Common search space scrambling for MulteFire coverage enhancement
Methods, systems, and devices for wireless communications are described. In some wireless networks (e.g., MulteFire networks), a base station may transmit control information to a user equipment (UE) to enable the UE to access the network and establish a connection with the network. The base station may transmit the control information to the UE in search spaces of an enhanced physical downlink control channel (ePDCCH). In some cases, resources used to transmit control information in a first common search space of the ePDCCH may overlap with resources used to transmit control information in a second common search space of the ePDCCH. In such cases, using the techniques described herein, a base station may encode control information transmitted in the different types of search spaces using different scrambling sequences. As such, a UE may be able to differentiate between the control information transmitted in the different types of common search spaces.
1. A method for wireless communication at a user equipment (UE), comprising:
identifying a first common search space of a first type and a second common search space of a second type to monitor for control information from a base station, wherein resources allocated for the first common search space overlap with resources allocated for the second common search space;
determining a first scrambling sequence used to scramble control information in the first common search space and a second scrambling sequence used to scramble control information in the second common search space; and
decoding the control information in the first common search space based at least in part on the first scrambling sequence or the control information in the second common search space based at least in part on the second scrambling sequence.
2. The method of claim 1 , wherein determining the first scrambling sequence and the second scrambling sequence comprises:
determining the first scrambling sequence and the second scrambling sequence based at least in part on a cell identifier of the base station.
3. The method of claim 1 , wherein the decoding comprises blind decoding.
4. The method of claim 1 , further comprising:
receiving, from the base station, a master information block (MIB) that identifies a resource allocation of the first common search space.
5. The method of claim 4 , further comprising:
identifying a Multefire system information block (SIB) (SIB-MF1) grant in the control information in the first common search space; and
decoding a SIB-MF1 scheduled by the SIB-MF1 grant.
6. The method of claim 5 , further comprising:
determining a resource allocation of the second common search space based at least in part on the decoded SIB-MF1.
7. The method of claim 6 , further comprising:
identifying one or more grants for other SIBs, frame structure information, a random access message, a paging message, a transmit power control (TPC) message, or a combination thereof in the control information in the second common search space.
8. The method of claim 1 , wherein the first common search space of the first type comprises a type- 0 common search space, and the second common search space of the second type comprises a type-1 common search space.
9. The method of claim 1 , wherein the control information in the first common search space and the second common search space is received in an enhanced physical downlink control channel (ePDCCH).
10. The method of claim 1 , wherein the first scrambling sequence is different from the second scrambling sequence.
11. A method for wireless communication at a base station, comprising:
identifying control information to transmit in a first common search space of a first type and control information to transmit in a second common search space of a second type, wherein resources allocated for the first common search space overlap with resources allocated for the second common search space;
encoding the control information to transmit in the first common search space using a first scrambling sequence and the control information to transmit in the second common search space using a second scrambling sequence; and
transmitting the control information encoded using the first scrambling sequence in the first common search space and the control information encoded using the second scrambling sequence in the second common search space.
12. The method of claim 11 , further comprising:
determining the first scrambling sequence and the second scrambling sequence based at least in part on a cell identifier of the base station.
13. The method of claim 11 , further comprising:
transmitting a master information block (MIB) that identifies a resource allocation of the first common search space.
14. The method of claim 13 , further comprising:
transmitting a Multefire system information block (SIB) (SIB-MF1) grant in the control information in the first common search space.
15. The method of claim 14 , further comprising:
transmitting an indication of a resource allocation of the second common search space in a SIB-MF1 scheduled by the SIB-MF1 grant.
16. The method of claim 15 , further comprising:
transmitting one or more grants for other SIBs, frame structure information, a random access message, a paging message, a transmit power control (TPC) message, or a combination thereof in the control information in the second common search space.
17. The method of claim 11 , wherein the first common search space of the first type comprises a type-0 common search space, and the second common search space of the second type comprises a type-1 common search space.
18. The method of claim 11 , wherein the control information in the first common search space and the second common search space is transmitted in an enhanced physical downlink control channel (ePDCCH).
19. The method of claim 11 , wherein the first scrambling sequence is different from the second scrambling sequence.
20. An apparatus for wireless communication at a user equipment (UE), comprising:
a processor;
memory in electronic communication with the processor; and
instructions stored in the memory, wherein the instructions are executable by the processor to:
identify a first common search space of a first type and a second common search space of a second type to monitor for control information from a base station, wherein resources allocated for the first common search space overlap with resources allocated for the second common search space;
determine a first scrambling sequence used to scramble control information in the first common search space and a second scrambling sequence used to scramble control information in the second common search space; and
decode the control information in the first common search space based at least in part on the first scrambling sequence or the control information in the second common search space based at least in part on the second scrambling sequence.
21. The apparatus of claim 20 , wherein the instructions to determine the first scrambling sequence and the second scrambling sequence are executable by the processor to cause the apparatus to:
determine the first scrambling sequence and the second scrambling sequence based at least in part on a cell identifier of the base station.
22. The apparatus of claim 20 , wherein the decoding comprises blind decoding.
23. The apparatus of claim 20 , wherein the instructions are further executable by the processor to cause the apparatus to:
receive, from the base station, a master information block (MIB) that identifies a resource allocation of the first common search space.
24. The apparatus of claim 23 , wherein the instructions are further executable by the processor to cause the apparatus to:
identify a Multefire system information block (SIB) (SIB-MF1) grant in the control information in the first common search space;
decode a SIB-MF1 scheduled by the SIB-MF1 grant; and
determine a resource allocation of the second common search space based at least in part on the decoded SIB-MF1.
25. The apparatus of claim 20 , wherein the first common search space of the first type comprises a type-0 common search space, and the second common search space of the second type comprises a type-1 common search space.
26. The apparatus of claim 20 , wherein the control information in the first common search space and the second common search space is received in an enhanced physical downlink control channel (ePDCCH).
27. The apparatus of claim 20 , wherein the first scrambling sequence is different from the second scrambling sequence.
28. An apparatus for wireless communication at a base station, comprising:
a processor;
memory in electronic communication with the processor; and
instructions stored in the memory, wherein the instructions are executable by the processor to:
identify control information to transmit in a first common search space of a first type and control information to transmit in a second common search space of a second type, wherein resources allocated for the first common search space overlap with resources allocated for the second common search space;
encode the control information to transmit in the first common search space using a first scrambling sequence and the control information to transmit in the second common search space using a second scrambling sequence; and
transmit the control information encoded using the first scrambling sequence in the first common search space and the control information encoded using the second scrambling sequence in the second common search space.
29. The apparatus of claim 28 , wherein the instructions are further executable by the processor to cause the apparatus to:
determine the first scrambling sequence and the second scrambling sequence based at least in part on a cell identifier of the base station.
30. The apparatus of claim 28 , wherein the first scrambling sequence is different from the second scrambling sequence.