Blind decoding for an enhanced physical downlink control channel (EPDCCH)

1. An apparatus of a user equipment (UE) configured for blind decoding downlink control information (DCI) from an enhanced physical downlink control channel (EPDCCH), the apparatus comprising circuitry configured to:

receive, from a base station, the EPDCCH that includes the DCI; and

attempt one or more times to decode the DCI from enhanced control channel elements (ECCE) of the EPDCCH from physical resource block (PRB) region candidates in a PRB set using a selected set of enhanced resource element group (EREG) index maps for the ECCE until the DCI is successfully decoded, wherein resource elements (REs) of a PRB pair include a block of symbols mapped in sequence to resource elements on an associated port when the REs of the PRB pair are part of the EREGs assigned for the EPDCCH transmission.

2. The apparatus of claim 1 , wherein the circuitry is further configured to decode the DCI with an EREG index map associated with a same aggregation level used to encode the DCI.

3. The apparatus of claim 1 , wherein each EREG index map is configured for a different aggregation level (AL), and the REs of the PRB pair include a block of complex-valued symbols y(0), . . . , y(M symb −1) mapped in sequence starting with y(0) to resource elements (k,l) on the associated antenna port when the REs are part of the EREGS assigned for the EPDCCH transmission, where M symb is a number of modulation symbols to transmit on a physical channel, and the mapping to resource elements (k,l) on antenna port p is an increasing order of first an index k and then an index l, starting with a first slot and ending with a second slot in a subframe.

4. The apparatus of claim 1 , wherein each EREG index map is used to determine which resource elements (RE) in a physical resource block (PRB) pair are associated with the ECCE for aggregation level.

5. The apparatus of claim 1 , wherein the circuitry is further configured to:

fail to decode the DCI when an assumed aggregation level differs from an encoded aggregation level, wherein the processor attempts to decode with an EREG index map associated with the assumed aggregation level, and the encoded aggregation level is the same aggregation level used by an evolved Node B (eNB) to encode the DCI for transmission in the EPDCCH.

6. The apparatus of claim 1 , wherein the circuitry is further configured to:

receive a physical downlink shared channel (PDSCH) with the EPDCCH in a resource allocation (RA), wherein the RA is a RA type 0, RA type 1, or a RA type 2 defined in a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard Release 11; and

rate match the PDSCH around a physical resource block (PRB) pair including the DCI in the EPDCCH.

7. The apparatus of claim 1 , wherein the same aggregation level is used to encode the DCI in 1, 2, 4, 8, 16, or 32 ECCE.

8. The apparatus of claim 1 , wherein the circuitry configured to decode the DCI is further configured to:

resolve an aggregation level ambiguity; and

resolve a lowest ECCE ambiguity.

9. An apparatus of a user equipment (UE) operable to perform blind decoding downlink control information (DCI) from an enhanced physical downlink control channel (EPDCCH), the apparatus comprising circuitry configured to:

receive, at the UE from an evolved Node B (eNB), the EPDCCH along with a physical downlink shared channel (PDSCH) in a resource allocation (RA); and

attempt, at the UE, one or more times to decode the DCI from enhanced control channel elements (ECCE) of the EPDCCH from a physical resource block (PRB) pair using a selected set of enhanced resource element group (EREG) index mappings for the ECCE until the DCI is successfully decoded, wherein each EREG index mapping is configured for a different aggregation level (AL), wherein rate matching is performed on the PDSCH around the PRB pair including the DCI in the EPDCCH.

10. The apparatus of claim 9 , wherein the RA that includes the EPDCCH and the PDSCH is a RA type 0, RA type 1, or a RA type 2 defined in a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard Release 11.

11. The apparatus of claim 9 , wherein the circuitry is further configured to decode the DCI successfully when the EREG index mapping associated with a specified aggregation level is used, wherein the specified aggregation level is used to encode the DCI.

12. The apparatus of claim 9 , wherein each EREG index map is used to determine which resource elements (RE) in a physical resource block (PRB) pair are associated with each ECCE.

13. The apparatus of claim 9 , wherein the REs of the PRB pair include a block of complex-valued symbols y(0), . . . , y(M symb −1) mapped in sequence starting with y(0) to resource elements (k,l) on an associated antenna port when the REs are part of the EREGS assigned for the EPDCCH transmission, where M symb is a number of modulation symbols to transmit on a physical channel, and the mapping to resource elements (k,l) on antenna port p is an increasing order of first an index k and then an index l, starting with a first slot and ending with a second slot in a subframe.

14. The apparatus of claim 9 , wherein each ECCE is distributed with other ECCEs in frequency or time in the PRB pair or multiple PRB pairs or each EREG is distributed with other EREGs in frequency or time in the PRB pair or multiple PRB pairs.

15. The apparatus of claim 9 , wherein the circuitry configured to decode the DCI is further configured to:

determine the aggregation level; and

determine a lowest ECCE value.

16. The apparatus of claim 9 , wherein the circuitry is further configured to:

fail to successfully decode the DCI when an assumed aggregation level differs from an encoded aggregation level, wherein a user equipment (UE) then attempts to decode with a EREG index mapping associated with the assumed aggregation level, and the encoded aggregation level is the aggregation level used by an evolved Node B (eNB) to encode the DCI for transmission in the EPDCCH; and

attempt to decode the DCI using another EREG index mapping associated with another aggregation level.

17. At least one non-transitory machine readable storage medium having instructions embodied thereon for mapping, at a base station, resource elements (RE) to enhanced control channel elements (ECCE) of an enhanced physical downlink control channel (EPDCCH), the instructions when executed perform the following:

determining, using at least one processor of the base station, a number of ECCE used to transmit downlink control information (DCI);

determining, using the at least one processor of the base station, an aggregation level used to transmit the DCI based on the number of ECCE used to transmit the DCI; and

mapping, using the at least one processor of the base station, resource elements (RE) to enhanced resource element groups (EREG) of the ECCE assigned to the DCI using an EREG index.

18. The at least one non-transitory machine readable storage medium of claim 17 , wherein the EREG index is selected based on a localized EPDCCH transmission scheme or a distributed EPDCCH transmission scheme.

19. The at least one non-transitory machine readable storage medium of claim 17 , further comprising instructions which when executed by the at least one processor of the base station performs the following:

mapping the RE to a physical resource block (PRB) pair for the localized EPDCCH transmission scheme using a frequency first sequential mapping across the REs occupied by the DCI; or

mapping the RE to a plurality of PRB pairs for the distributed EPDCCH transmission scheme using a frequency first sequential mapping across the REs occupied by the DCI, wherein one DCI for the distributed EPDCCH transmission scheme is carried using EREGs from the plurality of PRB pairs.

20. The at least one non-transitory machine readable storage medium of claim 17 , further comprising instructions which when executed by the at least one processor of the base station performs the following:

mapping the RE to a physical resource block (PRB) pair for the localized EPDCCH transmission scheme using a time first sequential mapping across the REs occupied by the DCI; or

mapping the RE to a plurality of PRB pairs for the distributed EPDCCH transmission scheme using a time first sequential mapping across the REs occupied by the DCI, wherein one DCI for the distributed EPDCCH transmission scheme is carried using EREGs from the plurality of PRB pairs.

21. The at least one non-transitory machine readable storage medium of claim 17 , wherein the ECCE is transmitted in a physical resource block (PRB) pair and each PRB pair includes four ECCEs or two ECCEs.

22. The at least one non-transitory machine readable storage medium of claim 17 , wherein the REs of the PRB pair include a block of complex-valued symbols y(0), . . . , y(M symb −1) mapped in sequence starting with y(0) to resource elements (k,l) on an associated antenna port when the REs are part of the EREGS assigned for the EPDCCH transmission, where M symb is a number of modulation symbols to transmit on a physical channel, and the mapping to resource elements (k,l) on antenna port p is an increasing order of first an index k and then an index l, starting with a first slot and ending with a second slot in a subframe.

23. The at least one non-transitory machine readable storage medium of claim 17 , further comprising instructions which when executed by the at least one processor of the base station performs the following:

allocating resource to a physical downlink shared channel (PDSCH) with the EPDCCH; and

transmitting the PDSCH in the resource allocation.