IP Library › Granted Patent US 12676701
Granted Patent B2
US 12676701 · App. 18/006,557 · Granted Jul 7, 2026

MRB architecture with PDCP retransmission

Inventors: Prasad Reddy Kadiri (San Diego, CA); Ruiming Zheng (Beijing, CN); Alberto Rico Alvarino (San Diego, CA); Umesh Phuyal (San Diego, CA); Xipeng Zhu (San Diego, CA); Le Liu (San Jose, CA); Kazuki Takeda (Minato-ku, JP); Changlong Xu (Beijing, CN)
Assignee: QUALCOMM Incorporated
H04L1/1816H04W76/40
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Quick Facts
Patent No.
US 12676701
App. No.
18/006,557
Granted
Jul 7, 2026
Kind
B2
Abstract

Embodiments include systems and methods for supporting for supporting retransmission in a multicast session in a Fifth Generation (5G) New Radio (NR) (5G NR) radio access network (RAN). Various embodiments may provide an enhanced multicast radio bearer (MRB) architecture leveraging Packet Data Convergence Protocol (PDCP) status reporting by wireless devices to a base station of a 5G NR RAN. Various embodiments may support multiple Radio Link Control (RLC) entities, also referred to as RLC legs, in a multicast session. One or more multicast RLC legs may be used for multicast and/or unicast transmission to wireless devices and a unicast RLC leg may be used for unicast transmission to a specific wireless device. Various embodiments may enable PDCP level retransmission of PDCP protocol data units (PDUs).

Claims (85)

1 . A method for supporting retransmission in a multicast session, comprising:

receiving a Packet Data Convergence Protocol (PDCP) packet data unit (PDU) including a polling bit;

generating a PDCP status report indicating at least a first missing count (FMC) of a next not received PDCP PDU for the multicast session in response to receiving the PDCP PDU including the polling bit, wherein:

the PDCP PDU indicates that a PDCP status reporting condition for the multicast session has occurred, and

the polling bit being included based on at least one of a threshold associated with a number of PDCP PDUs sent or a threshold associated with a number of bytes of the PDCP PDUs sent;

sending the PDCP status report to a network entity, and

receiving a retransmitted PDCP PDU from the network entity via a unicast transport channel or a multicast transport channel, a unicast radio link control (RLC) entity associated with the unicast transport channel and a multicast RLC entity associated with the multicast transport channel, wherein the retransmitted PDCP PDU corresponds to the next not received PDCP PDU.

2 . The method of claim 1 , wherein:

the next not received PDCP PDU was scheduled to be received via the multicast transport channel; and

the retransmitted PDCP PDU is received via the multicast transport channel.

3 . The method of claim 1 , wherein:

the next not received PDCP PDU was scheduled to be received via the multicast transport channel; and

the retransmitted PDCP PDU is received via the unicast transport channel.

4 . The method of claim 1 , further comprising:

activating the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session.

5 . The method of claim 4 , further comprising:

receiving, from the network entity, an indication to deactivate the unicast RLC entity or to deactivate the multicast RLC entity; and

maintaining the unicast RLC entity or the multicast RLC entity indicated for deactivation in a suspended state.

6 . The method of claim 4 , wherein;

the unicast RLC entity operates in an acknowledge mode (AM) or an unacknowledged mode (UM); and

the multicast RLC entity operates in an UM or a transparent mode (TM).

7 . The method of claim 1 , further comprising:

activating the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session, wherein the multicast RLC entity operates in an acknowledge mode (AM);

configuring the multicast RLC entity with a first logical channel identifier (LCID) for multicast reception and a second LCID for unicast reception; and

configuring the unicast RLC entity with a third LCID for unicast reception.

8 . The method of claim 7 , further comprising:

receiving packets for the multicast session from the network entity associated with the first LCID, wherein the packets are hybrid automatic repeat request (HARQ) encoded with the first LCID and a group-radio network temporary identifier (G-RNTI);

receiving packets for the multicast session from the network entity associated with the second LCID, wherein the packets are HARQ encoded with the second LCID and a cell-radio network temporary identifier (C-RNTI); or

receiving packets for the multicast session from the network entity associated with the third LCID, wherein the packets are HARQ encoded with the third LCID and the C-RNTI.

9 . The method of claim 1 , further comprising:

activating the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session, wherein the multicast RLC entity operates in an unacknowledged mode (UM);

configuring the multicast RLC entity with a first logical channel identifier (LCID) for multicast reception; and

configuring the unicast RLC entity with a second LCID for unicast reception.

10 . The method of claim 9 , further comprising:

receiving packets for the multicast session from the network entity associated with the first LCID, wherein the packets are hybrid automatic repeat request (HARQ) encoded with the first LCID and a group-radio network temporary identifier (G-RNTI); or

receiving packets for the multicast session from the network entity associated with the second LCID, wherein the packets are HARQ encoded with the second LCID and a cell-radio network temporary identifier (C-RNTI).

11 . The method of claim 1 , further comprising:

activating the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session, wherein the multicast RLC entity operates in an acknowledge mode (AM) or an unacknowledged mode (UM) and the unicast RLC entity operations in an AM or a UM;

configuring the multicast RLC entity with a first logical channel identifier (LCID) for multicast reception; and

configuring the unicast RLC entity with a second LCID for unicast reception.

12 . The method of claim 11 , further comprising one of:

receiving packets for the multicast session from the network entity associated with the first LCID, wherein the packets are hybrid automatic repeat request (HARQ) encoded with the first LCID and a group-radio network temporary identifier (G-RNTI) or the packets are HARQ encoded with the first LCID and a cell-radio network temporary identifier (C-RNTI); or

receiving packets for the multicast session from the network entity associated with the second LCID, wherein the packets are HARQ encoded with the second LCID and the C-RNTI.

13 . A wireless device, comprising:

one or more processors and one or more memories coupled with the one or more processors, the one or more processors configured to cause the wireless device to:

receive a Packet Data Convergence Protocol (PDCP) packet data unit (PDU) including a polling bit;

generate a PDCP status report indicating at least a first missing count (FMC) of a next not received PDCP PDU for a multicast session in response to receiving the PDCP PDU including the polling bit, wherein:

the PDCP PDU indicates that a PDCP status reporting condition for the multicast session has occurred, and

the polling bit being included based on at least one of a threshold associated with a number of PDCP PDUs sent or a threshold associated with a number of bytes of the PDCP PDUs sent;

send the PDCP status report to a network entity, and

receive a retransmitted PDCP PDU from the network entity via a unicast transport channel or a multicast transport channel, a unicast radio link control (RLC) entity associated with the unicast transport channel and a multicast RLC entity associated with the multicast transport channel, wherein the retransmitted PDCP PDU corresponds to the next not received PDCP PDU.

14 . The wireless device of claim 13 , wherein:

the next not received PDCP PDU was scheduled to be received via the multicast transport channel; and

the retransmitted PDCP PDU is received via the multicast transport channel.

15 . The wireless device of claim 13 , wherein:

the next not received PDCP PDU was scheduled to be received via the multicast transport channel; and

the retransmitted PDCP PDU is received via the unicast transport channel.

16 . The wireless device of claim 13 , wherein the one or more processors are configured to cause the wireless device to:

activate the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session.

17 . The wireless device of claim 16 , wherein the one or more processors are configured to cause the wireless device to:

receive, from the network entity, an indication to deactivate the unicast RLC entity or to deactivate the multicast RLC entity; and

maintain the unicast RLC entity or the multicast RLC entity indicated for deactivation in a suspended state.

18 . The wireless device of claim 13 , wherein the one or more processors are configured to cause the wireless device to:

activate the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session, wherein the multicast RLC entity operates in an acknowledge mode (AM);

configure the multicast RLC entity with a first logical channel identifier (LCID) for multicast reception and a second LCID for unicast reception; and

configure the unicast RLC entity with a third LCID for unicast reception.

19 . The wireless device of claim 18 , wherein the one or more processors are configured to cause the wireless device to:

receive packets for the multicast session from the network entity associated with the first LCID, wherein the packets are hybrid automatic repeat request (HARQ) encoded with the first LCID and a group-radio network temporary identifier (G-RNTI);

receive packets for the multicast session from the network entity associated with the second LCID, wherein the packets are HARQ encoded with the second LCID and a cell-radio network temporary identifier (C-RNTI); or

receive packets for the multicast session from the network entity associated with the third LCID, wherein the packets are HARQ encoded with the third LCID and the C-RNTI.

20 . The wireless device of claim 13 , wherein the one or more processors are configured to cause the wireless device to:

activate the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session, wherein the multicast RLC entity operates in an unacknowledged mode (UM);

configure the multicast RLC entity with a first logical channel identifier (LCID) for multicast reception; and

configure the unicast RLC entity with a second LCID for unicast reception.

21 . The wireless device of claim 13 , wherein the one or more processors are configured to cause the wireless device to:

activate the unicast RLC entity associated with the unicast transport channel for a multicast radio bearer (MRB) of the multicast session and the multicast RLC entity associated with the multicast transport channel for the MRB of the multicast session, wherein the multicast RLC entity operates in an acknowledge mode (AM) or an unacknowledged mode (UM) and the unicast RLC entity operations in an AM or a UM;

configure the multicast RLC entity with a first logical channel identifier (LCID) for multicast reception; and

configure the unicast RLC entity with a second LCID for unicast reception.

22 . One or more non-transitory processor-readable media having stored thereon processor-executable instructions that, when executed by one or more processors of a wireless device, cause the wireless device to perform operations comprising:

receiving a Packet Data Convergence Protocol (PDCP) packet data unit (PDU) including a polling bit;

generating a PDCP status report indicating at least a first missing count (FMC) of a next not received PDCP PDU for a multicast session in response to receiving the PDCP PDU including the polling bit, wherein:

the PDCP PDU indicates that a PDCP status reporting condition for the multicast session has occurred, and

the polling bit being included based on at least one of a threshold associated with a number of PDCP PDUs sent or a threshold associated with a number of bytes of the PDCP PDUs sent;

sending the PDCP status report to a network entity, and

receiving a retransmitted PDCP PDU from the network entity via a unicast transport channel or a multicast transport channel, a unicast radio link control (RLC) entity associated with the unicast transport channel and a multicast RLC entity associated with the multicast transport channel, wherein the retransmitted PDCP PDU corresponds to the next not received PDCP PDU.