Apparatuses, methods, and systems for increasing the transmission reliability for transmissions of a duplication bearer in a shared spectrum
Apparatuses, methods, and systems are disclosed for increasing the transmission reliability for transmissions of a duplication bearer in a shared or unlicensed spectrum. A UE apparatus for a mobile network (“NW”) includes a transceiver that initiates a listen before talk procedure (“LBT”) on shared spectrum, for transmission of a medium access control (“MAC”) protocol data unit (“PDU”) containing an original packet data convergence protocol (“PDCP”) PDU of a data radio bearer (“DRB”) configured for PDCP duplication, wherein PDCP duplication is deactivated for the DRB. The apparatus includes a processor that determines whether the LBT failed or succeeded and selectively enables PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.
1 . A User Equipment (“UE”) comprising:
a memory; and
a processor coupled to the memory, the processor configured to cause the UE to:
duplicate an original packet data convergence protocol (“PDCP”) protocol data unit (“PDU”) of a data radio bearer (“DRB”) configured for PDCP duplication, while PDCP duplication is deactivated for the DRB;
initiate a listen before talk procedure (“LBT”) on shared spectrum after duplicating the original PDCP PDU, wherein the LBT procedure is for transmission of a medium access control (“MAC”) PDU containing the original PDCP PDU;
determine whether the LBT failed or succeeded; and
activate PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.
2 . The UE of claim 1 , wherein prior to performing the LBT, the processor is configured to cause the UE to submit duplicate PDCP PDUs to one or more radio link control (“RLC”) entities associated with a PDCP entity of the data radio bearer and corresponding logical channels (“LCHs”) selected from a primary LCH and one or more secondary LCHs.
3 . The UE of claim 1 , wherein in response to receiving duplicate PDCP PDUs from a PDCP transmitting entity at one or more radio link control (“RLC”) entities, the processor is configured to cause the UE to pre-generate and store corresponding RLC PDUs at the one or more RLC entities pending a transmission of the duplicate PDCP PDUs.
4 . The UE of claim 3 , wherein the processor is configured to cause the UE to pre-generate the corresponding RLC PDUs without segmentation and each PDCP PDU is contained in one RLC PDU.
5 . The UE of claim 3 , wherein in response to receiving feedback from lower layers of the failure of the LBT for the transmission of the MAC PDU containing the original PDCP PDU carried on a primary logical channel (“LCH”), the processor is configured to cause the UE to retransmit the MAC PDU containing the original PDCP PDU on the primary LCH and transmit the pre-generated RLC PDUs stored at the RLC entities corresponding to one or more secondary LCHs.
6 . The UE of claim 5 , wherein in response to receiving an acknowledgement from the lower layers that a subsequent LBT succeeded for the transmission of a MAC PDU containing the original PDCP PDU corresponding to the primary LCH, the processor is configured to cause the UE to discard the pre-generated RLC PDUs stored at the RLC entities corresponding to the one or more secondary LCHs.
7 . The UE of claim 6 , wherein the processor is configured to cause the UE to reassign an RLC sequence number (“SN”) of subsequent RLC PDUs to avoid a SN gap being caused by discarding pending duplicate RLC PDUs that were not transmitted.
8 . The UE of claim 3 , wherein the processor is configured to cause the UE to submit the pre-generated RLC PDUs to a MAC layer and generate MAC PDUs containing the duplicated PDCP PDUs for transmission on one or more physical uplink shared channels (“PUSCHs”).
9 . The UE of claim 8 , wherein generated MAC PDUs are transmitted with a redundancy version that ensures that the transmissions are self-decodable.
10 . The UE of claim 1 , wherein prior to activating PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT, the processor is configured to cause the UE to receive configuration information comprising a priority threshold that indicates which of one or more predetermined duplication modes to use.
11 . The UE of claim 1 , wherein in response to receiving an acknowledgement of successful transmission and decoding of a respective MAC PDU containing the original PDCP PDU, the processor is configured to cause the UE to discard a copy of the MAC PDU pending in a hybrid automatic repeat request (“HARQ”) buffer for transmission.
12 . The UE of claim 11 , wherein the processor is configured to cause the UE to further discard one or more corresponding pending duplicate PDCP PDUs and one or more pending duplicate radio link control (“RLC”) PDUs in a hybrid automatic repeat request (“HARQ”) buffer for transmission based on HARQ feedback from a receiving entity.
13 . The UE of claim 12 , wherein the processor is configured to cause the UE to reassign an RLC sequence number (“SN”) of subsequent RLC PDUs to avoid a SN gap being caused by discarding the one or more pending duplicate RLC PDUs.
14 . The UE of claim 1 , wherein in response to determining that the transmission of the MAC PDU containing the original PDCP PDU was unsuccessful due to failure of the LBT, the processor is configured to cause the UE to:
adopt a lower channel access priority class value for subsequent retransmission attempts of one or more MAC PDUs carrying PDCP PDU duplicates; and/or
use a short LBT for subsequent retransmission attempts of one or more MAC PDUs carrying the PDCP PDU duplicates.
15 . A method performed by a user equipment (“UE”), the method comprising:
duplicating an original packet data convergence protocol (“PDCP”) protocol data unit (“PDU”) of a data radio bearer (“DRB”) configured for PDCP duplication, while PDCP duplication is deactivated for the DRB;
initiating a listen before talk procedure (“LBT”) on shared spectrum after duplicating the original PDCP PDU, wherein the LBT procedure is for a transmission of a medium access control (“MAC”) PDU containing the original PDCP PDU;
determining whether the LBT failed or succeeded; and
activating PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT.
16 . The method of claim 15 , wherein prior to performing the LBT, the method further comprises:
submitting duplicate PDCP PDUs to one or more radio link control (“RLC”) entities associated with a PDCP entity of the data radio bearer and corresponding logical channels (“LCHs”) selected from a primary LCH and one or more secondary LCHs.
17 . The method of claim 15 , wherein in response to receiving duplicate PDCP PDUs from a PDCP transmitting entity at one or more radio link control (“RLC”) entities, the method further comprises pre-generating and storing corresponding RLC PDUs at the one or more RLC entities pending a transmission of the duplicate PDCP PDUs.
18 . The method of claim 15 , wherein prior to activating PDCP duplication for the DRB in response to determining that the PDCP PDU was not transmitted due to failure of the LBT, the method further comprises receiving configuration information comprising a priority threshold that indicates which of one or more predetermined duplication modes to use.
19 . The method of claim 15 , wherein in response to receiving an acknowledgement of successful transmission and decoding of a respective MAC PDU containing the original PDCP PDU, the method further comprises discarding a copy of the MAC PDU pending in a hybrid automatic repeat request (“HARQ”) buffer for transmission.
20 . The method of claim 15 , wherein in response to determining that the transmission of the MAC PDU containing the original PDCP PDU was unsuccessful due to failure of the LBT, the method further comprises:
adopting a lower channel access priority class value for subsequent retransmission attempts of one or more MAC PDUs carrying PDCP PDU duplicates; and/or
using a short LBT for subsequent retransmission attempts of one or more MAC PDUs carrying the PDCP PDU duplicates.