Document Name] DESCRIPTION
[Ti t le of Invent ion]
WIRELESS BASE STATION, TRAFFIC LOAD-BALANCING
METHOD, AND STORAGE MEDIUM WITH PROGRAM STORED
THEREO5 N
[Technical Field]
[0001]
The present invent ion relates to a radio base stat ion, a traff ic load
distr ibut ion method, and a storage medium storing a traffic load
10 distr ibut ion program, that dist ributes t raffic loads among base stat ions .
[Background Art]
[0002]
A backhaul (hereinaf ter, refer red to as a mobi le backhaul) between
radio base stat ions and a mobi le core network may include a plural i ty of
15 l inks. Fig. 10 is a block diagram i l lust rat ing one example of the mobi le
backhaul . The mobi le backhaul is divided into an access l ink, an
aggregat ion l ink, and a met ro l ink. The access l ink is a l ink that
accommodates a radio base stat ion connected to a relay apparatus disposed
in an access area. The aggregat ion l ink is a l ink that accommodates a
20 plural i ty of radio base stat ions connected to relay apparatuses disposed in
the access area and a radio base stat ion (no t i l lust rated in Fig. 10) disposed
in an aggregat ion area. The metro l ink is a l ink in a met ro area and is a
l ink to t ransfer a large amount of mobi le data t raffic of the plural i ty of
radio base stat ions t ransfer red via the aggregat ion l ink to a mobi le co re
25 network. Hereinafter, a communicat ion resource in the backhaul wi l l be
refer red to as a backhaul resource. Fur ther, a traffic load in the backhaul
resource wi l l be referred to as a backhaul resource load.
[0003]
As a method for dist ribut ing backhaul resource loads, there is, for
2
example, MLB (Mobi l i ty Load Balancing) executed between eNBs
(evolved Node Bs) . The eNB is a radio base stat ion corresponding to LTE
(Long Term Evolut ion). MLB is executed in accordance wi th procedures
indicated in 1 to 4 described below.
[00045 ]
1. Via an X2 l ink between eNBs, there is executed resource status
report ing processing, specifical l y, Resource Status Repor t ing Ini t iat ion
Procedure descr ibed in technical speci ficat ions (TS 36.423 Version 11.5.0)
of 3GPP (3rd Generat ion Partnership Project) .
10 [0005]
Fig. 11 is a sequence diagram i l lust rat ing resource status report ing
processing between eNBs. In the resource status report ing processing, as
i l lust rated in Fig. 11, a resource status request message (X2: RESOURCE
STATUS REQUEST message) is t ransmi t ted f rom an eNB 1 to an eNB
15 adjacent thereto (hereinafter, refer red to as an adjacent eNB), i .e. an eNB 2.
Then, f rom the eNB 2 to the eNB 1, a response message (X2: RESOURCE
STATUS RESPONSE message) to the resource status req uest message is
transmi t ted.
[0006]
20 Fig. 12 is an i l lust rat ive diagram i l lustrat ing a st ructure of the
RESOURCE STATUS REQUEST message. The eNB 1 designates load
informat ion of the adjacent eNB (eNB 2) that establ ishes an X2 l ink as a
measurement object in the RESOURCE STATUS REQUEST message.
S p e ci f i c al l y, as i l l u s t r at ed i n Fi g . 1 2 , t h e eNB 1 d es i g n at es “TN L
25 ( Tr an s p o r t Netwo r k La ye r ) l o ad In d P e r i o d i c” as t h e p ar amet er “R ep o r t
Ch a r a ct e r i s t i cs (me a s u r emen t o b j e ct i t ems ) ” o f t h e RESOURCE STATUS
REQUEST message. Thereby, the eNB 1 becomes able to periodical ly
receive load informat ion of the eNB 2. It should be noted that in “R ep o r t
Ch a r a ct e r i s t i cs , ” u p t o f o u r p i e c es o f l o a d i n f o rmat i o n c a n b e d es i g n at e d .
3
In t h e p r es en t ex amp l e , as o n e t h e r e o f , “TNL l o ad In d P e r i o d i c” i s
included.
[0007]
2. The eNB 1 receives a resource status update message (X2:
RESOURCE STATUS UPDATE message) f rom the adjacent eNB5 .
[0008]
Fig. 13 is an i l lust rat ive diagram i l lustrat ing a st ructure of the
RESOURCE STATUS UPDATE message. The RESOURCE STATUS
UPDATE mes s a g e r e c ei v ed b y t h e eNB 1 i n cl u d es “S 1 TN L Lo ad
10 In d i c at o r ” as i l l u s t r at ed i n F i g. 1 3 . “ S 1 TN L Lo ad In d i c at o r ” i s l o a d
informat ion of an S1 transpor t network layer (hereinafter, referred to as S1
network load informat ion) . The S1 network load informat ion is
informat ion indicat ing a backhaul resource load of a l ink, i .e. an access
l ink between an eNB and a fi rst -hop relay apparatus from the eNB. A
15 value of the S1 network load informat ion is indicated by any one of four
stages o f “ Low Lo ad , ” “Med i umLo ad , ” Hi g h Lo ad , ” an d “Ov e r l o ad . ”
[0009]
3. The eNB 1 changes, when a load of TNL exceeds a certain
threshold, a handover at t ribute value (a value of a parameter for
20 control l ing Handover described in the technical specif icat ions) t o swi tch a
cel l where a radio terminal is located f rom a cel l of the eNB 1 to a cel l of
an adjacent eNB having a low load, i .e. to execute Handover. At that
t ime, the eNB 1 designates the cel l of the adjacent eNB having a low load
as a handover dest inat ion on the basis of the S1 network load informat ion
25 received from the adjacent eNB. Herein, i t is assumed that the eNB 1
designates a cel l of the eNB 2.
[0010]
4. The eNB 1 handovers the cel l where the radio terminal is located
from the cel l of the eNB 1 to the cel l of the eNB 2 to dist ribute backhaul
4
resource loads.
[0011]
PTL 1 describes a technique in which in a radio communicat ion
system where an eNB communicates using a plural i ty of car r iers, the eNB
exchanges car rier configurat ion informat ion, load i nformat ion, and 5 a
resource usage status wi th another eNB to avoid inter -cel l interference and
execute load distribut ion among carriers.
[Ci tat ion List]
[Patent Li terature]
10 [0012]
[PTL 1] Internat ional Publ icat ion No. WO2011/052643
[Summary of Invent ion]
[Technical Problem]
[0013]
15 Here, i t is assumed that the eNB 1 and the eNB 2 use access l inks
differing from each other. Further, i t is assumed that aggregat ion l inks
located ahead of the access l inks used by the eNB 1 and the eNB 2,
respect ivel y, are the same and also, in the aggregat ion l ink, a backhaul
resource load increases and congest ion occurs.
20 [0014]
When a backhaul resource load of the access l ink used by the eNB 1
is high and a backhaul resource load of the access l ink used by the eNB 2 is
l ight , a load dist ribut ion funct ion works in each eNB. In other words, the
procedures 3 to 4 are executed. Thereby, the cel l where the radio
25 terminal is located is handovered from the cel l of the eNB 1 to the cel l of
the eNB 2. As a resul t , the backhaul resou rce loads in the access l inks
are dist ributed. However, in the aggregat ion l ink, the backhaul resource
load is unchanged and therefore, congest ion is not el iminated. Therefore,
i t is di fficul t to avoid a throughput decrease of the radio terminal in the
5
cel l of the eNB 2 of the handover dest inat ion. The reason is that a value
i n d i cat e d b y “S 1 TN L Lo a d In d i c at o r ” i n cl u d ed i n t h e RESOURCE
STATUS UPDATE message indicates a backhaul resource load of the
access l ink. In other words, load dist ribut ion consider ing load
informat ion of the aggregat ion l ink is not executed5 .
[0015]
An eNB can acqui re load informat ion of a l ink from a management
apparatus (NMS (Network Management System) ) that manages backhaul
resources between the eNB and a mobi le core network. However, in some
10 cases, the NMS does not manage al l l inks between the eNB and the mobi le
core network. For example, the NMS may manage only a backhaul of an
access l ink. In such a case, i t is di ff icul t for the eNB to know load
informat ion of a l ink having a highest load, i .e. a bot t leneck l ink between
the eNB and the mobi le core network. As a resul t , even when the eNB
15 can acquire load informat ion of a l ink from the NMS, i t may be di fficul t to
avoid backhaul congest ion and a throughput decrease of a radio t erminal .
[0016]
Accordingl y, the present invent ion is intended to provide a radio
base stat ion, a t raff ic load distr ibut ion method, and a storage medium
20 storing a t raffic load dist ribut ion program, that can more certainly avoid
backhaul congest ion and a throughput decrease of a radio terminal .
[Solut ion to Problem]
[0017]
A radio base stat ion, according to the present invent ion, comprises:
25 a determinat ion means for generat ing network load informat ion
indicat ing a t raffic load in a backhaul between an own stat ion and a core
network; and
an execut ion means for execut ing dist ribut ion of traff ic loads
among radio base stat ions on the basis of the network load informat ion
6
generated by the determinat ion means and network load informat ion
received f rom an adjacent radio base stat ion.
[0018]
A traffic load dist ribut ion method, according to the present
invent ion, comprises5 :
determining network load informat ion indicat ing a traff ic load in a
backhaul between an own stat ion and a core network; and
execut ing dist r ibut ion of t raffic loads among radio base stat ions on
the basis of the determined network load informat ion and network load
10 informat ion received f rom an adjacent radio base stat ion.
[0019]
A non-t ransi tory storage medium according to the present invent ion
stores a traffic load dist ribut ion program, that causes a computer to
execute:
15 processing for determining network load informat ion indicat ing a
traffic load in a backhaul between an own stat ion and a core network; and
processing for execut ing distr ibut i on of t raffic loads among radio
base stat ions on the basis of the determined network load informat ion and
network load informat ion received f rom an adjacent radio base stat ion.
20 [Advantageous Effects of Invent ion]
[0020]
According to the present invent ion, i t is possible to more certainly
avoid backhaul congest ion and a throughput decrease of a radio terminal .
[Brief Descript ion of Drawings]
25 [0021]
[Fig. 1] Fig. 1 is a block diagram i l lust rat ing an out l ine of a radio
communicat ion network including a radio base stat ion according to the
present invent ion.
[Fig. 2] Fig. 2 is a block diagram i l lustrat ing one example of a
7
configurat ion of the radio communicat ion network i l lustrated in Fig. 1.
[Fig. 3] Fig. 3 is an i l lustrat ive diagram i l lustrat ing how an eNB
handovers a radio terminal f rom a cel l where the radio terminal is located
to another cel l .
[Fig. 4] Fig. 4 is a block diagram i l lust rat ing a configurat ion of 5 a
first exemplary embodiment of the radio base stat ion according to the
present invent ion.
[Fig. 5] Fig. 5 is an i l lust rat ive diagram i l lustrat ing one example of
informat ion represent ing a determinat ion algori thm of S1 network load
10 informat ion.
[Fig. 6] Fig. 6 is an i l lust rat ive diagram i l lust rat ing a RESOURCE
STATUS UPDATE message in which a Packet Loss Rate and a Delay
Variat ion are designated.
[Fig. 7] Fig. 7 is an i l lust rat ive diagram i l lustrat ing one example of
15 informat ion represent ing a determinat ion algori thm cor responding to a
backhaul of an opt ical l ine.
[Fig. 8] Fig. 8 is an i l lust rat ive diagram i l lustrat ing one example of
informat ion represent ing a determinat ion algori thm cor responding to a
backhaul of a satel l i te l ine.
20 [Fig. 9] Fig. 9 is a block diagram i l lustrat ing a minimal
configurat ion of the radio base stat ion according to the pre sent invent ion.
[Fig. 10] Fig. 10 is an i l lust rat ive diagram i l lustrat ing one example
of a mobi le backhaul .
[Fig. 11] Fig. 11 is a sequence diagram i l lustrat ing resource status
25 report ing processing between eNBs.
[Fig. 12] Fig. 12 is an i l lustrat ive diagram i l lustrat ing a structure of
a RESOUCE STATUS REQUEST message.
[Fig. 13] Fig. 13 is an i l lustrat ive diagram i l lustrat ing a structure of
a RESOURCE STATUS UPDATE message.
8
[Descript ion of Embodiments]
[0022]
Fi rst Exemplary Embodiment
A first exemplary embodiment of the present invent ion wi l l be
described wi th reference to the drawings5 .
[0023]
Fig. 1 is a block diagram i l lust rat ing an out l ine of a radio
communicat ion network including a radio base stat ion according to the
present invent ion. As i l lust rated in Fig. 1, the radio base stat ion (eNBs
10 103 to 105) according to the present invent ion is connected to an EPC
(Evolved Packet Core) network (hereinaf ter, refer red to simply as an EPC)
100 that is a mobi le core network via a backhaul 200.
[0024]
Fig. 2 is a block diagram i l lust rat ing one example of a
15 configurat ion of the radio communicat ion network i l lust rated in Fig. 1.
In the example i l lustrated in Fig. 2, the eNBs 103 to 105 each are
connected to the EPC 100 via l inks 111 to 115 and relay apparatuse s 101 to
102. In other words, the l inks 111 to 115 are equivalent to the backhaul
200 i l lust rated in Fig. 1. The eNB 103 and the eNB 104 are connected to
20 the relay apparatus 101. The eNB 105 is connected to the relay apparatus
102. Further, the relay apparatuses 101 to 102 are connected to the EPC
100. The eNB 103 and the eNB 104, and the eNB 104 and the eNB 105
are connected via an X2 l ink, respect ively. It should be noted that in Fig.
2, two relay apparatuses and three eNBs are exempl i fied, but any number
25 of relay apparatuses and eNBs may be provided.
[0025]
Here, it is assumed that a radio terminal 106 is located in a cel l of
the eNB 104 (a cel l 108 i l lust rated in Fig. 2). The radio terminal 106 is
connected to the EPC 100 via the eNB 104 and the relay apparatus 101.
9
Further, a state of a backhaul resource load in the l ink 111 that connects
t h e E PC 1 0 0 a n d t h e r el a y ap p a r at u s 1 0 1 i s “Hi g h Lo a d . ” A s t at e o f a
backhaul resource load in the l ink 112 that connects the EPC 100 and the
relay apparatus 10 2 i s “Med i umLo a d . ” A s t at e o f a b a c k h au l r es o u r c e
load in the l ink 113 that connects the relay apparatus 101 and the eNB 105 3
i s “ LowLo a d . ” A s t at e o f a b a ck h au l r es o u r c e l o ad i n t h e l i n k 11 4 t h at
co n n e ct s t h e r el a y a p p a r a t u s 1 0 1 an d t h e eNB 1 0 4 i s “Hi g h Lo a d . ” A s t a t e
of a backhaul resource load in the l ink 115 that connects the relay
ap p a r a t u s 1 0 2 an d t h e eNB 1 0 5 i s “Me d i umLo ad . ”
10 [0026]
Fo r ex amp l e, “S 1 TNL Lo a d Indicator, ” i . e . a v al u e o f S 1 n e two r k
load informat ion received by the eNB 104 f rom the eNB 103 indicates the
backhaul resource load of the l ink 113. Therefore, the eNB 104 acquires
“ LowLo a d ” a s t h e v al u e o f S 1 n et wo r k l o ad i n f o rmat i o n o f t h e eNB 1 0 3 .
15 In the simi lar manner, a value of S1 network load informat ion received by
the eNB 103 f rom t h e eNB 1 0 4 i s “Hi g h Lo ad . ” Fu r t h er, a v al u e o f S 1
network load informat ion received by the eNB 104 f rom the eNB 105 is
“Med i umLo ad . ”
[0027]
20 Here, it is assumed that the eNB 103, the eNB 104, and the eNB 105
share respect ive pieces of load informat ion and the eNBs determine which
adjacent cell is designated as a handover dest inat ion of the radio terminal
106 on the basis of values indicated by the respect ive pieces of load
informat ion. Herein, the eNBs are assumed to share only S1 network load
25 informat ion. At that t ime, when a load of the eNB 104 increases to some
extent , the eNB 104 determines a cel l of the eNB 103 (a cel l 107 i l lust rated
in Fig. 2) as a handover dest inat ion since the value of S1 network load
i n f o rmat i o n o f t h e eNB 1 0 3 i s “ LowLo a d . ”
[0028]
10
Fig. 3 is an i l lust rat ive diagram i l lustrat ing how the eNBs 103 to
104 handover a radio terminal f rom a cel l where the radio terminal is
located (the cel l 108) to another cel l (the cel l 107). As i l lust rated in Fig.
3, in order to easi ly handover the radio terminal 106 f rom the cel l 108 to
the cel l 107, the eNB 103 and the eNB 104 cooperate to change a set t ing o5 f
a handover at t ribute value. In other words, the eNB 103 and the eNB 104
each change a set t ing of a handover at tr ibute value and move a handove r
boundary to cause the cel l 107 to become a handover dest inat ion. An
area of the cel l 107 prior to the change of the handover at t ribute value is
10 i l lust rated using a dashed l ine in Fig. 3. When the radio terminal 106 is
located in the cel l 107, a backhaul resource load of the l ink 114 is reduced
and a backhaul resource load of the l ink 113 is increased. Thereby, the
loads are distributed between the l ink 113 and the l ink 114. However, a
backhaul resource load of the l ink 111 which aggregates the l ink 113 and
15 t h e l i n k 11 4 i s o r i gi n al l y “Hi gh Lo ad . ” T h e r ef o r e, ev en wh en t h e l o a d s
are dist ributed between the l ink 113 and the l ink 114, the load of the l ink
111 i s n o t r ed u c e d a n d r emai n s “Hi g h Lo ad . ” T h e r e f o r e, ev en wh en t h e
cel l where the radio terminal 106 is located is handovered, i t may be
difficul t to avoid a throughput decrease of the radio terminal 106.
20 [0029]
As an o p t imi z at i o n met h o d o f MLB, t h e r e i s “E n h a n c e d Mo b i l i t y
Lo a d Bal an ci n g Op t imi z at i o n i n LT E ” p r es en t ed b y NS N (No k i a S o l u t i o n s
and Networks) at an internat ional symposium (2012 IEEE 23rd
Internat ional Symposium on Personal , Indoor and Mobi le Radio
25 Communicat ions -(PIMRC) ). In this opt imizat ion method, a cel l of a
handover dest inat ion is determined based on a f requency band ut i l izable
for each adjacent radio base stat ion. Here, the frequency band ut i l izable
for each adjacent radio base stat ion is def ined by a di fference between al l
of the transport capaci t ies al located to radio base stat ions and a GBR
11
(Guaranteed Bi t Rate) sum of act ive bearer s. The GBR sum of act ive
bearers is a sum of GBRs of the act ive bearers including a communicat ion
overhead based on S1 Inter face protocol .
[0030]
The opt imizat ion method uses a transport capaci ty considering onl5 y
a backhaul resource load of a l ink, i .e. an access l ink between a radio base
stat ion and a fi rst -hop relay apparatus f rom the radio base stat ion.
Therefore, the opt imizat ion method does not consider backhaul resource
loads of an aggregat ion l ink located ahead of the access l ink. A case in
10 which a backhaul resource load of the aggregat ion l ink located ahead of the
access l ink is considered and a case in which the above mat ter is not
considered are different in a frequency band defined by a di fference
between a transport capaci ty and a GBR sum of act ive bearers. As a
resul t , even when on the basis of the opt imizat ion method, MLB is
15 executed between radio base stat ions, i t is di fficul t to avoid aggregat ion
l ink congest ion and a throughput decrease of a radio terminal .
[0031]
Accordingly, the radio base stat ion (the eNBs 103 to 105) according
to the present invent ion executes MLB consider ing a backhaul resource
20 load in an aggregat ion l ink.
[0032]
Fig. 4 is a block diagram i l lust rat ing a configurat ion of the fi rst
exemplary embodiment of the radio b ase stat ion according to the present
invent ion. As i l lustrated in Fig. 4, each eNB (the eNBs 103 to 105)
25 includes a communicat ion uni t 11, an est imat ion uni t 12, a storage uni t 13,
a determinat ion uni t 14, and an execut ion uni t 15.
[0033]
The communicat ion uni t 11 executes t ransmission/ recept ion of a
packet .
12
[0034]
The est imat ion uni t 12 est imates a Packet Loss Rate and a Delay
Variat ion in accordance wi th IP Per formance Met rics. Here, the Packet
Loss Rate refers to a loss rate of a packet t ransmi t ted t o an EPC by the
communicat ion uni t 11. The Delay Var iat ion refers to a magni tude of 5 a
Delay Variat ion of the packet t ransmi t ted to the EPC by the communicat ion
uni t 11. It should be noted that the est imat ion uni t 12 may est imate those
other than the Packet Loss Rate and the Delay Variat ion.
[0035]
10 The f ramework of IP Performance Met r ics is described in RFC
(Request for comments) 2330. IP Per formance Met rics are rules for a
technique in which in IP Layer, a packet t ransmission side est imates a
Packet Loss Rate and a Delay Variat ion of a packet transmi t ted by the own
side and evaluates rel iabi l i ty and per formance of a network. It should be
15 noted that as an est imat ion method for a Packet Loss Rate, for example, a
method described in RFC 2680 is used. Furt her, as an est imat ion method
for a Delay Variat ion, for example, a method described in RFC 3393 is
used.
[0036]
20 The storage uni t 13 stores informat ion represent ing a determinat ion
algori thm of S1 network load informat ion. Each value of the S1 network
load informat ion is determined based on est imat ion resul ts of a Packet
Loss Rate and a Delay Variat ion. Specifical l y, each value of the S1
network load informat ion is determined, for example, as any one of
25 “ LowLo a d , ” “Med i umLo ad , ” “Hi gh Lo ad , ” an d “Overload. ”
[0037]
Fig. 5 is an i l lust rat ive diagram i l lustrat ing one example of
informat ion represent ing a determinat ion algori thm of S1 network load
informat ion. As i l lust rated in Fig. 5, in the present exemplary
13
embodiment , the storage uni t 13 stores a table ind icat ing associat ion of a
Packet Loss Rate and a Delay Variat ion wi th each value of S1 network load
informat ion as informat ion represent ing a determinat ion algori thm of S1
network load informat ion. In the example i l lust rated in Fig. 5, a Packet
Loss Rate is classi fied into three stages, i .e. smal ler than 0.01, equal to o5 r
greater than 0.01 and smal ler than 0.05, and equal to or greater than 0.05.
Further, a Delay Variat ion is classi fied into three stages, i .e. smal ler than 1
msec, equal to or greater than 1 msec and smal ler than 5 msec, and equal to
or greater than 5 msec. Here, each value of S1 network load informat ion
10 i l lust rated in Fig. 5 indicates a backhaul resource load f rom an eNB to an
EPC, i .e. a t raffic load in the backhaul 200 i l lust rated in Fig . 1.
[0038]
It should be noted that values of a Packet Loss Rate and a Delay
Variat ion corresponding to each value of S1 network load informat ion
15 i l lust rated in Fig. 5 may be determined on the basis of measurement resul ts
of the Packet Loss Rate and the Delay Variat ion previously measured, for
example, in accordance wi th a state of a backhaul resource load f rom an
eNB to an EPC. Further, values of a Packet Loss Rate and a Delay
Variat ion cor responding to each value of S1 network load informat ion may
20 be changed by an operator in accordance wi th a configurat ion of a
communicat ion system and the l ike.
[0039]
The determinat ion uni t 14 determines S1 network load informat ion.
Specif ical l y, the determinat ion uni t 14 determines a backhaul resource load
25 from i ts own stat ion to the EPC 100 on the basis of est imat ion resul ts of a
Packet Loss Rate and a Delay Variat ion in the est imat ion uni t 12 based on
informat ion represent ing the determinat ion algori thm i l lust rated in Fig. 5.
Then, the determinat ion uni t 14 sets t he determinat ion resul t as S1 network
load informat ion of a RESOURCE STATUS UPDATE message to be
14
transmi t ted to an adjacent eNB.
[0040]
The execut ion uni t 15 t ransmi ts, to the adjacent eNB, the
RESOURCE STATUS UPDATE message including the S1 network load
informat ion set wi th the determinat ion resul t by the determinat ion uni t 15 4
via the communicat ion uni t 11. Further, the execut ion uni t 15 acqui res,
from the adjacent eNB, a RESOURCE STATUS UPDATE message
including S1 network load informat ion via the commun icat ion uni t 11.
[0041]
10 The execut ion uni t 15 executes MLB on the basis of the S1 network
load informat ion set wi th the determinat ion resul t by the determinat ion
uni t 14 and the S1 network load informat ion received from the adjacent
eNB.
[0042]
15 The communicat ion uni t 11, the est imat ion uni t 12, the
determinat ion uni t 14, and the execut ion uni t 15 are real ized, for example,
using a CPU (Central Processing Uni t) of a computer operat ing in
accordance wi th a t raffic load dist ribut ion program. The traffic loa d
distr ibut ion program is stored on, for example, a storage apparatus (not
20 i l lust rated) of the computer. The CPU reads the program and operates as
the communicat ion uni t 11, the est imat ion uni t 12, the determinat ion uni t
14, and the execut ion uni t 15 in a ccordance wi th the program. Further,
the communicat ion uni t 11, the est imat ion uni t 12, the determinat ion uni t
14, and the execut ion uni t 15 may be real ized using separate pieces of
25 hardware, respect ively.
[0043]
Further, the storage uni t 13 is real ized using a storage apparatus
such as a RAM (Random Access Memory) of a computer, or the l ike.
[0044]
15
Next , operat ions of respect ive uni ts in the present exemplary
embodiment wi l l be described.
[0045]
Herein, an operat ion of the eNB 103 represent ing the eNBs 103 to
105 i l lust rated in Fig. 1 wi l l be described5 .
[0046]
The communicat ion uni t 11 of the eNB 103 t ransmi ts a packet to the
EPC 100. The EPC 100 reports, to the eNB 10 3, a recept ion status of the
packet t ransmi t ted f rom the eNB 103.
10 [0047]
The est imat ion uni t 12 est imates a Packet Loss Rate and a Delay
Variat ion on the basis of the recept ion status of the packet reported f rom
the EPC 100 via the communicat ion uni t 11.
[0048]
15 The determinat ion uni t 14 determines a value to be set as S1
network load informat ion on the basis of the est imat ion resul ts of the
Packet Loss Rate and the Delay Variat ion in the est imat ion uni t 12. At
that t ime, the determinat ion uni t 14 determines the value to be set as S1
network load informat ion based on informat ion represent ing the
20 determinat ion algori thm stored on the storage uni t 13 as described above.
[0049]
When, for example, the Packet Loss Rate is 0.03 and the Delay
Variat ion is 3 msec, the determinat ion uni t 14 determines a value to be set
as S1 network load informat i o n a s “Med i umLo a d ” u s i n g i n f o rmat i o n
25 represent ing the determinat ion algori thm i l lust rated in Fig. 5. This
determinat ion resul t indicates that a backhaul resource load from the eNB
1 0 3 t o t h e E PC 1 0 0 i s “Me d i um Lo ad . ”
[0050]
The execut ion uni t 15 t ransmi t s a RESOURCE STATUS UPDATE
16
message including the S1 network load informat ion set wi th the
determinat ion resul t of the determinat ion uni t 14 to an adjacent eNB, for
example, the eNB 104 i l lustrated in Fig. 1 via the communicat ion uni t 11.
[0051]
When the eNBs 104 and 105 i l lust rated in Fig. 1 each t ransmi t 5 a
RESOURCE STATUS UPDATE message using the same method as in the
eNB 103, the eNBs can acquire informat ion indicat ing a backhaul resource
load of an adjacent eNB. In other words, the eNBs can share piece s of
informat ion indicat ing backhaul resource loads f rom respect ive eNBs to an
10 EPC. Therefore, the execut ion uni t 15 of each eNB can execute MLB
consider ing a backhaul resource load of an aggregat ion l ink. In other
words, each eNB can designate a cel l of an adjacent eNB having a less load
wi th respect to a radio terminal as a handover dest inat ion.
[0052]
15 As described above, in the present exemplary embodiment , an eNB
est imates a Packet Loss Rate and a Delay Variat ion of a packet transmi t ted
to an EPC and determines S1 network load informat ion indicat ing a t raffic
load from the eNB to the EPC on the basis of the est imat ion resul ts.
Thereby, even when a backhaul between an eNB and a mobi le core network
20 includes a plural i ty of l inks, S1 network load informa t ion consider ing the
presence of al l of the l inks can be determined.
[0053]
Further, in the present exemplary embodiment , the determined S1
network load informat ion is reported to an adjacent eNB. Thereby, eNBs
25 can share pieces of informat ion indicat ing backhaul resource loads from
the respect ive eNBs to an EPC. Therefore, each eNB can execute MLB
consider ing not only backhaul resources of an access l ink but also the
ent i re congest ion status of backhaul resources including a plural i ty of l inks.
Therefore, i t is possible to cause Handover between eNBs during MLB
17
execut ion to succeed more certainl y. Therefore, congest ion between an
eNB and an EPC, for example, aggregat ion l ink congest ion can be avoided.
Further, a throughput decrease of a radio terminal can be avoided more
certainl y.
[00545 ]
The present invent ion is appl icable to a communicat ion system
including a plural i ty of radio base stat ions and a cont rol apparatus that
manages backhaul resources.
[0055]
10 It should be noted that in the present exemplary embodiment , a case
in which a communicat ion uni t reports S1 network load informat ion to an
adjacent eNB has been described, but the communicat ion uni t may be
configured to t ransmi t values of a Packet Loss Rate and a Delay Variat ion
est imated by an est imat ion uni t , together wi th S1 network load informat ion.
15 For example, as addi t ive IEs ( Informat ion Elements) of a RESOURCE
STATUS UPDATE mes s a g e ac r o s s an X2 l i n k , a “P a ck et Lo s s Rat e” an d a
“Del a y Va r i a t i o n ” ma y b e d es i g n at ed . Then, the communicat ion uni t may
transmi t a RESOURCE STATUS UPDATE message thereof . Fig. 6 is an
i l lust rat ive diagram i l lust rat ing a RESOURCE STATUS UPDATE message
20 in which a Packet Loss Rate and a Delay Variat ion are designated.
According to such a conf igurat ion, when, for exampl e, a RESOURCE
STATUS UPDATE message is transmi t ted f rom the eNB 103 to the eNB 104,
the eNB 104 can acquire values of a Packet Loss Rate and a Delay
Variat ion of the eNB 103.
25 [0056]
Further, control apparatuses (SON(Sel f Organizing
Network)/EMS(Element Management System)/HeNB-GW(Home
eNB-Gateway) ) that manage eNBs may col lect values of a Packet Loss
Rate and a Delay Variat ion t ransmi t ted f rom an eNB. Then, the cont rol
18
apparatuses may determine a backhaul resource load via associat ion wi th
an index of any o n e o f f o u r s t a g e s ( “ LowLo a d , ” “Med i umLo ad , ”
“Hi g h Lo a d , ” an d “Ov e r l o ad ” ) i n t h e simi lar manner as for S1 network load
informat ion, on the basis of the values of the Packet Loss Rate and the
Delay Variat ion between the eNB and an EPC5 .
[0057]
Further, i t is possible that the est imat ion uni t 12 est imates a Packet
Loss Rate and a Delay Variat ion f rom a traff ic from an eNB to SeGW
(Securi ty Gateway) , a swi tch, or a router, and the determinat ion uni t
10 determines S1 network load informat ion on the basis of the est imat ion
resul ts.
[0058]
Further, i t is possible that the est imat ion uni t 12 est imates a Packet
Loss Rate and a Delay Variat ion between an eNB and an EPC using Ping
15 (Packet INternet Groper) or ECN (Expl ici t Congest ion Not i ficat ion)
described in RFC 3168.
[0059]
Second Exemplary Embodiment
A second exemplary embodiment of the present invent ion wi l l be
20 described wi th reference to the drawings.
[0060]
A configurat ion of a radio base stat ion in the second exemplary
embodiment is the same as in the f irst exemp lary embodiment .
[0061]
25 However, a storage uni t 13 of the present exemplary embodiment
stores informat ion represent ing a determinat ion algor i thm for each type of
a l ink of a backhaul between an eNB and an EPC. In the present
exemplary embodiment , the storage uni t 13 stores informat ion represent ing
a determinat ion algori thm cor responding to a backhaul of an opt ical l ine
19
and informat ion represent ing a determinat ion algor i thm cor responding to a
backhaul of a satel l i te l ine. Fig. 7 is an i l lust rat ive diagram i l lustrat ing
one example of informat ion represent ing a determinat ion algori thm
corresponding to a backhaul of an opt ical l ine. In the example i l lust rated
in Fig. 7, a Packet Loss Rate is classi fied into three stages, i .e. smal le5 r
than 0.001, equal to or greater than 0.001 and smal ler than 0.005, and equal
to or greater than 0.005. Further, a Delay Variat ion is classi fied into
three stages, i .e. smal ler than 0.01 msec, equal to or greater than 0.01 msec
and smal ler than 0.05 msec, and equal to or greater than 0.05 msec. Fig.
10 8 is an i l lust rat ive diagram i l lustrat ing one example of informat ion
represent ing a determinat ion algori thm corresponding to a backhaul of a
satel l i te l ine. In the example i l lustrated in Fig. 8, a Packet Loss Rate is
classi fied into three stages, i .e. smal ler than 0.05, equal to or greater than
0.05 and smal ler than 0.1, and equal to or greater than 0.1. Further, a
15 Delay Variat ion is classi fied into three stages, i .e. smal ler than 10 msec,
equal to or greater than 10 msec and smal ler than 50 msec, and equal to or
greater than 50 msec.
[0062]
Further, a determinat ion uni t 14 of the present exemplary
20 embodiment swi tches a determinat ion algori thm of S1 network load
informat ion in accordance wi th a type of a l ink of a backhaul . When, for
example, a l ink of a backhaul is an opt ical l ine, S1 network load
informat ion is determined on the basis of the informat ion i l lustrated in Fig.
7. Further, when, for example, a l ink of a backhaul is a satel l i te l ine, S1
25 network load informat ion is determined on the basis of the informat ion
i l lust rated in Fig. 8.
[0063]
In this manner, in the present exemplary embodiment , the eNB 103
est imates a Packet Loss Rate and a Delay Variat ion of a packet transmi t ted
20
to the EPC 100 in accordance wi th a type of a l ink of a backhaul and
determines S1 network load informat ion on the basis of the est imat ion
resul ts.
[0064]
It should be noted that when i t is possible for a communicat ion uni 5 t
11 to acqui re informat ion indicat ing a type of a l ink of a backhaul from a
relay apparatus or the l ike, the communicat ion uni t 11 may determine a
type of a l ink of a backhaul on the basis of the informat ion and report the
determinat ion resul t to the determinat ion uni t 14. Further, an operator or
10 the l ike may specify in advance a type of a l ink of a backhaul for the
determinat ion uni t 14 via an operat ion uni t (not i l lust rated) of an eNB.
[0065]
In the present exemplary embodiment , a determinat ion algori thm of
S1 network load informat ion is swi tched in accordance wi th a type of a
15 backhaul l ine, and therefore the same advantageous effect as in the first
exemplary embodiment can be obtained and a value of S1 network load
informat ion cor responding to a type of an in -use backhaul l ine can be
determined. In other words, a value of S1 network load informat ion can
be determined on the basis of a packet loss and a delay variat ion l ikely to
20 actual ly occur in an in-use backhaul l ine.
[0066]
It should be noted that also in the present exemplary embodiment ,
control apparatuses (SON/EMS/HeNB-GW) that manage eNBs may
est imate a Packet Loss Rate and a Delay Variat ion f rom a traffic f rom an
25 eNB to SeGW, a swi tch, or a router and determine a value of S1 network
load informat ion on the basis of the est imat ion resul ts.
[0067]
Next , an out l ine of the pr esent invent ion wi l l be described. Fig. 9
is a block diagram i l lust rat ing a minimal conf igurat ion of the radio base
21
stat ion according to the present invent ion. The radio base stat ion
according to the present invent ion includes: a determinat ion uni t 14 th at
determines network load informat ion indicat ing a traffic load in a backhaul
between an own stat ion and a core network; and an execut ion uni t 15 that
executes distribut ion of traff ic loads among radio base stat ions on the basi5 s
of the network load informat ion determined by the determinat ion uni t 14
and network load informat ion received f rom an adjacent radio base stat ion.
[0068]
According to such a configurat ion, even when a backhaul between
10 an eNB and a mobi le core network includes a plural i ty of l inks, a backhaul
resource load considering the presence of al l of the l inks can be determined.
Thereby, MLB can be executed by considering not only backhaul resources
in an access l ink but also the ent i re congest ion status of backhaul resources
including a plural i ty of l inks.
15 [0069]
Further, the radio base stat ion according to the present invent ion
may include an est imat ion uni t 12 (see Fig. 4) that est imates a loss rate and
a Delay Variat ion of a packet t ransmi t ted from an own stat ion to a core
network. Then, the determinat ion uni t 14 may determine a traffic load in
20 a backhaul between the own stat ion and the core network on the basis of
the est imat ion resul ts of the est imat ion uni t 12 and designate the
determinat ion resul t as network load informat ion. Accord ing to such a
configurat ion, when a resul t obtained by analyzing a packet travel l ing
between an own stat ion and a core network is used to determine a t raffic
25 load, a t raffic load in a backhaul between the own stat ion and the core
network can be determined more accurately.
[0070]
Further, the radio base stat ion according to the present invent ion
may include a storage uni t 13 (see Fig. 4) that stores informat ion
22
represent ing a determinat ion algori thm for determining, on the basis of a
loss rate and a Delay Variat ion of a packet transmi t ted f rom an own stat ion
to a core network, a traffic load in a backhaul between the own stat ion and
the core network. Then, the determinat ion uni t 14 may determine a
traffic load in the backhaul between the own stat ion and the core networ5 k
on the basis of est imat ion resul ts of the est imat ion uni t 12 based on the
determinat ion algori thm. According to such a configurat ion, on the basis
of a loss rate and a Delay Variat ion of a packet transmi t ted f rom an own
stat ion to a core network, a t raffic load, i .e. S1 network load informat ion in
10 a backhaul between the own stat ion and the core network can be certainly
determined. Fur ther, when in accordance wi th a configurat ion of a
communicat ion system or the l ike, an operator changes a de terminat ion
algori thm to be used among a plural i ty of types of determinat ion
algori thms stored on the storage uni t 13, the determinat ion uni t 14 can
15 determine a t raffic load more accuratel y.
[0071]
Further, the execut ion uni t 15 may transmi t network load
informat ion determined by the determinat ion uni t 14 to an adjacent radio
base stat ion. According to such a conf igurat ion, eNBs can share pieces
20 of informat ion indicat ing backhaul resource loads from the respect ive
eNBs to an EPC. Therefore, each eNB can execute MLB by considering
not only backhaul resources of an access l ink but also the ent i re congest ion
status of backhaul resources including a plural i ty of l inks. Ther efore, i t
is possible to cause Handover between eNBs during MLB execut ion to
25 succeed more certainly. Therefore, congest ion between an eNB and an
EPC can be avoided. Further, a throughput decrease of a radio terminal
can be avoided more certainl y.
[0072]
Further, the execut ion uni t 15 may t ransmi t a loss rate and a Delay
23
Variat ion of a packet est imated by the est imat ion uni t 12 to an adjacent
radio base stat ion, together wi th network load informat ion. According to
such a conf igurat ion, a radio base stat ion can determine, for example, on
the basis of values of a loss rate and a Delay Variat ion of a packet received
from another radio base stat ion, a backhaul resource load from the anothe5 r
radio base stat ion to an EPC based on a determinat ion algori thm stored on
the own stat ion.
[0073]
Further, i t is possible that the storage uni t 13 stores informat ion
10 represent ing a determinat ion algori thm for each type of a backhaul l ine and
the determinat ion uni t 14 determines network load informat ion based on a
determinat ion algori thm corresponding to a type of a backhaul l ine used by
an own stat ion. According to such a configurat ion, MLB corresponding
to a type of a backhaul l ine used by an own stat ion can be executed.
15 Thereby, congest ion between an eNB and an EPC can be avoided more
certainl y. Further, a throughput decrease of a radio terminal can be
avoided more cer tainly.
[0074]
Further, the execut ion uni t 15 may execute Handover on the basis of
20 network load informat ion determined by the determinat ion uni t 14 and
network load informat ion received from an adjacent radio base stat ion and
cause a radio terminal located in a cel l of an own stat ion to be located in a
cel l of an adjacent radio base stat ion where a t raffic load indicated by the
received network load informat ion is smal l er. According to such a
25 configurat ion, a radio terminal can be located in a cel l of an adjacent eNB
where a traffic load in a backhaul between the eNB and a core network is
smal ler. Thereby, backhaul congest ion and a throughput decrease of a
radio terminal can be avoided more certainly.
[0075]
24
The whole or part of the exemplary embodiments disclosed above
can be described as , but not l imi ted to, the fol lowing supplementary notes.
[0076]
(Supplementary Note 1) A radio base stat ion compris ing: a determinat ion
means for determining network load informat ion indicat ing a t raffic load i5 n
a backhaul between an own stat ion and a core network; and an execut ion
means for execut ing distr ibut ion of traffic loads among radio base stat ions
on the basis of the network load informat ion determined by the
determinat ion means and network load informat ion received f rom an
10 adjacent radio base stat ion.
[0077]
(Supplementary Note 2) The radio base stat ion according to Supplementary
Note 1, further comprising: an est imat ion means for est imat ing a loss rate
and a Delay Variat ion of a packet transmi t ted f rom an own stat ion to a core
15 network, wherein the determinat ion means determines, on the basis of the
est imat ion resul ts of the est imat ion means, a traffic load in a backhaul
between the own stat ion and the core network and designates the
determinat ion resul t as network load informat ion.
[0078]
20 (Supplementary Note 3) The radio base stat ion according to Supplementary
Note 2, wherein the execut ion means transmi ts the loss rate and the Delay
Variat ion of the packet est imated by the est imat ion means to an ad jacent
radio base stat ion, together wi th the network load informat ion.
[0079]
25 (Supplementary Note 4) The radio base stat ion according to Supplementary
Note 2 or Supplementary Note 3, further comprising: a storage means for
storing informat ion represent ing a determinat ion algor i thm for determining,
on the basis of a loss rate and a Delay Variat ion of a packet transmi t ted
from an own stat ion to a core network, a t raffic load in a backhaul between
25
the own stat ion and the core network, wherein the determinat ion means
determines, based on the determinat ion algori thm, a t raffic load in a
backhaul between an own stat ion and a core network on the basis of
est imat ion resul ts of the est imat ion means.
[00805 ]
(Supplementary Note 5) The radio base stat ion according to Supplementary
Note 4, wherein the storage means stores informat ion represent ing a
determinat ion algor i thm for each type of a backhaul l ine, and the
determinat ion means determines network load informat ion using a
10 determinat ion algori thm corresponding to a type of a backhaul l ine used by
an own stat ion.
[0081]
(Supplementary Note 6) The radio base stat ion according to any one of
Supplementary Note 1 to Supplementary Note 5, wherein the execut ion
15 means transmi ts the network load informat ion determined by the
determinat ion means to an adjacent radio base stat ion.
[0082]
(Supplementary Note 7) The radio base stat ion according to any one of
Supplementary Note 1 to Supplementary Note 6, wherein the execut ion
20 means executes Handover on the basis of the network load in format ion
determined by the determinat ion means and network load informat ion
received from the adjacent radio base stat ion and causes a radio terminal
located in a cel l of an own stat ion to be located in a cel l of an adjacent
radio base stat ion where a t ra ffic load indicated by the received network
25 load informat ion is smal ler.
[0083]
(Supplementary Note 8) The radio base stat ion according to any one of
Supplementary Note 2 to Supplementary Note 7, wherein the determinat ion
means determines a t raffic load in a backhaul between an own stat ion and a
26
core network via associat ion wi th an i n d ex o f “S 1 TN L Lo a d ” in a
RESOURCE STATUS UPDATE message defined by technical
speci ficat ions (TS 36.423 Version 11.5.0).
[0084]
(Supplementary Note 9) The radio base stat ion ac cording to any one o5 f
Supplementary Note 2 to Supplementary Note 8, wherein the est imat ion
means est imates a loss rate and a Delay Variat ion of a packet transmi t ted
from an own stat ion to SeGW, a swi tch, or a router.
[0085]
10 (Supplementary Note 10) The radi o base stat ion according to any one of
Supplementary Note 2 to Supplementary Note 9, wherein the est imat ion
means est imates a Packet Loss Rate and a Delay Var iat ion between a radio
base stat ion and an EPC using Ping or ECN.
[0086]
15 Whi le the invent ion has been part icularly shown and described wi th
reference to exemplary embodiments thereof, the invent ion is not l imi ted
to these embodiments. It wi l l be understood by those of ordinary ski l l in
the art that various changes in form and detai ls may be made ther ein
wi thout depar t ing from the spi ri t and scope of the present invent ion as
20 defined by the claims.
[0087]
This appl icat ion is based upon and claims the benefi t of pr iori ty
from Japanese patent appl icat ion No. 2013-222924, fi led on October 28,
2013, the disclosure of which is incorporated herein in i ts ent i rety by
25 reference.
[Reference signs List]
[0088]
11 Communicat ion uni t
12 Est imat ion uni t
27
13 Storage uni t
14 Determinat ion uni t
15 Execut ion uni t
100 EPC
101, 102 Relay apparatu5 s
103, 104, 105 eNB
106 Radio terminal
107, 108, 109 Cel l
111, 112, 113, 114, 115 Link
10 200 Backhaul
28

[Document Name] CLAIMS
[Claim 1]
A radio base stat ion comprising:
a determinat ion means for determining network load informat ion
indicat ing a t raffic load in a backhaul between an own stat ion and a cor5 e
network; and
an execut ion means for execut ing dist ribut ion of traff ic loads
among radio base stat ions on the basis of the network load informat ion
determined by the determinat ion means and network load informat ion
10 received f rom an adjacent radio base stat ion.
[Claim 2]
The radio base stat ion according to Claim 1, further comprising
an est imat ion means for est imat ing a loss rate and a Delay Variat ion
of a packet transmi t ted f rom an own stat ion to a core netwo rk, wherein
15 the determinat ion means determines, on the basis of the est imat ion
resul ts of the est imat ion means, a traffic load in a backhaul between the
own stat ion and the core network and designates the determinat ion resul t
as network load informat ion.
[Claim 3]
20 The radio base stat ion according to Claim 2, wherein
the execut ion means transmi ts the loss rate and the Delay Variat ion
of the packet est imated by the est imat ion means to an adjacent radio base
stat ion, together wi th the network load informat i on.
[Claim 4]
25 The radio base stat ion according to Claim 2 or Claim 3, further
comprising
a storage means for storing informat ion represent ing a
determinat ion algori thm for determining, on the basis of a loss rate and a
Delay Var iat ion of a packet t ransmi t ted from an own stat ion to a core
29
network, a t raffic load in a backhaul between the own stat ion and the core
network, wherein
the determinat ion means determines, based on the determinat ion
algori thm, a t raffic load in a backhaul between an own stat ion an d a core
network on the basis of est imat ion resul ts of the est imat ion means5 .
[Claim 5]
The radio base stat ion according to Claim 4, wherein
the storage means stores informat ion represent ing a determinat ion
algori thm for each type of a backhaul l ine, and
10 the determinat ion means determines network load informat ion using
a determinat ion algori thm cor responding to a type of a backhaul l ine used
by an own stat ion.
[Claim 6]
The radio base stat ion according to any one of Claim 1 to Claim 5,
15 wherein
the execut ion means t ransmi ts the network load informat ion
determined by the determinat ion means to an adjacent radio base stat ion.
[Claim 7]
The radio base stat ion according to any one of Claim 1 to Claim 6,
20 wherein
the execut ion means executes Handover on the basis of the network
load informat ion determined by the determinat ion means and network load
informat ion received f rom the adjacent radio base stat ion and causes a
radio terminal located in a cel l of an own stat i on to be located in a cel l of
25 an adjacent radio base stat ion where a t raffic load indicated by the received
network load informat ion is smal l er.
[Claim 8]
A t raffic load dist ribut ion method comprising:
determining network load informat ion indicat ing a traff ic load in a
30
backhaul between an own stat ion and a core network; and
execut ing dist ribut ion of t raffic loads among radio base stat ions on
the basis of the determined network load informat ion and network load
informat ion received f rom an adjacent radio base stat ion.
[Claim 95 ]
A non-t ransi tory storage medium storing a t raffic load dist ribut ion
program that causes a computer to execute:
processing for determining network load informat ion indicat ing a
traffic load in a backhaul between an own stat ion and a core network; and
10 processing for execut ing distr ibut ion of t raffic loads among radio
base stat ions on the basis of the determined network load informat ion and
network load informat ion received f rom an adjacent radio base stat ion.