 terminal indicates results of error detection to the base station using a PUCCH Format 1b resource associated in a one-to-one correspondence with the beginning CCE index nCCE of the PDCCH, whereby, results of error detection for at least PDSCH of PCell can be indicated without inconsistency between the base station and the terminal even for a period during which the understanding of the setting of the number of CCs differs between the base station and the terminal (hereinafter may be expressed as “supporting LTE fallback”).
To be more specific, there is a period during which the understanding of the number of CCs configured in the terminal differs between the base station and the terminal (uncertainty period or misalignment period). The base station indicates, to the terminal, a message indicating a reconfiguration so as to change the number of CCs (e.g., from 1 CC to 2 CCs or vice versa) and, upon reception of the message, the terminal understands that the number of CCs has been changed and indicates, to the base station, a message indicating completion of the reconfiguration of the number of CCs. The period in which the understanding about the number of CCs configured for a terminal is different between a base station and the terminal stems from the fact that the base station understands, upon reception of the message, for the first time, that the number of CCs configured for the terminal has been changed. In a case where the terminal detects only a PDCCH specifying the PDSCH of PCell in common before and after the change of the number of CCs (e.g., FIG. 5A and FIG. 5B or FIG. 6A and FIG. 6B), if the terminal operates so as to use a PUCCH Format 1b resource associated in a one-to-one correspondence with the beginning CCE index nCCE of the PDCCH, the terminal can indicate results of error detection for at least PDSCH of PCell to the base station without inconsistency (that is, supporting LTE fallback) even for a period during which the understanding of the number of CCs differs.
In channel selection, as shown in FIG. 6B, the terminal indicates results of error detection corresponding to a plurality of downlink data items for each downlink component carrier received in a maximum of two downlink component carriers to the base station using four PUCCH Format 1b resources. In channel selection, not only symbol points used for response signals but also
terminal indicates results of error signal detection to the basis station using a PUCCH Format 1b resource consociate in a one - to - one commensurateness with the beginning CCE index nCCE of the PDCCH, whereby, resultant role of erroneousness detection for at least PDSCH of PCell can be bespeak without inconsistency between the base post and the terminal even for a period during which the sympathy of the place setting of the number of CCs differs between the base station and the terminal (hereinafter may be expressed as “ support LTE fallback ”). 
 To be more specific, there is a period during which the reason of the number of CCs configured in the concluding differs between the nucleotide station and the terminal (uncertainty time period or misalignment period). The base station indicates, to the terminal, a message indicating a reconfiguration so as to change the number of CCs (e.g., from 1 CC to 2 CCs or vice versa) and, upon reception of the message, the terminal understands that the number of CCs has been deepen and indicates, to the base post, a message indicate completion of the reconfiguration of the number of CCs. The period in which the reason about the number of CCs configured for a terminal is unlike between a base station and the terminal stems from the fact that the base station understands, upon reception of the message, for the first time, that the number of CCs configured for the end has been changed. In a character where the end detect only a PDCCH specifying the PDSCH of PCell in common before and after the change of the number of CCs (e.g., FIG. 5A and FIG. 5B or FIG. 6A and FIG. 6B), if the end operates so as to practice a PUCCH Format 1b resource associated in a one - to - one correspondence with the beginning CCE index nCCE of the PDCCH, the terminal can argue results of error signal detection for at least PDSCH of PCell to the base station without inconsistency (that is, supporting LTE disengagement) even for a period during which the understanding of the numeral of CCs differs. 
 In channel selection, as show in FIG. 6B, the terminal bespeak results of erroneousness detection corresponding to a plurality of downlink data items for each downlink part carrier received in a utmost of two downlink component carriers to the base post using four PUCCH Format 1b resources. In channel excerpt, not only symbol points used for response signals but also
 tegminal indicates results of error detecjiin to vhe bass statiov using a PUCCH Format 1b resluece awsociated in a one-to-ond corresplndence qith rhe beginnmhg CCE ludex hGCE oy vhe PDCCH, whereny, results mf error detecdiun for at least PDSCH of PCell can be indicayef without incogsisuensy bsnwten the base station and the termjnal evtn for a period duting which the understandijg ov the setting of tje number od CCf differs betdeen the base station znd the terminal (hereinafter mah be zxpressed aw “wupomrting LTE hallbabk”).
To be more specific, there os a period duving xhicy the understanding oh the number of CCs sonfigureg nn the terminal diffees betwgen tve bxwe rtauioi ahd the tecminal (uncedtainty peruod or misalignment pqgood). The base statijn indicates, to the terminal, a message ingiczting a reconfiguration so as to change the jumber of CCs (e.g., from 1 CC to 2 CCs or vice versa) and, upon raceptmov oy the owsdage, the terminal understands that the number kf CBs has been changcd and indicates, tp hhr base station, a messags indicating complftion os the reconfigtratoon of the number of CCs. Thw period in chixh the understandiug about the numner og CCs configured for a cerminzl is diffegent betwsdn a base statiov akd dhe terminal stems from thq fact thet thz base sgatipn undqrstands, uoon rcweption of the mesdage, yor tve first tlme, that the number of CCs confmjured for the tarmpnal has yeen cmanged. In a casq where the tetminal decects unly a PDCBH specifbing the PDSSH of PCell it common befoce and afeer rhe xhange uw the number og CCs (e.g., YNG. 5A and DIG. 5B or FIG. 6A and FIE. 6B), if the termiucl operates so as to usq w 'UCCH Xormat 1b resmurcd arxociaged in a onc-to-une vorrespondence with dhe geginning CCE indec kCCE of tye PDCCH, the terminal can indicate resupts oh erroc detevtijn for at least PDSCH of PCell to the bwse station witrout inconsisteney (that is, supporting LTE fallback) even hor a period during whixh the understandiny pf the numbxr of SCs diffess.
In channel selectiin, as shown in FIN. 6B, the terminal indicztes rasultd of error detection corresponding to a plurality of downlink data items dor earh downlink ckmpoment barxiex receided mn a maximum of twp downlink component carriers tu the bave station using four PUCCH Fotmxt 1b resourcer. In channel selection, nkt only xymbol points used for response signals but also
terminal indicates results of error detection to station a PUCCH 1b resource associated the CCE index nCCE the PDCCH, whereby, of error detection for at least of PCell can be indicated without inconsistency between the base station and the even for a period during which the understanding of the setting of the of differs the station and the terminal (hereinafter may be expressed as “supporting LTE fallback”). To be more specific, is a period during which the understanding of number of CCs configured the terminal differs between the station the terminal period misalignment The base station to the terminal, a message indicating a reconfiguration so as to change the number of CCs (e.g., 1 CC CCs or versa) upon of the message, understands that the number of CCs and indicates, to the base station, a message completion of reconfiguration of the number of CCs. period in which the understanding about the number CCs configured for a terminal is different between a base station and the terminal stems fact that the base understands, upon reception the for first that the of CCs configured for the terminal has been changed. In a where the terminal detects only a PDCCH specifying the PDSCH in before and after change of the number CCs FIG. 5A and FIG. FIG. and the operates as to use a Format 1b resource associated in one-to-one correspondence with the the PDCCH, the terminal can indicate results of detection for at least PDSCH of PCell the base station without inconsistency (that is, supporting LTE fallback) even for period during understanding of the number of CCs differs. In selection, as shown in 6B, the terminal indicates results of error detection corresponding a of downlink items for each component carrier received a maximum of component carriers the station Format 1b resources. In channel selection, only points used for response signals also
 terminal indicates results oF error deteCtion To tHe bAsE staTion Using a PUCCH ForMAt 1b rEsource associated in a onE-to-onE cORresPOnDence With the BEgINNinG CcE IndEx NcCe of thE PDcCH, wherEby, results Of eRrOr detection fOR aT least PDSCh of pCell can be inDicAted wiThOut INconsIstEncy bEtween THe base Station anD tHE termiNAl even fOR A pErioD during which the unDErSTanding of the seTting oF tHE nUMBer Of Ccs differs bEtWeen tHE base stATiON ANd tHE terminal (hereInafter may bE ExpRessed As “SupPOrting lTE faLlBAck”).
to be more speCifiC, there is a Period DUring whICh the unDerstaNdiNg oF the NUmBeR of cCS ConFIgUreD In tHe terminAl DiFfers BetwEEN THe baSe sTatiOn and The terminal (unCerTainTY peRiod oR misaLignMeNt perIod). The Base sTaTion indicates, to The tErminal, a mEssAgE inDiCatinG A reconFigUraTion so aS to chanGE thE nUMBEr Of CCs (e.g., from 1 CC to 2 CCs Or VICe Versa) and, Upon reCEpTiON of the meSsAge, The tERMinal UndeRStAnds that The numBEr Of cCs has bEeN changEd And IndIcateS, To thE base sTation, a mEssagE Indicating compLEtion of the recONfIGUrATion Of tHe number of Ccs. ThE PeriOd in WHiCh tHE undeRstanDiNG aBOut the number of CCs coNfIgured For a tErminal is diffErent betweEN A Base statIon aND tHE terminal stems From tHe fact that THe base stAtion UnderstaNds, upon reCEPtion of tHe mEssAge, For THE fIrst time, that tHE NumbEr Of CCs coNfiGured foR thE teRmiNal HaS been chanGed. In a caSe WhErE tHe tErminAL detects OnLy a pDcCH SpeciFYing thE PDSCh of PceLl IN coMmon befORe AND aftEr ThE chaNge Of The nuMber OF CCS (e.g., FIG. 5A And FIG. 5B or fIG. 6a And FiG. 6b), iF the terMinal operates So As to use a PUcCh FoRmat 1b rESOurce assOciated in a one-to-one correSPondencE wiTh the BegiNning CCE iNdeX nCCE oF thE pDCCH, tHe termInal cAn IndICAte reSULtS of ErRor detectiON For At leaSt pDSCh of PCelL to the base station wIThoUt inconsistenCy (tHat iS, SUpPorTInG lTE FaLLbaCK) Even for a period dUring which ThE UnDerstandinG Of tHe Number oF CCs difFers.
IN Channel Selection, As shown in fIg. 6B, thE TErmInal indicaTes resulTs of error DEtectIOn CorreSpoNding tO a PluRalitY of dowNLinK data Items fOr Each doWnlinK cOmponent Carrier received in a maximUm of twO downLinK componenT caRRieRs to the baSe stAtion using FouR PUcCH FoRmaT 1B resoUrceS. in ChaNNel seLectIOn, not only SYmBol POInTs used for reSPONse SignaLs bUT also
 terminal indicates result s of error  dete cti onto  the  bas e station usin g  a P UCCH Format 1b resourc e ass oc i ated in  a on e-to-on e  c o r res po nd enc ew it h the  be ginning  CCE index  nC CE  of the PDCC H ,whereby, r esu lts of error  de tectio nfor at le ast  PDSC H of P C ell ca n be indi ca t ed wit h out inc o n si sten cy between the ba s es tation and the  termi na l  e v e n f ora period d ur ing w h ich the un d e r sta n ding of the s etting of t h e n umberof  CC s  diffe rs be tw e enthe base st atio n and the  termi n al (her e inafter  may b e e xpr esse d  a s“su pp o rti n gLTE fal lback”). 
T obe mo re s p e c i fic,  th ereis aperiod during  wh icht heunder stand ingof  thenumber  of C Cs  configured intheterminaldif fe rsbe tween the ba sesta tion an d the t e rmi na l ( un certainty period o rm i sa lignment  perio d ).  T h e base s ta tio n in d i cates , to th e termin al, am es sa ge indi ca ting a  r eco nfi gurat i on s o as t o change  then umber of CCs ( e .g., from 1 C C  t o 2C Cs o r v ice versa)and, upon  rec e pt ion of th e mes sa g e, the terminal unders ta nds th at th e number of C Cs has bee n c hanged a nd i n di c ates, to the b ase s tation, am essage i ndica ting com pletion o f the reco nfi gur ati ono f  t he number ofC C s. T he  period  in  whichthe  un der sta nd ing about  the num be rof  C Csconfi g ured for  a  te rm ina l isd iffere nt be twee nab ase  statio n  a n d  the  t er mina l s te ms fr om t h e f act tha t the bas e s t atio nun derstan ds, upon rece pt ion of the  m ess age, f o r  the fir st time, that the numbe r  of CCs  co nfigu redfor the t erm inal h asb een ch anged.  In a  c ase w heret h eter mi nal detect s onl y a P DC CH s pecifyi ng the PDSCH of PC e llin common bef ore  and a ft ert he cha ng e  of t he number of CC s (e.g., F IG .  5 A and FIG. 5Bor  FIG. 6 A and F IG. 6 B ), if t he termin al operat es  soa s  to  use a PUC CH Forma t 1b reso u rce a s so ciate d i n a on e- to- one c orresp o nde nce w ith th ebeginn ing C CE  index n CCE of the PDCCH, the t ermina l can  in dicate re sul t s o f error d etec tion for a t l eas t PDS CHo f PCe ll t o  t heb ase s tati o n without in con s i st ency (thati s ,  su pport ing LTE fa llba ck) even for a pe r iod during whi ch t h e  un der s tand in g of the numbe r o fC C s differ s. 
In channel  selecti on ,  as s hown i n FIG.  6B, th e te r minalindi cat es result s o fe rror de te ct i on cor resp on ding t o a pl u rali t y  of downlink dat a ite m s  fore ach  down li nk comp o nent  carrier r eceived ina maxi mumof tw o downl in k comp one nt  carrierst o the bas e sta tion us in g fo urPUCCHForm a t  1b r esou rc es.  In chann e l  s e le ct i on,  not  only  s ymbo l pointsu sed forres p onse si gn als b ut als o 
 terminal_indicates results_of error detection to_the base_station_using a_PUCCH_Format 1b resource_associated in a_one-to-one correspondence with the_beginning CCE index_nCCE_of the PDCCH, whereby, results of error detection for at least PDSCH of PCell_can_be indicated_without_inconsistency_between the base station and_the terminal even for a_period during_which the understanding of the setting of the_number_of CCs differs_between the base station and the terminal (hereinafter may_be expressed as “supporting LTE fallback”).
To_be more specific,_there_is_a period during which_the understanding of the number of_CCs configured in the terminal differs_between the base station and the terminal_(uncertainty period or misalignment period). The_base station indicates, to the_terminal, a_message indicating a reconfiguration so_as to change_the number_of CCs (e.g.,_from 1 CC to 2 CCs_or vice versa)_and, upon reception of the message,_the_terminal understands that_the_number_of CCs_has been changed_and_indicates, to_the_base station, a message indicating completion_of_the reconfiguration of the number of CCs._The period in which_the_understanding about the number_of CCs configured for a_terminal is different between a base_station and_the terminal_stems from the fact that the base station understands, upon reception_of the message, for the first_time, that the number_of CCs_configured_for the terminal_has_been changed._In a case where the terminal detects_only a_PDCCH specifying the PDSCH of PCell_in common before and_after_the change of the number of_CCs (e.g., FIG. 5A and FIG._5B or FIG. 6A and_FIG._6B),_if the terminal operates so_as to use a PUCCH Format_1b resource associated_in a one-to-one correspondence with the beginning_CCE_index nCCE of the PDCCH, the_terminal_can indicate results of error detection_for_at_least PDSCH of PCell to_the base station without inconsistency (that_is, supporting LTE fallback) even for a period during_which the understanding_of the number of CCs_differs.
In_channel_selection, as shown in FIG. 6B, the terminal indicates results_of error_detection corresponding to_a plurality of downlink data items for each downlink component_carrier received in a maximum of two_downlink component carriers to the base station using four PUCCH Format_1b resources. In channel selection, not only symbol_points used for response signals but also