Techniques for improved control channels
Methods, systems, and devices for wireless communication are described. A method may include receiving a control transmission from a base station, identifying a control channel search space organized according to a nested structure, the control channel search space including a plurality of control channel candidates associated with one or more control channel elements (CCEs) and an aggregation level, and searching the received control transmission to identify a control channel for the UE using the plurality of control channel candidates. Another method may include determining whether to reorder resource element group (REG) indices for a received control channel transmission based, at least in part, on a transmission mode associated with the control channel transmission. Another method may include decoding a received control channel transmission, where the downlink control information (DCI) formats may be constrained to an integer multiple of a predetermined base number of bits N.
1. A method for wireless communication at a user equipment (UE), comprising:
receiving, from a base station, a control-resource set that includes a plurality of resource element groups (REGs) organized into one or more control channel elements based at least in part on a configuration of the control-resource set;
identifying a REG index for each REG of the plurality of REGs;
determining a transmission mode type of the control-resource set based at least in part on whether the configuration of the control-resource set is associated with broadcast transmission, wherein the transmission mode type is determined from a set of transmission mode types comprising broadcast transmission and unicast transmission;
reordering, before decoding the control-resource set and based at least in part on determining the transmission mode type of the control-resource set, the identified REG indices according to a bit-reversal de-interleaving procedure corresponding to the transmission mode type of the configuration of the control-resource set after determining the transmission mode type of the control-resource set, wherein the bit-reversal de-interleaving procedure comprises switching each bit of an REG binary index from a first value to a second value or from the second value to the first value; and
decoding the control-resource set based at least in part on reordering the identified REG indices according to the transmission mode type.
2. The method of claim 1 , wherein the reordering comprises:
reordering the identified REG indices for each of the plurality of REGs based at least in part on a bit-reversal de-interleaving procedure corresponding to the broadcast transmission mode type.
3. The method of claim 1 , wherein the reordering comprises:
reordering the identified REG indices for each of the plurality of REGs.
4. The method of claim 3 , further comprising:
performing wide-band channel estimation independent of the reordering.
5. The method of claim 1 , further comprising:
refraining from reordering the identified REG indices for each of the plurality of REGs after determining the transmission mode type of the control-resource set.
6. The method of claim 5 , further comprising:
refraining from performing wide-band channel estimation.
7. The method of claim 1 , further comprising:
generating a control channel based at least in part on decoding the control-resource set.
8. The method of claim 1 , further comprising:
determining that the control-resource set will be transmitted via broadcast, wherein reordering the identified REG indices comprises:
reordering the identified REG indices after determining that the transmission mode type of the control-resource set is broadcast transmission.
9. An apparatus for wireless communication, comprising:
a processor,
memory in electronic communication with the processor; and
instructions stored in the memory and executable by the processor to cause the apparatus to:
receive, from a base station, a control-resource set that includes a plurality of resource element groups (REGs) organized into one or more control channel elements based at least in part on a configuration of the control-resource set;
identify a REG index for each REG of the plurality of REGs;
determine a transmission mode type of the control-resource set based at least in part on whether the configuration of the control-resource set is associated with broadcast transmission, wherein the transmission mode type is determined from a set of transmission mode types comprising broadcast transmission and unicast transmission;
reorder, before decoding the control-resource set and based at least in part on determining the transmission mode type of the control-resource set, the identified REG indices according to a bit-reversal de-interleaving procedure corresponding to the transmission mode type of the configuration of the control-resource set after determining the transmission mode type of the control-resource set, wherein the bit-reversal de-interleaving procedure comprises switching each bit of an REG binary index from a first value to a second value or from the second value to the first value; and
decode the control-resource set based at least in part on reordering the identified REG indices according to the transmission mode type.
10. The apparatus of claim 9 , wherein the instructions to reorder the identified REG indices further include instructions that are executable by the processor to cause the apparatus to:
reorder the identified REG indices for each of the plurality of REGs based at least in part on a bit-reversal de-interleaving procedure corresponding to a broadcast transmission mode type.
11. The apparatus of claim 9 , wherein the instructions to reorder the identified REG indices further include instructions that are executable by the processor to cause the apparatus to:
reorder the identified REG indices for each of the plurality of REGs.
12. The apparatus of claim 11 , wherein the instructions are further executable by the processor to cause the apparatus to:
perform wide-band channel estimation independent of the reordering.
13. The apparatus of claim 9 , wherein the instructions are further executable by the processor to cause the apparatus to:
refrain from reordering the identified REG indices for each of the plurality of REGs after determining the transmission mode type of the control-resource set.
14. The apparatus of claim 13 , wherein the instructions are further executable by the processor to cause the apparatus to:
refrain from performing wide-band channel estimation.
15. The apparatus of claim 9 , wherein the instructions are further executable by the processor to cause the apparatus to:
generate a control channel based at least in part on decoding the control-resource set.
16. The apparatus of claim 9 , wherein the instructions are further executable by the processor to cause the apparatus to:
determine that the control-resource set will be transmitted via broadcast, wherein reordering the identified REG indices comprises:
reorder the identified REG indices after determining that the transmission mode type of the control-resource set is broadcast transmission.
17. An apparatus for wireless communication, comprising:
means for receiving, from a base station, a control-resource set that includes a plurality of resource element groups (REGs) organized into one or more control channel elements based at least in part on a configuration of the control-resource set;
means for identifying a REG index for each REG of the plurality of REGs;
means for determining a transmission mode type of the control-resource set based at least in part on whether the configuration of the control-resource set is associated with broadcast transmission, wherein the transmission mode type is determined from a set of transmission mode types comprising broadcast transmission and unicast transmission;
means for reordering, before decoding the control-resource set and based at least in part on determining the transmission mode type of the control-resource set, the identified REG indices according to a bit-reversal de-interleaving procedure corresponding to the transmission mode type of the configuration of the control-resource set after determining the transmission mode type of the control-resource set, wherein the bit-reversal de-interleaving procedure comprises switching each bit of an REG binary index from a first value to a second value or from the second value to the first value; and
means for decoding the control-resource set based at least in part on reordering the identified REG indices according to the transmission mode type.
18. The apparatus of claim 17 , wherein the means for reordering the identified REG indices comprise:
means for reordering the identified REG indices for each of the plurality of REGs based at least in part on a bit-reversal de-interleaving procedure corresponding to a broadcast transmission mode type.
19. The apparatus of claim 17 , wherein the means for reordering the identified REG indices comprise:
means for reordering the identified REG indices for each of the plurality of REGs.
20. The apparatus of claim 19 , further comprising:
means for performing wide-band channel estimation independent of the reordering.
21. The apparatus of claim 17 , further comprising:
means for refraining from reordering the identified REG indices for each of the plurality of REGs after determining the transmission mode type of the control-resource set.
22. The apparatus of claim 21 , further comprising:
means for refraining from performing wide-band channel estimation.
23. The apparatus of claim 17 , further comprising:
means for generating a control channel based at least in part on decoding the control-resource set.
24. The apparatus of claim 17 , further comprising:
means for determining that the control-resource set will be transmitted via broadcast, wherein reordering the identified REG indices comprises:
means for reordering the identified REG indices after determining that the transmission mode type of the control-resource set is broadcast transmission.
25. A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to:
receive, from a base station, a control-resource set that includes a plurality of resource element groups (REGs) organized into one or more control channel elements based at least in part on a configuration of the control-resource set;
identify a REG index for each REG of the plurality of REGs;
determine a transmission mode type of the control-resource set based at least in part on whether the configuration of the control-resource set is associated with broadcast transmission, wherein the transmission mode type is determined from a set of transmission mode types comprising broadcast transmission and unicast transmission;
reorder, before decoding the control-resource set and based at least in part on determining the transmission mode type of the control-resource set, the identified REG indices according to a bit-reversal de-interleaving procedure corresponding to the transmission mode type of the configuration of the control-resource set after determining whether the transmission mode type of the control-resource set, wherein the bit-reversal de-interleaving procedure comprises switching each bit of an REG binary index from a first value to a second value or from the second value to the first value; and
decode the control-resource set based at least in part on reordering the identified REG indices according to the transmission mode type.
26. The non-transitory computer-readable medium of claim 25 , wherein the instructions to reorder the identified REG indices further include instructions that are executable to:
reorder the identified REG indices for each of the plurality of REGs based at least in part on a bit-reversal de-interleaving procedure corresponding to a broadcast transmission mode type.
27. The non-transitory computer-readable medium of claim 25 , wherein the instructions to reorder the identified REG indices further include instructions that are executable to:
reorder the identified REG indices for each of the plurality of REGs.
28. The non-transitory computer-readable medium of claim 27 , wherein the instructions are further executable to:
perform wide-band channel estimation independent of the reordering.
29. The non-transitory computer-readable medium of claim 25 , wherein the instructions are further executable to:
refrain from reordering the identified REG indices for each of the plurality of REGs after determining the transmission mode type of the control-resource set.
30. The non-transitory computer-readable medium of claim 29 , wherein the instructions are further executable to:
refrain from performing wide-band channel estimation.