1. A communication system comprising: a terminal; 5 a first base station to which the terminal is connected before movement; a second base station to which the terminal is connected after movement; and a gateway device that connects the first base station and the second base station to an upper net work so that they are able to communicate with each other, wherein the first base station transmits, to the second base station , a first signal to request the second base station to start a handover, the first signal including transport information which has been used for data downlink data transmission by the gateway device and the first base station communicating with the gateway device during a handover of the terminal , the second base station receives the first signal and transmits, to the gateway device, a second signal to request the gateway device to update the transport information , the second signal including the transport information, and the gateway de vice receives the second signal and hands over the transport information of the first base station to a communication with the second base station .

2. The communication system according to Claim 1, wherein the second base stat ion transmits, to the gateway device, the second signal including configuration information to disable setting of the transport information . 30

3. The communication system according to Claim 1 or 2, wherein t he first base station transmits the first signal to the second base station via the gateway device.

4. A base station comprising: transmission means for transmitting , when a handover occurs during communication with a terminal , a first signal to a second base station , the first signal requesting the second base station to start the handover and including transport information which has been used for downlink data transmission by the base station and the gateway device.

5. A base station comprising: reception means for receiving , when a handover of a terminal communicating with a first base station occurs, a first signal for requesting to start the handover, the first signal including transport information which has been used for downlink data transmission by the first base station and a gateway device ; and transmission means for transmitting, to the gateway device , a second signal to request the gateway device to update the transport information , the second signal including the transport information.

6. The base station according to Claim 5, wherein the transmission means transmits, to the gateway device , a second signal 20 including configuration information to disable setting of the transport information .

7. A gateway device comprising: reception means for receiving , when a handover of a terminal communicating with a first base station occurs, a second signal for requesting to update transport information, the second signal being transmitted from a second base station and including the transport information which has been used for downlink data trans mission by th e first base station and the gateway device; and handover means for handing over the transport information to a communication with the second base s tati on.

8. The gateway device according to Claim 7 , wherein the reception means receives the second signal including configuration information to disable setting of the transport info rmation , the second signal being transmitted from the second base station .

9. A method for controlling a base station, comprising: receiving, when a handover of a terminal communication with a first base station occurs, a first signal for requesting to start the handover , the first signal including transport information which has been used for downlink data transmission by the first base station and a gateway device; and transmitting, to the gateway device, a second signal to request the gate way device to update the transport information , the second signal including the transport information .

10. A method for controlling a gateway device , comprising: receiving, when a handover of a terminal communicating with a first base station occurs, a second signal for requesting to update transport information, the second signal being transmitted from a second base station and including the transport information which has been used for downlink data transmission by the first base station and 20 the gateway device; and handi ng over the trans port information to a communication with the second base station .

DESCRIPTION
COMMUNICATION SYSTEM, BASE STATION, GATEWAY DEVICE, BASE STATION CONTROL METHOD, AND GATEWAY DEVICE
CONTROL METHOD 5
Technical Field
[ 0001]
Th e p r esent in ven t ion re lates to a commu nicati on s yst e m, a b ase
s t at ion , a ga t ewa y devi ce, a ba s e st atio n c ont r ol me th od , and a gat ew a y
10 devi ce cont rol metho d , a nd more p art i cular l y, t o a h and over of a b as e
st at ion .
Background Art
[ 0002]
15 A small base station (femtocell) which is called an HNB (Home
Node B : home base st atio n ) a nd is a ss umed to be u s ed , for ex am ple , at home has been st udi ed . A fem t ocell i s, for ex ampl e , a mi cro/l ow-power i ndo or b as e s tatio n whi ch co ve rs an a r ea wi thin a radiu s o f s everal met ers to se veral t ens o f met ers and is use d fo r m obil e
20 communication services. A radio wave from a macrocell may not reach
so m e loc ati on s su ch a s ind oors . The f emto cell is an in doo r b as e st at ion fo r constru cting a st able radi o commu nic ati on env ironm ent for an area in which the communication environment is poor and radio wa ves fro m ma croc el l st atio ns do n ot re ac h. In t he near future , it i s
25 expect ed th at a l arge num ber of f emt ocel ls (H N Bs) wi ll be su bordi nate
t o a macroc ell . [ 0003]
S in ce t he femto ce ll ( HN B) co ve rs a sma ll a r ea , w hen a mo bil e s t at ion i s mo vin g, h and ov er oc cu r s mo r e f r equentl y in t he femt oc el l
30 t han in t he m ac r oc el l . Ac cordin gl y, a s mooth h an dov er cont r ol for th e
f em tocell (H NB) i s impo rtan t. 3GP P ( Th ird G ene r ati on P artn ers hip P r oj ect ) p resents c omm uni ca tion us ing a lo gi ca l i nterf ac e c al led Iu r h f or a han dov er be t ween H NB s . No n Paten t Li t erat ure 3 rel ati ng t o th e

3 3GPP defines Iurh Interface for performing communication by RNSAP (Radio Network Subsystem Application Part) Signallin g between HNBs. [ 0004]
Non P at en t Li te rat u re 1 t o 9 disc lo s e f emto cell s (H N Bs) th at
5 pe rform c ommuni cat ion vi a Iurh In te rface. P at ent Li terat u re 1
pres ent s a dat a tra nsmi ssio n m eth od fo r redu cin g da ta trans miss i on paths for f em tocel ls.
Ci ta tion List
10 Patent Literatu re
[ 0005]
[ P at en t Li te rat u re 1] P ubl ish ed J apa ne s e T r ansl atio n of PCT In t e r natio n al P ubl ic ati on fo r P ate nt Ap plicat ion , No . 201 2 -52 171 0
Non Patent Literature
15 [0006]
[ Non P at ent Li te ra t u re 1] 3 GPP TS 2 5 .4 1 3 V e r .1 1 .2.0 [ Non P at ent Li te ra t u re 2] 3 GPP TS 2 5 .4 2 3 V e r .1 1 .4.0 [ Non P at ent Li te ra t u re 3] 3 GPP TS 2 5 .4 6 7 V e r .1 1 .1.0 [ Non P at ent Li te ra t u re 4] 3 GPP TS 2 5 .4 6 8 V e r .1 1 .1.0
20 [ Non P at ent Li te ra t u re 5] 3 GPP TS 2 5 .4 6 9 V e r .1 1 .1.0
[ Non P at ent Li te ra t u re 6] 3 GPP TS 2 5 .4 7 1 V e r .1 1 .1.0 [ Non P at ent Li te ra t u re 7] 3 GPP TS 3 6 .30 0 V e r .1 1 .4.0 [ Non P at ent Li te ra t u re 8] 3 GPP TS 3 6 .30 7 V e r .1 1 .2.0 [ Non P at ent Li te ra t u re 9] 3 GPP TS 3 6 .4 2 3 V e r .1 1 .3.0
25
Summary of Invention Technical Problem
[ 0007]
P at en t Li te rat u re 1 d oes not p r esent an y te ch niqu e for r edu cing
30 failures of a handover between HNBs. Non Patent Literature 1, Non
P at ent Li te rat u re 2 , N on P a ten t Lit e r at u r e 3, No n P at en t Lit e rat u re 5, and Non Patent Literature 6 disclose a handover between HNBs which are connected via Iurh. However, in the handover between HNBs conn e ct ed v ia Iurh as d isclose d i n t he abo ve -m enti oned p at ent

4
l i t erature , t ranspo rt l ayer I nfo r m ati on whi ch h as b een used for D L
( Down Li nk) b y a So ur ce HNB (s ou r ce b ase s tati on ) is n ot t ran smi t t ed
t o a Ta rget HN B ( ta r get bas e s t atio n ).
[ 0008]
5 As a result, when the Target HNB transmits a DL transport
information message to an HNB-GW (Home NodeB-GateWay), the t r anspo rt l ayer i nf o rmat io n , w hi ch i s a m and at or y p ara met er fo r t he DL t hat h as be en used b y t he Sou r ce HN B , can not be pr operl y s et, wh ich may cause a failure of the handover between the HNBs .
10 [0009]
It is an object of th e prese nt inv enti on t o provi de a commu nic ati on s yst em, a b as e st ati on, a ga te wa y devi ce , a b as e s tatio n control method, and a gateway device control method which are capable of reducing failures of a handover between HNBs and capable
15 of continuing communication.
Solution to Problem
[ 0010]
A fi rs t ex em pl a r y aspe ct of th e p r es ent i nve nt ion is a
20 commu nic a t i on s ystem in clu din g: a t erm inal; a firs t ba s e station t o
which the t ermin al is conn ec ted before m ovem ent; a secon d ba s e st at ion t o which th e t ermi nal i s con ne cte d after m ovem ent; and a gateway d ev i ce t hat con ne ct s t he fi r st bas e st atio n an d t he secon d base st at ion t o an up pe r n etwo rk so that the y a re ab le t o commu nic ate with
25 ea ch oth er. The fi rst bas e st atio n tra ns mit s , to t he s econd bas e s tat i on,
a fi rst si gnal to r equ est t he second b ase st ati on to s tart a h andov er, t he fi rst s ign al includi ng t ransp ort i nforma ti on w hic h has be en used fo r data d ow nlink d ata t r ans miss ion b y th e ga t ewa y de vi ce an d th e fi rst bas e s tat ion co mmun ic at ing w ith th e ga te wa y devi ce d uri ng a h ando ver
30 of th e te r mi nal . Th e s econ d ba s e sta tion recei ves t he fir st sign al a nd
t r ansmits, t o the gat eway de vic e, a s ec ond s ign al t o reque st t he gateway d ev i ce t o upd at e th e transp ort in fo rm atio n, th e s ec ond s ign al i nclu din g t he tra ns port info rm ation . The gateway d ev i ce receiv es th e s econ d si gnal an d han ds ove r th e tra nspo rt info rmatio n of t he fi rst bas e

5 st at ion t o a comm unicatio n with t he se cond b ase stati on. [ 0011]
A s econ d ex empl ary asp ect o f th e pre s ent inv enti on is a ba s e
st at ion i nclu din g t r ans miss ion m eans for t ransmi tti n g, wh en a hand ov er
5 o c curs d urin g commu nic ation with a termi nal , a fi rst si gnal to a s econd
bas e s tat ion, the fi rs t s ign al requ esti ng t he se con d b ase st ati on to st art t he hando ve r an d in cl udin g tra nsp ort in fo r m atio n which has b een use d f or do wnl ink data tra nsmi s si on by th e ba s e st ati on an d the gatewa y devi ce.
10 [0012]
A t hird ex em pl ar y aspe ct of th e pres ent i nvent ion i s a b ase st at ion i nclu din g : r ec eptio n me ans for r ec eivin g, wh en a ha ndov er of a t ermin al c omm uni cat in g wit h a firs t base s tat ion o cc urs, a fi rs t si gna l f or reque st i n g t o s tart the han dover, the first s ign al i ncludi ng t ran sp ort
15 i nformat ion wh ich h as b een used for do wnlin k dat a transmi ssio n b y t he
fi rst b as e s t atio n a nd a gate wa y devi ce; and tra nsm i s si on me ans for t r ansmitt ing, to th e gat ew a y de vice, a s eco nd s ign al to reque st th e gateway d ev i ce t o upd at e th e transp ort in fo rm atio n, th e s ec ond s ign al i nclu din g t he tra ns port info rm ation .
20 [0013]
A f ourth ex em pl ary asp ect o f t he pres ent in venti on is a gate wa y devi ce in cl ud ing : r ec eptio n me ans for r ec eivin g, wh en a ha ndov e r o f a t ermin al c omm uni cat in g wit h a firs t base s tat ion o cc urs, a se cond si gn al fo r req uesti ng t o up dat e t ranspo r t in forma ti on, th e s ec on d si gna l
25 bein g t r an smitt ed f r om a s eco nd bas e s tatio n an d inclu din g t he
t r anspo rt i nfo rmat ion whi ch h as been us ed for d ow nlink d ata t r ansmission b y t he fi rst ba s e statio n an d t he ga te wa y d evi ce ; and hand over m eans fo r h an di ng ov er t he t r ansport i nf orm atio n to a commu nic ati on with t he s econd b as e s tati on.
30 [0014]
A f i ft h ex emp l ar y a sp ec t o f t he p resent inv enti on is a m eth od for cont ro llin g a base st at ion , in cl ud ing: r ecei vin g, when a h an dover o f a t ermin al c omm uni cat ion wit h a firs t base s tat ion o cc urs, a fi rs t si gna l f or reque st in g to sta rt th e h and ov er, th e fi rst si gnal in clu di ng tra nsport

6
i nformat ion wh ich h as b een used f or down lin k data t r ansmi ss ion b y t he
fi rst b as e s t atio n a nd a gate wa y devi ce; and tra nsm i ttin g, t o t he
gateway d ev i ce, a s eco nd si gna l t o r equ est t he gat ew ay d ev ic e t o
updat e t he t rans po rt i nformat ion , the se co nd si gnal in cl udin g t he
5 t r anspo rt i nfo rmat ion.
[ 0015]
A six th ex em pl ar y as pe ct of the pres ent i nvent ion i s a metho d f or cont ro l l ing a gat eway de vic e, i ncludi ng: rec eiv i ng, whe n a hand over o f a t ermin al com muni ca ti ng w ith a first base st atio n o ccurs ,
10 a seco nd s ignal f or requ es tin g t o u pd ate t rans po rt in fo rmation , t he
s econ d si gnal b eing t r ansm itt ed from a se con d b ase sta t ion and i nclu din g t he tra ns port info rm ation whi ch has b ee n used for do wnlin k data t r ansmiss ion b y t he fi rst b as e st ation and t he gat e wa y d evi ce; and handi ng o ver the t r ansport in f orm at i on t o a commu ni cation wi t h th e
15 s econ d base stat ion.
Advantageous Effects of Invention
[ 0016]
Accordin g t o the p r esen t in ve ntio n, it is p os si bl e to p r ovid e a
20 commu nic a t i on s ystem , a b ase st ati on , a ga te wa y d ev i ce, a b as e s tat ion
control method, and a gateway device control method which are ca pab l e of red ucin g f ail ures o f a h an dov er b etw ee n HNBs and cap abl e of conti nui ng com muni cati on .
25 Brief Description of Drawings
[ 0017]
F i g. 1 i s a di agra m showi ng a co nfi gur ati on of a com muni cation s ys tem 100 0 a cco rdin g to a f irs t ex empl ar y e m bodi me nt o f the present i nven tion ;
30 Fig. 2 is a block diagram showing a configuration of HNBs 100
and 10 3 ac co rdi ng to the fi r st exem pla r y embo dim ent of th e present i nven tion ;
Fig. 3 is a block diagram showing a configuration of an HNB-GW 105 according to the first exemplary embodiment of the present

7 i nven tion ;
Fig. 4 is a diagram showing RAB handover elements of the HNB
100 that are transmitted from the HNB 100 to the HNB 103 according
t o t he fi rst ex empl ar y emb odim en t o f t he p r es en t in ventio n;
5 F i g. 5 i s a tab le sh owi ng co nfi gurati on s o f p ara m eters add ed t o
RANAP Enhanced Relocation Information Request in the first ex em plar y e m bo dime nt o f th e p r es en t in ven tio n;
Fig. 6 is a sequence diagram showi ng a process between HNBs in
which an HNBAP: TNL UPDATE REQUEST message is transmitted
10 from the HNB 103 to the HNB-GW 105 when a terminal 104 performs a
handover from the HNB 100 to the HNB 103;
F i g. 7 i s a dia gr a m sho win g transpo rt in format i on ele ments of
the HNB 103 that are transmitted from the HNB 103 to the HNB-GW
105 according to a second exemplary embodiment of the present
15 i nven tion ;
F i g. 8 i s a tab le in wh ich a pa ramet er o f Old Transpo r t i nfo
Invalid indicator is added to an HNBAP: TNL UPDATE REQUEST
message according to the secon d exemplary embodiment of the present
i nven tion ;
20 F i g. 9 i s a s equ en ce di agra m sho win g a pro ces s in which the
HNB 103 transmits the HNBAP: TNL UPDATE REQUEST message to the HNB-GW 105 according to the second exemplary embodiment of the present invention ;
F i g. 1 0 is a ta bl e in w hic h T r ans po rt La yer Ad dre ss and Iu
25 Transport Association are added to RNSAP Enhanced Relocation
Request as Source Side Iu DL TNL Information according to a third ex em plar y e m bo dime nt o f t h e p r es en t in ven tio n;
F i g. 1 1 is a ta ble in w hic h T r ans po rt La yer Ad dre ss and Iu
Transport Association are added to an RNA: CONNECT message as
30 Source Side Iu DL TNL Information according to a fourth exemplary
em bod ime nt of t he p r esen t i nve ntio n;
Fig. 12 is a table in which RAB ID, Old Transport Inf o, and New Transport Info are added in an RAB List when a Target HNB transmits an HNBAP Relocation Complete message to an HNB-GW according to a

8 t wel ft h ex em pl ary em bodim ent of th e pre s ent inv ent ion ;
F i g. 1 3 is a di agra m sho win g Iu r h In terfa ce fo r c om muni c ati on between an HNB and an HNB-GW;
F i g. 1 4 is a s eq ue nce di agra m sh owi ng a ha ndov er pro cess
5 between HNBs disclosed in Non Patent Literatu re 3; and
F i g. 1 5 is a di agra m sho win g Tran s po rt La yer Ad dres s e s used for a handover between HNBs connected via Iurh.
Description of Embodiments
10 [0018]
M att ers s tudied b y t he prese nt inv ent or to a chi eve the pres ent i nven tion will n o w be des crib ed . Non P ate nt Lit e r at u re 3 d efin es Iuh In t erface as a sta nd ard i nter f ac e for com municati on bet ween a n HN B (s m al l b ase st a t i on ) and an H NB - GW (ga te wa y d ev i ce). Iu r h In t erface
15 is presented as an interface for communication between HNBs. The
Iu h a nd Iurh int erface s will b e de s cri bed bel ow . [ 0019]
1. Iuh In te rfa c e
In a handover between HNBs, the HNBs transmit, to the HNB-
20 GW, an HNBAP (Home Node B Application Protocol): TNL (Transport
Network Layer) UPDATE REQUEST/RESPONSE message for updating
transport layer information, and an HNBAP: Relocation Complete
m es s age i ndicatin g the compl et ion of a ha ndover, b y usi ng Iu h
Interface. HNBAP (Home Node B Application Protocol), RANAP
25 (Radio Access Netwo rk Application Part), RUA (RANAP User
Ada p t at i on ), and S ABP (S ervi ce Are a Br oad c a st P r oto col ) are use d for Iu h In te r f ace. In oth er wo rds , the H N Bs use Iuh Int erfa ce t o
communicate with the HNB-GW (see Annex B in Non Patent Literature
3).
30 [0020]
2. Iu r h In terfa c e
H N B s t ransmit an d re cei ve d ata usin g c onn ecti on -orie nte d or conn ect ion les s d at a tra ns f er b et we en th e HN Bs via Iu r h Int erfac e . In a handover between HNBs, the HNBs transmit and receive RNA (RNSAP

9
(Radio Network Subsystem Application Part) User Adaption)
Co nn ect/Tran sfer/ Discon nect me ss ag e b y u sin g Iu rh In t e rfac e . Th e
RNA message can carry RNSAP message. RNSAP (Radio Network
Subsystem Application Part) and RNA (RNSAP User Adaption) are
5 us ed for Iurh Interfac e . In ot her w ords, a n HN B u s es Iurh Int erfa ce to
communicate with another HNB (see Annex B in Non Patent Literature 3). [ 0021]
F i g. 1 3 is a di agra m sho win g Iurh In terface fo r c om muni ca ti on
10 between an HNB and an HNB-GW. As shown in Fig. 13, the Iurh
In t erface h as t wo con ne ct ion m eth ods, i.e ., Direct Iurh an d Indi r ect Iu rh . Di re ct Iu rh is a conn ec tion method f or di r ec tl y con ne cting Iurh between H N B s. Indi r ect Iu r h is a method f or e st ablishi ng an Iurh connection between HNBs via t he HNB-GW, or a connection method
15 for establishing an Iurh connection between HNBs via an SeGW
(S ec u ri t y G at ew a y) (S ee A nn ex B in No n P at en t Lit e r at u re 3). [ 0022]
F i g. 1 4 is a s eq ue nce di agra m sh owi ng a ha ndo ver pro ce ss between HN Bs d is clo s ed i n N on P ate nt Lit e r at u r e 3. He r ei naft er, a
20 Source HNB is referred to as an HNB 100 and a Target HNB is referred
to as an HNB 103, as needed. [ 0023]
In step 1, the HNB 100 transmits an RNA CONNECT message to the HNB 103. The RNA Connect mess age includes, for example,
25 Message Type, Transaction ID, Cause value, Permanent NAS UE
Identity, and RANAP Enhanced Relocation Information Request. The RANAP Enhanced Relocation Information Request includes, for example, Message Type, Source RNC To Target RNC Transparent Container, and RABs (Radio Access Bearer) To Be Setup List.
30 [0024]
In step 2a, the HNB 103 requests the HNB-GW to update TNL ( T r ansp o rt Netw o r k La ye r ) info rm ati on (tra ns po rt i nformatio n). Accordingly, a message for transmitting an HNBAP: TNL UPDATE REQUEST message to the HNB-GW includes Message Type, Context-ID,

10
RAB (Radio Access Bearer) List, and Update Cause. Note that an RAB
Li s t IE ( Info rm ation El eme nt ) inc l udes RA B ID , Ol d Tran s port Info ,
New Transport Info, and CN Domain Indicator.
[ 0025]
5 In step 2b, the HNB-GW transmits an HNBAP: TNL UPDATE
RESPONSE message to the HNB 103. The message includes, for example, Message Type and Context-ID. Step 3 and subsequent steps are not dire ct l y as so ciat ed w ith this ex empl a r y e mb odiment , and t hus t he des criptio n th er e of wi ll b e om itt ed. In s tep 1, t he S ourc e H NB 1 0 0
10 t r ansmits the t ranspo r t l a yer i nformation to th e T arge t HN B 1 0 3, bu t
does not t r ans mit D L t ran sp ort l a yer in fo r m atio n w hic h h as be en us ed by the HNB 100. [ 0026]
In step 2a, the HNB 103 notifies the HNB-GW that DL data
15 transmitted from the HNB-GW is transmitted to the HNB 103 from the
HN B 1 0 0. A cco rdin gl y, i t i s n eces s ar y fo r the HN B 103 t o tra ns mit , t o the HNB-GW, the D L transport layer information on the HNB 103 and t he trans port l a ye r i nformati on whi ch h as been use d fo r th e D L b y th e HNB 100. However, since the HNB 103 cannot learn the transport
20 layer information on the HNB 100, the HNB 103 cannot transmit, to the
H N B -GW , th e tra nsp ort la yer info rm at ion whi ch has be en us ed fo r th e DL by the HNB 100. [ 0 027]
F i g. 1 5 is a di agra m sho wi ng Tran s port La ye r Add res s e s used for
25 a handover between HNBs connected via Iurh . The Transport Layer
Address is abb revi ate d as T L A dd r es s in Fi g. 15 . Fi g. 15 s ho ws t he Transport Layer Address used by HNBs in a handover between the HNBs. When the HNB 100 and an HNB-GW 105 are connected, the HNB 100 uses UL Transport Layer Address#2 of the HNB-GW 105 and
30 DL Transport La yer Address#1 of the HNB 100.
[ 0028]
The RANAP Enhanced Relocation Information Request, which is the RNA Connect message transmitted from the HNB 100 to the HNB 103, includes the UL Transport Layer Address#2 of the HNB-GW that

11
is transmitted to the HNB-GW from the HNB 100. However, the HNB
100 does not include, in the RANAP Enhanced Relocation Information
Re quest, the Transport Layer Address#1 of the Source HNB 100 which
has been used for the DL. Further, the HNB 100 notifies the HNB 103
5 of Trans port La yer Ad dres s# 4 u s ed for dat a for wa r di ng (data t r ans fer)
between the HNBs. In the above-mentioned process , the HNB 103 does not learn the Transport Layer Address#1 of the HNB 100. [ 0029]
After that, the HNB 103 transmits, to the HNB-GW, the HNBAP:
10 TNL UPDATE REQUEST in which Transport Layer Addresses used for
DL data transmission are included in Old Transport Info and New T r anspo rt Info , respe cti vel y. Ho we ver, s inc e th e H NB 103 d oes no t learn the Transport Layer Address#1 of the HNB 100, the HNB 103 ca nn ot set a corre ct v al ue fo r Ol d T r anspo r t In f o IE . Add it i on all y,
15 there is a problem that the HNB-GW cannot verify a change from any
one of DL Transport Layer Addresses to the Transport Layer Address of the Target HNB 103. [ 0030]
As a result, in the handover between the HNBs, the HNB-GW
20 ca nn ot p ro perl y se t m an dato ry pa r amet ers an d t hus can not v eri fy a
change from any one of the DL Transport Layer Addresses to the Transport La yer Address of the Target HNB. This may cause a failure of the handover between the HNBs . The present invention has been made in view of the above-mentioned problems.
25 [0031]
First Exemplary Embodiment
In a communication system 1000 according to this exemplary embodiment, during a handover (H/O) between HNBs using Iurh In t erface b etween H N Bs, a Sou r ce H NB 1 0 0 ( f i rs t base st atio n)
30 transmits information about the Source HNB 100 to a Target HNB 103
(second base s tat ion ) . Sp ecifi cal l y, i n a cas e wh ere the S ourc e H NB 100 receives data from an HNB-GW 105 (gateway device), the Source H N B 100 r eceive s D L tran spo rt l a ye r i nform at i on . In t hi s case, durin g the handover, the Source HNB 100 transmits, to the Target HNB 103,

12 t he DL trans po rt layer in fo rm ati on ( tr an spo rt i nformat ion ) whic h ha s be en us ed fo r d ownli nk d at a transmi ss ion . [ 0032]
Further, in the communication system 1000, the Target HNB 103
5 t r ansmits , to th e H NB -GW 105, t he DL t r an s port laye r i n fo r mati on
which has been used by the Source HNB 100. The HNB-GW 105 is confi gure d to p rop erl y h an d ov er the D L tra ns po rt laye r i nfo rmati on f or th e S ou rce HN B 100 to the DL tra ns port layer info rmati on for the Target HNB 103 in the Iurh handover.
10 [0033]
F i g. 1 i s a di agra m showi ng th e con fi gur a tio n of t he commu nic a t i on s ystem 10 00 a cc ordin g t o th e fi rst ex empl ary
embodiment of the present invention. The communication system 1000 includes the HNB 100, the HNB 103, the HNB-GW 105, and a terminal
15 104. The HNB 100 and the HNB 103 are HNBs having an interface to
ex ch an ge cell i nform ati on a nd han do ve r info rm ati on ab out U E (User Equipment) in the handover between the HNBs . The HNB 100 and the HNB 103 communicate with each other via the Iurh Interface. [ 0034]
20 The HNB-GW 105 communicates with the HNB 100 and the HNB
103 v i a the Iuh Int e r f ac e , an d cont ro ls and mana ges t he con ne cti on with the HNBs. The HNB-GW 105 connects the HNB 100 and the HNB 103 t o an u pp e r netwo rk so t hat th e y a re abl e to com muni ca t e wit h each other. The HNB-GW 105 also includes an interface. The terminal
25 104 i s a mo bile termina l ( mob i l e s tat ion ) that pe r fo rms rad i o
communication with the HNB 100 and the HNB 103. A cell 101 which i s co ntrol l ed b y t he HNB 100 and a cell 1 02 whi ch is con trolle d b y th e HN B 1 03 are adja ce nt t o ea ch oth er . In t hi s c as e, Iu r h In ter f ac e i s us ed as an i nterf ac e bet ween th e H N Bs. Th at is , t he comm unication
30 s ys tem 1 000 is a sys t em in w hi ch ra di o com mun ic ati on is est ablish ed
among the HNBs 100 and 103, the HNB-GW 105, and the terminal 104. [ 0035]
F i g. 2 i s a bl ock d ia gr am sh owin g the co nfigu r ati on o f th e HNBs 100 and 103 a cco rdin g t o t he fi rst ex empl a r y e m bo dim ent o f th e

13
present invention . The HNBs 100 and 103 each include a radio
commu nic a t i on p ro cessi ng un it 2 0 0, an i nte r - ba s e- s t at ion mess age
processing unit 201, an HNB-GW 202 communication unit, and
database means 203. The radio communication processing unit 200
5 t r an smits in f orm atio n to t he t e r min al 10 4 and r eceives in f orm atio n
f r om t he t ermi n a l 10 4 . In oth er wo r ds, th e r adi o com muni c ati on proc essin g uni t 2 0 0 se rv es as tra ns mis si on me a ns f or t rans mitti ng i nform at ion t o th e t ermin al 1 04 a nd a s re ce pt ion m e an s fo r re ce iv ing i nform at ion f ro m t he t e rmin al 10 4.
10 [0036]
The inter-HNB message processing unit 201 transmits and r ecei ves h andov er in f orm atio n necessar y for a h and ove r. In ot he r words, t he i nter-H NB mess age pro ce ss ing u nit 201 se r ves as t r ansmission mean s fo r tran sm itti ng info rm at ion t o t he H NB s and as
15 r eceptio n m ean s fo r re ce i ving i nformati on from th e HNBs .
[ 0037]
The HNB-GW communication unit 202 transmits and receives hand over i nfo rmat ion n ecess ar y fo r p erformin g a ha ndover with th e HNB-GW 105 by using the Iuh Interface. In other words, the HNB-GW
20 commu nic a t i on un it 2 02 se rv es as t r ans miss ion m eans fo r t ra n sm ittin g
information to the HNB-GW 105 and as reception means for receiving information from the HNB -GW 105. [ 0038]
In th e dat ab as e m e ans 203 , t ermin al in form atio n sto red in t he
25 database means and HNB i nformation on the corresponding HNB are
updat ed as n e eded b y th e i nte r - HN B mess age pr oc ess in g unit and th e HNB-GW communication unit. [ 0039]
F i g. 3 i s block di a gr am showing t he con figu r atio n of t he H NB -
30 GW 105 according to the first exemplary embodiment of the present
invention. The HNB-GW 105 includes handover means 300, HNB communication means 301, and database means 302. The HNB communication means 301 transmits information to the HNBs 100 and 103 and receives information from the HNBs 100 and 103 . The HNB-

14
GW 1 05 a lso t r ansmits an d r eceives han dover i n form at ion nece ssa r y
for performing a handover with the HNBs 100 and 103 by using the Iuh
Interface.
[ 0040]
5 In other words , the HNB communication means 301 serves as
t r ansmission mean s fo r tran sm it tin g info rmat ion t o t he H N Bs 100 and 103 and as reception means for receiving information from the HNBs 100 and 103. The handover means 300 switches the communication destination HNB of the HNB communicatio n means 301 during the
10 hand over based on t he ha ndo ve r in f orma tion . In t he d atabas e m e ans
302, the stored terminal information and the HNB-GW information of the corresponding HNB are updated as needed by the HNB communication means 301. [ 0041]
15 Fig. 4 is a diagram showing RAB handover information elements
of the HNB 100 that are transmitted from the HNB 100 to t he HNB 103 and are included in RANAP Enhanced Relocation Information Request ac cordin g t o the fi rst exe m plary em bodim ent o f th e pres ent in venti on . [ 0042]
20 The RAB handover information elements transmitted from the
HNB 100 to the HNB 103 are as follows.
- RAB information on the HNB 100
- Transport layer information on the HNB 100 [ 0043]
25 F i g. 5 i s a tab le sh owin g co nfi gurati on s o f p aram ete r s add ed t o
the RANAP Enhanced Relocation Information Request in this
exemplary embodiment. In this exemplary embodiment, Source Side Iu DL TNL Information IE is added in an IE as DL transport layer i nformat ion . In t his exe mpl a r y e m bo dime nt , t he IE in cludes U L
30 t r anspo rt i nfo rm atio n of t he H NB - GW 1 05 tha t is tra nsmi tted f r om the
HNB 100 to the HNB-GW. [ 0044]
That is , t he S ou r ce Sid e Iu DL T N L Inform atio n IE th at i s transmitted from the HNB 100 to the HNB 103 in the first exemplary

15
em b odiment i s def ine d as an IE di ffere nt fro m the S ource Si de Iu U L
TNL Information IE of the 3GPP. The RANAP Enhanced Relocation
In fo rmati on R e quest ac cordin g to th e firs t ex empl a r y e mb odim ent i s
r eferred to as a fi rst s i gn al. Not e t hat t he in fo r m atio n to be
5 transmitted from the Source HNB 100 to the Target HNB 103 may be
included in any one of RNA, RNSAP, and RANAP messages. [ 0045] Explanation of Processing of First Exemplary Embodiment
Processing of the communication system 1000 according to the
10 fi r st ex em pl ar y em bo dim en t w ill be d esc ri bed b elow . In th e follo win g
des crip tion , t he comp one nt s o f t he H NB 10 0 a r e d en oted us i ng a reference symbol "a" and the components of the HNB 103 are denoted us in g a re f eren ce s ymbol "b " in order t o di st ingu ish t he comp on en ts of the HNB 100 from the components of the HNB 103 .
15 [0046]
A process in Direct Iurh connection between the HNB 100 and the HNB 103 according to the exemplary embodiment as described below corresponds to RNA Connect message (step 1) during the hand over b etween the HNBs sho wn i n Fig. 14 . Sp eci fi cal l y, durin g the
20 handover, the HNB 100 transmits, to the HNB 103, the RANAP
En han ced R e lo cation In f orm ati on Re quest (first si gnal ) t o requ es t the HNB 103 to start the handover. [ 0047]
F i g. 6 i s a s equ en ce di agra m sho win g t he p ro cess b etw ee n the
25 HNBs in which an HNBAP: TNL UPDATE REQUEST message (second
si gn al ) to r equest the HN B - GW 105 to u pda t e the t r an s port info rm ation is transmitted from the HNB 103 to the HNB-GW 105 when the terminal 104 performs a handover from the HNB 100 to the HNB 103. [ 0048]
30 The HNB 100 communicates with the terminal 104 through a
r adi o commu ni c a tion p r oc essin g uni t 2 0 0 a. T h e t e rm inal 104 m ove s t o a p os itio n withi n th e range of t he cel l 102 from a p osit ion wi thin t he r ange of the c el l 1 01. T he t e rmin al 10 4 ne eds t o ha nd over t he communication destination from the HNB 100 to the HNB 103.

16 [ 0049]
During t he ha ndo ve r , in a n in te r -H NB m es s age p r ocessin g unit
201a of the Source HNB 100, database means 203a reads out the DL
t r anspo rt l ayer i nf orm at ion (t r ans port in f orm ati on) on t he So urc e HNB
5 100. The inter-HNB message processing unit 201a of the HNB 100
transmits an RNA: Connect message to the HNB 103 (S011). At this time, the RNA CONNECT message includes the RANAP Enhanced Re lo catio n Info rmat ion R equ est ( fi r s t sign al ) as s how n i n Fig. 5 . In t hi s case , t he i nter-H NB mess age pro ce ssing u nit 201 a transmits t he
10 RANAP Enhanced Relocation Information Request (first signal)
including the Source Side Iu DL TNL Information IE information (transport information) to the HNB 103. [ 0050]
A message processing unit 201b of the HNB 103 receives the
15 RANAP Enhanced Relocation Information Reques t in which the Source
Side Iu DL TNL Information IE information is added. The message processing unit 201b of the HNB 103 stores the Source Side Iu DL TNL In fo rmati on IE (t rans port i nfo rm ati on ) in dat ab as e m e ans 20 3b. A n HNB-GW communication unit 202b of the HNB 103 reads out the
20 Source Side Iu DL TNL Information IE (transport information) from
the database means 203b. The HNB-GW communication unit 202b of the HNB 103 transmits an HNBAP: TNL UPDATE REQUEST (second signal) to the HNB-GW 105 (S012). [ 0051]
25 At this time, the HNB-GW communication unit 202b of the HNB
103 transmits the HNBAP: TNL UPDATE REQUEST message (second si gn a l ) i nclu din g t he So urc e S i de Iu D L TN L Info r mat ion IE (transpo rt information). The HNB communication means 301 of the HNB-GW 105 receives the HNBAP: TNL UPDATE REQUEST (second signal)
30 including the Source Side Iu DL TNL Information IE. The HNB
communication means 301 of the HNB-GW 105 stores the DL transport l a yer i nformat ion in t he d ata ba s e m e ans 30 2. B y th is pro cess, t he HNB-GW 105 hands over the DL transport layer information for the S ource HN B 1 0 0 a s the DL t r an spo rt l a ye r in f orma t i on for th e T arge t

17 HNB 103. [ 0052]
The HNB communication means 301 of the HNB-GW 105
transmits an HNBAP: TNL UPDATE RESPONSE message to the HNB
5 103 . In t he su bs equent p ro cess (c orrespon din g to st ep 3 and
su bsequ ent steps sho wn in Fig. 1 4 ) , t he h ando ver m eans 30 0 of th e HNB-GW 105 reads out the DL transport layer information from the database m ean s 3 02 a nd s witc he s the co mmun ic at ion d estin at ion o f t h e HNB communication means 301 from the HNB 100 to the HNB 103
10 based on the DL transport layer information for the HNB 100. The
HNB 103 communicates with the terminal 104 through a radio commu nic ati on p roc es si ng unit 2 00b bas ed o n th e D L t ranspo r t l a ye r information for the HNB 100, and the handover ends. [ 0053]
15 Ex pl an ati on o f Ad van tageous Eff ects
As described above , in the communication system 1000 ac cordin g t o the fi rst ex emp la r y em bod ime nt o f th e pres ent in venti on , the HNB 100 transmits the Source Side Iu DL TNL Information (first si gn al ) to t he HNB 10 3, th ereb y en ab lin g th e hand ov er of the DL
20 t r anspo rt l ayer i nf orm atio n be t w een th e HN Bs . Furth er, in t he
communication system 1000, the HNBs can properly set the DL t r anspo rt l ayer i nf orm atio n in th e H N B-GW 10 5, t he r eb y makin g it poss ib le t o r educe fail ures of the h and over b etw een th e HN Bs. Furthermore, in the communication system 1000, the HNB-GW 105 can
25 verify a change from any one of the DL Transport Laye r Addresses to
the Transport Layer Address of the Target HNB 103. [ 0054] Second Exemplary Embodiment
As des cri ed abo ve regard ing th e mat t ers r evi ew ed b y th e presen t
30 i nven tor , i n step 2a s how n in Fi g. 1 4, the HN B 103 tra ns mit s , to t he
HNB-GW, the HNBAP: TNL UPDATE REQUEST in which Transport La yer Ad dre ss es used for D L d at a tra ns mi ssio n are in clu ded i n Ol d T r anspo rt Info a nd Ne w Tran s port In fo , r es pect iv el y. Ol d T ransp ort La ye r IE is a ma nd at or y pa r am ete r .

18 [ 0055]
However, if the HNB 100 does not transmit, to the Target HNB
103, the t r ans po rt la yer i nform a t ion wh ic h h as be en us ed for the D L o f
the HNB 100, the HNB 103 does not learn the transport layer
5 information on the HNB 100 in the HNBAP message , and thus cannot
s et a co r r ect v alu e for Ol d Trans port Info IE. [ 0056]
If t he S ou rce H NB 1 0 0 tran smit s inc orre ct D L tra nsp ort la yer
information on the Source HNB 100 to the HNB-GW 105, the HNB-GW
10 105 m a y set i nco rre ct D L tran spo rt la yer info rm ation .
[ 0057]
In th is c ase, th e HNB 1 03 c anno t r ec ei ve t he D L data t r ansferred
from the HNB-GW 105 to the HNB 100. Further, the terminal that
performs a handover from the HNB 100 to the HNB 103 may be
15 disconnected from the service used in the HNB 100, and thus may not
us e t he se r vi ce conti nuou sl y . [ 0058]
A case where the Target HNB 103 transmits the HNBAP message
to the HNB-GW 105 during a handover between the HNBs which
20 commu nic at e with e ac h ot her v ia the Iu r h Int erfa c e w ill be consid ered .
During the handover between the HNBs disclosed in Non Patent
Literature 3, the Target HNB transmits the HNBAP: TNL UPDATE
REQUEST message to the HNB-GW (step 2 shown in Fig. 14). The
HNBAP is a control protocol for the HNB network over the Iuh
25 Interface.
[ 0059]
The HNBAP protocol provides the following functions.
- Registration of HNB-GW and HNB
- Identi fi cat i on of H N B
30 - Registration o f HNB-GW and UE through HNB
[ 0060]
P ro cessin g of t he c om muni ca ti on s ystem 10 00 a cc ordin g t o thi s exemplary embodiment corresponds to transmission of the HNBAP: TNL UPDATE REQUEST (step 2a shown in Fig. 14) between the HNBs

19
and the HNB-GW as shown in Fig. 14. The communication system
1000 acc ordin g t o this exempl a r y e m bodi men t is c onfigu r ed t o be abl e
to change the HNBAP message to be transmitted from the Target HNB
103 to the HNB-GW 105.
5 [0061]
In this exemplary embodiment, the communication system 1000 s et s an Invalid i nd icat or to dis abl e s etti ng of the transpo r t l a yer i nformat ion , to the r eb y el im inate th e need for t he T arge t HNB 1 03 to s et , in t he HNB -G W 10 5, t he trans po rt layer in f orm ati on wh ich has
10 been used by the Source HNB 100. Then the HNB 103 disables the DL
t r anspo rt l ayer i nf orm atio n an d t r ans mits t he disab le d in form atio n to the HNB-GW 105. [ 0062]
S peci f ic al l y, co nfi guration in f ormati on: Inv alid i ndi cato r to
15 di s abl e setti ng o f the D L t r ans po rt l a yer in f orm ati on o n th e So ur ce
HNB 100 is added to the HNBAP TNL UPDATE REQUEST message (second si gna l ) to be t ran sm itt ed fro m t he Ta r get HNB 10 3 to th e HNB-GW 105, and the HNBAP message including the configuration i nformat ion i s t ransmitted .
20 [0063]
In ot he r w ords , w hil e t he T arget H NB 10 3 tra ns mit s , t o th e HNB-GW 105, the transport layer information on the Source HNB 100, t he Ta rget H NB 103 set s t he con f igu r at ion i nformat ion: Inv alid i ndicato r t o disa ble s ettin g of th e t ranspo r t la yer info r mati on on th e
25 S ource HN B 1 00 th at i s a m an d at o r y pa r am ete r , a nd t r ansmits th e set
information to the HNB-GW 105. [ 0064]
F i g. 7 i s a dia gr a m sho win g transpo rt in format ion el eme nts o f the HNB 103 that are transmitted to the HNB -GW 105 from the HNB
30 103 according to the second exemplary embodiment of the present
i nven tion . F i g. 8 is a tab le in which a c on fi gu rati on i nfo rm atio n pa ram ete r o f O ld T r anspo rt in f o In val id in di cator is a dded t o th e HNBAP: TNL UPDATE REQUEST message (second signal) according t o t he se con d exempla r y embo dim ent o f th e p r es ent in ven tion .

20 [ 0065]
Inf ormati on e l ements to be t r ansmitted f r om t he HN B 1 03 to t he HNB-GW 105 are as follows.
- RAB information on the terminal 104
5 - Inv alid i ndicato r t o elimi nat e t he n ee d f or set tin g th e T ran sp ort
Layer Address of the HNB 100 [ 0066]
Ex pl an ati on o f P r ocessin g [ 0067]
10 Processing of the communication system 1000 according to the
second exemplary embodiment will be described. As shown in Fig. 8, when the HNB 103 transmits the HNBAP: TNL UPDATE REQUEST message (second signal) to the HNB-GW 105, the HNB 103 adds new confi gurat ion in fo rm ation to th e HNBAP m es sage t o be trans mitt ed .
15 [0068]
F i g. 9 i s a seq ue nce d ia gr am s howi ng a p roces s in wh ic h th e HNB 103 transmits the HNBAP: TNL UPDATE REQUEST message to the HNB-GW 105 according to the second exemplary embodiment of the present invention .
20 [0069]
During a handover of the terminal 104 from the Source HNB 100 to the Target HNB 103, when the Source HNB 100 does not transmit, to t he Ta rget H NB 103, th e transpo r t la ye r info rm ation whi ch has b ee n used for the DL of the Source HNB 100, the Target HNB 103 does not
25 r ecei ve t he tran s po rt layer in f orm ati on wh ich h as be en u s ed fo r the D L
of the Source HNB 100. [ 0070]
The inter-HNB message processing unit 201b of the Source HNB 103 reads out HNBAP TNL UPDATE Request message infor mation on
30 the Source HNB 103 from the database means 203b. The inter-HNB
message processing unit 201b of the HNB 103 transmits, to the HNB-GW 105, the HNBAP TNL UPDATE Request message (second signal) of t he HN B 1 03 i ncl udi ng t he co nfi gu r a tion in fo rm atio n of Old T ranspo rt i nfo In v alid i ndi c at o r (S1 01 ).

21 [ 0071]
The HNB communication means 301 of the HNB-GW 105
receives the HNBAP TNL UPDATE Request mess age (second signal).
The HNB communication means 301 of the HNB-GW 105 stores the
5 HNBAP TNL UPDATE Request message information including the
confi gu r at ion i nfo rm ati on o f O ld Tra ns port i nf o In v alid i nd icat o r in the database means 302. The HNB communication means 301 of the HNB-GW 105 transmits the HNBAP: TNL UPDATE RESPONSE m es s a ge (t hird sig nal ) to the H NB 103 .
10 [0072]
In th e subsequ ent proc ess ( co rrespo ndi ng t o s tep 3 and su bsequ ent steps sho wn in Fig. 1 4 ) , t he h and ov er m e an s 30 0 of the HNB-GW 105 reads out , from the database means 302, the DL transport l a yer i nformat ion on t he HNB 1 00 curren tl y com muni cat i ng t her ewit h,
15 and switches the communication destination of the HNB communication
means 301 from the HNB 100 to the HNB 103 based on the DL t r anspo rt l ayer i nf orm atio n . [ 0073]
The HNB-GW 105 transmits the DL data from the HNB 100 to
20 the HNB 103. The HNB 103 hands over the communication with the
t ermin al 10 4 t hrou gh t he rad io comm uni c atio n pro cessi ng un it 2 0 0b . The HNB 103 communicates with the terminal 104 through the radio commu nic a t i on p ro cessi ng un it 2 0 0b , a nd the h ando ve r ends. [ 0074]
25 Ex pl an ati on o f Ad v an ta geous Eff ects
As d es crib ed ab ove , th e D L tran sp ort l a ye r i nform atio n whic h has been used by the Source HNB 100 is not transmitted from the Source HNB 100 to the Target HNB 103 in some cases during a handover. On the other hand , the communication system 1000
30 ac cordin g t o this e xempl ar y em bodi ment s ets th e co nfi gu rati on
i nfo rm at ion : Old T ran s port in fo Inv alid i ndica t o r, th ere by ena bli ng t he hand over b etween the HNBs usin g t he Iu r h Int erfa ce wi thou t s et tin g the DL transport layer information on the Source HNB 100. [ 0075]

22
Third Exemplary Embodiment
In t his ex empl a r y em bod ime nt , as sh own in Fig. 10 , Trans port
Layer Address and Iu Transport Association may be set as Source Side
Iu DL TNL Information in an RNSAP Enhanced Relocation Request
5 ( fi r st s ign a l ) . Th e p roc es si ng of th e com munica tion s ystem 10 0 0 is
simil ar to t hat of th e f i rs t exem pl ar y embo dim ent .
[ 0076]
Fourth Exemplary Embodiment
In t his ex empl a r y em bod ime nt , as sh own in Fig. 11 , Trans port
10 Layer Address and Iu Transport Association may be added an d set as
Source Side Iu DL TNL Information in an RNA: CONNECT message .
Th e proc ess in g of th e co mm uni c atio n s ys te m 1000 i s si mil ar to t hat of
t he fi r st ex emp l ary em bo dim en t.
[ 0077]
15 Fifth Exemplary Embodiment
In t his ex empl a r y em bod ime nt , D L t r ans port l a yer info rmati on
on the Source HNB 100 may be handed over by Indirect Iurh Interface
between HNBs via the HNB-GW 105 and an SeGW. The processing of
t he commun ic at io n s yst em 10 00 is s i milar t o t hat o f t he fi rst exe mpl ar y
20 embodiment.
[ 0078]
Sixth Exemplary Embodiment
In this exemplary embodiment, Old Transport Info of an HNBAP:
TNL UPDATE REQUEST (DL transport layer information which has
25 been used by the HNB 100) may be changed from a mandatory
pa r ameter t o an op tion p ara met er, an d th e D L tran spo rt l a ye r
i nformat ion m a y n ot be set . The pro cessin g o f t he c ommu ni c ati on
s ys tem 1 000 is si mila r to t hat o f th e se co nd exempl a r y e mb odim en t.
[ 0079]
30 Seventh Exemplary Embodiment
In t his ex empl a r y em bod ime nt , O ld Transpo rt i nfo In v al id
indicator may be added in an RUA message (Non Patent Literature 4)
for encapsulating and transferring an RANAP message between the
HNB and the HNB-GW. The processing of the communication system

23 10 0 0 i s s imil ar t o that of th e s eco nd ex empl a r y e mb odi ment . Eighth Exemplary Embodiment
In t his ex empl a r y em bod ime nt , t he p ro cessin g th at is p erform ed
during a handover between HNBs may also be performed during a
5 handover from the HNB to other radio base stations (eNB, HeNB,
Donor eNB, Relay Node, RNC, etc.). The processing of the commu nic a t i on s ystem 10 0 0 is s im ilar t o th at o f t he firs t an d secon d embodiments. [ 0080]
10 Ninth Exemplary Embodiment
In t his ex empl a r y em bod ime nt , t he i nformati on to be tra ns mi t ted from the Source HNB 100 to the Target HNB 103 may include MDT (Minim iz at io n of D riv e T ests, Non P at ent Li terat u re 8 ), in f ormation about t he occurre nc e o f a radio l ink fai lure ( Non P ate nt Li terat u re 7 ),
15 U E hi st o r y in fo rm atio n (No n P at ent Li tera t u r e 9), l o c atio n in fo rmat ion
(Non Patent Literature 1), information about a Source HNB-GW, information about a Source SGSN and a Source MSC , information about IP -P BX, i nfo rm atio n abo ut a l oc al GW , l oc al se rv e r in f ormation (for LIPA, SIPTO), PLMN information, and in-house GW information.
20 [0081]
Tenth Exemplary Embodiment
In t his ex empl a r y em bod ime nt , t he p r ocessin g th at is p erform ed during a handover between HNBs may also be performed during a handover from the HNB to a Wi -Fi® (wireless LAN) device, such as
25 Access Point for wireless LAN, W LC (Wireless LAN Control), MAG
(Mobility Access Gateway), or WAG (Wi -Fi Access Gateway). The processin g of t he com m unica tion s ystem 10 0 0 is s i m ilar t o t hat o f t he ninth exemplary embodiment. [ 0082]
30 Eleventh Exemplary Embodiment
The proc ess in g of th e co mm uni c atio n s ys tem 1000 i s si mil ar to t hat o f the f i rst ex em pl ar y e mb odim ent . In thi s ex emp l ar y embo di ment , t he s am e pro ces si ng a s th at of t he fi r st ex emp la r y e m bo dime nt may b e performed in any protocol other than RNSAP and RNA protocols.

24
[ 0083]
Twelfth Exemplary Embodiment
The con f igu rat ion of th e comm unica tio n s ys tem 1 000 i s simi l ar
t o t hat o f th e fi rst exempl a r y e m b odi m ent . In t his ex empl ar y
5 embodiment, when the Target HNB transmits an HNBAP Relocation
Complete message to the HNB -GW in step 7 shown in Fig. 14, the RAB
List in which RAB ID, Old Transport Info, and New Transport Info are
added as shown in Fig. 12 may be transmitted.
[ 0084]
10 Ex pl an ati on o f Ad van tageous Eff ects
The t hird , fourt h, fi fth , ele venth , and t welfth ex emp l ary
em b odiment s prov ide t he s ame adv antageo us e f f ec ts as th os e of the
fi r st ex em pl ar y em bo dim ent. T he six t h an d s even th ex emplary
em bod ime nt s prov ide t he s ame advanta geou s ef f ec t s as thos e o f th e
15 second exemplary embodiment. The eighth exemplary embodiment
provid es the s ame adva nt ageou s ef f ects as t hos e of th e fi rst and s econd
exemplary embodiments.
[ 0085]
The nint h ex emp l ar y em bo dim ent h as an a dva nt ageou s effe ct t hat
20 the Source HNB can properly hand over communication log information,
network in form ati on, wi r el ess i nfo r matio n, and po sit ion al info rm ation
t o the T arget HN B , th ereb y ma king i t possib le to p erform a hando ve r
su ccessful l y and con ti nue th e comm uni ca t i on.
[ 0086]
25 The t en th ex em pl ar y em bo dim ent h a s an a dva nt ageou s effe ct t hat
i t is po ssi bl e to p r operl y h an d o ve r c ommu ni cation l og info rm at ion ,
network i nfo rm at ion , wi r el ess i nfo r matio n , an d p osit ion al info rm ati on
also in a handover from the HNB to a Wi -Fi device, thereby making it
possib le t o perform t he ha ndov er s uc ce ss full y a nd co ntin ue th e
30 communication.
[ 0087]
Other Exemplary Embodiments
The method for controlling the HNBs described above may be
i m plem ent ed usin g a semi con duc t or pro cessi ng d evi ce in clud ing an

25
AS IC ( Appli c at ion S pe cifi c Int eg ra te d Ci r cuit ) . Fu r ther, the pro ce sse s
may be implemented by causing a compute r system including at least
one processo r ( e.g. a m ic ro pro ces so r , MP U, or DSP (D igit al Si gnal
P r oc esso r) ) t o execut e a pro gr am . Sp ecificall y, o ne o r mo r e program s
5 i nclu din g a n in st r uctio n s et fo r caus ing the com puter sys te m t o ex ec ut e
an al gorith m for th e t r ansm is si on si gnal pro ces si ng or recep tion sign al processing may be created and the created programs may be provided to a computer. [ 0088]
10 These programs can be stored and provided to a computer using
an y t yp e o f non - t ransit or y com put er r ead abl e medi a. Non -tran si tory compu ter re adable m edi a i ncl ud e an y t yp e of t angi bl e sto rage m edi a. [ 0089]
Exampl es of n on -t r ans ito r y c om pu ter r ead able m edi a incl ud e
15 m agneti c st orage med ia (suc h as fl opp y d is ks , m agnetic t ap es, ha r d
di sk dr iv es , et c. ) , optical m agn et ic sto r age m edi a (e . g. magneto -opti ca l disks), CD-ROM (Read Only Memory), CD-R, CD-R/W, and semiconductor memories (such as mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access
20 m emor y), e tc. ) .
[ 0090]
The programs may be provided to a computer using any type of t r ansito r y co mp ute r r eadable m e dia . Ex amp les of tran sito ry c om puter r ead abl e medi a in clu de el ect r ic si gna ls, optical signals, and
25 el ectrom agn etic wa ves. Tran si tory c ompu te r reada bl e medi a ca n
provid e th e pro gr a m s t o a com put er vi a a w ired commu ni cation l ine,
su ch as el ec t ri c wi r es an d optical fib ers, or a wi rele ss c om muni ca ti on
line.
[ 0091]
30 Note t hat t he p re s ent inv ent ion is no t lim ite d t o the ab ove
exemplary embodiments, and can be modified as appropriate without departin g f rom t he sc op e o f th e i nv enti on . [ 0092]
The above exemplary embodiments are merely examples of the

26
appli cation of th e te chni cal idea o bt ai ned b y th e prese nt i nvento r .
Th at is , t he techn ic al idea is not lim ited onl y t o th e abov e ex empl ar y
em bod ime nt s, but can b e m odi fi ed in var ious ways .
[ 0093]
5 For example, the whole or part of the exemplary embodiments
di s close d abov e c an b e d esc ri bed as, bu t not limi ted to , t he follo win g su pp lem ent ar y not es. (S up pl eme nta r y no te 1)
A communication system comprising:
10 a terminal;
a fi rst b ase st ati on t o which th e t ermin al is con n ect ed b efo re movement;
a seco nd ba se st ation to wh ich t he t erm ina l is c onnecte d aft er
movement; and
15 a gat ew a y dev ice th at con ne cts th e fi rs t ba s e statio n and th e
s econ d base stat ion to an upp er ne t wo rk so t hat th e y ar e abl e to communicate with each other, wherein
t he fi r st b as e st ati on t r ans mits, to the se co nd b ase st at i on, a
fi rst s ign al to re que st t he s econd b ase s tati on to st art a ha ndov er, t he
20 fi rst s ign al includi ng t ransp ort i nforma ti on whi ch has b een used f or
downl ink d ata t ransmis si on b y t he ga te w a y d evice a nd t he fi rst base st at ion commu nicatin g with t he gat e wa y de vi ce du ri ng a h and ove r o f t he ter min al ,
t he second b ase s tat ion r ec ei ves t he fi r st si gn a l an d tra nsmit s , to
25 t he gate wa y devi ce , a second si gnal to r equest th e gateway d ev i ce t o
updat e t he t rans po rt i nformat ion , the se co nd si gnal in cl udin g t he t r an spo rt i nfo r m at ion, a nd
t he g at ew a y de vice r ec ei ves t he se con d si gnal a nd han ds o ve r th e
t r anspo rt i nfo rmat ion of t he fi rst b as e st atio n to a co mmu ni cation wi th
30 t he se cond b ase s tat ion .
(S up pl em entar y n o t e 2)
The communication system according to Supplementary note 1, wherein t he secon d base station t r an smi ts, to th e gat ew a y dev ice, the s econ d si gnal i ncl udin g con fi gurati on in f orm ati on to disable s ett ing o f

27 t he t r ans po r t i nfo r mati on. (S up pl eme nt ary n o te 3)
The communication system according to Supplementary note 1 or
2, wh ere in t he fi r s t base s tat ion tra nsmi ts t he first s ign al t o the secon d
5 bas e s tat ion vi a the gatewa y d evi ce.
(S up pl eme nta r y no te 4)
A b ase sta t i on comp ri sin g tran smissio n me an s for t ran smi ttin g,
when a ha ndo ver oc cu rs d urin g comm uni cat ion wit h a t erm ina l, a fi rst
si gn al t o a s ec ond b as e s tat io n, the firs t s ign al req ue st in g t he se cond
10 bas e s tat ion to sta rt th e ha ndo ver an d inc ludi ng tran s po rt in fo r mati on
which has b een use d f or do wnlink da ta t ran smi s si on b y th e t r ansmission mean s a nd a ga te wa y devi ce . (S up pl eme nta r y no te 5)
The base st at ion ac co rdin g to Supp lemen tary not e 4, wh erei n the
15 t r an smission m e an s t r ansm its the first s ign al t o th e secon d ba s e statio n
via the gateway device. (S up pl eme nta r y no te 6)
A b ase sta t i on comp ri sin g:
r eceptio n m ean f or re ceivi ng, when a ha ndov er of a termina l
20 commu nic ati ng with a fi rst b as e s t at i on occu rs, a fi r st sign al fo r
r equest ing t o st art th e ha ndov er, th e first s i gnal inc ludin g t r anspo rt
i nfo rmat ion which h as be en used fo r do wnli nk d ata trans miss i on b y th e
fi rst b as e s t atio n a nd a gate wa y devi ce; and
t ransmission mean s fo r tran sm it tin g, t o t he gate wa y devi ce , a
25 s econ d si gnal t o r equ est th e gat ew ay de vice to u pdat e t he t ranspo r t
i nformat ion , t he secon d si gnal i nclu din g t he trans port in format i on. (S up pl eme nta r y no te 7)
The base st at ion ac co rdin g to Supp lemen tary not e 6, wh erei n the
t r an smission m e an s t r ansm its, to th e gat ew ay d ev ic e, th e seco nd s i gnal
30 i nclu din g confi gurat i on in fo r matio n to d i s abl e s etti ng o f the t r anspo rt
i nformat ion . (S up pl eme nta r y no te 8)
The base st at ion ac co rdin g to Supp lemen tary not e 6 or 7, wherein t he r eceptio n me an s r ec ei ves th e fi rst si gnal v ia t he gat ew a y

28 devi ce. (S up pl eme nta r y no te 9)
A gateway device comprisin g:
r eceptio n m ean s f or r eceivin g, when a ha ndover of a t ermin al
5 commu nic ati ng with a fi rst b as e st at ion occu rs, a s eco nd s i gnal f or
r equest ing t o upd ate t ranspo rt i nformati on, t he se cond si gnal b ein g
t r ansmitt ed from a se cond b ase stati on a nd in clu di ng th e t r ansport
i nformat ion wh ich h as b een used for do wnlin k d ata trans mi ssio n b y t he
first base station and the gateway device ; and
10 hand ove r m eans fo r handi ng ov er t he t rans port i nfo rm atio n to a
commu nic ati on with t he se cond b ase st ati on . (S up pl eme nta r y no te 10 )
The gateway device according to Supplementary note 9, wherein
t he r ecep tion me a ns r ec ei ves th e se cond si gnal in clu din g confi gurat io n
15 i nformat ion to d is abl e settin g of t he t r anspo r t info rm atio n, the s econ d
si gn al b ein g t ransmit t ed from t he s econd bas e sta ti on. (S up pl eme nta r y no te 11)
The gateway device according to Supplementary note 9 or 10,
f urt her comp ri si ng t ransmi ssion m ea ns for tra nsmi ttin g, to t he se co nd
20 bas e s tat ion, a first si gnal incl udin g the trans port in fo r mati on r ec eiv ed
b y t he r ec eption m ea ns f ro m th e first b ase sta t i on . (S up pl eme nta r y no te 12)
A m eth od for con troll ing a b ase st ati on , co mpris ing:
t ransmitt ing, wh en a handov er o ccurs du ri ng c ommu ni cat ion wit h
25 a t ermi nal , a first si gnal to a s eco nd b as e st atio n, t he firs t s i gnal
r equest in g t he se con d b ase sta ti on t o st art the han dover an d in clud ing t r anspo rt i nform atio n which ha s been use d fo r dow nl ink dat a
t r ansmission b y t he b ase s ta ti on and a gateway d ev i ce , the b as e s tati on
and th e ga te wa y d evi ce being co nn ected to a n u pp er network so t hat
30 t he y are ab l e to c ommu nicate wit h each ot he r.
(S up pl eme nta r y no te 13)
The m et hod fo r co ntroll in g a b ase st atio n a cco r di ng to S uppl eme nta r y no te 1 2, wher ein the fi r st si gn a l is t r ansmitt ed to th e s econ d base stat ion via th e ga te wa y devi ce.

29 (S up pl eme nt ary n o te 14)
A m eth od for con troll ing a b ase st ati on , co mpris ing:
r ecei vin g, when a han dover o f a t ermin al com muni ca t i ng w ith a
fi rst b as e s t at ion o cc urs, a first si gna l f or re que st ing t o st art th e
5 hand over , th e fir st si gn al in cl u di ng tra nspo rt in f orm ati on whi ch has
be en us ed fo r do wnli nk d ata transmi ssion b y t he first b as e st atio n and a gateway device; and
t ransmitt ing, to th e gat ew a y de vice, a s eco nd s ign al to re que st
t he gate wa y devi ce t o update the t r ans port i nf orm ati on , the s eco nd
10 si gn al in clud ing t h e t ranspo r t i nformat ion .
(S up pl eme nta r y no te 15)
The m et hod fo r co ntroll in g a b ase st atio n a cco r di ng to
S uppl eme nta r y no te 1 4, wher ein the s eco nd si gna l i ncl udin g
confi gurat ion in fo rm ation to disab le se tt i ng o f t he tran sp ort
15 i nformat ion is tran smi tt ed t o th e ga te wa y d ev i ce.
(S up pl eme nta r y no te 16)
The m et hod fo r co ntroll in g a b ase st atio n a cco r di ng to
S uppl eme nta r y no te 1 4 o r 1 5, wh erein th e fi rst si gna l i s re ce i ved v ia
the gateway device.
20 (Supplementary note 17)
A m eth od for con troll ing a ga te wa y dev ic e, com pri si ng:
r ecei vin g, when a han dover o f a t ermin al com muni ca t i ng w ith a
fi r st bas e s tat ion oc cu rs, a se co nd sign al for r eq ues ti ng to upd at e
t r anspo rt i nfo rmat ion, t he se co nd si gnal b ein g t ransmi tted fro m a
25 s econ d base stat ion a nd in cludi ng the t r anspo r t info rmat ion whi ch has
be en us ed fo r do wnli nk d ata transm iss io n b y t he first b as e st atio n an d t he gate wa y devi ce ; and
handi ng o ver the trans por t information to a com municatio n with
t he se cond b ase s tat ion .
30 (Supplementary note 18)
The m et hod fo r co ntro ll in g a ga te wa y devi ce ac cordin g to S uppl eme nta r y no te 1 7, wher ein the secon d si gnal i ncl uding confi gurat ion in fo rm ation to disab le se tt i ng o f t he tran sp ort i nfo rm at ion i s recei ve d from t he s econd b ase st ati on .

30 (S up pl eme nta r y no te 19)
The m et hod fo r co ntr oll i ng a ga te way devi ce ac cordin g to
S uppl em entar y n ot e 1 7 or 18 , wh erei n th e first si gna l in cl udin g th e
t r anspo rt i nfo rmat ion receiv ed f rom th e f irst ba s e station is
5 t r ansmitt ed to th e se cond b as e st atio n .
(S up pl eme nta r y no te 20 )
A n on - t ransito r y com put e r r ead abl e me dium fo r c ausin g a compu ter to ex ecute a me thod fo r c ontroll in g a b ase stat io n , the m etho d c om prisin g: t r ans mitti ng, wh en a h an do ver o cc urs du ri ng
10 commu nic ati on with a t ermin al, a first s i gnal to a seco nd b as e st atio n,
t he first s i gnal r eq ues t i ng t he se co nd b ase sta t i on to s ta rt th e h an dov er and i nclu din g t ranspo rt i nformat ion which has b een use d f or d own link data t r ansmiss ion b y t he ba s e statio n and a gat ew ay d e vic e , th e b ase st at ion and th e gat ew a y d ev ic e bein g co nn ected to a n u pper net wo rk so
15 t hat th e y a r e abl e to co mmun ic at e wi th each ot he r .
(S up pl eme nta r y no te 21)
The non -t ransit or y comp ute r r ead abl e me di um for causin g a compu ter to ex ecute t he m eth od for con t ro llin g a base st at ion ac cordin g t o Supp lem en t ary not e 20, wh ere i n th e fi rst s i gn al is
20 t r ansmitt ed to th e se co nd b as e s t atio n via t he gat ew a y d evice.
(S up pl eme nta r y no te 22)
A n on - t ransito r y com put er r ead abl e me dium fo r c ausin g a compu ter to ex ecute a me thod fo r c ontroll in g a b ase stat io n , the method comprising:
25 receiving, when a han dover of a terminal communicating with a
fi r st bas e s tat ion oc cu rs , a fi r st sign al for re que st ing t o st art th e hand over , th e fir st si gn al in cl u di ng tra nspo rt in f orm ati on wh i ch h as be en us ed fo r do wnli nk d ata transmi ssion b y t he first b as e st atio n and a ga t e wa y de vi ce; and
30 t ransmitt ing, to th e gat ew a y de vice, a s eco nd s ign al to re que st
t he gate wa y devi ce t o update the t r ans port i nf orm ati on , the s eco nd si gn al in clud ing th e t ranspo r t i nformat ion . (S up pl eme nta r y no te 23)
The non -t ransit or y comp ute r r ead abl e m edi um fo r ca us in g a

31
compu ter to ex ecute t he m eth od for con t ro llin g a base st at ion
ac cordin g t o S uppl eme nt ar y n ote 22, wher ei n th e s ec on d sign al
i nclu din g confi gurat i on in fo r matio n to d is able sett i ng o f th e t ransp ort
i nformat ion is tran smi tt ed t o the ga te wa y d ev i ce.
5 (Supplementary note 24)
The non -t ransit or y comp ute r r ead abl e me di um for c aus ing a compu ter to ex ecute t he m eth od for con t ro llin g a base st at ion ac cordin g t o Supp lem ent ary not e 22 o r 23 , whe r ein th e first si gnal is r ecei ved via t he gat ew a y d evice .
10 (Supplementary note 25)
A n on - t ransito r y com put er r ead abl e me dium fo r c ausin g a compu ter to ex ecute a me thod fo r c ontroll in g a gatewa y d evi ce , th e method comprising:
r ecei vin g, when a han dover o f a t ermin al com muni ca t i ng w ith a
15 fi rst b as e s t at ion o cc u rs, a s eco nd si gnal f or r eq ues ti ng to upd at e
t r anspo rt i nfo rmat ion, t he se co nd si gnal b ein g t ransmi tted fro m a s econ d base stat ion a nd in cludi ng the t r ansport info rmat ion whi ch has be en us ed fo r do wnli nk d ata tr an smi ssio n b y t he first b ase st atio n and t he gateway d ev i ce; and
20 handi ng o ver the t r anspo r t info rm ati on to a com municatio n with
t he se cond b ase s tat ion . (S up pl eme nta r y no te 26)
The non -t ransit or y comp ute r r ead abl e me di um for c aus ing a compu ter to ex ecute t he m eth od for con t ro llin g a gat ew a y dev ice
25 ac cordin g t o Supp lem en t ary not e 25, wh ere i n th e s ec on d sign al
i nclu din g confi gurat i on in fo r matio n to d is able sett i ng o f th e t ransp ort i nfo rmat ion i s receiv ed from th e s ec ond bas e st atio n . (S up pl eme nta r y no te 27)
The non -t ransit or y comp ute r r ead abl e me di um for c aus ing a
30 compu ter to ex ecute t he m eth od for con t ro llin g a gat ew a y dev ice
ac cordin g t o Supp lem en t ary not e 25 o r 26 , whe r ein wh en th e fi r st si gn al in clud ing th e tra ns port i nfo rmat ion i s re ceiv ed f r om t he fi rst bas e s tat ion, the fi rs t s ign al i s t r ansmit ted t o t he se co nd base st at ion . [ 0094]

32
Whil e the present in venti on h as b een d esc rib ed a bov e with
r eferenc e t o ex empl ar y emb odim en ts, the pre se nt i nv entio n i s n ot
l i m ited to t he ab ov e exem pla r y emb odim ent s . Th e con fi gura ti on and
details of t he p r es ent inv e nti on can b e mo difi ed i n var ious ways whi ch
5 ca n b e un derst ood b y t hose ski l l ed i n th e art wit hin the s cop e o f t he
i nven tion . [ 0095]
This appli cati on is based upo n and clai ms th e be ne fit o f p r iorit y
f r om Japan ese pate nt appl icatio n No. 201 3 -12 289 5, fil ed on J un e 11,
10 2013, th e dis clo su r e of whi ch is i nco r pora t ed h er ei n in its entiret y b y
r eferenc e.
Reference Signs List
[ 0096]
15 100 HNB
101 CELL
102 CELL
103 HNB
104 TERMINAL
20 105 HNB-GW
106 Iurh In te r f ace
200 RADIO COMMUNICATION PROCESSING MEANS
201 INTER-HNB MESSAGE PROCESSING MEANS
202 HNB-GW COMMUNICATION MEANS
25 203 DATABASE MEANS
300 HANDOVER MEANS
301 HNB COMMUNICATION MEANS
302 DATABASE MEANS
1000 COMMUNICATION SYSTEM

WE CLAIM:
1. A communication system comprising:
a terminal;
5 a first base station to which the terminal is connected before
movement;
a second base station to which the terminal is connected after movement; and
a gateway device that connects the first base station and the
second base station to an upper net work so that they are able to
communicate with each other, wherein
the first base station transmits, to the second base station , a
first signal to request the second base station to start a handover, the
first signal including transport information which has been used for
data downlink data transmission by the gateway device and the first
base station communicating with the gateway device during a handover of the terminal ,
the second base station receives the first signal and transmits, to
the gateway device, a second signal to request the gateway device to
update the transport information , the second signal including the
transport information, and
the gateway de vice receives the second signal and hands over the transport information of the first base station to a communication with the second base station .
2. The communication system according to Claim 1, wherein the
second base stat ion transmits, to the gateway device, the second signal
including configuration information to disable setting of the transport
information . 30
3. The communication system according to Claim 1 or 2,
wherein t he first base station transmits the first signal to the second
base station via the gateway device.

4. A base station comprising:
transmission means for transmitting , when a handover occurs
during communication with a terminal , a first signal to a second base
station , the first signal requesting the second base station to start the
handover and including transport information which has been used for
downlink data transmission by the base station and the gateway device.
5. A base station comprising:
reception means for receiving , when a handover of a terminal
communicating with a first base station occurs, a first signal for
requesting to start the handover, the first signal including transport
information which has been used for downlink data transmission by the
first base station and a gateway device ; and
transmission means for transmitting, to the gateway device , a second signal to request the gateway device to update the transport information , the second signal including the transport information.
6. The base station according to Claim 5, wherein the
transmission means transmits, to the gateway device , a second signal
20 including configuration information to disable setting of the transport
information .
7. A gateway device comprising:
reception means for receiving , when a handover of a terminal
communicating with a first base station occurs, a second signal for
requesting to update transport information, the second signal being
transmitted from a second base station and including the transport
information which has been used for downlink data trans mission by th e
first base station and the gateway device; and
handover means for handing over the transport information to a
communication with the second base s tati on.
8. The gateway device according to Claim 7 , wherein the
reception means receives the second signal including configuration

information to disable setting of the transport info rmation , the second signal being transmitted from the second base station .
9. A method for controlling a base station, comprising:
receiving, when a handover of a terminal communication with a
first base station occurs, a first signal for requesting to start the
handover , the first signal including transport information which has
been used for downlink data transmission by the first base station and
a gateway device; and
transmitting, to the gateway device, a second signal to request
the gate way device to update the transport information , the second signal including the transport information .
10. A method for controlling a gateway device , comprising:
receiving, when a handover of a terminal communicating with a
first base station occurs, a second signal for requesting to update
transport information, the second signal being transmitted from a
second base station and including the transport information which has
been used for downlink data transmission by the first base station and
20 the gateway device; and
handi ng over the trans port information to a communication with the second base station .