Assisted beamforming at mobility
Systems and methods are disclosed herein relating to beam-switching in a wireless system. In some embodiments, a method of operation of a User Equipment device (UE) that transmits and/or receives to and/or from a source Antenna Node (AN) on a source beam comprises performing a Mobility Reference Signal (MRS) search to attempt to detect MRS transmitted by one or more candidate ANs for one or more candidate beam. The method further comprises, if one or more conditions that are indicative of the MRS search being unsuccessful are met, transmitting an indication that the MRS search was unsuccessful. In this manner, one or more network nodes are informed that an action(s) (e.g., assisted beam-formed MRS transmission and/or increasing MRS transmit power at candidate AN(s)) needs to be taken to enable a successful MRS search by the UE.
1. A method of operation of a User Equipment device (UE) that transmits and/or receives to and/or from a source Antenna Node (AN) on a source beam, the method comprising:
performing a Mobility Reference Signal (MRS) search to attempt to detect MRS transmitted by one or more candidate ANs for one or more candidate beams; and
responsive to determining that one or more conditions that are indicative of the MRS search being unsuccessful are met, transmitting an indication that the MRS search was unsuccessful, wherein the one or more conditions comprise a condition that a timer has expired without detection of a MRS having a received Signal to Interference plus Noise Ratio (SINR) that is above a predefined or preconfigured threshold.
2. The method of claim 1 , wherein transmitting the indication comprises transmitting an uplink signal.
3. The method of claim 2 , wherein the uplink signal is an uplink signal configured for the UE to trigger transmission of beam-formed MRS by the one or more candidate ANs.
4. The method of claim 3 , wherein the uplink signal is an Uplink Synchronization Signal (USS).
5. The method of claim 4 , wherein the USS is a random access preamble.
6. The method of claim 3 further comprising receiving configuration of the uplink signal from the source AN of the UE.
7. The method of claim 3 further comprising, after transmitting the uplink signal:
detecting a MRS transmitted by at least one of the one or more candidate ANs; and
reporting the MRS detected by the UE to the source AN.
8. The method of claim 3 further comprising, after transmitting the uplink signal:
detecting a MRS transmitted by at least one of the one or more candidate ANs; and
transmitting an uplink signal that matches the MRS detected by the UE.
9. The method of claim 8 , wherein the uplink signal that matches the MRS detected by the UE is a USS that matches the MRS detected by the UE.
10. The method of claim 1 , wherein transmitting the indication comprises transmitting a report to the source AN, the report comprising one of a group consisting of: an indication that no MRSs were detected by the UE during the MRS search and an indication that any MRSs detected by the UE during the MRS search have a received Signal to Interference plus Noise Ratio (SINR) that is below a predefined or preconfigured threshold.
11. The method of claim 1 , wherein the one or more conditions comprise expiration of a timer.
12. The method of claim 1 , wherein the indication triggers an increase in MRS transmit power by at least one of the one or more candidate ANs.
13. A User Equipment device (UE) that transmits and/or receives to and/or from a source Antenna Node (AN) on a source beam, the UE comprising:
at least one transmitter and at least one receiver;
at least one processor; and
memory storing instructions executable by the at least one processor whereby the UE is operable to:
perform a Mobility Reference Signal (MRS) search to attempt to detect MRS transmitted by one or more candidate ANs for one or more candidate beams; and
if one or more conditions that are indicative of the MRS search being unsuccessful are met, transmit an indication that the MRS search was unsuccessful, wherein the one or more conditions comprise a condition that a timer has expired without detection of a MRS having a received Signal to Interference plus Noise Ratio (SINR) that is above a predefined or preconfigured threshold.
14. A method of operation of a source Antenna Node (AN) that transmits and/or receives to and/or from a User Equipment device (UE) on a source beam, the method comprising:
configuring the UE with an uplink signal to be transmitted by the UE to trigger transmission of beam-formed Mobility Reference Signal (MRS) by one or more candidate ANs;
receiving a report from the UE, the report comprising an indication of a MRS detected by the UE;
determining a candidate AN of the one or more candidate ANs that transmitted the MRS detected by the UE; and
initiating a beam switch for the UE from the source beam to a target beam provided by the candidate AN.
15. The method of claim 14 , wherein the uplink signal is an Uplink Synchronization Signal (USS).
16. The method of claim 15 , wherein the USS is a random access preamble.
17. The method of claim 14 , further comprising negotiating with the one or more candidate ANs to determine the uplink signal to be used by the UE to trigger transmission of beam-formed MRS by the one or more candidate ANs.
18. A source Antenna Node (AN) that transmits and/or receives to and/or from a User Equipment device (UE) on a source beam, the source AN comprising:
at least one processor; and
memory storing instructions executable by the at least one processor whereby the source AN is operable to:
configure the UE with an uplink signal to be transmitted by the UE to trigger transmission of beam-formed Mobility Reference Signal (MRS) by one or more candidate ANs;
receive a report from the UE, the report comprising an indication of a MRS detected by the UE;
determine a candidate AN of the one or more candidate ANs that transmitted the MRS detected by the UE; and
initiate a beam switch for the UE from the source beam to a target beam provided by the candidate AN.