Systems and methods for an enhanced control channel
Methods and systems for sending and receiving an enhanced downlink control channel are disclosed. The method may include receiving control channel information via an enhanced control channel. The method may also include using the control channel information to receive a shared channel. The method may include detecting the presence of the enhanced control channel in a given subframe. The enhanced control channel may be transmitted over multiple antenna ports. For example, code divisional multiplexing and de-multiplexing and the use of common and UE-specific reference signals may be utilized. New control channel elements may be defined, and enhanced control channel state information (CSI) feedback may be utilized. The presence or absence of legacy control channels may affect the demodulation and or decoding methods. The method may be implemented at a WTRU.
1. A method implemented by a wireless transmit/receive unit (WTRU), the method comprising:
receiving a radio resource control (RRC) message comprising physical downlink control channel configuration information, the physical downlink control channel configuration information indicating a set of time slots for attempting to decode a physical downlink control channel transmission, and the physical downlink control channel configuration information indicating one or more resource blocks for attempting to decode the physical downlink control channel transmission;
determining a first set of one or more precoded demodulation reference signals (DM-RSs) and a second set of one or more precoded DM-RSs used for attempting to decode the physical downlink control channel transmission, wherein the first set of one or more precoded DM-RSs are used for channel estimation for a first subset of resource elements used to attempt to decode the physical downlink control channel transmission and the second set of one or more precoded DM-RSs are used for channel estimation for a second subset of the resource elements used to attempt to decode the physical downlink control channel transmission;
receiving the physical downlink control channel transmission during at least one time slot of the set of time slots indicated by the physical downlink control channel configuration information and in the one or more resource blocks indicated by the physical downlink control channel configuration information, wherein receiving the physical downlink control channel transmission comprises:
demodulating the physical downlink control channel transmission based on at least one of the first or second set of the one more precoded DM-RSs, and
decoding downlink control information (DCI) for a downlink transmission based on the physical downlink control transmission; and
receiving the downlink transmission in accordance with the DCI comprised in the physical downlink control channel transmission.
2. The method of claim 1 , wherein the first set of one or more precoded DM-RSs are determined to be used for channel estimation for the first subset of resource elements used for attempting to decode the physical downlink control channel transmission based on a location of the first subset of resource elements.
3. The method of claim 1 , wherein the physical downlink control channel configuration information indicates that the first set of one or more precoded DM-RSs are to be used for channel estimation for the first subset of resource elements.
4. The method of claim 1 , wherein the first set of one or more precoded DM-RSs and the first subset of resource elements are associated with a first beamforming processing and the second set of one or more precoded DM-RSs and the second subset of resource elements are associated with a second beamforming processing.
5. The method of claim 1 , wherein the first set of one or more precoded DM-RSs and the first subset of resource elements are associated with a first antenna port and the second set of one or more precoded DM-RSs and the second subset of resource elements are associated with a second antenna port.
6. The method of claim 1 , wherein the physical downlink control channel configuration information further indicates one or more orthogonal frequency division multiplexing (OFDM) symbols to use for attempting to decode the physical downlink control channel transmission in the set of one or more time slots.
7. The method of claim 1 , wherein the first subset of resource elements corresponds to a first plurality of resource element groups (REGs) and the second subset of resource elements corresponds to a second plurality of REGs.
8. A wireless transmit/receive unit (WTRU) comprising a processor and memory, the processor and memory configured to:
receive a radio resource control (RRC) message comprising physical downlink control channel configuration information, the physical downlink control channel configuration information indicating a set of time slots for attempting to decode a physical downlink control channel transmission, and the physical downlink control channel configuration information indicating one or more resource blocks for attempting to decode the physical downlink control channel transmission;
determine a first set of one or more precoded demodulation reference signals (DM-RSs) and a second set of one or more precoded DM-RSs used for attempting to decode the physical downlink control channel transmission, wherein the first set of one or more precoded DM-RSs are used for channel estimation for a first subset of resource elements used to attempt to decode the physical downlink control channel transmission and the second set of one or more precoded DM-RSs are used for channel estimation for a second subset of the resource elements used to attempt to decode the physical downlink control channel transmission;
receive the physical downlink control channel transmission during at least one time slot of the set of time slots indicated by the physical downlink control channel configuration information and in the one or more resource blocks indicated by the physical downlink control channel configuration information, wherein the processor and memory being configured to receive the physical downlink control channel transmission comprises the processor and memory being configured to:
demodulate the physical downlink control channel transmission based on at least one of the first or second set of the one more precoded DM-RSs, and
decode downlink control information (DCI) for a downlink transmission based on the physical downlink control transmission; and
receive the downlink transmission in accordance with the DCI comprised in the physical downlink control channel transmission.
9. The WTRU of claim 8 , wherein the WTRU is configured to use the first set of one or more precoded DM-RSs for channel estimation for the first subset of resource elements based on a location of the first subset of resource elements.
10. The WTRU of claim 8 , wherein the physical downlink control channel configuration information indicates that the first set of one or more precoded DM-RSs are to be used for channel estimation for the first subset of resource elements.
11. The WTRU of claim 8 , wherein the first set of one or more precoded DM-RSs and the first subset of resource elements are associated with a first beamforming processing and the second set of one or more precoded DM-RSs and the second subset of resource elements are associated with a second beamforming processing.
12. The WTRU of claim 8 , wherein the first set of one or more precoded DM-RSs and the first subset of resource elements are associated with a first antenna port and the second set of one or more precoded DM-RSs and the second subset of resource elements are associated with a second antenna port.
13. The WTRU of claim 8 , wherein the physical downlink control channel configuration information further indicates one or more orthogonal frequency division multiplexing (OFDM) symbols to use for attempting to decode the physical downlink control channel transmission in the set of one or more time slots.
14. The WTRU of claim 8 , wherein the first subset of resource elements corresponds to a first plurality of resource element groups (REGs) and the second subset of resource elements corresponds to a second plurality of REGs.
15. A base station comprising a processor and memory, the processor and memory configured to:
send a radio resource control (RRC) message to a wireless transmit/receive unit (WTRU), the RRC message comprising physical downlink control channel configuration information, the physical downlink control channel configuration information indicating a set of time slots for the WTRU to attempt to decode a physical downlink control channel transmission, and the physical downlink control channel configuration information indicating one or more resource blocks for the WTRU to use to attempt to decode the physical downlink control channel transmission;
transmit a first set of one or more precoded demodulation reference signals (DM-RSs) and a second set of one or more precoded DM-RSs, wherein the first and second sets of one or more precoded DM-RSs are transmitted during at least one time slot of the set of time slots indicated by the physical downlink control channel configuration information and in at least one of the one or more resource blocks indicated by the physical downlink control channel configuration information, wherein the first set of one or more precoded DM-RSs are associated with a first subset of resource elements that the base station has configured the WTRU to use to attempt to decode the physical downlink control channel transmission and the first second set of one or more precoded DM-RSs are associated with a second subset of resource elements that the base station has configured the WTRU use to attempt to decode the physical downlink control channel transmission;
transmit the physical downlink control channel transmission, the physical downlink control transmission comprising downlink control information (DCI) for a downlink transmission; and
transmit the downlink transmission in accordance with the DCI comprised in the physical downlink control channel transmission.
16. The base station of claim 15 , wherein the physical downlink control channel configuration information indicates that the first set of one or more precoded DM-RSs are to be used for channel estimation by the WTRU for the first subset of resource elements.
17. The base station of claim 15 , wherein the first set of one or more precoded DM-RSs and the first subset of resource elements are associated with a first beamforming processing and the second set of one or more precoded DM-RSs and the second subset of resource elements are associated with a second beamforming processing.
18. The base station of claim 15 , wherein the first set of one or more precoded DM-RSs and the first subset of resource elements are associated with a first antenna port and the second set of one or more precoded DM-RSs and the second subset of resource elements are associated with a second antenna port.
19. The base station of claim 15 , wherein the first subset of resource elements corresponds to a first control channel element, and the second subset of resource elements corresponds to a second control channel element.
20. The base station of claim 15 , wherein the first subset of resource elements corresponds to a first plurality of resource element groups (REGs) and the second subset of resource elements corresponds to a second plurality of REGs.