Monitoring a control channel for carrier aggregation

1. An apparatus, comprising:

a user equipment (UE) configured with a carrier information field (CIF) and having a communications processor to determine physical downlink control channel (PDCCH) assignments of a cellular communication system, wherein the communication processor is to monitor in a cell a set of PDCCH candidates defined in a search space S k (L) at an aggregation level Lε{1,2,4,8} for a subframe (k) which includes a set of control channel elements (CCEs) and to decode a PDCCH of the set of PDCCH candidates according to downlink control information (DCI).

2. The apparatus of claim 1 , wherein the search space S k (L) is defined by S k (L) =L·{(Y k +m)mod └N CCE,k /L┘}+i wherein N CCE,k is the total number of CCEs in a k th subframe (kε{0,1,2,3,4,5,6,7,8,9}), i=0, . . . , L−1 is a constant, m=0, . . . , M (L) −1, and M (L) is the number of PDCCH candidates to monitor in a given search space.

3. The apparatus of claim 2 , wherein Y k is defined by Y k =(A·Y k-1 )mod D wherein, Y k-1 =n RNTI ≠0, n RNTI ≠0, n RNTI is a Radio Network Temporary Identifier (RNTI) number assigned to the UE, A=39827, D=65537, k=└n s /2┘, and n s (nε{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}) is the slot number within a radio frame.

4. The apparatus of claim 1 , wherein the communication processor is programmed to:

search 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 until a validly decoded PDCCH candidate is decoded; and

to obtain the selected CC's DCI from the validly decoded PDCCH candidate.

5. The apparatus of claim 1 , wherein a PDCCH candidate includes a cyclic redundancy check (CRC) which is masked by a Cell-Radio Network Temporary Identifier (C-RNTI).

6. The apparatus of claim 1 , wherein the DCI format includes the CIF.

7. A method for monitoring physical downlink control channel (PDCCH) assignments by a user equipment (UE) configured with a carrier information field (CIF) and, the method comprising:

monitoring in a cell a set of PDCCH candidates defined in a search space S k (L) at an aggregation level Lε{1,2,4,8} for a subframe (k) which includes a set of control channel elements (CCEs) and to decode a PDCCH of the set of PDCCH candidates according to downlink control information (DCI).

8. The method of claim 7 , wherein the search space S k (L) is defined by S k (L) =L·{(Y k +m)mod └N CCE,k /L┘}+i wherein N CCE,k is the total number of CCEs in a k th subframe (kε{0,1,2,3,4,5,6,7,8,9}), i=0, . . . , L−1 is a constant, m=0, . . . , M (L) −1, and M (L) is the number of PDCCH candidates to monitor in a given search space.

9. The method of claim 8 , wherein Y k is defined by Y k =(A·Y k-1 )mod D wherein, Y k-1 =n RNTI ≠0, n RNTI is a Radio Network Temporary Identifier (RNTI) number assigned to the UE, A=39827, D=65537, k=└n s /2┘, and n s (nε{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}) is the slot number within a radio frame.

10. The method of claim 7 , wherein monitoring comprising:

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 until a validly decoded PDCCH candidate is decoded; and

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

11. The method of claim 10 , wherein a PDCCH candidate includes a cyclic redundancy check (CRC) which is masked by a Cell-Radio Network Temporary Identifier (C-RNTI).

12. The method of claim 11 , wherein the DCI format includes the CIF.

13. A communication system, comprising:

an evolved Node B (eNB) configured with a carrier information field (CIF) operable in a long term evolution (LTE) communication system comprises a transmitter operably coupled to one or more antenna ports and capable of assigning a set of PDCCH candidates to a user equipment (UE), the set of PDCCH candidates are defined in a search space S k (L) at an aggregation level Lε{1,2,4,8} for a subframe k which includes a set of control channel elements (CCEs) and wherein, the UE is configured to monitor the set of PDCCH and to decode a PDCCH of the set of PDCCH candidates according to downlink control information (DCI).

14. The communication system of claim 13 , wherein the search space S k (L) is defined by S k (L) =L·{(Y k +m)mod └N CCE,k /L┘}+i wherein N CCE,k is the total number of CCEs in a k th subframe (kε{0,1,2,3,4,5,6,7,8,9}), i=0, . . . , L−1 is a constant, m=0, . . . , M (L) −1, and M (L) is the number of PDCCH candidates to monitor in a given search space.

15. The communication system of claim 14 , wherein Y k is defined by Y k =(A·Y k-1 )mod D wherein, Y k-1 =n RNTI ≠0, n RNTI is a Radio Network Temporary Identifier (RNTI) number assigned to the UE, A=39827, D=65537, k=└n s /2┘, and n s (nε{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}) is the slot number within a radio frame.

16. The communication system of claim 13 , wherein the UE is configured to:

search 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 until a validly decoded PDCCH candidate is decoded; and

to obtain the selected CC's DCI from the validly decoded PDCCH candidate.

17. The communication system of claim 13 , wherein a PDCCH candidate includes a cyclic redundancy check (CRC) which is masked by a Cell-Radio Network Temporary Identifier (C-RNTI).

18. The communication system of claim 13 , wherein the DCI format includes the CIF.

19. A product including a non-transitory storage medium having stored thereon instructions that, when executed by a machine, result in:

monitoring by an user equipment (UE) operating in a cell and configured with a carrier information field (CIF), a set of PDCCH candidates defined in a search space S k (L) at an aggregation level Lε{1,2,4,8} for a subframe (k) which includes a set of control channel elements (CCEs) and to decode a PDCCH of the set of PDCCH candidates according to downlink control information (DCI).

20. The product of claim 19 , wherein the search space S k (L) is defined by S k (L) =L·{(Y k +m)mod └N CCE,k /L┘}+i wherein N CCE,k is the total number of CCEs in a k th subframe (kε{0,1,2,3,4,5,6,7,8,9}), i=0, . . . , L−1 is a constant, m=0, . . . , M (L) −1, and M (L) is the number of PDCCH candidates to monitor in a given search space.

21. The product of claim 20 , wherein Y k is defined by Y k =(A·Y k-1 )mod D wherein, Y k-1 =n RNTI ≠0, n RNTI is a Radio Network Temporary Identifier (RNTI) number assigned to the UE, A=39827, D=65537, k=└n s /2┘, and n s (nε{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19}) is the slot number within a radio frame.

22. The product of claim 19 , wherein monitoring comprising:

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 until a validly decoded PDCCH candidate is decoded; and

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

23. The product of claim 19 , wherein a PDCCH candidate includes a cyclic redundancy check (CRC) which is masked by a Cell-Radio Network Temporary Identifier (C-RNTI).

24. The product of claim 19 , wherein the DCI format includes the CIF.