Mechanisms to operate downlink wideband carrier in unlicensed band

Abstract

Systems and methods for downlink transmission using a wideband unlicensed band carrier in 5G networks are described. The gNB determines, based on LBT, which LBT subchannel(s) in a BWP are available during a COT. The gNB transmits an indication of the available subchannels in DCI format 2_0 of a GC-PDCCH of one of the available subchannels and subsequently transmits a PDSCH using the available subchannel(s). The gNB may configure multiple opportunities during the COT and transmit the GC-PDCCH after the initial opportunity. The PDSCH is transmitted on all available subchannels during the COT and, during an initial portion of the COT, may transmit the PDSCH by puncturing symbols of the unavailable subchannels. The indication may include a bitmap of available subchannels or if the LBT outcome is not available, may indicate all or none of the subchannels or available or that the outcome is not available.

What is claimed is: 
     
         1 . An apparatus for a 5 th  generation NodeB (gNB), the apparatus comprising processing circuitry and memory:
 wherein the processing circuitry is configured to:
 determine, based on performance of a listen-before-talk (LBT) procedure, which one or more LBT bandwidths in a bandwidth part (BWP) in an unlicensed channel are available for transmission by the gNB; 
 encode, for transmission to a user equipment (UE) on an available LBT bandwidth of the one or more LBT bandwidths, an indication of the one or more LBT bandwidths that are available in the unlicensed channel; and 
 encode, for transmission to the UE, a physical downlink shared channel (PDSCH) using at least one available LBT bandwidth of the one or more LBT bandwidths; and 
   the memory is configured to store the indication.   
     
     
         2 . The apparatus of  claim 1 , wherein the processing circuitry is configured to encode, for transmission to the UE, the indication in a group common physical downlink control channel (GC-PDCCH) in a control resource set (CORESET) on the available LBT bandwidth. 
     
     
         3 . The apparatus of  claim 2 , wherein the processing circuitry is configured to determine at least one PDCCH candidate for the GC-PDCCH in each LBT bandwidth prior to transmission of the GC-PDCCH. 
     
     
         4 . The apparatus of  claim 3 , wherein a number of PDCCH candidates is at least a number of LBT bandwidths. 
     
     
         5 . The apparatus of  claim 2 , wherein the processing circuitry is configured to encode the indication in downlink control information (DCI) format 2_0 of the GC-PDCCH. 
     
     
         6 . The apparatus of  claim 2 , wherein the CORESET is split among each LBT bandwidth in the BWP. 
     
     
         7 . The apparatus of  claim 2 , wherein:
 a span of the CORESET is less than a span of a single LBT bandwidth, and   each LBT bandwidth contains a monitoring location for the UE.   
     
     
         8 . The apparatus of  claim 7 , wherein the processing circuitry is further configured encode, for transmission to the UE, a monitoring subband information element (IE) in a Radio Resource Control (RRC) Searchspace IE, only one CORESET is configured for a single LBT subband, the monitoring subband IE providing an indication of which LBT subband the UE is to monitor using a bitmap in which each bit of the bitmap corresponds to a different LBT subband. 
     
     
         9 . The apparatus of  claim 7 , wherein the processing circuitry is further configured encode, for transmission to the UE, a monitoring subband information element (IE) in a Radio Resource Control (RRC) Searchspace IE, only one CORESET of six physical resource blocks (PRBs) is configured for a single LBT subband, the monitoring subband IE providing an indication of which LBT subband the UE is to monitor using a bitmap in which each bit of the bitmap corresponds to a different set of six PRBs and a starting point of the CORESET to be monitored. 
     
     
         10 . The apparatus of  claim 7 , wherein the processing circuitry is further configured encode, for transmission to the UE, a monitoring subband information element (IE) in a Radio Resource Control (RRC) Searchspace IE, only one CORESET of six physical resource blocks (PRBs) is configured for a single LBT subband, the monitoring subband IE providing an indication of which LBT subband the UE is to monitor using a bitmap in which each bit of the bitmap corresponds to a different monitoring location offset with respect to a particular CORESET. 
     
     
         11 . The apparatus of  claim 2 , wherein the processing circuitry is further configured to:
 determine a channel occupancy time (COT) for transmission of the GC-PDCCH and PDSCH;   configure multiple monitoring opportunities during the COT, the monitoring opportunities for transmission of the GC-PDCCH;   determine whether transmission of the GC-PDCCH is able to be performed in an initial monitoring opportunity of the monitoring opportunities; and   in response to a determination that transmission of the GC-PDCCH is unable to be performed in the initial monitoring opportunity, encode the GC-PDCCH in a next monitoring opportunity.   
     
     
         12 . The apparatus of  claim 1 , wherein the processing circuitry is further configured to:
 determine a channel occupancy time (COT) for transmission of the PDSCH;   encode, during an initial portion of the COT, the PDSCH on all LBT bandwidths of the BWP, puncturing symbols of one or more unavailable LBT bandwidths of the LBT bandwidths during the initial portion of the COT; and   rate match the PDSCH based on the at least one available LBT bandwidth and limit transmission of the PDSCH to the at least one available LBT bandwidth during a remaining portion of the COT after the initial portion of the COT.   
     
     
         13 . The apparatus of  claim 1 , wherein the processing circuitry is configured to encode, for transmission to the UE, downlink control information (DCI) format 2_0 of a group common physical downlink control channel (GC-PDCCH) on the at least one available LBT bandwidth, the DCI format 2_0 containing a bitmap in which each bit indicates whether the LBT procedure was successful for a corresponding LBT bandwidth of the BWP. 
     
     
         14 . The apparatus of  claim 13 , wherein the processing circuitry is configured to:
 determine that LBT outcomes for the LBT bandwidths are unavailable prior to transmission of the DCI; and   in response to a determination that the LBT outcomes are unavailable, provide a LBT outcome in the DCI selected from a set of LBT outcomes, the set of LBT outcomes including: all LBT bandwidths are available, all LBT bandwidths are unavailable, or use of a specific bit of the bitmap to indicate that the LBT outcomes are unavailable.   
     
     
         15 . The apparatus of  claim 1 , wherein the processing circuitry is further configured to:
 determine whether carrier aggregation on an unlicensed band and licensed band is available; and   in response to a determination that the carrier aggregation is available, encode the indication in a group common physical downlink control channel (GC-PDCCH) on the licensed band rather than the unlicensed band.   
     
     
         16 . A computer-readable storage medium that stores instructions for execution by one or more processors of a 5 th  generation NodeB (gNB), the instructions when executed configure the one or more processors to:
 determine, based on performance of a listen-before-talk (LBT) procedure, which one or more LBT bandwidths in a bandwidth part (BWP) are available in an unlicensed channel;   encode, for transmission to a user equipment (UE) on an available LBT bandwidth of the one or more LBT bandwidths that are available in the unlicensed channel, an indication of the one or more LBT bandwidths that are available in the unlicensed channel; and   encode, for transmission to the UE, a physical downlink shared channel (PDSCH) using at least one available LBT bandwidth of the one or more LBT bandwidths.   
     
     
         17 . The medium of  claim 16 , wherein the instructions when executed configure the one or more processors to encode, for transmission to the UE, the indication in downlink control information (DC) format 2_0 of a group common physical downlink control channel (GC-PDCCH) on the available LBT bandwidth. 
     
     
         18 . A computer-readable storage medium that stores instructions for execution by one or more processors of a user equipment (UE), the instructions when executed configure the one or more processors to:
 decode, from a 5 th  generation NodeB (gNB) on one of one or more listen-before-talk (LBT) bandwidths in a bandwidth part (BWP) on an unlicensed channel, an indication of one or more LBT bandwidths that are available for transmission of a physical downlink shared channel (PDSCH); and   decode, from the gNB, the PDSCH on at least one available LBT bandwidth of the one or more LBT bandwidths.   
     
     
         19 . The medium of  claim 18 , wherein the instructions when executed configure the one or more processors to decode, from the gNB, the indication in downlink control information (DCI) format 2_0 of a group common physical downlink control channel (GC-PDCCH) on the one of the one or more LBT bandwidths that are available in the unlicensed channel. 
     
     
         20 . The medium of  claim 18 , wherein the instructions when executed configure the one or more processors to
 during an initial portion of a channel occupancy time (COT) obtained by the gNB, one of:
 attempt to receive the PDSCH on all of the LBT bandwidths; 
 use blind detection of demodulation reference signals (DMRS) to detect the at least one available LBT bandwidth, or 
 decode a group common physical downlink control channel (GC-PDCCH) containing the indication and decode the PDSCH on punctured symbols of one or more unavailable LBT bandwidths of the LBT bandwidths indicated by the indication; and 
   during a remaining portion of the COT after the initial portion of the COT, use rate matching to decode the PDSCH on only the at least one available LBT bandwidth indicated by the indication.