Supplementary uplink in wireless systems
Supplementary uplink (SUL) may be used in wireless systems. Cell suitability criteria may be provided for cells configured with SUL. A Wireless Transmit/Receive Unit (WTRU) may receive paging with an indication of a carrier (e.g., SUL or regular uplink (RUL)) in which to initiate part or all of an initial access. A WTRU that may be performing response-driven paging may provide (e.g. explicit) beam information for beamforming of a paging message on a non-beamformed SUL. A handover (HO) procedure (e.g., carrier selection, configuration handling, HO failure, etc.) may be provided for a WTRU with a configured SUL. A WTRU may request a change of a configured UL. A WTRU may (e.g., autonomously) perform a switch to a different (e.g., configured) uplink, for example, when one or more conditions may be met (e.g., conditional switch). Semi-persistent scheduling (SPS) resources/configuration may be relocated from a first UL to a second UL.
1. A wireless transmit/receive unit (WTRU) comprising:
a processor configured to:
receive a first handover (HO) command to HO to a first cell associated with a first supplementary uplink (SUL) carrier and a first regular uplink (RUL) carrier, wherein the first HO command comprises an explicit indication of whether the first SUL carrier or the first RUL carrier to be used for random-access to complete the first HO;
perform HO to the first cell in accordance with the first HO command;
receive a second HO command to HO to a second cell associated with a second SUL carrier and a second RUL carrier;
select an UL carrier for the second HO command based on whether a downlink reference signal received power (DL-RSRP) is below a threshold, wherein, if the DL-RSRP is below the threshold, then the second SUL carrier is selected as the UL carrier for the second HO, and if the DL-RSRP carrier is equal to or above the threshold, then the second RUL carrier is selected as the UL carrier for the second HO; and
perform HO to the second cell in accordance with the second HO command.
2. The WTRU of claim 1 , wherein the first HO command is received via a dedicated RRC configuration.
3. The WTRU of claim 1 , wherein the threshold comprises an RSRP threshold that is specific to SUL carrier selection.
4. The WTRU of claim 1 , wherein the threshold applies to a plurality of bandwidth parts (BWPs) associated with the first cell.
5. The WTRU of claim 1 , wherein the processor is configured to receive the threshold when in an RRC_IDLE state when camped on the first cell.
6. The WTRU of claim 1 , wherein the first SUL carrier is in a frequency band that is lower than a frequency band of the first RUL carrier, and wherein the second SUL carrier is in a frequency band that is lower than a frequency band of the second RUL carrier.
7. A method performed by a wireless transmit/receive unit (WTRU), the method comprising:
receiving a first handover (HO) command;
determining that the first HO command comprises an explicit indication of one uplink (UL) carrier for HO;
selecting an UL carrier for the first HO command based on whether random-access channel (RACH) resources are provided for the first supplementary uplink (SUL) carrier or the first RUL carrier in the first HO command;
performing HO to the selected UL carrier indicated by the first HO command;
receiving a second HO command;
determining that the second HO command comprises a configuration for both a second SUL and a second RUL in the second HO command;
selecting an UL carrier for the second HO command based on whether a downlink reference signal received power (DL-RSRP) is below a threshold, wherein, if the DL-RSRP is below the threshold, then the second SUL carrier is selected as the UL carrier for the second HO, and if the DL-RSRP is equal to or above the threshold, then the second RUL carrier is selected as the UL carrier for the second HO; and
performing HO to the selected UL carrier indicated by the second HO command.
8. The method of claim 7 , wherein the first HO command is received via a dedicated RRC configuration.
9. The method of claim 7 , wherein the threshold comprises an RSRP threshold that is specific to SUL carrier selection.
10. The method of claim 7 , wherein the threshold applies to a plurality of bandwidth parts (BWPs) associated with the first cell.
11. The method of claim 7 , further comprising receiving the threshold when in an RRC_IDLE state when camped on the first cell.
12. The method of claim 7 , wherein the first SUL carrier is in a frequency band that is lower than a frequency band of the first RUL carrier, and wherein the second SUL carrier is in a frequency band that is lower than a frequency band of the second RUL carrier.