Polarization diversity in time-domain beamforming
A network node, computer program product, and a method by a network node to allocate at least two beams in a slot to schedule multiple user equipments, UEs, are provided. Each UE is allocated to a baseband port of a plurality of baseband ports such that there is more than one UE allocated to each baseband port. For each baseband port of the plurality of baseband ports: the baseband port is mapped to a polarization of an antenna having multiple polarizations and to one beam of a plurality of beams. The polarization of a baseband port is switched in a time domain to create time diversity of services towards the multiple UEs, wherein a UE is subject to a first polarization for a subset of time occasions and to a second polarization for other time occasions.
1. A method by a network node to allocate two beams in a slot to schedule multiple user equipments, UEs, the method comprising:
allocating each UE to a baseband port of a plurality of baseband ports such that there is more than one UE allocated to each baseband port of the plurality of baseband ports; and
for each baseband port of the plurality of baseband ports:
mapping the baseband port to a polarization of an antenna having multiple polarizations and to one beam of a plurality of beams, wherein a number of the plurality of beams matches a number of the multiple polarizations; and
switching the polarization of a baseband port in a time domain to create time diversity of services towards the multiple UEs, wherein a UE is subject to a first polarization for a subset of time occasions and to a second polarization for other time occasions.
2. The method of claim 1 , wherein allocating each UE to a baseband port of the plurality of baseband ports comprises allocating each UE to a baseband port in which the UE is located in a coverage area of a respective beam to which the baseband port is mapped.
3. The method of claim 1 , further comprising:
responsive to there being a switch in polarization within a slot, providing a demodulation reference signal, DM-RS, for the UE to estimate the channel in regard to upcoming symbols by performing channel estimation without any filtering.
4. The method of claim 3 , further comprising:
providing an indication to the UE to enable or disable DM-RS filtering when performing measurements on the DM-RS.
5. The method of claim 4 , wherein providing the indication comprises setting a parameter in a control resource set information element, IE, to indicate whether the DM-RS can be subject to filtering by the UE.
6. The method of claim 5 , wherein setting the parameter in the control resource set IE comprises setting a dmrs-NoFilteringWithinSlot parameter.
7. The method of claim 4 , wherein providing the indication comprises one of:
setting a parameter in a DM-RS-downlink configuration information element, IE, to indicate whether the DM-RS can be subject to filtering by the UE;
providing a DM-RS No Filtering Within Slot Activation/Deactivation medium access control, MAC, control element, CE to indicate whether to activate or deactivate no filtering for DM-RS within a slot; and
providing a downlink control information, DCI, that indicates whether DM-RS no filtering is enabled.
8. The method of claim 4 , further comprising dynamically scheduling a physical downlink shared channel for which DM-RS filtering is enabled or disabled by the UE based on the indication.
9. The method of claim 1 , wherein switching the polarization of the baseband port comprises one of:
switching the polarization for hybrid automatic repeat request transmission, HARQ transmission, responsive to a failure of decoding of an initial HARQ transmission or a retransmitted HARQ transmission; and
switching a polarization of a baseband port associated with a downlink channel based on uplink sounding reference signal, SRS, detection results showing which polarization has a better channel quality for downlink.
10. The method of claim 1 , further comprising performing filtering on an uplink channel responsive to determining to provide time diversity on the uplink channel.
11. A network node comprising:
processing circuitry; and
memory coupled with the processing circuitry, wherein the memory includes instructions that when executed by the processing circuitry causes the network node to perform operations comprising:
allocating each user equipment, UE, to a baseband port of a plurality of baseband ports such that there is more than one UE allocated to each of the plurality of baseband ports; and
for each baseband port of the plurality of baseband ports:
mapping the baseband port to a polarization of an antenna having multiple polarizations and to one beam of a plurality of beams, wherein a number of the plurality of beams matches a number of the multiple polarizations; and
switching the polarization of a baseband port in a time domain to create time diversity of services towards the multiple UEs, wherein a UE is subject to a first polarization for a subset of time occasions and to a second polarization for other time occasions.
12. The network node of claim 11 , wherein the memory includes further instructions that when executed by the processing circuitry causes the network node to perform operations of allocating each UE to a baseband port of the plurality of baseband ports comprises allocating each UE to a baseband port in which the UE is located in a coverage area of a respective beam to which the baseband port is mapped.
13. A computer program product comprising a non-transitory storage medium including program code to be executed by processing circuitry of a network node, whereby execution of the program code causes the network node to perform operations comprising:
allocating each user equipment, UE, to a baseband port of a plurality of baseband ports such that there is more than one UE allocated to each of the plurality of baseband ports; and
for each baseband port of the plurality of baseband ports:
mapping the baseband port to a polarization of an antenna having multiple polarizations and to one beam of a plurality of beams, wherein a number of the plurality of beams matches a number of the multiple polarizations; and
switching the polarization of a baseband port in a time domain to create time diversity of services towards the multiple UEs, wherein a UE is subject to a first polarization for a subset of time occasions and to a second polarization for other time occasions.
14. The computer program product of claim 13 , wherein the non-transitory storage medium includes further program code to be executed by the processing circuitry of the network node, whereby execution of the further program code causes the network node to perform operations of allocating each UE to a baseband port of the plurality of baseband ports comprises allocating each UE to a baseband port in which the UE is located in a coverage area of a respective beam to which the baseband port is mapped.