Allocating a control channel for carrier aggregation

• US 8,626,218 B2
• Filed: 12/14/2010
• Issued: 01/07/2014
• Est. Priority Date: 05/03/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Wang, Ping
• Primary Examiner(s): Safaipour, Bobbak
• Application Number:
  US12/967,652
• Publication Number:
  US 20110269492A1
• Time in Patent Office: 1,120 Days
• Field of Search: 370/328, 370/329, 370/252, 370/241, 455/522, 455/422, 455/414, 455/407, 455/509
• US Class Current: 455/509
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/12 using signalling between network elements
• CPC Class Codes: H04W 36/22 for handling the traffic
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 : in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/52 : based on load
• CPC Class Codes: H04W 76/27 : Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 8/04 : Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: Y02D 30/00 : Reducing energy consumption in communication networks
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

Methods for allocating a physical downlink control channel (PDCCH) to reduce a number of PDCCH candidates in a search space for carrier aggregation on a user equipment (UE) are disclosed. The method comprises the step of selecting a control channel element (CCE) aggregation level for a PDCCH allocation for each of a plurality of user equipments (UEs) at an evolved NodeB (eNB). The operation of identifying a transmission mode for each of a plurality of component carriers (CCs) associated with the PDCCH at the eNB follows. The next operation of the method is assigning each CC'"'"'s downlink control information (DCI) into CCEs in a PDCCH search space in the PDCCH starting at a CCE location based on the CC'"'"'s transmission mode and the CCE aggregation level for the UE receiving the CC.

Claims

1. A method for determining physical downlink control channel (PDCCH) assignments in a long term evolution (LTE) communication system, comprising:

monitoring by a user equipment (UE) a set of PDCCH candidates, the set of PDCCH candidates to monitor defined in a search space S_k^(L) at an aggregation level Lε

{1,2,4,8} for a sub frame k;

wherein if the UE is configured with a carrier indicator field (CIF), the UE monitors one or more UE-specific search spaces at each of aggregation levels 1, 2, 4, 8, and wherein if the UE is not configured with the CIF, the UE monitors a common search space;

wherein if the UE is configured to monitor PDCCH candidates with a given downlink control information (DCI) format size with the CIF and if the PDCCH candidates may have one or more possible values of CIF for a given DCI format size, the UE monitors PDCCH candidates with the given DCI format size in UE-specific search spaces corresponding to possible values of the CIF for the given DCI format size; and

wherein the given DCI format that the UE is configured to monitor uses a configured transmission mode.

2. The method of claim 1, wherein the search space S_k^(L) uses a carrier index CI to monitor the set of PDCCH candidates, wherein the carrier index CI includes a CIF value or an index of a sorted CIF value.

3. The method of claim 1, wherein the search space S_k^(L) is represented by S_k^(L)=L·

{(Y_k +m)mod└

N_CCE,k/L┘

}+i;

where the search space S_k^(L) uses the configured transmission mode to monitor the set of PDCCH candidates;

Y_k is a variable;

m=0, . . ., M^(L)−

1, and M^(L) is the number of PDCCH candidates to monitor in the search space;

N_CCE,k is the total number of control channel elements (CCEs) in a kth subframe where Kε

{0,1,2,3,4,5,6,7,8,9}; and

i=0, . . ., L−

1 is an increment integer.

4. The method of claim 3, wherein variable Y_k is represented by Y_k =[A·

(Y_k-1+ƒ

(T_c,m))]mod D ;

where A=39827,Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(T_c,m) is a function using the configured transmission mode T_c,m for a carrier c.

5. The method of claim 3, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m)) is a function using the configured transmission mode T_c,m for a carrier c and a carrier index CI in a DCI format.

6. The method of claim 3, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m,S))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m,S) is a function using the configured transmission mode T_c,m for a carrier c, a carrier index CI in a DCI format, and the DCI format size S.

7. The method of claim 1, wherein monitoring the set of PDCCH candidates further comprises:

receiving the PDCCH at the UE;

searching for a selected component carrier'"'"'s (CC'"'"'s) downlink control information (DCI) in the search space S_k^(L) by identifying a starting control channel elements (CCE) location based on a selected CC'"'"'s carrier index and the aggregation level L for the UE receiving the selected CC, wherein the carrier index includes a CIF value or an index of a sorted CIF value;

decoding each PDCCH candidate in the search space S_k^(L) beginning at the starting CCE location until a validly decoded PDCCH candidate is decoded; and

obtaining the selected CC'"'"'s DCI from the validly decoded PDCCH candidate.

8. The method of claim 1, wherein monitoring the set of PDCCH candidates further comprises recursively searching the search space S_k^(L) at a different aggregation level L until a validly decoded PDCCH candidate is decoded.

9. An apparatus, comprising:

a communications processor for a user equipment (UE) operative to determine physical downlink control channel (PDCCH) assignments in a long term evolution (LTE) communication system by monitoring by a user equipment (UE) a set of PDCCH candidates, the set of PDCCH candidates to monitor defined in a search space S_k^(L) at an aggregation level Lε

{1,2,4,8} for a subframe k;

wherein if the UE is configured with a carrier indicator field (CIF), the UE monitors one or more UE-specific search spaces at each of aggregation levels 1, 2, 4, 8; and

wherein the UE monitors the set of PDCCH candidates using a configured transmission mode for the UE.

10. The apparatus of claim 9, wherein if the UE is not configured with the CIF, the UE monitors a common search space;

wherein if the UE is configured to monitor PDCCH candidates with a given downlink control information (DCI) format size with the CIF and if the PDCCH candidates may have one or more possible values of CIF for a given DCI format size, the UE monitors PDCCH candidates with the given DCI format size in UE-specific search spaces corresponding to possible values of the CIF for the given DCI format size; and

wherein the given DCI format that the UE is configured to monitor uses a configured transmission mode.

11. The apparatus of claim 9, wherein the search space S_k^(L) uses a carrier index CI to monitor the set of PDCCH candidates, wherein the carrier index CI includes a CIF value or an index of a sorted CIF value.

12. The apparatus of claim 9, wherein the search space S_k^(L) is represented by S_k^(L)=L·

{(Y_k+m)mod└

N_CCE,k/L┘

}+i;

where the search space S_k^(L) uses the configured transmission mode to monitor the set of PDCCH candidates;

Y_k is a variable;

m=0, . . ., M^(L)−

1, and M^(L) is the number of PDCCH candidates to monitor in the search space;

N_CCE,k is the total number of control channel elements (CCEs) in a kth subframe where kε

{0,1,2,3,4,5,6,7,8,9}; and

i=0, . . ., L−

1 is an increment integer.

13. The apparatus of claim 12, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(T_c,m))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(T_c,m) is a function using the configured transmission mode T_c,m for a carrier c.

14. The apparatus of claim 12, wherein variable Y_k is represented by Y_k=[A≠

(Y_k-1+ƒ

(CI,T_c,m))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m) is a function using the configured transmission mode T_c,m for a carrier c and a carrier index CI in a DCI format.

15. The apparatus of claim 12, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m,S))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m ,S) is a function using the configured transmission mode T_c,m for a carrier c, a carrier index CI in a DCI format, and the DCI format size S.

16. The apparatus of claim 9, wherein monitoring the set of PDCCH candidates further comprises:

receiving the PDCCH at the UE;

searching for a selected component carrier'"'"'s (CC'"'"'s) downlink control information (DCI) in the search space S_k^(L) by identifying a starting control channel elements (CCE) location based on a selected CC'"'"'s carrier index and the aggregation level L for the UE receiving the selected CC, wherein the carrier index includes a CIF value or an index of a sorted CIF value;

decoding each PDCCH candidate in the search space S_k^(L) beginning at the starting CCE location until a validly decoded PDCCH candidate is decoded; and

obtaining the selected CC'"'"'s DCI from the validly decoded PDCCH candidate.

17. A mobile device, comprising:

a user equipment (UE) operable in a long term evolution (LTE) communication system to monitor a set of PDCCH candidates, the set of PDCCH candidates to monitor defined in a search space S_k^(L) at an aggregation level Lε

{1,2,4,8} for a subframe k;

wherein the search space S_k^(L) uses a carrier index CI to monitor the set of PDCCH candidates, wherein the carrier index CI includes a CIF value or an index of a sorted CIF value; and

wherein the UE monitors the set of PDCCH candidates using a configured transmission mode for the UE.

18. The mobile device of claim 17, wherein if the UE is configured with a carrier indicator field (CIF), the UE monitors one or more UE-specific search spaces at each of aggregation levels 1, 2, 4, 8, and wherein if the UE is not configured with the CIF, the UE monitors a common search space;

wherein if the UE is configured to monitor PDCCH candidates with a given downlink control information (DCI) format size with the CIF and if the PDCCH candidates may have one or more possible values of CIF for a given DCI format size, the UE monitors PDCCH candidates with the given DCI format size in UE-specific search spaces corresponding to possible values of the CIF for the given DCI format size; and

wherein the given DCI format that the UE is configured to monitor uses a configured transmission mode.

19. The mobile device of claim 17, wherein the search space S_k^(L) is represented by S_k^(L)=L·

{(Y_k+m)mod└

N_CCE,k/L┘

}+i;

where the search space S_k^(L) uses the configured transmission mode to monitor the set of PDCCH candidates;

Y_k is a variable;

m=0, . . ., M^(L)−

1 ,and M^(L)is the number of PDCCH candidates to monitor in the search space;

N_CCE,k is the total number of control channel elements (CCEs) in a kth subframe where kε

{0,1,2,3,4,5,6,7,8,9}; and

i=0, . . ., L−

1 is an increment integer.

20. The mobile device of claim 19, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(T_c,m))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(T_c,m) is a function using the configured transmission mode T_c,m for a carrier c.

21. The mobile device of claim 19, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m))]mod D ;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m) is a function using the configured transmission mode T_c,m for a carrier c and a carrier index CI in a DCI format.

22. The mobile device of claim 19, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m,S))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m,S) is a function using the configured transmission mode T_c,m for a carrier c, a carrier index CI in a DCI format, and the DCI format size S.

23. The mobile device of claim 17, wherein the UE monitors the set of PDCCH candidates by:

receiving the PDCCH at the UE;

searching for a selected component carrier'"'"'s (CC'"'"'s) downlink control information (DCI) in the search space S_k^(L) by identifying a starting control channel elements (CCE) location based on a selected CC'"'"'s carrier index and the aggregation level L for the UE receiving the selected CC, wherein the carrier index includes a CIF value or an index of a sorted CIF value;

decoding each PDCCH candidate in the search space S_k^(L) beginning at the starting CCE location until a validly decoded PDCCH candidate is decoded; and

obtaining the selected CC'"'"'s DCI from the validly decoded PDCCH candidate.

24. A base transceiver station (BTS), comprising:

an evolved Node B (eNB) operable in a long term evolution (LTE) communication system to assign a set of PDCCH candidates, the set of PDCCH candidates to assign defined in a search space S_k^(L) at an aggregation level Lε

{1,2,4,8} for a subframe k;

wherein the eNB is operable to communicate with a radio network controller (RNC) and a user equipment (UE) in a universal terrestrial radio access network (UTRAN);

wherein the BTS configures the UE with a carrier indicator field (CIF) when the UE is to monitor one or more UE-specific search spaces; and

wherein the UE assigns the set of PDCCH candidates using a configured transmission mode for the UE.

25. The BTS of claim 24, wherein the BTS does configure the UE with a carrier indicator field (CIF) when the UE is to monitor a common search space;

wherein if the UE is configured to monitor PDCCH candidates with a given downlink control information (DCI) format size with the CIF and if the PDCCH candidates may have one or more possible values of CIF for a given DCI format size, the BTS assigns a PDCCH with the given DCI format size in the UE-specific search space corresponding to the CIF for the given DCI format size; and

wherein the given DCI format that the UE is configured to monitor uses a configured transmission mode.

26. The BTS of claim 24, wherein the search space S_k^(L) uses a carrier index CI to monitor the set of PDCCH candidates, wherein the carrier index CI includes a CIF value or an index of a sorted CIF value.

27. The BTS of claim 24, wherein the search space S_k^(L) is represented by S_k^(L)=L·

{(Y_k+m)mod└

N_CCE,k/L┘

}+i;

where the search space S_k^(L) uses the configured transmission mode to monitor the set of PDCCH candidates;

Y_k is a variable;

m=0, . . ., M^(L)−

1, and M^(L) is the number of PDCCH candidates to monitor in the search space;

N_CCE,k is the total number of control channel elements (CCEs) in a kth subframe where kε

{0,1,2,3,4,5,6,7,8,9}; and

i=0, . . ., L−

1 is an increment integer.

28. The BTS of claim 27, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(T_c,m))]mod D;

where A=39827,Y<sub>−

1</sub>=n_RNHTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s2┘

where n_s is a slot number within a radio frame; and

ƒ

(T_c,m) is a function using the configured transmission mode T_c,m, for a carrier c.

29. The BTS of claim 27, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m))]mod D ;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m) is a function using the configured transmission mode T_c,m for a carrier c and a carrier index CI in a DCI format.

30. The BTS of claim 27, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m,S))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m,S) is a function using the configured transmission mode T_c,m for a carrier c, a carrier index CI in a DCI format, and the DCI format size S.

31. The BTS of claim 24, wherein the BTS assigns the set of PDCCH candidates by:

selecting the aggregation level L for a PDCCH allocation for each of a plurality of user equipments (UEs);

identifying the carrier index for each of a plurality of component carriers (CCs) associated with the PDCCH, wherein the carrier index includes a CIF value or an index of a sorted CIF value; and

assigning each CC'"'"'s downlink control information (DCI) into control channel elements (CCEs) in the search space S_k^(L) in the PDCCH at a control channel element (CCE) starting location that is selected based on the CC'"'"'s carrier index and the aggregation level L for the UE receiving the CC.

32. The BTS of claim 31, wherein assigning each CC'"'"'s DCI into CCEs further comprises:

assigning the CCEs of the CCs with a first carrier index CI₁ into a first carrier index search space S_k^(L) (CI₁) with a first carrier index CI₁ starting CCE location; and

assigning the CCEs of the CCs with a second carrier index CI₂ into a second carrier index search space S_k^(L) (CI₂) with a second carrier index CI₂ starting CCE location that differs from the first carrier index CI₁ starting CCE location, wherein first carrier index search space S_k^(L) (CI₁) and the second carrier index search space S_k^(L) (CI₂) are subsets of S_k^(L).

33. A computer program product, comprising a non-transitory computer readable storage medium having a computer readable program code embodied therein, the computer readable program code adapted to be executed to implement a method for determining physical downlink control channel (PDCCH) assignments in a long term evolution (LTE) communication system, comprising:

monitoring by a user equipment (UE) a set of PDCCH candidates, the set of PDCCH candidates to monitor defined in a search space S_k^(L) at an aggregation level Lε

{1,2,4,8} for a subframe k;

wherein if the UE is configured with a carrier indicator field (CIF), the UE monitors one or more UE-specific search spaces at each of aggregation levels 1, 2, 4, 8; and

wherein the UE monitors the set of PDCCH candidates using a configured transmission mode for the UE.

34. The computer program product of claim 33, wherein if the UE is not configured with the CIF, the UE monitors a common search space;

wherein if the UE is configured to monitor PDCCH candidates with a given downlink control information (DCI) format size with the CIF and if the PDCCH candidates may have one or more possible values of CIF for a given DCI format size, the UE monitors PDCCH candidates with the given DCI format size in UE-specific search spaces corresponding to possible values of the CIF for the given DCI format size; and

wherein the given DCI format that the UE is configured to monitor uses a configured transmission mode.

35. The computer program product of claim 33, wherein the search space S_k^(L) uses a carrier index CI to monitor the set of PDCCH candidates, wherein the carrier index CI includes a CIF value or an index of a sorted CIF value.

36. The computer program product of claim 33, wherein the search space S_k^(L) is represented by S_k^(L)=L·

{(Y_k+m)mod└

N_CCE,k/L┘

}+i;

where the search space S_k^(L) uses the configured transmission mode to monitor the set of PDCCH candidates;

Y_k is a variable;

m=0, . . ., M^(L)−

1 and M^(L) is the number of PDCCH candidates to monitor in the search space;

N_CCE,k is the total number of control channel elements (CCEs) in a kth subframe where kε

{0,1,2,3,4,5,6,7,8,9}; and

i=0, . . ., L−

1 is an increment integer.

37. The computer program product of claim 36, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(T_c,m))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(T_c,m) is a function using the configured transmission mode T_c,m for a carrier c.

38. The computer program product of claim 36, wherein variable Y_k is represented by Y_k =[A·

(Y_k-1+ƒ

(CI,T_c,m))]mod D ;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m) is a function using the configured transmission mode T_c,m for a carrier c and a carrier index CI in a DCI format.

39. The computer program product of claim 36, wherein variable Y_k is represented by Y_k=[A·

(Y_k-1+ƒ

(CI,T_c,m,S))]mod D;

where A=39827, Y<sub>−

1</sub>=n_RNTI≠

0, and D=65537 are constant where n_RNTI is a radio network temporary identifier (RNTI) assigned to the UE by an evolved Node B (eNB);

k is an integer k=└

n_s/2┘

where n_s is a slot number within a radio frame; and

ƒ

(CI,T_c,m,S) is a function using the configured transmission mode T_c,m for a carrier c, a carrier index CI in a DCI format, and the DCI format size S.

40. The computer program product of claim 33, wherein monitoring the set of PDCCH candidates further comprises:

receiving the PDCCH at the UE;

searching for a selected component carrier'"'"'s (CC'"'"'s) downlink control information (DCI) in the search space s_k^(L) by identifying a starting control channel elements (CCE) location based on a selected CC'"'"'s carrier index and the aggregation level L for the UE receiving the selected CC, wherein the carrier index includes a CIF value or an index of a sorted CIF value;

decoding each PDCCH candidate in the search space S_k^(L) beginning at the starting CCE location until a validly decoded PDCCH candidate is decoded; and

obtaining the selected CC'"'"'s DCI from the validly decoded PDCCH candidate.

41. The computer program product of claim 33, wherein monitoring the set of PDCCH candidates further comprises recursively searching the search space S_k^(L) at a different aggregation level L until a validly decoded PDCCH candidate is decoded.