1. A radio communication system comprising: a fi rst ra dio s tat ion that se r ves a fi rs t cell; 5 a seco nd radio st atio n th at s erv es a s ec on d cell; an d a radio t ermin al c ap able o f p erformi ng c arri er a ggr egatio n o f th e fi rst and s eco nd c ells, wher ein t he first radio st ation is c onfigu red t o perform , with th e rad i o t ermin al, r ad io resou rce cont ro l fo r th e fi rst a nd s eco nd c ells in orde r 10 t o p erfo rm t he car ri er aggre ga tion , and at l eas t one o f th e seco nd ra di o st ati on and t he ra dio te rm inal is confi gure d to t ran smi t , to t he fi rst radi o st ati on , in fo r matio n abo ut a r adio li nk p robl em o cc urri ng in a rad io l ink in the s econd cell b etw ee n t he s econd r ad io sta t i on and th e radi o te rmin al whi le t he c arrier 15 aggre gat ion is bein g pe rfo rmed .

2. The radio communication system according to Claim 1, wherein th e i nforma ti o n abou t the ra di o link problem incl ud es at l east one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id ent if ie r , a 20 be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n.

3. The radio communication system according to Claim 1 or 2, 25 wherein th e probl em i nclud es at leas t on e of radio l i nk di s con necti on, call d is con nection , a l oss of s ync hronization , re ce i ved qua lit y de gradat ion , and t hrou gh put d egrad atio n .

4. The radio communication s ystem according to any one of 30 Cl ai ms 1 t o 3 , whe r ei n th e info rmation about t he rad io li nk p r oblem i ndicat es t hat th e p robl em is l ikel y t o oc cur or th at t he p rob lem h ad oc cu rr ed but has b ee n re co vered .

5. The radio communication system according to Claim 4, 41 wherein th e at least one o f t he s econd ra di o s tati on an d th e radio t ermin al d et ermin es that th e p ro bl em is li kel y to o ccu r b as ed on a m ovin g sp ee d o f th e r adi o t ermin al or an estim ati on result o f th e moving speed. 5

6. The radio communication system acc ording to any one of Cl ai ms 1 t o 5 , whe r ei n th e r adi o t ermin al det ects t he prob lem an d t r ansmits the i nforma t i on abou t th e ra dio link problem to th e f i rst r adio sta ti on. 10

7. The radio communication system according to any one of Cl ai ms 1 t o 6 , whe r ei n th e ra di o term inal d etects t he p r obl em and t r ansmits t o t he fi rst rad io s t atio n a r equest fo r re con fi gura tion o f th e s econ d ce ll i ncl udin g th e in f orm ati on a bou t th e r adi o l ink p r oblem . 15

8. The radio communication system according to any one of Cl ai ms 1 t o 5 , wherei n th e secon d r adio sta tion d ete cts t he p r obl em and t r ansmits the i nforma t i on abou t th e ra dio link problem to th e f i rst r adio sta ti on. 20

9. The radio communication system according to any one of Cl ai ms 1 t o 8 , whe r ei n th e f irs t radio st ati on is c onfi gu r ed to re cei ve t he in fo r matio n ab out the ra di o link problem an d to c ont r ol commu nic ati on of the rad io te r m i nal in th e secon d c ell . 25

10. The radio communication system according to any one of Cl ai ms 1 t o 9 , whe r ei n th e info rmation about t he rad io li nk p r ob lem t r i ggers t he first radi o st ati on to p erform cont r ol to cope wit h the problem. 30

11. The radio communication system according to Claim 10, wherein th e con trol to cope wit h t he p ro bl em p erform ed b y th e fi rst r adio sta ti on in clu des at le ast one of : con trol to r ecov er t he ra di o lin k of th e ra di o termi nal in th e se cond cell ; con trol to r el eas e th e ra di o 42 l i nk of th e radio t erm inal in th e sec ond cell, or c ontrol to es tab li sh a r adio li nk o f the r adi o t ermin al in a cel l d iff ere nt from th e secon d ce ll .

12. A fi rst r adi o stat ion t hat se r ve s a fi rs t cell , comp r is i ng: 5 commu nic ati on co ntrol means for su ppo rt ing car r ie r aggrega ti on o f the first c el l an d a s eco nd c ell s erv ed b y a secon d ra di o st ati on, wherein t he co mmun i cat ion control m ea ns p erfo rms , wit h a r adi o t ermin al, r ad io resou rce cont ro l fo r t he firs t and secon d ce l l s in orde r 10 t o p erfo rm t he car ri er aggre ga tion i n th e radio t erm inal, an d t he co mmun i cat ion control m ea ns recei ve s , from at l ea s t one o f t he s econd r ad io sta t i on and th e radi o te rmin al , at le as t on e o f: i nformat ion ab out a rad i o l ink p r oblem oc curring in a radio li nk in th e s econ d ce ll b etween the second r adio st atio n and th e radi o te rm in al 15 while t he car ri er aggre ga tion i s bei ng per fo r med ; and radio li nk st atu s i nformat ion ind icatin g t hat t he pr ob lem has b een det ected in th e radio link.

13. Th e f irs t radio st ati on a cc ordin g to Claim 12 , w herei n th e 20 i nformat ion ab out the r adio lin k pro blem i ncl udes at l ea st on e of t r i gger i nformati on, a t erm inal id ent ifi er, a c ell identi fi er, a beare r i dent if ie r , a dat a tra ns m i ssio n/re cept ion sta tu s , ra dio qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n. 25

14. Th e f irs t radio st ati on a cc ordin g to Claim 12 o r 13 , w he r ein t he pro blem in clu de s at l east o ne of r ad i o li nk di s con nect ion , c all di s con ne cti o n, a l os s of s yn ch r onization , re ce i ved q ual it y d egra da t ion , and th r ough put degrada tion . 30

15. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o 14, wher ein th e info rm at ion abo ut t he r adio lin k pro bl em in dicat es t hat t he pro blem is lik el y to o cc ur or t ha t t he p ro blem h ad o ccurre d b ut ha s be en recover ed . 43

16. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o 15, wher ein th e co mmun i cati on c ontrol m ea ns recei ve s from th e radio t ermin al a requ es t f or re confi gurat ion of th e secon d cell i ncl uding t he 5 i nformat ion ab out the r adio lin k pro blem .

17. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o 16, wher ein th e co mmun i cati on c ontrol m ea ns recei ve s the i nformat ion about t he radio l ink prob lem and con t rol s co mmuni cat ion of th e rad i o 10 t ermin al i n t he se cond cell .

18. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o 17, wher ein th e info rm at ion abo ut t he r adio lin k pro bl em tri ggers th e fi rst rad io st ati on to p erform con t ro l t o co pe w i th th e prob lem . 15

19. Th e f irs t radio st ati on a cc ordin g to Claim 18 , w herei n th e cont ro l to cope with t he p r ob lem p erformed b y t he fi r s t r adio sta ti on i nclu des at least o ne of : con t ro l to r ecov er t he r ad io li nk of the r adio t ermin al in th e s ec ond cell ; co ntrol t o r eleas e t he r ad io lin k of t he 20 r adio t erminal in th e secon d ce ll ; or c on trol to e stablish a ra dio link of t he rad io t e rmi nal in a cell di fferent from th e s ec ond cell.

20. A s eco nd radi o s tatio n tha t se r ve s a se cond cel l , comp ri si ng: commu nic ati on co nt rol me ans for su ppo rtin g ca r r i er aggr ega t ion 25 o f a fi rst cel l served b y a fi rst r adio stat ion an d th e s econ d c ell , wherein t he co mmun i cat ion control m ea ns t ransmit s , to t he first radio st at ion , i nforma tio n abou t a ra di o lin k probl em oc cu r rin g in a r adi o l i nk i n th e se cond cell b etw een t he se cond r adio s tat ion a nd a rad io 30 t ermin al while t he car ri er aggre gat i on is bei ng perfo rm ed b y th e ra di o t ermin al.

21. Th e s ec ond radio st ati on a cc ord in g t o Claim 20 , wh erei n the i nformat ion ab out the r adio lin k pro b lem i ncl udes at l ea st on e of 44 t r i gger i nformati on, a t erm inal id ent ifi er, a c ell identi fi er, a beare r i dent if ie r , a dat a tra ns m i ssio n/re cept ion sta tu s , ra dio qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm ati on. 5

22. Th e s ec ond radio st ati on a cc ord in g t o Claim 20 o r 21 , wherein th e probl em i nclud es at leas t on e of radio l i nk di s con necti on, call d is con nection , a l oss of s ync hronization , re ce i ved qua lit y de gradat ion , and t hrou gh put d egrad atio n . 10

23. Th e s ec ond ra di o st ati on acco rd in g to an y o ne of C laim s 20 t o 2 2, wh erein th e in form atio n abou t th e r adi o li nk p r oblem indi ca tes t hat th e pro bl em i s lik el y to occu r or th at th e probl em had oc curred but has b een r ecov ere d. 15

24. Th e s ec ond radio st ati on a cc ord in g t o Cl aim 23 , w he r ei n the commu nic ati on co ntrol means d et e rmin es th at t he p r oblem is l i kel y t o oc cu r base d on a mo vin g speed of t he radio t erm ina l o r a n est ima tion r esu lt of t h e m ovi ng s peed. 20

25. Th e s ec ond radio st ati on a cc ord in g t o an y o ne o f C laim s 2 0 t o 24, wh erei n th e in fo r m atio n ab out th e r adi o li nk p r oblem trigge r s t he first radio st ation to p erfo r m c ontrol t o co pe with th e prob lem. 25 26. Th e s ec ond radio st ati on a cc ord in g t o Claim 25 , wh erei n the cont ro l to cope with t he p r ob lem p erformed b y t he fi r s t radi o st ation i nclu des at least o ne of : con t ro l to r ecov er t he r ad io li nk of the r adio t ermin al in th e s ec ond cell ; co nt rol t o r eleas e t he r ad io lin k of t he r adio t erminal in th e secon d ce ll ; or c on trol to e stablish a ra dio link of 30 t he rad io t e rmi nal in a c ell di ff eren t from t he s econd c ell.

27. A r adi o t ermin al c om prisin g: commu nic ati on co ntrol means for su ppo rt ing car r ie r aggrega ti on o f a fi rst cel l served b y a fi rst r adio stat ion an d a se cond cel l s erv ed 45 b y a s ec ond rad io stat io n, wh erein t he co mmun i cat io n co ntrol mean s p erforms , wit h t he fi r st rad io st at ion , r adio r es ou rce co ntrol for th e fi rst and s econd cel ls in o r de r to pe rform t he carrie r aggr ega ti on, and 5 t he co mmun i cat ion control m ea ns t ransmit s , to t he first radio st at ion , at leas t on e o f : i n fo rm ation abo ut a rad io l ink problem oc cu rr ing i n a rad io link i n t he secon d cell b et we en t he se cond r adio st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s bei ng pe rform ed; and radio link st atu s info rm ation i ndi cat in g tha t t he 10 problem h as b e e n d ete cted i n th e radio l i nk.

28. Th e r ad i o t erm inal accordin g t o Cl aim 27, wh ere i n t he i nformat ion ab out the r adio lin k pro blem i ncl udes at l ea st on e of t r i gger i nformati on, a t erm inal id ent ifi er, a c ell identi fi er, a beare r 15 i dent if ie r , a dat a tra ns m i s sio n/ recept ion st atu s , radi o qu ali t y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n.

29. Th e r ad i o t erm inal accordin g t o Cl aim 27 o r 2 8, wherein th e 20 problem inc lu des at l east on e o f rad io lin k di s con nect ion , call di s con ne cti o n, a l os s of s yn ch r onization , re ce i ved q ual it y d egra da t ion , and th r ough put degrada tion .

30. Th e r ad i o t erm inal accordin g t o an y o ne of C lai m s 27 t o 29 , 25 wherein th e i nforma ti o n abou t the ra di o link problem indi ca tes t hat t he problem is l ikel y t o oc cur or tha t th e probl em had occu rr ed but h as be en recover ed .

31. Th e r ad i o t erm inal accordin g t o Cl aim 30, wh ere i n t he 30 commu nic ati on co ntrol means d et e rmin es th at t he p r oblem is l i kel y t o oc cu r base d on a mo vin g speed of t he radio t erm ina l o r an estim ation r esu lt of t h e m ovi ng s peed.

32. Th e r ad i o t erm inal accordin g t o an y o ne of C lai m s 27 t o 31 , 46 wherein th e comm uni cat io n co ntrol mean s t r an sm its to t he firs t r adio st at ion a req uest for r ec onfigu r ati on o f t he s econd cell i ncl uding t he i nformat ion abo ut the r adio lin k pro blem . 5 33. Th e r ad i o t erm inal accordin g t o an y o ne of C lai m s 27 t o 32 , wherein th e i nforma ti o n abou t the ra di o link problem trigge r s the fi r st r adio sta ti on t o per f or m cont rol to cope wi th t he p r obl em .

34. Th e r ad i o t erm inal ac co rdin g to C l aim 3 3, wherein th e 10 cont ro l to cope with t he p r ob lem p erformed b y t he fi r s t r adio sta ti on i nclu des at least o ne of : con t ro l to r ecov er t he r ad io li nk of the r adio t ermin al in th e s ec ond cell ; co nt rol t o r eleas e t he r ad io lin k of t he r adio t e rmin al in t he s ec ond cell ; or c on trol to e stablish a ra dio link of t he rad io t e rmi nal in a cell di fferent from th e s ec ond cell. 15

35. A com municati on c ontrol m ethod in a fi rs t r adi o st atio n th at s erv es a first c el l, t he met hod co mprisi ng: performi ng , w i t h a r adio te r min al , ra dio resou r ce co ntrol fo r th e fi rst cell a nd a se con d cell se rv ed b y a s econd ra di o s ta tion i n ord er to 20 pe rform carrier ag gregat ion o f the firs t an d secon d c el l s; and r ecei vin g, from at lea st on e o f th e secon d radio st atio n and t he r adi o t ermin al , at least one o f: i nformati on a bout a r adio lin k prob l em oc cu rr ing i n a rad io link i n t he secon d cell b et we en t he se cond r adio st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s b ein g 25 pe rform ed ; and r adio li nk st atu s in f orm atio n i n di cat in g tha t t he problem h as b ee n d ete cted i n th e radio l i nk.

36. The communication control method according to Claim 35, wherein th e i nforma ti o n abou t the ra di o link problem incl ud es at l ea st 30 one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id entifi er, a be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n. 47

37. The communication control method according to Claim 35 or 36, wher ein th e p robl em i ncl ud es at least one o f ra dio link di s con ne cti o n, call disco nn ecti on, a lo ss of s yn ch r oniz atio n , receiv ed quali t y d egrad at ion , and th ro ugh put d egra datio n . 5

38. The communication control method according to any one of Cl ai ms 3 5 t o 37, w he r ei n th e in fo rm atio n abo ut th e r adi o li nk p ro bl em i ndicat es t hat th e p robl em is l ikel y t o oc cur or th at t he p rob lem h ad oc cu rr ed but has b ee n re co vered . 10

39. The communication control method according to any one of Cl ai ms 3 5 t o 38, fu rt her com pris i ng p erformin g c ont rol to c op e wit h t he pro blem .

40. The communication control method according to Claim 39, wherein th e con trol to cope wit h t he p ro bl em p erform ed b y th e fi rst r adio sta ti on in clu des at le ast one of : con trol to r ecov er t he ra di o lin k of th e ra di o termi nal in th e se cond cell ; con trol to r el eas e th e ra di o l i nk of th e radio t erm inal in th e sec ond cell ; or co nt rol t o est ablish a r adio li nk o f the r adi o t ermin al in a cel l d iff ere nt from th e secon d ce ll .

41. A com municati on c ontrol m ethod in a se cond ra dio s tati on t hat s erv es a second cell, th e m eth od com pri si ng: commu nic ati ng with a radio te rm in al in c arrier a ggregatio n o f a 25 fi rst cell s erved by a f irst radio st at io n an d th e se cond cell; and t ransmitt ing , to t he fi r st rad io s tat i on , in f or m atio n ab out a r a dio l i nk pro blem o ccurrin g in a radio l ink in th e seco nd c el l bet we en the s econ d r adi o station and th e r ad io t ermin al w hil e th e carrier aggre gat ion is bein g pe rfo rmed . 30

42. The communication control method according to Claim 41, wherein th e i nforma ti o n ab o ut the ra di o link problem incl ud es at l ea st one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id ent if ie r , a be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y 48 m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermi nal lo cat ion in fo r matio n.

43. The communication control method according to Claim 41 or 5 42, wher ein th e prob lem in clu des at le ast one of r adio lin k di s con ne cti o n, call disco nn ecti on, a lo ss of s yn ch r oniz atio n , receiv ed quali t y d egrad at ion , and th ro ugh pu t d egra datio n .

44. A com municati on c ontrol m ethod in a ra di o te rm inal , th e 10 method comprising: performi ng , w i t h a firs t radio st at ion , r adi o res ourc e co ntrol fo r a fi rst cell served b y th e firs t radio stati on a nd a s econ d cell ser ve d b y a seco nd rad io st atio n in o rder t o pe rfo rm ca rri er aggre ga ti on o f t he fi rst and s eco nd c ells; an d 15 t ransmitt ing , to t he fi r st rad io s tat i on , at l east on e o f : i nformat ion ab out a rad i o l ink p r oblem oc curring in a radio li nk in th e s econ d ce ll b etween the second r adio st atio n a nd the r adi o t ermin al while t he car ri er aggre ga tion is bein g pe r fo rm ed; and radi o link status i nformat ion ind icatin g t hat t he prob lem has b een det ected in th e radio 20 l i nk.

45. The communication control method according to Claim 44, wherein th e i nforma t io n abou t the ra di o link problem incl ud es at l ea st one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id ent if ie r , a 25 be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , an d t ermin al lo cati on in fo rm atio n.

46. The communication control method according to Claim 44 or 30 45, wher ein th e prob lem in clu des at le ast one of r adio lin k di s con ne cti o n, call disco nn ecti on, a lo ss of s yn ch r oniz atio n , receiv ed quali t y d egrad at ion , and th r ou ghput d egra datio n .

47. A non -tra nsit or y co m put er re adabl e me dium s tori ng a 49 program for causing a computer to perform a communication control m etho d in a first ra di o st ati on that s erv es a f irst cell , wherein the communication control method comprises: performi ng , w i t h a rad io t ermi nal , ra dio resou r ce co ntrol fo r th e 5 fi rst cell a nd a se con d cell se rv ed b y a s econd ra di o s ta tion t o pe r f orm ca rrier aggre gat ion o f t he first and secon d c el l s; and r ecei vin g, from at lea st on e o f th e secon d radio st atio n an d th e r adio t erminal , at least one o f: i nformati on a bout a r adio lin k prob l em oc cu rr ing i n a rad io link i n t he secon d cell b et we en t he se cond r adio 10 st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s b ein g pe rform ed; and r adio li nk st atu s in f or mat ion ind ic ating th at th e problem h as b ee n d ete cted i n th e radio l i nk.

48. A non -tra nsit or y co m put er re adabl e me dium s tori ng a program for causing a computer to perform a communication control m etho d in a s econ d r adio st atio n th at se rv es a se cond cell, wh erei n the communication control method comprises: commu nic ati ng with a radio st at i on i n ca r ri er aggre gat ion of a fi rst cell s erved by a f irst radio st at io n an d th e se cond cell; and t ransmitt ing , to t he fi r st rad io s tat i on , in f or m atio n ab out a radio l i nk pro blem o ccurrin g in a radio l ink in th e seco nd c el l bet we en the s econ d r adi o station and th e r ad io t ermin al w hil e th e carrier aggre gat ion is bein g pe rfo rmed . 25 49. A non -tra nsit or y co m put er re adabl e me dium s tori ng a program for causing a computer to perform a communication control m etho d in a rad io te r m i nal , w he rei n the communication control method comprises: performi ng , w i t h a firs t radio st at ion , r adi o res ourc e co ntrol fo r 30 a fi rst cell served b y th e firs t radio stati on a nd a s econ d cell ser ve d b y a s eco nd rad io st atio n in o rder t o pe rfo rm ca rri er aggre ga ti on o f t he fi rst and s eco nd c ells; an d t ransmitt ing , to t he fi r st rad io s tat i on , at l east on e o f : i nformat ion ab out a rad i o l ink p r oblem oc curring in a radio li nk in th e 50 second cell between the second radio station and the radio terminal while the carrier aggregation is being performed; and radio link status information indicating that the problem has been detected in the radio link.

The prese nt i nv ent ion rel ate s to a r adi o commu ni catio n s yst em
10 i n whi ch a rad io s tat i on commu nic ate s wit h a radio terminal b y usi ng a
pl urali t y of cells.
Background Art
[ 0002]
In o rd er to imp r ov e t he d egrad ati on of commu nic ati on qualit y
15 due to d r ast ic in cre ases i n mob il e tra f fi c i n re cen t yea rs a nd achie ve
f ast er co mm uni cat ion, t he st and a r diz at ion o f C arri er Aggre gat ion (C A) f uncti ons t hat ena ble a radio t erm in al (Us er Equi pm e nt (U E )) t o communicate with a radio base station (eNode B (eNB)) by using a pl urali t y of cells ha s been und ert ak en in th e 3 GPP Lon g Term
20 Ev ol uti on ( LTE ) . No te t hat th e cell s t hat a U E (U s er Equ ipm ent) can
us e i n C A are lim ite d t o a pl uralit y of ce ll s o f o ne eNB (i.e ., a pl urali t y of cells s erved b y on e eN B). [ 0003]
The cel ls t hat ar e used b y a UE in C A are cat ego riz ed into a
25 P r im ar y C ell (P C ell ) that h as al r eady be e n us ed as a s ervi ng cel l wh en
t he C A is start ed and a Se cond ar y C ell (s ) (SC ell (s ) ) tha t i s u s ed in addit ion t o th e PC ell or in d ep endence th ereon . E ach SC ell can b e us ed b y a UE as th e need ari s es , an d the use o f t hem can b e s to pped. Note t hat st arti ng t h e us e of an S Cel l i s call ed "ac ti vat ing" or
30 "a ctiv atio n". Simi larl y, s top pi ng th e use of an S C ell i s cal l ed
"d eactiv ating" or "d eact iva tion ". Non -A cc ess St r atum (N AS) mob ili t y
i nformat ion , s ecu rit y in fo rm ati on (secu rit y i nput ) and t he lik e are
t r ansmitt e d and r ecei ve d th r ough a P Ce l l d urin g radio conn ect ion ( re) -

3
es t abli s hme nt (RR C c onnectio n E stablishm ent/Re -est ablishm ent ) ( s ee
Non - patent Lite ratu r e 1). A do wnl i nk ( D L) C arri er an d a n up link (UL)
Carrier corresponding to a PCell are called "DL Primary Co mponent
Ca rri er (P CC)" an d "U L PCC ", res pectiv el y. Simil arl y, a D L Carrie r
5 and a UL Carrier corresponding to a SCell are called "DL Secondary
Component Carrier (SCC)" and "UL SCC", respectively. [ 0004]
A radio l ink recov er y p roced ure that is perform ed w h en ra dio l i nk disc onnecti on (R adio Lin k F ailu r e (R LF)) o cc urs in a r adio li nk i n
10 a PCell d uri ng down lin k data (DL d at a) tra nsmi s si on i n CA is
expl ain ed with refe r en ce to Fi g. 10 (No n -p ate nt Lit era tu re 2 ). H ere, i t i s assum ed that a U E us es a fi rst cell (C ell 1) s erv ed by an eNB as a P C ell and us es a s ec ond cell (C ell2 ) a s a n SCell. [ 0005]
15 In steps S1 and S2, the eNB transmit s DL data to the UE by
us in g th e P C el l ( C ell1) and th e SCell (C ell2 ). In a s tep S3, th e qu ali t y of th e ra di o link i n th e PCell deter i o r ate s an d the DL d ata t r ans miss ion f r om t he e NB to t he UE fai ls . In a ste p S4 , t he U E det ect s t he R LF in t he PC ell (C ell 1). In a ste p S 5, t he UE t ransmit s a req uest for the
20 r econ nectio n o f t he r ad io lin k i n the P C el l (Cell1 ) (RRC Co nne ction
Re est abl is hm ent Reque st ). In a st ep S6 , th e UE r ele as es the SC ell (C ell 2) ( S C el l (C ell2 ) rel ea s e). In a st ep S 7, t he eNB tr an smits a r esp onse t o th e re con nect ion r equest t hrou gh th e P Cell (C ell1) (R RC Co nn ection R eest abli s hm ent ) . In a s tep S 8, th e UE t ransmit s a re p or t
25 about t he compl eti on of the r eco nnectio n th ro ugh t he P Cell (Ce ll 1)
(RRC Connection Reestablishment Complete). As a result, the UE can r ecei ve DL d ata i n th e Cel l1 a gain. In a st ep S9 , the eN B transmi t s DL data t o the UE b y usin g th e PCel l ( C el l1). [ 0006]
30 In Fig. 10, an example in which the UE detects the RLF is shown.
However, when the eNB can detect the RLF before the UE does, the eN B m a y t r i gger th e re conn ec tio n. As de s cri bed a bov e, in ordi nar y CA , the UE or the eNB can detect an RLF occurring i n the PCell and r eestablish the r ad io l ink c onn ecti on . A cco r di ngl y, th e eNB an d t he

4
UE can re s um e data t r ans miss ion, thus ma ki ng it p oss i ble t o mi nimiz e
pa ck et lo s s es an d th e l ike ca us ed b y RLFs in th e P C ell. Not e t hat ,
when t he SC e ll (Cel l2) needs to be u s ed again a f te r the comp l etio n of
t he recon ne cti on, th e eNB tr an smit s c onfi gu ratio n i nform ati on fo r the
5 SCell to the UE (RRC Connection Reconfiguration including SCell
confi gurat ion) an d al so trans mi ts t o the UE a m essage indi ca ti ng s ta rt of us in g t he SC ell (cal led "Activ ation ").
Ci tation L ist
Non Patent Literature
10 [0007]
Non - patent Lite ratu r e 1: 3GPP TS 36 .30 0 V11 . 3.0, "E vol ved Un iv er s al T erres trial R adi o A cc ess (E -U TR A ) and Evol ved U niv ersal T erre stri al Radio Access Network (E -UTRAN); Overall descriptio n; Stage 2 (R el ease 11 ) ", S ec tion 7.5, Se pt emb er 201 2
15 Non-patent Literature 2: 3GPP TS 36.331 V11.2.0, "Evolved Universal
Terrestrial Radio Access (E -UTRA); Radio Resource Control (RRC); P r ot ocol s peci ficatio n (Rel ea s e 11)", S ectio n 5.3.7 and 5 . 3. 11, December 2012 Non-patent Literature 3: 3GPP RWS -120046, Samsung Electronics,
20 "Technologies for Rel -12 and Onwards", 3GPP TSG RAN Workshop on
Re l -12 an d On wa rds, Lj ubl jan a, Sl ov eni a, 11 - 12 J une 201 2 Non-patent Literature 4: 3GPP RWS -120010, NTT DOCOMO, "Requirements, Candidate Solutions & Technology Roadmap for LTE Rel-12 Onward", 3GPP TSG RAN Workshop on Rel -12 and Onwards,
25 Lj ub ljana , S lov eni a, 11 -1 2 J un e 20 12
Summary of Invention Technical Problem
[ 0008]
In carri er aggre gat ion (CA ) , p r ovidi ng a radio t erm i nal (UE)
30 wi th a fu nct io n of d et ectin g an R LF i n the p rim ar y cell (PCell) enab les
t he recon ne cti on o f t he radi o l i nk. No te th at th e C A d oes no t h ave a f uncti on o f det ectin g an R LF o ccurri ng in th e s ec ondary cel l (SCell). Th is is be ca use the SC ell i s a supp lem en tar y cell, and t hu s no se ri ous problem oc curs fo r t he com muni ca ti on as lon g as the radio li nk in th e

5 P C ell is normall y con nect ed . [ 0009]
M eanw hil e, int er-b as e st atio n ca r ri er aggre gati on (in te r -eN B
CA ) in w hic h cel ls o f di ff eren t radio b ase st ati ons (eN Bs) are
5 simul taneo us l y u s ed h as b een propo s ed (No n -pa te nt Li tera tures 3 a nd
4). For example, a cell of a macro base station (Macro eNB (MeNB)) and a cell of a low -power base station (Low Power Node (LPN)) are simul taneo us l y u s ed a s a PCel l and an S C el l, r e sp ec ti vel y. In int er -bas e s tat ion (or in ter -e NB ) carrie r aggre gat ion , beare r s are
10 i ndep en den tl y c on fi gure d i n t he PCe ll and th e S C ell and
communication is performed between an UE and the MeNB and between the UE and the LPN. [ 0010]
If t he ar chi te ct ure o f o r di nary CA is ap pli ed t o th e int er -eN B C A,
15 i t is conc eivabl e th at an MeN B co ntrol s c onfi gu rati on of r adi o
pa ram ete r s an d th e li ke fo r bo th th e PC ell a nd t he SCe ll i n th e int er -eNB CA. In this case, RLF detection in the PCell by the UE and the r econ necti on of th e radio l ink i n t he PCell c an b e p erfo rm ed in a m ann er si mi lar to that fo r th e ordin ar y C A. H ow eve r, RLF d et ect ion
20 and ac comp an yin g rad i o-li nk re conn ect ion i n t he SCel l are n ot
performed. Accordingly, the MeNB cannot recognize an RLF occurring i n the SCel l, t hus ca us i ng a po s si bil it y t hat a sta te w here
commu nic ati on (e.g., dat a tran smission ) i s not p r op erl y carri e d o ut in t he SC ell conti nue s. Th e co ntinu atio n of t he sta te wh ere
25 commu nic ati on i s not p rop erl y c arried out in th e S C ell cause s a
possi bilit y o f occurre nc es of p ack et losses. [ 0011]
One o f th e obj ect s o f th e pre s ent inv enti on is t o provi de a r adio commu nic ati on s yst em, a radi o s t ation , a radio t erm inal , a
30 communication control method, and a program which are contribute to
r eduction of p a c ket lo sse s ca used b y a n oc curren ce o f a radio l i nk problem (e.g., an R LF) i n a se cond ar y ce ll du ri ng c arrier aggr e gatio n of a plura l i t y of c el ls se rv ed b y d i ffere nt radio st ation s.
Solution to Problem

6 [ 0012]
In a fi r st asp ect , a radio comm unicat ion s yst e m in cl udes a fi rst
r adio sta ti on th at se rv es a fi rst cel l, a secon d r adio st ation t hat ser ve s
a seco nd c el l, and a radio t ermi nal cap able o f p erformi ng c arri er
5 aggre gat ion o f t he fi rst and s ec ond cells. T he firs t r adio st atio n is
confi gure d to p erfo rm , w i th the radi o t ermin al, rad io resou r ce co ntrol f or th e firs t and se cond cell s in o rd er t o pe rform t he c arri er aggre gat ion . At le ast o ne o f t he s ec ond r adio sta t i on and th e radi o t ermin al is con fi gu r ed t o tra ns mit , t o t he first radi o st ation ,
10 i nformat ion ab out a rad i o l ink p r oblem oc curring i n a radi o link in th e
s econ d ce ll b etween the second r adio st atio n and th e radi o te rm in al while t he car ri er aggre ga tion i s bei ng per fo r med . [ 0013]
In a se co nd aspect , a first rad io st ati on t hat se rv es a firs t cell
15 i nclu d es a comm unicati on c on trol u ni t . Th e comm uni cat ion co ntrol
unit s upp ort s carri er aggrega ti o n o f t he firs t ce ll and a s eco nd cell s erv ed b y a s ec on d radio st at ion . The co mmun ic at ion con trol unit pe rforms , wit h a ra di o te rm inal, r adi o reso urc e cont r ol for th e f irs t and s econ d ce ll s in ord er to perfo rm the carrie r aggregati on in th e rad io
20 t ermin al. Fu rt her , t he com mun icati on c ont rol u nit receiv es , fro m at
l east on e o f the se con d radio stat ion and th e rad io t erm inal , at le ast one o f: i nform atio n abou t a ra dio lin k prob lem oc cu r rin g i n a radi o l i nk i n th e se cond cell b etw een t he se cond r adio s tat ion a nd the r adio t ermin al while t he car ri er aggre gat i on is bei ng perfo rm ed; an d rad io
25 l i nk s tat us in format ion ind ic at ing t hat t he pro blem h as b een dete cte d in
t he radio lin k. [ 0014]
In a t hird asp ect , a s econd r adio stat ion that se r ves a se con d cell i nclu des a commu nic ati on con tr ol unit . Th e comm uni cati on co ntrol
30 unit s upp ort s carri er aggrega ti o n o f a fi r st cell s erve d b y a f irst radio
st at ion and th e s ec ond cell. Th e commu nic ation con trol uni t transmit s , t o t he fi rst radi o s tatio n , in fo rm atio n ab ou t a ra dio lin k prob l em oc cu rr ing i n a radi o l i nk i n t he secon d cell b et we en t he se cond r adio st at ion and a radio t erm ina l w hil e th e carri er a ggregat ion is b ein g

7 pe rform ed b y t he radio t erm ina l. [ 0015]
In a fo urth asp ect , a radio t erm inal in cl udes a com mu nicati on
cont ro l unit th at sup ports ca r rier ag gr ega t ion us ing a first cel l ser ved
5 b y a f irs t radio st ation as a fi rst cell and usin g a s eco nd cell s erve d b y
a seco nd rad io stat ion a s a secon d cell. T he co mmu nic at ion cont r ol unit per f orm s , wit h the first rad i o st atio n, ra dio resou r ce co ntrol f or t he first an d secon d cell s in o rder t o p erfo rm the carrier aggregati on. F urt her, th e comm uni catio n co ntrol un it transmi ts , to t he fi rst ra di o
10 st at ion , at leas t on e o f : info rmation about a rad io l ink problem
oc cu rr ing i n a radi o l i nk i n t he secon d cell b et we en t he se cond r adio st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s bei ng pe rform ed; and radio link st atu s info r mat ion ind ic ating th at th e problem h as b ee n d ete cted i n th e radio l i nk.
15 [0016]
In a fi f th as pect, a co mmun ic at ion cont r ol m eth od , i n a first r adio sta ti on th at se rv es a fi rst cel l, in cludes:
( a) p erfo rmin g , wi th a ra di o te rm inal , r adi o res ourc e co ntrol fo r t he fi rst cell a nd a se con d cell se rv ed b y a s econd ra di o s ta tion i n ord er to
20 pe rform carrier ag gregat ion o f the firs t an d secon d c el l s; and
( b) rece iving , from at le ast on e o f th e s ec ond radi o s tatio n an d t he r adio t erminal , at least one o f: i nformati on abo ut a r adio lin k prob l em oc cu rr ing i n a rad io link i n t he secon d cell b et we en t he se cond r adio st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s b ein g
25 pe rform ed; and r adio li nk st atu s in f orm atio n i ndi cat ing that the
problem h as b ee n d ete ct ed i n th e r ad i o l ink. [ 0017]
In a six th aspect, a co mmun ic at ion con trol met hod , in a se cond r adio sta ti on th at se rv es a se co nd c ell , inc ludes:
30 ( a) comm uni catin g wit h a radi o t erm in al i n ca rri er ag gr egatio n o f a
fi rst cell s erved by a f irst radio st at io n a nd th e se cond cell ; an d ( b) t ransmittin g , to the fi r st r ad io stat i on , in f orm ati on abo ut a radi o l i nk pro blem o ccurrin g i n a r ad io l ink in th e seco nd c el l bet we en the s econ d r adi o station and th e r ad io t ermin al w hil e th e carrier

8
aggre gat ion is bein g pe rfo rm e d .
[ 0018]
In a se ve nt h asp ec t, a commu ni catio n co nt rol met hod in a r adio
t ermin al in cl ud es :
5 ( a) p erfo rmin g , wi th a fi rs t r adi o st atio n, ra dio resou r ce co ntrol f or a
fi rst cell s erved by th e first radi o st at ion and a secon d c el l s erve d b y a
s econ d r adi o s t ati on i n order to pe rfo rm ca r ri er aggre gatio n o f th e first
and s econd cell s; and
( b) t ransmittin g , to the fi r st r ad io stat i on , a t le ast o ne o f : in fo r matio n
10 about a r ad io lin k probl em o cc urri ng in a radio li nk in the s econd cell
between the secon d r adio st ati on an d th e radio t erm inal whil e th e
ca rrier aggre gat ion is b ei ng p er f orm ed; and r ad io lin k st atu s
i nformat ion ind icatin g t hat t he prob lem has b een det ected in th e radio
link.
15 [0019]
In an ei ghth asp ec t, a p rogra m in clu des i ns truc tio ns for c ausi ng
a computer to perform a communication control method according to
t he ab ov e -d es crib ed fifth a sp ec t .
[ 0020]
20 In a nint h asp ect, a progra m in cl udes in stru ctio ns fo r causin g a
computer to perform a communication control method according to the
abov e - des crib ed si xt h a s pect .
[ 0021]
In a t ent h as pect, a pro gr am i nclud es inst ruct ions for ca us ing a
25 computer to perform a communication control method according to the
abov e - des crib ed sev enth aspect.
Advantageous Effects of Invention
[ 0022]
Accordin g t o the abo ve - desc rib e d asp ects, i t i s po ssib le to
30 provid e a r adio commu nicatio n s ys tem, a r adio st atio n, a ra di o termin al ,
a communication control method, and a program capable of
cont ri buti ng to red uctio n of pa cket l os s es ca us ed b y a n o ccu rrenc e o f a r adio li nk p robl em ( e. g., an R LF) in a se co ndar y ce ll d urin g car ri er aggre gat ion of a p luralit y of c el ls se r ved b y di fferent ra di o st ati ons .

9
Brief Description of Drawings
[ 0023]
F i g. 1 sh ows a co nfiguratio n ex am ple of a rad io co m m uni ca tion
s ys tem ac co rdi ng to a first em bodim ent ;
5 F i g. 2 sh ows a co nfiguratio n ex am ple of a firs t r adio st atio n
ac cordin g t o the fi rst em bodi men t ;
F i g. 3 sh ows a co nfiguratio n ex am ple of a s econd r adio stat ion ac cordin g t o the fi rst em bodi men t ;
F i g. 4 sh ows a co nfiguratio n ex am ple of a rad io te r mi nal
10 ac cordin g to the fi rst em bodi men t ;
Fig. 5 is a sequence diagram showing an example of a communication control method in a radio communication system ac cordin g t o the fi rst em bodi men t (P r oc edu re Ex ampl e 1) ;
Fig. 6 is a sequence diagram showing an example o f a
15 communication control method in a radio communication system
ac cordin g t o the fi rst em bodi men t (P r oc edu re Ex ampl e 2) ;
Fig. 7 is a sequence diagram showing an example of a
communication control method in a radio communication system
according to a second embodiment (Procedure Example 3) ;
20 Fig. 8 is a sequence diagram showing an example of a
communication control method in a radio communication system according to a second embodiment (Procedure Example 4) ;
Fig. 9 is a sequence diagram showing an example of a
communication control method in a radio communication system
25 according to the second embodiment (Procedure Example 5); and
F i g. 1 0 is a sequ en ce diagr am sho win g a procedu r e for r ecov erin g a radi o li nk in ca r ri er ag gr egat ion ac co rdin g to th e LT E ( r el a t ed - art).
Description of Embodiments
30 [0024]
S peci f ic e m bodi me nts are ex pl ai ned h ere inaft er in d et ail w ith r eferenc e t o t he d r awin gs . The sam e s ym bols ar e assi gn ed to th e s ame or corresp ondin g ele me nts th r ougho ut th e drawings, and d upli cated expl anatio ns a re o mitt ed as ne cessary.

10 [ 0025] First embodiment
F i g. 1 sh ows a co nfiguratio n ex am ple of a rad io co m m uni ca tion
system according to this embodiment. The radio communication
5 s ys tem ac co rdi ng to this em bod im ent i ncl udes a fi rst radi o st ation 1, a
s econ d r a di o st ati on 2, and a radio t erm inal 3. The r adi o station s 1 and 2 ar e con necte d to a co r e n et work 4 and s erv e f i rst and se cond cells 10 and 20 , re sp ecti vel y. Each o f the radi o statio ns 1 and 2 is, f or ex am ple, a radio b ase st ati on, a base st ati on cont r o l st at ion , o r a
10 simpl ifie d radio b ase st ati on h aving onl y s om e of t he fun cti ons
( pro tocol la yers ) of an ordi na r y rad io b ase st ati on. Th e rad i o t ermi nal 3 h as a fun ct ion o f , w hi le usi ng a cell o f on e r adi o b ase st ati on, usin g a cel l of anot her ra di o st ati o n . In ot he r w ord s, th e radio t erm in al 3 su pp orts a c arrie r a ggregatio n (or cell aggregat ion ) o f a p lurali t y of
15 cells se rv ed b y di f f erent r adio s tat ions. Note t hat th e di f f erent r adio
st at ion s m a y b e di f f erent b ase st ati ons ind epende nt of each ot her, or m a y be one radi o s tati on and ano th er rad io base st at ion d ep end ent on t he o n e r ad io s tat i on. Furth er, th e d i fferent r adio sta tions may b e r adio sta ti ons of different t yp es hav in g di fferen t f unct ion s.
20 [0026]
F or ex a mpl e, th e ra di o term ina l 3 can est abl is h a s eco nd radi o conn ect ion o n t he s eco nd cell 20 w hi le ma int ai nin g a fi rst ra dio conn ect ion o n t he fi r st cell 1 0. The ex pre ss ion "esta bl is hme nt of a r adio conn ecti on" co r respo nds t o , for ex ampl e, a s tate whe r e the radio
25 t ermin al 3 c an co mmun i cat e wit h a rad i o st ation ( e.g., t he ra di o s tati on
1 o r 2 ) , o r a sta te where th e radio te rm i nal 3 and a radio st at ion (e . g. , t he rad io st atio n 1 or 2 ) poss es s commo n in forma tion n ecess ar y fo r commu nic ati on t her eb et ween. In t his wa y, th e ra dio termina l 3 can simul taneo us l y use a pl ural it y of cells (e.g. , t he c ells 10 and 20 ) fo r
30 t r ansmitt ing or re cei vi ng sign al s (e.g ., us er da ta o r co ntrol
i nformat ion ) . Th e ex pres si on "s i m ultane ous u s e of a plu ralit y of cell s "
i s not l imit ed to a ctu al si mult aneo us re cepti on o r t ran s mis si on o f
si gn als in a pl ural it y o f ce lls. T hat is , it in cludes: a s tate whe r e t h e
r adio t erminal actu all y recei ves or tra ns m it s si gnal s in ei t her o ne o f

11
t he cells al tho ugh the rad io te r m i nal is able to r ec ei ve or tran sm it
si gn als i n both o f the cells; a s tat e where the r adio t ermin al rec ei ves
or t ransmit s si gna l s of di ffere nt t ypes in th e resp ectiv e cel ls; and a
st at e w he r e th e ra dio term ina l uses ea ch o f th e plu r al it y o f cells for
5 ei ther si gnal rece ptio n o r si gnal t r ansmi s si on.
[ 0027]
In vi ew o f th e carrie r aggre gat ion o f a p lura li t y of c ells ser ved b y d iffe r ent rad io st atio ns, t he fun ctio n of u si ng a plu r alit y o f cel ls s erv ed b y d i fferent radi o st ati ons can be called "inter - radi o st ation
10 ca rrier aggre gat ion ". Fu rt he r, in vi ew o f th e ab ove -d esc rib ed
simul tan eo us us e o f a pl ur alit y o f cel ls, th e f uncti on o f us ing a pl urali t y of cells s erved b y di f ferent ra di o st ati ons can also be call ed "D ual C onn ec ti on", "D ual Con ne ct i vit y", "Mult i Co nn ectio n", "Multi Co nn ectivi t y", o r t he lik e.
15 [0028]
The radi o t ermin al 3 m a y trans mit to th e r adi o st atio n 1 o r t he r adio sta ti on 2 a t erm inal c apa bi lit y r eport in dic at ing that t he rad io t ermin al 3 is cap a ble of p erf orm in g inte r - r adi o st atio n c arri er aggre gat ion (i.e., suppo rt s i nter -ra di o st ati on carri er a ggregatio n).
20 Al tern a t i vel y, t he radio t erm inal 3 ma y im pli cit l y in dic at e th at th e
r adio t erminal 3 s upp orts in te r - r adi o station carrie r aggre gat ion b y t he categor y o f th e ra dio term ina l 3 o r i ts d evice rel ea se n umb er. T he ca pabil it y of per f orming i nte r -ra di o st atio n carri er a ggre gatio n ca n al s o be call ed "dual - co nnection ca pabil it y" or "m ulti -conn ect i on
25 ca pabil it y" .
[ 0029]
Fig. 1 shows a Heterogeneous Network (HetNet) environment. S peci f ic all y, th e f ir st cell 1 0 sho wn in Fig. 1 h as cov era ge w id er th an t hat o f th e s eco nd c el l 2 0. Fu rt he r, Fig. 1 s hows a hi erarchic al cell
30 st ru ctu r e i n whi ch th e secon d cell 20 is di sp osed i nsi de t he firs t ce ll
10. N ote t hat th e c el l st r uc ture s ho wn in Fig. 1 i s mer el y a n ex ampl e. F or ex ampl e, th e first and se co nd cel ls 1 0 and 2 0 ma y h av e the s ame de gree of c overage . In oth er wo rds, th e radio comm unicatio n s ys tem according to this embodiment may be applied to a Homogeneous

12 Network environment. [ 0030]
Next , a n op eratio n of t he ra dio commu nic ation s yst em acco r din g
t o t his emb odim ent is expl ain e d i n a mo r e det ail ed ma nner. In a radi o
5 commu nic ati on s yst em a cco rd ing t o thi s em bodi ment, t he fi rst radi o
st at ion 1 has con trol and m an agem ent fun ction s ( e. g. , an RRC l ayer) f or th e firs t and se cond cell s 1 0 and 20 for p erformin g inte r -radi o st at ion ca r ri er aggre gatio n of t he fi r st and s ec ond cell s 10 and 20 . S peci f ic all y, th e f ir st radio st ati on 1 p erforms , wi t h th e radio t ermi nal
10 3, r adio re so urce con trol for th e cell s 10 and 20 i n order t o pe r form
ca rrier aggre gat ion o f th e ce lls 1 0 and 20. Th e fi rs t ra di o st ati on 1 m a y trans mi t a co nfiguration r el at ed to th e radi o r eso urce co nt rol to t he rad io t e rmi nal 3 i n t he fi r st cell 10 , or ma y t ransmi t t he confi gurat ion to th e radio t ermi nal 3 in t he s ec ond cell 20 t hrough the
15 s econ d r adi o station 2. In th e l att er case , al t hou gh th e fi rst ra dio
st at ion 1 t r ansmits t o the s eco nd radi o st ation 2 a m ess age co ntai ning t he co nfigu ratio n r el a t ed to t he rad io res ource c ont rol fo r th e seco nd cell 2 0, t he s econd r ad io s tat ion 2 do es not nece ssaril y hav e t o r eco gniz e th e co nte nt s o f t hat me ssa ge. A lte r nativ el y, t he s ec ond
20 r adio sta ti on 2 m ay r eco gn iz e t he cont ent s o f t he messa ge. When th e
s econ d r adi o station 2 t ransmit s the con f i gurat ion r el ate d to t he r adio r eso urce co nt rol in the s eco nd c ell 20, the secon d radi o st a ti on 2 m ay t r ansmit t he confi gura ti on in a mann er s imil ar to tha t fo r t r ansm itti ng ot her d ownl i nk data .
25 [0031]
At l east one of th e s eco nd rad i o st ati on 2 and the rad io te rm in al 3 t ransmit s , t o t he fi rst rad io s t atio n 1 , i nformati on a bout a radi o li nk probl em o ccu rri ng i n a radi o link b etw een th e s eco nd ra dio st ati on 2 and th e rad i o t erm inal 3 in the s econ d ce ll 2 0 (R adio li nk (R L) prob lem
30 r el at ed in f orm ati on ). In an ex ampl e, the r adi o li nk p r oblem i n th e
s econ d ce ll 20 trig gers th e fi rst ra di o s tati on 1 t o pe r fo rm cont ro l to cope with t hi s r ad io li nk probl em . T he co ntrol perf orme d b y t he fi rst r adio sta ti on 1 in clu des , fo r examp le, a t l east o ne of co ntrol t o r ec ov er t he rad io l ink o f t he radi o te rm in al 3 in t he se co nd cel l 20, cont r ol t o

13
r el eas e t he radi o l ink of th e r adio t ermin al 3 in t he s econd cell 20 , and
cont ro l to est abl is h a r adio li nk o f th e r adi o t ermin al 3 in a c el l
di fferent fro m the s econ d ce ll 20 (e.g., t he fi rst cell 10 o r a th ird c el l).
F or ex ampl e, b ased on th e i nform at ion abo ut t he r adio li nk p r oblem i n
5 t he s econd cell 2 0 , t he firs t r adi o st atio n 1 m a y t r ans mit , to eith er or
both o f t he s ec ond rad io s tat io n 2 an d the r adio t ermi nal 3 , an i nst ructi on for r ec ove rin g th e r adio l ink in th e s eco nd c ell 20, an i nst ructi on for est ablishi ng a rad io l ink in a differ ent c el l ( e.g., t he fi rst cell 1 0 o r a thi rd cell ) inst ead o f the second ce ll 20, an
10 i nst ructi on for r el ea sin g t he r adio li nk i n th e s ec on d cel l 20, or the
like. [ 0032]
The radi o link pro ble m in t he secon d cel l 20 in clud es , f or ex am ple, at least on e o f ra dio lin k di s connecti on or call di sco nn ecti on
15 ( both ar e c all ed "Radi o Lin k Fai lu re (R LF)") an d a lo ss of
s ynchro niz ation . The r adi o li nk p ro bl em in t he s econd cell 20 i s not
1 i m ited to s eriou s p robl ems i n whi ch t he radi o te rm i nal 3 cannot
pe rform commu nic ation i n t he secon d cell 2 0 . Th e ra dio lin k prob l em m a y be d egrad atio n o f re ce i ved q ua lit y or th ro ughp ut o f the r adi o li nk,
20 or m a y be an occu r r en ce of a th r esh old c r os sin g a le rt in dic ati ng t hat
t he r ecei ved quali ty of t he radi o l i nk i s l o we r th an a pre determ in ed quali t y or t he t hrou ghput is lo wer tha n a pred et ermi ned val ue . The r adio l i nk r ecei ve d qu ali t y ma y be , f or ex am ple , re cep tio n po we r o r a S i gnal t o Interfere nc e pl us Noi se Rat io (S INR ) .
25 [0033]
When t he se cond r adi o station 2 o r t he ra di o te rm inal 3 det ec ts a r adio li nk p robl em i n t he secon d cell 2 0, i t m a y tra nsm it th e i nformat ion ab out the r adio lin k pro blem (RL p ro blem r el at ed i nformat ion ) to th e fi rst ra dio s tat ion 1 . Furth er, wh en a p ro ble m such
30 as th e a bov e -d es crib ed radi o l in k probl em is l ikel y to occu r o r wh en a
problem ha d occurre d but has b ee n re cov ered , the second r adi o station
2 o r t he ra di o te rm inal 3 m a y t ran sm it in fo rm ati on abo ut th e rad io li nk
problem to th e first radi o st ation 1. In ot he r w ords , th e i nform atio n
a b o ut a r ad io lin k probl em in t he s ec ond cell 20 m a y in dic at e th at a

14
r adio li nk p robl em i s lik el y to occu r or tha t a ra dio lin k prob l em had
oc cu rr ed but has b ee n re co vered . W het her a ra dio link p r oblem i s
l i kel y t o o ccur or no t m a y be determin ed, for ex ampl e , b as ed on
whet her or n ot m ovin g sp ee d o f t he radi o t ermin al 3 o r a par am ete r
5 r el at ed to t he m ovin g sp eed i s e qu al to or ex ceeds a p r edet ermi ned
valu e ( e.g., b ased on whethe r or n ot th e radio t ermin al 3 is m ovi ng at hi gh spe ed ). [ 0034]
The radi o t ermin al 3 m a y vol unt ari l y tra ns m it info rm atio n ab out
10 a radio l ink p ro blem oc curring in the seco nd cel l 20, or m a y tra nsm it it
i n res pon s e to a re que st from t he fir s t r adio sta tion 1. Fo r ex amp le, upon d ete ctin g a ra di o link problem in th e secon d c ell 20 , th e r adi o t ermin al 3 m ay v ol unt aril y r ep ort t he i nformati on a bout t he radio li nk problem to th e first radi o st ation 1 th r ough the first c ell 10.
15 Al tern ati vel y, th e fi rst radi o station 1 m a y req ue st in fo rm ati on abo ut a
r adio li nk p robl em i n t he secon d cell 2 0 f r o m th e radio t erm inal 3 , an d t he rad io t e rmi nal 3 m a y tra nsm i t th e in fo rm atio n i n respo ns e to th e r equest . [ 0035]
20 S im ilarl y, th e s ec on d radio st at ion 2 ma y vo lunt aril y tra nsmi t
i nformat ion ab out a rad i o l ink p r oblem oc curring in th e seco nd c el l 20, or m a y t rans mit it in r es pon se to a re qu est from th e f ir s t radio sta ti on 1. In an exam ple, up on det ec tin g a r adi o li nk p ro bl em in a r adio li nk wi th t he rad io t ermin al 3 i n t he secon d cell 20 , th e s econ d rad i o
25 st at ion 2 m a y vol unt ari l y tra nsm it in f ormatio n ab out th e rad io link
problem to th e first radi o st ation 1. In anot he r ex ampl e, fi rstl y, t he r adio t erminal 3 ma y d etect a ra di o lin k probl em in th e seco nd c el l 20 . Next , t he radio t ermina l 3 m a y re po r t th e rad io l ink p r oblem , w hic h has oc curred in th e s ec ond c ell 20 , t o the first radi o st atio n 1 th r ough
30 t he first c ell 10 . Th en , th e fi rst r adio s tat ion 1 may re qu est t he se cond
r adio sta ti on 2 to t r ans mit in f orm ati on a bout th e r adi o l ink p r oblem . La stl y, t he seco nd radio st at ion 2 m ay t ran sm it to th e fir st r adi o st at ion 1 t he i nforma ti on a bou t th e r adi o li nk p ro bl em b etw ee n th e s econ d r adi o station 2 and th e radio t erm inal 3 in th e s eco nd cell 20 .

15
F urt her, in s ti ll anoth er ex am ple, fi r stl y, th e fi rst r adi o station 1 m a y
detect (o r s omehow re cogn iz e) a r ad i o l in k probl em b etw een t he ra di o
t ermin al 3 a nd the se cond r adio stat ion 2 in t he se cond cel l 20 . N ext ,
t he first radio st ation 1 m a y r equ est th e seco nd rad i o s tati on 2 to
5 t r ansmit i nfo rm ati on a bo ut th e r adio lin k probl em an d then the s econ d
r adio st atio n 2 ma y t r ansmi t th e i nfo rm ati on to t he first ra dio station 1. [ 0036]
The i nfo rm at ion abo ut a r adio lin k probl em (R L p rob lem r el at ed
i nformat ion ) may i n clude, fo r exam ple, a t l east o ne of th e bel o w -l is ted
10 i nformat ion el em ent s:
- Trigger in form atio n ;
- A t ermin al i dent ifie r ;
- A ce ll i den tifie r ;
- A be arer identi fi er;
15 - A data t ransmi ssio n/ recept ion st at us ;
- R adi o qu alit y measu r em en t info rmation ;
- Terminal moving speed information; and
- Termi nal l ocat ion in f orm ati on. [ 0037]
20 A m es s age t hat is tra nsmi tte d f rom th e r adio t erminal 3 to t he
fi rst rad io st ati on 1 th r ough th e first c ell 10 in o r der to re port a radio l i nk pro blem d et ected in the s eco nd cel l 20 in clud es th e
aforem enti on ed i nfo rm at ion abo ut t he r adio lin k pro bl em . Furth er, th is m es s age m a y in clu de a re qu est or p ropo s al fo r a release o f th e s ec ond
25 cell 2 0, or m ay i ncl ud e a r equest or p ropo s al f or est abl is hme nt o f a
r adio conn ecti on in a thi rd c el l diffe r ent from bo t h the fi rst an d s ec ond cells 10 and 20 . [ 0038]
As d es crib ed ab ove , in thi s embodi ment, t h e fi r st radio stati on 1
30 pe rforms , wit h the radio t ermin al 3 , ra dio link con t ro l f or the cells 10
and 20 i n ord er to perfo r m int er-r ad i o st ati on carri er a ggregatio n of t he cells 10 an d 20. Further, at least on e of the se con d r adi o st atio n 2 and th e rad i o t ermin al 3 t ran sm its , t o the first radi o st atio n 1 , i nformat ion ab out a rad i o l ink p r oblem oc curring i n a radi o link in t he

16
s econ d ce ll 20 bet ween th e seco nd ra di o st ati on 2 an d the rad io
t ermin al 3 (R L pro ble m relat ed info r mati on). A s a res ult, th e fi rst
r adio sta ti on 1 can r ecogn iz e t h e ra di o link problem oc cu r rin g in t he
s econ d ce ll 20. Accordin gl y, f or ex am pl e, th e f irs t radio sta ti on 1 c an
5 pe rform c ontrol t o cop e w ith th e ra di o link problem in th e secon d cell
20. T hu s , thi s embo di men t ca n redu ce p ack et lo ss es ca us ed b y an oc cu rr en ce of a radi o link pro ble m in th e s eco nd c ell 20 d ur in g t he ca rrier aggre gat ion o f th e ce lls 1 0 a nd 20 s erv ed b y t he di f f eren t radio st at ion s 1 and 2.
10 [0039]
Next , c onfi gu rati on ex ampl es of t he r adi o station s 1 and 2 and t he r adio te r mi nal 3 ac co rdi ng to t hi s embo di men t a r e ex pl ain ed. Fi g. 2 is a b loc k d iagr am sh owi ng a co nfigu r ati on ex ampl e of the fi rst rad io st at ion 1 . A rad io co mm uni cat ion un it 11 receiv es an u plin k sign al
15 t r ansmitt ed from t he radi o te rm in al 3 tho rou gh a n a nt enn a. A
r eceptio n data proc ess in g uni t 13 resto r es th e re cei ved up link sign al. Th e obt ain ed recepti on dat a is fo rwar ded to anot he r net wo r k node su ch as a dat a t ransfer dev i ce o r a mo bili t y man ageme nt devi ce i n t he core network 4, or t o ot he r radi o s ta ti ons th r ough a comm un icati on un it 14.
20 F or ex ampl e, up lin k us er dat a receiv ed from th e rad i o t ermin al 3 is
f orward ed to a d at a transfe r d evice i n a high er - la ye r n etw ork. Fu rthe r , non - acces s st r at um (N AS ) cont rol d at a amon g cont ro l dat a receiv ed f r om t h e radio t erminal 3 is fo rwa rd ed to a m obilit y m a na gemen t devi ce in a h igh er -la yer netwo r k. Fu rt he r, t he r ec eption dat a
25 processin g unit 1 3 re ceiv es , from a comm unicati on c on trol un it 1 5,
cont ro l dat a t o be tr ansmitt ed t o th e ra di o st ati on 2, an d transmit s this cont ro l dat a t o th e radio st atio n 2 t hrou gh the comm unicati on unit 14. [ 0040]
A t ransmissi on d ata p ro cessin g unit 12 ac qu ires use r dat a
30 des tin ed for the r adi o t ermin al 3 from th e comm uni cati on un it 1 4 an d
generat es a t ransp ort chann el b y per f ormi n g e rro r co rrect ion en co din g, r at e matc hi ng, int erl eavin g, and th e lik e. Fu r the r , th e tr an smission data p r oc essin g un it 12 gen era tes a tra ns mi ssio n s ym bol seq ue nce b y addin g co ntrol in f ormatio n to t he data sequ en ce o f th e tr an sp ort

17
ch an nel . The radio c om muni c ati on unit 11 gen era tes a do wnl ink si gna l
b y p erfo rm i ng car r ie r mo dul atio n b ased on the t r ansmission s ym bo l
s equence, f r eq uenc y c onv ersion , s ign al am pl ificati on, and th e li ke, a nd
t r ansmits the gen erat ed do wnli nk si gn al t o the r adi o t ermin al 3.
5 F urt her, t he tra ns mi ssio n dat a process ing uni t 12 recei ves c on trol d at a
t o b e tra nsm i tted to the r adi o t ermin al 3 from th e com muni ca t i on cont ro l unit 15 an d transmit s th is cont r ol d at a to the r adi o t ermin al 3 t hrough the rad io c om muni cation un it 11. [ 0041]
10 The com muni catio n cont r ol unit 1 5 con t ro ls i nte r -radi o s t atio n
ca rrier aggre gat ion o f t he first and secon d c el l s 1 0 an d 20. S peci f ic all y, th e commu nicati on con tr ol un it 1 5 pe r f orms , w ith the r adio t erminal 3 in t he firs t cell 1 0 , r adi o reso urc e cont r ol for t he c ells 10 and 2 0 i n ord er to perfo r m ca rri er a ggregatio n of t he cel ls 10 and
15 20. F urt her , th e comm uni cati on c ontrol un it 15 recei ve s , fro m at least
one o f th e seco nd ra di o st ati on 2 an d th e radio t erm inal 3 , in fo r matio n about a r ad io lin k probl em b etw een t h e s ec on d r adi o st atio n 2 and t he r adio t erminal 3 in t he s econd cell 20 . Based on t he r ec ei ved i nformat ion ab out the rad io lin k p rob lem , th e c ommu ni cat ion control
20 unit 15 m a y p erfo r m cont ro l to cope wi th t his prob l em suc h as cont r ol
t o reco ve r t he radio l ink of th e ra di o term ina l 3 i n th e secon d ce ll 2 0, cont ro l to rel ea s e the rad io lin k o f t he ra di o te rm inal 3 in th e seco nd cell 2 0, or cont r ol to e stablish a ra di o link of th e ra di o term ina l 3 i n a cell d iff erent fr om t he secon d cell 20.
25 [0042]
F i g. 3 i s a blo ck d iagram sh owi ng a c onfi gu ratio n example of th e s econ d r adi o station 2. T he fu nctio ns and th e op erati ons of a radi o commu nic ati on unit 2 1, a t r ansmi ss ion dat a p roc es si ng uni t 22, a r eceptio n data proc ess in g uni t 23, and a commu nic ation u nit 2 4 sho w n
30 i n Fi g. 3 a r e simil ar t o tho s e of th ei r correspo nding e lem ents sh own i n
F i g. 2 , i . e. , tho s e of th e ra di o com mun ic at ion u nit 11, th e transmi ssio n data p r oc essin g un it 12, t he r ecep tio n dat a proc ess in g un it 13 , an d the communication unit 14. [ 0043]

18 A comm uni cat ion c on trol u ni t 25 , i n th e r adio st ati on 2 , cont ro ls
i nt er - r adio st ati on car ri er aggre gat i on o f t he first and s econ d c ell s 1 0
and 20 . Fu rth er, th e commu nic atio n con trol unit 25 m ay tra nsm it , to
t he first radio st ation 1 , info rmation about a r adi o l in k probl em
5 between the secon d r adio st atio n 2 and t he rad io te r mi nal 3 i n t he
s econ d ce ll 20.
[ 0044]
F i g. 4 i s a bl ock dia gram sho wi ng a con f i gurat ion exampl e o f the
r adio t erminal 3. A r adio comm unicatio n unit 3 1 s uppo rt s c arrier
10 aggre gat ion of a p lura l it y of cells se r ved b y di fferent ra di o st ati ons ,
and is ab le to simult aneousl y u s e t he p lura li t y of c ells ( e. g. , th e ce lls
10 and 2 0) fo r t r ansmitti ng o r recei vin g sign als. Sp eci f ic al l y, th e
r adio commu ni cation unit 31 r ec ei ves a d ownli nk sign al from o ne o r
both o f th e radi o s tatio ns 1 and 2 th r ough an an ten na. A r ec epti on d ata
15 processin g unit 3 2 restores re cept ion d at a from t he recei ve d down link
si gn al a nd s end s t he resto r ed re cept ion data t o a d at a cont ro l u nit 33 .
Th e dat a co nt rol u nit 33 use s the re c epti on dat a a cco rd ing to its
purpose. Furth er, a t ransmi ssion d at a proces si ng u nit 34 a nd a rad io
commu nic ati on unit 3 1 gener at e an u plin k sign al b y usi ng tra ns mi ssio n
20 data su ppli ed from th e d ata con t ro l unit 33 and t r an smit th e gen erat ed
uplink si gnal t o o ne o r b ot h of th e radio sta t i ons 1 a nd 2.
[ 0045]
A comm uni catio n con trol unit 35 , i n th e r adio t erminal 3 ,
cont ro ls i nt er -radi o st ati on car ri er aggre ga tion o f t he first and second
25 cells 10 and 20 . Fu rt her, t he co mmu nic ati on con tr ol unit 35 m a y
t r ansmi t , t o t he fi r st rad io s t atio n 1 , info rmat ion abo ut a rad io link
problem b et ween t he s econd ra di o s tat ion 2 and th e radio t erm in al 3 i n
t he s econd cell 2 0.
[ 0046]
30 Next, Procedure Examples 1 and 2 of a communication control
method in a radio communication s ystem according to this embodiment
are ex pla ined h ere ina fter.
[ 0047]
(Procedure Example 1)

19
In Pro ce dure Exampl e 1, t he ra di o ter mina l 3 t r ansmits
i nformat ion ab out a rad i o l ink p r oblem oc curring in th e seco nd c el l 20
t o t he fi rst radi o s tatio n 1. Fig. 5 sh ows an ex am pl e of a se qu en ce
diagram showing a communication control method according to the
5 P r ocedure Exampl e 1. In ste ps S 101 an d S 102, th e radio t ermi nal 3
pe rforms c arri er a ggr e gatio n of t he first and se co nd cel ls 1 0 and 2 0. Th at is , i n th e ste ps S 101 an d S10 2, th e f irs t radio st ation 1 t r an smits and/o r receiv es da ta or co nt rol in fo r m atio n to a nd/o r f r om t he ra dio t ermin al 3 in th e firs t cel l 10 an d the se cond r adio stat ion 2 trans mits
10 and/o r receiv es da ta t o an d/ or f ro m t he ra dio term ina l 3 in th e seco nd
cell 2 0. [ 0048]
In a st ep S 103 , t he r ad io te r mi nal 3 det ects a rad io l ink p r oblem oc cu rr ing i n a radi o l i nk bet ween the se cond r adio stat ion 2 and th e
15 r adio t erminal 3 in t he s econd cell 20 . Not e th at as d esc ri bed
previo us l y, t he ra dio term ina l 3 m a y detect th at a prob lem is lik el y t o oc cu r i n th e radio link in th e s eco nd c ell 20, o r d et ect th at a radio li nk problem h ad occu r r ed but has b ee n re cov ered . In a st ep S1 04 , t he r adio t erminal 3 tra nsmit s , to t he fi r st r ad io s tat i on 1 t hrou gh th e f irs t
20 cell 1 0, i nfo rm ati on ab out th e ra di o lin k probl em in th e seco nd c el l 20.
[ 0049]
Accordin g t o the p r oc ed ure sho wn in Fig. 5, the fi r st radio st at ion 1 ca n reco gniz e the ra di o lin k probl em oc cu r rin g in t he second cell 2 0 an d can r edu ce (or p r event ) pa cke t lo sses and the l i ke b y
25 appro pr iat el y co pi ng with t he p rob lem. Thou gh it is not cle arl y s how n
i n Fi g. 5, fo r ex am ple , the fi r st radio st ati on 1 m ay t ran smi t , to ei the r or bo th o f t he second radio sta t i on 2 and t he r ad io te r minal 3 , an i nst ructi on for r ec ove r ing th e r adi o l ink in t he s econd cell 2 0, an i nst ructi on for est ablishi ng a rad io lin k in a di f f erent c ell (e.g., th e
30 fi rst cell 1 0 o r a thi rd cell ) inst ead o f the second ce ll 20, or an
i nst ructi on for r el ea sin g t he r adio li nk i n th e s ec on d cel l 20. [ 0050] (Modi f i catio n of P rocedu r e Ex ampl e 1 )
The procedure shown in Fig. 5 is merely an example of a case

20
where info rmation abo ut a ra di o lin k probl em in t he s econd cell 20 i s
t r ansmitt ed from t he radi o te rm in al 3 to t he fi r st rad io s tati on 1. Th e
Procedure Example 1 may be modified as follows.
[ 0051]
5 F i rstl y, t he firs t r adio sta tion 1 re qu est s th e rad i o term inal 3 to
r eport in f orm ati on ab out a r adi o li nk p r oblem oc curring in th e s eco nd cell 2 0. Th en, t he r ad io te r minal 3 tra nsmit s t he info r mati on abo ut the r adio li nk p robl em o cc urri ng in t he secon d cell 20 , in re spon s e to the r equest f ro m th e firs t radio st at ion 1 . Th e information about a rad io
10 l i nk pro blem is n ot lim i t ed t o informat ion about a problem in th e
s econ d ce ll 20, but m a y i ncl ud e in forma ti on about a r adi o li nk probl em i n t he fi rst cell 10 or ot her c ells us ed b y th e rad i o ter mina l 3 . W hen no radi o link pro blem oc cu rs in t he s eco nd cell 20 o r no pr obl em is detect ed, t h e radio t erm ina l 3 m a y t r ansmit in f orma ti on in dic atin g tha t
15 t here i s n o p ro ble m ( o r no probl em i s det ec ted ) , i n r es ponse to t he
r equest f ro m th e firs t radio st at ion 1 . [ 0052]
The fi r st r adio sta ti on 1 ma y t ransmi t t o th e radio t ermin al 3 a condi tion ( s ) for de termini ng w heth er or no t th ere i s a radio li nk
20 problem. Th e rad i o termi na l 3 ma y d eter min e whet he r or no t th ere is a
r adio li nk p robl em b ase d on t his con diti on(s ). [ 0053] (Procedure Example 2)
In Pro ce dure Exampl e 1, t he se cond ra dio st ati on 2 tran smi ts
25 i nformat ion ab out a rad i o l ink p r oblem oc curring in th e seco nd c el l 20
t o t he f i rst ra dio s tati on 1. Fi g. 6 sh ows an exam ple o f a seque nc e diagram showing a communication control method according to the P r ocedure Exampl e 2. Pro cesse s in ste ps S20 1 an d S 202 ar e si mi lar to t hos e in t he st eps S1 01 and S 102 in Fi g. 5 , w hic h are e xpl ai ned abo ve
30 i n t he P ro ce dure Ex am ple 1 . In a step S 203, th e s ec on d rad io st atio n 2
detects a r adio l ink prob lem o cc urri ng i n a radi o lin k in t he second cell 2 0 b etween t he s econd r adio stat ion 2 an d th e radio t ermi nal 3. Th e s eco nd radi o s tatio n 2 ma y d ete ct th at a pro bl em is lik el y to o cc ur i n t he ra di o lin k bet ween th e s econ d r adi o station 2 and t he radi o

21
t ermin al 3, o r det ect th at a rad i o link prob l em had occu rr ed but h as
be en recover ed . In a st ep S 204 , t he s eco nd radi o st ati on 2 tran smit s
i nformat ion ab out th e r adio lin k pro blem i n the s econd cell 2 0 to the
fi rst rad io st ati on 1.
5 [ 0054]
Accordin g t o the p r oc ed ure sho wn in Fig. 6, the fi r st radio st at ion 1 ca n reco gniz e the ra di o lin k probl em oc cu r rin g in t he second cell 2 0 an d can r edu ce (or p r event ) p a cke t lo s s es and th e lik e b y appro pr iat el y co pi ng with t he p rob lem. Thou gh it is not cle arl y s how n
10 i n Fi g. 6, fo r ex am ple , the fi r st radio st ati on 1 m ay t ran smi t , to ei the r
or bo th o f t he second radio sta t i on 2 and t he r ad io te r minal 3 , an i nst ructi on for r ecov erin g t he ra dio lin k in th e seco nd c el l 20, a n i nst ructi on for est ablishi ng a rad io lin k in a di f f erent c ell (e.g., th e fi rst cell 1 0 o r a thi rd cell ) as a sub sti tu te fo r t he s ec ond cell 20 , o r an
15 i nst ructi on for r el ea sin g t he r adio li nk i n th e s ec on d cel l 2 0.
[ 0055] (Modification 1 of Procedure Example 2)
The procedure shown in Fig. 6 is merely an example of a case where info rmation abo ut a ra di o lin k probl em in t he s econd cell 20 i s
20 t r ansmitt ed from t he second ra di o s tat ion 2 to t he firs t rad i o st a t ion 1 .
Th e P roc edu re Ex ampl e 2 may b e modi fi ed as foll ows. Fi rst l y, t he fi rst rad io st ati on 1 req uests t he secon d radio st at ion 2 to repo rt i nformat ion ab out a rad i o l ink p r oblem oc curring in th e seco nd c el l 20. Th en, the s econ d r adi o station 2 t ransmi ts th e i nform atio n abou t a
25 r adio li nk p robl em o cc urri ng in t he secon d cell 20 , in re spon s e to the
r equest f ro m th e firs t radio st at ion 1 . Th e information about a rad io l i nk pro blem is n ot lim i t ed t o informat ion about a problem in th e s econ d ce ll 20, but m a y i ncl ud e information about a probl em in anot he r cell t hat i s se rved b y t he s econd r adio sta tion 2 an d us ed b y th e rad i o
30 t ermin al 3. W hen no ra di o link problem oc cu rs in t he s eco nd c ell 20 o r
no probl em is d et ect ed, the s econ d r adi o station 2 m a y tra ns mi t i nformat ion ind icatin g t hat t he r e i s n o pro bl em (or n o prob lem is detect ed) , in resp onse to t he re qu est from th e f irs t radio sta ti on 1. [ 0056]

22
The fi r st r adio sta ti on 1 ma y t ransmi t t o th e secon d radio st ation
2 a con diti on(s ) fo r d etermi nin g whethe r o r n ot there is a radio li nk
problem. Th e s ec ond rad io s t atio n 2 m ay d et ermi ne wh eth er o r n ot
t here i s a radi o lin k pro bl em ba s ed on th is condi tion ( s).
5 [ 0057]
(Modification 2 of Procedure Example 2)
The P r oc edu re Ex ampl e 2 may b e modi fi ed as foll ows. Fi r s t l y, t he rad io t e rmi nal 3 detects a rad i o l ink p r oblem i n the s econd cell 2 0 and reports , to th e firs t radio st at ion 1 , r ad io l ink st at us info rm ation
10 i ndicati ng that th e ra di o te rm inal 3 has d et ected t he ra dio lin k pro bl em .
Next , th e fi rst r adio s tat ion 1 req uests t he second ra di o st ati on 2 to t r ansmit i nforma tion about t he r adio lin k probl em in th e seco nd c el l 20 r egard ing t he radio t ermi na l 3, f r om wh ich th e r ad io l ink st at us i nformat ion has been o rigi nat ed . Then, th e s eco nd rad i o st atio n 2
15 t r ansmits th e in fo r mati on abo ut the ra dio link problem to th e f i rst
r adio sta ti on 1 in r es ponse t o t he reque st from t he firs t r adio station 1. Th e radi o li nk stat us in fo r mat ion trans mitted fr om t h e radio t erm inal 3 t o t he fi rst radi o s tatio n 1 ma y in clu de, for ex ampl e , a cell i den t i fi er (C ell ID ) of th e c ell wh ere t he prob lem has b een det ected an d the t yp e
20 of th e pro bl em (i.e ., i nform ation i ndi cat i ng wh at kin d of probl em h as
oc cu rr ed ). [ 0058] Second embodiment
In th is emb od iment, an ex am ple wh ere t he ab ove -d es crib ed fi rst
25 embodiment is applied to a 3GPP LTE system is explained. A
confi gurat ion ex ampl e of a ra dio co mmun ic ati on s ys te m acco rd ing to t hi s embo diment ma y b e s imil ar to that sh own in Fi g. 1 . N ote th at th e r adio sta ti ons 1 a nd 2 co r r espo nd t o e NB s, t he r adio te rm i nal 3 corresponds to an UE, and the core network 4 corresponds to an EPC
30 ( Evol ved P a ck et Co r e). T r ansmi ss ion a nd recept ion of in fo r matio n
between r adio st atio ns (i.e ., be t ween e NBs ) m a y u s e an X2 i nte rface , which is a direct int erface, ma y use an S1 i nte r face t hrou gh the EPC , or m a y use a n ewl y-d efi ned i nte r f ace ( e. g. , an X3 in t erface ) . The f oll owi ng ex planat ion is giv en on th e assumpti on th at: th e r adio

23 st at ion s 1 and 2 a r e e NBs 1 an d 2; t he r adio ter min al 3 is an UE 3; an d the core network 4 is an EPC 4. [ 0059]
The radi o t ermin al (U E) 3 c an e stablish a s econd r adio
5 conn ect ion in th e se cond cell 2 0 (Cell 20 ) whi le m ai ntai nin g a fi rst
r adio conn ecti on in the fi r st cell 1 0 (Ce ll 1 0). Th e ex pres si on "e stablish ment o f a r adio conn ectio n" co r respo nds t o, f or ex am ple , a state where the UE 3 can communicate with an eNB (e.g., the eNB 1 or 2) (e. g. , a stat e w he r e RRC C onn ect ion S et up h as al read y be en
10 completed), or a state where the UE 3 and an eNB (e.g., the eNB 1 or
2) po s s es s c om mon in f orm ati on (e.g., U E con t ext ) n ec essary fo r commu nic ati on t her eb et ween. M ore sp ec ifi c al l y, t he U E 3 s upp orts ca rrier aggre gat ion o f a pl ural i t y o f c ells s erve d b y d iffe r ent rad io st at ion s (e NBs) (c all ed " Int er - eN B C A" or " Inter - Sit e CA"). N ot e th at
15 t he t erm " Int er - eNB CA " in t his s pe cificatio n is no t limit ed to a ctu al
simul taneo us receptio n o r t r ansmiss ion of sign als i n di ff eren t eNB cells. For exampl e t h e "In te r -e NB CA" in clu des : a stat e wher e th e r adio t erminal (UE) a ct ual l y r ec eiv es o r trans mits s i gnal s (e. g. , u ser data or con trol info rm atio n) i n eit her on e of t he eNB cells al tho ugh t he
20 UE 3 i s able t o recei ve o r transmit si gnal s i n both o f t he di fferen t eNB
cells; a st ate w he r e t he radio term in al re ceiv es or t ran smi ts sign al s of di fferent t ypes i n th e r es pect ive c ell s o f di f ferent eN Bs ; and a st at e where the r adio t erminal uses e ach o f t he c ell s of d iff e rent e NBs for ei ther si gnal rece ptio n o r si gnal t r ansmi s si on.
25 [0060]
As an ex ample to wh ic h th is emb od iment is appl ie d, it i s conceiv abl e that th e UE 3 p erfo rms inte r - r a di o base stat ion carrie r aggregation (Inter-eNB CA) in which the UE 3 uses the Cell 20 of the eN B 2 as a s eco nda r y cell (SCe ll ) whil e the UE 3 is al read y us i ng th e
30 Ce ll 1 0 of t he eN B 1 as a prim ary cel l (P C ell). T he prima r y cel l
(P Cell ) i s a cell t hat h as al r ead y b ee n us ed sin ce before t he C A is
st art ed . In con tra st to th is , th e s ec ond cell (SC el l ) is a cell th at is
us ed (ac tiv at ed ) i n addi tion to t he P Cell o r i n dep end en ce ther eo n on
t he preco nditio n th at t he U E 3 is al r ea d y con necte d t o the p r i m ar y ce ll .

24
Non - Access St r atum (N AS ) m obili t y info rm atio n, secu r it y i nfo rm ati on
( or securit y in put ) , a nd the l ike ar e tra nsmit ted and recei ve d th rou gh
t he PC ell when a r adi o conn ec ti on is est ablished (i .e. , at th e t ime o f
RR C C onn ect io n E st abli shm ent ) o r reesta blis h ed (i . e., at t he t ime o f
5 RRC Connection Re-establishment). A DL Component Carrier used for
the PCell is a DL PCC, and an UL Component Carrier used for the PCell is an UL PCC. Similarly, a DL Component Carrier used for the SCell is a DL SCC, and an UL Co mponent Carrier used for the SCell is an UL SCC.
10 [0061]
The radi o t ermin al (U E) 3 e st ablish es a radio con ne ction (RR C Co nn ection ) with th e fi rst ra di o bas e s tatio n ( eN B) 1 in th e fi rst c ell 10 (Cell 10 , e.g., P C ell ), and est abli sh es a radi o conn ect ion with t he s econ d r adi o b ase statio n (e NB ) 2 in th e seco nd c el l 20 (C ell 20 , e. g. ,
15 S C ell ) . Th e eNB 1 has con trol an d man agem ent fu nc ti on s (e.g., an
RR C layer) in th e Cell 10 and t he C ell 2 0. Sp eci fi call y, t he eNB 1 preforms , wit h the U E 3 , rad i o resou r ce co nt rol f or th e C el l 10 a nd the Ce ll 2 0 in ord er to perfo rm ca r rier aggre gat ion o f t he Cell 1 0 and t he Ce ll 2 0. The eNB 1 ma y transmit a confi guratio n rel at ed to t he rad io
20 r eso urce co nt rol (e . g., R adio R esou r ce C onfi gurat ion) to t he U E 3 in
t he C ell 1 0, o r m a y tra nsm it t he co nfigu r atio n to th e UE 3 th rou gh th e Ce ll 2 0 v i a t he eN B 2. In t he l at ter c ase, alth ou gh t he eNB 1 transmit s a m ess age i n cl udi ng t h e con fi gurati on , whi ch is re lat ed to th e radio r eso urce co nt rol fo r the Ce ll 20 , to t he eNB 2 th r ou gh an X2 in te r f ac e
25 or an S1 in t erface (o r a ne w interface), th e eNB 2 do es not neces s aril y
have t o re cognize the co nte nt s o f t hat me s s age. Alt ernativ el y, t he eN B 2 may recognize the content s of the message. When the eNB 2 t r ansmits the con fi gurati on rel ated to th e r adio res ourc e cont r ol i n th e Ce ll 2 0, the eNB 2 ma y transmit th e c onfi gu ratio n o n a D at a R adio
30 Be arer (DR B ) in a ma nner sim i l ar t o t hat fo r tra ns mi tti ng oth er data.
[ 0062]
At least one of the eNB 2 and the UE 3 transmits , to the eNB 1, i nformat ion ab ou t a rad i o l ink p r oblem oc curring in a radio li nk between the eNB 2 and the UE 3 in the Cell 20 (RL problem related

25
i nformat ion ) . In an ex ampl e, t h e ra dio lin k probl em in th e Cel l 20
t r i ggers t he eNB 1 to p erfo r m c ont ro l t o co pe wit h thi s radio l i nk
problem. Th e co ntrol p erformed b y th e eNB 1 in cl ud es, fo r ex am ple ,
at l eas t one o f con tr ol to r ecov er t he rad io lin k o f t he UE 3 i n the C ell
5 20 (Radio Li nk Recov er y), con trol to release the r adio lin k of t he UE 3
in the Cell 20 (Radio Link Release, RRC Connecti on Release), and cont ro l to est abl is h a r adio li nk o f th e UE 3 i n a c ell diffe r ent from t he Ce ll 2 0 (e.g., t he Ce ll 1 0 or a thi rd cel l ) (RRC C onnectio n S etu p). Fo r ex am ple, based on th e in f orma t i on about th e rad io l ink p r obl em i n th e
10 Ce ll 2 0 , the eN B 1 m a y t r ansmit , to ei the r o r b oth of th e eNB 2 and th e
UE 3 , an instru ct ion fo r r ecov erin g the radio l in k in t he C ell 20 , an i nst ructi on for est ablishi ng a rad io lin k in a di f f erent c ell (e.g., th e Ce ll 1 0 or a thi r d cell ) inst e a d o f t he C ell 2 0, an instru ct i o n f or r el easi ng the radi o l i nk in t he C ell 2 0, or th e lik e.
15 [0063]
The radi o link pro ble m in t he Cel l 20 includ es, for ex a mpl e, at l east on e o f radi o link disc onn ecti on or c al l disc onnectio n ( both ar e call ed "R adi o Lin k Fai lu re (R LF ) ") and a l os s of s yn ch ron iz ation. Th e r adio li nk p robl em i n t he C ell 20 i s no t li mited to seriou s p r oblem s in
20 which the UE 3 cannot perform communication in the Cell 20 . The
r adio li nk p robl em m a y be de gr adation of re ce i ved q ua lit y or t hrough put of th e ra di o link , o r may b e a n o cc urrenc e o f a th r eshold cros si ng al ert i ndi cati ng th at t he re ceiv ed q ual i t y o f the rad io link i s l ower t han a p redetermi ned qu ali t y o r th e throu ghpu t i s lo we r th an a
25 predetermi ne d v alu e. Th e radio l ink re cei ved qu ali t y ma y b e, fo r
example, Reference Signal Received Power (RSRP), Reference Signal Re ceiv ed Quali t y ( RS R Q), o r R ec ei ved Sign al Stre ngth Indi ca tor (R SS I) . [ 0064]
30 When the eNB 2 or the UE 3 detects a radio link problem in the
Ce ll 2 0, it m a y t r ansmit in f ormati on a bout th e r adio lin k prob l em (R L problem r el at ed i nfo rmat ion ) t o th e eNB 1 . Furth er, w hen a p robl em su ch as th e abov e -d es cribed r ad i o l ink p ro blem i s li kely to oc cu r o r when a r adi o l ink p ro bl em ha d occurre d b ut has been r ec overed , th e

26
eNB 2 or the UE 3 may transmit information about t he radio link
problem to th e e NB 1. In oth er words, t he in f orm ati on a bou t a radi o
l i nk pro blem in th e C ell 20 m a y in di cat e th at a ra dio link pr oblem is
l i kel y t o o ccur or th at a r adio li nk probl em ha d occurre d b ut ha s been
5 r ecov ere d . Wheth er a r adi o li nk problem is likel y to o ccu r o r n ot m a y
be determined, for example, based on whether or not moving speed of t he UE 3 or a p aramete r rerated to th e m ovin g s pe ed (e.g., Mob ilit y S t ate) i s equ al to or exceeds a p r ed etermi ne d valu e ( e.g., bas ed on whet her or n ot t he mob ile termin al is movin g a t hi gh sp eed ) .
10 [0065]
The UE 3 ma y vo lun ta ril y t r ansmit i nform ati on a bou t a radio l i nk pro blem o ccurrin g in t he C ell 2 0, or m a y t ransmi t it in resp ons e to a requ es t f r om the eN B 1 . Fo r ex am ple , u pon detectin g a radi o li nk problem in t he C e l l 20 , t he UE 3 ma y volu nta ri l y repo r t t he
15 i nformat ion ab out the r adio lin k pro blem t o the eNB 1 th ro ugh t he Cel l
10. Al te rn ativ el y, t he eN B 1 m ay requ est i nform ation abo ut a radio link problem in the Cell 20 from the UE 3 , and the UE 3 may transmit t he in fo r matio n in r es po nse to t he reque st. [ 0066]
20 S im ilarl y, th e eNB 2 may vol unt ari l y tra nsmit info rmatio n ab out
a radio l ink p ro blem oc curring in the Cel l 20, or ma y t rans mit it in r esp onse t o a requ est fro m the eNB 1. In an ex ampl e, up on d ete ctin g a r adio li nk p robl em i n a radi o link wi th th e U E 3 in th e Cell 2 0, the eN B 2 ma y v olunt aril y transmit i nfo rm ati on abo ut the radi o li nk
25 problem to the eNB 1. In another example, firstl y, the UE 3 may
detect a radio link prob lem i n t he Cell 20 . Nex t, t he U E 3 ma y re port t he r adio lin k prob lem , w hi ch h as o cc urred i n th e Cell 20 , t o the eNB 1 through the Cell 10. Then, the eNB 1 may request the eNB 2 to t r ansmit i nfo rm ati on a bo ut th e r adio lin k probl em . La stl y, th e e NB 2
30 m a y trans mi t , t o t he e NB 1, th e i nforma tion about the radi o li nk
problem in th e rad i o l ink w it h th e UE 3 in th e Cell 20 . Furth er, in still a no ther exa m ple, fi rstl y, th e e NB 1 m a y det ect ( or som eh ow r eco gniz e) a radio li nk prob lem i n a radi o link b etw een t he U E 3 an d the eNB 2 in the Cell 20. Next, the eNB 1 may request the eNB 2 to

27 t r ansmit i nfo rm ati on a bo ut th e r adio lin k probl em an d then the eN B 2 m a y trans mi t the i nformati on to th e eNB 1 . [ 0067]
The i nfo rm at ion abo ut a r adio lin k probl em (R L p rob lem r el at ed
5 i nformat ion ) may i n cl ude, fo r exam ple , a t l east o ne of th e bel o w -l is ted
i nformat ion el em ent s:
- Trigger in form atio n ( T rig ger in fo rmati on) ;
- A t ermin al i dent ifie r (UE id ent i t y) ;
- A ce ll i den tifie r (C ell i den ti t y) ;
10 - A be arer identi fi er (b ear er id en tit y) ;
- A data t ransmi s s ion/receptio n statu s (d at a s tat us ) ;
- R adi o qu alit y measu r em en t info rmation (m ea suremen t i nform atio n) ;
- Terminal moving speed information (UE speed information); and
- Termi nal l ocat ion in f orm ati on (UE lo cat ion info rm ati on ). 15 [0068]
The t r igge r i nform ati o n m a y be a c ause o f th e tran sm is s io n of i nformat ion ab out a rad i o l ink p r oblem , o r , fo r examp le, in f orm ati on i ndicati ng t hat an RL pro blem h as been d ete cted in th e SC ell (S C ell R L problem) or i ndi ca ting wh ich t yp e o f t he ab ove -d es cribed radio li nk
20 problems h as occu r r e d. A lt ern ativ ely, th e tri gger info rmation ma y be
i nformat ion ind icatin g pu r pos e (o r i nte nt ion ) of tran smi ttin g i nformat ion ab out a rad i o l ink p r oblem , o r , fo r examp le , in fo rm ati on i ndicati ng what is expect ed b y t ransmit ti n g th e in fo rm atio n. For ex am ple, t he trigg er i nform atio n m ay in dicate a r ec ov er y of the radi o
25 l i nk, a rel ease o f t he radi o li n k, est abli shm ent o f a n ew ra dio lin k, or
t he lik e. [ 0069]
The t ermi nal id ent if i er may b e a tempo r ar y t erm ina l id enti f ie r in t he cell to wh ich th e in f o rm ation ab out the r adi o li nk p ro bl em is
30 r el at ed, or a term in al u niq ue identi fi er. Th e te mp orar y te rmin al
i dent if ie r i s , for e xam pl e, a C ell R adi o Ne t work Tem po rary Ide nt i fi er (C-RNTI), a Temporary Mobile Subscriber Identity (TMSI), or a Short M essage Au t henti cat ion C ode Id en ti ty ( Sh ort MAC - I) . The t ermi nal uniqu e id entifi er is, for ex am pl e, an In te r natio nal Mobi le Su bs criber

28
Id entit y ( IM S I).
[ 0070]
The cel l id en tifie r i s, fo r ex am ple, a p h ysi cal c el l identi fi er
(P hysi ca l C el l Id e ntifier (PC I) ), a l ogi ca l ce l l i den tifi er (E -UTRA N
5 Ce ll Glob al Id en ti fi er (ECG I)), an enha nc ed cell id en tifi er ( Enh an ce d
Ce ll ID (E -C ID)), o r a vi rtu al c ell i dentifi er (Vi r tua l C ell ID (V -C ID)).
[ 0071]
The beare r identi fi er m a y be an id ent if ie r of a ra di o beare r in
t he cell to wh i ch t he in fo rm ati on ab out th e r adi o li nk p ro bl em is
10 r el at ed, or an id en tifi er of a n etwo r k be arer. Th e radi o be arer
i dent if ie r i s, f or ex am ple, a D at a R adi o Be arer Id ent i t y (DRB - Ident it y).
Th e net wo rk bearer i denti fi er is , fo r ex am pl e, a n ep s - Beare r Id en tit y o r
an EPS Radio Access Bearer Identity (E -RAB ID).
[ 0072]
15 The dat a transmi ssio n/ recept ion st at us ma y be a s tatus rel at ed to
data t r ansmiss ion or data r ec eptio n in th e cel l to w hi ch t he info rm ati on
about t he radio l ink prob lem i s rel ated ( e.g. , a S eq uen ce Nu mber (S N)
S t atus o r a R adio Li nk C ont r ol (R LC ) St atu s ), or ma y b e in fo r matio n
i ndicati ng whether o r no t the r e i s d at a of whi ch tra nsmi ssio n o r
20 r eceptio n has not ye t been comp l eted ( e.g., a dat a fl ag ) .
[ 0073]
The radio quality measurement informatio n may be terminal
m easu reme nt res ults of t he cell to whi ch the i nfo rm at ion abo ut t he
r adio li nk p robl em i s rel ated, or a cell(s ) adjace nt t hereto . T he radio
25 quali t y me asu rem ent i nfo rmat ion ma y be in fo r matio n ind ic at ing
whet her o r n ot a pre determ ine d radi o q ualit y i s s ati s fi ed.
[ 0074]
The terminal moving speed information may indicate the moving
sp eed o f t he radi o te r mi nal ( UE speed ). Alternat ive l y, t he t erm inal
30 m ovin g sp ee d i nforma ti on m a y be in format i on ind ic at in g a le vel of th e
m ovin g sp ee d o f t he ra d io t erm ina l ( e.g. , Hi gh s peed, Med iu m s pe ed,
Low speed, or Normal speed; or the Mobility State is High, Medium, or
Normal ) , o r may b e i nfo rmat ion ind icati ng whethe r or no t the m ovin g
sp eed o f t he radi o te r mi nal sa t i s fi es a pred eter min ed con diti on (e.g.,

29 i n fo rmat ion i nd icatin g whether or no t t he r ad io te r minal i s a hi gh -sp eed m obil e t ermin al ). [ 0075]
The t ermi nal lo cat ion info rm ati on may b e lo cat ion info rm atio n
5 of th e ra di o termi nal (e.g., Gl obal P os it i oni ng S ys t em (GPS ) l ocatio n
i nformat ion or po s itioni ng i nformat ion ) , or may b e in format ion i ndicati ng a rou gh lo catio n of t he ra dio t erm ina l ( e.g. , an R F fi ngerp r int whi ch is a com bin ation o f a r adi o q ual it y a nd a c ell ID). Al tern ati vel y, th e te rmi nal l oc at ion i nformati on m a y b e i nform ati on
10 i ndicati ng whether t he radi o te rm in al i s lo cat ed ou tdoo rs o r in doors.
[ 0076]
A message that is transmitted from the UE 3 to the eNB 1 t hrough the Cell 10 in o rd er t o rep ort a rad io l ink p r ob lem , whi ch had oc cu rr ed i n the Ce ll 2 0 , i nc l udes a f orementi one d i nforma tio n abou t t he
15 r adio li nk p robl em . Furth er, t hi s m ess age m a y in clu de a r equ est or
proposal for a rel ea se o f th e Cell 20 (S Cell r ele as e req uest, or S C ell ( r e)con fi gurat ion re quest - re le ase), or m a y i ncl ud e a r equest or proposal for esta blis hment of a rad io co nnectio n in a th ird c ell di fferent fro m bot h t he C ell 1 0 and t he C ell 20 (S C ell
20 ( r e)con fi gurat ion re quest - Cel l 3 add itio n).
[ 0077]
Next, Procedure Examples 3 to 6 of a communication control m etho d pe r f orm ed in a radio comm un icatio n s ys tem ac c ord ing t o th is em bod iment a r e expl ain ed h erein afte r . Not e that , it is assum ed t hat
25 t he UE 3 p erfo rms i nte r - r adi o b ase sta ti on c arri er aggr e gatio n ( In te r -
eNB CA) in which the UE 3 uses the Cell 20 of the eNB 2 as the SCell while t he UE 3 i s a lr ea dy u s in g th e C ell 1 0 o f t he e NB 1 as t he P C ell. The timer that the UE 3 uses to determine an occurrence of an RLF in t he C ell 2 0 (i.e. , t he SC ell ) m a y b e t he same t ime r as a ti me r T310
30 us ed for th e Cel l 10 (i. e., the PC ell ) , o r a d if f erent time r T3XY ( e.g.,
T312) may be defined. Furth er, the value of the timer T3XY may be t he s am e as o r d iffe r ent from that of th e t imer T3 10. Th e receiv ed quali t y t hres hol d(s) (Qi n an d Qout ) us ed for de te rmin in g an occurre nc e of an RLF may be the same as a threshold(s) for the PCell, or may be

30 di fferent from th e th resh old (s) for the PC ell ( e. g. , Qi n -SC ell a nd Qou t -S C ell ; o r Qi n2 and Qo ut 2). [ 0078]
(Procedure Example 3)
5 Procedure Example 3 corresponds to the Procedure Example 1
expl ain ed in th e f irs t embo dim ent. Th at is , t he U E 3 tra ns mit s i nformat ion ab out a rad i o l ink p r oblem oc curring in th e Cel l 20 (i. e., the SCell) to the eNB 1. Fig. 7 shows an example of a sequence di agram s howin g th e P ro cedure Ex ample 3. No te th at in Fig. 7 , the
10 Ce ll 1 0 (i.e., t he P Cell ) and t he C ell 20 (i.e., th e SCell) a r e ex p ressed
as "CELL1" and "CELL2", respectively. Further, one UE 3 is expressed as "UE 1". [ 0079]
In steps S 301 an d S2 02, th e U E 3 per f or ms carrie r aggregati on
15 of the CELL1 and the CELL2. Specifically, in the step S301, the eNB
1 t ransmit s downli nk c on trol si gnal s ( D L sign ali ng) or dow nlin k d at a (DL data), or both of them to the UE 1 in the CELL1. In the step S302, the eNB 2 transmits downlink data (DL data) to the UE 3 in the CELL2. [ 0080]
20 In steps S 303 an d S3 04, th e U E 3 dete cts a ra dio lin k prob l em in
the CELL2 (Radio link problem detection). In a step S305, the UE 3 t r ansmits info rm atio n abou t the ra di o link problem to th e eNB 1 t hrough the CE LL1 ( Rad io lin k p roble m r epo rt (i nclud ing Rad io l ink problem r el at ed i nfo rmat ion o f C ELL2)).
25 [0081]
In steps S306 to S309, the eNB 1 performs a process to cope wi th thi s p r ob lem upo n rece ivin g t he i nformati on a bout t he radio li nk problem occurring in the CELL2. That is, in a step S306, the eNB 1 i nst ruct s the eN B 2 to rel ea s e a beare r t hat h as been con fi gu red for th e
30 UE 3 (U E 1 i n Fi g. 7), which ha s det ect ed th e ra dio lin k prob l em in th e
CE LL2 (CELL2 recon f igu rat ion i ndicati on (i ncl udi ng requ est of UE1's be arer r el eas e)). In a st ep S 3 07 , t he e NB 2 rel ea s es th e be arer for th e UE 3 and re ports th e compl eti on of th e be are r rel ease t o the eN B 1 (C ELL2 re co nfi gu r atio n res pon s e (in clu din g compl eti on of UE1 's

31
be arer r el eas e)). In a st ep S 3 08 , t he e NB 1 in st r ucts the UE 3 to
r el eas e th e CE LL2 (i . e., th e be arer of th e CE LL2) a nd to reco nfigure
the radio resource configuration of the CELL1 (RRC Connection
Reconfiguration (including CELL2 release and CELL1
5 r econ f igu r at ion )).
[ 0082]
In th e ex am pl e s ho wn in Fig. 7 , the UE 3 cont inu es (i.e., ta kes over) the DL data reception performed in the CELL2 by performing it i n t he CE LL1 . In this case, t he instru ctio n to r econ figu r e th e ra di o
10 r eso urce c onfigu r ation o f t he C ELL1 i ncl ud es in fo r m atio n ne cess ar y to
i ndicat e, fo r ex ample, th at th e be are r co nfi gured i n the C E LL2 (i.e., used in the CELL2) should be reconfigured as a bearer in the CELL1, or that the data communication performed in the CELL2 (DL data r eceptio n i n Fig. 7) sho uld b e t ak en ov er b y per f orm ing it i n th e
15 CELL1. As a result, in a step S309, the eNB 1 transmit s to the UE 3
the DL signaling and the DL data in the CELL1. [ 0083]
According to the procedure shown in Fig. 7, the eNB 1 can r eco gniz e the r ad io li nk probl em o cc urri ng i n th e Cell 20 and ca n
20 r educe (or p rev ent ) p ack et lo sse s an d the lik e b y a pprop r iat el y co pin g
wi th th e pro bl em. [ 0084] (Modi f i catio n of P rocedu r e Ex am pl e 3 )
The procedure shown in Fig. 7 is merely an example of a case
25 where info rmation abo ut a ra di o lin k probl em in t he C ell 2 0 is
transmitted from the UE 3 to the eNB 1. The Procedure Example 3 may be modi f ied as fol lows. [ 0085]
When t he eN B 1 i nstru cts th e eNB 2 to rele as e t he b ea r er o f t he
30 UE 3, th e e NB 1 ma y req ues t the data comm un icatio n s tatus (e.g. , an
SN status) of the UE 3 in the Cell 20 from the eNB 2 and the eNB 2 m a y rep ort t he d at a co mm uni cat ion s tatu s to th e e NB 1. [ 0086]
Tho ugh it i s no t s hown in F ig. 7 , w he n th e eNB 1 t akes o ve r th e

32
be arer c onfigu r ati on of the C ell 2 0 con f i gured in t he eNB 2 and uses it
f or th e C ell 10 , it is al so ne ces s ar y to re co nfi gure th e core n etw ork
(EPC) 4. For example, the eNB 1 requests a Mobility Management
En ti t y ( M M E ) dispose d i n the EPC 4 to co nfi gure (o r re con fi gure ) th e
5 be arer f or t he U E 3, a nd t hen th e MME s en ds a be arer s etu p i ns truc tion
to the eNB 1. Further, the MME instructs an S-GW to change the User P l ane (Dat a) p ath (Pa th switch r eq uest) an d t he S-GW c hanges the path (P ath s wit ch). [ 0087]
10 Although Fig. 7 shows a case where a problem in downlink data
t r ansmission in t he C ell 2 0 is coped wi th, a prob lem in u plin k d at a ( U L data) t r ansmiss ion i n th e C ell 20 m ay be cop ed wi th in a simi l ar manner. [ 0088]
15 Fig. 7 shows an example where the eNB 1 controls establishment
of a radi o li nk for the UE 3 in t he Ce ll 10 in o rd er t o c ope wi th a rad io l i nk pro blem in th e C ell 20. Ho we ver, the eNB 1 m a y t ransmit , to th e UE 3 t hrou gh t he Cell 10 , an i nst ru ctio n fo r r ec overin g the radio li nk i n t he Cel l 2 0 or an instru ctio n fo r esta bli s hin g a radio li nk in a cel l
20 di fferent fro m bot h t he C ell 1 0 and t he C ell 20 ( e.g. , a t hird cell
(CELL3)). [ 0089]
The UE 3 ma y transmit t o t he eNB 1 a r equest to c onfigu r e (i.e . , addin g) a cell , i ns tead of t he C ell 2 0, a s a secon da r y c ell (SCel l ) , or a
25 r equest t o rem ove th e Cel l 20 from th e S C el l (s).
[ 0090] (Procedure Example 4)
Procedure Example 4 corresponds to the Procedure Example 2 expl ain ed in th e f irs t embo dim ent. Th at is , eN B 2 t r ansmits
30 i nformat ion ab out a rad i o l ink p r oblem oc curring in th e Cel l 20 to th e
eNB 1. Fig. 8 shows an example of a sequence diagram showing a communication control method according to the Procedure Example 4. Note t hat i n Fi g. 8, th e C ell 1 0 (i . e. , t h e PC ell ) and th e Cel l 20 (i. e., t he SC ell ) are ex pre ssed as "C E LL1 " an d "C ELL2 ", respectiv el y.

33
F urt her, on e UE 3 is exp res s ed a s "U E 1".
[ 0091]
P ro cesse s in s teps S 401 an d S 40 2 are simi l ar to th ose i n the
st eps S 301 and S302 i n Fi g. 7 , w hic h are ex pl ai ned ab ove in t he
5 Procedure Example 3. In steps S403 and S404, the eNB 2 detects that
there is a radio link problem between the eNB 2 and the UE 3 (UE 1 in
F i g. 8 ) i n t he CE LL2 (R adi o lin k p robl em d et ection f or U E 1). In a
st ep S405 , th e eN B 2 t ran sm its in fo rma ti on about t he radio li nk
problem to th e e NB 1 (Rad io l ink p r obl em repo rt (in clud ing R adi o link
10 problem related information of UE1 at CELL2)).
[ 0092]
In steps S406 to S409, the eNB 1 performs a process to cope
wi th th e pro bl em u pon recei vin g th e in f orm at ion ab out the rad io link
problem o ccu rri ng i n t he C E LL2. P roces s es in st eps S 406 t o S 409 ar e
15 simil ar to t ho s e in th e steps S 306 to S 309 in Fi g. 7.
[ 0093]
According to the procedure shown in Fig. 8, the eNB 1 can
r eco gniz e the r ad io li nk probl em o cc urri n g i n th e Cell 20 and ca n
r educe (or p rev ent ) p ack et lo sse s an d the lik e b y a pprop r iat el y co pin g
20 wi th th e pro bl em.
[ 0094]
(Modi f ic ati o n o f P r oc edure Ex am ple 4)
The procedure shown in Fig. 8 is merely an example of a case
where info rmation abo ut a ra di o li nk p rob lem in t he C ell 2 0 is
25 transmitted from the eNB 2 to the eNB 1. The Procedure Example 4
may be modified as follows.
[ 0095]
When t he eN B 2 d ete cts that the re i s a r adi o li nk p r oblem i n th e
radio link between the eNB 2 and the UE 3 in the Cell 20, th e eNB 2
30 m a y firstl y t ransm it a message fo r repo r tin g th e de te ct ion and th en
t r ansmit f ol low -u p m ess age c ont aini ng det ai led info rm at ion abo ut t he
r adio li nk p robl em . The fo ll ow-u p m ess age m a y be t ransmitt ed b y th e
eNB 2, for example, as a response message to a request from the eNB 1.
[ 0096]

34
Though it is not shown in Fig. 8, when the eNB 1 takes over the
be arer c onfigu r ati on of the C ell 2 0 con f i gured in t he eNB 2 and uses it
f or th e C ell 10 , it is al so ne ces s ar y to re co nfi gure th e core n etw ork
( EPC ) 4 . Th e recon fi gura ti on i n t he co re net wo rk may b e perform ed in
5 accordance with the procedure shown in the Procedure Example 3.
[ 0097]
Although Fig. 8 shows a case where a problem in downlink data t r ansmission in t he C ell 2 0 is coped wi th, a prob lem in u plin k d a ta (U L data) t r ansmiss ion i n th e C ell 20 m ay be cop ed wi th in a simi l ar
10 manner.
[ 0098]
Fig. 8 shows an example where the eNB 1 controls establishment of a radi o li nk for the UE 3 in t he Ce ll 10 in o rd er t o c ope wi th a rad io l i nk pro blem in th e C ell 20. H o we ver, the eN B 1 m a y tr ansmit , to th e
15 UE 3 t hrou gh t he Cell 10 , an i nst ru ctio n fo r r ec overin g the radio li nk
i n t he Cel l 2 0 or an instru ctio n fo r esta bli s hin g a radio li nk in a cel l di fferent fro m bot h t he C ell 1 0 and t he C ell 20 ( e.g. , a t hird cell (CELL3)). [ 0099]
20 (Procedure Example 5)
P ro cedure Exampl e 5 c orres pon ds to a modi f i cat ion of Pro ce du re Ex ampl e 2 ex plai ne d i n t he fi r st em bod ime nt . In th e P rocedu r e Ex ampl e 5, th e U E 3 r eports th e d etectio n of a r adio li nk pro bl em oc cu rr ing i n the Cel l 2 0 to t h e e NB 1 a s ra di o lin k statu s in f orm ati on,
25 t he eNB 1 r eq uest s i nformati on a bout t he ra dio lin k pro bl em from t he
eN B 2 , and t hen t he eN B 2 t ransmi ts t he in fo r matio n ab out the radio l i nk pro blem in resp onse to th e re qu est. [ 0100]
Th e radi o li nk stat us in fo r m ation m ay in clud e , f or ex ample , a
30 Ra di o Li nk F ai lure (R LF) re po rt . Not e th at al tho ugh t he R LF report in
t he LTE is info rm atio n abo ut an R LF i n th e PCel l, i t i s a ssum ed h ere t hat th e R LF rep ort is ext end ed to in f orm atio n ab out an R LF in th e S C ell . Th at i s, t he R LF repo rt m a y in clu de an y o f t he b elo w -li st ed i t ems:

35
- A n i den tifi er o f a n S C el l wh ere an R LF ha s b een de te ct ed ( f ai led SC el l Id) ;
- A terminal measurement result of an SCell where an RLF has been detect ed (measu reme ntR es ult La s t S ervSCe ll) ;
5 - A termin al measu r em ent r es ult at th e t i me of detecti on of an RLF i n
an SC ell (m eas R es ultN eighCe lls) ;
- Locatio n in form atio n of a rad io t ermin al at th e t i me of det ec ti on o f
an R LF in an S C ell (l ocati on Info ) ;
- A cause of detectio n of an RLF in an SC ell (rl f -C ause -S C ell); a nd
10 - A n elaps ed tim e a ft er a n R LF is d ete cted in a n S C ell
(t im eSi nc eFailu re -SCell).
Note t hat , in o rder t o indicat e a c ause of d ete ct ion o f an R LF in an SC ell , t 3XY-Ex pir y ( e.g., t31 2 -Ex pi r y) ma y b e n ewl y ad d e d t o th e ca uses of d et ect ion of an R LF in a PCell (i . e., th e s pecific atio n o f t he
15 current LTE).
[ 0101]
Fig. 9 shows an example of a sequence diagram showing a communication control method according to the Procedure Example 5. Note t hat i n Fi g. 9, th e C ell 1 0 (i . e. , t he PC ell ) an d the Cel l 2 0 (i.e . ,
20 the SCell) are expressed as "CELL1" and "CELL2", respectively.
F urt her, on e UE 3 is exp res s ed a s "U E 1". [ 0102]
P ro cesse s in s teps S 901 to S4 04 in Fi g. 9 are s imil ar t o those in t he s tep s S3 01 to S3 04 i n Fig. 7 , whic h are ex pl ai ned abo ve in th e
25 P r ocedure Ex ampl e 3. In a st ep S50 5, t he UE 3 re port s the det ectio n
of the r adio li nk prob lem t o t he eNB 1 as th e rad io lin k st atus i nformat ion (R adi o link p ro ble m repo rt (i nclud ing R ad io lin k st atus i nformat ion , e.g. , RLF in CELL2 ) ) . In a st ep S 506 , t he eNB 1 i nst ru cts t he eNB 2 t o t ransmit in for mat i on ab out th e ra dio link problem
30 r egard ing t he radio link with t he UE 3 (UE 1 in Fi g. 9 ), whi ch h as
detect ed th e rad io lin k probl em , an d to rel ea se th e b ea rer co nfigu r ed f or th at U E 3 (UE 1 in Fi g. 9 ) (C ELL2 re co nf i guration i nd icatio n (i nclu din g request o f R adi o lin k p ro ble m relat ed in f ormati on and UE1's be arer r el eas e)). In a st ep S 5 07 , t he e NB 2 rel ea s es th e be arer for th e

36
UE 3 and re ports th e in forma tion abou t the r adi o li nk p ro bl em and th e
compl eti on of the be arer rel ease to t he e NB 1 (CE LL2 recon f igu rat ion
r esp onse (i nclud ing R adio l ink p ro blem r el at ed in f orm atio n an d
compl eti on of UE1's be arer rel ease)). Pro cess es in the su bs eq uent
5 st eps S 508 and S509 are si mil ar to t hose in th e s te ps S30 8 an d S3 09 in
Fig. 7. [ 0103]
According to the procedure shown in Fig. 9, the eNB 1 can r eco gniz e the r ad io li nk probl em o cc urri ng i n th e Cell 20 and ca n
10 r educe (or p rev ent ) p ack et lo sse s an d the lik e b y a pprop r iat el y co pin g
wi th th e pro bl em. [ 0104] (Modi f i catio n of P roced u r e Ex ampl e 5 )
The procedure shown in Fig. 9 is merely an example of a case
15 where info rmation abo ut a ra di o lin k probl em in t he C ell 2 0 is
transmitted from the eNB 2 to the eNB 1. The Procedure Example 5 may be modified as follows. [ 0105]
Tho ugh it i s n ot s ho wn in F i g. 9 , w he n th e e NB 1 t akes o ve r th e
20 be arer c onfigu r ati on of the C ell 2 0 con f i gured in t he eNB 2 and uses it
f or th e C ell 10 , it is al so ne ces s ar y to re co nfi gure th e core n etw ork ( EPC ) 4 . Th e recon fi gura ti on i n t he co re net wo rk may b e perform ed in accordance with the procedure shown in the Procedure Example 3. [ 0106]
25 Although Fig. 9 shows a case where a problem in downlink data
t r ansmission in t he C ell 2 0 is coped wi th, a prob lem in t he u pli nk d ata ( U L d ata ) t r ans mission in t he C ell 20 m a y be co pe d with in a simi la r manner. [ 0107]
30 Fig. 9 shows an example where the eNB 1 controls establishment
of a radi o li nk for the UE 3 in t he Ce ll 10 in o rd er t o c ope wi th a rad io l i nk pro blem in th e C ell 20. Ho we ver, the eNB 1 m a y t ransmit , to th e UE 3 t hro ugh t he Cell 10 , an i nst ru ctio n fo r r ec overin g the radio li nk i n t he Cel l 2 0 or an instru ctio n fo r esta bli s hin g a radio li nk in a cel l

37 di fferent fro m bot h t he C ell 1 0 and t he C ell 20 ( e.g. , a t hird cell (CELL3)). [ 0108]
The UE 3 may transmit to the eNB 1 a request for configuration
5 a cel l, i ns tead o f th e Cell 20, as a s ec ond ary cel l (SCell) , or a re quest
t o remov e t he C ell 2 0 from the SC ell (s ) . [ 0109] Other embodiments
In th e first and se cond embo dim en ts , th e t ran smi ssi on and
10 r eceptio n of i nforma ti on (al so c alled "m essages") be t ween th e fi rst and
s econ d r adi o station s 1 an d 2 ma y b e pe r f orm ed b y u si ng, f or exampl e, a d irect int erface such as an LT E X2 i nte rface, o r m ay be p erformed t hrough an i nt erfa ce wit h a c ore netwo r k (e. g. , EPC ) 4 su ch a s an LT E S 1 i nt erface.
15 [0110]
The first and second embodiments can be applied to a case where t he first radio st ation 1 ( eNB 1) i s a mac ro radio bas e s tati on (M ac ro eN B (M eNB)) t hat s erv es (ma na ges ) a ma cro cell ha ving a r ela t i vel y l arge c ov erage an d th e secon d r adio sta ti on 2 (e NB 2) is a lo w -po we r
20 radio base station (Low Power Node (LPN)) that serves (manages) a
cell h avi ng a s mal l coverage . Exampl es of a LPN i nclud e a p i co -radio bas e s tat ion (Pic o e NB (P eN B)) ha vi ng fun ction s simi l ar to th ose of the MeNB and a new type of network node (New Node) having fewer f uncti ons t han t ho s e of th e Me NB . Alt ernati vel y, i t i s con cei vabl e to
25 employ a configuration in which a MeNB manages a LPN and control
f uncti ons ( e.g. , an RR C l a yer) i n an LP N c ell. F urt her, th e s eco nd c ell 20 may be a new type of cell (New Cell Type) which is different from conv enti on al cel l s and u s es a n ew t yp e o f carri er (N ew C a rrier T yp e) di fferent fro m con ven t i onal ca r ri er s .
30 [0111]
Each of the communication control methods performed by the r adio sta ti on 1 (co mmun ic at i on cont r ol u nit 1 5), th e ra di o st ati on 2 ( commu nic ati on con trol unit 25), and th e radi o te rmin al 3 ( commu nic ati on con trol unit 35) descri be d in t he fi r st and s ec ond

38
embodiments may be implemented by using a semiconductor processing
devi ce su ch as an App li cat ion S pe ci fic Int egrat ed Circuit ( AS IC ).
Al tern ati vel y, th ese m eth od s ma y be imp lem ented b y c a usin g a
compu ter s ystem in cludin g at le ast o ne proces s or ( e. g., Mi crop ro cessor,
5 Mi cro P r oc essin g Un it (MP U), o r Di gita l S i gnal Proc esso r (DS P )) to
ex ecut e a p rogram. S peci fic all y, on e or mo r e pro gr ams inc ludin g i nst ructi ons fo r ca us i ng a c omp ut er s yst em to pe r f orm algo rit hms sh own in t he f lo wcha rt s an d the se qu en ce dia gr am s ma y b e creat ed, and these programs may be supplied to a computer.
10 [0112]
Th es e p ro gram s ca n be s tore d in vari ous t yp es o f non -trans ito r y computer readable media and thereby supplied to computers. The non -t r ansito r y co mp ute r r eadable m edia i ncl udes var ious t yp es o f tangi ble st orage m edia. Ex amp l es o f t he no n - tr an sito ry c om puter read abl e
15 m edi a inc lude a ma gne ti c re cordin g med ium (su ch as a fl exi ble disk , a
m agneti c tape, and a hard di sk dri ve) , a magneto -opt ic recordin g medium (such as a magneto -optic disk), a CD-ROM (Read Only Memory), a CD-R, and a CD-R/W, and a semiconductor me mory (such as a mask ROM, a PROM (Programmable ROM), an EPROM (Erasable
20 PROM), a flash ROM, and a RAM (Random Access Memory)). Further,
t hese pro gram s c an be sup pl ied to c om put ers b y u si ng v arious t yp es of t r ansito r y co mp ute r r eadable m edia. Exa mples o f the t rans ito r y compu ter re adable m edi a i ncl ud e an el ec tri cal si gna l , an opti cal sign al , and an el ect rom ag neti c wave. T he trans it o r y co mpu t er reada ble media
25 can be used to supply programs to computer through a wire
commu nic ati on pat h su ch as a n el ectric al w ire an d an o pt i cal fib er, or wi rel es s c om mun icati on p at h. [ 0113]
In the first and second embodiments, an LTE system has been
30 mainly explained. However, these embodiments may be applied to
radio communication systems other than the LTE system, such as a 3GPP Universal Mobile Telecommunications System (UMTS), a 3GPP2 CDMA2000 system (1xRTT, High Rate Packet Data (HRPD)), a Global S ystem for Mobile Communications (GSM) system, and a WiMAX

39 s ys tem. [ 0114]
F urt her, th e abo ve - desc rib ed e mbo di men ts are mer el y e x ampl es
f or th e a pplicati on of t he t ec hnical id ea s ob tai ned b y t he prese nt
5 i nven tors. N eedl ess t o say, t h e s e te chni cal i de as a r e not l imi ted to t he
above-described embodiments and various modifications can be made t heret o. [ 0115]
This appli cati on is base d up on an d cl ai ms t he b enefi t of priorit y
10 f r om Japan ese pate nt appl icatio ns N o. 2013 - 038 971, file d on Febr ua r y
28, 2 013 , th e discl os ure of wh i ch is in corporate d herei n in it s ent iret y b y refere nc e.
Reference Signs List
[ 0116]
15 1 FIRST RADIO STATION
2 SECOND RADIO STATION
3 RADIO TERMINAL 10 FIRST CELL
20 SECOND CELL
20 15 COMMUNICATION CONTROL UNIT
25 COMMUNICATION CONTROL UNIT
35 COMMUNICATION CONTROL UNIT

40 WE CLAIM:
1. A radio communication system comprising:
a fi rst ra dio s tat ion that se r ves a fi rs t cell;
5 a seco nd radio st atio n th at s erv es a s ec on d cell; an d
a radio t ermin al c ap able o f p erformi ng c arri er a ggr egatio n o f th e fi rst and s eco nd c ells, wher ein
t he first radio st ation is c onfigu red t o perform , with th e rad i o
t ermin al, r ad io resou rce cont ro l fo r th e fi rst a nd s eco nd c ells in orde r
10 t o p erfo rm t he car ri er aggre ga tion , and
at l eas t one o f th e seco nd ra di o st ati on and t he ra dio te rm inal is
confi gure d to t ran smi t , to t he fi rst radi o st ati on , in fo r matio n abo ut a
r adio li nk p robl em o cc urri ng in a rad io l ink in the s econd cell b etw ee n
t he s econd r ad io sta t i on and th e radi o te rmin al whi le t he c arrier
15 aggre gat ion is bein g pe rfo rmed .
2. The radio communication system according to Claim 1,
wherein th e i nforma ti o n abou t the ra di o link problem incl ud es at l east
one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id ent if ie r , a
20 be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y
m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n.
3. The radio communication system according to Claim 1 or 2,
25 wherein th e probl em i nclud es at leas t on e of radio l i nk di s con necti on,
call d is con nection , a l oss of s ync hronization , re ce i ved qua lit y de gradat ion , and t hrou gh put d egrad atio n .
4. The radio communication s ystem according to any one of
30 Cl ai ms 1 t o 3 , whe r ei n th e info rmation about t he rad io li nk p r oblem
i ndicat es t hat th e p robl em is l ikel y t o oc cur or th at t he p rob lem h ad oc cu rr ed but has b ee n re co vered .
5. The radio communication system according to Claim 4,

41 wherein th e at least one o f t he s econd ra di o s tati on an d th e radio t ermin al d et ermin es that th e p ro bl em is li kel y to o ccu r b as ed on a m ovin g sp ee d o f th e r adi o t ermin al or an estim ati on result o f th e moving speed. 5
6. The radio communication system acc ording to any one of
Cl ai ms 1 t o 5 , whe r ei n th e r adi o t ermin al det ects t he prob lem an d
t r ansmits the i nforma t i on abou t th e ra dio link problem to th e f i rst
r adio sta ti on.
10
7. The radio communication system according to any one of
Cl ai ms 1 t o 6 , whe r ei n th e ra di o term inal d etects t he p r obl em and
t r ansmits t o t he fi rst rad io s t atio n a r equest fo r re con fi gura tion o f th e s econ d ce ll i ncl udin g th e in f orm ati on a bou t th e r adi o l ink p r oblem . 15
8. The radio communication system according to any one of
Cl ai ms 1 t o 5 , wherei n th e secon d r adio sta tion d ete cts t he p r obl em and t r ansmits the i nforma t i on abou t th e ra dio link problem to th e f i rst r adio sta ti on. 20
9. The radio communication system according to any one of
Cl ai ms 1 t o 8 , whe r ei n th e f irs t radio st ati on is c onfi gu r ed to re cei ve t he in fo r matio n ab out the ra di o link problem an d to c ont r ol commu nic ati on of the rad io te r m i nal in th e secon d c ell . 25
10. The radio communication system according to any one of
Cl ai ms 1 t o 9 , whe r ei n th e info rmation about t he rad io li nk p r ob lem
t r i ggers t he first radi o st ati on to p erform cont r ol to cope wit h the
problem.
30
11. The radio communication system according to Claim 10,
wherein th e con trol to cope wit h t he p ro bl em p erform ed b y th e fi rst
r adio sta ti on in clu des at le ast one of : con trol to r ecov er t he ra di o lin k of th e ra di o termi nal in th e se cond cell ; con trol to r el eas e th e ra di o

42 l i nk of th e radio t erm inal in th e sec ond cell, or c ontrol to es tab li sh a r adio li nk o f the r adi o t ermin al in a cel l d iff ere nt from th e secon d ce ll .
12. A fi rst r adi o stat ion t hat se r ve s a fi rs t cell , comp r is i ng:
5 commu nic ati on co ntrol means for su ppo rt ing car r ie r aggrega ti on
o f the first c el l an d a s eco nd c ell s erv ed b y a secon d ra di o st ati on, wherein
t he co mmun i cat ion control m ea ns p erfo rms , wit h a r adi o
t ermin al, r ad io resou rce cont ro l fo r t he firs t and secon d ce l l s in orde r
10 t o p erfo rm t he car ri er aggre ga tion i n th e radio t erm inal, an d
t he co mmun i cat ion control m ea ns recei ve s , from at l ea s t one o f
t he s econd r ad io sta t i on and th e radi o te rmin al , at le as t on e o f:
i nformat ion ab out a rad i o l ink p r oblem oc curring in a radio li nk in th e
s econ d ce ll b etween the second r adio st atio n and th e radi o te rm in al
15 while t he car ri er aggre ga tion i s bei ng per fo r med ; and radio li nk st atu s
i nformat ion ind icatin g t hat t he pr ob lem has b een det ected in th e radio link.
13. Th e f irs t radio st ati on a cc ordin g to Claim 12 , w herei n th e
20 i nformat ion ab out the r adio lin k pro blem i ncl udes at l ea st on e of
t r i gger i nformati on, a t erm inal id ent ifi er, a c ell identi fi er, a beare r i dent if ie r , a dat a tra ns m i ssio n/re cept ion sta tu s , ra dio qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n. 25
14. Th e f irs t radio st ati on a cc ordin g to Claim 12 o r 13 , w he r ein
t he pro blem in clu de s at l east o ne of r ad i o li nk di s con nect ion , c all
di s con ne cti o n, a l os s of s yn ch r onization , re ce i ved q ual it y d egra da t ion , and th r ough put degrada tion . 30
15. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o
14, wher ein th e info rm at ion abo ut t he r adio lin k pro bl em in dicat es t hat
t he pro blem is lik el y to o cc ur or t ha t t he p ro blem h ad o ccurre d b ut ha s
be en recover ed .

43
16. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o
15, wher ein th e co mmun i cati on c ontrol m ea ns recei ve s from th e radio
t ermin al a requ es t f or re confi gurat ion of th e secon d cell i ncl uding t he
5 i nformat ion ab out the r adio lin k pro blem .
17. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o
16, wher ein th e co mmun i cati on c ontrol m ea ns recei ve s the i nformat ion
about t he radio l ink prob lem and con t rol s co mmuni cat ion of th e rad i o
10 t ermin al i n t he se cond cell .
18. Th e f irs t radio st ati on a cc ordin g to an y o ne o f C lai ms 1 2 t o
17, wher ein th e info rm at ion abo ut t he r adio lin k pro bl em tri ggers th e
fi rst rad io st ati on to p erform con t ro l t o co pe w i th th e prob lem .
15
19. Th e f irs t radio st ati on a cc ordin g to Claim 18 , w herei n th e
cont ro l to cope with t he p r ob lem p erformed b y t he fi r s t r adio sta ti on
i nclu des at least o ne of : con t ro l to r ecov er t he r ad io li nk of the r adio
t ermin al in th e s ec ond cell ; co ntrol t o r eleas e t he r ad io lin k of t he
20 r adio t erminal in th e secon d ce ll ; or c on trol to e stablish a ra dio link of
t he rad io t e rmi nal in a cell di fferent from th e s ec ond cell.
20. A s eco nd radi o s tatio n tha t se r ve s a se cond cel l , comp ri si ng:
commu nic ati on co nt rol me ans for su ppo rtin g ca r r i er aggr ega t ion
25 o f a fi rst cel l served b y a fi rst r adio stat ion an d th e s econ d c ell ,
wherein
t he co mmun i cat ion control m ea ns t ransmit s , to t he first radio
st at ion , i nforma tio n abou t a ra di o lin k probl em oc cu r rin g in a r adi o
l i nk i n th e se cond cell b etw een t he se cond r adio s tat ion a nd a rad io
30 t ermin al while t he car ri er aggre gat i on is bei ng perfo rm ed b y th e ra di o
t ermin al.
21. Th e s ec ond radio st ati on a cc ord in g t o Claim 20 , wh erei n the
i nformat ion ab out the r adio lin k pro b lem i ncl udes at l ea st on e of

44 t r i gger i nformati on, a t erm inal id ent ifi er, a c ell identi fi er, a beare r i dent if ie r , a dat a tra ns m i ssio n/re cept ion sta tu s , ra dio qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm ati on. 5
22. Th e s ec ond radio st ati on a cc ord in g t o Claim 20 o r 21 ,
wherein th e probl em i nclud es at leas t on e of radio l i nk di s con necti on,
call d is con nection , a l oss of s ync hronization , re ce i ved qua lit y
de gradat ion , and t hrou gh put d egrad atio n . 10
23. Th e s ec ond ra di o st ati on acco rd in g to an y o ne of C laim s 20
t o 2 2, wh erein th e in form atio n abou t th e r adi o li nk p r oblem indi ca tes
t hat th e pro bl em i s lik el y to occu r or th at th e probl em had oc curred but has b een r ecov ere d. 15
24. Th e s ec ond radio st ati on a cc ord in g t o Cl aim 23 , w he r ei n the
commu nic ati on co ntrol means d et e rmin es th at t he p r oblem is l i kel y t o
oc cu r base d on a mo vin g speed of t he radio t erm ina l o r a n est ima tion
r esu lt of t h e m ovi ng s peed. 20
25. Th e s ec ond radio st ati on a cc ord in g t o an y o ne o f C laim s 2 0
t o 24, wh erei n th e in fo r m atio n ab out th e r adi o li nk p r oblem trigge r s
t he first radio st ation to p erfo r m c ontrol t o co pe with th e prob lem.
25 26. Th e s ec ond radio st ati on a cc ord in g t o Claim 25 , wh erei n the
cont ro l to cope with t he p r ob lem p erformed b y t he fi r s t radi o st ation i nclu des at least o ne of : con t ro l to r ecov er t he r ad io li nk of the r adio t ermin al in th e s ec ond cell ; co nt rol t o r eleas e t he r ad io lin k of t he r adio t erminal in th e secon d ce ll ; or c on trol to e stablish a ra dio link of
30 t he rad io t e rmi nal in a c ell di ff eren t from t he s econd c ell.
27. A r adi o t ermin al c om prisin g:
commu nic ati on co ntrol means for su ppo rt ing car r ie r aggrega ti on o f a fi rst cel l served b y a fi rst r adio stat ion an d a se cond cel l s erv ed

45 b y a s ec ond rad io stat io n, wh erein
t he co mmun i cat io n co ntrol mean s p erforms , wit h t he fi r st rad io
st at ion , r adio r es ou rce co ntrol for th e fi rst and s econd cel ls in o r de r to
pe rform t he carrie r aggr ega ti on, and
5 t he co mmun i cat ion control m ea ns t ransmit s , to t he first radio
st at ion , at leas t on e o f : i n fo rm ation abo ut a rad io l ink problem
oc cu rr ing i n a rad io link i n t he secon d cell b et we en t he se cond r adio
st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s bei ng
pe rform ed; and radio link st atu s info rm ation i ndi cat in g tha t t he
10 problem h as b e e n d ete cted i n th e radio l i nk.
28. Th e r ad i o t erm inal accordin g t o Cl aim 27, wh ere i n t he
i nformat ion ab out the r adio lin k pro blem i ncl udes at l ea st on e of
t r i gger i nformati on, a t erm inal id ent ifi er, a c ell identi fi er, a beare r
15 i dent if ie r , a dat a tra ns m i s sio n/ recept ion st atu s , radi o qu ali t y
m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n.
29. Th e r ad i o t erm inal accordin g t o Cl aim 27 o r 2 8, wherein th e
20 problem inc lu des at l east on e o f rad io lin k di s con nect ion , call
di s con ne cti o n, a l os s of s yn ch r onization , re ce i ved q ual it y d egra da t ion , and th r ough put degrada tion .
30. Th e r ad i o t erm inal accordin g t o an y o ne of C lai m s 27 t o 29 ,
25 wherein th e i nforma ti o n abou t the ra di o link problem indi ca tes t hat t he
problem is l ikel y t o oc cur or tha t th e probl em had occu rr ed but h as be en recover ed .
31. Th e r ad i o t erm inal accordin g t o Cl aim 30, wh ere i n t he
30 commu nic ati on co ntrol means d et e rmin es th at t he p r oblem is l i kel y t o
oc cu r base d on a mo vin g speed of t he radio t erm ina l o r an estim ation r esu lt of t h e m ovi ng s peed.
32. Th e r ad i o t erm inal accordin g t o an y o ne of C lai m s 27 t o 31 ,

46 wherein th e comm uni cat io n co ntrol mean s t r an sm its to t he firs t r adio st at ion a req uest for r ec onfigu r ati on o f t he s econd cell i ncl uding t he i nformat ion abo ut the r adio lin k pro blem .
5 33. Th e r ad i o t erm inal accordin g t o an y o ne of C lai m s 27 t o 32 ,
wherein th e i nforma ti o n abou t the ra di o link problem trigge r s the fi r st r adio sta ti on t o per f or m cont rol to cope wi th t he p r obl em .
34. Th e r ad i o t erm inal ac co rdin g to C l aim 3 3, wherein th e
10 cont ro l to cope with t he p r ob lem p erformed b y t he fi r s t r adio sta ti on
i nclu des at least o ne of : con t ro l to r ecov er t he r ad io li nk of the r adio t ermin al in th e s ec ond cell ; co nt rol t o r eleas e t he r ad io lin k of t he r adio t e rmin al in t he s ec ond cell ; or c on trol to e stablish a ra dio link of t he rad io t e rmi nal in a cell di fferent from th e s ec ond cell.
15
35. A com municati on c ontrol m ethod in a fi rs t r adi o st atio n th at
s erv es a first c el l, t he met hod co mprisi ng:
performi ng , w i t h a r adio te r min al , ra dio resou r ce co ntrol fo r th e
fi rst cell a nd a se con d cell se rv ed b y a s econd ra di o s ta tion i n ord er to
20 pe rform carrier ag gregat ion o f the firs t an d secon d c el l s; and
r ecei vin g, from at lea st on e o f th e secon d radio st atio n and t he
r adi o t ermin al , at least one o f: i nformati on a bout a r adio lin k prob l em
oc cu rr ing i n a rad io link i n t he secon d cell b et we en t he se cond r adio
st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s b ein g
25 pe rform ed ; and r adio li nk st atu s in f orm atio n i n di cat in g tha t t he
problem h as b ee n d ete cted i n th e radio l i nk.
36. The communication control method according to Claim 35,
wherein th e i nforma ti o n abou t the ra di o link problem incl ud es at l ea st
30 one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id entifi er, a
be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermin al lo cati on in fo rm atio n.

47
37. The communication control method according to Claim 35 or
36, wher ein th e p robl em i ncl ud es at least one o f ra dio link
di s con ne cti o n, call disco nn ecti on, a lo ss of s yn ch r oniz atio n , receiv ed quali t y d egrad at ion , and th ro ugh put d egra datio n . 5
38. The communication control method according to any one of
Cl ai ms 3 5 t o 37, w he r ei n th e in fo rm atio n abo ut th e r adi o li nk p ro bl em
i ndicat es t hat th e p robl em is l ikel y t o oc cur or th at t he p rob lem h ad
oc cu rr ed but has b ee n re co vered .
10
39. The communication control method according to any one of Cl ai ms 3 5 t o 38, fu rt her com pris i ng p erformin g c ont rol to c op e wit h t he pro blem .
40. The communication control method according to Claim 39, wherein th e con trol to cope wit h t he p ro bl em p erform ed b y th e fi rst r adio sta ti on in clu des at le ast one of : con trol to r ecov er t he ra di o lin k of th e ra di o termi nal in th e se cond cell ; con trol to r el eas e th e ra di o l i nk of th e radio t erm inal in th e sec ond cell ; or co nt rol t o est ablish a r adio li nk o f the r adi o t ermin al in a cel l d iff ere nt from th e secon d ce ll .
41. A com municati on c ontrol m ethod in a se cond ra dio s tati on t hat s erv es a second cell, th e m eth od com pri si ng:
commu nic ati ng with a radio te rm in al in c arrier a ggregatio n o f a
25 fi rst cell s erved by a f irst radio st at io n an d th e se cond cell; and
t ransmitt ing , to t he fi r st rad io s tat i on , in f or m atio n ab out a r a dio l i nk pro blem o ccurrin g in a radio l ink in th e seco nd c el l bet we en the s econ d r adi o station and th e r ad io t ermin al w hil e th e carrier aggre gat ion is bein g pe rfo rmed . 30
42. The communication control method according to Claim 41,
wherein th e i nforma ti o n ab o ut the ra di o link problem incl ud es at l ea st
one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id ent if ie r , a
be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y

48 m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , and t ermi nal lo cat ion in fo r matio n.
43. The communication control method according to Claim 41 or
5 42, wher ein th e prob lem in clu des at le ast one of r adio lin k
di s con ne cti o n, call disco nn ecti on, a lo ss of s yn ch r oniz atio n , receiv ed quali t y d egrad at ion , and th ro ugh pu t d egra datio n .
44. A com municati on c ontrol m ethod in a ra di o te rm inal , th e
10 method comprising:
performi ng , w i t h a firs t radio st at ion , r adi o res ourc e co ntrol fo r a fi rst cell served b y th e firs t radio stati on a nd a s econ d cell ser ve d b y a seco nd rad io st atio n in o rder t o pe rfo rm ca rri er aggre ga ti on o f t he fi rst and s eco nd c ells; an d
15 t ransmitt ing , to t he fi r st rad io s tat i on , at l east on e o f :
i nformat ion ab out a rad i o l ink p r oblem oc curring in a radio li nk in th e s econ d ce ll b etween the second r adio st atio n a nd the r adi o t ermin al while t he car ri er aggre ga tion is bein g pe r fo rm ed; and radi o link status i nformat ion ind icatin g t hat t he prob lem has b een det ected in th e radio
20 l i nk.
45. The communication control method according to Claim 44,
wherein th e i nforma t io n abou t the ra di o link problem incl ud es at l ea st
one o f tri gger in fo rm ation , a t erm inal i de nt ifier , a cel l id ent if ie r , a
25 be arer ide nt ifier , a d at a t ransmissi on/ r ec ept io n st atu s , rad io qu alit y
m easu reme nt i nforma ti on, ter min al movi ng s peed in fo rmation , an d t ermin al lo cati on in fo rm atio n.
46. The communication control method according to Claim 44 or
30 45, wher ein th e prob lem in clu des at le ast one of r adio lin k
di s con ne cti o n, call disco nn ecti on, a lo ss of s yn ch r oniz atio n , receiv ed quali t y d egrad at ion , and th r ou ghput d egra datio n .
47. A non -tra nsit or y co m put er re adabl e me dium s tori ng a

49 program for causing a computer to perform a communication control m etho d in a first ra di o st ati on that s erv es a f irst cell , wherein the communication control method comprises:
performi ng , w i t h a rad io t ermi nal , ra dio resou r ce co ntrol fo r th e
5 fi rst cell a nd a se con d cell se rv ed b y a s econd ra di o s ta tion t o pe r f orm
ca rrier aggre gat ion o f t he first and secon d c el l s; and
r ecei vin g, from at lea st on e o f th e secon d radio st atio n an d th e
r adio t erminal , at least one o f: i nformati on a bout a r adio lin k prob l em
oc cu rr ing i n a rad io link i n t he secon d cell b et we en t he se cond r adio
10 st at ion and th e r ad io t ermi nal wh il e t he c arrier a ggregatio n i s b ein g
pe rform ed; and r adio li nk st atu s in f or mat ion ind ic ating th at th e problem h as b ee n d ete cted i n th e radio l i nk.
48. A non -tra nsit or y co m put er re adabl e me dium s tori ng a program for causing a computer to perform a communication control m etho d in a s econ d r adio st atio n th at se rv es a se cond cell, wh erei n
the communication control method comprises:
commu nic ati ng with a radio st at i on i n ca r ri er aggre gat ion of a fi rst cell s erved by a f irst radio st at io n an d th e se cond cell; and
t ransmitt ing , to t he fi r st rad io s tat i on , in f or m atio n ab out a radio l i nk pro blem o ccurrin g in a radio l ink in th e seco nd c el l bet we en the s econ d r adi o station and th e r ad io t ermin al w hil e th e carrier aggre gat ion is bein g pe rfo rmed .
25 49. A non -tra nsit or y co m put er re adabl e me dium s tori ng a
program for causing a computer to perform a communication control
m etho d in a rad io te r m i nal , w he rei n
the communication control method comprises:
performi ng , w i t h a firs t radio st at ion , r adi o res ourc e co ntrol fo r
30 a fi rst cell served b y th e firs t radio stati on a nd a s econ d cell ser ve d b y
a s eco nd rad io st atio n in o rder t o pe rfo rm ca rri er aggre ga ti on o f t he
fi rst and s eco nd c ells; an d
t ransmitt ing , to t he fi r st rad io s tat i on , at l east on e o f :
i nformat ion ab out a rad i o l ink p r oblem oc curring in a radio li nk in th e

50 second cell between the second radio station and the radio terminal while the carrier aggregation is being performed; and radio link status information indicating that the problem has been detected in the radio link.