Control channel management for relay backhaul
Aspects of the present disclosure provide techniques for managing control channels for relays that utilize half-duplex operation. According to certain aspects, a certain type of PDCCH may be selected based on one or more criteria.
1. A method for wireless communications by a base station, comprising:
selecting, based on one or more criteria, between at least a first type of physical downlink control channel (PDCCH) and a second type of PDCCH for transmission to a half duplex relay node used to relay transmissions between the base station and a user equipment (UE) served by the base station; and
transmitting a PDCCH of the selected type to the half duplex relay node in a subframe.
2. The method of claim 1 , wherein:
the first type of PDCCH is based on a TDM structure; and
the second type of PDCCH is based on an FDM structure.
3. The method of claim 1 , wherein:
the first type of PDCCH is a relay PDCCH (R-PDCCH); and
the second type of PDCCH is an enhanced PDCCH (ePDCCH).
4. The method of claim 3 , further comprising configuring a plurality of resource allocations for R-PDCCH.
5. The method of claim 3 , further comprising configuring an end symbol in a subframe for ePDCCH.
6. The method of claim 1 , wherein:
the first type of PDCCH is transmitted with common reference signals (CRS) or demodulation reference signals (DM-RS); and
the second type of PDCCH is transmitted with DM-RS and not CRS.
7. The method of claim 1 , wherein the one or more criteria relate to processing capabilities of the relay node.
8. The method of claim 1 , wherein the one or more criteria relate to channel conditions between the relay node and the base station.
9. The method of claim 8 , wherein:
the first type of PDCCH is selected if an uplink timing advance of the relay node is above a threshold value; and
the second type of PDCCH is selected if the uplink timing advance of the relay node is below a threshold value.
10. The method of claim 1 , wherein:
the one or more criteria relate to a type of PDCCH the relay node used for initial access when acting as a user equipment.
11. The method of claim 1 , wherein:
the one or more criteria relate to a preferred type of PDCCH as indicated by the relay node.
12. The method of claim 1 , further comprising:
providing an indication of the selected type of PDCCH to the relay node.
13. A method for wireless communications by a relay node, comprising:
determining between at least monitoring for a first type of physical downlink control channel (PDCCH) and monitoring for a second type of PDCCH transmitted from a base station that uses the relay node to relay transmissions between the base station and a user equipment (UE) served by the base station; and
monitoring for a PDCCH of the determined type in a subframe.
14. The method of claim 13 , wherein:
the first type of PDCCH is based on a TDM structure; and
the second type of PDCCH is based on an FDM structure.
15. The method of claim 13 , wherein:
the first type of PDCCH is a relay PDCCH (R-PDCCH); and
the second type of PDCCH is an enhanced PDCCH (ePDCCH).
16. The method of claim 15 , further comprising receiving an indication of configuration of a plurality of resource allocations for R-PDCCH.
17. The method of claim 15 , further comprising receiving an indication of configuration of an end symbol in a subframe for ePDCCH.
18. The method of claim 13 , wherein:
the first type of PDCCH is transmitted with common reference signals (CRS) or demodulation reference signals (DM-RS); and
the second type of PDCCH is transmitted with DM-RS and not CRS.
19. The method of claim 13 , wherein the determining is based, at least in part, on channel conditions between the relay node and the base station.
20. The method of claim 19 , wherein the determining comprises:
determining to monitor for the first type of PDCCH if an uplink timing advance of the relay node is above a threshold value; and
determining to monitor for the second type of PDCCH if the uplink timing advance of the relay node is below a threshold value.
21. The method of claim 13 , wherein the determining is based, at least in part, on a type of PDCCH the relay node used for initial access when acting as a user equipment.
22. The method of claim 13 , further comprising:
transmitting an explicit indication of a preferred type of PDCCH from the relay node.
23. The method of claim 13 , wherein the determining comprises:
receiving an indication of a selected type of PDCCH from the base station.
24. An apparatus for wireless communications by a base station, comprising:
at least one processor configured to select, based on one or more criteria, between at least a first type of physical downlink control channel (PDCCH) and a second type of PDCCH for transmission to a half duplex relay node used to relay transmissions between the base station and a user equipment (UE) served by the base station and transmit a PDCCH of the selected type to the half duplex relay node in a subframe; and
a memory coupled with the at least one processor.
25. The apparatus of claim 24 , wherein:
the one or more criteria relate to a type of PDCCH the relay node used for initial access when acting as a user equipment.
26. The apparatus of claim 24 , wherein the at least one processor is further configured to provide an indication of the selected type of PDCCH to the relay node.
27. An apparatus for wireless communications by a relay node, comprising:
at least one processor configured to determine between at least monitoring for a first type of physical downlink control channel (PDCCH) and monitoring for a second type of PDCCH transmitted from a base station that uses the relay node to relay transmissions between the base station and a user equipment (UE) served by the base station, and monitor for a PDCCH of the determined type in a subframe; and
a memory coupled with the at least one processor.
28. The apparatus of claim 27 , wherein the determining is based, at least in part, on a type of PDCCH the relay node used for initial access when acting as a user equipment.
29. The apparatus of claim 27 , wherein the at least one processor is further configured to transmit an explicit indication of a preferred type of PDCCH from the relay node.
30. The apparatus of claim 27 , wherein the determining comprises:
receiving an indication of a selected type of PDCCH from the base station.