Beam sweeping for SSB polarization switching
Systems and methods for beam selection for communication with a Transmit/Receive Point (TRP) are provided. In some embodiments, a method performed by a wireless device for beam selection for communication with a TRP includes: determining how the TRP changes a polarization state for a series of Synchronization Signal Block (SSB) bursts; sweeping through candidate Receive (RX) beams during SSB reception using an order based on how the TRP changes the polarization state; and combining channel measurements from sweeping through the candidate RX beams to determine a target RX beam of the candidate RX beams. In this way, wireless device beam selection can be improved which will improve Downlink (DL) performance. In case the wireless device has beam correspondence, the wireless device RX beam is also likely to be used as the Uplink (UL) Transmit (TX) beam, and in that case UL performance will also be improved.
1. A method performed by a wireless device for beam selection for communication with a Transmit/Receive Point (TRP), the method comprising:
determining how the TRP changes a polarization state for a series of Synchronization Signal Block (SSB) bursts;
sweeping through candidate Receive (RX) beams during SSB reception using an order based on how the TRP changes the polarization state, wherein sweeping through the candidate RX beams comprises:
sweeping through each candidate RX beam of the candidate RX beams during SSB reception for a first polarization state;
sweeping through each candidate RX beam of the candidate RX beams during SSB reception for a second polarization state;
sweeping through a first set of the candidate RX beams during a first SSB burst for the first polarization state; and
sweeping through a second set of the candidate RX beams during a second SSB burst for the first polarization state; and
combining channel measurements from sweeping through the candidate RX beams to determine a target RX beam of the candidate RX beams, wherein combining the channel measurements comprises:
averaging the channel measurements from each of the first polarization state and the second polarization state; and
selecting the target RX beam having a highest averaged channel measurement.
2. The method of claim 1 , wherein determining how the TRP changes the polarization state for the series of SSB bursts is based on statistics of channel measurements from past SSB bursts.
3. The method of claim 2 , wherein combining the channel measurements is based on the statistics of channel measurements from the past SSB bursts.
4. The method of claim 1 , wherein determining how the TRP changes the polarization state for the series of SSB bursts comprises receiving signaling from the TRP.
5. The method of claim 4 , wherein combining the channel measurements is based on the signaling from the TRP.
6. The method of claim 1 , wherein determining how the TRP changes the polarization state for the series of SSB bursts is based on assuming the TRP changes the polarization state for each consecutive SSB burst.
7. The method of claim 1 , further comprising:
selecting the target RX beam when receiving one or more of a data transmission and a control transmission from the TRP.
8. The method of claim 1 , wherein combining the channel measurements comprises:
summing the channel measurements from each of the first polarization state and the second polarization state; and
selecting the target RX beam having a highest summed channel measurement.
9. The method of claim 1 , wherein the TRP changes between the first polarization state and the second polarization state orthogonal to the first polarization state.
10. The method of claim 1 , wherein the method is performed when the wireless device is in a connected state and the wireless device has data to receive or transmit.
11. The method of claim 1 , wherein the method is performed when the wireless device is in the connected state and the wireless device has no data to receive or transmit.
12. The method of claim 1 , wherein the method is performed when the wireless device is in an idle state.
13. The method of claim 12 , wherein the target RX beam is determined before the wireless device is in a radio resource control (RRC) connected state.
14. A method performed by a Transmit/Receive Point (TRP) for beam selection for communication with a wireless device, the method comprising:
determining how the TRP changes a polarization state for a series of Synchronization Signal Block (SSB) bursts; and
transmitting the series of SSB bursts with the determined polarization state, wherein the wireless device sweeps through candidate Receive (RX) beams during reception of the SSB using an order based on how the TRP changes the polarization state, wherein sweeping through the candidate RX beams comprises:
sweeping through each candidate RX beam of the candidate RX beams during SSB reception for a first polarization state;
sweeping through each candidate RX beam of the candidate RX beams during SSB reception for a second polarization state;
sweeping through a first set of the candidate RX beams during a first SSB burst for the first polarization state; and
sweeping through a second set of the candidate RX beams during a second SSB burst for the first polarization state,
wherein the wireless device combines channel measurements from sweeping through the candidate RX beams to determine a target RX beam of the candidate RX beams, and wherein combining the channel measurements comprises:
averaging the channel measurements from each of the first polarization state and the second polarization state; and
selecting the target RX beam having a highest averaged channel measurement.
15. The method of claim 14 , further comprising:
signaling how the TRP changes the polarization state for the series of SSB bursts.
16. A wireless device for enabling transmission feedback, the wireless device comprising:
one or more processors; and
memory storing instructions executable by the one or more processors, whereby the wireless device is operable to:
determine how a Transmit/Receive Point (TRP) changes a polarization state for a series of Synchronization Signal Block (SSB) bursts;
sweep through candidate Receive (RX) beams during SSB reception using an order based on how the TRP changes the polarization state, wherein sweep through the candidate RX beams comprises:
sweep through each candidate RX beam of the candidate RX beams during SSB reception for a first polarization state;
sweep through each candidate RX beam of the candidate RX beams during SSB reception for a second polarization state;
sweep through a first set of the candidate RX beams during a first SSB burst for the first polarization state; and
sweep through a second set of the candidate RX beams during a second SSB burst for the first polarization state; and
combine channel measurements from sweeping through the candidate RX beams to determine a target RX beam of the candidate RX beams, wherein combine the channel measurements comprises:
average the channel measurements from each of the first polarization state and the second polarization state; and
select the target RX beam having a highest averaged channel measurement.