Downlink control channel design and signaling for beamformed systems
Transmit and/or receive beamforming may be applied to the control channel transmission/reception, e.g., in mmW access link system design. Techniques to identify candidate control channel beams and/or their location in the subframe structure may provide for efficient WTRU operation. A framework for beam formed control channel design may support varying capabilities of mBs and/or WTRUs, and/or may support time and/or spatial domain multiplexing of control channel beams. For a multi-beam system, modifications to reference signal design may discover, identify, measure, and/or decode a control channel beam. Techniques may mitigate inter-beam interference. WTRU monitoring may consider beam search space, perhaps in addition to time and/or frequency search space. Enhancements to downlink control channel may support scheduling narrow data beams. Scheduling techniques may achieve high resource utilization, e.g., perhaps when large bandwidths are available and/or WTRUs may be spatially distributed.
1. A wireless transmit/receive unit (WTRU) configured for wireless communication, the WTRU comprising: a memory; and
a processor, the processor configured at least to:
receive a Physical Downlink Control Channel (PDCCH) in at least a first beam of one or more beams;
interpret downlink control information (DCI) included in the PDCCH;
determine when spatial information for a downlink (DL) data channel is indicated in the DCI;
determine a receive beam from the spatial information for the DL data channel upon condition that the DCI indicates the spatial information for the DL data channel;
determine that the receive beam is the first beam upon condition that the DCI does not indicate the spatial information for the DL data channel; and
monitor for the DL data channel on the determined receive beam.
2. The WTRU of claim 1 , wherein the spatial information includes at least one of: a grant for the DL data channel; an implicit DL data channel beam identity; or a DL data channel reference signal (RS) sequence number.
3. The WTRU of claim 1 , wherein the indication of the spatial information for the DL data channel is based on a DL reference signal (RS).
4. The WTRU of claim 1 , wherein the processor is further configured to: monitor one or more search spaces, the one or more search spaces configured to provide for at least one of: a monitor of one or more Downlink (DL) control channels, or a receipt of the one or more DL control channels, at least one search space of the one or more search spaces corresponding to at least one reference signal (RS) of one or more reference signals; monitor at least a part of a control region for at least one RS of the one or more reference signals; detect the at least one RS in the at least part of the control region; and monitor the at least one search space corresponding to the at least one RS for at least one DL control channel upon the detection of the at least one RS.
5. The WTRU of claim 4 , wherein the at least one search space includes the DCI, and the processor is further configured to monitor the at least one DL control channel based at least in part on the DCI.
6. The WTRU of claim 4 , wherein the processor is further configured such that the at least part of the control region is one part of a number of parts of the control region.
7. The WTRU of claim 6 , wherein the processor is further configured such that the number of parts of the control region is a function of a number of symbols configured for the control region.
8. The WTRU of claim 4 , further comprising a transceiver, the transceiver being configured to receive the one or more search spaces from a wireless communication system network.
9. The WTRU of claim 4 , wherein the processor is further configured such that the one or more search spaces are predefined.
10. The WTRU of claim 4 , wherein the processor is further configured such that the at least one reference signal of the one or more reference signals is at least one of: a beam reference signal, or an antenna port reference signal.
11. The WTRU of claim 4 , wherein the processor is further configured such that the at least one search space of the one or more search spaces is at least one of: a beam search space, or an antenna port search space.
12. The WTRU of claim 4 , wherein the processor is further configured such that the at least one reference signal in the at least part of the control region is detected upon a strength of the at least one reference signal crossing a predetermined threshold.
13. A method performed by a wireless transmit/receive unit (WTRU) configured for wireless communication, the method comprising:
receiving a Physical Downlink Control Channel (PDCCH) in at least a first beam of one or more beams;
interpreting downlink control information (DCI) included in the PDCCH;
determining when spatial information for a downlink (DL) data channel is indicated in the DCI;
determining a receive beam from the spatial information for the DL data channel upon condition that the DCI indicates the spatial information for the DL data channel;
determining that the receive beam is the first beam upon condition that the DCI does not indicate the spatial information for the DL data channel; and
monitoring for the DL data channel on the determined receive beam.
14. The method of claim 13 , wherein the spatial information includes at least one of: a grant for the DL data channel; an implicit DL data channel beam identity; or a DL data channel reference signal (RS) sequence number.
15. The method of claim 13 , wherein the indication of the spatial information for the DL data channel is based on a DL reference signal (RS).
16. The method of claim 13 , further comprising: monitoring one or more search spaces, the one or more search spaces configured to provide for at least one of: a monitor of one or more Downlink (DL) control channels, or a receipt of the one or more DL control channels, at least one search space of the one or more search spaces corresponding to at least one reference signal (RS) of one or more reference signals; monitoring at least a part of a control region for at least one RS of the one or more reference signals; detecting the at least one RS in the at least part of the control region; and monitoring the at least one search space corresponding to the at least one RS for at least one DL control channel upon the detection of the at least one RS.
17. The method of claim 16 , wherein the at least one search space includes the DCI, and the processor is further configured to monitor the at least one DL control channel based at least in part on the DCI.
18. The method of claim 16 , wherein the processor is further configured such that the at least part of the control region is one part of a number of parts of the control region.
19. The method of claim 18 , wherein the processor is further configured such that the number of parts of the control region is a function of a number of symbols configured for the control region.
20. The method of claim 16 , further comprising receiving the one or more search spaces from a wireless communication system network.