master node 200d located outside the boundary 14 the guard area uses the channel F2.
[OOI 91
Under the circi~mstancess uch as of FIG. 1, the primary reception station 20
tnay be influenced by an interference doe to tlie wireless signals transmitted from
15 secondaty tra~ls~i~isssitoa~tiol ils (both master node and slave node). FIG. 2 is an
explanatory diagram for explaining an interference ia channel (in-band) and an
interference between channels. In the example of FIG. 2, the channel Fl is a
channel used by the prinia~y system. If the master node 200a in FIG. 1 secondarily
uses this channel F1, an interference may occur in the same cliannel. The channel
20 F2 is a channel adjacent to the channel F1. Tlie chaunel F3 is a channel adjacent to
the channel F2. A guard band is provided between the cl~annelF l and the channel
F2, and between the cha~nleFl 2 and the channel F3. When these channels F2 and
F3 are used by other system, the primary system is ideally to suffer no interference.
Holvevel; as illustrated in FIG. 2, actually a considerable interference may occur
25 from an adjacent channel (such as channels F2, F3 and other cl~annels)d ue to outband
radiation.
[0020]
In order that the accumulative interferences from a plurality of secondary
syste~ns give 110 negative infl~ience to the primary system, it is preferable that a
30 transmission power for each secondar)~s ystem is dyna~nicallyc ontrolled depending
on increase and decrease in the nutiiber of the secondary systems or move of the
seconda~y system. For example, if the master node 200b newly appears iil a
situation where the master nodes 200a, 200c, and 200d show11 in FIG. 1 are each
operating the secondary system, the transtnissioti powers allocated for the tnaster
nodes 200a, 200c, and 200d are updated to lower values to allow the master node
5 200b to be newly allocated with a transmission power. However, if the
transmission power value is updated for a plurality of secondary systenls in evely
event such as increase atid decrease in the number of the secondary systeln or move
of the secondary system, a message for notifying the transmission power value is to
be frequently exchanges in the system, leading to increase in signaling. Then,
10 excessive increase in the signaling may lead to decrease in system tliroiighpat.
Therefore, a detailed esplanation \\.ill be given in this description of an embodiment
for properly controlling the accumulative interferences fiom a plurality of seconda~y
systeliis to the primary system without the signaling being excessively increased.
[on211
15 [I-2. Outline of communication control system]
FIG. 3 is an explanatory diagram for explaining a communication control
system 1 according to one embodiment. With reference to FIG. 3, the
co~n~nunicatioctol ntrol systetn 1 includes a pritiiary transmission station 10, data
server 30, cotnln~tnicatioti control device 100, and tilaster nodes 2008 and 200b.
20 I-Iere, in the esample of FIG. 3, olily the master nodes 200a and 200b are illustrated
as a master node operating the secondary systetn, but actually more tnaster nodes
may exist. Uilless otherwise the inaster nodes 200a and 200b (and other tnaster
nodes) need to be distinguished frotn each other in the explanation of this description
below, an alphabetical character suffixed to a symbol is omitted to collectively refer
25 to these as the tnaster node 200.
[0022]
The data server 30 is a server device having a database storing therein data
about the secondary usage. The data server 30 accepts an access frotn the tnaster
node 200 to provide data indicating secotldarily usable channels atid positioti data of
30 the transmission statioti 10 of the primary system to the tnaster node 200.
Additionally, the master node 200 registers infomiation on the seco~idarys ystem in
the data server 30 at the start of the secorrdary usage. Co~n~ntioicatiobnet ween the
data server 30 and the master node 200 may be made via an arbitrary network siich
as the Internet. Refer to Non-Patent Literature 1 describing the secondary usage of
the TV white space as to an exemplary specification of the data server like this.
6 [0023]
The co~ii~nunicatiocno ntrol device 100 has a function as a secondaiy system
manager which adjusts the transmission power used by each tnaster node 200 such
that the accumulative interferences fro111 a plurality of secondary systelrrs give no
negative influence to primary system. The communication cotitrol device 100 can
10 access to the data server 30 via a network such as the Internet, for example, and
acquires data used for adjusting the transmission power froin the data server 30. In
addition, the communication control device 100 is communicably connected with
also eaclr master node 200. Then tlre comtnunication control device 100, in
response to a request from tlre master node 200 or primary system, or periodically,
15 adjusts the transmission power for a plutality of secondary systems. Note that,
without limited to the example of FIG. 3, the communication control device 100 may
be mounted on the physically same device as the data server 30 or any of the master
nodes 200.
[0024]
20 FIG. 4 is a sequence diagram illustrating an exemplary schematic flow of an
interference control processing perfornied in the communication control system 1.
I00251
First, the master node 200, before starting to operate the secondary system,
registers infonnation on the secondary system in the data server 30 (step S10). Tlie
25 information registered here may include, for exalnple, a device ID, class and position
data of the master node 200 and the like. Moreover, in response to registration of
the infonnation 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
nutnbers of secondarily usable frequency channels, acceptable ~naxiinum
30 trans~rrission powel; and spectrutn mask. Here, an access cycle from the master
node 200 to the data server 30 nlay be decided on the basis of provisions of law
regarding frequency usage regulation. For exati~ple, the FCC (Fedetal
Communications Commissiot~)is considering a requirement that if the position of the
master node varies, the position data should be updated at least evely 60 seconds.
In addition, it has been recotntnended that the list of the usable channel numbers
5 should be checked by the master node at least evely 30 seconds. However, increase
in the access to the data server 30 leads to increase in overl~ead. Therefore, the
access cycle to the data server 30 may be set to a longer cycle (e.g., integral tnultiple
of the regulated cycle and so on). Moreover, the access cycle lnay be dynalnically
set depending on the nutnber of active nodes (e.g., if the nutnber of nodes is small, a
10 risk of interference is low so that the cycle may be set longer). The data server 30
tnay instr~~tchte tilaster node 200 about the access cycle upon an initial registration
of the infonnation on the secondary system, for example.
[0026]
Further, tlle col~ltlll~nicatiocot~n trol device 100 receives infonnation on the
15 primary systeln from the data server 30 periodically, for example, and uses the
received information to update information stored in itself (step S11). The
infonnation received here 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
the channel numbers of the frequency channels, acceptable interference alnoutlt of
20 the prilnary system, position data of a refe~ence point for interference calculation
described later, list of IDS of the registered master nodes 200, and other parameters
(e.g., ACLR(adjacent channel leakage ratio), fading margin, shadowit~g margin,
protection ratio, ACS (adjacent chalil~el selectiot~) and the like). Here, the
communication control device 100 may indirectly receive all or a part of the
25 information on the prilnary systetn (e.g., list of the channel numbers and the like)
from the master node 200.
[0027]
Next, the tilaster node 200 configures the secondaty systetn on the basis of
the information notified by the data server 30 (step S12). For esample, the tllaster
30 node 200 selects one or more chat~llels fro111 tlie secondarily usable frequency
cha~itiels as a use channel for tlie secondary system. Then, a request for
interference control is translnitted from the master node 200 to thc co~~~ntunicatio~i
control device 100 or from the communication control device 100 to the master node
200 (step S13).
[0028]
5 When an acknowledge is returned to the request for interference control,
mutoal authentication and application level infonnation exchange are performed
bet\\.een the co~nmunication control device 100 and the master node 200 (step S14).
Additionally, the infonnation on the secondary system is transmitted from the master
node 200 to the colnmunication control device 100 (step S15). The information
10 transmitted here may include a device ID of the master node 200, class, position data,
channel number of the frequency channel (use chamlel) selected by the master node
200, iufonnation on a com~nunicationq ilality reqoirement (incloding a QoS (Quality
of Service) requirelnent), priority information, communication histoly and the like.
[0029]
15 Nest, the co~nlnunication control device 100 performs a power adjusttnent
processing on the basis of the information acqnired from the data server 30 and the
master node 200 (step S16). The power adjust~nent processing here by the
colnlni~nication control device 100 will be described in detail later. Then, the
com~nunication control device 100 transmits a power notification message for
20 notifying a newly allocated transmission power to the master node 200 (step S17).
In addition, the comlnunication control device 100 transmits the power notification
message also to the master node 200 of the existing seconda~y system which is
determined to be notified of the newly allocated transmission power.
[0030]
25 The master node 200, in receiving the power notification message, sets an
oatput level of a transmitting circuit in itself in accordance with a valae of the
notified transmission power (step $18). Furthel; the master node 200 may instruct a
slave node connected with itself about a valae of the transmission power to be used.
The master node 200, in conlpleting the setting of the transmission po\vel; reports the
30 secondary systeln configuration to the communication control device 100 (step S19).
Then, the conununication control device 100 updates the information on secondary
system stored in itself in response to the report from the master node 200 (step S20).
[003 I]
Note that here the explanatioti is give11 of the example in which the data
server 30 provides the list of the channel 11111nbers of the secondarily usable
5 frequency cliannels to the master node 200. Holvever, instead of the data server 30,
the communication cotitrol device 100 tnay provide the list of the channel numbers
of the channels recommended for the secondaty usage to the master node 200. For
example, a channel not used by the existing secondary system, a cha~l~iuesle d by a
stnaller number of the secondary systems using the relevant channel, or a channel
10 with a larger rest of the acceptable interference amount is reconltiiended for the
secondary system. Here, the rest of the acceptable interference amount means an
interference amoutit obtained by subtracting an interference atiioutit owing to the
existing secondary system fi.om the acceptable ititerfere~icea mount.
100321
15 e.Ba sic interference co~ltroml odel>
In the above described sequences, tlie power adjustment processing by the
communication control device 100 at step S16 may be a p~~ocessinogn the basis of,
for example, an interference control tilode1 described below. Note that here a true
value expressioti is used to describe tnatbetnatical formulas of tlie interference
20 control model, but this interference control model is applicable to a decibel value
expression by converting tlie tnathe~iiatical formula.
[0033]
First, given that a reference point for the ititerfererice calculation is i, the
freqaency channel allocated for the primary syste~iils f;, tlie acceptable interference
25 a~iloutiot f the primary systetn is IaCwtable(6i), . Additionally, assuming that a single
secondary syste~ikl which secondarily uses the channel f; is located on a periphery of
the guard area. Accordingly, a relation expression below holds among a inaxitnum
tratismissiot~p ower P,,,(f,, k) of the secondary system, a path loss L(i, f;, k) for a
tninin~um separation distance (width of the guard area), and an acceptable
30 interference amount I,o,t~!c(i, 4).
[0034]
'acceptable (i2 fI. )=Pma(fiyk).L(i,fiy(1k))
[0035]
Here, a position of the reference poilit is decided on the basis of the
infor~nationt he co~~imunicatiocno ntrol device 100 receives frotn the data server 30
5 at step S11 in FIG. 4. In a case where the reference point is defined in advance, the
position data (e.g., longitude and latitude, etc.) representing the position of the
relevant reference point may be received fiorn the data server 30. Additionally, the
communication control device 100 tilay use the position data of the node, service
area, or guard area of tile primary systetn received fro111 the data server 30, and the
10 position data received frotn each master node 200 to dynalnically decide tlie position
of the reference point.
[0036]
If a plurality of secondary syste~ils exist, allocation of the transtnission
power for each secondary system is required to satisfy a relation expression below
15 obtained by extetidiog Formula (1).
[0037]
[0038]
Here, the first term of a right-hand side in Fortnula (2) represents the SLII~oIf
20 interference a~nountsc aused by the secondary systems to which seco~tdarilyu se a
channel the same as the channel ij allocated for the primary system. Mj is tlie
number of the seconda~ys ystetils which secondarily use the same channel, P(fj, k) is
a power allocated for the k-th secondary stem, L(i, ij, k) is a path loss between the
k-th secondary systetn and the reference point i of the primary system, and G(fj, k) is
25 a gain component. Ful.ther, the second tern1 represents tlie sunl of interference
amounts caused by the secondary systeriis \vllich secondarily ilse an adjacent channel
different from the channel 6. 0, is the number of adjacent channels, jj is an index of
the adjacent channel, Nj is the number of the secondaly systems which secondarily
use the adjacent channel, kk is an index of the secondary system which secondarily
5 uses the adjacent channel, and H(6, f,, kk) is a loss colnponent with respect to a
secondary system kk fro111 tlie adjacent channel 4 to the chan~~fe;.l Note that the
above Mj atid Nu may be the number of the active secondary systems (or master
nodes).
[0039]
10 The gain comi~onent G in Forin~rla (2) may be decided on the basis of
mainly factors shown in Table 1 below.
[0040]
Table 1. Factor of gain cot~lponentbetrnemsyste~~ls
Symbol
IJ 0
0
D ( i , f o j
15 For example, the protection ratio PR in Table 1 inay be applied with a
Factor
frequency 4; - fj therebetwee11
Shadowing malgin
Shadowing (standard deviation)
Signal disct.in~ination decree based on antenna - ~
D i f ( O 1
G i f 1
L i , f o j
concept as below. Specifically, given that an acceptable interferelice a~nountf rom
PR (fjj - fj) I Protection ratio between channels with an inteivat of
- -
directionality of the prinmy reception station at the
channelfj(f*) and the reference poititi
Signal discl%~litlatiotdl egree based on polarization of
the pritnaty receptiotl station at the cl~anncl4 (f$ and
the reference point i
Antenna gain of the primaty recytiot~ station at the
channelfj(6) and thereference point i
Fader loss of the primaty nception station at' the
channel fi(f5) and the reference point i
the secondary system which secondarily uses a channel f c t~o tlie primary system
[004 I]
using a channel fns is an Iaccepiable Furtliel; a reception power required for the
primary system is P,,(f~s). A formula as below holds between these paranleters.
20 [0042]
[0043]
Note that when the protection ratio is expressed in decibels, a formula as
below may be used in place of above Fonnula (3).
5 [0044]
'acceptable = e e q (fBS ) O pR(f~~-f~)l10
( 4 )
[0045]
The loss component H it1 Fortnula (2) depends on, for example, adjacent
channel selectivity and a leakage ratio. Here, for details of these gait1 cotnponent
10 and loss component, refer to, for example, "Technical and operational require~nents
for the possible operation of cognitive radio systetns in the "white spaces" of the
fieqnency band 470-790 MHz" (ECC Report 159, 2010).
[0046]
<3. Exemplary configuration of secondary system manager>
15 FIG. 5 is a block diagram illustrati~~agn exe~nplaryc onfiguration of the
co~n~nunicatiocnon trol device 100 (that is, secondary system manager) illustrated in
FIG. 3. With reference to FIG. 5, the communication control device 100 includes a
commu~~icatiounn it 110, storage unit 120, and control unit 130. The control unit
130 inclndes a power distribution unit 140 and notification unit 150.
20 [0047]
[3-1. Explanation of onits]
(1) Communication unit
The com~i~unication unit 110 is a cotumunication interface for
co~nmunicationo f the communication control device 100 with the data server 30 and
26 with the master node 200. Comtnunication between the communication control
device 100 and the data server 30, and between the co~nrnnnication control device
100 and the master node 200 may be achieved by any of a wired communication or
wireless con~municationo, r a coinbination thereof.
100481
(2) Storage unit
The storage unit 120 stores a prograin and data for operation for the
5 connnunicatio~i control device 100 using a storage medium such as a hard disk or
semiconductor memory. For example, tlie storage unit 120 stores the information
011 the primary systeln received froin the data server 30 and the information on the
secondary systeln received from the master node 200 of each secondary system. In
this emboditnent, the storage unit 120 has a secondary systeln management table 122
10 which is referred to or updated by the power distribution unit 140 and notification
unit 150. An exemplary connfigoration of the secondary systetn management table
122 will be specifically described later.
[0049]
(3) Power distribution unit
15 The power distribution unit 140 distributes to one or inore secondary
systenis the transmission power accepted for the secondary usage of the frequency
clianncl \\~liich is protected for the primary system. The fieqaency cIia1111e1
protected for the primary systetn nlay include the frequency channel allocated to the
primary systeln and the adjacent frequency channels thereof. In this description, a
20 first tra~lsnlission power which is calculated for each secondary system as a result of
calculating the power distribution by the power distribution unit 140 is referred to as
an acceptable transmission power. 011 the other hand, the notification unit 150
described later notifies each secondary systetn of a value of the second transnlission
power which is decided depending on a value of the acceptable transmission power
25 distributed by the power distribution unit 140 if a predetermined condition is
satisfied. In this embodiinent, the second transnlission po\Frer notified to each
secondary systenl in this Tvay is referred to as an allocable transmission power.
I-Iereinafie~; three examples of a power distribution processing will be described
which nlay be performed by tlie power distribution tnlit 140.
30 [0050]
(3-1) First example
FIG. 6.4 is a tlo\vchart illustrating a first example of flow of the power
distribution processing by the power distribution unit 140. In the first example, the
power distribution unit 140 temporarily allocates for each frequency channel the
transmissio~l power to the secondary system which seco~ldarily uses the relevant
5 frequency channel, and thereailel; redistributes the temporarily allocated
transmission power with taking into account the influences among different
freq~ency channels. Then, the power distribution unit 140 modifies the
transmission power after allocatio~lo r redistribution so as to meet Formula (2) in the
interference control rnodel described above.
10 [0051]
With reference to FIG. 6A, first the power distribution unit 140 acquires
from the storage unit 120 the ittformation on the primary system provided from the
data server 30 (step S101). In addition, the power distribution unit 140 acquires
from the storage unit 120 the information on the secondary syste~nc ollected fiom the
15 il1astef node 200 (step S102). Nest, the power distribution unit 140 repeats the
process of step S103 for each frequency channel used by the secondary system.
[0052]
At step S103, the power distribution unit 140 temporarily allocates the
transtnission power among the secondary systems using a certain target chamlel (step
20 S103). Temporal allocation of the tra~lsmission power may be carried out in
accorda~~wceit h, for example, any of three kinds of method, a fised margin method,
even i~letlloda nd oileve11 method, described belo\\!.
[0053]
(Fixed margin method)
26 A first method is a fised margin method. I11 a case of the fised margin
method, a distribution margin MI (and safety margin SM) fixedly set in advance is
used to easily calculate the transmission power allocated to each secondary system.
hl this case, a calculation cost for allocating the transmission power decreases. A
transtnissioil power P(fj, k) which is temporarily allocated to the k-th secondaly
30 system to use the frequency chan~le4l is derived from a formula belo\\(.
[0054]
[0055]
(Even method)
A second method is an even tnethod. In a case of the even tnethod, the
6 transmission powvers allocated to respective secondary systems are equal to each
other. In other words, the transmission power is evenly distributed to a plurality of
secondary systems. The transmission power P(6, k) which is temporarily allocated
to the k-th secondary systetil to use the freq~zency channel f, is derived fio~n a
fonnnla below.
10 [0056]
[0057]
(Uneven method)
A third nlethod is an uneven method. In a case of the uneven method, the
15 secondary system has the larger distance to the primary system, the secondary system
is allocated with the more transmission powel: Accordingly, chances of the
secondary usage as a whole may be increased. The transmission power P(f,, k)
temporarily allocated to the k-th seconda~ysy stem to tlse the frequency channel f, is
derived fiom a formula below.
20 [0058]
[0059]
Moreovel; the even method and the tineven method nlay be cotnbined with
an interference-causing margin reduction method described below.
[0060]
(Interference-causing margin reduction method)
The interference-causi~~mga rgin reduction tnethod is a neth hod in which the
safety margin SM for reducing an interference risk is counted, and may be used in
5 cotnbi~iation with the even method or uneven lnethod described above. The
transmission power P(6, k) is derived from For~iiula (8) below in terms of the
combination with the even method, and Fortnula (9) belowv in terlns. of the
colnbination with uneven tnethod. Here, SM represents a safety margin set in
advance or notified from the master node 200.
10 [0061]
[0062]
Further, the methods described above ]nay be combined with a weighted
distribution inethod described below.
15 [0063]
(Weighted distribution method)
~..:, : , . . . The weighted distribution method is a inethod inwhich distrib~~tioonf the .. .
traasmission power is weighted depeliding on a priority for each the secondary
system. The tratlsmission power P(6, k) is derived from Forlnula (10) below in
20 terms of the combination with the even method, and Foriiiula (11) below in tenns of
the conlbination with the uneven method. In addition, the trat~s~nissiopno wer P(f;,
k) is derived from Fortnula (10') below in terms of the co~nbinationw ith the even
tnethod and interference-causing margin reduction method, and Formula (11') below
in terms of the cotnbination with the uneven method and interference-causing ~nargin
25 rednction method. Here, wk represents a weighting depending on the priority.
Note that a weight wvj for each frequency channel may be used in place of the weight
wk for each seconda~ys ystem.
[0064]
At1
P(f,, k) = ( w, 3 *v, ) I,,,,",, ( 3' f ) ~ C { ~ ( i , f , > k k ) ~ ( f , > k k ) ) , ( 1 0 )
kk=l k k l
[0065]
5 Here; in the primary systeln there tnay be some cases where only the
acceptable interference amount IaccepfablefU(i), of the frequency channel f, is defined
and the acceptable interference atnount of the adjacent freqttency channel f, is riot
defined. For example, such a case may occur \\'hen the frequency channel fa is a
chatl~lel allocated to the primary system, and the adjacent channel fi thereof is a
10 channel not used by the primary systetn but protected. In that case, a distribution
: . forlllula for distributing the trallslnission power to the' seconda1-j~ systems which
secondarily use the adjacent channel f, is derived by, in the distribution formulas
described above, replacing the acceptable interference atnount Iacceptublef,()i, w ith the
Inceeptlblc(fUi, ) and replacing the tern1 L(i,f,, k).G(f,, k) of the path loss and gain
15 cotnpollent with a term L(i,f,,k).G(fi, k)/H(fU, 4, k) for col~tltitigth e loss component.
As an example, a distributioil fonnula in the fixed margin method tnay be modified
as below.
[0066]
When the process at step S103 is completed for all the frequency channels
used by the secondary systems, the power distribution unit 140 fi~rther counts an
interference between channels to redistribute the trat~stnissiotl power among the
5 secondary systems (step S104). For example, redistribution of the transmission
power in the even method is carried out in accordance with Formula (12) below
(Fomlula (12') in a case of the combination with the interference-causing margin
reduction method).
[0068]
[0069]
Formula (12) means that an acceptable interference amount remained by
subtracting an interference amount owing to usage of the adjacent channel from the
acceptable interference amount of the primary system is redistributed among the rest
15 of the secolldary systems. Similarly, redistribution of the transmission power in the
uneven method may be carried out in accordance with Formula (13) (Fontlula (13')
in a case of the combillatiotl with the interference-caasing tnargin reduction method).
[0070]
[0071]
Here, a weight in the weighted distribution inethod [nay be naturally f~nther
applied to the mathematical formulas for redistribution described above.
[OO72]
5 Next, the power distribution unit 140 searches the service area of the
primarp system for a point having the severest interference amount which is
evaluated on the basis of the trans~nission power after redistribution (step S105).
For example, a point i' having the severest interference atnount is searched for as
shown in Formula (14) or Forlnula (14') below.
10 [O073]
I 'occpi"are (i f . ) - C P f ( f , , k ) . ~ ( i , f , , k ) . ~ ( f j , k ) . ,
i' = arg min k=l
1
01 hi,
-~~{pl(f,,kk).~(i,f,,kk).G(f,,kk)/~(f,f,,, kk)l
4 )
,=I kk=l
[0074]
Nest, the power distribution unit 140 calculates a correction coefficient A
for the poower distribution as shown in For~nula below on the basis of a total
15 interference amount at the point i' and acceptable interference atnou~ltI acceptable(4i,)
(step S106).
[OO75]
[0076]
Here, above Forlnula (15') may be used in a case where the interferencecausing
margin reduction method is applied upon the power distribution.
5 [0077]
Then, the power distribution unit 140 uses the calculated correction
coeff~cienAt to modif>ft he transmission power in accordance with a formula below
and derive an acceptable transmission power PU(fj,k) of the secondary systenl k (step
S107).
10 [0078]
[0079]
Note that in the case of not taking into account the influences among
different frequency cha~lnelst, he redistribution of the transmission power described
15 above (step S104 in FIG. 6A) may be omitted. In that case, in Formula (13) to
Formula (16), the transtnission powers P(4, k) and P(f,, kk) inay be used in place of
the trailsismission powers P'(fj, k) and PI(!", kk), respectively.
[OOSO]
(3-2) Second esatnple
FIG. 6B is a flowchail illustrating a secorid example of flow of the power
distribution processing by the power distribution unit 140. In the second example,
similar to the first example, the power distribution unit 140 te~nporarilya llocates for
each freqtiency channel the transn~ission power to the secondary system which
5 secondarily uses the relevant frequency channel, and thereafter, redistributes the
temporarily allocated transmission power with taking into account the inflnences
atnotlg different frequency channels. However, in the second example, the power
distribution unit 140 confir~nst he teinporariiy allocated transmission power in a
stepwise manner, for example, depending on the priority for each secondary system
10 or for each frequency channel.
[0081]
I11 the example of FIG. 6B, first, the power distribution unit 140 tetllporarily
distributes the translnission power for eacli channel with respect to all the frequency
cl~annelsu sed by the secondary systems sitnilarlp to the first example (step SlOl to
15 step S103). Nest, tlie power distribution unit 140 determines whether or not the
temporarily distributed transmission power meets Formula (2) in the interference
control model describe above (step S109). I-Iere, if For~nula (2) is not met, the
process proceeds to step S110.
[0082]
20 At step S110, the power distribution tunit 140 confirms the power
distribution to the secondary system having higher priority among the secondary
systetns with tlie po\\.er distribution being uncotlfir~ned (step S110). For example,
the power distribution unit 140 lnay confir111 the translnission power which is
temporarily distributed to the secondary ssytetii having higher priority as the
25 acceptable translilission power for the relevant secondary system without any change.
lastead, the power distribution unit 140 may confinn, for example, a value obtained
by multiplying the temporarily distributed trans~nissiop~ol wer by a weight depending
011 the priority as the acceptable transmission power for the relevant seco~idaty
system.
30 [0083]
Next, the po\\Ier distribution unit 140 couiits the interference between
channels to redistribute ttie transmission power to the rest of the secondary spsteins
with the power distribution being unconfirmed (step S111). A calculating formula
here may be the same as Formula (12) or Formula (13) described above.
[0084]
5 After that, at step S109 in a case ~vhere Fol'mula (2) is met, the power
distribution unit 140 confir~ns the temporarily distributed transmission power or
redistributed transmission power as the acceptable transmission power with respect
to all the secondary systems (step S112).
[0085]
10 (3-3) Third example
In a third exanlple of the power distribution processiilg, the power
distribution unit 140, differently from the first example and second example, decides
allocation of the transmission power without through a step temporarily distributing
the trans~nissionp ower for each frequency channel.
15 [0086]
First, given that difference between a left-hand side and a right-hand side
in Formula (2) is Dj, and then Fornlula (2) can be represented as below.
[0087]
20 [OOSS]
Here, assuming that the acceptable interference amo~ultI acceptablefj()i ,( j=l, ...,
0,) for each frequency channel is given. Moreover, given that the trans~nission
power allocated to each of Mj + Nj secondary systenls is P, (s=l, ..., M, + Nj). Then,
by extending Fonnnla (17), a relation expression below holds between an 0,-
25 dimensional acceptable interference a~nount vector and an M, + Njj-dimensional
transmission power vector.
[0089]
[0090]
A coefficient a,j appearing in Formula (18) which is multiplied by a
translnission power P, of the s-th secondaty systenl in terms of the j-th frequency
5 channel inay be calculated on the basis of the path loss L, gain component G and
loss component H in the interference control n~odeld escribed above. Therefore, the
power distribution unit 140, after calculating a coefficient nlatrix in Formula (18),
may derive a solution For~nula (18) to calculate a transnlission power vector (PI, ...,
p ~ j + ~ j ) .
10 [0091]
Given that the acceptable interferer~ce amount vector is I,,,,,tab~,, the
transmission power vector is P,., and the coefficient matrix is A. Then, Fornlula
(18) is represented as below. Here, elements of a vector D corresponding to the
margin niay be fixed values or zero.
15 LO0921
[0093]
For example, if the nuniber of the secondary systems, Mj + Nj, is equal to
the number of the frequency channels, O,, the power distribution unit 140 can
20 calculate the transmission po\jrer vector (PI,. .., Ph$j+~ujs)i ng an inverse lilatrix of tlie
coeflicient matrix A which is a square matrix ... as below.
[0094]
[0095]
Note that is the number of the secondary systems, Mj 4 N,, is not equal to
the number of the frequency channels, O,, the power distribution unit 140 may decide
5 one transinission power vector selected fro111 a plurality of solutions of the
transmission power vector as a solutio~ol f the transmission power to be allocated to
each secondary system. Additionally, the solution of Forlnala (18) lnay be an
approximate solution. Fui.ther, in place of the number of the secondary systems, Mj
+ N,, the number obtained by accumulating the m~mbero f the secondary systems to
10 be taken into account for each channel may be dealt with as a dimension nu~nbero f
the transmissiotl power vector as sliow~iln a forinula below.
[0096]
[0097]
15 FIG. 6C is a flowchalt illustrating the third esa~npleo f flow of the power
distribution processing by the power distribution unit 140.
[0098]
With reference to FIG. 6C, first, the power distribution unit 140 acquires
from the storage unit 120 the information on the prilnary systeln provided from data
20 server 30 (step SlOl). The inforination acquired here includes the acceptable
interference amount vector Iacceptable in Forlnula (18). In addition, the po\TTer
distribution unit 140 acquires from the storage unit 120 the information on the
secondary system collected from the master node 200 (step S102).
[0099]
26 Nest, the power distribution unit 140 calculates, in accordance with the
interference control nlodel described above, the coefficient ~natrixA of a relation
espressio!~ between a transmission pourer vector PL, and the acceptable interference
amount vector Iaceeptable (step S114). This allows a relation expression to be made
such as Formula (18) between the tra~istnission power vector P& and the acceptable
interference amount vector Taeeepfable. Then, the po\ver distribution unit 140 solves
5 the made relation expression to decide distribution of the transmission power and set
each element of the transmission power vector as the acceptable transtnission power
for each secondaty system (step S115).
[O 1001
Note that three po\ver distribution processing described here are inerely
10 examples. That is, the poower distribution unit 140 may distribute the transmission
power to the secotldary systetn using other methods. Moreover, FIG. 4 shows the
example that the transmission power is adjusted in response to a new secondary
system appearance (that is, increase in the number of tlie secondary systems).
However, more generally, the acceptable transmission po\xrer may be updated in
15 response to various events including change in tlie number of the secotidary systems
or move of the secondary systeeln, or periodically to determine a predetertnined
notification condition by the tlotificatioll unit 150 described below.
[0101]
(4) Notification unit
20 The notification unit 150 decides a value of the allocable transmission
power depending on a value of the acceptable tratistnission power distributed by the
power distribution unit 140. Then, if a predetennined notification coltdition is
satisfied, the notiticatiou unit 150 notifies each secondary system of the decided
value of the allocable transtnissioti power. The value of the allocable transmission
25 power tnay be typically decided by renloving a predetermined ~nargitlfi .0111 the value
of the acceptable transmission powel: For example, given that the value of the
acceptable transmission power distributed to the seconda~ys ystem k in tenils of the
channel f, is Pt,,,,($, k), and then, a value P,(f,,k) of the allocable transtnissiot~ power
tnay be decided using a margin Z as shown in a formula below.
30 [0102]
[0103]
A value of the margin Z may be stored as a fixed value by the
co~lltnunication control device 100 in advance, or may be dytianlically decided
6 depending on a value P,,, of the acceptable transmission power or other parameters,
for example. Moreover, a different value of the tnargin Z may be used for each
channel. -
[0104]
The notification condition for the notification unit 150 to newly notify the
10 secondary system of the value of the allocable transmission power may be
represented using a value of the allocable transmission power which is previously
notified and a value of the acceptable transmission power which is newly distributed
with respect to the relevant secondary system. Given that, with respect to a ce~tain
seconda~y system, a value of the allocable transtiiission power which is previously
15 notified is P,,,,,, a value of the acceptable transnlission power which is newly
distributed is Pt,,,,,,,, and a value of a ne\v allocable transtnission power which is
decided from P,,,,,,,,, in accordance with Fortnula (22) is P,,n,,,.. Then, the
notification condition tnay be represented as sho\vn in a fornlula below.
[O 1051
[0106]
Formula (23) mans that the value PL,,,,~, of the allocable transmission
power which is previously notified is larger than the value Pt,np,noo f the acceptable
transmission po\\.er which is newly distributed. If such an inequality is satisfied,
25 the secondary systenl is using the transnlission .power larger than the acceptable
transmission power calculated in response to the no st recent status. Therefore, the
notification unit 150 notifies the secondary system of the value Pt\,llE,, of the new
allocable transmission power in order to decrease the transmission power used by the
secondary system.
[0 1071
5 Formnula (24) means that a difference obtained by si~btracting the value
P,,,, of the allocable transtnission power which is previously notified from the new
value PL,,,,, of the allocable transmission power decided depending on the value
of the acceptable transmission power which is newly distributed is larger than
a predetennined thresl~old Thh. If such an inequality is satisfied, no excessive
10 interference occurs to the primary system even if the transmission power the
secondary system is currently using is increased up to the allocable transmission
power calculated in response to the n~ostr ecent status. Therefore, the notification
unit 150 notifies the secondary systenl of the value of the new allocable transmission
power Ph,,,c,,. in order to increase the transtnission power for the secondary system to
15 extend a communication chance. The threshold Tht, may be stored as a fixed value
by the comtnunication control device 100 in advance, or may be dynatnically decided
depending on the value Ph,PrcV of the allocable transmission power or other
parameters, for example.
[0 1081
20 Here, the notification unit 150 may, with respect to the newly appearing
secondary system, notify of the value of the new allocable transmission power Phnem
without deter~ninationo f the above notification condition.
[0 1 091
As shown in Fornlola (22), in this embodiment, the margin Z is counted in
25 the value or the allocable transmission power notified to the secondary system. In
other words, the value of the allocable transmission power is a value obtained by
subtracting a predetennined margin from the value of the acceptable transmission
power. Therefore, even in a case where the acceptable transmission power lnay
decrease in response to changing statuses such as increase and decrease in the
30 namber of the seconda~y system or move of the seconda~y system, a respite is left
until the acceptable transmission power falls below the transtnission power the
secondary syste~u is using. Then, so long as the acceptable transmission powei.
does not fall below the transmission power the secondary systetn is using, tlie
allocable transtnission power for the relevant secondary system is no updated.
Moreover, even if the acceptable transmission power tilay increase, the allocable
5 transmission power for the secotidary systetn is not updated until an increasing width
thereof exceeds a certain level (level corresponding to tlie above threshold ThL,).
Therefore, the excessive interference to the pritnaty system is avoided as well as
increase in the signaling for notifying the allocable tratlstnission power is suppressed.
[OllO]
10 Typically, the value of the allocable transmission power nlay be discretely
updated in ter~nso f integral ~nultipleo f a predetertnitled unit of update (e.g., 1 dBtn
or 5 dBm). The notification unit 150 tnay notify each secotidary system of the nem
value of the allocable transtnission power by, for example, signaling a difference
value of the allocable tratls~nissioll power to each secondary system. A difference
15 value dPk of the allocable transmission power Inay be calculated by a forrnula below.
[Olll]
[O112]
The notification unit 150 may signal the difference value quantized by ufse
20 of the above predeternlined unit of update in order to further reduce the overhead of
signaling. Given that the unit of update is p,,,,,, atid then dPk may be quantizes as
sholvn in a fonnula below.
[O113]
25 [0114]
Therefore, the power notificatioti message trans~nitted froni the notification
rltiit 150 to each secondary systeln nlay include a master node 200 address of each
secondary systetn as well as a difference value dP,,,,,,l,zd of the quantized allocable
transmission power above. This allows a bit length of the tnessage to be reduced
compared with a case where the new value of the allocable transmission power P,,,,,,
5 itself is included in the power notification message.
[0115]
The notification unit 150, it1 addition to the deter~~ninatioonf the above
notification condition, deterlllines whether or not the accumulative interference
amount to the primary system violates the acceptable interference amount, and may
10 not uotify the secondary systeul of the new value of the allocable trans~xlissiopt~o wer
if the accumulative interference amount does not violate the acceptable interference
amount.
[0116]
The acculnulative interference anlolint to the prilliary systetn ma)r be
15 estimated as a sum 4) of the interference amounts to the primary system on the
basis of the values of the allocable transtnissio~~po wers across one or more
seco~ldary syste~~a~s ss hown it? a fortnula below. Note that, used as the
transmission power value Ph are the new value P,,,,,. of the allocable translnission
power for the tlew secotldary system and the value PI,,,,, of the allocable
20 transmission power which is previously notified for the existing secondary system in
a for~llulab elow.
[0117]
PLYP,,,,,k()f j (new s~tstertt)
wherein c T ( f j , k=)
, ,f ,k ) (existing sysfenz)
[OI 181
25 Notification of the new value of the allocable transtnission power to the
secondary systetn is carried out only in a case where the sum I,,& 4) of the
interference amounts to the prinlary system satisfies a formula below.
[0119]
lest (if,j ) > 'acceptable 9 ( 2 8 )
5 [0120]
Here, the Ilaceepfable(fi,,) in Formnla (28) represents the acceptable
interference aniottnt for the channel f, at the reference point i. Additional
determiaatioti like this makes it possible to further efficiently suppress increase in
signaling for notifying the allocable transmission power
10 [a1211
FIG. 7 is an explanatory diagranl illustrating an exeinplary configuration of
a secondary systetn tilanagelllent table 122 the storage unit 120 has in this
embodiment. With reference to FIG. 7, the secondary system management table
122 has five itenis of "chanlel number," "s)~stem ID" "acceptable transmission
15 power" "margin amount" "allocable transmission power" and "update date." The
"channel tlumber" is a nuillber to identify each of the secondarily usable frequency
channels. The "system ID" is an identifier to t~niquely identify the secondary
systetn. A device ID of the tnaster node 200 of the secondar)~s ystein may be used
as the systeln ID. The "acceptable transmission power" represents a value of the
20 acceptable transmission power corresponding to the allocable transmission power
notified to each secondary system. The "margin amount" represents a value of the
margin Z which is renloved froin the value of the acceptable transmission power
upon deciding the allocable transinission power notified to each secondaty system.
The "allocable transcnission power" represents a value of the allocable trans~nission
25 power notified to each secondary s~~ste~Tnh.e "update date" represents a date when
each record in the secondary systeni managemellt table 122 is npdated.
[0122]
In a case where the notification condition as described above is satisfied, the
notification unit 150 notifies each secondary system of the value of the allocable
transrnlission power to update the "acceptable transmission power," "margin amount,"
allocable transmission power", and "update date" in the seconda~y systeln
management table 122. Then, these itellis of data in the secolida~y systeln
management table 122 are referred to upon next determination of the notification
5 condition by tlie notification unit 150.
[0123]
[3-2. Flow of process]
Next, an explailation will be given of a flow of process by the
conimunication control device 100 according to this embodiment using FIG. 8 to FIG.
10 11.
[0 1241
(1) Power adjustnient processing
FIG. 8 is a flo\\.chart illustrating an example of flow of the power
adjustment processing by the communication control device 100. With reference to
15 FIG. 8, first, the power distribution processing is performed by the power distribution
unit 140 according to any of the methods sho\\ln in FIG. 6A to FIG. 6C (step S100).
The processes at steps S130 to S180 thereafter are repeated with ~espect to each
secondary system.
[0125]
20 At step S130, the notification tunit 130 focuses on one secondaly systetn
(hereit~after, referred to as a target system) to perform the power notification
determiaation processing (step S130). An explanation will be further given later of
an example of detailed flow of the power notification detertnination processing of
this step. If it is detennitled in the power notification detertnination processing that
25 the target system is not notified of the allocable transmission powel; the subsequent
processes are skipped (step S140).
101261
If it is detemiined in power notification detertni~iatiotlp rocessi~~thga t the
target system is notified of the allocable transinission power, the notification unit 130
30 performs the message generation processing to generate the power notification
tilessage directed to tlie target systeln (step Sl60). Then, the notification unit 130
transmits the generated power notification message from tlie cornmanication unit 110
to the target system (step S170). Further, the notification tinit 130 updates the data
for the acceptable tiatis~nissio~plo wer of tlie target systetn, margin amount, and
allocable transmission pomer stored in the secondary systetn maliagelnent table 122
5 (step Sl8O).
[0 1271
When these processes are cotnpleted for all the secondary systems (or all the
active secondary systems), the power adjusttnent processing shown in FIG. 8 ends.
[0128] . -
10 (2) Power notificatiot~d eterminatiol~p rocessing
FIG. 9A is a flowcha~t illustrating a first example of detailed flow of the
power llotificatioli determination processing corresponding to step S130 in FIG. 8.
[0 1291
With reference to FIG. 9A, first, the notificatioli unit 150 detennines
15 whether or not the target system is the newly appearing secondary system (step
S131). Here, if the target system is the newwdy appearing secondary system, the
notification unit 150 detertilines that the target system is notified of a new allocable
transmission power (step S136). On the other hand, if the target system is the
existing secondary system, the process proceeds to step S132.
20 [0130]
At step S132, the notification unit 150' acquires the value PDrSprocfv tlle
allocabletra~~s~llisspioown er which is previously notified to the target systelnfioln
the secondary system management table 122 (step S132). Then, the notification
unit 150 uses the value P,,,,,,, of the acceptable transmission power which is newly
25 distributed to the target system by tlie pomer distribution unit 140 and the value
Ph,pmvo f the allocable transmission power which is previously notified to determines
wwrhether or not the notification condition described above is satisfied. For example,
in a case of Pt,np,neling the allocable transmission power can be fiii.ther reduced.
The communication control device 100 may hold also a minimum value of a
requested transmission power for each seconda~y system and exclude the target
system of which the allocable transmission power falls below the minimum value of
the requested transmission power ft.0111 the power allocation targets.
20 [0137]
Note that an event as a trigger of the power adjustment processing
illi~stratedi oFIG. 8 typically iialudes three kinds ofe vents Ev1 to Ev3 below.
Evl) Increase in the number of the secondary systems
Ev2) Decrease in the number of the secondary systenns
Ev3) Move of the secondary system
A~nong them, in a case of the event Evl, since the allocable transmissioa
power for tlie existing secondary system does not increase typically, tlie
determination at step S134 in FIG. 9A or step S134 and S135 in FIG. 9B may be
omitted. Similarly, in a case of the event Ev2, since the acceptable tmnsmission
30 power for the existing secondary system does not decrease typically, the
determination at step 5133 in FIG. 9A or FIG. 9B may be omitted. The event Ev2
riiay be recognized by an explicit notification of detacluner~t from the secondary
system or recognized by not receiving a signal from the secondary system (e.g.,
beacon) which is monitored with a cycle able to be registered in advance. If the
periodical signal from the secondaiy system is not received, the event Ev2 may be
5 determined to occur aftera fi~rtherp redetermined waiting time lapses. This makes
it possible to prevent uriilecessary signaling from occurring which is due to the
increase or decrease of the secondary system in a case where the master node of the
secondary system temporarily tarns off or sleeps.
[0138]
10 (3) Message generation processing
FIG. 10 is a flowchart illustrating an example of detailed flow of the
message generation processing corresponding to step S160 in FIG. 8.
[0139]
With reference to FIG. 10, first, the notification unit 150 removes the margin
15 Z from the value P,,,p,n,,, of the acceptable trans~nissio~pto wer which is newly
distributed to the target system by the power distribution unit 140 to decide the value
of the new allocable transmission power Pb,ne,, (step S161).
[0 1 401
Next, the notification unit 150 determines whether or not the target syste~n
20 is the newly appearing seco~~dasrys tem (step S162). Here, if the target system is
the newly appearing secondary system, the process proceeds to step ,3165. On the
other hand, if the target. system- is the existing secondaiy system, the process
proceeds to step S 163.
[0141]
25 At step S163, the notification unit 150 calculates a difference value dPb =
P,,,,, - P,,,, of the allocable transtilissio~i power (step S163). Further, the
~lotificatiou~nl it 150 quantizes the calculated difference value dP,, by use of the unit
of update p,,,it (step S164). On the other hand, at step SI65 the notificatiotl unit 150
quantizes the value P,,,,, of the new allocable transmission power by use of the unit
30 of update p,,,,it (step S165).
[0 1421
Then, the notification unit 150 generates the power notification message
which, for example, inclltdes a field indicating the quantized allocable transmission
power value (difference value in the existing secondary system) and is directed to the
address of the master node 200 of the target system (step S166).
5 [0143]
The power notification message generated in this way is trat~smitted from
the cotntnu~~icaticoo~nlt rol device 100 to the master node 200 of the target systetn at
step St70 in FIG. 8.
[0144]
10 (4) Additional determination processing
FIG. 11 is a flo\vchart illustrating an example of flow of a determination
processing for determining the accumulative interference amount using Formola (27)
and Formula (28) described above. Such a determination processing may be
performed in addition to the power notification detertnination processing at step
15 S130 in FIG. 8.
[0145]
With reference to FIG. 11, first, the notification unit 150 acquires the value
Pt,,,,, of the allocable transmission power which is newly distributed for the new
secondary system (step S151). Additionally, the notification unit 150 acquires the
20 value Ph,p,e. of the allocable transmission power which is previously notified to the
existing seconda~ys ystem (step S 152). Next, the notification unit 150 estimates the
sun1 I, of the interference amoutlts to the primaly system in accordance with
Formula (27) (step S153). Then, the tlotification unit 150 detennines whether or
not the estimated sum I,,, of the interference amounts violates the acceptable
25 interference amount lacceptable of the primary system (step S154). Here, if the
estitnated sutn IeSt of the interference amounts violates the acceptable interference
amount Iscceptablteh, e notification unit 150 determines that each of the existing
systems is notified of the value of the new allocable transmissio~p~o wer (step S155).
011 the other hand, if the estimated sum Iesl of the interference atnotutlts does not
30 violate the acceptable interference amoutlt Iscceptablet,h e notification unit 150
determines thatthe existing system is not notified of the value of the nem allocable
transnlission power (step S156).
[0146]
[3-3. Distance between primary systeln and secondary system]
In the power distribution processing described above, a distance behveen the
5 primaly system and the secondary systeln is required to be decided in order to derive
the path loss for each secondary system. The distance between the pritnary systeln
and the secondary systeul~~nabye defined in accordance with, for exatnple, any of
exanlples described belolv.
[0147]
10 (1) First exatnple
In a first example, the distance between the primary systenl and the
secondal-jr system is the shortest distance from a position of each secondary system to
a periphery of the service area for the prilnary syste~n.
[0148]
15 For example, FIG. 12A shows the boundary 12 corresponding to the
periphery of the service area for the primary system and four secondary systems. A
first, second and third secondary systems are located outside the service area for tile
primary systenl. The shol-test distances fionl the first, second and third secondary
systems to the periphery of the service area for the primary systenl are d01, d02, and
20 d03, respectively. 011 the other hand, a fourth secondary system is located inside
the service area for the primary system. When deriving the path loss concenling the
~ fourth secondary system, the distance between the primaly systenl and the secondary
systeln may be considered to be zero. In that case, the path loss beconles the largest.
Instead; the shortest distance from the fourth secondarj~sy stenl to the boundary 12 is
25 dealt with as a distance between the priniary systeln and the fouilh secondary system.
[0149]
(2) Second example
In a second example, the distance between the prilnary system and the
secondary systeeln is a distance fi.0111 a position of each secondary systenl to a certain
30 point on or inside the periphery of the service area for the primary system. The
certain point nlap be, for example, a point on the periphery of the service area for the
primary system which is the closest to a secondary spstein. 111 addition, the certain
point tnay be, for example, a point having the smallest sum of distances from a
plurality of secondaly systems. This point is thought to be a position located by a
virtual reception station of the primaly system suffering the interference eon1 the
5 secondary system.
[0150]
For example, FIG. 12B shows again the bounda~y 12 and four secotldary
systems. The first, second, and third secondary systems are located outside the
service area for the primary system. Here, given that a point on boundaty 12 the
10 closest to the first seconda~ys ystem is PI. The distances behveell the first, second,
and third secondary systems and the primary system correspotid to distances dll,
d12, and dl3 between each position of the first, second, and third secondary systems
atld the point PI, respectively. On the other hand, the fou~th seco~idary system is
located inside the service area for the primary system. When acquiring the path loss
15 co~wer~linthge fourth secotldary system, similarly to the first example, the distance
between the pritnary system and the secondary system may be considered to be zero.
Instead, a distance between the fourth secondarj~s ystem and the point P1 may be
dealt with as the distance between the primary systetn and the fourth secondaty
system.
20 [0151]
In FIG. 12B, a point P2 is a point on the bouodaiy 12 having the smallest
sum of the distances from the first, second, and third secondary systems. The point
P2 like this may be used in place of the point P1. Note that, for example, in a case
where Inally of the secondary systems are located far from the guard area for the
25 pri~narps ystem, where it is known that the primary reception station exists only in a
narrow geographical area, where the acceptable interference amoutit is considerably
severe at a certain point or the like, a certain point specified in advance tnay be used
as a reference point for distance calculation. Additionally, in a case where plural
different acceptable interference amounts are regulated for each tnodulation system,
30 the reference point may be selected taking into account not only the distance but also
the modulation systetn or the plural-acceptable interference amounts.
[OI 521
In comparison of the first example and the second exatnple, in the case of
the first example, the distance calculatio~i~s easy wvl~ilea value of the path loss is
possibly estitnated to be excessively small. For example, such a sitnation ]nay
5 occur in a case where two secondaly systems are located with the primaly system
present therebetween. In that case, the transtnission power allocated to the
secondary systetn has a stnaller value. Therefore, it can be said that the first
example is low in calculation cost and inore secure definition in view of interference
prevention. On the other hand, in the second example, the value of the path loss is
10 less prone to be estimated to be excessively small, and chances of the secondary
usage can be more increased.
[0153]
(3) Third example
In the third example, the distance between the pri~nary system and the
15 secondary systenl is a distance from a position of each secondary system to the nnost
adjacent primary reception station. For example, FIG. 12C shows three secondaty
systems and three prirnary reception stations. A first prima~y reception station is
located the nlost adjacent to the first secondary system. Adistance between the first
secondaiy system and the first primary reception station is d21. A second primary
20 reception station is located the most adjacent to the second secondary system. A
distance behveen the secondary systenl and the second primaty reception station is
. d22. A third prima17 reception station is located the most adjacent to the thiscl
seconda~y system. A distance behveen the third secondary systenl and the third
primary reception station is d23. Therefore, d21 tnay be used as the distance
25 between the first secondary systeln and the primary system, d22 may be is used as
the distance beheen the second secondary systeln the primary system, and d23 may
be used as the distance between the third secondary systenl and the primary system.
[0154]
(4) Fourth exatnple
30 In a fourth example, the distance behveen the primary systenl and each
secondary system is a distance to the primary reception station having the stnallest
sun1 of distances from the positions of all secondary systems. For example, FIG.
12D shows again three secondary systems and three primaly reception stations.
Among them, the primary reception station having the smallest sum of distances
fronl the positions of three secondary systems is the second primary reception station.
5 A distance behveen the first secondary system and the second primary reception
station is d31. A distance behveen the secondary system and the second primary
reception station is d32. A distance between the third secondary system and the
secolld priinary reception station is d33. Therefore, d31 may be used as the
distance between first secondary system and the primary system, d32 may be used as
10 the distance between the second secondary system and the primary system, and d33
may be used as the distance between the third seconda~y system and the pritnary
system.
[0 1551
In the third and fourth examples, the actual position of the primary reception
15 station is used as the reference point for distance calculation, and thus, which allows
more practical interference amount estimation.
[0156]
In the exarllples in FIG. 12A to FIG. 12D, the explanation is mainly given of
how the reference point on the primary system side is to be set in calculating the
20 distance behveen the primary system and the secondary system. However, various
setting methods are possible concerning also the reference point on the secondary
. . . - . system side; For example, the positiotl of the reference point on the secondary. . . ~
system side may be simply the position of the master node 200 as a master of the
secondaly system. Instead, the position of the reference point on the secondary
25 system side may be, of the nodes of the secondary system (master node and slave
node), a position of the node closest to gnard area for the primary system or any of
the primary reception stations. I11 addition, althoagh the calculation is complicated,
a plurality of distances may be calculated based on the positions of the plural nodes
of the secondary system to calculate a eo~nprehensive path loss in accordance wit11
30 the relevant plurality of distances. These setting methods of the reference point on
the secondary systenl side may be respectively combined with any of the setting
tnethods of the reference point on tlie primary ssystetn side illustrated in FIG. 12A to
FIG. 12D.
[0157]
Fut-thel; for example, the reference point on the secotidary syste~ns ide may
5 be set in a stepwise lnanner as below. First, the reference point on the secondary
systetn side is tetnporarily set to the master node 200 as a master of the secondary
system. Next, one point on the periphery of the service area for the primary systetn
the closest to the master node 200 or a positioil of the primary reception station the
closest thereto is set to the reference point on tlle primary systeln side.
10 Subsequently, the interference given to the above reference poitit on tlie primary
system side is estimated for each of the nodes of the secondary systetn (master node
and slave node). Then, the position of the node on the secondary systetn side to
give tlie ~naxiri~uin~tner ference to the above reference point 011 the primary system
side is set to the final reference point on the secondary systeln side. In estimating
15 the interference for each node of the secotidary system, different transmission powers
tilay be cotisidered depending on kinds of nodes (tnastes node or slave node).
[0158]
[3-4. Si~uplificationo f term of interference between channels]
In the first exatnple described above of the power distribution l~rocessingb y
20 the power distribution unit 140, the term evaluating the interference between
chamlels may be replaced with a fixed or variable tnargin arnoutlt, Given that a
margin an~outlti n the.channe1 f, is Rintj,F ornlula (13) to Fortnula (15) described- . . . . . .. ~
above may be converted into Formula (29) to For~llula( 3 1) shown as below.
[0159]
Iaccqtab, ('9 f j ) Mj i' = arg min
i
- C p 1 ( f j 9 k ) . ~ ( i , f j , k ) . ~ ( f , , k )( 3 0 )
'In[j, k=l 1
[0 1601
Forn~ula (29) to Fortllula (31) above nlean that the interference between
chalinels fro111 each secondary systenl to the prinlary system is evaluated using a
5 simplified method which does not depend on the path loss of each secondary system.
A margin amount Rintj may be typically set depending on the ~lumbek of the
secondary systems using the adjacent channel to the channel 4. For example, in the
next exatliple of Formala (32), the niargin a~no~nRltin tj is equal to the sunl of the
nunibers of the secondary systems using the adjacent channel. In an example of
10 Fornlula (33), \veighting is applied depending on the loss co~nponent H fiam the
adjacent channel. In an exan~pleo f Formula (341, the loss component H is replaced
nrit11 a weight coefficient yj (for-example, the larger an interval between the chant~el :. '. -
becomes, the smaller value tile weight coefficient yjj nlay be set to).
[0161]
[0 1621
As a result of replacing the tern1 of the interference between channels like
this, the nlove of the secondary systenl which secondarily uses a channel causes low
5 variability of the acceptable transmission power distributed to the secondaly systenl
. which secondarily uses the adjacent channel to the relevant channel. This allo\vs
the notification condition described above to be less frequently satisfied to suppress
the increase in signaling.
[0163]
10 Further, in Fornlula (32) to Forl~li~(l3a4 ), with respect to the nulnber N:, of
secondary systetns concerning each adjacent chatmel, the actual nulnber is replaced
with a notninal number N;. The t~o~ninanla mber N; of secondaty systems
- concerning each adjacent channel. is not-updated until an update condition below is , .
satisfied, for example.
15 [0164]
or
[0 1651
If it is deter~nine? that the actual number N:, of secondary systems and the
20 nolnillal number N':, of seconda~ys ystetns concerning each adjacent channel satisfy
the above update condition, the no~ninal n~rniber N',, of secondary systems may be
updated in accordance with any of forn~ulass hown below. Here, parameters dN1,
dNz, dN, in each formula are additional parameters which may be defined in advance.
[0 1661
N'.. +N1..+c.dN, ( 3 s ) ~ JJ JJ
[0 1671
The update of the llotninal nnmbe~N ; of secondary systems concerning
each adjacent chant~enl lay be carried out, for example, by the power distribution unit
140 after step S102 in the flowchart of FIG. GA. h~troduction of the nonlinal
10 number NIi of secondary systetlls like this causes that the margin atllount Rintj for
evaluating the interference between channels does not completely follow the actual
number of the secondary systenls and varies aRer waiting for the update of the
no~ninatli urnber N'J of secondary systems. Therefore, increase and decrease in the
nuniber of the secondarj~ systenls n~hicli secondarily use a channel causes low
15 variability of the acceptable trans~nissionp ower distributed to the secondary systenl
which secondarily uses the adjacent chanr~el to the relevant channel. As a result,
the notification condition described above can be further less frequently satisfied.
[0168] .... ..
. . , . . -
<4. Exemplary configuration of master node>
20 FIG. 13 is a block diagrail~ illustrating an exe~nplary configuration of the
master node 200 which is a commnnication device operating the secondary syste111
by use of the transtnission power allocated to the co~nt~~unicatcionnt rol device 100
described above. With reference to FIG. 13, the master node 200 includes a
communication unit 210, control unit 220, storage unit 230, and wireless
25 co~nmunicationu nit 240.
[0169]
The co~n~nunicatiounn it 210 operates as a con~~~~utlicaitnitoenrf ace for
corn~ii~tnicatiobne tween the data server 30 and the communication colitroi device
100 by the master node 200. The commt~nicationu nit 210, tl~tdera control by the
control unit 220, transmits infor~llationo n the secolidaty systenn to tlie data server 30,
for example, at the start of the secondary usage. Additionally, the com~llunication
5 unit 210 receives information notified fro111 the data server 30. Moreover, the
colnmunication unit 210 tra~is~iliatnsd receives a request for interference control and
acknowledge to and frotn the co~ut~iunicaticoo~lit~ro l device 100. Furthel; the
com~nuuication unit 210 receives tlie power notification message from the
cotntnu~iicationc olitrol device 100 to output the received message to the control unit
10 220.
[0170]
The control unit 220 has a f~~nctioton control general operation of the
master node 200. For example, tlie co~ltrol illlit 220 cooperates with the
co~il~n~~~iicoattiitroonl device 100 in the sequence illustrated in FIG. 4 to suppress
15 the interference to tlie primary system in operating tlie secotidary system. More
specifically, the control unit 220 refers to the value of the allocable tra~islilissio~i
power indicated by the power notification message received fro111 the colnlnanication
control device 100. Then, tlie cotitrol unit 220 sets the transmission power falling
within a range of the allocable transmission power to the wireless cotn~nu~iication
20 unit 240 for operating the secondaly system. The control unit 220 may further
distribute the allocable trans~nission power among the tiodes participating in
secondary system, for exa~~iple.
[0171]
The storage unit 230 uses a storage media111 such as a hard disk or
25 semiconductor tnetnory to store a program and data used for cooperation with the
communication co~ltrodl evice 100 and operation of the secondaiy system.
[0 1721
The wireless communication unit 240 operates as a wireless communication
interface for wireless communication between the master node 200 and the slave
30 nodes connected with the relevant master node 200. The wireless co~n~~~u~~ication
unit 240 tratistnits and receives a wireless signal to and from one or more slave nodes
ill accordance with lEEE802.22, IEEE802.llaf, or ECMA-392, for example. The
tralismission power of the wireless signal transmitted by the wireless communication
unit 240 may be controlled within the above described range of the allocable
transtnissio~pl ower by the control unit 220.
5 [0173]
( 5 . Explanatory ~nodificatio~l> .. .
In this description, the expla~iationh as been given of mainly the examples in
which various calculation processes for adjusting the transtnission power for the
seconda~ys ystem are performed by the communication control device 100 having a
10 fi~~ictioans the secondary system manager As explained regarding FIG. 3, the
communication co~itrodl evice 100 may be mol~ntedo tl the physically same device as
the data server 30 or any of the master nodes 200. Moreover, a part of the
calculation processes described above may be perfanned on the physically different
device.
15 [0174]
For example, besides a first device carrying out relatively complex
calculation on the basis of tlie interference control model described above, a second
device carrying out simple parameter calculation may be provided. In this case, the
second device may carry out acquisitiotl of the distribution margin MI, acquisition of
20 the safety margin SM, calculatio~o~f the allocable transmission power from the
acceptable tra~~s~nisspiown er, or calculation of the difference value of the allocable
transmission power and quantization thereof, for example. The seco~ld device,
instead of using the fixed distribution margin MI, may calculate tlie distribution
margin MI, for example, in accordance with any of calculatitlg formulas below
25 depending on tlie number of the secondary systems.
[0 1751
of the acceptable tratis~nissionp ower whicli is ncdy distributed. According to such
a configuration, in the case where the interference amount to the primary systeln
possibly exceeds the acceptable interference amount, the value of the new allocable
transmission power is notified to the secondary system. Therefore, tlie accutiiulated
5 interferences fro111 a plurality of seconda~ys ystems are prevented fiom giving the
negative influence to the primary system.
[Ol 801
In addition, the above notiticatiot~c ondition may include a condition that a
difference obtained by subtracting tlie value of the allocable transtuission power
10 which is previously notified from the value of the allocable translliission power
which is newly decided is larger than a predeter~niiledth reshold. According to such
a configuration, in the case where the acceptable tralls~nission power increases, the
allocable transmission power for the seconda~y systeln is maintained until tlie
increasing width thereof exceeds a predetermined threshold. Therefore, tlie
15 signaling increase prevention may be balanced with communication chance increase
due to rise of the allocable transmission power.
[0181]
Moreover, the secondary systeln manager recotiimends the channel for
secondary usage to the secondary syste~isl uch that, in adjt~st~neonft the transmission
20 power which is brought about in the future, possibility for considerably varying the
value of the acceptable transmission power is reduced and the signaling can be
prevented from increasing.
[0 1 821
Note that a series of control processes by the respective devices explained in
25 this description may be achieved by any of soft\vare, hardware, and cotnbinatioi~o f
software and hardware. Programs co~lstitutingth e software are stored in a storage
medium provided inside or outside each device in advance, for example. Then,
each progratil is, for example, read illto a RAM (Random Access Memory) lien
executed to be executed by a processor such as a CPU (Centla1 Processing Unit).
30 [O183]
The preferred embodiments of the present invention have been described
ahove with reference to the accompanying drawings, nlhilst the present invention is
not limited to the above examples, of course. A person skilled in the art tilay find
various alternations and modifications within the scope of the appended claims, and
it sl~ouldb e ltnderstood that they will natllrally come under the technical scope of the
5 present invention.
[0 1841
Additionally, the present technology may also be configured as belo\\,.
(1)
A commanication control device inclading:
10 a power distribution onit configarcd to distribute, to one or more secondaly
systems, a transmission power accepted for a secondary usage of a frequency channel
which is protected for a primary system; and
a notification unit configt~redt o notify each secondary systen~o f a value of
a second transmission power which is decided depending on a value of a first
15 transmission powver distributed by the power distribution unit,
wherein, t~pon updating the transnlission power, only in a case where a
value of the second transmission power which is previously notified auld a value of
the first trat~s~nissiopno wer which is newly distributed by the power distribution unit
satisfy a predeterli~ined condition with respect to a certain secondary system, the
20 notification unit notifies the secondal~y systenl of a new value of the second
tratls~nissiop~ol wer.
(2)
Tl~c cotnm\~nication control device according to (I), wherein the
predetermined condition includes a condition that the value of the second
25 transiilissioil power which is previously notified is larger than the value of the first
transmission power which is newly distributed by the power distribution unit.
(3)
The comn~onication control device according to (1) or (2), wherein the
predetermined condition includes a condition that a difference is larger than a
30 predetermined threshold, the difference being obtained by subtracting the value of
the second t~ansmission power which is previously notified frotn the new value of
the secoitd transnlission po\ver decided depending on the vali~c of the first
transtnission power which is newly distributed.
(4)
The communication control device accorditlg to any one of (1) to (3),
5 wherein the value of the second transtnission power is decided by relnovitlg a
predetermined margin fro111 the value of the first transtnission power.
(5)
The co~nmunication control device according to any one of (1) to (9,
wherein it1 a case where the new value of the second transmission power which
10 distributed to an existing secondary systelil is larger than the tmaximum value of the
trauslllission power capable of being output in the secotldary system, the notificatioil
unit does not not if)^ the secondary systelll of tlie new value of the second
transmission powel:
(6)
16 The communication control device according to any one of (1) to (5),
wherein the power distribution unit carries out distribution calculation of the first
transtnission power in response to events including change in the nuniber of the
secondary systenis or move of the secondary system, or periodically.
(7)
20 The comtnunication control device according to any one of (1) to (6),
wherein, upon updating the transmission power, the notification unit filrtlier
colllpares a sum of interference amounts to the primary spstetn on a basis of a value
of an allocable trans~nissionp o\ver across the one or more secondary systelns with aa
acceptable interference amount of the primary system, and notifies the existing
25 secondaly system of the new value of the second transtnission power only in a case
where the suln of the interference amounts violates the acceptable interference
amount.
(8)
The conlmonication control device according to any one of (1) to (7),
30 wherein the notification unit notifies each secondary systeni of the new value of the
second transmission power by signaling a difference value frotn tlie previous
notification of the second trans~nissionp ower.
(9)
The cominonication control device according to (S),
wherein the valne of the second transmission po\jrer is discretely updated in
5 terms of integral ~nultipleo f a predetern~inedu nit of update, and
wherein the notification unit signals the difference value quantized by use of
the predetermined unit of update.
(10)
The communication control device according to any one of (1) to (9),
10 wherein the power distribution unit distributes the translnission pomer to tlle one or
Inore seconda~ys ystetl~sb y evaluating an interference between channels from each
secondary system to the pritna~y systenl using a siniplified method wliich does not
depend on a path loss of each secondary system.
(11)
15 The communication colltrol device according to (lo), \vherein the power
distribution unit evaluates the interference between channels from each secondary
system to the prima131 system using the number of nolllinal secondary systenls which
does not conlpletely follow the number of actual secondary systems for each channel.
(12)
20 A coii~~nunicatiocnon trol inethod including:
distributing, to one or tnore secondary systems, a transinission power
accepted for a secondary usage of a frequency channel which is protected for a
primary system; and
notifying each secondary system of a value of a second transmission power
25 which is decided depending on a value of a first transmission power distributed by
the power distribution unit,
\\rilerein, upon updating the transmission powel; only in a case where a
value of the secotld transmission powel \\~hicIi is previously notified and a value of
the first transnlission power which is newly distributed satis@ a predeterniined
30 condition with respect to a certain secondary system, the secondary system is notified
of a new value of the second transmission power.
(13)
A communication control systetn including:
a cotnmunication control device iilcluditlg
a power distribution unit configured to distribute, to one or mote
5 secottdary systems, a transmission power accepted for a secondary usage of a
frequency channel which is protected for a primaty system, and
a notification unit configured to notify each secondary systelil of a
value of a second transmission power which is decided depending on a value of a
first transtnissiori power distributed by tlie power distribution unit; and
10 a communication device configured to set a transinission power for
operating the seco~idaty systetn within a range of the value of the second
transmission power notified fro111 the communication control device,
wherein, upon updating the transn~issioti power, only in a case where a
value of the second transmission power which is previously notified to the
15 comniunication device and a value of the first tratistilission power which is newly
distributed to tlie communication device satisfy a predetertilined condition, the
notification unit of the communication control device notifies the cominunication
device of the new value of the second transmission power
Reference Signs List
Comtnunication control systetn
Prin~arytr ansmission station
Primary reception station
Commi~nicationc ontrol device
Power distribution unit
Notification unit
Master node of secondaty systetn
The communication control device according to claim 1, nrherein the valuc
of the second transmission power is decided by removing a predetermined margin
from the value of the first transmissio~pl ower.
5 Claim 5
The cotnmunicatio~lc ontrol device according to claim 1, wherein in a case
where the new value of the second transmission power which distributed to aa
existing secondary system is larger than the maximum value of the transmissio~l
power capable of being output in the secondary system, the notification unit does not
10 notify the secondary system ofthe new value of the second transmission power.
Claim 6
The communication co~itrold evice accordi~igto clai~ii1 , wherein the power
distribution anit carries out distribution calculatioli of the first transmission power in
15 response to everits including change in the number of tlie secondary systems or move
of the secondary system, or periodically.
Claim 7
The commu~lication control device according to claim 1, wherein, upon
20 updating the trans~iiissionp ower, the notification unit further compares a sum of
interference amounts to the primly system on a basis of a value of an allocable
tra~islilissio~pol wer across tlie one or more seconda~ys )~stemsw ith an acceptable
interference amount of the primary system, and notifies the existing secondary
system of the new value of the second tra~lsmissiotp~o wer only in a case where the
25 sum of the interference amounts violates the acceptable interference amount.
Claim 8
The communicatioti control device according to claim 1, wherein the
notification unit notifies each secondary system of tlie new value of the second
30 transmission power by signaling a difference value from tlie previous notification of
the second traos~nissionp ower,
Claim 9
The communication control device according to claim 8,
wherein the value of the second transmission power is discretely updated in
5 tenns of integral multiple of a predetermined unit of update, and
wherein the notification unit signals the difference value quantized by use of
the predetermined unit of update.
Claitn 10
10 The communication control device according to claim 1, wherein the power
distribution unit distributes the t~anstnissioll power to the one or Inore sccondaly
systelns by evaluating an interference behveen channels from each secondary systeni
to the primary system using a si~nplified method which does not depend on a path
loss of each secondary system.
15
Claim 11
The communication control device according to clainl 10, wherein the
power distribution unit evaluates the interference behveen channels fro111 each
secondary system to the pri~narp system using the number of nominal secondary
20 systelns which does not colnpletely follow the nutnber of actual secondary systelns
for each channel.
Claim 12
A conlnlunication control n~ethodc omprising:
25 distributing, to one or inore secondary systems, a transmission power
accepted for a secondaty usage of a frequency chat~nel which is protected for a
primary systeru; and
notifying each seconda~y systenl of a value of a second transmission power
which is decided depending on a value of a first transtnissioll power distributed by
30 the power distribution unit,
wherein, upon updating the translnissioll power, only in a case where a
CLAIMS
Claim 1
A cotnmunication control device comprising:
a power distribution unit configured to distribute, to one or Inore secondary
5 systems, a transmission power accepted for a secondary usage of a frequency channel
which is protected for a primary system; and
a notification unit configured to notify each secondarp system of a value of
a second transnlission power which is decided depending on a value of a first
trans~nissionp ower distributed by the power distribution unit,
10 \vherein, upon updating the trans~nission powel; only in a case where a
value of the second transnlission powver which is previously notified and a value of
the first transmission power which is nelvly distributed by the power distribution unit
satisfjr a predetermined condition with respect to a certain secondary system, the
notification unit notifies the secondary system of a new value of the second
15 translnission power.
Claiin 2
The communication control device according to clai~n 1, wherein the
predetermined condition includes a condition that the value of the second
20 transmission power which is previously notified is larger than the valne of the first
transmission power which is newly distributed by the power distribution unit.
Claim 3
The conlrnl~nication control device according to claim 1, wherein the
25 predetermined condition includes a condition that a difference is larger than a
predetermined threshold, the difference being obtained by subtracting the value of
the second transmission power which is previously notified from the new value of
the second transmission power decided depending on the value of the first
transmission power which is newly distributed.
30
Claim 4
value of the second trans~nissiop~o~w cr \\~lriclii s pre\rious!y iiotified atid a value of
tlie first transniission power which is newly distributed satis& a predetermined
condition with respcct to a certain secondary system, the seco~itlarys yste~nis notified
of a value of tlie second transmission power.
5
Clailil 13
A communication control syste~nc omprising:
a coni~niunicationc otitrol device inclutling
a po\ver distribution unit configoren to distribute, to one or inore
10 secondary systems, a transmission powcr accepted for a secondary usage of a
frequency cliannel \vliich is protected for a primary system, and
a notification unit configured to notify each secondary system of a
value of a second tralismissiot~ po\\7er \~rhicli is decided depending on a value of a
first transmission power distributed by the po\Trer distribution unit; and
15 a communicatio~i device configured to set a transmission powcr for
operating tlie secondary systeni ~vithiu a range of the value of the secoild
tra~ismissionp ower notified fiom the comri~~~nicatcioont rol device,
\vIierein, upon updating the transmission po~\~eeol;n ly in a case ~~111erae
value of the second transmissiotl po\\,er \vliich is previously notified to the
20 conitliunication device and a value of tlie first trans~uissionp ower v\~hichi s ne\\~ly
distributed to the communication device satisfy a pretlctern~ined co~lclition, the
notification unit of tlie coml~iunication control device notifies the communication
device of the ilew value of the second transmission power.