# US 12,225,409 B2 · Data transmission method and device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,225,409 B2 - Document ID: US12225409B2 - Status: Granted - Kind: B2 - Application number: 17/677,636 - Filed: 2022-02-22 - Published: 2022-06-02 - Granted: 2025-02-11 - Earliest claimed: 2019-08-22 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Bin Xu; Bingzhao Li; Lei Chen; Hong Wang - Web page: https://patentgrep.com/patent/US12225409B2 ## CPC - H04L 47/34: ensuring sequence integrity, e.g. using sequence numbers - H04L 12/1881: {with schedule organisation, e.g. priority, sequence management} - H04L 12/189: {in combination with wireless systems (selective distribution or broadcast in wireless communication networks H04W4/06)} - H04W 4/06: Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services - H04W 28/06: Optimizing {the usage of the radio link}, e.g. header compression, information sizing {, discarding information (system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract For data transmission when a communication manner between the network device and a plurality of terminal devices is switched from a unicast manner to a multicast manner, a data transmission method includes: A network device sends first indication information to a first terminal device, where the first indication information includes a first sequence number (SN), and the first indication information is used to indicate the first terminal device to receive a data packet in a multicast manner. The network device sends the data packet to the first terminal device and a second terminal device in the multicast manner based on the first SN. ## Claims ### Claim 1 A data transmission method, comprising: sending, by a network device, first indication information to a first terminal device, wherein the first indication information comprises a first sequence number (SN), wherein the first SN is determined based on a maximum sequence number SN2 of a data packet sent by the network device to a second terminal device in a unicast manner, and wherein the first indication information indicates that the first terminal device is to receive a data packet in a multicast manner; and sending, by the network device, the data packet to the first terminal device and the second terminal device in the multicast manner based on the first SN. ### Claim 2 (depends on 1) The method according to claim 1, wherein based on a maximum sequence number SN1 of a data packet sent by the network device to the first terminal device in a unicast manner being smaller than the maximum sequence number SN2 of the data packet sent by the network device to the second terminal device in the unicast manner, the method further comprises: sending, by the network device, a first data packet to the first terminal device in the unicast manner, wherein an SN of the first data packet comprises at least one SN between SN2 and SN1. ### Claim 3 (depends on 1) The method according to claim 1, wherein based on a maximum sequence number SN1 of a data packet sent by the network device to the first terminal device in a unicast manner being larger than the maximum sequence number SN2 of the data packet sent by the network device to the second terminal device in the unicast manner, the method further comprises: sending, by the network device, second indication information to the first terminal device, wherein the second indication information indicates an SN of a data packet on which the first terminal device is to skip performing duplicate detection, and wherein the SN of the data packet on which duplicate detection is to be skipped comprises at least one SN between SN1 and SN2. ### Claim 4 (depends on 1) The method according to claim 1, wherein the first indication information is carried in a control protocol data unit (PDU), a media access control control element, radio resource control signaling, or downlink control information. ### Claim 5 A data transmission method, comprising: receiving, by a first terminal device, first indication information from a network device, wherein the first indication information comprises a first sequence number (SN), wherein the first SN is determined based on a maximum sequence number SN2 of a data packet sent by the network device to a second terminal device in a unicast manner, and wherein the first indication information indicates that the first terminal device is to receive a data packet in a multicast manner; and receiving, by the first terminal device, the data packet from the network device in the multicast manner based on the first SN. ### Claim 6 (depends on 5) The method according to claim 5, wherein receiving the data packet from the network device in the multicast manner based on the first SN comprises: determining, by the first terminal device based on the first SN, an SN corresponding to a lower edge of a receive window in which the first terminal device is to receive the data packet in the multicast manner: or determining, by the first terminal device based on the first SN, an SN of an initial data packet to be received by the first terminal device in the multicast manner. ### Claim 7 (depends on 5) The method according to claim 5, wherein based on a maximum sequence number SN1 of a data packet sent by the network device to the first terminal device in a unicast manner being smaller than the maximum sequence number SN2 of the data packet sent by the network device to the second terminal device in the unicast manner, the method further comprises: receiving, by the first terminal device, a first data packet from the network device in the unicast manner, wherein an SN of the first data packet comprises at least one SN between SN2 and SN1. ### Claim 8 (depends on 5) The method according to claim 5, wherein based on a maximum sequence number SN1 of a data packet sent by the network device to the first terminal device in a unicast manner being larger than the maximum sequence number SN2 of the data packet sent by the network device to the second terminal device in the unicast manner, the method further comprises: receiving, by the first terminal device, second indication information from the network device, wherein the second indication information indicates an SN of a data packet on which the first terminal device is to skip performing duplicate detection, and wherein the SN of the data packet on which duplicate detection is to be skipped comprises at least one SN between SN1 and SN2. ### Claim 9 A communication apparatus, comprising: one or more processors; and a memory, wherein the memory stores processor-executable instructions: wherein the one or more processors are configured to execute the processor-executable instructions to facilitate the following being performed by the communication apparatus: sending first indication information to a first terminal device, wherein the first indication information comprises a first sequence number (SN), wherein the first SN is determined based on a maximum sequence number SN2 of a data packet sent by the communication apparatus to a second terminal device in a unicast manner, and wherein the first indication information indicates that the first terminal device is to receive a data packet in a multicast manner; and sending the data packet to the first terminal device and the second terminal device in the multicast manner based on the first SN. ### Claim 10 (depends on 9) The communication apparatus according to claim 9, wherein the one or more processors are further configured to execute the processor-executable instructions to facilitate the following being performed by the communication apparatus: based on a maximum sequence number SN1 of a data packet sent by the communication apparatus to the first terminal device in a unicast manner being smaller than the maximum sequence number SN2 of the data packet sent by the communication apparatus to the second terminal device in the unicast manner, sending a first data packet to the first terminal device in the unicast manner, wherein an SN of the first data packet comprises at least one SN between SN2 and SN1. ### Claim 11 (depends on 9) The communication apparatus according to claim 9, wherein the one or more processors are further configured to execute the processor-executable instructions to facilitate the following being performed by the communication apparatus: based on a maximum sequence number SN1 of a data packet sent by the communication apparatus to the first terminal device in a unicast manner being larger than the maximum sequence number SN2 of the data packet sent by the communication apparatus to the second terminal device in the unicast manner, sending second indication information to the first terminal device, wherein the second indication information indicates an SN of a data packet on which the first terminal device is to skip performing duplicate detection, and wherein the SN of the data packet on which duplicate detection is to be skipped comprises at least one SN between SN1 and SN2. ### Claim 12 (depends on 9) The communication apparatus according to claim 9, wherein the first indication information is carried in a control protocol data unit (PDU), a media access control control element, radio resource control signaling, or downlink control information. ### Claim 13 A communication apparatus, comprising: one or more processors; and a memory, wherein the memory stores processor-executable instructions: wherein the one or more processors are configured to execute the processor-executable instructions to facilitate the following being performed by the communication apparatus: receiving first indication information from a network device, wherein the first indication information comprises a first sequence number (SN), wherein the first SN is determined based on a maximum sequence number SN2 of a data packet sent by the network device to a second terminal device in a unicast manner, and wherein the first indication information indicates that the communication apparatus is to receive a data packet in a multicast manner; and receiving the data packet from the network device in the multicast manner based on the first SN. ### Claim 14 (depends on 13) The communication apparatus according to claim 13, wherein the one or more processors are further configured to execute the processor-executable instructions to facilitate the following being performed by the communication apparatus: determining, based on the first SN, an SN corresponding to a lower edge of a receive window in which the communication apparatus is to receive the data packet in the multicast manner: or determining, based on the first SN, an SN of an initial data packet to be received by the communication apparatus in the multicast manner. ### Claim 15 (depends on 13) The communication apparatus according to claim 13, wherein the one or more processors are further configured to execute the processor-executable instructions to facilitate the following being performed by the communication apparatus: based on a maximum sequence number SN1 of a data packet sent by the network device to the communication apparatus in a unicast manner being smaller than the maximum sequence number SN2 of the data packet sent by the network device to the second terminal device in the unicast manner, receiving a first data packet from the network device in the unicast manner, wherein an SN of the first data packet comprises at least one SN between SN2 and SN1. ### Claim 16 (depends on 13) The communication apparatus according to claim 13, wherein the one or more processors are further configured to execute the processor-executable instructions to facilitate the following being performed by the communication apparatus: based on a maximum sequence number SN1 of a data packet sent by the network device to the communication apparatus in a unicast manner being larger than the maximum sequence number SN2 of the data packet sent by the network device to the second terminal device in the unicast manner, receiving second indication information from the network device, wherein the second indication information indicates an SN of a data packet on which the communication apparatus is to skip performing duplicate detection, and wherein the SN of the data packet on which duplicate detection is to be skipped comprises at least one SN between SN1 and SN2.